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Random-access memory (RAM) is a valuable resource in any software development environment, but it's even more valuable on a mobile operating system where physical memory is often constrained. Although both the Android Runtime (ART) and Dalvik virtual machine perform routine garbage collection, this does not mean you can ignore when and where your app allocates and releases memory. You still need to avoid introducing memory leaks, usually caused by holding onto object references in static member variables, and release any objects at the appropriate time as defined by lifecycle callbacks.

This page explains how you can proactively reduce memory usage within your app. For information about how the Android operating system manages memory, see the Overview of Android Memory Management.

Monitor available memory and memory usage

Before you can fix the memory usage problems in your app, you first need to find them. The Memory Profiler in Android Studio helps you find and diagnose memory issues in the following ways:

1. See how your app allocates memory over time. The Memory Profiler shows a realtime graph of how much memory your app is using, the number of allocated Java objects, and when garbage collection occurs.

2. Initiate garbage collection events and take a snapshot of the Java heap while your app runs.

3. Record your app's memory allocations and then inspect all allocated objects, view the stack trace for each allocation, and jump to the corresponding code in the Android Studio editor.

Release memory in response to events

As described in Overview of Android Memory Management, Android can reclaim memory from your app in several ways or kill your app entirely if necessary to free up memory for critical tasks. To further help balance the system memory and avoid the system's need to kill your app process, you can implement theComponentCallbacks2 interface in your classes. The providedonTrimMemory() callback method allows your app to listen for memory related events when your app is in either the foreground or the background, and then release objects in response to app lifecycle or system events that indicate the system needs to reclaim memory.

For example, you can implement the onTrimMemory() callback to respond to different memory-related events as shown here:

The onTrimMemory() callback was added in Android 4.0 (API level 14). For earlier versions, you can use theonLowMemory(), which is roughly equivalent to theTRIM_MEMORY_COMPLETE event.

Check how much memory you should use

To allow multiple running processes, Android sets a hard limit on the heap size alloted for each app. The exact heap size limit varies between devices based on how much RAM the device has available overall. If your app has reached the heap capacity and tries to allocate more memory, the system throws an OutOfMemoryError.

To avoid running out of memory, you can to query the system to determine how much heap space you have available on the current device. You can query the system for this figure by calling getMemoryInfo(). This returns anActivityManager.MemoryInfo object that provides information about the device's current memory status, including available memory, total memory, and the memory threshold-the memory level at which the system begins to kill processes. TheActivityManager.MemoryInfo object also exposes a simple boolean, that tells you whether the device is running low on memory.

The following code snippet shows an example of how you can use the getMemoryInfo() method in your application.

Use more memory-efficient code constructs

Some Android features, Java classes, and code constructs tend to use more memory than others. You can minimize how much memory your app uses by choosing more efficient alternatives in your code.

Use services sparingly

Leaving a service running when it's not needed is one of the worst memory-management mistakes an Android app can make. If your app needs a service to perform work in the background, do not keep it running unless it needs to run a job. Remember to stop your service when it has completed its task. Otherwise, you can inadvertently cause a memory leak.

When you start a service, the system prefers to always keep the process for that service running. This behavior makes services processes very expensive because the RAM used by a service remains unavailable to other processes. This reduces the number of cached processes that the system can keep in the LRU cache, making app switching less efficient. It can even lead to thrashing in the system when memory is tight and the system can't maintain enough processes to host all the services currently running.

You should generally avoid use of persistent services because of the on-going demands they place on available memory. Instead, we recommend that you use an alternative implementation such as JobScheduler. For more information about how to useJobScheduler to schedule background processes, see Background Optimizations.

If you must use a service, the best way to limit the lifespan of your service is to use an IntentService, which finishes itself as soon as it's done handling the intent that started it. For more information, read Running in a Background Service.

Use optimized data containers

Some of the classes provided by the programming language are not optimized for use on mobile devices. For example, the generic implementation can be quite memory inefficient because it needs a separate entry object for every mapping.

The Android framework includes several optimized data containers, including SparseArray, SparseBooleanArray, andLongSparseArray. For example, theSparseArray classes are more efficient because they avoid the system's need to autobox the key and sometimes value (which creates yet another object or two per entry).

If necessary, you can always switch to raw arrays for a really lean data structure.

Be careful with code abstractions

Developers often use abstractions simply as a good programming practice, because abstractions can improve code flexibility and maintenance. However, abstractions come at a significant cost: generally they require a fair amount more code that needs to be executed, requiring more time and more RAM for that code to be mapped into memory. So if your abstractions aren't supplying a significant benefit, you should avoid them.

Use lite protobufs for serialized data

Protocol buffers are a language-neutral, platform-neutral, extensible mechanism designed by Google for serializing structured data-similar to XML, but smaller, faster, and simpler. If you decide to use protobufs for your data, you should always use lite protobufs in your client-side code. Regular protobufs generate extremely verbose code, which can cause many kinds of problems in your app such as increased RAM use, significant APK size increase, and slower execution.

For more information, see the "Lite version" section in the protobuf readme.

Avoid memory churn

As mentioned previously, garbage collections events don't normally affect your app's performance. However, many garbage collection events that occur over a short period of time can quickly eat up your frame time. The more time that the system spends on garbage collection, the less time it has to do other stuff like rendering or streaming audio.

Often, memory churn can cause a large number of garbage collection events to occur. In practice, memory churn describes the number of allocated temporary objects that occur in a given amount of time.

For example, you might allocate multiple temporary objects within a for loop. Or you might create new or objects inside the function of a view. In both cases, the app creates a lot of objects quickly at high volume. These can quickly consume all the available memory in the young generation, forcing a garbage collection event to occur.

Of course, you need to find the places in your code where the memory churn is high before you can fix them. For that, you should use the Memory Profiler in Android Studio.

Once you identify the problem areas in your code, try to reduce the number of allocations within performance critical areas. Consider moving things out of inner loops or perhaps moving them into a Factory based allocation structure.

Remove memory-intensive resources and libraries

Some resources and libraries within your code can gobble up memory without you knowing it. Overall size of your APK, including third-party libraries or embedded resources, can affect how much memory your app consumes. You can improve your app's memory consumption by removing any redundant, unnecessary, or bloated components, resources, or libraries from your code.

Reduce overall APK size

You can significantly reduce your app's memory usage by reducing the overall size of your app. Bitmap size, resources, animation frames, and third-party libraries can all contribute to the size of your APK. Android Studio and the Android SDK provide multiple tools to help you reduce the size of your resources and external dependencies. These tools support modern code-shrinking methods, such as R8 compilation. (Android Studio 3.3 and lower use ProGuard instead of R8 compilation.)

For more information about how to reduce your overall APK size, see the guide on how to reduce your app size.

Use Dagger 2 for dependency injection

Dependency injection frameworks can simplify the code you write and provide an adaptive environment that's useful for testing and other configuration changes.

If you intend to use a dependency injection framework in your app, consider using Dagger 2. Dagger does not use reflection to scan your app's code. Dagger's static, compile-time implementation means that it can be used in Android apps without needless runtime cost or memory usage.

Other dependency injection frameworks that use reflection tend to initialize processes by scanning your code for annotations. This process can require significantly more CPU cycles and RAM, and can cause a noticeable lag when the app launches.

Be careful about using external libraries

External library code is often not written for mobile environments and can be inefficient when used for work on a mobile client. When you decide to use an external library, you may need to optimize that library for mobile devices. Plan for that work up-front and analyze the library in terms of code size and RAM footprint before deciding to use it at all.

Even some mobile-optimized libraries can cause problems due to differing implementations. For example, one library may use lite protobufs while another uses micro protobufs, resulting in two different protobuf implementations in your app. This can happen with different implementations of logging, analytics, image loading frameworks, caching, and many other things you don't expect.

Although ProGuard can help to remove APIs and resources with the right flags, it can't remove a library's large internal dependencies. The features that you want in these libraries may require lower-level dependencies. This becomes especially problematic when you use an subclass from a library (which will tend to have wide swaths of dependencies), when libraries use reflection (which is common and means you need to spend a lot of time manually tweaking ProGuard to get it to work), and so on.

Also avoid using a shared library for just one or two features out of dozens. You don't want to pull in a large amount of code and overhead that you don't even use. When you consider whether to use a library, look for an implementation that strongly matches what you need. Otherwise, you might decide to create your own implementation.

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Manage your app's memory | Android Developers

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Random-access memory (RAM) is a valuable resource in any software development environment, but it's even more valuable on a mobile operating system where physical memory is often constrained. Although both the Android Runtime (ART) and Dalvik virtual machine perform routine garbage collection, this does not mean you can ignore when and where your app allocates and releases memory.

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RFC 6665 - SIP-Specific Event Notification

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RFC 6665 SIP-Specific Event Notification July 2012 Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents ( http://trustee.ietf.org/license-info) in effect on the date of publication of this document.

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RFC 4327 - Link Management Protocol (LMP) Management Information Base (MIB)

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This protocol is used within the Generalized MPLS (GMPLS) protocol suite to manage TE links.

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1.1 - EVOLUTION OF COMMUNICATION - STONE AGE TO MODERN AGE

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No matter what industry you're in, your products and services are designed to provide solutions to the problems your customers face. So why is it that so many of these carefully designed solutions fail to resonate with the target audience?

The truth is, sometimes our expertise comes back to bite us. We're so busy playing doctor, confident in our ability to relieve perceived pain points, that we never bother to ask the patient where it actually hurts.

To provide true value to your customers, you have to start by asking the right questions. Here are some recommendations to help get more out of your conversations.

Don't Make Assumptions

Whether you realize it or not, your preconceived notions influence your interaction with clients. For example, if you come in thinking your client's primary pain is poor time management you may ask questions differently, inadvertently leading the conversation. As a result, you won't gather new information or insight into where your client could actually use your assistance.

Ask the Right Questions

Unfortunately, there's no magic set of questions designed to reveal pain points across all industries. The types of questions you ask will vary by business, target audience and individual. Every conversation is different.

What you can do, however, is get into the habit of asking focused, open-ended questions. These are not only perfect conversation starters, but they also allow for a more open and mutually beneficial discussion. Consider the differences in the following real estate examples:

Leading question: "Don't you just love the Victorian style?"

Open-ended question: "What do you think of the property?"

The first question not only limits the conversation to Victorian homes, but also exposes how you feel about them and how you expect the client to respond. If you really want to focus the discussion on Victorian style homes, try a more neutral question, like "How do you feel about Victorian homes?".

The second question shows no bias. It allows the client to comment on the property as a whole and pinpoint specific likes and dislikes. For example, the client may be thrilled with the curbside appeal but not so much with the limited closet space.

By leaving the question open-ended, you create an opportunity for learning. Clients are able to think and converse more freely, and they often learn as much from the discussion as you do, identifying pain points they didn't even realize existed. This helps create a sense of urgency and a willingness to accept your expert advice.

Actively Listen

In everyday conversation, it's not uncommon for friends to interrupt one another with random thoughts or related stories. It's how we make connections. But when you're trying to discover a customer's pain points, interrupting is counterproductive.

Instead, actively listen to what the client is telling you. Make your connection by asking insightful follow-up questions. The more you engage and show you care about the problem, the more your client will be willing to share - and the more you'll learn.

After peeling back the layers, you may discover that you have experience and insight that will prove valuable to the customer - information that you wouldn't have thought to share initially. You may find that the source of the client's pain is actually in perfect alignment with one of your product offerings.

Find the Common Thread

While certain problems will prove unique to specific clients, many will be more universal. As you identify these trends, you can adjust your marketing strategies and re-evaluate product offerings to address these common pain points and make customers happier across the board.

Try These Suggestions

Now let's look at a few general examples of open-ended questions you can tweak and use to discover pain points for any industry. We've also included a marketing-specific answer for each question to give you an idea of how one of these conversations might go.
1. "What is the biggest challenge you're currently facing?"
This is a conversation starter, a question that just scratches the surface of the pain as the client feels it. It's designed to get the client talking. You don't know exactly where the conversation will go, but you know you're going to learn something new.

Example answer: "We've recently discovered several online reviews badmouthing our company and we're not sure how to handle it."
2. "What happens if the pain is left unchecked?"
Once you've identified a pain point, it helps to know what kind of havoc it's wreaking on the customer. Is it costing them time and money on the job or just putting a damper on their online reputation?

This type of question helps you assess the risks of doing nothing against the benefits of making a change. It also gives insight into the client's motivations for wanting to make changes.

Example answer: "We get a lot of business through word-of-mouth online, and we don't want these reviews to cost us customers."
3. "What has prevented you from relieving the pain thus far?"
This question not only helps you identify the potential obstacles a client is facing, but also the past and present solutions they've used to address the problem. If they've tried other solutions, you have an opportunity to follow up and ask about those experiences, what went wrong and what the client would have changed. Knowing the history can help you pinpoint a better alternative.

Example answer: "Honestly, we don't know anything about online reviews, so we're stuck for now."
4. "What should putting a new system in place do to solve the problem?"
You may have the perfect solution to the client's problem, but if their expectations aren't realistic, they may never be happy with the results. This question is about gauging and setting expectations.

Example answer: "We're hoping you can show us how to monitor and respond to online conversations that concern our business, whether that means on social media or review sites like Yelp."
5. "We've found that X is a common source of pain for our customers. How do you feel about it?"
Some people have a problem identifying specific pain points, and they could use your guidance. This type of question helps by providing a frame of reference for the client. You're not trying to sell them anything or lead them to a specific topic. Instead, you're offering up a topic of conversation and allowing them to open up about their own specific problems in relation to a known pain point.

Example answer: "We're getting the hang of social media. Our content gets a response. It's just hard finding time for it each week."

Wrap-up

If you really want to make your customers happy, don't pitch solutions based on guesswork. Take the time to talk to prospects and clients, ask open-ended questions and actively listen to the responses. You'll learn more and your product will improve.

And don't forget to tweak your marketing strategy once those pain points have been revealed. If you need help, you know where to find us!

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Pain Point Discovery: It's All About Asking the Right Questions - OutboundEngine

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No matter what industry you're in, your products and services are designed to provide solutions to the problems your customers face. So why is it that so many of these carefully designed solutions fail to resonate with the target audience? The truth is, sometimes our expertise comes back to bite us.

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AUSTINBy the end of this year, some residents of Los Angeles, Sacramento and two other U.S. cities are expected to be surfing the internet and watching movies over Verizon's 5G wireless networks. Verizon wants to take on the cable companies by launching 5G-based home broadband service in markets that it doesn't already serve with its Fios fiber-to-the-home offering.

"We are taking these markets very seriously," said Neeraj Garg, director of digital transformation at Verizon. Garg discussed Verizon's 5G plans during a panel this week at the 5G North America trade show here. He said that at this point there are still a number of "unknown unknowns," meaning questions the company has yet to identify or answer. "We are in this market to learn," he said.

One of the things Verizon wants to learn is how much time and money will be spent installing the customer-premises equipment that consumers will use to access the company's new network. In Sacramento, the company will use Samsung's indoor 5G router, which the FCC certified earlier this month.

Derek Johnston, director of marketing at Samsung, said technicians should be able to install the routers with minimal training-specifically, he said that installers won't have to be RF technicians and will be able to learn what they need to know by watching a training video. Those technicians could be Verizon employees or third-party contractors.

Samsung's Johnston added that, down the road, consumers will be installing their own 5G CPEs. He said the CPEs will need to be located near windows.

Samsung has developed an indoor router and an outdoor router for 5G. Johnston said the outdoor router is for customers who cannot get service using the indoor router. For example, someone living in an apartment might need to connect to an outdoor 5G router, he said.

Johnston said Samsung's 5G CPEs will eventually support Wi-Fi, but for now they use a cable to connect to the user's home Wi-Fi router. Users will continue to access the internet over Wi-Fi, but their Wi-Fi routers will connect to a 5G wireless network instead of a wired connection.

"People do not think of their home internet coming on wireless," said Verizon's Garg. "It's a mental shift. ... The biggest challenge is to change the customer perception."

"Our testing has proven this thing works but a lot of the challenge we face at this point is how do we build expectations?" said Garg's colleague Vipul Jha, a senior manager at Verizon. "The expectations from customers is a very tricky thing." Jha acknowledged that millennials are perhaps more comfortable getting broadband over wireless, but said a large portion of Verizon's existing customer base is older.

Jha said other issues Verizon is working through with its first 5G networks include working with cities to secure small cell sites, establishing line of sight connections to homes, and making sure that the entire home can be covered.

Verizon did not discuss pricing for its new 5G service during the panel. One of the panel members, James Childs of CBNL, predicted that 5G CPE price points will fall to $500 within a year. Of course, service providers will decide how much to charge consumers and may wrap the cost of the equipment into the monthly service fee.

Verizon is working with different equipment vendors in different markets. Samsung's Johnston said that in Los Angeles, Verizon will not use Samsung's customer-premises equipment or radio access equipment for its initial 5G fixed wireless service.

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Technicians may need to install Verizon's initial fixed 5G CPE

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AUSTINBy the end of this year, some residents of Los Angeles, Sacramento and two other U.S. cities are expected to be surfing the internet and watching movies over Verizon's 5G wireless networks. Verizon wants to take on the cable companies by launching 5G-based home broadband service in markets that it doesn't already serve with its Fios fiber-to-the-home offering.

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Aftershocks are a common feature of big earthquakes, but they usually occur relatively close to the tremor's epicenter.

For the first time, researchers have found evidence of earthquakes triggering seismic events on the other side of the globe, suggesting a ripple effect that could potentially be used to forecast catastrophes in the future.

Researchers at Oregon State University analysed nearly half a century of data on earthquakes and came to the startling conclusion that when big tremors strike, there's a good chance another quake will hit on the other side of the planet within the next few days.

"The test cases showed a clearly detectable increase over background rates," says agricultural scientist Robert O'Malley.

Most seismic events are caused by pieces of the crust grinding together as they're pushed and pulled by the gradual churn of the planet's molten guts.

Every now and then, when tension overcomes friction between those giant plates, there's a sudden release of energy that can often give rise to a cascade of smaller tremors along the boundary.

"Earthquakes are part of a cycle of tectonic stress buildup and release. As fault zones near the end of this seismic cycle, tipping points may be reached and triggering can occur," says O'Malley.

Those ripples of energy can give the surrounding surface a good shake, but there are also waves of pressure echoing down through the mantle. Not only have we long known about these, they're routinely used as giant sonar pings to study the planet's internal structure.

One particularly nasty quake that struck off the coast of the Indonesian island of Sumatra in 2004 made the entire globe ring like a bell, causing the whole crust to slowly jiggle up and down by as much as a centimeter (just under half an inch).

The planet-sized hum would have been too slow for people to feel, but it's not inconceivable that these reverberations just might have been big enough to tip distant pressure-points over the edge, setting off large earthquakes around the world.

Unfortunately, until now there's been no good evidence of a sizeable knock-on effect. Speculation is rife, but scientists have generally failed to see any confirming patterns.

Researchers in this new study wonder if they've been too constrained in their search.

This time they've widened the window of opportunity for distant powerful earthquakes over 5.0 on the Richter scale to strike to within three days of a major shake-up.

Even after excluding tremors that could be described as aftershocks, the team identified more earthquakes than would be expected within any given three-day period following seismic events that ring in over 6.0 on the scale.

The bigger the initial quake, the greater the chance of a follow-up. Interestingly, this jump is absent for the first 24 hours, which could help explain why other studies failed to identify a pattern.

What's more, most of these occurred within 30 degrees of the very opposite point on the other side of the globe.

The study made no attempt to shed light on possible explanations behind the increase in far distant earthquakes. For now, it's merely food for thought.

"The understanding of the mechanics of how one earthquake could initiate another while being widely separated in distance and time is still largely speculative," says O'Malley.

"But irrespective of the specific mechanics involved, evidence shows that triggering does take place, followed by a period of quiescence and recharge."

The findings contradict a 2011 study that looked at changes in earthquake frequency up to several months after large tremors.

The researchers suggest this new study may simply be more sensitive, though the contrast indicates there's plenty of research to be done before we can be confident there's a link.

Pinpointing exactly when and where catastrophic earthquakes will hit would have the potential to save a lot of lives, so any research that can help predict the likelihood of a tremor is bound to be useful.

This research was published in Nature Scientific Reports.

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Scientists Have Identified That Earthquakes Can Trigger Tremors a World Away

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Aftershocks are a common feature of big earthquakes, but they usually occur relatively close to the tremor's epicenter. For the first time, researchers have found evidence of earthquakes triggering seismic events on the other side of the globe, suggesting a ripple effect that could potentially be used to forecast catastrophes in the future.

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An everyday occurrence spotted when we turn on the tap to brush our teeth has baffled engineers for centuries -- why does the water splay when it hits the sink before it heads down the plughole?

Famous inventor and painter Leonardo da Vinci documented the phenomenon, now known as a hydraulic jump, back in the 1500s. Hydraulic jumps are harmless in our household sinks but they can cause violent waves, turbulence and whirlpools in deeper water.

Since the 1820s scientists have believed that hydraulic jumps occur partly as a result of the gravitational pull. But a paper published in the Journal of Fluid Mechanics has disproved this longstanding theory.

Rajesh Bhagat, a Chemical Engineering PhD student at St John's College, University of Cambridge, and first author of the paper, fired jets of water upwards and sideways onto flat surfaces, and witnessed exactly the same hydraulic jumps as those when the water flowed downwards.

But what was causing it? Bhagat suspected they could all affected by the same factors -- surface tension and viscosity.

By altering these attributes of the water he was able to accurately predict the size of the hydraulic jumps, regardless of which direction the water was moving -- debunking the 200-year-old gravitational theory as the cause of a kitchen sink type hydraulic jump. This kind of hydraulic jump is known as a circular hydraulic jump.

Professor Paul Linden, Director of Research at the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge and an author of the paper, described Bhagat's findings as 'ground breaking'.

He explained: "His experiments and theory show that the surface tension of the liquid is the key to the process and has this has never before been recognised even though the problem was discussed by da Vinci and many others since. This work represents a remarkable achievement in our understanding of the dynamics of thin layers of fluid."

Bhagat predicts that his findings could have wide reaching consequences for industries that have high levels of water consumption.

He said: "Knowing how to manipulate the boundary of a hydraulic jump is very important and now with this theory we can easily extend or reduce the boundary.

"Understanding this process has big implications and could reduce industrial water use dramatically. The new theory is already being used in practical work in the Chemical Engineering department. People can use this theory to find new ways to clean everything from cars to factory equipment."

Bhagat hopes his research will also be used to find new ways to help us use less water in the average household.

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nature of water; albert einstein; nuclear energy; chemistry; engineering; quantum physics; consumer electronics; inorganic chemistry

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Household phenomenon observed by Leonardo da Vinci finally explained

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An everyday occurrence spotted when we turn on the tap to brush our teeth has baffled engineers for centuries -- why does the water splay when it hits the sink before it heads down the plughole? Famous inventor and painter Leonardo da Vinci documented the phenomenon, now known as a hydraulic jump, back in the 1500s.

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Researchers have found a way to accelerate antimatter in a 1000x smaller space than current accelerators, boosting the science of exotic particles.

The new method could be used to probe more mysteries of physics, like the properties of the Higgs boson and the nature of dark matter and dark energy, and provide more sensitive testing of aircraft and computer chips.

The method has been modelled using the properties of existing lasers, with experiments planned soon. If proven, the technology could allow many more labs around the world to conduct antimatter acceleration experiments.

Particle accelerators in facilities such as the Large Hadron Collider (LHC) in CERN and the Linac Coherent Light Source (LCLS) at Stanford University in the United States, speed up elementary particles like protons and electrons.

These accelerated particles can be smashed together, as in the LHC, to produce particles that are more elementary, like the Higgs boson, which gives all other particles mass.

They can also be used to generate x-ray laser light, such as in the LCLS, which is used to image extremely fast and small process, like photosynthesis.

However, to get to these high speeds, the accelerators need to use equipment that is at least two kilometres long. Previously, researchers at Imperial College London had invented a system that could accelerate electrons using equipment only meters long.

Now a researcher at Imperial has invented a method of accelerating the antimatter version of electrons -- called positrons -- in a system that would be just centimetres long.

The accelerator would require a type of laser system that currently covers around 25 square metres, but that is already present in many physics labs. Dr Aakash Sahai, from the Department of Physics at Imperial reported his method today in the Physical Review Journal for Accelerators and Beams.

He said: "With this new accelerator method, we could drastically reduce the size and the cost of antimatter acceleration. What is now only possible by using large physics facilities at tens of million-dollar costs could soon be possible in ordinary physics labs."

"The technologies used in facilities like the Large Hadron Collider or the Linac Coherent Light Source have not undergone significant advances since their invention in the 1950s. They are expensive to run, and it may be that we will soon have all we can get out of them.

"A new generation of compact, energetic and cheap accelerators of elusive particles would allow us to probe new physics -- and allow many more labs worldwide to join the effort."

While the method is currently undergoing experimental validation, Dr Sahai is confident it will be possible to produce a working prototype within a couple of years, based on the Department's previous experience creating electron beams using a similar method.

The method uses lasers and plasma -- a gas of charged particles -- to produce, concentrate positrons and accelerate them to create a beam. This centimetre-scale accelerator could use existing lasers to accelerate positron beams with tens of millions of particles to the same energy as reached over two kilometres at the Stanford accelerator.

Colliding electron and positron beams could have implications in fundamental physics. For example, they could create a higher rate of Higgs bosons than the LHC can, allowing physicists to better study its properties. They could also be used to look for new particles thought to exist in a theory called 'supersymmetry', which would fill in some gaps in the Standard Model of particle physics.

The positron beams would also have practical applications. Currently, when checking for faults and fracture risks in materials such as aircraft bodies, engine blades and computer chips, x-rays or electron beams are used. Positrons interact in a different way with these materials than x-rays and electrons, providing another dimension to the quality control process.

Dr Sahai added: "It is particularly gratifying to do this work at Imperial, where our lab's namesake -- Professor Patrick Blackett -- won a Nobel Prize for his invention of methods to track exotic particles like antimatter. Professor Abdus Salam, another Imperial academic, also won a Nobel Prize for the validation of his theory of weak force made possible only using a pre-LHC positron-electron collider machine at CERN. It's wonderful to attempt to carry on this legacy."

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quantum physics; physics; optics; materials science; spintronics; inorganic chemistry; civil engineering; nuclear energy

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Mini antimatter accelerator could rival the likes of the Large Hadron Collider

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Researchers have found a way to accelerate antimatter in a 1000x smaller space than current accelerators, boosting the science of exotic particles. The new method could be used to probe more mysteries of physics, like the properties of the Higgs boson and the nature of dark matter and dark energy, and provide more sensitive testing of aircraft and computer chips.

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A new way of arranging advanced computer components called memristors on a chip could enable them to be used for general computing, which could cut energy consumption by a factor of 100.

This would improve performance in low power environments such as smartphones or make for more efficient supercomputers, says a University of Michigan researcher.

"Historically, the semiconductor industry has improved performance by making devices faster. But although the processors and memories are very fast, they can't be efficient because they have to wait for data to come in and out," said Wei Lu, U-M professor of electrical and computer engineering and co-founder of memristor startup Crossbar Inc.

Memristors might be the answer. Named as a portmanteau of memory and resistor, they can be programmed to have different resistance states -- meaning they store information as resistance levels. These circuit elements enable memory and processing in the same device, cutting out the data transfer bottleneck experienced by conventional computers in which the memory is separate from the processor.

However, unlike ordinary bits, which are 1 or 0, memristors can have resistances that are on a continuum. Some applications, such as computing that mimics the brain (neuromorphic), take advantage of the analog nature of memristors. But for ordinary computing, trying to differentiate among small variations in the current passing through a memristor device is not precise enough for numerical calculations.

Lu and his colleagues got around this problem by digitizing the current outputs -- defining current ranges as specific bit values (i.e., 0 or 1). The team was also able to map large mathematical problems into smaller blocks within the array, improving the efficiency and flexibility of the system.

Computers with these new blocks, which the researchers call "memory-processing units," could be particularly useful for implementing machine learning and artificial intelligence algorithms. They are also well suited to tasks that are based on matrix operations, such as simulations used for weather prediction. The simplest mathematical matrices, akin to tables with rows and columns of numbers, can map directly onto the grid of memristors.

Once the memristors are set to represent the numbers, operations that multiply and sum the rows and columns can be taken care of simultaneously, with a set of voltage pulses along the rows. The current measured at the end of each column contains the answers. A typical processor, in contrast, would have to read the value from each cell of the matrix, perform multiplication, and then sum up each column in series.

"We get the multiplication and addition in one step. It's taken care of through physical laws. We don't need to manually multiply and sum in a processor," Lu said.

His team chose to solve partial differential equations as a test for a 32x32 memristor array -- which Lu imagines as just one block of a future system. These equations, including those behind weather forecasting, underpin many problems science and engineering but are very challenging to solve. The difficulty comes from the complicated forms and multiple variables needed to model physical phenomena.

When solving partial differential equations exactly is impossible, solving them approximately can require supercomputers. These problems often involve very large matrices of data, so the memory-processor communication bottleneck is neatly solved with a memristor array. The equations Lu's team used in their demonstration simulated a plasma reactor, such as those used for integrated circuit fabrication.

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energy technology; technology; physics; electronics; computers and internet; computer science; information technology; distributed computing

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Memory-processing unit could bring memristors to the masses

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A new way of arranging advanced computer components called memristors on a chip could enable them to be used for general computing, which could cut energy consumption by a factor of 100. This would improve performance in low power environments such as smartphones or make for more efficient supercomputers, says a University of Michigan researcher.

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Replacing traditional computer chip components with light-based counterparts will eventually make electronic devices faster due to the wide bandwidth of light.

A new protective metamaterial "cladding" prevents light from leaking out of the very curvy pathways it would travel in a computer chip.

Because processing information with light can be more efficient than with electrons used in current devices, there is good reason to confine light onto a chip. But light and the bits of information it carries tend to leak and scatter out of the tiny components that must fit on a chip.

A Purdue University-led effort has built a novel cladding along the highways for light travel, called waveguides, to prevent information leaks -- particularly around sharp bends where light bounces off track and scatters. Information then gets lost or jumbled rather than communicated throughout a device. Preventing this could facilitate the integration of photonic with electric circuitry, increasing communication speed and reducing power consumption.

"We want the bits of information that we are sending in the waveguide to travel along tight bends and simultaneously not be lost as heat. This is a challenge," said Zubin Jacob, Purdue assistant professor of electrical and computer engineering.

What makes the waveguide cladding so unique is anisotropy, meaning that the cladding design enables light to travel at different velocities in different directions. By controlling the anisotropy of the cladding, the researchers prevented light from leaking off track into other waveguides where "crosstalk," or mixing, of information would occur. Instead, bits of information carried by light bounce off by "total internal reflection" and stay strongly confined within a waveguide.

"The waveguide we made is an extreme skin-depth structure, which means that any leakage that does happen will be really small," said Saman Jahani, Purdue graduate research assistant in electrical and computer engineering. "This approach can pave the way for dense photonic integration on a computer chip without worrying about light leakage."

Journal Reference:

Saman Jahani, Sangsik Kim, Jonathan Atkinson, Justin C. Wirth, Farid Kalhor, Abdullah Al Noman, Ward D. Newman, Prashant Shekhar, Kyunghun Han, Vien Van, Raymond G. DeCorby, Lukas Chrostowski, Minghao Qi, Zubin Jacob. Controlling evanescent waves using silicon photonic all-dielectric metamaterials for dense integration. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-04276-8

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optics; technology; microarrays; energy technology; information technology; computer science; hacking; computers and internet

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Trapping light that doesn't bounce off track for faster electronics

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Replacing traditional computer chip components with light-based counterparts will eventually make electronic devices faster due to the wide bandwidth of light. A new protective metamaterial "cladding" prevents light from leaking out of the very curvy pathways it would travel in a computer chip.

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Spectral images, which contain more color information than is obtainable with a typical camera, reveal characteristics of tissue and other biological samples that can't be seen by the naked eye. A new smartphone-compatible device that is held like a pencil could make it practical to acquire spectral images of everyday objects and may eventually be used for point-of-care medical diagnosis in remote locations.

Potential applications of the new device include detecting oxygen saturation in a person's blood, determining the freshness of meat in the grocery store and identifying fruit that is the perfect ripeness. The spectrometer could also make it easier to acquire spectral data in the field for scientific studies.

In The Optical Society (OSA) journal Biomedical Optics Express, the researchers describe how to make the new pencil-like spectrometer and demonstrate its ability to acquire spectral images of bananas, pork and a person's hand. The new device can detect wavelengths from 400 to 676 nanometers at 186 spots simultaneously.

"The easiest way to use a spectrometer is to wave it over the part of the body or object being examined," said first author Fuhong Cai, Hainan University, China. "However, many home-made portable spectrometers use a smartphone camera to acquire data and a phone cradle that contains other necessary optics. The cradle can be hard to align correctly and makes it awkward to wave the smartphone over the body."

Rather than using a smartphone camera to acquire images, the new spectrometer uses a commercially available complementary metal-oxide-semiconductor (CMOS) camera that wirelessly transmits images to a smartphone. This approach allowed the researchers to assemble a cylindrical spectral imaging device weighing just 140 grams (about 5 ounces) that is about the length of smartphone and just over 3 centimeters in diameter.
Using off-the-shelf components
The new pencil-like spectrometer uses all commercially-available components that can be purchased for less than $300 (US). The light source is an array of white LEDs, which connects to an off-the-shelf optical lens tube with the CMOS detector and other optical components necessary for spectral imaging.

One can use the pencil-like spectrometer simply by moving it across the target area by hand. This manual push-broom scanning process builds up a series of spectral images that are sent to a smartphone or computer where software stitches the spectral images together into a 3D spectral image data cube.

The researchers tested the spectrometer by using it to detect banana ripeness and levels of myoglobin -- the iron-containing protein that gives meat its color -- in a piece of pork. They also used it to scan a person's hand, obtaining a 16-second video containing 200 spectral images. From the 3D spectral images, the researchers could distinguish five fingers and the palm and saw differences in hemoglobin distribution in various parts of the hand.

The researchers are also interested in using their compact imaging spectrometer for environmental monitoring. "We're developing distributed spectral cameras that could be used for a wide range of ocean surveys, such as detecting dissolved organic matter in water or pigments that indicate early signs of harmful algal blooms," said Cai. "Since the imaging spectrometer can connect to any type of camera, we are also examining the idea of attaching it to the camera of an autonomous vehicle to create a remote ocean sensing system."
Optimizing the system
Although using commercially-available components to make the prototype means that anyone can assemble the device, it also places some limits on resolution and sensitivity. For example, the prototype can only resolve wavelengths that differ by at least 17 nanometers.

"We expect significant spectral resolution improvements in the future by using an improved camera with a long focal length lens," said Dan Wang, Beijing University of Chemical Technology, China, a member of the research team. "These improvements would expand the applications for the device."

The researchers also plan to develop software to make the spectral imager even more useful. "We want to develop ways to use machine learning algorithms to analyze the massive amounts of data that could be collected with the portable spectra imager," said Sailing He, Zhejiang University, China, a member of the research team. "We also want to create software for smartphones that uses spectral imaging data to measure meat freshness, for example."

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medical imaging; medical devices; today's healthcare; medical technology; consumer electronics; telecommunications; photography; mobile computing; information technology

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Wireless handheld spectrometer transmits data to smartphone: Easy-to-use spectrometer costs less than $300, holds promise for remote medical diagnostics

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Spectral images, which contain more color information than is obtainable with a typical camera, reveal characteristics of tissue and other biological samples that can't be seen by the naked eye. A new smartphone-compatible device that is held like a pencil could make it practical to acquire spectral images of everyday objects and may eventually be used for point-of-care medical diagnosis in remote locations.

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Researchers in the Cockrell School of Engineering at The University of Texas at Austin have developed a centimeter-accurate GPS-based positioning system that could revolutionize geolocation on virtual reality headsets, cellphones and other technologies, making global positioning and orientation far more precise than what is currently available on a mobile device.

The researchers' new system could allow unmanned aerial vehicles to deliver packages to a specific spot on a consumer's back porch, enable collision avoidance technologies on cars and allow virtual reality (VR) headsets to be used outdoors. The researchers' new centimeter-accurate GPS coupled with a smartphone camera could be used to quickly build a globally referenced 3-D map of one's surroundings that would greatly expand the radius of a VR game. Currently, VR does not use GPS, which limits its use to indoors and usually a two- to three-foot radius.

"Imagine games where, rather than sit in front of a monitor and play, you are in your backyard actually running around with other players," said Todd Humphreys, assistant professor in the Department of Aerospace Engineering and Engineering Mechanics and lead researcher. "To be able to do this type of outdoor, multiplayer virtual reality game, you need highly accurate position and orientation that is tied to a global reference frame."

Humphreys and his team in the Radionavigation Lab have built a low-cost system that reduces location errors from the size of a large car to the size of a nickel -- a more than 100 times increase in accuracy. Humphreys collaborated with Professor Robert W. Heath from the Department of Electrical and Computer Engineering and graduate students on the new technology, which they describe in a recent issue of GPS World.

Centimeter-accurate positioning systems are already used in geology, surveying and mapping, but the survey-grade antennas these systems employ are too large and costly for use in mobile devices. The breakthrough by Humphreys and his team is a powerful and sensitive software-defined GPS receiver that can extract centimeter accuracies from the inexpensive antennas found in mobile devices -- such precise measurements were not previously possible. The researchers anticipate that their software's ability to leverage low-cost antennas will reduce the overall cost of centimeter accuracy, making it economically feasible for mobile devices.

Humphreys and his team have spent six years building a specialized receiver, called GRID, to extract so-called carrier phase measurements from low-cost antennas. GRID currently operates outside the phone, but it will eventually run on the phone's internal processor.

To further develop this technology, Humphreys and his students recently co-founded a startup, called Radiosense. Humphreys and his team are working with Samsung to develop a snap-on accessory that will tell smartphones, tablets and virtual reality headsets their precise position and orientation.

The researchers designed their system to deliver precise position and orientation information -- how one's head rotates or tilts -- to less than one degree of measurement accuracy. This level of accuracy could enhance VR environments that are based on real-world settings, as well as improve other applications, including visualization and 3-D mapping.

Additionally, the researchers believe their technology could make a significant difference in people's daily lives, including transportation, where centimeter-accurate GPS could lead to better vehicle-to-vehicle communication technology.

"If your car knows in real time the precise position and velocity of an approaching car that is blocked from view by other traffic, your car can plan ahead to avoid a collision," Humphreys said.

Further information: http://gpsworld.com/accuracy-in-the-palm-of-your-hand/

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technology; virtual environment; engineering; geography; earthquakes; natural disasters; virtual reality; mobile computing; video games

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New centimeter-accurate GPS system could transform virtual reality and mobile devices

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Scientists have built a low-cost centimeter-accurate GPS system that reduces location errors from the size of a large car to the size of a nickel -- a more than 100 times increase in accuracy. The breakthrough is a powerful and sensitive software-defined GPS receiver that can extract centimeter accuracies from the inexpensive antennas found in mobile devices.

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LTE Air Interface Webinar - AIRCOM International

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This second webinar discusses LTE Air Interface, the link between a mobile device and the network, and a fundamental driver of the quality of the network.

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5G (5th generation mobile networks or 5th generation wireless systems) denotes the next major phase of mobile telecommunications standards beyond the current 4G/IMT-Advanced standards. NGMN Alliance or Next Generation Mobile Networks Alliance define 5G network requirements as: Data rates of several tens of Mb/s should be supported for tens of thousands of users.

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Follow Eli on the Vlog Channel: https://www.youtube.com/user/EliComputerGuyLive Info Level: Beginner Presenter: Eli the Computer Guy Date Created: August 2, 2010 Length of Class: 54 Minutes Tracks Telephone Systems Prerequisites None Purpose of Class This class introduces students to the basic components of telephone systems. Topics Covered Public Switched Telephone Network Central Offices Trunk Lines PBX and Voicemail Systems PBX Stations Voicemail Subcribers Class Notes Introduction Telephone systems are not complicated if you understand how they work.

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The Telecom Shop - Business Telephone Systems including VoIP & Broadband

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What is VoIP? What is SIP? Are they different? How do they work? Does your Business need a VoIP Phone System? See more https://www.thetelecomshop.com/uk/hosted-pbx-voip-service

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NEW CONTENT ON: http://www.FailedNormal.com Info Level: Beginner Presenter: Eli the Computer Guy Date Created: August 8, 2010 Length of Class: 60 Minutes Tracks Telephone Systems Prerequisites Introduction to Telephone Systems Introduction to Convergence Purpose of Class This class discusses the basic components and requirements for a business or enterprise Voice Over IP telephone system.

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Introduces SIP - the Session Initiation Protocol. The first lesson from http://sipsense.com, the smarter way to learn SIP. Check out http://youtu.be/FBNB-EhfHPI for an overview.

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The Session Initiation Protocol ( SIP) is a communications protocol for signaling and controlling multimedia communication sessions in applications of Internet telephony for voice and video calls, in private IP telephone systems, as well as in instant messaging over Internet Protocol (IP) networks.

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pls do solve the paper and send me 1. Which is not part of a GSM RAN? A) RBS B) MSC C) BSC D) TRC 2. What are the frequencies bands available for GSM System?

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SIGTRAN is the name, derived from signaling transport, of the former Internet Engineering Task Force (IETF) working group that produced specifications for a family of protocols that provide reliable datagram service and user layer adaptations for Signaling System 7 (SS7) and ISDN communications protocols. The SIGTRAN protocols are an extension of the SS7 protocol family.

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The BER Tester generates/detects unframed, framed, and fractional data that are defined in Pseudo Random Bit Sequence (PRBS).

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What happens to the speed of sound when the temperature changes? 

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What happens to the speed of sound when the temperature changes? 

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Good things come in small packages. This is especially true in the world of portable wireless communications systems. Cell phones, wearables, and implantable electronics have shrunk over time, which has made them more useful in many cases. But a critical component of these devices -- the antenna -- hasn't followed suit. Researchers haven't been able to get them much smaller, until now.

In a paper published online Tuesday in Nature Communications, Nian Sun, professor of electrical and computer engineering at Northeastern, and his colleagues describe a new approach to designing antennas. The discovery enables researchers to construct antennas that are up to a thousand times smaller than currently available antennas, Sun said.

"A lot of people have tried hard to reduce the size of antennas. This has been an open challenge for the whole society," Sun said. "We looked into this problem and thought, 'why don't we use a new mechanism?'"

Traditional antennas are built to receive and transmit electromagnetic waves, which travel fast -- up to the speed of light. But electromagnetic waves have a relatively long wavelength. That means antennas must maintain a certain size in order to work efficiently with electromagnetic radiation.

Instead of designing antennas at the electromagnetic wave resonance -- so they receive and transmit electromagnetic waves -- researchers tailored the antennas to acoustic resonance. Acoustic resonance waves are roughly 10 thousand times -- smaller than electromagnetic waves. This translates to an antenna that's one or two orders of magnitude smaller than even the most compact antennas available today.

Since acoustic resonance and electromagnetic waves have the same frequency, the new antennas would still work for cell phones and other wireless communication devices. And they would provide the same instantaneous delivery of information. In fact, researchers found their antennas performed better than traditional kinds.

Tiny antennas have big implications, especially for Internet of Things devices, and in the biomedical field. For example, Sun said the technology could lead to better bioinjectible, bioimplantable, or even bioinjestible devices that monitor health.

One such application that neurosurgeons are interested in exploring is a device that could sense neuron behavior deep in the brain. But bringing this idea to life has stumped researchers, until now.

"Something that's millimeters or even micrometers in size would make biomedical implantation much easier to achieve, and the tissue damage would be much less," Sun said.

Journal Reference:

Tianxiang Nan, Hwaider Lin, Yuan Gao, Alexei Matyushov, Guoliang Yu, Huaihao Chen, Neville Sun, Shengjun Wei, Zhiguang Wang, Menghui Li, Xinjun Wang, Amine Belkessam, Rongdi Guo, Brian Chen, James Zhou, Zhenyun Qian, Yu Hui, Matteo Rinaldi, Michael E. McConney, Brandon M. Howe, Zhongqiang Hu, John G. Jones, Gail J. Brown, Nian Xiang Sun. Acoustically actuated ultra-compact NEMS magnetoelectric antennas. Nature Communications, 2017; 8 (1) DOI: 10.1038/s41467-017-00343-8

Cite This Page:

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technology; optics; medical technology; telecommunications; mobile computing; communications; internet; computer science

# data[].attributes.attachment_link.title
Designing effective antennas 1000 times smaller

# data[].attributes.attachment_link.description
Good things come in small packages. This is especially true in the world of portable wireless communications systems. Cell phones, wearables, and implantable electronics have shrunk over time, which has made them more useful in many cases. But a critical component of these devices -- the antenna -- hasn't followed suit.

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Most modern websites store data in databases, and since database queries are relatively slow, most sites also maintain so-called cache servers, which list the results of common queries for faster access. A data center for a major web service such as Google or Facebook might have as many as 1,000 servers dedicated just to caching.

Cache servers generally use random-access memory (RAM), which is fast but expensive and power-hungry. This week, at the International Conference on Very Large Databases, researchers from MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL) are presenting a new system for data center caching that instead uses flash memory, the kind of memory used in most smartphones.

Per gigabyte of memory, flash consumes about 5 percent as much energy as RAM and costs about one-tenth as much. It also has about 100 times the storage density, meaning that more data can be crammed into a smaller space. In addition to costing less and consuming less power, a flash caching system could dramatically reduce the number of cache servers required by a data center.

The drawback to flash is that it's much slower than RAM. "That's where the disbelief comes in," says Arvind, the Charles and Jennifer Johnson Professor in Computer Science Engineering and senior author on the conference paper. "People say, 'Really? You can do this with flash memory?' Access time in flash is 10,000 times longer than in DRAM [dynamic RAM]."

But slow as it is relative to DRAM, flash access is still much faster than human reactions to new sensory stimuli. Users won't notice the difference between a request that takes .0002 seconds to process -- a typical round-trip travel time over the internet -- and one that takes .0004 seconds because it involves a flash query.
Keeping pace
The more important concern is keeping up with the requests flooding the data center. The CSAIL researchers' system, dubbed BlueCache, does that by using the common computer science technique of "pipelining." Before a flash-based cache server returns the result of the first query to reach it, it can begin executing the next 10,000 queries. The first query might take 200 microseconds to process, but the responses to the succeeding ones will emerge at .02-microsecond intervals.

Even using pipelining, however, the CSAIL researchers had to deploy some clever engineering tricks to make flash caching competitive with DRAM caching. In tests, they compared BlueCache to what might be called the default implementation of a flash-based cache server, which is simply a data-center database server configured for caching. (Although slow compared to DRAM, flash is much faster than magnetic hard drives, which it has all but replaced in data centers.) BlueCache was 4.2 times as fast as the default implementation.

Joining Arvind on the paper are first author Shuotao Xu and his fellow MIT graduate student in electrical engineering and computer science Sang-Woo Jun; Ming Liu, who was an MIT graduate student when the work was done and is now at Microsoft Research; Sungjin Lee, an assistant professor of computer science and engineering at the Daegu Gyeongbuk Institute of Science and Technology in Korea, who worked on the project as a postdoc in Arvind's lab; and Jamey Hicks, a freelance software architect and MIT affiliate who runs the software consultancy Accelerated Tech.

The researchers' first trick is to add a little DRAM to every BlueCache flash cache -- a few megabytes per million megabytes of flash. The DRAM stores a table which pairs a database query with the flash-memory address of the corresponding query result. That doesn't make cache lookups any faster, but it makes the detection of cache misses -- the identification of data not yet imported into the cache -- much more efficient.

That little bit of DRAM doesn't compromise the system's energy savings. Indeed, because of all of its added efficiencies, BlueCache consumes only 4 percent as much power as the default implementation.
Engineered efficiencies
Ordinarily, a cache system has only three operations: reading a value from the cache, writing a new value to the cache, and deleting a value from the cache. Rather than rely on software to execute these operations, as the default implementation does, Xu developed a special-purpose hardware circuit for each of them, increasing speed and lowering power consumption.

Inside a BlueCache server, the flash memory is connected to the central processor by a wire known as a "bus," which, like any data connection, has a maximum capacity. BlueCache amasses enough queries to exhaust that capacity before sending them to memory, ensuring that the system is always using communication bandwidth as efficiently as possible.

With all these optimizations, BlueCache is able to perform write operations as efficiently as a DRAM-based system. Provided that each of the query results it's retrieving is at least eight kilobytes, it's as efficient at read operations, as well. (Because flash memory returns at least eight kilobytes of data for any request, it's efficiency falls off for really small query results.)

BlueCache, like most data-center caching systems, is a so-called key-value store, or KV store. In this case, the key is the database query and the value is the response.

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solar energy; telecommunications; energy technology; engineering; computers and internet; information technology; computer science; hacking

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Caching system could make data centers more energy efficient: Flash-memory system could reduce power consumption of data center 'caches' by 90 percent

# data[].attributes.attachment_link.description
Most modern websites store data in databases, and since database queries are relatively slow, most sites also maintain so-called cache servers, which list the results of common queries for faster access. A data center for a major web service such as Google or Facebook might have as many as 1,000 servers dedicated just to caching.

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In today's data networks, traffic analysis -- determining which links are getting congested and why -- is usually done by computers at the network's edge, which try to infer the state of the network from the times at which different data packets reach their destinations.

If the routers inside the network could instead report on their own circumstances, network analysis would be much more precise and efficient, enabling network operators to more rapidly address problems. To that end, router manufacturers have begun equipping their routers with counters that can report on the number of data packets a router has processed in a given time interval.

But raw number counts are only so useful, and giving routers a special-purpose monitoring circuit for every new measurement an operator might want to make isn't practical. The alternative is for routers to ship data packets to outside servers for more complex analysis, but that technique doesn't scale well. A data center with 100,000 servers, for instance, might need another 40,000 to 50,000 servers just to keep up with the flood of router data.

Researchers at MIT, Cisco Systems, and Barefoot Networks have come up with a new approach to network monitoring that provides great flexibility in data collection while keeping both the circuit complexity of the router and the number of external analytic servers low. They describe the work in a paper they're presenting this week at the annual conference of the Association for Computing Machinery's Special Interest Group on Data Communication.

Dubbed Marple, the system consists of a programming language that enables network operators to specify a wide range of network-monitoring tasks and a small set of simple circuit elements that can execute any task specified in the language. Simulations using actual data center traffic statistics suggest that, in the data center setting, Marple should require only one traffic analysis server for every 40 or 50 application servers.
Future-proofing
"There's this big movement toward making routers programmable and making the hardware itself programmable," says Mohammad Alizadeh, the TIBCO Career Development Assistant Professor of Electrical Engineering and Computer Science at MIT and a senior author on the paper. "So we were really motivated to think about what this would mean for network-performance monitoring and measurement. What would I want to be able to program into the router to make the task of the network operator easier?

"We realized that it's going to be very difficult to try to figure this out by picking out some measurement primitives or algorithms that we know of and saying, here's a module that will allow you to do this, here's a module that will allow you to do that. It would be difficult to get something that's future-proof and general using that approach."

Instead, Alizadeh and his collaborators co-designed the Marple language and the circuitry required to implement Marple queries, with one eye on the expressive flexibility of the language and another on the complexity of the circuits required to realize that flexibility. The team included first author Srinivas Narayana, a postdoc at MIT's Computer Science and Artificial Intelligence Laboratory; Anirudh Sivaraman, Vikram Nathan, and Prateesh Goyal, all MIT graduate students in electrical engineering and computer science; Venkat Arun, an undergraduate at the Indian Institute of Technology Guwahati who visited MIT for a summer; Vimalkumar Jeyakumar of Cisco Tetration Analytics; and Changhoon Kim of Barefoot Networks.

The idea behind Marple is to do as much analysis on the router itself as possible without causing network delays, and then to send the external server summary statistics rather than raw packet data, incurring huge savings in both bandwidth and processing time.

Marple is designed to individually monitor the transmissions of every computer sending data through a router, a number that can easily top 1 million. The problem is that a typical router has enough memory to store statistics on only 64,000 connections or so.
One-way cache
Marple solves this problem through a variation on the common computer science technique of caching, in which frequently used data is stored close to a processing unit for efficient access. Each router has a cache in which it maintains statistics on the data packets it's seen from some fixed number of senders -- say, 64,000. If its cache is full, and it receives a packet from yet another sender -- the 64,001st -- it simply kicks out the data associated with one of the previous 64,000 senders, shipping it off to a support server for storage. If it later receives another packet from the sender it booted, it starts a new cache entry for that sender.

This approach works only if newly booted data can be merged with the data already stored on the server. In the case of packet counting, this is simple enough. If the server records that a given router saw 1,000 packets from sender A, and if the router has seen another 100 packets from sender A since it last emptied A's cache, then at the next update the server simply adds the new 100 packets to the 1,000 it's already recorded.

But the merge process is not so straightforward if the statistic of interest is a weighted average of the number of packets processed per minute or the rate at which packets have been dropped by the network. The researchers' paper, however, includes a theoretical analysis showing that merging is always possible for statistics that are "linear in state."

"Linear" means that any update to the statistic involves multiplying its current value by one number and then adding another number to that product. The "in state" part means that the multiplier and the addend can be the results of mathematical operations performed on some number of previous packet measurements.

"We found that for operations where it wasn't immediately clear how they'd be written in this form, there was always a way to rewrite them into this form," Narayana says. "So it turns out to be a fairly useful class of operations, practically."

The new work was supported by the National Science Foundation, the U.S. Defense Advanced Projects Agency, and Cisco Systems.

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telecommunications; technology; consumer electronics; engineering; computers and internet; hacking; information technology; computer modeling

# data[].attributes.attachment_link.title
Monitoring network traffic more efficiently: Programming language plus simple circuit design could let routers report on their own operation

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In today's data networks, traffic analysis -- determining which links are getting congested and why -- is usually done by computers at the network's edge, which try to infer the state of the network from the times at which different data packets reach their destinations.

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Hybrid Circuits: Combing Analog and Digital

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Hybrid Circuits: Combing Analog and Digital

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New research from North Carolina State University has found that combining digital and analog components in nonlinear, chaos-based integrated circuits can improve their computational power by enabling processing of a larger number of inputs.

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from research organizations

New research from North Carolina State University has found that combining digital and analog components in nonlinear, chaos-based integrated circuits can improve their computational power by enabling processing of a larger number of inputs. This "best of both worlds" approach could lead to circuits that can perform more computations without increasing their physical size.

Computer scientists and designers are struggling to keep up with Moore's law, which states that the number of transistors on an integrated circuit will double every two years in order to meet processing demands. They are rapidly reaching the limits of physics in terms of transistor size -- it isn't possible to continue shrinking the transistors to fit more on a chip.

Chaos-based, nonlinear circuits have been proposed as a solution to the problem, as one circuit can perform multiple computations instead of the current "one circuit, one task" design. However, the number of inputs that can be processed in chaos-based computing is limited by ambient noise, which decreases accuracy. Ambient noise refers to random signal fluctuations that can be caused by temperature variations, voltage fluctuations or semiconductor defects.

"Noise has always been a big problem in almost all engineering applications including computing devices and communications," says Vivek Kohar, postdoctoral research scholar at NC State and lead author of a paper describing the work. "Our system is nonlinear and so noise can be even more problematic."

To address the problem, the researchers created a hybrid system which uses a digital block of AND gates and an analog nonlinear circuit to distribute the computation between the digital and analog circuits. The result is an exponential reduction in computational time, which means that the output can be measured while the noise-based deviations are still small. In short, the computations are performed so quickly that noise doesn't have time to affect their accuracy.

To further improve the accuracy, Kohar and his colleagues' proposed solution couples multiple systems. This coupling provides a safety net that reduces the effect of noise-based deviations at the final stage.

"Think about mountaineering," says Kohar. "The climbers can climb individually but if one slips then he/she may have a dangerous fall. So they use ropes to connect them with each other. If one slips, the others will prevent their fall. Our system is somewhat like this, where all the systems are connected with each other all the time.

"The systems are tuned in such a way that at the time of measurement, our system is at the maxima or minima -- the points where the effects of noise are low in general and much lower if the systems are coupled. Considering the mountaineering example again, this means that we take the averages of climbers when they are at resting locations like the peak or in a valley, where the distances between them are smallest."

Journal Reference:

Vivek Kohar, Behnam Kia, John F. Lindner, William L. Ditto. Implementing Boolean Functions in Hybrid Digital-Analog Systems. Physical Review Applied, 2017; 7 (4) DOI: 10.1103/PhysRevApplied.7.044006

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electronics; technology; telecommunications; spintronics; computers and internet; spintronics research; computer science; information technology

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Hybrid circuits can increase computational power of chaos-based systems

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from research organizations New research from North Carolina State University has found that combining digital and analog components in nonlinear, chaos-based integrated circuits can improve their computational power by enabling processing of a larger number of inputs. This "best of both worlds" approach could lead to circuits that can perform more computations without increasing their physical size.

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Adtran TA5000 GUI loading with local ethernet connection 

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Adtran TA5000 GUI loading with local ethernet connection 

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TA5000 GUI JOB AID - local ETHERNET conn

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"A Signal Transfer Point (STP) is a router that relays SS7 messages between signaling end-points (SEPs) and other signaling transfer points (STPs). Typical SEPs include service switching points(SSPs) and service control points (SCPs). The STP is connected to adjacent SEPs and STPs via signaling links. Based on the address fields of the SS7 messages, the STP routes the messages to the appropriate outgoing signaling link. Edge STPs can also route based upon message body content using deep packet inspection techniques, and can provide address translations and screen content to limit the transfer of messages with dubious content or sent from unreliable sources. To meet stringent reliability requirements, STPs are typically provisioned in mated pairs."

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A Signal Transfer Point (STP) is a router that relays SS7 messages between signaling end-points (SEPs) and other signaling transfer points (STPs). Typical SEPs include service switching points (SSPs) and service control points (SCPs). The STP is connected to adjacent SEPs and STPs via signaling links.

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What is an #HLR?

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What is Home Location Register (HLR)? - Definition from Techopedia

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Home Location Register HLR Definition - A home location register (HLR) is a database containing pertinent data regarding subscribers authorized to use a...

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Source: https://docstore.mik.ua/univercd/cc/td/doc/product/ong/15400/r34docs/tl1guide/odntlcmd.htm

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Release Notes for Cisco Voice Switch Service Module (VXSM) Release 5.0.02

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Release Notes for Cisco Voice Switch Service Module (VXSM) Release 5.0.02

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Lucent Gateway Platform TL1 Commands Reference Guide

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Lucent Gateway Platform TL1 Commands Reference Guide

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Part Number 255-400-002R5.1.0.1 Issue 41, June 30, 2005 Software Version 5.1.0.1

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255400002R5.1.0.1_V1_Lucent Gateway Platform Release 5.1.0.1 TL1 Commands Reference Guide

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A breakthrough sourcebook to the challenges and solutions for mobile database systems This text enables readers to effectively manage mobile database systems (MDS) and data dissemination via wireless channels. The author explores the mobile communication platform and analyzes its use in the development of a distributed database management system.

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Browse links to IEEE Societies, Technical Councils and Committees, Standards Association Working Groups, Regional and Student sites and SIGs.

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Posted by Telecom Gujarat Forum
NOKIA BSC COMMAND
This command use for Nokia BSC.
Nokia Command List

NOKIA COMMANDS:
Hot Keys:

Ctrl + B repeats last and previous commands on the MML
Ctrl + Y interrupts current command being typed or run

Alarm monitoring:
ZAHO; displays current active alarms in actual MSC and BSC only
ZEOL:#; displays active alarms on BCF (BCF = Site Manager or CF)
ZEEI:BCF=#; displays the operational state of the site
ZEOH:date,time:BCF=#; displays alarm history for site for the date and time listed
ZAHO:ET,#; displays current alarms for that ET (PCM)
ZAHP:ET,#; displays alarm history for that ET
ZEEL:BL; displays locked Sites, Sectors and TRXs on BSC

Investigating Clear Codes:
ZTUT:CLR; displays current clear codes on the MSC
ZTUL:CLR; displays latest history of clear codes

Canceling Bogus alarms on a Site: (Perform both commands)
ZEOR:#:alarm #; cancels alarm on site
ZEFR:#:OMU; resets the OMU (Operations and Maintenance Unit)

Canceling Bogus alarms on a BSC:
ZACC:####; cancels the alarm using the consecutive # in which it came in
ZACA:####; cancels the alarm using the alarm identifier #

Locking and unlocking a Site:
ZEFS:bcf #:L; locks entire Site without Forced Handover
ZEFS:bcf #:U; unlocks entire Site

Locking and unlocking Sectors:
ZEQS:BTS=#:L; locks entire sector down without Forced Handover
ZEQS:BTS=#:L:FHO,#; shuts down entire sector with Forced Handover
ZEQS:BTS=#:U; unlocks entire sector

Locking and unlocking TRXs:
ZERS:BTS=#,TRX=#:L; locks TRX down without Forced Handover
ZERS:BTS=#,TRX=#:L:FHO,#; shuts down TRX with Forced Handover
ZERS: BTS=#,TRX=#:U; unlocks TRX

Resetting the Site or OMU:
ZEFR:#:SITE; restarts SITE
ZEFR:#:OMU; restarts OMU

Bouncing Lap D’s on a Site:
ZDTI:::PCM=#; displays Lap D channels for entire site
ZDTC:lap d #:BL; blocks desired Lap D channel
ZDTC:lap d #:WO; places Lap D channel in working state

Error Checking on an ET (PCM):
ZYMO:ET,#; checks error counter for specific ET
ZYEU:ET,#:SLIDL=5; resets error counter for specific ET

Querying the # of calls on a site:
ZERO:BTS=#; displays all calls on desired sector
ZERO:BTS=#,TRX=#; displays all calls on desired TRX only

Sparing or Rolling a BCSU:
ZUSI:BCSU; displays what BCSU the SP was previously on
ZFWO:BCSU=0&&8; displays what BCSU the BL condition is on
ZUSC:BCSU,#:SP; spares the BCSU with the BL condition on it
Y for Yes executes the command

Statusing Timeslots:
ZEEL::BCF=#; Status the timeslots on a BCF

Status ET alarms on a BSC
ZAHP:ET,:::; Show all ET's that are in alarm

Taking an ET out of Seperated State
ZUSC:ET,#:SE; Will place the ET in a Separated - No Hardware state
(SE-NH)

Status session for User ID and commands:
ZIGO: Displays commands run for BSC on specific date and time.

Reloading software on a site:
ZEWV:BCF #:BU; Reloads the software on a BCF

Checking OMC alarms:
Open a terminal and telnet to the IP
Log in
Run the following command: df –k

Taking an ET out of BL state:
ZUSC:ET,#:
WORKING
BLOCKED
TEST
SEPERATED
SEPERATED-NO HARDWARE
Go back up the tree to get it back into Working

Rolling the BCCH on a Sector:
ZDTI:::PCM=#; Find out what TSL the radio is on that you want the BCCH on
ZDTC:lapd:BL; Block the TSL on the radio that the BCCH is going to
ZDTC:lapd:AL; Allow activation of the TSL that the BCCH is going to
ZDTC:lapd:WO; Brings TSL to a working state that the BCCH is going to
ZDTI:::PCM=#; Find out what TSL the radio that HAD the BCCH is on
ZDTC:lapd:AD; Deny Activation of the TSL that HAD the BCCH on it
ZDTC:lapd:BL; Block the TSL that the BCCH was on
ZDTC:lapd:WO; Brings the TSL to a working state

Clearing Circuit Releasing Failed in CAS alarms:

The alarm that you are talking about happens on MF circuits and is caused by the LEC not releasing or acknowledging us quick enough. Do to the latency, the Nokia locks out the trunk in question. When you see this alarm you should assume that it is 911 related and the issue needs to be corrected ASAP. The alarm field will be shown below.

SLMSC001 CASU-1 SWITCH 2005-11-27 00:07:37.44
*** ALARM CASU-1 1E001-00 SI9_SO
(9952) 2153 CIRCUIT RELEASING FAILED IN CAS
1081d 13d 29 0823 01 FF 01 02 01 01 10 00 00 00

If you look above I have highlighted in red the circuit that needs to be reset (1081-13). If you take the circuit to a NU state for about 30 seconds and then back to WO it should clear.

ZCEC:CRCT=1081-1:BA;
ZCEC:CRCT=1081-1:NU;
ZCEC:CRCT=1081-1:BA;
ZCEC:CRCT=1081-1:WO;

Also, you should get a Low Traffic Capacity alarm with supplementary information. I have the alarm listed below and the supplementary info is in red (02 0386). If you convert 386 from HEX to Decimal it comes out to 902. At that time you can do the command ZRCI:SEA=3:CGR=902:PRINT=5:; and look at the circuit group.

SLMSC001 CM-1 SWITCH 2005-11-29 08:07:22.06
CANCEL CM-1 1A003-03 KICKER
(0178) 2087 LOW TRAFFIC CAPACITY ON CIRCUIT GROUP
02 0386

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Ericsson worldwide

Our powerful and flexible Mobile Switching Center is the most efficient and reliable mobile switch on the market.

Product description

Mobile Switching Center (MSC) is the primary service-delivery node for GSM and WCDMA handling voice calls, SMS and services such as faxing.

The MSC sets up and releases the end-to-end connection, handles mobility and hand-over requirements during the call, and takes care of charging and real-time pre-paid account monitoring. It is well acknowledged for its high in-service performance and superb reliability under high traffic loads.

Evolve the network

MSC has a clear, smooth evolution path to mobile softswitch solution-based networks, allowing operators to reuse their investment while preparing for enhanced service capabilities.

Based on 3GPP standards and supported by the world's largest multivendor interoperability program, MSC can be smoothly integrated into mixed-vendor networks, to maintain the possibility of choosing vendors and technology in the future.

Generate revenue and save money

The MSC software can be easily customized giving you greater flexibility and the opportunity to clearly differentiate your service offering, while reducing time to market for new services.

The well-integrated hardware helps minimize equipment footprint and power consumption, which in turn reduces opex. Best-in-class total cost of ownership is further supported by smart operation and maintenance capabilities, and rationalization of hardware modules in standard magazines.

Press releases & publications

Training programs

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nortel pbx partner var rolm siemens telephone telephones voicemail cabling ascom telecorp meridian norstar bcm callpilot symposium voip ip telephony key systems phone phones digital data switch switches succession convergence gateway voice motorola canopy meridien polycom colaboration presence sip elite advantage dealer distributor bridgewave gigabit wireless lan wan trapeze wifi avaya office gold partner

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Nortel - DMS Mobile Switching Center (MSC)-Integrated Technology

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Integrated Technology is a converged solutions provider specializing in Nortel enterprise solutions and Motorola Canopy and Bridgewave Wireless solutions

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The latest trends in networking technology - Ericsson

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Immersive gaming, virtualization, connected stadiums: understanding what consumers want with the latest trends in networking technology let's you position your business to capture the full potential of future revenue opportunities.

# data[].attributes.body
An optical time-domain reflectometer (OTDR) is an optoelectronic instrument used to characterize an optical fiber. An OTDR is the optical equivalent of an electronic time domain reflectometer.

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Optical time-domain reflectometer - Wikipedia

# data[].attributes.attachment_link.description
An optical time-domain reflectometer ( OTDR) is an optoelectronic instrument used to characterize an optical fiber. An OTDR is the optical equivalent of an electronic time domain reflectometer. It injects a series of optical pulses into the fiber under test and extracts, from the same end of the fiber, light that is scattered ( Rayleigh backscatter) or reflected back from points along the fiber.

# data[].attributes.body
The T-carrier is a member of the series of carrier systems developed by AT&T Bell Laboratories for digital transmission of multiplexed telephone calls.

# data[].attributes.attachment_link.description
The T-carrier is a member of the series of carrier systems developed by AT&T Bell Laboratories for digital transmission of multiplexed telephone calls. The first version, the Transmission System 1 (T-1), was introduced in 1962 in the Bell System, and could transmit up to 24 telephone calls simultaneously over a single transmission line of copper wire.

# data[].attributes.body
The public switched telephone network (PSTN) is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telephony operators, providing infrastructure and services for public telecommunication.

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Public switched telephone network - Wikipedia

# data[].attributes.attachment_link.description
The public switched telephone network ( PSTN) is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telephony operators, providing infrastructure and services for public telecommunication. The PSTN consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all interconnected by switching centers, thus allowing most telephones to communicate with each other.

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Network switching subsystem (NSS) (or GSM core network) is the component of a GSM system that carries out call switching and mobility management functions for mobile phones roaming on the network of base stations.

# data[].attributes.attachment_link.description
Network switching subsystem ( NSS) (or GSM core network) is the component of a GSM system that carries out call switching and mobility management functions for mobile phones roaming on the network of base stations. It is owned and deployed by mobile phone operators and allows mobile devices to communicate with each other and telephones in the wider public switched telephone network (PSTN).

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Mobile Telephone Switching Office (MTSO / MSC)

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Mobile Telephone Switching Office (MTSO / MSC)

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Mobile Telephone Switching Office - Wikipedia

# data[].attributes.attachment_link.description
All cellular systems have at least one MTSO which will contain at least one MSC. The MSC is responsible for switching calls to mobile units as well as to the local telephone system, recording billing data and processing data from the cell site controllers.

# data[].attributes.attachment_link.description
Optical fiber connectors are used to join optical fibers where a connect/disconnect capability is required. Due to the polishing and tuning procedures that may be incorporated into optical connector manufacturing, connectors are generally assembled onto optical fiber in a supplier's manufacturing facility.

# data[].attributes.body
"Structured cabling is building or campus telecommunications cabling infrastructure that consists of a number of standardized smaller elements (hence structured) called subsystems."

# data[].attributes.attachment_link.description
Structured cabling design and installation is governed by a set of standards that specify wiring data centers, offices, and apartment buildings for data or voice communications using various kinds of cable, most commonly category 5e (CAT5e), category 6 (CAT6), and fiber optic cabling and modular connectors.

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"Beside mechanical destruction, another reason why one should avoid excessive bending of fiber-optic cables is to minimize microbending and macrobending losses. Microbending causes light attenuation induced by deformation of the fiber while macrobending causes the leakage of light through the fiber cladding and this is more likely to happen where the fiber is excessively bent."

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"A service control point (SCP) is a standard component of the Intelligent Network (IN) telephone system which is used to control the service. Standard SCPs in the telecom industry today are deployed using SS7, SIGTRAN or SIP technologies. The SCP queries the service data point (SDP) which holds the actual database and directory. SCP, using the database from the SDP, identifies the geographical number to which the call is to be routed. This is the same mechanism that is used to route 800 numbers."

# data[].attributes.attachment_link.description
A service control point (SCP) is a standard component of the Intelligent Network (IN) telephone system which is used to control the service. Standard SCPs in the telecom industry today are deployed using SS7, SIGTRAN or SIP technologies. The SCP queries the service data point (SDP) which holds the actual database and directory.