Cable, Telecom and LTE-U: Peace in Our Time – Maybe

By Carl Weinschenk

Cellular operators and WiFi providers, led by cable operators, are at a crossroads on the process by which LTE will be used on unlicensed spectrum. The two sides seemed to finally be headed toward a solution—until what apparently was a stormy workshop on June 22. WiFi uses spectrum that is unlicensed. It is, therefore, free—and crowded. Cellular operators, conversely, lease spectrum from the government. It has a price tag—but totally under their control. It’s the telecom difference between riding a bus or taking a cab. The two worlds didn’t overlap until the cellular operators, pushed by the massive growth of demand and attracted by the fact that the 5 GHz spectrum is free, decided that they wanted into the party for their LTE services.

There is no problem with them doing this. It is as open to them as it is to any other industry segment. There is, however, a practical issue. LTE was developed under the premise that it wouldn’t have to share spectrum. Therefore, it has no mechanisms to do such things as relinquish control when it is time for another station to take over. The nub of the problem: Could Qualcomm’s North American focused approach—LTE-U—be a good enough neighbor to operate on unlicensed spectrum without degrading the service of other users? The incumbent users of unlicensed spectrum, led by the cable industry, didn’t think so; the cellular companies were adamant that they could. Indeed, they maintained that their stations were even better neighbors than WiFi-based access points and stations.

Last year brought a great deal of acrimony between the two sides, but things took an upward term in late fall. The bottom line is that both sides recognized that cooperation was the only practical option. “The single defining moment that led to the change in tone… was the point where both sides made it very clear that they are committed to the idea that users will continue to experience WiFi as they do today,” said Kevin Robinson, vp, marketing for the Wi-Fi Alliance, which is overseeing establishment and management of the co-existence framework. The industries seemed as of early June to be in the home stretch. Rob Alderfer, CableLabs’ technology policy vp, said that the test plan was in the process of being validated. The test procedure will indicate how well LTE devices on WiFi networks respond to the needs of other users of a network. But a June 22 coexistence workshop in San Jose didn’t go so well, with Qualcomm complaining afterwards that it’s disappointed in continued delays in finalizing a LTEU/Wi-Fi test plan with the Wi-Fi Alliance. It also criticized the substance presented by the WFA staff at the WFA workshop, which it said “lacked technical merit and was a sharp departure from Wi-Fi Alliance staff past presentations and views and from the view of any other standards body or regulator around the world.”

In its statement, Qualcomm argued to end the validation process and deem the original test plan final. For its part, WFA said it’s committed to coexistence as quickly as possible and is confident it will deliver a solution in a timely manner. “Delivering coexistence for two different industries is no easy feat. Technical challenges exist and work is time consuming,” WFA told us. “While a significant number of test cases are nearly validated, validation of all test cases is necessary to deliver a test plan that will determine whether LTE-U devices are able to fairly share unlicensed spectrum with Wi-Fi. Wi-Fi Alliance is exploring every possible option to accelerate the work while still ensuring the test objectives are met.” – Carl Weinschenk