FieldFox Microwave Analyzers – 5G gNB Field Test Solutions

5G gNB Field Test Solution

5G NR Technology Trends

5G technologies provide dramatic network speed improvement and superfast connection time. 5G New Radio (NR) is the 3rd Generation Partnership Project (3GPP) standard for the wireless network running on the sub-7.125 GHz frequency band (FR1) and above 24.250 GHz on the millimeter-wave (mmWave) frequency band (FR2). 5G offers gigabit per second data rates. 

5G networks use wider bandwidths, higher operating frequencies, and active antenna systems, such as phased array antennas. The key challenges for 5G network deployment are characterizing air interface path loss, optimizing beam coverage, and mitigating interference issues.

Keysight’s 5G gNodeB (gNB) field test solution, based on the FieldFox microwave analyzer, provides a complete toolkit for radio frequency (RF) engineers and technicians to install and troubleshoot 5G networks. This solution can verify hardware gNB performance, such as cable and antenna conditions, transmit power, control channel power, and RF spurious responses. It can also verify signal quality over the air, including multipath synchronization signal information and coverage area path loss, as well as identify and troubleshoot interference issues.

5G coverage testing with FieldFox

5G networks use beamforming and massive multiple-input/multiple-output (MIMO) to achieve high data rates. Beam steering of the synchronization signal blocks (SSBs) allows the base station antenna to steer beams in specific directions and target different users (Figure 1). Unlike Long Term Evolution (LTE) network synchronization signals, 5G SSBs are not always “on”, making it challenging to determine the location of the 5G signal.

Detect 5G synchronization signals and interference with RTSA

Real-time spectrum analysis (RTSA) mode on the FieldFox analyzer can quickly and reliably detect 5G signals and the location of the SSBs (Figures 2 through 5). In LTE networks, the synchronization signals are always located at the carrier center frequency. In 5G networks, the SSBs can be offset from the carrier center frequency. In addition, RTSA can provide insight into beamforming performance and identify interference issues. FieldFox supports up to 100 MHz of real-time bandwidth with gap-free data capture that can detect pulses as narrow as 5.52 µs with a 100% probability of intercept (POI). When paired with a phased array antenna, FieldFox in RTSA mode facilitates cell search and displays beam-sweeping SSBs. This view includes the primary, secondary, and extended synchronization signals in the control channel. From this display, you can see any interfering or transient signals and measure beam performance.

The rollout of 5G and an ever-increasing number of wireless technologies introduce many opportunities for interference. 5G base stations, for instance, can create interfering signals for nearby satellite ground stations. Some of those satellite ground stations may be responsible for emergency radio communications. Interfering with such critical communications could cause a disaster. That is why identifying interfering signals in the field when developing and deploying 5G networks is crucial. 

Additionally, adjacent cells can cause interference. If the data channels are interfering, the speeds at which these signals travel are too fast for the interference to impact network performance. However, interference in the SSBs can bring down the whole cell site. Proper SSB transmissions are essential for field deployment. Having in your field kit a solution that can capture interference signals and visualize SSBs facilitates your 5G transformation.