Question

Question 4 (total 20 marks)

Compare and discuss the diversity methods, the frequency bands and the modulation schemes used by different 5G standards.

Answer 1

Emerging Applications Changing Spectrum Use and Cellular Network Performance
Though earlier cellular wireless generations served applications other than mobile broadband, the bulk of 2G, 3G, and now 4G LTE cellular services are designed and dedicated to mobile broadband. The standards and technologies for previous cellular generations have predominantly supported mobile broadband cellular users in urban and suburban regions, with less of an emphasis in rural regions. The goal of 5G technologies, however, goes beyond merely serving mobile broadband, but offers key improvements that enable a much wider range of applications: enhanced mobile broadband (eMBB), ultra-reliable and low latency communications (URLLC), massive machine-type communications (MMC), and fixed wireless access (FWA).

Enhanced Mobile Broadband (eMBB)
Where 5G eMBB differs from 4G mobile broadband are 5G’s extreme data rates and ubiquitous urban coverage goals. With eMBB the IMT-2020 goals are to provide standard that facilitate peak download speeds to 20 Gbps, and reliable user data rates in urban environments of at least 100 Mbps with only 4 ms latency. Though current 4G mobile broadband speeds can reach peak speeds of hundreds of megabits per second, most urban users experience less than 10 Mbps speeds with latencies in the tens of milliseconds. Beyond rapid video downloads, 5G eMBB will enable use cases that open the door to augmented reality and virtual reality applications in real-time, throughout and urban environment.

This performance requires upgrades throughout the cellular networking stack, as well as technology enhancements for handsets. Much of the change in network architecture is currently happening, as major telecom companies are deploying more small cells to enable eMBB performance, where traditional homogeneous macro-cell architectures have proven incapable, especially in densely cluttered urban environments.

Ultra-reliable and Low Latency Communications (URLLC)
Though some areas experience cellular wireless performance that can be considered enterprise grade, most current cellular systems aren’t able to provide the reliability or latency requirements for critical applications, such as autonomous vehicles, mobile healthcare, factory automation, or emergency response. 5G URLLC aims to provide highly reliable, secure, and low latency communications that provide sub-1ms latency communications solid enough for use in applications that could mean life or death.

Enhancing cellular network reliability and reducing latency involves changes with how cellular handset, base station, and networking is done. These enhancements include new waveforms, lower latency hardware, and likely wireless networking approaches that enable frequency-agility, redundancy, and alternative network architecture types than a star network.

Massive Machine-type Communications (MMC)
Most cellular wireless users today are individuals using mobile handsets, but future cellular networks will likely be dominated by Internet of Things (IoT) devices intercommunicating, reporting sensor information, and acting on control data throughout modernized urban areas, factories, industrial installations, and transportation networks. Much, and maybe the majority, of future cellular communications will be between machines, which pose very different requirements than human users.

Dispersed IoT and machine devices are likely to require a very diverse range of communication requirements, making a single one-size-fits-all wireless communication protocol inviable. Hence, the new 5G standards are likely to include adaptable communication protocol methods, so that systems such as battery operated sensors with low-power and low-data rate requirements can use the same network technology as high-data rate and low-latency autonomous robots, for example. Previously cellular generations relied on using specific frequency bands for certain applications, which is less likely to be the solution for future cellular generations as spectrum congestion leads makes each frequency band more valuable.

Fixed Wireless Access (FWA)
Though sparsely used, 3G and 4G cellular networks have supported a range of pseudo-fixed wireless access systems, with hotspots and cellular modems. However, the enhanced data rate and low latency capability of 5G networks enables an attractive business use case of providing FWA to compete with other last-mile internet service. With greater bandwidth and advanced antenna technologies, many experts predict that 5G networks will be able to provide fiber-like performance and enable developed and developing markets with accessible internet and connectivity. Beyond massive multi-input multi-output (mMIMO) and beamforming capable antennas, FWA services also require bandwidth beyond what is available in the sub-6 GHz spectrum driving current cellular networkings. Large amounts of bandwidth, likely exceeding 1 GHz, will be necessary to provide fiber-like service. Hence, 5G cellular networks are including millimeter-wave frequency bands to enable new applications and dramatic increases in data rates compared to previously generations.

5G Frequencies Compared to 4G Frequencies
Early GSM cellular networks operated at 850 MHz and 1900 MHz. 2G and 3G networks change the modulation method but largely used the same portions of the spectrum with reorganized frequency bands. As 3G evolved, additional frequency bands were included as well as spectrum around 2100 MHz. 4G LTE technologies brought it additional spectrum and frequency bands, namely around 600 MHz, 700 MHz, 1.7/2.1 GHz, 2.3 GHz, and 2.5 GHz. All of the previous cellular network frequencies are based on licenses (Table 1).

The 5G frequency band plans are much more complex, as the frequency spectrum for sub-6 GHz 5G spans 450 MHz to 6 GHz, and millimeter-wave 5G frequencies span 24.250 GHz to 52.600 GHz, and also include unlicensed spectrum. Additionally, there may be 5G spectrum in the 5925 to 7150 MHz range and 64 GHz to 86 GHz range. Therefore, 5G will include all previous cellular spectrum and a large amount spectrum in the sub-6 GHz range, and beyond sub- 6 GHz is many times current cellular spectrum (Table 2 and Table 3). The initial 3GPP release of 5G New Radio Non-standalone (5G NR) standards included several sub-6 GHz frequency bands, designated FR1 (Table 2). The second 3GPP 5G release after IMT-2020 will include FR2 frequency bands in the millimeter-wave spectrum (Table 3).

As with previous cellular generations and 3GPP releases, various regions and countries will also likely adopt unique spectrum for 5G uses. The US FCC, for example, is considering opening 5.925 GHz to 6.425 GHz and 6.425 GHz to 7.125 GHz for unlicensed used and is consulting adding mobile broadband capability in the 3.7 GHz to 4.2 GHz spectrum. Currently, the FCC is actioning spectrum in the 27.5 GHz to 28.35 GHz, 24.25 GHz to 24.45 GHz, and 24.75 GHz 25.25 GHz, range for millimeter-wave 5G use. The FCC may also be considering opening 3.7 GHz to 4.2 GHz mid-band frequencies for 5G, and may also be considering opening 4.9 GHz public safety bands for 5G access. Moreover, the FCC may also make additional bands available for 5G in the 2.75 GHz, 26 GHz, and 42 GHz bands. In December 2018 the FCC announced an incentive action in the 37.6 GHz to 38.6 GHz, 38.6 GHz to 40 GHz, and 47.2 GHz to 48.2 GHz. Most other developing countries are undergoing similar considerations of spectrum allocation for 5G use cases.

One of the main reasons that additional spectrum is being made available for 5G uses, is the physical limitations associated with throughput and bandwidth. 4G band plans accounted for between 5 MHz and 20 MHz of bandwidth per channel, where the 5G FR1 standard allows for between 5 MHz and 100 MHz of bandwidth per channel. As bandwidth is directly proportional to maximum throughput, the 5X increase in bandwidth relates to roughly a 5X increase in throughput. Moreover, 3GPP Release 15 established new waveforms and the addition of π/2 BPSK as a modulation method. The additional waveforms are discrete fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM) for FR1 and cyclic prefix OFDM (CP-OFDM) for FR2.

Though RF hardware, technology, and the communications infrastructure are available and capable of meeting some of the requirements of early 5G frequency and performance specifications, the majority of 5G expectations are still beyond currently accessible technologies. These challenges include cost effective hardware with the necessary frequency operation, handheld/mobile integration, and dense and highly distributed networking infrastructure. With 4G LTE services still being deployed throughout the US and other countries, it will likely be several years before 5G services beyond FR1 5G capabilities are viable.

Conclusion
Each new generation of cellular technology has included changes in frequencies bands and operational modes. This is no different with the development of 5G technologies. What is different, however, is the amount of new frequency spectrum being added, and where in the regime of the electromagnetic spectrum these frequencies reside. Moreover, the hunger for greater bandwidth is also leading policy makers and device manufacturers to eek as much performance out of the crowded sub-6 GHz cellular frequency bands with a variety of techniques that aggregate multiple cellular bands and increase single channel bandwidth. Emerging applications, such as the Internet of Things (IoT) and Machine to Machine (M2M) communications are also encouraging industry to investigate a variety of operating modes for 5G to fit the multitude of applications. In many ways, 5G is being designed to become a modular solution to the challenges of universal wireless connectivity.

For decades, the cellular telephone system has continually grown in adoption and has evolved from simple calling and messaging to an enabling technology for universal wireless connectivity. This evolution has continually involved the adoption of additional frequency spectrum for cellular wireless use, and this is no different with upcoming 5G technologies.

However, the now ubiquitous nature of wireless technology in consumer, automotive, industrial and even military/aerospace applications has transformed the potential of cellular wireless technology from an interpersonal communications platform to a highly flexible wireless networking ecosystem. This is evident given the changes in capabilities and frequencies between 4G LTE and upcoming 5G technologies.This article illuminates details regarding the shift in performance, frequency and requirements from 4G LTE to 5G systems.

Emerging Applications Changing Spectrum Use and Cellular Network Performance

Though earlier cellular wireless generations served applications other than mobile broadband, the bulk of 2G, 3G, and now 4G LTE cellular services are designed and dedicated to mobile broadband. The standards and technologies for previous cellular generations have predominantly supported mobile broadband cellular users in urban and suburban regions, with less of an emphasis in rural regions. The goal of 5G technologies, however, goes beyond merely serving mobile broadband, but offers key improvements that enable a much wider range of applications: enhanced mobile broadband (eMBB), ultra-reliable and low latency communications (URLLC), massive machine-type communications (MMC), and fixed wireless access (FWA).

Enhanced Mobile Broadband (eMBB)

Where 5G eMBB differs from 4G mobile broadband are 5G’s extreme data rates and ubiquitous urban coverage goals. With eMBB the IMT-2020 goals are to provide standard that facilitate peak download speeds to 20 Gbps, and reliable user data rates in urban environments of at least 100 Mbps with only 4 ms latency. Though current 4G mobile broadband speeds can reach peak speeds of hundreds of megabits per second, most urban users experience less than 10 Mbps speeds with latencies in the tens of milliseconds. Beyond rapid video downloads, 5G eMBB will enable use cases that open the door to augmented reality and virtual reality applications in real-time, throughout and urban environment.

This performance requires upgrades throughout the cellular networking stack, as well as technology enhancements for handsets. Much of the change in network architecture is currently happening, as major telecom companies are deploying more small cells to enable eMBB performance, where traditional homogeneous macro-cell architectures have proven incapable, especially in densely cluttered urban environments.

Ultra-reliable and Low Latency Communications (URLLC)

Though some areas experience cellular wireless performance that can be considered enterprise grade, most current cellular systems aren’t able to provide the reliability or latency requirements for critical applications, such as autonomous vehicles, mobile healthcare, factory automation, or emergency response. 5G URLLC aims to provide highly reliable, secure, and low latency communications that provide sub-1ms latency communications solid enough for use in applications that could mean life or death.

Enhancing cellular network reliability and reducing latency involves changes with how cellular handset, base station, and networking is done. These enhancements include new waveforms, lower latency hardware, and likely wireless networking approaches that enable frequency-agility, redundancy, and alternative network architecture types than a star network.

Massive Machine-type Communications (MMC)

Most cellular wireless users today are individuals using mobile handsets, but future cellular networks will likely be dominated by Internet of Things (IoT) devices intercommunicating, reporting sensor information, and acting on control data throughout modernized urban areas, factories, industrial installations, and transportation networks. Much, and maybe the majority, of future cellular communications will be between machines, which pose very different requirements than human users.

Dispersed IoT and machine devices are likely to require a very diverse range of communication requirements, making a single one-size-fits-all wireless communication protocol inviable. Hence, the new 5G standards are likely to include adaptable communication protocol methods, so that systems such as battery operated sensors with low-power and low-data rate requirements can use the same network technology as high-data rate and low-latency autonomous robots, for example. Previously cellular generations relied on using specific frequency bands for certain applications, which is less likely to be the solution for future cellular generations as spectrum congestion leads makes each frequency band more valuable.

Fixed Wireless Access (FWA)

Though sparsely used, 3G and 4G cellular networks have supported a range of pseudo-fixed wireless access systems, with hotspots and cellular modems. However, the enhanced data rate and low latency capability of 5G networks enables an attractive business use case of providing FWA to compete with other last-mile internet service. With greater bandwidth and advanced antenna technologies, many experts predict that 5G networks will be able to provide fiber-like performance and enable developed and developing markets with accessible internet and connectivity. Beyond massive multi-input multi-output (mMIMO) and beamforming capable antennas, FWA services also require bandwidth beyond what is available in the sub-6 GHz spectrum driving current cellular networkings. Large amounts of bandwidth, likely exceeding 1 GHz, will be necessary to provide fiber-like service. Hence, 5G cellular networks are including millimeter-wave frequency bands to enable new applications and dramatic increases in data rates compared to previously generations.

5G Frequencies Compared to 4G Frequencies

Early GSM cellular networks operated at 850 MHz and 1900 MHz. 2G and 3G networks change the modulation method but largely used the same portions of the spectrum with reorganized frequency bands. As 3G evolved, additional frequency bands were included as well as spectrum around 2100 MHz. 4G LTE technologies brought it additional spectrum and frequency bands, namely around 600 MHz, 700 MHz, 1.7/2.1 GHz, 2.3 GHz, and 2.5 GHz. All of the previous cellular network frequencies are based on licenses (Table 1).

The 5G frequency band plans are much more complex, as the frequency spectrum for sub-6 GHz 5G spans 450 MHz to 6 GHz, and millimeter-wave 5G frequencies span 24.250 GHz to 52.600 GHz, and also include unlicensed spectrum. Additionally, there may be 5G spectrum in the 5925 to 7150 MHz range and 64 GHz to 86 GHz range. Therefore, 5G will include all previous cellular spectrum and a large amount spectrum in the sub-6 GHz range, and beyond sub- 6 GHz is many times current cellular spectrum (Table 2 and Table 3). The initial 3GPP release of 5G New Radio Non-standalone (5G NR) standards included several sub-6 GHz frequency bands, designated FR1 (Table 2). The second 3GPP 5G release after IMT-2020 will include FR2 frequency bands in the millimeter-wave spectrum (Table 3).

As with previous cellular generations and 3GPP releases, various regions and countries will also likely adopt unique spectrum for 5G uses. The US FCC, for example, is considering opening 5.925 GHz to 6.425 GHz and 6.425 GHz to 7.125 GHz for unlicensed used and is consulting adding mobile broadband capability in the 3.7 GHz to 4.2 GHz spectrum. Currently, the FCC is actioning spectrum in the 27.5 GHz to 28.35 GHz, 24.25 GHz to 24.45 GHz, and 24.75 GHz 25.25 GHz, range for millimeter-wave 5G use. The FCC may also be considering opening 3.7 GHz to 4.2 GHz mid-band frequencies for 5G, and may also be considering opening 4.9 GHz public safety bands for 5G access. Moreover, the FCC may also make additional bands available for 5G in the 2.75 GHz, 26 GHz, and 42 GHz bands. In December 2018 the FCC announced an incentive action in the 37.6 GHz to 38.6 GHz, 38.6 GHz to 40 GHz, and 47.2 GHz to 48.2 GHz. Most other developing countries are undergoing similar considerations of spectrum allocation for 5G use cases.

One of the main reasons that additional spectrum is being made available for 5G uses, is the physical limitations associated with throughput and bandwidth. 4G band plans accounted for between 5 MHz and 20 MHz of bandwidth per channel, where the 5G FR1 standard allows for between 5 MHz and 100 MHz of bandwidth per channel. As bandwidth is directly proportional to maximum throughput, the 5X increase in bandwidth relates to roughly a 5X increase in throughput. Moreover, 3GPP Release 15 established new waveforms and the addition of π/2 BPSK as a modulation method. The additional waveforms are discrete fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM) for FR1 and cyclic prefix OFDM (CP-OFDM) for FR2.

Though RF hardware, technology, and the communications infrastructure are available and capable of meeting some of the requirements of early 5G frequency and performance specifications, the majority of 5G expectations are still beyond currently accessible technologies. These challenges include cost effective hardware with the necessary frequency operation, handheld/mobile integration, and dense and highly distributed networking infrastructure. With 4G LTE services still being deployed throughout the US and other countries, it will likely be several years before 5G services beyond FR1 5G capabilities are viable.

Conclusion

Each new generation of cellular technology has included changes in frequencies bands and operational modes. This is no different with the development of 5G technologies. What is different, however, is the amount of new frequency spectrum being added, and where in the regime of the electromagnetic spectrum these frequencies reside. Moreover, the hunger for greater bandwidth is also leading policy makers and device manufacturers to eek as much performance out of the crowded sub-6 GHz cellular frequency bands with a variety of techniques that aggregate multiple cellular bands and increase single channel bandwidth. Emerging applications, such as the Internet of Things (IoT) and Machine to Machine (M2M) communications are also encouraging industry to investigate a variety of operating modes for 5G to fit the multitude of applications. In many ways, 5G is being designed to become a modular solution to the challenges of universal wireless connectivity.

Table 1

2G, 3G, 4G Frequency Bands in the US
S.N	Cellular Technology in US	Frequency bands in US	Cellular carriers (Providers) in US
1	GSM	850 MHz, 1900 MHz	AT&T( Closure), T-Mobile
2	CDMA (2G, 3G)	800 MHz, 1900 MHz	Verizon, Sprint, US Cellular
3	WCDMA (3G)	850 MHz, 1900 MHz, 2100 MHz	AT&T (850), T Mobile
4	4G LTE	600 MHz (B71)	T-Mobile
		700 MHz (B17, B12, B13)	AT&T, T-Mobile, US Cellular (B12), Verizon (B13)
		850 MHz (B26, B5)	Sprint, US Cellular (B5)
		1.7/ 2.1 GHz AWS (B4)	AT&T, Verizon, T-Mobile
		1.9 GHz (B2, B25)	AT&T, Verizon, T-Mobile, Sprint (B25)
		2.3 GHz (B30)	AT&T
		2.5 GHz ( B41)	AT&T, Sprint

Table 2

5G NR (5G1) Operating Bands Sub-6 GHz
NR Operating Band	Uplink (MHz)		Downlink (MHz)		Duplex Mode
	FUL_low	FUL_high	FDL_low	FDL_high
n1	1920	1980	2110	2170	FDD
n2	1850	1910	1930	1990	FDD
n3	1710	1785	1805	1880	FDD
n5	824	849	869	894	FDD
n7	2500	2570	2620	2690	FDD
n8	880	915	925	960	FDD
n20	832	862	791	821	FDD
n28	703	748	758	803	FDD
n38	2570	2620	2570	2620	TDD
n41	2496	2690	2496	2690	TDD
n50	1432	1517	1432	1517	TDD
n51	1427	1432	1427	1432	TDD
n66	1710	1780	2110	2200	FDD
n70	1695	1710	1995	2020	FDD
n71	663	698	617	652	FDD
n74	1427	1470	1475	1518	FDD
n75	N/A		1432	1517	SDL
n76	N/A		1427	1432	SDL
n78	3300	3800	3300	3800	TDD
n77	3300	4200	3300	4200	TDD
n79	4400	5000	4400	5000	TDD
n80	1710	1785	N/A		SUL
n81	880	915	N/A		SUL
n82	832	862	N/A		SUL
n83	703	748	N/A		SUL
n84	1920	1980	N/A		SUL
n86	1710	1780	N/A		SUL

Table 3

Standalone 5G (Millimeter-wave) Frequencies Bands (FR2)
Band	ƒ (GHz)	Common name	Subset of band	Uplink / Downlink Frequencies (GHz)	Channel bandwidths (MHz)
n257	26			25.50 – 29.50	50, 100, 200, 400
n258	24	K-band		24.25 – 27.50	50, 100, 200, 400
n260	39	Ka-band		37.00 – 40.00	50, 100, 200, 400
n261	28	Ka-band	n257	27.50 – 28.35	50, 100, 200, 400

Table 4

Non-standalone 5G New Radio Waveform and Sub-Carrier Spacing
Generation	UE Transmit Waveform	Modulation	Channel Bandwidth (MHz)	Sub-Carrier Spacing
4G	SC-FDMA	QPSK, 16QAM, 64QAM, 256QAM	5 to 20	15 kHz
5G1 (FR1)	DFT-S-OFDM	π/2 BPSK, QPSK, 16QAM, 64QAM, 256QAM	5 to 50	15 kHz
	DFT-S-OFDM	π/2 BPSK, QPSK, 16QAM, 64QAM, 256QAM	5 to 100	30 kHz, 60 kHz optional
5G2 (FR2)	CP-OFDM	π/2 BPSK, QPSK, 16QAM, 64QAM, 256QAM	5 to 50	15 kHz
	CP-OFDM	π/2 BPSK, QPSK, 16QAM, 64QAM, 256QAM	5 to 100	30 kHz, 60 kHz optional