Microsoft, HPE and Broadcom have all voiced their support for the Wi-Fi Alliance’s proposed LTE-U coexistence test plan.
The companies, all founding members of the WFA, praised the “integrity and speed” of the plan, which is on track to be finalized in September. They urged the WFA to ignore detractors like Verizon and Qualcomm that have claimed the test plan has serious faults.
“In making the final decisions about the test plan design, Microsoft, HPE and Broadcom encourage WFA to resist continued attempts to change the test plan in a manner which would undermine the longstanding agreement between the cellular and Wi-Fi industries that an unlicensed LTE base station should cause no more impact to existing Wi-Fi networks than adding another Wi-Fi network,” the companies wrote in a letter.
Still, in spite the companies’ support for WFA’s plan, they still expressed some reservations, in particular with what they determined were “significantly stronger signal levels than operating capabilities of most Wi-Fi clients.
“Many consumer electronic devices, such as set top boxes, game consoles and DVD players, are typically installed behind TVs or cabinets, where the Wi-Fi signal is much weaker than what is typically received at the center of the room,” the companies wrote. “In many instances these devices are adjacent to exterior walls, and would be greatly impacted by LTE-U transmissions in adjacent buildings, apartments, or even outdoors. In other words, under the current test plan hundreds of millions of Wi-Fi devices operating today would be ignored by LTE-U equipment while it is calculating how to share fairly.”
The companies also warned that LTE-U proponents pushing to exclude lower signal level testing could undermine the validity of the testing process and could indicate that “LTE-U Forum members are having difficulty fulfilling their promise of fairness in a number of real-world scenarios using the methods they have chosen, and now seek to only protect high-end Wi-Fi devices used in enterprise deployments.”
Microsoft, HPE and Broadcom leveling accusations at the LTE-U Forum comes amid Forum members like Qualcomm and Verizon taking their own shots at the WFA’s plan. Both Qualcomm and Verizon have pushed back at the WFA’s claims that the test plan is a compromise, with Verizon calling it “fundamentally unfair and biased.”
“First, the plan includes an in-device coexistence test that has nothing to do with spectrum sharing. Second, it proposes an unrealistic and inaccurate Wi-Fi interference baseline not based on a single vendor rather than on multiple vendors. Finally, it proposes a -82 dBm energy detection threshold based on uncalibrated RSSI measurements, which is not based on sound engineering practices,” said Verizon in an FCC filing.
While Qualcomm has expressed similar concerns with WFA’s plan, the company has also recently called out Wi-Fi for not being the best spectrum sharer either. According to findings from recent tests Qualcomm performed, Wi-Fi access points, even models from the same manufacturers, can tilt the preferred 50/50 sharing scenario closer to 90/10 in some instances.
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