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The term "diverse spectrum" in networking typically refers to the various frequency bands or ranges of the electromagnetic spectrum that are utilized for wireless communication.

In the context of networking, two broad categories often discussed are the spectrum below 1 GHz (sub-1 GHz) and the spectrum above 6 GHz (6+ GHz).

Each of these frequency ranges has its own characteristics, advantages, and challenges.

In networking, the choice of frequency band depends on the specific use case, deployment scenario, and trade-offs between coverage and data rate requirements.

Hybrid approaches that leverage both low and high-frequency bands are often employed to achieve a balance between coverage and capacity in modern wireless networks.

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Still in early stages of implementation

5G uses mmWaves, alongside other things like radio astronomy, telecommunications and radar guns.

5G Also uses UHF, which has a lower frequency and is used for things such as TV broadcasting, WIFI, Bluetooth etc.

The maximum channel bandwidth for 5G NR (Sub-6GHz) is 100MHz, while mmWave is a larger 400MHz. Compared to LTE, 5G NR is designed to have a higher bandwidth efficiency of up to 99%, versus up to 90% in LTE, where only 18 MHz in a 20 MHz channel was effectively used.

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MIMO stands for Multiple-input multiple-output. While it involves multiple technologies, MIMO can essentially be boiled down to this single principle: a wireless network that allows the transmitting and receiving of more than one data signal simultaneously over the same radio channel.

Standard MIMO networks tend to use two or four antennas. Massive MIMO, on the other hand, is a MIMO system with an especially high number of antennas.

The advantage of a MIMO network over a regular one is that it can multiply the capacity of a wireless connection without requiring more spectrum. Reports point to considerable capacity improvements, and could potentially yield as much as a 50-fold increase in future.

While standard MIMO principles are already in use across multiple Wi-Fi and 4G standards, Massive MIMO will really come into into its own as our 5G networks develop. Indeed, Massive MIMO will be a key enabler and foundational component of super-fast mmWave 5G, which is starting to rollout in certain countries.

Massive MIMO’s ability to serve multiple users - and multiple devices - simultaneously within a condensed area while maintaining fast data rates and consistent performance makes it the perfect technology to address the needs of the 5G era.

Vodafone became the first European mobile network to deploy Massive MIMO when it commenced upgrading a number of its UK sites in June 2017. The operator targeted UK hotspots where MIMO’s key attributes could be best exploited, such as cities and sports stadiums.

In October 2018, Vodafone launched the first full 5G UK trial in Salford. This was the first to carry full 5G over a commercial network, and it utilised Massive MIMO technology in conjunction with 3.4GHz spectrum to do so. It has since rolled these tests out to Birmingham, Bristol, Cardiff, Glasgow, Liverpool and London.

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OVERVIEW

Device-to-device (D2D) communication often refers to the technology that allows user equipment (UE) to communicate with each other with or without the involvement of network infrastructures such as an access point or base stations. D2D is promising as it is used to make ultra-low latency communication possible. But who is using D2D and what are the real applications behind such technologies? In this white paper, learn about D2D and how it enables fifth generation (5G) wireless network communication from short-range wireless to vehicle-to- vehicle.

What Is D2D?

D2D refers to the communication between devices, which can be cell phones or vehicles. This technique opens new device-centric communication that often requires no direct communication with the network infrastructure, hence is expected to solve part of the network capacity issue as 5G promises more devices to be connected in faster, more reliable networks.

D2D Applications

Dedicated short-range communications (DSRC) is often tied with 802.11p, which is the Wi-Fi standard specific to the automotive industry that leads the next generation of connected cars. Recently, Volkswagen announced that it will provide WLANp as standard equipment on all its cars in Europe starting in 2019 [1]. This announcement could create ripple effects in the industry to promote accident-free driving and, ultimately, autonomous driving.

However, the challenges with 802.11p is that it will only talk to cars that can transceive its protocol. Although the technology relays information such as the weather update at the end of a tunnel and other safety-related messages to promote safe driving, it doesn’t work with cars that don’t carry WLANp. To support complete autonomous driving, communications via cellular networks are essential. This new area is often referred to as C-V2X, where “X” is “everything,” such as another car (V2V), pedestrians (V2P), networks (V2N), and so on. In this white paper, C- V2X is mainly used to reference LTE-V2X.

A major benefit that C-V2X delivers is it uses the existing LTE network infrastructure, according to the initial V2V standard completion announcement by 3GPP [2]. It promotes high data rate, high coverage, lower latency with 5G, and so on. Because of such high promises, now virtually every automotive company is looking at C-V2X as the next “it” technology that will pave the path to complete autonomous driving.

In Figure 1, an LTE BS, eNodeB or eNB, communicates with two UE’s as you know it today with a cellphone tower communicating with cellphones. In a scenario where the downlink (DL) communication between eNB and UE #2 breaks, UE #1 relays information to UE #2 so that UE#2 continues to transceive information without losing any, as shown in Figure 2.

Another benefit in this scenario is that if UE #2 sits at the cell edge where it receives poor signals, UE #1 helps to provide better signals, which then extends the coverage of the cellular services.

A major challenge of C-V2X is that it has yet to be tested or validated, unlike 802.11p that was standardized over 10 years ago. Phase 2 of the C-V2X standardization is expected to be introduced in December 2018 and cover the following topics [3]:

Carrier aggregation (up to eight PC5 carriers)

64-QAM

Study the gain and feasibility of shortened TTI (<1ms)

Study the gain and feasibility of transmit diversity

Conclusion

Whether D2D communications are developed with or without the network infrastructure in mind, it allows more devices to be connected with boosted data rate and reduced latency. D2D may be one of the essential technologies to support 5G wireless network challenges in many industries. However, there are other steps that need to be taken until the arrival of true autonomous driving, which some say will not come for another five to 10 years.

Some of what the industry has done is truly impressive. Tesla, for example, has been releasing cars whose hardware is claimed to be capable of full self-driving [4]. It automatically searches for parking space and parks itself, all after the driver steps out of the car.

The cringe some parents feel when they send their 16-year-old to drive on the road for the first time may come to an end soon. However, as we move forward in finalizing the standards, more development and prototyping are needed, some of which are already in progress by the cellular community as well as the automotive industry.

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A Software Defined Network (SDN) is a networking approach where network control is decoupled from the physical hardware and handled by software. This separation allows for more centralized, flexible, and efficient management of network resources, enabling network administrators to programmatically configure, manage, optimize, and secure network traffic from a centralized control point, rather than through individual hardware devices.

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Millimeter wave spectrum is the band of spectrum between 30 GHz and 300 GHz.

Mmw is used in telecommunications, short-range radar and airport security scanners.

Mmw spectrum can be used for high-speed wireless communications such as 802.11ad

802.11ad operates at 60 GHz

Higher frequencies were not strong enough for outdoor broadband applications

Mmw has high propagation loss and susceptibility to blockage from buildings and absorption from rain drops.

Antennas for millimeter wave devices are smaller than for other frequencies, making them more suitable

for small internet of things (IoT) devices.

In telecommunications, it is used for high-bandwidth WLANs and short-range personal area networks.

Mmw high bandwidth capacity is great for short-distance wireless transmission of ultra-high definition video

Mmw high bandwidth capacity is great for communications from small, low-power IoT devices.

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Simultaneous Transmission and Reception: Full-duplex systems can send and receive data at the same time on the same frequency, which effectively doubles the capacity of a wireless channel.

Self-Interference Cancellation: A major challenge in full-duplex communication is self-interference, where the outgoing signal from a transmitter can interfere with its own receiver. Advanced techniques are used to cancel this interference, making full-duplex communication feasible.

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Cognitive radio (CR) is a form of wireless communication in which a transceiver can intelligently detect which communication channels are in use and which ones are not.

It also minimizes interference to other users. And, by avoiding occupied channels, it increases spectrum efficiency and improves the quality of service (QoS) for users.

The three key capabilities that differentiate cognitive radio from traditional radio are:

Cognition: CR understands its geographical and operational environment.

Reconfiguration: According to this cognitive knowledge, CR can decide to dynamically and autonomously adjust its parameters.

Learning: CR can also learn from the experience, and experiment with new configurations in new situations.

The two main types of CR are heterogeneous and spectrum-sharing.

In heterogeneous CR, operators run several radio access networks (RANs) using the same or different radio access technology (RAT) protocols. Heterogeneous cognitive radio uses a network-centric approach, and the frequency bands allocated to the various RANs are fixed.

In spectrum-sharing CR, several RANs share the same frequency band. They also coordinate with each other to use unoccupied sub-bands intelligently and optimally.

In both CR types, radio resources are optimized, and the QoS is much better than it would be with traditional radio.

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Full-duplex communication refers to a communication system in which data can be transmitted and received simultaneously. In the context of wireless communication, full-duplex communication allows devices to send and receive data at the same time, enabling two-way communication without the need for switching between sending and receiving modes.

In traditional half-duplex communication, devices take turns sending and receiving data. For example, in a walkie-talkie system, one person talks while the other listens, and they need to alternate between transmitting and receiving. Full-duplex communication eliminates this need for alternation, allowing both parties to communicate simultaneously.

There are several technologies and techniques used to achieve full-duplex wireless communication:

1. Frequency Division Duplex (FDD): In FDD, different frequency bands are allocated for the uplink (transmitting) and downlink (receiving) directions. This separation allows for simultaneous two-way communication.

2. Time Division Duplex (TDD): TDD allocates different time slots for transmitting and receiving on the same frequency. Devices switch between sending and receiving during these predefined time intervals.

3. Spatial Division Duplex (SDD): This approach involves the use of multiple antennas to separate the transmit and receive signals spatially. By employing advanced signal processing techniques, it's possible to enable simultaneous transmission and reception on the same frequency.

4. In-Band Full-Duplex (IBFD): IBFD technology allows devices to transmit and receive signals on the same frequency at the same time. It employs sophisticated cancellation techniques to mitigate interference between the transmitted and received signals.

Full-duplex communication is essential for various applications, such as telecommunication networks, wireless systems, and data communication protocols. Achieving full-duplex operation in wireless communication can be challenging due to issues like self-interference, where the transmitted signal interferes with the received signal. However, advancements in signal processing, antenna design, and cancellation techniques have made it increasingly feasible to implement full-duplex wireless communication in various scenarios.

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Mobile Network Operators are trying to densify their network to try and reach everyone with their service. Obvioustly it results in them having more customers. They can do this in 2 ways. Using macro cells and small cells. Macro cells reach to a longer distance but work on a lower frequency rate, while small cells cover a shorter distance, but can work on a higher frequency.

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Sub-GHz (<1GHz, usually 920MHz) is usually used for applications that don't have to transmit much data, such as weather balloons. As the frequency is lower, this results in more range (up to several kilometers), efficiency ("Some end nodes will last up to 10 years on a single coin-cell battery." What Is Sub-GHz Wireless Communication? (daviteq.com)) and reduced costs of implementation.

Higher spectrums (>6GHz) such as mmWave are much faster and have higher performance, but unlike sub-GHz, the range is lacking and is likely to have interference from external sources such as walls.