mmWave Mythology, Part II
By Kent Lundgren, VP Marketing
This blog entry presents two more millimeter myths presented by Pivotal's VP of Engineering, Alex Katko, at Avalon’s Technology Users Forum in Dallas on January 9, 2024. You can read about the first two myths in mmWave Mythology, Part I.
Recall that Alex’s presentation, “mmWave Mythology: Myths Busted or Confirmed Through Real Deployments,” challenged his audience to determine which of nine mmWave myths were confirmed, busted or plausible, based on Pivotal Turnkey Service’s experience designing and deploying Pivot 5G repeater networks. These networks serve fixed wireless access (FWA) to hundreds of multiple dwelling unit (MDU) buildings across the United States. Pivot 5G network repeaters typically attach to utility poles or streetlights and re-direct mmWave signals from base stations to indoor subscriber equipment behind glass windows and doors, even exterior walls.
mmWave Mythology, Part II presents these myths:
- Foliage Will Block mmWave Signals.
- Test Equipment Alone is Sufficient to Qualify Service.
Myth #3: Foliage Will Block mmWave
The prevailing wisdom is that foliage will kill line-of-sight, that a tree in the site path of an acceptable survey in Winter will destroy service in the Spring. In Part I we learned that low-e glass is manageable. Is it the same for foliage?
Plausible
Foliage will weaken mmWave but can be prevented from killing it. The first countermeasure to avoid detuning and oscillation is easy: leave some clearance between the antenna and the foliage. Figure 1 shows a need for clearance.
Once the nearfield is cleared, just punch through it with more power. It doesn’t take much. Figure 2 shows that an extra 5-8 dB of gain can make difference between no signal, on the left, and adequate signal, on the right.
Myth #9: Test Equipment Alone is Sufficient to Qualify Service
Test equipment vendors have introduced major innovations over the years, allowing over-the-air tests that would have been impossible in the 4G era. No wonder that many site surveyors say that with the right gear, any kind of service can be tested and/or qualified. This claim is almost confirmed.
Busted
Test equipment will accurately characterize link properties such as SINR and RSRP, but the only way to qualify FWA service, i.e., end-to-end provisioning, is to use a CPE with the high power, high gain, beamforming QTM5x7 chipset module — not the QTM5x5 found in phones.
While test equipment can show healthy SINR, RSRP and some KPIs, CPEs can reveal unhealthy network configurations, such as a missing LTE anchor in a non-standalone 5G network. In this case, there would be no connection, no service. CPE can characterize underperformance in the uplink too. Test equipment is not well-suited for this purpose.
Sometimes, despite healthy quantitative parameters, the downlink might show substandard throughput, such as 1 Gbps. This might be caused by speed caps, such as 1 Gbps, on:
- Backhaul, particularly in indoor venues.
- Network interface card (NIC) on a test laptop connected to the CPE.
- CPE, due to carrier FWA service plan policy.
Finally, accurate speed testing ought to be “tailored” to the carrier’s network to avoid bottlenecks in the broader Internet. A tailored speed test could also include setting up an iPerf server at the edge of the carrier’s network, e.g., AWS Wavelength.
Stay tuned for more mmWave myths, tips and tricks in blogs to follow.