Boingo, Microsoft, Broadcom blast Ericsson’s LTE-U claims

Ericsson LTE-U
Ericsson's Sept. 2 filing with the FCC includes charts like this one designed to show how LTE-U is continuously adapting to Wi-Fi channel usage. Image: Ericsson

Boingo Wireless, Microsoft, Broadcom and Ruckus Wireless are among those calling out Ericsson for a Sept. 2 report in which Ericsson shared results of its LTE-U/Wi-Fi coexistence tests. Not surprisingly, the tests found that LTE-U will fairly coexist with Wi-Fi.

The companies challenged Ericsson’s claim that its tests are closely aligned with the Wi-Fi Alliance (WFA) test plan. “While one can certainly detect echoes of ideas from WFA in the Ericsson submission, there is little that is recognizable and much that is completely novel,” they wrote. “There are several test cases included that do not appear anywhere in the WFA test plan, and cannot serve as substitutes for the important procedures that Ericsson omitted.”

The WFA is currently on target to release its coexistence test plan on Sept. 21. Once that is released, companies will be able to conduct tests in a third-party laboratory to see if products pass muster.

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In its Sept. 2 filing with the FCC, Ericsson said it was filing the results in the hope that the commission will find the data valuable. Engineers tested channel selection, reselection and co-channel operation to demonstrate that LTE-U will fairly coexist with Wi-Fi. The tests were performed in a variety of different radio conditions, both in labs and in live networks. They were designed to align as closely as possible with the Wi-Fi Alliance LTE-U coexistence test plan, Ericsson said.

The band of seven companies that are calling out Ericsson said the company omitted material data and test results required to be disclosed by the WFA test plan, which makes it impossible to evaluate Ericsson’s coexistence claims.

Furthermore, based on what Ericsson did publish, “it is clear that this proprietary internal test changed or failed to include several of the most important features of the WFA test plan, rendering its testing unreliable as a decision-making tool for the FCC,” they wrote. “The Ericsson test is therefore very different from the tests prescribed by the WFA test plan.”

They note that Ericsson’s test does not use the Wi-Fi signal levels mandated by the WFA test plan. The signal levels were one of the biggest points of contention among the stakeholders hammering out the test plan, which requires testing in the presence of a Wi-Fi signal with different signal receive strengths, including -82 dBm.

Hewlett-Packard Enterprise, Cypress Semiconductor and the National Cable & Telecommunications Association (NCTA) also signed the letter to the FCC asking the commission not to put too much stock into Ericsson’s report.

An Ericsson spokeswoman told FierceWirelessTech on Wednesday that the company did not have any further comment at this time.  

Ericsson’s 27-page filing on Sept. 2 presented results from three different lab and live network LTE-U test activities showing LTE-U channel selection, reselection and the adaptation of the CSAT duty cycle during operation under different channel conditions and traffic patterns. “The tests followed the intent of the WFA LTE-U Coexistence Test Plan with modifications to make the tests practical and executable in the different test environments,” Ericsson explained in its presentation.

For more:
- see this filing (PDF)
- see this Ericsson filing (PDF)

Related articles:
Wi-Fi Alliance assures coexistence test plan on track for Sept. 21 delivery
Wi-Fi Alliance: August target for coexistence test plan with LTE-U could slip into September
Broadcom: LTE-U as currently contemplated would be a 'disaster' for Wi-Fi

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