Paving the way for the next wireless technology breakthrough

The pace of wireless innovation is getting faster and faster, enabling faster, more responsive, and more reliable connectivity around the world. The wireless communications industry is primed for major technological change in multiple systems. To increase data throughput, cellular communications are upgrading from 4G to 5G, while satellite communications providers are building networks in space, aiming to provide high-speed communications to every corner of the globe.

By Eric Hsu, Product Marketing Manager, Keysight Technologies

Paving the way for the next wireless technology breakthrough

The pace of wireless innovation is getting faster and faster, enabling faster, more responsive, and more reliable connectivity around the world. The wireless communications industry is primed for major technological change in multiple systems. To increase data throughput, cellular communications are upgrading from 4G to 5G, while satellite communications providers are building networks in space, aiming to provide high-speed communications to every corner of the globe. Wireless engineers want breakthroughs in technology that maximize system throughput and create robust links and data processing capabilities. For the wireless system physical layer, key technologies involve larger bandwidths, higher-order modulation schemes, and multi-antenna technology in wireless systems.

Greater signal bandwidth

Due to the limited spectrum available for allocation, standards development organizations want to provide greater bandwidth in higher frequency bands. For example, the frequency range 2 (FR2) specified in 5G New Radio (NR) Rel-15 is 24.25 GHz to 52.6 GHz with a maximum channel bandwidth of 400 MHz. Rel-16 introduces license-exempt frequency bands in the 5 GHz and 6 GHz frequency ranges. By mid-2022, 3GPP Rel-17 will extend the unlicensed spectrum to 71 GHz.

Satellite communications provide connectivity for television, telephony, broadband Internet services and military communications. Satellites can operate in many frequency bands between L-band and Ka-band. The International Telecommunication Union (ITU) has allocated 71 to 76 GHz and 81 to 86 GHz in the W-band to the satellite service. Commercial satellite operators want more bandwidth in these bands. On June 30, 2021, a satellite equipped with a W-band wireless transmitter was successfully launched into the sky. In the near future, we can expect to witness more commercial projects in the W-band.

The mmWave band provides more usable bandwidth. Large bandwidth enables high throughput data and low latency, but the increased bandwidth also introduces more noise, which affects system performance. Wireless engineers need to manage the noise issues of broadband communications. In addition to generating more system noise, expanding bandwidth at higher frequency bands creates other challenges for design and test, such as path loss, frequency response, and phase noise.

Higher order modulation schemes

Higher-order modulation schemes can increase the data rate without increasing the signal bandwidth, while the symbols are spaced closer together, making them more sensitive to noise. As modulation density increases, devices require better modulation quality. Table 1 lists the error vector magnitude (EVM) requirements specified in 3GPP Rel-16 technical specification 38.141 for 5G NR base stations. 3GPP is also considering 1,024 QAM with tighter design and test margins.

modulation scheme

False EVM requested (%)

QPSK

18.5%

16QAM

13.5%

64QAM

9%

256QAM

4.5%

Table 1. Modulation quality requirements in 5G NR base station transmitter testing.

Greater signal bandwidth and higher-order modulation schemes both increase throughput. However, greater bandwidth does not necessarily mean higher system capacity. You have to consider the signal-to-noise ratio (SNR) of the communication system. Proper SNR is critical to maintaining communication links. The larger the bandwidth, the more noise is introduced into the system; the higher the modulation scheme, the more susceptible it is to noise. You need to transmit high-power signals without distortion and reduce system noise in order to maintain the performance of the communication link. To test your design, you need to accurately characterize every component and every subsystem shown in Figure 1.


Figure 1. Accurately verify RF components with stimulus-response measurements.

Multiple Antenna Technology

Most wireless systems used in commercial applications and aerospace and defense use multiple antennas at the receiver and/or transmitter to improve overall system performance. These techniques include spatial diversity, spatial multiplexing, and beamforming. Engineers employ multi-antenna techniques to achieve diversity, multiplexing, or antenna gain. Such techniques help to improve the data throughput and SNR of wireless system receivers. For example, 5G NR uses 8 spatial streams in FR1 to improve spectral efficiency without increasing signal bandwidth. 3GPP has therefore defined in Technical Specification (TS) 38.141-1 how to use multiple spatial streams for performance testing for 5G NR base stations. Testing requires up to two transmitter antennas and eight receiver antennas, with specific propagation conditions, correlation matrices, and SNR applied to each test case. Figure 2 shows a 5G base station performance multiple-input multiple-output (MIMO) test configuration for two transmitter antennas and four receiver antennas, which can provide hybrid automatic repeat request (HARQ) feedback.


Figure 2. Test setup for testing 5G NR base station performance using a four-channel signal generator.

Compared to IEEE 802.11ax, the next-generation Wi-Fi standard, IEEE 802.11be (Wi-Fi 7), offers twice the signal bandwidth, 16 spatial streams, and four times the density of modulation schemes. Together, they provide data rates up to 40 Gbps. Table 2 lists the major changes to the IEEE 802.11 physical layer.

IEEE 802.11 standard

Maximum signal bandwidth

modulation scheme

Number of spatial streams

802.11be (Wi-Fi 7)

320MHz

OFDM, up to 4,096 QAM

up to 16

802.11ax (Wi-Fi 6)

160MHz

OFDM, up to 1,024 QAM

up to 8

Table 2. IEEE 802.11 standards.

To test multi-antenna systems using spatial diversity, spatial multiplexing, and multiple antenna array techniques, you need a test system that can provide multi-channel signals with stable phase relationships between the signals. However, commercial signal generators use a separate synthesizer to upconvert intermediate frequency (IF) signals to RF signals. The test system must provide precise timing synchronization between channels to simulate multi-channel test signals. The phase between the test signals must be coherent and controllable. Figure 3 shows a fully integrated, calibrated and synchronized signal generation and analysis solution that can help you minimize measurement uncertainty for multi-antenna testing.


Figure 3. Multi-channel test solution using the Keysight M9484C VXG four-channel vector signal generator and four-port oscilloscope.

Summarize

Next-generation wireless communication systems such as 5G, satellite, and Wi-Fi require higher frequencies, larger bandwidths, more complex modulation schemes, and multi-antenna designs. This will help you address new design and test challenges, such as increased test complexity, measurement uncertainty, excessive path loss and noise, which can affect device performance.

To meet these challenges, you need a scalable test solution that accurately and easily supports larger frequency coverage, wider bandwidth, and multi-channel applications. With a fully integrated, calibrated and synchronized solution, you can reduce test complexity and get repeatable and accurate results quickly.

About Keysight

Keysight Technologies provides advanced design and verification solutions designed to accelerate innovation and create a secure, connected world. While focusing on speed and precision, we are also working on enabling deeper insights and analysis through software. Throughout the product development cycle, from design simulation, prototyping, automated software testing, manufacturing analysis, to network performance optimization and visualization, Keysight can bring forward-looking technologies and products to market faster. Market to fully meet the needs of enterprises, service providers and cloud environments. Our customers span the global communications and industrial ecosystem, aerospace and defense, automotive, energy, semiconductor and general electronics markets. In fiscal 2021, Keysight’s revenue was $4.9 billion. For more information about Keysight Technologies, Inc. (NYSE: KEYS), visit www.keysight.com.

The pace of wireless innovation is getting faster and faster, enabling faster, more responsive, and more reliable connectivity around the world. The wireless communications industry is primed for major technological change in multiple systems. To increase data throughput, cellular communications are upgrading from 4G to 5G, while satellite communications providers are building networks in space, aiming to provide high-speed communications to every corner of the globe.

By Eric Hsu, Product Marketing Manager, Keysight Technologies

The pace of wireless innovation is getting faster and faster, enabling faster, more responsive, and more reliable connectivity around the world. The wireless communications industry is primed for major technological change in multiple systems. To increase data throughput, cellular communications are upgrading from 4G to 5G, while satellite communications providers are building networks in space, aiming to provide high-speed communications to every corner of the globe. Wireless engineers want breakthroughs in technology that maximize system throughput and create robust links and data processing capabilities. For the wireless system physical layer, key technologies involve larger bandwidths, higher-order modulation schemes, and multi-antenna technology in wireless systems.

Greater signal bandwidth

Due to the limited spectrum available for allocation, standards development organizations want to provide greater bandwidth in higher frequency bands. For example, the frequency range 2 (FR2) specified in 5G New Radio (NR) Rel-15 is 24.25 GHz to 52.6 GHz with a maximum channel bandwidth of 400 MHz. Rel-16 introduces license-exempt frequency bands in the 5 GHz and 6 GHz frequency ranges. By mid-2022, 3GPP Rel-17 will extend the unlicensed spectrum to 71 GHz.

Satellite communications provide connectivity for television, telephony, broadband Internet services and military communications. Satellites can operate in many frequency bands between L-band and Ka-band. The International Telecommunication Union (ITU) has allocated 71 to 76 GHz and 81 to 86 GHz in the W-band to the satellite service. Commercial satellite operators want more bandwidth in these bands. On June 30, 2021, a satellite equipped with a W-band wireless transmitter was successfully launched into the sky. In the near future, we can expect to witness more commercial projects in the W-band.

The mmWave band provides more usable bandwidth. Large bandwidth enables high throughput data and low latency, but the increased bandwidth also introduces more noise, which affects system performance. Wireless engineers need to manage the noise issues of broadband communications. In addition to generating more system noise, expanding bandwidth at higher frequency bands creates other challenges for design and test, such as path loss, frequency response, and phase noise.

Higher order modulation schemes

Higher-order modulation schemes can increase the data rate without increasing the signal bandwidth, while the symbols are spaced closer together, making them more sensitive to noise. As modulation density increases, devices require better modulation quality. Table 1 lists the error vector magnitude (EVM) requirements specified in 3GPP Rel-16 technical specification 38.141 for 5G NR base stations. 3GPP is also considering 1,024 QAM with tighter design and test margins.

modulation scheme

False EVM requested (%)

QPSK

18.5%

16QAM

13.5%

64QAM

9%

256QAM

4.5%

Table 1. Modulation quality requirements in 5G NR base station transmitter testing.

Greater signal bandwidth and higher-order modulation schemes both increase throughput. However, greater bandwidth does not necessarily mean higher system capacity. You have to consider the signal-to-noise ratio (SNR) of the communication system. Proper SNR is critical to maintaining communication links. The larger the bandwidth, the more noise is introduced into the system; the higher the modulation scheme, the more susceptible it is to noise. You need to transmit high-power signals without distortion and reduce system noise in order to maintain the performance of the communication link. To test your design, you need to accurately characterize every component and every subsystem shown in Figure 1.


Figure 1. Accurately verify RF components with stimulus-response measurements.

Multiple Antenna Technology

Most wireless systems used in commercial applications and aerospace and defense use multiple antennas at the receiver and/or transmitter to improve overall system performance. These techniques include spatial diversity, spatial multiplexing, and beamforming. Engineers employ multi-antenna techniques to achieve diversity, multiplexing, or antenna gain. Such techniques help to improve the data throughput and SNR of wireless system receivers. For example, 5G NR uses 8 spatial streams in FR1 to improve spectral efficiency without increasing signal bandwidth. 3GPP has therefore defined in Technical Specification (TS) 38.141-1 how to use multiple spatial streams for performance testing for 5G NR base stations. Testing requires up to two transmitter antennas and eight receiver antennas, with specific propagation conditions, correlation matrices, and SNR applied to each test case. Figure 2 shows a 5G base station performance multiple-input multiple-output (MIMO) test configuration for two transmitter antennas and four receiver antennas, which can provide hybrid automatic repeat request (HARQ) feedback.


Figure 2. Test setup for testing 5G NR base station performance using a four-channel signal generator.

Compared to IEEE 802.11ax, the next-generation Wi-Fi standard, IEEE 802.11be (Wi-Fi 7), offers twice the signal bandwidth, 16 spatial streams, and four times the density of modulation schemes. Together, they provide data rates up to 40 Gbps. Table 2 lists the major changes to the IEEE 802.11 physical layer.

IEEE 802.11 standard

Maximum signal bandwidth

modulation scheme

Number of spatial streams

802.11be (Wi-Fi 7)

320MHz

OFDM, up to 4,096 QAM

up to 16

802.11ax (Wi-Fi 6)

160MHz

OFDM, up to 1,024 QAM

up to 8

Table 2. IEEE 802.11 standards.

To test multi-antenna systems using spatial diversity, spatial multiplexing, and multiple antenna array techniques, you need a test system that can provide multi-channel signals with stable phase relationships between the signals. However, commercial signal generators use a separate synthesizer to upconvert intermediate frequency (IF) signals to RF signals. The test system must provide precise timing synchronization between channels to simulate multi-channel test signals. The phase between the test signals must be coherent and controllable. Figure 3 shows a fully integrated, calibrated and synchronized signal generation and analysis solution that can help you minimize measurement uncertainty for multi-antenna testing.


Figure 3. Multi-channel test solution using the Keysight M9484C VXG four-channel vector signal generator and four-port oscilloscope.

Summarize

Next-generation wireless communication systems such as 5G, satellite, and Wi-Fi require higher frequencies, larger bandwidths, more complex modulation schemes, and multi-antenna designs. This will help you address new design and test challenges, such as increased test complexity, measurement uncertainty, excessive path loss and noise, which can affect device performance.

To meet these challenges, you need a scalable test solution that accurately and easily supports larger frequency coverage, wider bandwidth, and multi-channel applications. With a fully integrated, calibrated and synchronized solution, you can reduce test complexity and get repeatable and accurate results quickly.

About Keysight

Keysight Technologies provides advanced design and verification solutions designed to accelerate innovation and create a secure, connected world. While focusing on speed and precision, we are also working on enabling deeper insights and analysis through software. Throughout the product development cycle, from design simulation, prototyping, automated software testing, manufacturing analysis, to network performance optimization and visualization, Keysight can bring forward-looking technologies and products to market faster. Market to fully meet the needs of enterprises, service providers and cloud environments. Our customers span the global communications and industrial ecosystem, aerospace and defense, automotive, energy, semiconductor and general electronics markets. In fiscal 2021, Keysight’s revenue was $4.9 billion. For more information about Keysight Technologies, Inc. (NYSE: KEYS), visit www.keysight.com.

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