According to the Ericsson paper [7], LTE will evolve in a way that recognizes its role in providing ubiquitous wide area coverage for mobile users, and 5G networks will incorporate LTE radio access, based on orthogonal frequency division multiplexing (OFDM), along with new

Millimeter wave cells are very small, and they could be deployed mainly in dense urban areas or indoors delivering greater capacity. In the long term, it is expected that all devices that benefit from network connectivity eventually will become connected through M2M commu-

According to Recommendation ITU-R M.2083-0, goals of future development of 5G capabilities are summarized in **Table 1**, which include IMT-2020 capability eight key parameters [1]. Performance requirements must be met but at the same time depend particularly on the used cases or scenario. The key capabilities of IMT-2020 are presented in **Figure 3** compared with

In the enhanced mobile broadband scenario, peak data rate, user-experienced data rate, area traffic capacity, mobility, energy efficiency, and spectrum efficiency all have high importance

User-experienced data rate 100 Mbit/s (for wide area coverage, e.g., in urban and suburban areas) and 1 Gbit/s (for hotspots, e.g., indoor)

quency bands used; spectrum sharing is also possible as a solution.

30 Broadband Communications Networks - Recent Advances and Lessons from Practice

in fiber is needed in order to realize the 5G vision.

in comparison to connection density and latency.

Mobility 500 km/h (e.g., for high-speed trains)

Energy efficiency 100x more than IMT-Advanced Spectrum efficiency 3x more than IMT-Advanced

**Parameter Key value for 5G** Peak data rate 10–20 Gbit/s

Connection density 106 devices/km2

Area traffic capacity 10 Mbit/s/m2

**Table 1.** 5G target capabilities.

Latency 1 ms

air interfaces.

nications in the future.

those of IMT-Advanced.

**3. Characteristics and requirements of IMT-2020**

In some low-latency communications and ultrareliable scenarios, low latency is of the highest importance, e.g., in order to enable the safety critical applications. Such capability would be required for some high mobility uses as well, e.g., in transportation safety, while, e.g., high data rates, might be less important.

The high connection density is needed in the massive machine-type communication scenario to support large number of devices in the network that, e.g., may transmit only occasionally at low bit rate and with zero or very low mobility. A low-cost radio device with long operational lifetime is of great significance for this usage scenario.

### **4. Future possible IMT frequency bands**

In order to encourage increased data traffic capacity and to enable the transmission bandwidths needed to encourage very high data rates, 5G will extend the range of frequency bands used for mobile communications. This includes new radio spectrum below 6 GHz, as well as spectrum in higher frequencies.

For wireless communications, lower frequencies provide better coverage. Currently, almost all countries use spectrum below 6 GHz for IMT systems. Spectrum relevant for 5G wireless access therefore ranges from below 1 GHz up to approximately 100 GHz.

**Table 2.** Spectrum already identified for IMT.

High frequencies, e.g., those above 10 GHz, can only serve as a complement to lower frequencies and will mainly provide additional system capacity with very wide transmission bandwidths for extreme data rates for dense deployments. Spectrum use at lower-frequency bands will remain the backbone for mobile radio communication networks in the 5G era, providing excellent ubiquitous wide area connectivity.

> (CEPT), in author's opinion will also play a significant role for enabling wide coverage for services of next-generation mobile networks in Europe. Frequency bands currently identi-

**Primary allocations to radiocommunication services in RR in ITU regions (including WRC-15 results)**

Spectrum Usage for 5G Mobile Communication Systems and Electromagnetic Compatibility…

fixed-satellite (Earth-to-space), inter-satellite, mobile, radionavigation, space research (space-to-Earth)

fixed-satellite (space-to-Earth), mobile, mobile except aeronautical mobile, mobile-satellite (space-to-Earth), space research (Earth-to-space), space research

24.25–27.5 Earth exploration-satellite (space-to Earth), fixed,

37–40.5 Earth exploration-satellite (Earth-to-space), fixed,

42.5–43.5 Fixed, fixed-satellite (Earth-to-space), mobile except

radionavigation-satellite 81–86 Fixed, fixed-satellite (Earth-to-space), mobile, mobile-

31.8–33.4 Fixed, inter-satellite, radionavigation, space research (deep space) (space-to-Earth)

(space-to-Earth)

**Table 3.** Possible new spectrum for IMT in frequencies above 24 GHz.

47–47.2 Amateur, amateur-satellite

aeronautical mobile, radio astronomy

satellite (space-to-Earth), inter-satellite, mobile, mobile-satellite (space-to-Earth), radionavigation,

satellite (Earth-to-space), radio astronomy

basis in RR 40.5–42.5 Broadcasting, broadcasting-satellite, fixed, fixed-satellite

(space-to-Earth)

45.5–47 Mobile, mobile-satellite, radionavigation, radionavigation-satellite 47.2–50.2 Fixed, fixed-satellite (Earth-to-space), fixed-satellite (space-to-Earth), mobile 50.4–52.6 Fixed, fixed-satellite (Earth-to-space), mobile 66–76 Broadcasting, broadcasting-satellite, fixed, fixed**Comments**

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33

in RR

Frequencies have already allocation to the mobile service on a primary basis

Frequencies may require additional allocation to the mobile service on a primary

The *priority* frequency band suitable for the introduction of 5G use in Europe even before 2020 with wide channel bandwidths (50–100 MHz and more) could be 3400–3800 MHz band, noting that this band is already harmonized for mobile networks in Europe. This frequency band

5G envisages very high data rates, which will need much larger bandwidths than ever before. Those very high data rates may only be found in higher frequency bands (above 6 GHz). To

fied for IMT in the ITU Radio Regulations (RR) are presented in **Table 2**.

has the ability to put Europe at the forefront of the 5G or *pre-*5G deployment.

**4.2. Spectrum above 6 GHz**

**Frequencies to be studied until WRC-19 for possible identification to IMT**

**(GHz)**

#### **4.1. Spectrum below 6 GHz**

Besides achieving high data rates, it is also necessary to guarantee wide area coverage and outdoor to indoor coverage in 5G. Therefore, spectrum below 6 GHz forms a very important part of the 5G spectrum solution. Until now in Europe, more than 1200 MHz of spectrum for mobile broadband in the frequency range from 694 to 3800 MHz was harmonized.

For providing ubiquitous coverage in next-generation (5G) or pre-5G networks, the important role will be of LTE (4G) bands already harmonized below 1 GHz, including particularly the 700 and 800 MHz band, in order to enable nationwide and indoor 5G coverage. The 450 MHz band, which harmonized conditions for LTE use in the band currently is under development in the European Conference of Postal and Telecommunications Administrations

**Table 3.** Possible new spectrum for IMT in frequencies above 24 GHz.

(CEPT), in author's opinion will also play a significant role for enabling wide coverage for services of next-generation mobile networks in Europe. Frequency bands currently identified for IMT in the ITU Radio Regulations (RR) are presented in **Table 2**.

The *priority* frequency band suitable for the introduction of 5G use in Europe even before 2020 with wide channel bandwidths (50–100 MHz and more) could be 3400–3800 MHz band, noting that this band is already harmonized for mobile networks in Europe. This frequency band has the ability to put Europe at the forefront of the 5G or *pre-*5G deployment.

#### **4.2. Spectrum above 6 GHz**

High frequencies, e.g., those above 10 GHz, can only serve as a complement to lower frequencies and will mainly provide additional system capacity with very wide transmission bandwidths for extreme data rates for dense deployments. Spectrum use at lower-frequency bands will remain the backbone for mobile radio communication networks in the 5G era, providing

**World Radiocommunication Conference (WRC)**

450–470 WRC-07 450–457.5 / 460–467.5

470–608 WRC-15 — 614–698 WRC-15 — 694–960 WRC-2000, WRC-07, WRC-12 694–790

32 Broadband Communications Networks - Recent Advances and Lessons from Practice

1427–1518 WRC-15 1427–1518

2300–2400 WRC-07 2300–2400 2500–2690 WRC-2000 2500–2690

3400–3600 WRC-07 3400–3600 3600–3700 WRC-15 3600–3800

3300–3400 WRC-15 —

4800–4990 WRC-15 —

1710–2025 WARC-92, WRC-2000 1710–1785 / 1805–1880

2110–2200 WARC-92 1920–1980 / 2110–2170

**Licensed mobile frequency bands in**

**CEPT countries (MHz)**

790–862

1900–1920

2010–2025

880–915 / 925–960

1920–1980 / 2110–2170

Besides achieving high data rates, it is also necessary to guarantee wide area coverage and outdoor to indoor coverage in 5G. Therefore, spectrum below 6 GHz forms a very important part of the 5G spectrum solution. Until now in Europe, more than 1200 MHz of spectrum for

For providing ubiquitous coverage in next-generation (5G) or pre-5G networks, the important role will be of LTE (4G) bands already harmonized below 1 GHz, including particularly the 700 and 800 MHz band, in order to enable nationwide and indoor 5G coverage. The 450 MHz band, which harmonized conditions for LTE use in the band currently is under development in the European Conference of Postal and Telecommunications Administrations

mobile broadband in the frequency range from 694 to 3800 MHz was harmonized.

excellent ubiquitous wide area connectivity.

**Table 2.** Spectrum already identified for IMT.

**4.1. Spectrum below 6 GHz**

**Frequency bands identified for IMT in the RR (MHz)**

> 5G envisages very high data rates, which will need much larger bandwidths than ever before. Those very high data rates may only be found in higher frequency bands (above 6 GHz). To

deliver higher data rates and lower latency, there is an expectation that new wireless solutions at higher frequencies—millimeter wave (*mmWave*) bands—will be deployed. Therefore, implementation of frequency bands even above 24 GHz remains needed to ensure all the performance targets of 5G, e.g., multi-gigabit per second data rates. Implications of very low-latency drive to millimeter wave deployments with their highly directive antennas and small cell sizes.

The 2015 World Radiocommunication Conference (WRC-15) decided the following frequency bands 24.25–27.5 GHz, 31.8–33.4 GHz, 37–43.5 GHz, 45.5–50.2 GHz, 50.4–52.6 GHz, 66–76 GHz, and 81–86 GHz as presented in **Table 3** to study for possible identification to IMT (aimed for 5G) at WRC-19.

Europe identified 26 GHz as a *pioneer* frequency band for early European harmonization, as it provides over 3 GHz of contiguous spectrum and has the greatest potential to be a globally harmonized band.

The 31.8–33.4 GHz (referred to as 32 GHz) and 40.5–43.5 GHz (referred to as 40 GHz) bands were also identified as priority bands for study in the CEPT.

### **5. Examples of 5G usage scenarios**

According to the recent ITU theoretical assessment, simulations, measurements, technology development, and prototyping described in the Report ITU-R M.2376-0, utilization of bands between 6 and 100 GHz is feasible for studied IMT deployment scenarios and could be considered for the development of IMT for 2020 and beyond [6].

**5.2. Channel bandwidth**

*C* = *B* ⋅ log2(1 + \_\_*S*

**Figure 4.** System deployment architecture proposed for 5G.

capability to implement wide channels.

TDD will play a more important role.

complexity and possible interference issues.

calculated by

For single-input/single-output (SISO) scenario, the maximum capacity of a radio channel can be described by Shannon-Hartley formula. This formula relates the maximum capacity (transmission bit rate) that can be achieved over a given channel to certain noise characteristics and bandwidth. For an *additive white Gaussian noise* of power the *N*, the maximum capacity can be

Spectrum Usage for 5G Mobile Communication Systems and Electromagnetic Compatibility…

where *C* is the maximum capacity of the channel (bits(s)) otherwise known as *Shannon's capacity limit for the given channel*, *B* is the bandwidth of the channel (Hz), *S* is the signal power (W),

It can be perceived that the maximum transmission data rate, at which the information can be transmitted without any error, is limited by the bandwidth, the signal level, and the noise level. With the increase in bandwidth, the noise power also increases; that is why the channel capacity does not become infinite. By using wider channels, increasing the number of anten-

One of the benefits of higher-frequency adaptation for mobile communications is system

In the authors' opinion, to achieve objectives set for future IMT-2020 systems, it is necessary to provide contiguous, broad, and harmonized frequency bands, which will minimize 5G device

In the 5G era, FDD will remain the main duplex scheme for lower-frequency bands. However, for higher-frequency bands—especially above 10 GHz—targeting very dense deployments,

and *N* is the noise power (W). The ratio *S*/*N* is named *signal-to-noise ratio* (SNR) [8].

nas, and reducing interference, it is possible to increase the capacity.

*N*), (1)

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35

It is expected that LTE will develop in a way of providing wide area coverage for mobile users. 5G networks will include LTE access based on OFDM along with new radio interfaces using possibly new techniques, e.g., filter bank multicarrier (FBMC) transmission technique.

### **5.1. IMT-2020 architecture**

Deployment architecture of IMT-2020 can be classified into two architecture types: *stand-alone* or *overlay*. The stand-alone architecture refers to the network deployment consisting of millimeter wave (*mmWave*) small cells. The overlay architecture refers to the network deployment of mmWave small cells developed on top of the existing macro-cell networks (LTE, etc.). In overlay architecture case, the macro-cell layer of the existing 4G mobile communication serves mainly for providing coverage, whereas the mmWave small cell layer should be used to provide capacity [6] as shown in **Figure 4**.

For mmWave small cells explicated using cellular technologies, the typical service range is expected to be around 10 to 200 m under non-line-of-sight (NLOS) circumstances, which is a lot shorter than the range of a cellular macro-cell that can provide several kilometers. The small cells can be deployed both indoors (e.g., femto cells) and outdoors. When deployed outdoors, mmWave small cells are typically deployed at a lower antenna height than a macrocell (on street lamp posts, on building walls, in parks, etc.) and with lower transmit power to cover a targeted area. For mmWave small cell deployment, scenarios can be identified three categories: indoor, hotspot, and outdoor [6].

Spectrum Usage for 5G Mobile Communication Systems and Electromagnetic Compatibility… http://dx.doi.org/10.5772/intechopen.72431 35

**Figure 4.** System deployment architecture proposed for 5G.

### **5.2. Channel bandwidth**

deliver higher data rates and lower latency, there is an expectation that new wireless solutions at higher frequencies—millimeter wave (*mmWave*) bands—will be deployed. Therefore, implementation of frequency bands even above 24 GHz remains needed to ensure all the performance targets of 5G, e.g., multi-gigabit per second data rates. Implications of very low-latency drive to millimeter wave deployments with their highly directive antennas and small cell sizes. The 2015 World Radiocommunication Conference (WRC-15) decided the following frequency bands 24.25–27.5 GHz, 31.8–33.4 GHz, 37–43.5 GHz, 45.5–50.2 GHz, 50.4–52.6 GHz, 66–76 GHz, and 81–86 GHz as presented in **Table 3** to study for possible identification to IMT

Europe identified 26 GHz as a *pioneer* frequency band for early European harmonization, as it provides over 3 GHz of contiguous spectrum and has the greatest potential to be a globally

The 31.8–33.4 GHz (referred to as 32 GHz) and 40.5–43.5 GHz (referred to as 40 GHz) bands

According to the recent ITU theoretical assessment, simulations, measurements, technology development, and prototyping described in the Report ITU-R M.2376-0, utilization of bands between 6 and 100 GHz is feasible for studied IMT deployment scenarios and could be con-

It is expected that LTE will develop in a way of providing wide area coverage for mobile users. 5G networks will include LTE access based on OFDM along with new radio interfaces using possibly new techniques, e.g., filter bank multicarrier (FBMC) transmission technique.

Deployment architecture of IMT-2020 can be classified into two architecture types: *stand-alone* or *overlay*. The stand-alone architecture refers to the network deployment consisting of millimeter wave (*mmWave*) small cells. The overlay architecture refers to the network deployment of mmWave small cells developed on top of the existing macro-cell networks (LTE, etc.). In overlay architecture case, the macro-cell layer of the existing 4G mobile communication serves mainly for providing coverage, whereas the mmWave small cell layer should be used

For mmWave small cells explicated using cellular technologies, the typical service range is expected to be around 10 to 200 m under non-line-of-sight (NLOS) circumstances, which is a lot shorter than the range of a cellular macro-cell that can provide several kilometers. The small cells can be deployed both indoors (e.g., femto cells) and outdoors. When deployed outdoors, mmWave small cells are typically deployed at a lower antenna height than a macrocell (on street lamp posts, on building walls, in parks, etc.) and with lower transmit power to cover a targeted area. For mmWave small cell deployment, scenarios can be identified three

were also identified as priority bands for study in the CEPT.

34 Broadband Communications Networks - Recent Advances and Lessons from Practice

sidered for the development of IMT for 2020 and beyond [6].

**5. Examples of 5G usage scenarios**

to provide capacity [6] as shown in **Figure 4**.

categories: indoor, hotspot, and outdoor [6].

(aimed for 5G) at WRC-19.

**5.1. IMT-2020 architecture**

harmonized band.

For single-input/single-output (SISO) scenario, the maximum capacity of a radio channel can be described by Shannon-Hartley formula. This formula relates the maximum capacity (transmission bit rate) that can be achieved over a given channel to certain noise characteristics and bandwidth. For an *additive white Gaussian noise* of power the *N*, the maximum capacity can be calculated by

$$C = B \cdot \log\_2 \left( 1 + \frac{S}{N} \right) \tag{1}$$

where *C* is the maximum capacity of the channel (bits(s)) otherwise known as *Shannon's capacity limit for the given channel*, *B* is the bandwidth of the channel (Hz), *S* is the signal power (W), and *N* is the noise power (W). The ratio *S*/*N* is named *signal-to-noise ratio* (SNR) [8].

It can be perceived that the maximum transmission data rate, at which the information can be transmitted without any error, is limited by the bandwidth, the signal level, and the noise level. With the increase in bandwidth, the noise power also increases; that is why the channel capacity does not become infinite. By using wider channels, increasing the number of antennas, and reducing interference, it is possible to increase the capacity.

One of the benefits of higher-frequency adaptation for mobile communications is system capability to implement wide channels.

In the authors' opinion, to achieve objectives set for future IMT-2020 systems, it is necessary to provide contiguous, broad, and harmonized frequency bands, which will minimize 5G device complexity and possible interference issues.

In the 5G era, FDD will remain the main duplex scheme for lower-frequency bands. However, for higher-frequency bands—especially above 10 GHz—targeting very dense deployments, TDD will play a more important role.

In author's opinion, 5G wireless access may be realized by the improved LTE systems for existing spectrum in combination with new radio access technologies that primarily target new spectrum [2].

within the radiocommunication sector, and consideration of spectrum for 5G above 24 GHz is

Spectrum Usage for 5G Mobile Communication Systems and Electromagnetic Compatibility…

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37

In the framework of WRC-19 Agenda Item 1.13, identification of frequency bands 24.25–27.5GHz, 31.8–33.4 GHz, 37–43.5 GHz, 45.5–50.2 GHz, 50.4–52.6 GHz, 66–76 GHz, and 81–86 GHz for the future development of IMT will be considered, including possible additional allocations to the

Compatibility studies must be carried out in each frequency band, and each band must balance with the requirement of other existing services and allocations. Any identification of frequency bands for IMT should take into account the use of the bands by other services (to protect existing services) and the evolving needs of these services. WRC-19 Agenda Item 1.13 states to conduct and complete in time for WRC-19 the appropriate sharing and compatibility studies, taking into account the protection of services to which the band is allocated on a primary basis.

Spectrum sharing will be an important element to facilitate the requirements of 5G, and the development of new technological solutions in higher-frequency ranges, such as the more extensive use of MIMO technique, may provide more opportunities for sharing but also chal-

In the future, there may be a need to adapt the harmonized regulatory framework for 5G in the existing mobile frequency bands in Europe (700 MHz, 800 MHz, 900 MHz, 1500 MHz,

Congestion of the radio spectrum is growing with an ongoing rise in the demand for more wireless services. National communications regulators are faced with the challenge of identifying new frequencies for new uses while preventing interference to existing users of the

Interference occurs when a transmission from one system disrupts the reception of signals at the receiver of another nearby system. It can occur between systems operating on the same frequency known as co-channel interference or between systems in frequencies that are close known as adjacent channel or adjacent band interference. It is worth noting that there are also

Co-channel interference is a result of the stronger interfering signal, which affects the victim signal. In adjacent channel interference, there are two main causes of interference: *unwanted*

Unwanted emissions are any off-channel noise of the interfering equipment falling within the receive band of the victim receiver and thus acting as co-channel interference to the wanted

expected to feature heavily through the Resolution of WRC-19 Agenda Item 1.13.

mobile service on a primary basis, in accordance with Resolution 238 (WRC-15) [9].

lenges for National Regulatory Authorities (NRAs).

**7. Electromagnetic compatibility evaluation methods**

other types of interference such as intermodulation [10].

*emissions* and *blocking* or *receiver selectivity* as presented in **Figure 5**.

signal. This sort of interference can only be removed at the source.

1800 MHz, 2.1 GHz, 2.3 GHz, 2.6 GHz).

**7.1. Radio frequency interference**

spectrum.

### **5.3. Antenna technology**

Antennas that can operate well enough in distant frequencies at the same time, e.g., at between 450 MHz, 700 MHz, and 26 GHz, are a difficult task. Therefore, most likely two separate antennas, each operating at the specific frequency band, will be required. The wavelengths above 24 GHz provide a possibility to put more antenna elements in the restricted area. The antenna technology with the increased number of particular antenna elements can be used to provide high beamforming gain. The incremented path loss of above 24 GHz frequency bands can be mitigated by beamforming techniques with exact pointing direction. The phased array beamforming is used to raise the received signal power by using beamforming gain. Greater antenna gains may be achieved applying narrower beams [4].

For 5G communication systems, massive MIMO (*multiple-input and multiple-output*) solutions would be used to compensate additional propagation loss in higher frequencies [2] and to minimize interference. Array antennas should be integrated in the terminals or user equipment. In this case, it should be possible since the transmission wavelengths would become smaller.

### **5.4. 5G development scenarios**

The 5G radio access is based on the evolution of LTE and the other one on New Radio (NR) access. In the LTE-5G, enhancements will continue to enable it to support as many 5G requirements and used cases as possible. Unlike the LTE-5G, the NR-5G is free from backward compatibility requirements and thereby able to introduce more fundamental changes, such as targeting spectrum at high (mmWave) frequencies. However, NR is being designed in a scalable manner so it could eventually be migrated to frequencies that are currently served by LTE.

The process of making LTE-5G involves a variety of enhancements and new features in 3GPP Release 14 and Release 15. The most significant ones are enhancements to user data rates and system capacity with FD MIMO (*full-dimension multiple-input multiple-output*), improved support for unlicensed operations, and latency reduction in both control and user planes. FD MIMO is a technology that arranges the signals transmitted to antennas in the form of virtual beams that are able to power multiple receivers in three dimensions. It is expected that this technology significantly will increase spectrum efficiency.

In authors' opinion, LTE along with NR-5G will continue to play a major role in mobile communications for many years to come.

### **6. Electromagnetic compatibility studies with existent technologies**

The 2019 World Radiocommunication Conference (WRC-19) will take place over 4 weeks, from 28 October to 22 November 2019. The Conference will address a number of questions within the radiocommunication sector, and consideration of spectrum for 5G above 24 GHz is expected to feature heavily through the Resolution of WRC-19 Agenda Item 1.13.

In the framework of WRC-19 Agenda Item 1.13, identification of frequency bands 24.25–27.5GHz, 31.8–33.4 GHz, 37–43.5 GHz, 45.5–50.2 GHz, 50.4–52.6 GHz, 66–76 GHz, and 81–86 GHz for the future development of IMT will be considered, including possible additional allocations to the mobile service on a primary basis, in accordance with Resolution 238 (WRC-15) [9].

Compatibility studies must be carried out in each frequency band, and each band must balance with the requirement of other existing services and allocations. Any identification of frequency bands for IMT should take into account the use of the bands by other services (to protect existing services) and the evolving needs of these services. WRC-19 Agenda Item 1.13 states to conduct and complete in time for WRC-19 the appropriate sharing and compatibility studies, taking into account the protection of services to which the band is allocated on a primary basis.

Spectrum sharing will be an important element to facilitate the requirements of 5G, and the development of new technological solutions in higher-frequency ranges, such as the more extensive use of MIMO technique, may provide more opportunities for sharing but also challenges for National Regulatory Authorities (NRAs).

In the future, there may be a need to adapt the harmonized regulatory framework for 5G in the existing mobile frequency bands in Europe (700 MHz, 800 MHz, 900 MHz, 1500 MHz, 1800 MHz, 2.1 GHz, 2.3 GHz, 2.6 GHz).

### **7. Electromagnetic compatibility evaluation methods**

Congestion of the radio spectrum is growing with an ongoing rise in the demand for more wireless services. National communications regulators are faced with the challenge of identifying new frequencies for new uses while preventing interference to existing users of the spectrum.

### **7.1. Radio frequency interference**

In author's opinion, 5G wireless access may be realized by the improved LTE systems for existing spectrum in combination with new radio access technologies that primarily target

Antennas that can operate well enough in distant frequencies at the same time, e.g., at between 450 MHz, 700 MHz, and 26 GHz, are a difficult task. Therefore, most likely two separate antennas, each operating at the specific frequency band, will be required. The wavelengths above 24 GHz provide a possibility to put more antenna elements in the restricted area. The antenna technology with the increased number of particular antenna elements can be used to provide high beamforming gain. The incremented path loss of above 24 GHz frequency bands can be mitigated by beamforming techniques with exact pointing direction. The phased array beamforming is used to raise the received signal power by using beamforming gain. Greater

For 5G communication systems, massive MIMO (*multiple-input and multiple-output*) solutions would be used to compensate additional propagation loss in higher frequencies [2] and to minimize interference. Array antennas should be integrated in the terminals or user equipment. In this case, it should be possible since the transmission wavelengths would become smaller.

The 5G radio access is based on the evolution of LTE and the other one on New Radio (NR) access. In the LTE-5G, enhancements will continue to enable it to support as many 5G requirements and used cases as possible. Unlike the LTE-5G, the NR-5G is free from backward compatibility requirements and thereby able to introduce more fundamental changes, such as targeting spectrum at high (mmWave) frequencies. However, NR is being designed in a scalable manner so it could eventually be migrated to frequencies that are currently served by LTE. The process of making LTE-5G involves a variety of enhancements and new features in 3GPP Release 14 and Release 15. The most significant ones are enhancements to user data rates and system capacity with FD MIMO (*full-dimension multiple-input multiple-output*), improved support for unlicensed operations, and latency reduction in both control and user planes. FD MIMO is a technology that arranges the signals transmitted to antennas in the form of virtual beams that are able to power multiple receivers in three dimensions. It is expected that this

In authors' opinion, LTE along with NR-5G will continue to play a major role in mobile com-

The 2019 World Radiocommunication Conference (WRC-19) will take place over 4 weeks, from 28 October to 22 November 2019. The Conference will address a number of questions

**6. Electromagnetic compatibility studies with existent technologies**

antenna gains may be achieved applying narrower beams [4].

36 Broadband Communications Networks - Recent Advances and Lessons from Practice

technology significantly will increase spectrum efficiency.

munications for many years to come.

new spectrum [2].

**5.3. Antenna technology**

**5.4. 5G development scenarios**

Interference occurs when a transmission from one system disrupts the reception of signals at the receiver of another nearby system. It can occur between systems operating on the same frequency known as co-channel interference or between systems in frequencies that are close known as adjacent channel or adjacent band interference. It is worth noting that there are also other types of interference such as intermodulation [10].

Co-channel interference is a result of the stronger interfering signal, which affects the victim signal. In adjacent channel interference, there are two main causes of interference: *unwanted emissions* and *blocking* or *receiver selectivity* as presented in **Figure 5**.

Unwanted emissions are any off-channel noise of the interfering equipment falling within the receive band of the victim receiver and thus acting as co-channel interference to the wanted signal. This sort of interference can only be removed at the source.

These studies can be performed using a range of software tools, for example, SEAMCAT for Monte Carlo analysis, which is an open-source software tool. In order to compare both methods, the same radiowave propagation prediction model should be adopted for all three methods.

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39

In some cases, the assumptions used in the studies can be validated through laboratory mea-

If the results of studies show that interference may occur, it may be necessary to investigate different mitigation techniques to minimize the risk of interference. This could include specification of additional filtering to be applied to the transmitter or receiver, additional frequency separation between both systems, and restrictions on the usage of the new system such as limits on maximum transmit power or geographical restrictions on where the new system can be used. In addition, with the emergence of new technologies, new and innovative sharing solutions are being explored, for example, techniques such as geolocation and

This overall process, including the prevention of interference by quantifying the risk through studies and the cure through identifying suitable mitigation, is known as spectrum engineer-

Sharing studies need to have accurate input assumptions in order to produce meaningful and reliable results. Spectrum engineers are working with future technologies where not all the parameters can be defined in advance of the deployment of the new technology. Spectrum

Different interference criteria can be used for interference assessment to the mobile service

The protection criterion for use in sharing and compatibility studies between IMT-Advanced and IMT-2020 and other systems and services irrespective of the number of cells and independent of the number of interferers is I/N value of −6 dB. This criterion applies to interference from a single source or to the aggregate interference from multiple sources of interference. The same protection criterion should be used for both co-channel and adjacent band studies [11, 12]. For the assessment of the interference of LTE and other services in 700 MHz band [13, 14], authors used both of these methods, namely, MCL and Monte Carlo method, and the criterion of *I*/*N* = −6 dB was used for interference assessment to the mobile service. In this assessment the predetermined trigger field strength values also was used. Additionally, some field mea-

Global harmonization of IMT spectrum will be essential for developing 5G. The benefits of spectrum harmonization include facilitating economies of scale, enabling global roaming, reducing

surements of real systems or through field measurements [10].

engineering results can be used to optimize frequency planning.

stations or other services, e.g., C/I, C/(N + I), (N + I)/N, or I/N.

licensed shared access (LSA).

**7.3. Protection criteria for mobile service**

surements were also performed.

**8. Conclusion**

ing [10].

**Figure 5.** Causes of interference: unwanted emissions and blocking.

Blocking, i.e., a strong signal off the receive band of a victim receiver, desensitizes its reception. This sort of interference can only be removed at the victim. In most cases, adoption of power control for the interferer and efficient site engineering can improve the situation.

In practice, both of these can occur simultaneously. Sometimes, it is necessary to improve the design of both the transmitter and receiver to prevent interference, which is becoming increasingly important as the spectrum becomes more congested [10].

#### **7.2. Interference prediction methods**

Interference prediction typically is done through theoretical calculations known as sharing studies, which usually refer to in-band studies, and compatibility studies, which refer to adjacent band studies. Theoretical studies are necessary because it is not always possible to perform measurements on real systems, particularly in cases where the systems are still under development. Two types of studies are commonly used:

*Deterministic* studies based on fixed parameters, using the *minimum coupling loss* (MCL) method. This is a worst-case assessment of interference. The results usually determine the minimum required separation distance (in space or in frequency) between two systems to avoid interference. The MCL approach is relatively straightforward, modeling only a single interferer-victim pair. It provides a result that is spectrally inefficient.

*Statistical* studies based on variable parameters, using the *Monte Carlo* method. This is a more realistic assessment, which takes into account the real-world variation and randomization of certain parameters such as the relative positioning of systems. The result of a Monte Carlo simulation is a measure of system performance—it is commonly a probability of interference for the scenario under investigation, which can be compared against a relevant threshold to determine if the level of interference is considered to be a problem or not. Care must be taken when interpreting a probability of interference. A mobile system operator specifies that a system can provide a system availability of 95%. It is capable of modeling highly complex systems including LTE networks. The result is spectrally efficient but requires careful interpretation.

A mobile system operator specifies that a system can provide a system availability of 95%.

These studies can be performed using a range of software tools, for example, SEAMCAT for Monte Carlo analysis, which is an open-source software tool. In order to compare both methods, the same radiowave propagation prediction model should be adopted for all three methods.

In some cases, the assumptions used in the studies can be validated through laboratory measurements of real systems or through field measurements [10].

If the results of studies show that interference may occur, it may be necessary to investigate different mitigation techniques to minimize the risk of interference. This could include specification of additional filtering to be applied to the transmitter or receiver, additional frequency separation between both systems, and restrictions on the usage of the new system such as limits on maximum transmit power or geographical restrictions on where the new system can be used. In addition, with the emergence of new technologies, new and innovative sharing solutions are being explored, for example, techniques such as geolocation and licensed shared access (LSA).

This overall process, including the prevention of interference by quantifying the risk through studies and the cure through identifying suitable mitigation, is known as spectrum engineering [10].

Sharing studies need to have accurate input assumptions in order to produce meaningful and reliable results. Spectrum engineers are working with future technologies where not all the parameters can be defined in advance of the deployment of the new technology. Spectrum engineering results can be used to optimize frequency planning.

### **7.3. Protection criteria for mobile service**

Different interference criteria can be used for interference assessment to the mobile service stations or other services, e.g., C/I, C/(N + I), (N + I)/N, or I/N.

The protection criterion for use in sharing and compatibility studies between IMT-Advanced and IMT-2020 and other systems and services irrespective of the number of cells and independent of the number of interferers is I/N value of −6 dB. This criterion applies to interference from a single source or to the aggregate interference from multiple sources of interference. The same protection criterion should be used for both co-channel and adjacent band studies [11, 12].

For the assessment of the interference of LTE and other services in 700 MHz band [13, 14], authors used both of these methods, namely, MCL and Monte Carlo method, and the criterion of *I*/*N* = −6 dB was used for interference assessment to the mobile service. In this assessment the predetermined trigger field strength values also was used. Additionally, some field measurements were also performed.

### **8. Conclusion**

Blocking, i.e., a strong signal off the receive band of a victim receiver, desensitizes its reception. This sort of interference can only be removed at the victim. In most cases, adoption of power control for the interferer and efficient site engineering can improve the

In practice, both of these can occur simultaneously. Sometimes, it is necessary to improve the design of both the transmitter and receiver to prevent interference, which is becoming increas-

Interference prediction typically is done through theoretical calculations known as sharing studies, which usually refer to in-band studies, and compatibility studies, which refer to adjacent band studies. Theoretical studies are necessary because it is not always possible to perform measurements on real systems, particularly in cases where the systems are still under

*Deterministic* studies based on fixed parameters, using the *minimum coupling loss* (MCL) method. This is a worst-case assessment of interference. The results usually determine the minimum required separation distance (in space or in frequency) between two systems to avoid interference. The MCL approach is relatively straightforward, modeling only a single

*Statistical* studies based on variable parameters, using the *Monte Carlo* method. This is a more realistic assessment, which takes into account the real-world variation and randomization of certain parameters such as the relative positioning of systems. The result of a Monte Carlo simulation is a measure of system performance—it is commonly a probability of interference for the scenario under investigation, which can be compared against a relevant threshold to determine if the level of interference is considered to be a problem or not. Care must be taken when interpreting a probability of interference. A mobile system operator specifies that a system can provide a system availability of 95%. It is capable of modeling highly complex systems including LTE networks. The result is spectrally efficient

A mobile system operator specifies that a system can provide a system availability of 95%.

ingly important as the spectrum becomes more congested [10].

**Figure 5.** Causes of interference: unwanted emissions and blocking.

38 Broadband Communications Networks - Recent Advances and Lessons from Practice

development. Two types of studies are commonly used:

interferer-victim pair. It provides a result that is spectrally inefficient.

**7.2. Interference prediction methods**

but requires careful interpretation.

situation.

Global harmonization of IMT spectrum will be essential for developing 5G. The benefits of spectrum harmonization include facilitating economies of scale, enabling global roaming, reducing equipment design complexity, improving spectrum efficiency, and potentially reducing cross border interference. 5G mobile communication systems will require frequencies for their development and usage. Frequencies below 6 GHz are very valuable because of its optimum radio wave propagation, especially frequencies below 1 GHz. The results of the present study have shown that implementation of frequency bands even above 24 GHz remains needed to ensure all the performance targets of 5G, e.g., multigigabit per second data rates. In the authors' opinion, for the deliberative development of IMT systems, it is necessary to timely provide wide and contiguous spectrum resources for implementation of new technologies and services.

[5] Ancans A, Bogdanovs N, Petersons E, Ancans G. Evaluation of Wi-Fi and LTE integrated channel performance with different hardware implementation for moving objects. ICTE

Spectrum Usage for 5G Mobile Communication Systems and Electromagnetic Compatibility…

http://dx.doi.org/10.5772/intechopen.72431

41

[6] Technical feasibility of IMT in bands above 6 GHz. Report ITU-R M.2376-0, July 2015

[7] 7G. Radio Access. Ericsson White paper, April 2016. [Online]. Available: https://www.

[8] Saunders SR, Zavala AA. Antennas and Propagation for Wireless Communication

[9] Resolution 238 (WRC-15). Studies on Frequency-Related Matters for International Mobile Telecommunications Identification Including Possible Additional Allocations to the Mobile Services on a Primary Basis in Portion(S) of the Frequency Range between 24.25 and 86 GHz for the Future Development of International Mobile Telecommunications for 2020 and beyond. Switzerland, Geneva: International Telecommunications Union; 2015

[10] A comparison of the minimum coupling loss method, enhanced minimum coupling loss method, and the Monte-Carlo simulation. ERC Report 101, Menton, May 1999

[11] Characteristics of terrestrial IMT-Advanced systems for frequency sharing/interference

[12] Characteristics of terrestrial IMT systems for frequency sharing/interference analyses in the frequency range between 24.25 GHz and 86 GHz. SWG Work for TG 5/1, Revision 3

[13] Radio Regulations. International Telecommunications Union (ITU), vol. 1 (articles edited

[14] Ancans G, Bobrovs V, Ivanovs G. Frequency arrangement for 700 MHz band. Latvian

Journal of Physics and Technical Sciences. February 2015;**52**(1):63

2016, Procedia Computer Science. 2017;**104**:493-500

ericsson.com/res/docs/whitepapers/wp-5g.pdf

Systems. 2nd ed. John Wiley & Sons Ltd.; 2007

analyses. Report ITU-R M.2292-0, December 2013

to Document 5D/TEMP/265-E, 22-02-2017

in 2016), 2016

It is important to note that the properties of higher-frequency bands, such as shorter wavelength, would better enable the use of advanced antenna systems including MIMO and beamforming techniques in supporting enhanced broadband.

The electromagnetic compatibility between LTE and different existent technologies in 700 MHz band authors was evaluated with different methods: MCL method, Monte Carlo method, and predetermined trigger field strength values; some field measurements were also done. According to results of electromagnetic evaluation, additional mitigation techniques were proposed in order to assure the compatibility between considered radio systems. Similar electromagnetic compatibility evaluation methods and approach can be also applied for IMT-2020 studies in frequencies above 24 GHz.

The results obtained within the framework of the research can be used by National Regulatory Authorities, equipment manufacturers, mobile operators, researchers, and other interested parties when planning 4G and 5G mobile services.

### **Author details**

Guntis Ancans\* and Vjaceslavs Bobrovs

\*Address all correspondence to<EMAIL_ADDRESS>
Institute of Telecommunications, Riga Technical University, Riga, Latvia

### **References**

[5] Ancans A, Bogdanovs N, Petersons E, Ancans G. Evaluation of Wi-Fi and LTE integrated channel performance with different hardware implementation for moving objects. ICTE 2016, Procedia Computer Science. 2017;**104**:493-500

equipment design complexity, improving spectrum efficiency, and potentially reducing cross border interference. 5G mobile communication systems will require frequencies for their development and usage. Frequencies below 6 GHz are very valuable because of its optimum radio wave propagation, especially frequencies below 1 GHz. The results of the present study have shown that implementation of frequency bands even above 24 GHz remains needed to ensure all the performance targets of 5G, e.g., multigigabit per second data rates. In the authors' opinion, for the deliberative development of IMT systems, it is necessary to timely provide wide and contiguous spectrum resources for implementation of new technologies and services.

It is important to note that the properties of higher-frequency bands, such as shorter wavelength, would better enable the use of advanced antenna systems including MIMO and beam-

The electromagnetic compatibility between LTE and different existent technologies in 700 MHz band authors was evaluated with different methods: MCL method, Monte Carlo method, and predetermined trigger field strength values; some field measurements were also done. According to results of electromagnetic evaluation, additional mitigation techniques were proposed in order to assure the compatibility between considered radio systems. Similar electromagnetic compatibility evaluation methods and approach can be also applied for IMT-

The results obtained within the framework of the research can be used by National Regulatory Authorities, equipment manufacturers, mobile operators, researchers, and other interested

[1] IMT Vision – Framework and overall objectives of the future development of IMT for

[2] Ancans G, Bobrovs V, Ancans A, Kalibatiene D. Spectrum Considerations for 5G Mobile Communication Systems. ICTE 2016. Procedia Computer Science. 2017;**104**:509-516 [3] 5G Automotive Vision. P. 36, 20-10-2015. [Online]. Available: https://5g–ppp.eu/wp-content/uploads/2014/02/3G.-PPP-White-Paper-on-Automotive-Vertical-Sectors.pdf

[4] Future spectrum requirements estimate for terrestrial IMT. Report ITU-R M.2290-0,

forming techniques in supporting enhanced broadband.

40 Broadband Communications Networks - Recent Advances and Lessons from Practice

2020 studies in frequencies above 24 GHz.

Guntis Ancans\* and Vjaceslavs Bobrovs

pp. 10-14, December 2013

**Author details**

**References**

parties when planning 4G and 5G mobile services.

\*Address all correspondence to<EMAIL_ADDRESS>
Institute of Telecommunications, Riga Technical University, Riga, Latvia

2020 and beyond. Recommendation ITU-R M.2083-0, September 2015

**Chapter 4**

Provisional chapter

**5G Backhaul: Requirements, Challenges, and Emerging**

DOI: 10.5772/intechopen.78615

5G is the next generation cellular networks which is expected to quench the ever-ending thirst of data rates and interconnect billions of smart devices to support not only human centric traffic, but also machine centric traffic. Recent research and standardization work have been addressing requirements and challenges from radio perspective (e.g., new spectrum allocation, network densification, massive multiple-input-multiple-output antenna, carrier aggregation, inter-cell interference mitigation techniques, and coordinated multipoint processing). In addition, a new network bottleneck has emerged: the backhaul network which will allow to interconnect and support billions of devices from the core network. Up to 4G cellular networks, the major challenges to meet the backhaul requirements were capacity, availability, deployment cost, and long-distance reach. However, as 5G network capabilities and services added to 4G cellular networks, the backhaul network would face two additional challenges that include ultralow latency (i.e., 1 ms) requirements and ultradense nature of the network. Due to the dense small cell deployment and heavy traffic cells in 5G, 5G backhaul network will need to support hundreds of gigabits of traffic from the core network and today's cellular backhaul networks are infeasible to meet these requirements in terms of capacity, availability, latency, energy, and cost efficiency. This book chapter first introduce the mobile backhaul network perspective for 2G, 3G, and 4G networks. Then, outlines the backhaul requirements of 5G networks, and describes the impact

Keywords: 5G, mobile backhaul network, wired backhaul, wireless backhaul, microwave,

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and eproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

5G Backhaul: Requirements, Challenges, and Emerging

**Technologies**

Abstract

Technologies

Md Maruf Ahamed and Saleh Faruque

Md Maruf Ahamed and Saleh Faruque

on current mobile backhaul networks.

millimeter wave, free space optics

http://dx.doi.org/10.5772/intechopen.78615

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

#### **5G Backhaul: Requirements, Challenges, and Emerging Technologies** 5G Backhaul: Requirements, Challenges, and Emerging Technologies

DOI: 10.5772/intechopen.78615

Md Maruf Ahamed and Saleh Faruque Md Maruf Ahamed and Saleh Faruque

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.78615

#### Abstract

5G is the next generation cellular networks which is expected to quench the ever-ending thirst of data rates and interconnect billions of smart devices to support not only human centric traffic, but also machine centric traffic. Recent research and standardization work have been addressing requirements and challenges from radio perspective (e.g., new spectrum allocation, network densification, massive multiple-input-multiple-output antenna, carrier aggregation, inter-cell interference mitigation techniques, and coordinated multipoint processing). In addition, a new network bottleneck has emerged: the backhaul network which will allow to interconnect and support billions of devices from the core network. Up to 4G cellular networks, the major challenges to meet the backhaul requirements were capacity, availability, deployment cost, and long-distance reach. However, as 5G network capabilities and services added to 4G cellular networks, the backhaul network would face two additional challenges that include ultralow latency (i.e., 1 ms) requirements and ultradense nature of the network. Due to the dense small cell deployment and heavy traffic cells in 5G, 5G backhaul network will need to support hundreds of gigabits of traffic from the core network and today's cellular backhaul networks are infeasible to meet these requirements in terms of capacity, availability, latency, energy, and cost efficiency. This book chapter first introduce the mobile backhaul network perspective for 2G, 3G, and 4G networks. Then, outlines the backhaul requirements of 5G networks, and describes the impact on current mobile backhaul networks.

Keywords: 5G, mobile backhaul network, wired backhaul, wireless backhaul, microwave, millimeter wave, free space optics

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and eproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

### 1. Introduction

During the last few decades, mobile communication has evolved significantly from early wireless voice systems to today's intelligent communication systems [1, 2]. With the advancement of each generation, the mobile communication systems become more sophisticated and unleashed new consumer services that support countless mobile applications used by billions of people around the world, shown in Figure 1 [1–3]. In 2000, when 3G brought us the wireless data, the consumers got access to the internet anytime and anywhere they go [2]. This mobile broadband network with a combination of the innovation of smartphone technologies brought a significant change of mobile internet experience where users can access their email, social media, music, high definition video streaming, online gaming, and many more, which we see today as the app-centric interface [4].

requirements are discussed in [7]. Here are the two most significant trends of 5G services are

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• Everything will be connected to the mobile network wirelessly that will enable the billions of smart devices interconnected autonomously while ensuring the security and privacy [8]. 5G network will enable emerging services that include remote monitoring and realtime control of a diverse range of smart devices, which will support machine-to-machine (M2M) services and Internet of Things (IoT), such as connected cars, connected homes, moving robots and sensors [6, 8–10]. According to Cisco VNI Mobile 2017, the most noticeable growth will occur in M2M connections. The number of M2M connection will reach 3.3 billion by 2021, which is 29% of the total devices and connections and it was only 10% in 2016 [5]. Another mobile traffic forecast by UMTS presented that the total number of connected IoT devices will reach to 50 billion by 2020 which was only 12.5 billion in

• 5G networks will deliver richer content in real time ensuring the safety and security that will make the wireless services more extensive in our everyday life. Some example of emerging services may include high resolution video streaming (4K), media rich social network services, augmented reality, and road safety [6]. According to Cisco mobile data traffic forecast, the maximum mobile data traffic will be generated by video-based mobile application, which is going to be 72% of mobile data traffic by 2019 compared to 55% in

It is clear that the future mobile network (i.e., 5G) will no longer human centric, it will be more on machine centric which will interconnect billions of smart devices to the mobile network. According to Cisco, smart devices are those that have advanced computing and multimedia capabilities with a minimum of 3G network connectivity [5]. Globally the growth of smart devices will reach 82% by 2021 and some regions it will reach 99% by 2021 (e.g., North America). The main impact of this growth will be on mobile data traffic because a smart device generates much higher traffic compared to non-smart device. According to Cisco forecast, a smart device generated 13 times more traffic compared to non-smart device in 2016 and by 2021 a smart device will be able to generate 21 times more traffic [5]. According to another mobile traffic forecast by Cisco, the expected growth will reach 24.3 Exabytes per month by 2019 which was only 2.5 Exabytes in 2014 [12]. This ever-increasing traffic growth becomes the key driver for the evolution of next generation mobile networks, called 5G, envisioned for the year 2020 [13, 14]. The key requirements of 5G network include, extreme broadband delivery, ultrarobust network, ultralow latency (i.e., less than 1 ms latency) connectivity, and support

To bring the 5G network in reality, a simple upgrade of mobile network will not be enough where we just add new spectrum and enhance the capacity or use advanced radio technology. It will need to upgrade from the system and architecture levels down to the physical layer [15]. Although some research and standardization work addressing the corresponding challenges from radio perspective (e.g., new spectrum exploration, carrier aggregation, network densification, massive multiple-input-multiple-output, and inter-cell interference mitigation techniques) but there is a new challenge has emerged: the backhaul [16–18]. Because in 5G

massive smart devices for the human and for the IoT services [15].

discussed below [6]:

2010 [5].

2014 [5, 11].

Due to the advancement of technologies, mobile devices getting smarter every day in terms of advanced computing and multimedia capabilities that supports a wide range of applications and services (e.g., high quality image transfer, ultrahigh definition video streaming, live video games, and cloud resources) [5, 6]. Therefore, more and more users are expecting to have the same quality of internet experience anytime, and everywhere they go. These trends will even more pronounced when 5G network becomes available with intelligent network capabilities and numerous services. 5G network will extend the wireless connectivity beyond the people, to support the connectivity for everything that may benefit from being connected that might include everything from personal belongings, household appliances, to medical equipment, and everything in between [1]. Numerous 5G network use cases, services and network

Figure 1. The evolution of mobile standards [3].

requirements are discussed in [7]. Here are the two most significant trends of 5G services are discussed below [6]:

1. Introduction

today as the app-centric interface [4].

Figure 1. The evolution of mobile standards [3].

During the last few decades, mobile communication has evolved significantly from early wireless voice systems to today's intelligent communication systems [1, 2]. With the advancement of each generation, the mobile communication systems become more sophisticated and unleashed new consumer services that support countless mobile applications used by billions of people around the world, shown in Figure 1 [1–3]. In 2000, when 3G brought us the wireless data, the consumers got access to the internet anytime and anywhere they go [2]. This mobile broadband network with a combination of the innovation of smartphone technologies brought a significant change of mobile internet experience where users can access their email, social media, music, high definition video streaming, online gaming, and many more, which we see

44 Broadband Communications Networks - Recent Advances and Lessons from Practice

Due to the advancement of technologies, mobile devices getting smarter every day in terms of advanced computing and multimedia capabilities that supports a wide range of applications and services (e.g., high quality image transfer, ultrahigh definition video streaming, live video games, and cloud resources) [5, 6]. Therefore, more and more users are expecting to have the same quality of internet experience anytime, and everywhere they go. These trends will even more pronounced when 5G network becomes available with intelligent network capabilities and numerous services. 5G network will extend the wireless connectivity beyond the people, to support the connectivity for everything that may benefit from being connected that might include everything from personal belongings, household appliances, to medical equipment, and everything in between [1]. Numerous 5G network use cases, services and network

It is clear that the future mobile network (i.e., 5G) will no longer human centric, it will be more on machine centric which will interconnect billions of smart devices to the mobile network. According to Cisco, smart devices are those that have advanced computing and multimedia capabilities with a minimum of 3G network connectivity [5]. Globally the growth of smart devices will reach 82% by 2021 and some regions it will reach 99% by 2021 (e.g., North America). The main impact of this growth will be on mobile data traffic because a smart device generates much higher traffic compared to non-smart device. According to Cisco forecast, a smart device generated 13 times more traffic compared to non-smart device in 2016 and by 2021 a smart device will be able to generate 21 times more traffic [5]. According to another mobile traffic forecast by Cisco, the expected growth will reach 24.3 Exabytes per month by 2019 which was only 2.5 Exabytes in 2014 [12]. This ever-increasing traffic growth becomes the key driver for the evolution of next generation mobile networks, called 5G, envisioned for the year 2020 [13, 14]. The key requirements of 5G network include, extreme broadband delivery, ultrarobust network, ultralow latency (i.e., less than 1 ms latency) connectivity, and support massive smart devices for the human and for the IoT services [15].

To bring the 5G network in reality, a simple upgrade of mobile network will not be enough where we just add new spectrum and enhance the capacity or use advanced radio technology. It will need to upgrade from the system and architecture levels down to the physical layer [15]. Although some research and standardization work addressing the corresponding challenges from radio perspective (e.g., new spectrum exploration, carrier aggregation, network densification, massive multiple-input-multiple-output, and inter-cell interference mitigation techniques) but there is a new challenge has emerged: the backhaul [16–18]. Because in 5G networks, the ultradense and heavy traffic cells will need to support hundreds of gigabits of traffic from the core network through backhaul and today's cellular system architecture is infeasible to meet this extreme requirement in terms of capacity, availability, latency, energy, and cost efficiency [16, 19].

phone user) with the mobile networks (shown in Figure 2). In Figure 2, UE refers to end user, eNodeB refers to cell or cell site or base stations. Each user data is added with other components of the backhaul traffic (shown in Figure 3), to calculate the single eNodeB transport provisioning and then aggregate with all other eNodeB's traffic before it connects with the core

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It is found that the capacity requirements on the transmission network to support the backhaul traffic from the core network is raises with the evolution of mobile/cellular networks [23]. Cost and reliability always been a concern and major challenges for cellular network operators and there is no magic solution to the demand [19]. This section describes, how the mobile backhaul

A typical GSM (Global System for Mobile Communications) network architecture is shown in Figure 4, where the BTS (base station transceivers) are located at the cell site and provide the control and radio air interface for each cell. The BSC (Base station controllers) provides control

network evolve with the evolution of each mobile network (e.g., 2G, 3G, and LTE).

2.1. Typical GSM, 3G, and LTE Network Overview

Figure 2. Mobile backhaul network of LTE (long-term evolution) [26].

Figure 3. Components of backhaul traffic [26].

network.

A details survey about the evolution of mobile backhaul solution from 2G to 3G networks and from 3G to 4G networks are presented in [20, 21], respectively. The hybrid of millimeter wave and optical backhaul solution is proposed in [22] where the software-defined backhaul resource manager is proposed as a novel software defined networking (SDN) approach for realizing high utilization of the backhaul network capacity in a fair and dynamic way, while providing better end-to-end user quality of experience (QoE). Also, [23] provides another hybrid solution that combines an optical laser (through free space) and millimeter-wave radio to provide a combination of guaranteed high capacity, extended reach, and high availability with affordable cost.

If given a choice, fiber always remains the first backhaul choice for service provider due to its inhibitive bandwidths more than 10 Gbps and allowed maximum latency of hundreds of microseconds [16, 23]. But, laying fiber to connect all the cells to the core is not possible in some cases due to the availability problem and the deployment cost is high as well. In addition, fiber deployment, even when it is feasible can take several months [4, 23]. Since the massive deployment of small cells will be the key techniques for 5G networks and the backhaul requirements of the small cells can significantly vary with the small cell location, the fiber cannot be the optimal approach for 5G backhaul solution [23–25]. On the other hand wireless backhauling (e.g., microwave and millimeter wave) becomes popular due to its availability, deployment time and cost-effective approach [24]. But the weather condition and multipath propagation have significant impact on microwave and millimeter-wave radio systems which can affect the transmission performance. So it is obvious that there will no unique backhaul solution for 5G networks. The backhaul evolution for 5G networks will include both wired and wireless backhaul solution [23].

The contributions of this book chapter are listed below:

### 2. Introduction to mobile backhaul network and evolution

The mobile backhaul network connects radio access network air interfaces at the cell sites to the inner core network which ensures the network connectivity of the end user (e.g., mobile phone user) with the mobile networks (shown in Figure 2). In Figure 2, UE refers to end user, eNodeB refers to cell or cell site or base stations. Each user data is added with other components of the backhaul traffic (shown in Figure 3), to calculate the single eNodeB transport provisioning and then aggregate with all other eNodeB's traffic before it connects with the core network.

It is found that the capacity requirements on the transmission network to support the backhaul traffic from the core network is raises with the evolution of mobile/cellular networks [23]. Cost and reliability always been a concern and major challenges for cellular network operators and there is no magic solution to the demand [19]. This section describes, how the mobile backhaul network evolve with the evolution of each mobile network (e.g., 2G, 3G, and LTE).

### 2.1. Typical GSM, 3G, and LTE Network Overview

networks, the ultradense and heavy traffic cells will need to support hundreds of gigabits of traffic from the core network through backhaul and today's cellular system architecture is infeasible to meet this extreme requirement in terms of capacity, availability, latency, energy,

46 Broadband Communications Networks - Recent Advances and Lessons from Practice

A details survey about the evolution of mobile backhaul solution from 2G to 3G networks and from 3G to 4G networks are presented in [20, 21], respectively. The hybrid of millimeter wave and optical backhaul solution is proposed in [22] where the software-defined backhaul resource manager is proposed as a novel software defined networking (SDN) approach for realizing high utilization of the backhaul network capacity in a fair and dynamic way, while providing better end-to-end user quality of experience (QoE). Also, [23] provides another hybrid solution that combines an optical laser (through free space) and millimeter-wave radio to provide a combination of guaranteed high capacity, extended reach, and high availability

If given a choice, fiber always remains the first backhaul choice for service provider due to its inhibitive bandwidths more than 10 Gbps and allowed maximum latency of hundreds of microseconds [16, 23]. But, laying fiber to connect all the cells to the core is not possible in some cases due to the availability problem and the deployment cost is high as well. In addition, fiber deployment, even when it is feasible can take several months [4, 23]. Since the massive deployment of small cells will be the key techniques for 5G networks and the backhaul requirements of the small cells can significantly vary with the small cell location, the fiber cannot be the optimal approach for 5G backhaul solution [23–25]. On the other hand wireless backhauling (e.g., microwave and millimeter wave) becomes popular due to its availability, deployment time and cost-effective approach [24]. But the weather condition and multipath propagation have significant impact on microwave and millimeter-wave radio systems which can affect the transmission performance. So it is obvious that there will no unique backhaul solution for 5G networks. The backhaul evolution for 5G networks will

• First, this chapter provides a brief introduction of mobile backhaul network and the

• Second, provides a comprehensive overview of backhaul requirements of 5G networks

• Finally, it outlines the existing mobile backhaul solutions (i.e., wired and wireless) and list their features, benefits, drawbacks, application areas and deployment challenges.

The mobile backhaul network connects radio access network air interfaces at the cell sites to the inner core network which ensures the network connectivity of the end user (e.g., mobile

2. Introduction to mobile backhaul network and evolution

and cost efficiency [16, 19].

with affordable cost.

include both wired and wireless backhaul solution [23]. The contributions of this book chapter are listed below:

evolution of mobile backhaul network.

and highlight the potential challenges.

A typical GSM (Global System for Mobile Communications) network architecture is shown in Figure 4, where the BTS (base station transceivers) are located at the cell site and provide the control and radio air interface for each cell. The BSC (Base station controllers) provides control

Figure 2. Mobile backhaul network of LTE (long-term evolution) [26].

Figure 3. Components of backhaul traffic [26].

Figure 4. Typical GSM network with wireless interface requirements [27].

over multiple cell sites and multiple base station transceivers. The base station controllers can be located in a separate office or co-located at the mobile switching center (MSC).

Another objective of the LTE standards was to flatten and simplify the network architecture. This resulted in pushing more intelligence into the radios (eNodeB) and elimination of the radio controllers as a separate device. In effect, the radio controller function has been distributed into

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Figure 5. Typical 3G network with wireless interface requirements [27].

Figure 6. Typical LTE network with wireless interface requirements [28].

There are standard interfaces developed by the wireless industry for interconnecting these devices, so they could deploy interoperable systems from multiple vendors. These physical interfaces define the wireless backhaul transport services and requirements. Thus, a basic understanding of these interfaces is very important. Some standard interfaces for GSM network are listed below [27]:

Although the functions of these devices are similar, the 3GPP wireless standards body adopted slightly different names for the functional nodes and logical interfaces for UMTS (3G) networks, shown in Figure 5. But, historically the 2G/3G wireless standards were based on T1 (TDM) physical interfaces for interconnection between these devices because of the wide availability of T1 copper, fiber, and microwave services [28].

T1 physical interfaces has driven mobile backhaul transport requirements for 2G/3G wireless standards, but 4G wireless standards (i.e., LTE: Long-Term Evolution) are based on entirely new packet-based architecture, including the use of Ethernet physical interfaces for interconnection between the various functional elements, shown in Figure 6.

Figure 5. Typical 3G network with wireless interface requirements [27].

over multiple cell sites and multiple base station transceivers. The base station controllers can

There are standard interfaces developed by the wireless industry for interconnecting these devices, so they could deploy interoperable systems from multiple vendors. These physical interfaces define the wireless backhaul transport services and requirements. Thus, a basic understanding of these interfaces is very important. Some standard interfaces for GSM net-

• Abis: the Abis interface connects the base station transceivers to base station controllers. • A: the A interface in Figure 2 connects the base station controller to the mobile switching

• Gb: voice services continue over the A interface, while data services are handled over the

Although the functions of these devices are similar, the 3GPP wireless standards body adopted slightly different names for the functional nodes and logical interfaces for UMTS (3G) networks, shown in Figure 5. But, historically the 2G/3G wireless standards were based on T1 (TDM) physical interfaces for interconnection between these devices because of the wide

T1 physical interfaces has driven mobile backhaul transport requirements for 2G/3G wireless standards, but 4G wireless standards (i.e., LTE: Long-Term Evolution) are based on entirely new packet-based architecture, including the use of Ethernet physical interfaces for intercon-

availability of T1 copper, fiber, and microwave services [28].

nection between the various functional elements, shown in Figure 6.

be located in a separate office or co-located at the mobile switching center (MSC).

Figure 4. Typical GSM network with wireless interface requirements [27].

48 Broadband Communications Networks - Recent Advances and Lessons from Practice

work are listed below [27]:

center.

Gb interface.

Another objective of the LTE standards was to flatten and simplify the network architecture. This resulted in pushing more intelligence into the radios (eNodeB) and elimination of the radio controllers as a separate device. In effect, the radio controller function has been distributed into

Figure 6. Typical LTE network with wireless interface requirements [28].

even some of which are unimagined today. To fulfill the demand of fully mobile and connected society can be characterized by the tremendous increase in the number of connectivity and traffic volume density [29]. According to Nokia, the number of connecting devices per mobile users will be ten to one hundred that includes, mobile phone, laptop, tablet, smart watch to smart shirts [11]. In addition, the number of connected machines and sensor devices in the industry and public infrastructure will increase. According to Ceragon, the forecasted capacity increase could be 1000 compared to the capacity density in current 4G/4.5G networks [30, 31]. So, it is obvious that the evolution of 5G networks from LTE/LTE-A will need higher capacity backhaul links per cell site: while LTE/LTE-A networks need hundreds of Mbps, 5G network

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Availability is the major consideration for any backhaul networks, if the backhaul services are not in operation the system performance are negatively affected. In case of fiber systems, if there is any interruption of current path, the systems will automatically switch to the protection path within <50 ms [23]. Even in the wireless backhaul (e.g., microwave and millimeter wave), the backhaul link can be affected by multipath propagation and bad weaher condition. To overcome this, adaptive modulation technique is used that lowers the line rates to maintain the availability. Although the 5G network requirements is not standard yet, but to provide the expected new services such as autonomous vehicle/autonomous driving, tactile internet, and many machine to machine applications need high availability and very

Cellular network provider has to spend billions of dollars each year to acquire wireless spectrum for building excellent network coverage [23]. Since dense small cell deployment will be the key for 5G networks to support 1000 times more capacity, the cost efficient backhaul solution for the small will be a major challenge. An application specific traffic-engineering model needs to be formulated so that both customers and service providers can be happy.

Reach defines how far a cell site can get backhaul support from the core network with the required quality of service. Long distance reach is always a big issue for the backhaul network in terms of cost and additional equipment (e.g., total deployment cost of fiber backhaul will increase with the distance) [23]. Typically, cell sites are interconnected in a hierarchical mesh and all the traffics are transported back to an aggregation point (sometimes-called super cell) where all the traffics are aggregated and transport to the core network. Due to the dense small cell deployment in the 5G networks, massive backhaul traffic will be aggregated at the super cell that can create congestion and can even collapse the backhaul networks [19]. Therefore,

long distance reach will be a big challenge for the 5G backhaul network.

will need to support tens of Gbps, shown in Figure 1.

3.2. Availability

low latency [30].

3.3. Deployment cost requirements

3.4. Long distance reach requirements

Table 1. Wireless capacity requirements for 2G, 3G and LTE [27, 28].

each eNodeB radio. So, the resultant network is indeed much simpler and flatter, with far fewer functional devices.

From a mobile backhaul perspective: most cell sites will continue to support GSM 2G and UMTS 3G networks for many years, the addition of LTE means backhaul transport carriers need to implement systems that can support both native T1 TDM services and Ethernet services. But, the major changes are the higher capacities required by LTE cell sites. A detail comparison of wireless capacity requirements for 2G, 3G, and LTE networks are shown in Table 1.

### 3. 5G backhaul requirements and challenges

Enhance the network reliability and reduce the cost efficiency always been a major challenge for the cellular network operator and there is no magic solution to that demand [19]. With the evolution of mobile network, the capacity requirement of the transport network from the core raises significantly [23]. The major backhaul challenges that mobile network operator had to deal with up to 4G network includes capacity, availability, deployment cost, and long distance reach [16]. But, 5G network will interconnect billions of new start devices with the numerous use cases and services, which will support machine-to-machine (M2M) services and Internet of Things (IoT) to the mobile network [6, 8]. These new smart devices will not only enhance the backhaul capacity requirement, but it will also add two additional challenges in the backhaul network: (a) ultralow latency of 1 ms (round trip) connectivity requirements, and (b) denser small cell deployment. This section describes the 5G backhaul requirements and potential challenges.

#### 3.1. Capacity

The evolution of 5G cellular network is positioned to address new services and demands for business contexts of 2020 and beyond [29]. It is expected that 5G network will enable a fully mobile and connected society that empower socio-economic transformation in many ways and even some of which are unimagined today. To fulfill the demand of fully mobile and connected society can be characterized by the tremendous increase in the number of connectivity and traffic volume density [29]. According to Nokia, the number of connecting devices per mobile users will be ten to one hundred that includes, mobile phone, laptop, tablet, smart watch to smart shirts [11]. In addition, the number of connected machines and sensor devices in the industry and public infrastructure will increase. According to Ceragon, the forecasted capacity increase could be 1000 compared to the capacity density in current 4G/4.5G networks [30, 31]. So, it is obvious that the evolution of 5G networks from LTE/LTE-A will need higher capacity backhaul links per cell site: while LTE/LTE-A networks need hundreds of Mbps, 5G network will need to support tens of Gbps, shown in Figure 1.

### 3.2. Availability

each eNodeB radio. So, the resultant network is indeed much simpler and flatter, with far fewer

Voice spectral efficiency (bits/Hz)

GSM 2G 1.2 0.52 3 1.3 1

HSDPA 3G 5 0 2 3 21.0 14 LTE 4G 5 0 3.8 3 39.9 n/a LTE 4G 10 0 3.8 3 79.8 n/a

1.2 2.3 0.52 1 3 6.1 4

Data efficiency (bits/Hz)


*3.4. Alternative Income and Safety Nets for Farmers*

Information on alternative sources of income and safety nets the farmers depended on during the 2020 minor season maize yield loss was solicited. Table 3 shows that the farmers relied on diverse economic activities to cushion the financial burden that arose from maize production losses. In Ejura, most of the farmers (79%) relied on the sale of animals such as goat, sheep, chicken, and cattle to earn money for household needs, while in Kasei and Anyinasu, the farmers (78 and 75%, respectively) notably engaged in non-farm activities, such as trading and the running of commercial transport. Further, in Kasei and Anyinasu, a cross section of the farmers reported that they depended on income from the sale of other crops, such as cassava and vegetables. However, there were a few of the farmers in the study communities (22% Anyinasu, 17% in Kasei and 16% in Ejura) who reported that they did nothing during the maize production failure.

In terms of social safety nets, the results show that most respondents (average of ~60%) indicated that they had none. For those who depended on safety nets, the prominent ones were support and remittances from family members and friends living in or outside the communities. Others depended on maize grains stored and income saved from the previous years. Dapilah, et al. [18] reported that diverse activities and social networks foster climate change adaptation in northern Ghana through the diversification of livelihood activities. In the present study, it was also found that family support and remittances played a valuable role in minimizing the adverse impacts of maize production failure on farmers and their households. The study also revealed that the initiatives of individual farmers and farm management practices, particularly livestock rearing, the storage of maize grains, and income from the previous years' harvest, equally played a crucial role in reducing the negative impacts of the 2020 minor season crop failure on the farmers' livelihoods.

**Figure 4.** Frequency of dry spells for the (**a**) major and (**b**) minor cropping seasons for the period 2015–2020, and longest dry spell in days for (**c**) major and (**d**) minor cropping seasons for the period 2015–2020. A dry spell is defined as a sequence of four consecutive days or more during which precipitation is less than 1 mm. *3.4. Alternative Income and Safety Nets for Farmers*  **Figure 4.** Frequency of dry spells for the (**a**) major and (**b**) minor cropping seasons for the period 2015–2020, and longest dry spell in days for (**c**) major and (**d**) minor cropping seasons for the period 2015–2020. A dry spell is defined as a sequence of four consecutive days or more during which precipitation is less than 1 mm.

### Information on alternative sources of income and safety nets the farmers depended *3.5. Changes in Agronomic Practices in Response to the 2020 Maize Production Failure*

on during the 2020 minor season maize yield loss was solicited. Table 3 shows that the farmers relied on diverse economic activities to cushion the financial burden that arose from maize production losses. In Ejura, most of the farmers (79%) relied on the sale of animals such as goat, sheep, chicken, and cattle to earn money for household needs, while in Kasei and Anyinasu, the farmers (78 and 75%, respectively) notably engaged in nonfarm activities, such as trading and the running of commercial transport. Further, in Kasei and Anyinasu, a cross section of the farmers reported that they depended on income from the sale of other crops, such as cassava and vegetables. However, there were a few of the farmers in the study communities (22% Anyinasu, 17% in Kasei and 16% in Ejura) who reported that they did nothing during the maize production failure. The study sought information on how the experiences and lessons from the 2020 minor season maize production failure have shaped the farmers' agronomic practices. Table 4 showed that the experience from the 2020 minor season crop failure has indeed brought about some agronomic changes in maize cultivation. According to the farmers and the key informants, agronomic changes have become necessary to avert running into the same challenges experienced in 2020. Due to the difficulty for the farmers to master the onset and cessation of the minor season rain, of late, some of the farmers preferred doing early sowing of maize to take advantage of potential early rains. On the contrary, a cross section of the farmers preferred late sowing to make sure the rains are stable before planting (Table 4). However, both options are not without drawbacks because according to the Municipal Agriculture Extension Officer, in recent years, the minor season rains seemed to delay and last for a very short time when it comes. Either way it affects early and late sowing:

The minor season rain is increasingly becoming very difficult for farmers to predict its onset and cessation. This implies that opting for only early or late sowing increases the risk of maize failure. A viable way to go is we (Extension Officers) advise farmers to do split sowing of maize so that they do not put their eggs in one basket . . . to avoid total crop failure in case the rains did not come as expected (Key informant at Ejura).

As mentioned previously, besides climate change, fall armyworms were reported to have significantly contributed to the maize production failures. In response, the farmers (53%, 44% and 58% in Ejura, Kasei and Anyinasu, respectively) reported that they have increased the use of pesticides in a bid to control the pests. The interviews revealed that the farmers have been experimenting (trial and error) with different pesticides to control the pest. The farmers reported having used at least five different insecticides, such as Lambda Super 2.5, Diband and Samprifos, ashes, Lindane, etc., in the last year in an attempt to control the fall armyworm, yet no significant impacts have been observed. Adzawla and Alhassan [19] pointed out that farmers' adaptation to climate change is important at the local level, as it helps to enhance sustainable food production. The authors reported that maize farmers in Northern Ghana are adapting to climate change by practicing row planting, mixed cropping, intercropping, and changing planting dates. The results from the present study show that the farmers are using local knowledge and farming experience to adapt to climate change, particularly unpredictable rainfall during the minor season, and to control the fall armyworm. Furthermore, the farmers in Ejura-Sekyedumase Municipality are also tackling poor nutrient status and soil degradation by using fertilizers and practicing maize rotation with leguminous crops for soil nutrient replenishment, and this way improving soil quality for crop production.

**Table 3.** Alternative economic activities and safety nets of respondents (multiple responses).


**7.1 Top-down method**

In this method, larger compounds are broken down into nano-scaled materials by using mechanical and chemical forces. Mechanical milling, lithography, electrospinning, etching, sputtering, and laser ablation are the most common topdown approaches to nanoparticle synthesis.