Report: T-Mobile to use 4×2 MIMO to boost LTE network performance

T-Mobile US (NYSE:TMUS) plans to add more antennas to its Radio Access Network to boost the performance of its small but growing LTE network, according to a report from GigaOM.

The report, citing information from T-Mobile's two main LTE network infrastructure vendors, Ericsson (NASDAQ:ERIC) and Nokia Siemens Networks, said that T-Mobile will use 4x2 MIMO antenna technology in its network. The report noted that this will double the number of antennas--and thus, data transmission paths--used in standard LTE deployments, which use 2x2 MIMO. MIMO sends data over two parallel transmission paths from cell towers to devices at the edge of the network.

The net effect of using 4x2 MIMO will be that customers at the cell edge will have a better chance at getting a strong LTE signal since there will be more signals sent to their devices.

A T-Mobile spokesman said "4x2 MIMO is one of the multiple LTE technologies T-Mobile is considering for future use. We understand the performance and value of the technology, but we have not committed to deployment."

Mark McDiarmid, T-Mobiles' vice president of radio network engineering, confirmed that 4x2 MIMO is one of the multiple LTE and LTE Advanced technologies T-Mobile is contemplating.

"We have a very good handle on what 4x2 MIMO can do for us," he said. "And we're one of the few that are in a position to use it."

Nokia Siemens indicated to GigaOM that it will roll out the technology with "a major U.S. operator" in the next 12 months; T-Mobile is NSN's only major U.S. customer. The switch will require software upgrades at T-Mobile base stations as well as the deployment of extra antennas, but should not be too expensive. Petri Hautakangas, NSN's North American head of technology, told GigaOM  that in lab tests of 4x2 MIMO, the companies are seeing speed gains at the cell edge as high as 100 percent on the uplink and between a 50 percent to 60 percent increase in downlink speeds.

T-Mobile's LTE network is still relatively small compared to the LTE networks of Verizon Wireless (NYSE:VZ) and AT&T Mobility (NYSE:T). Verizon's LTE network covers 287 million POPs and Verizon will begin adding AWS spectrum to boost capacity in urban markets later this year. AT&T's LTE network covers more than 200 million POPs and the carrier plans to cover 270 million by year-end. 

T-Mobile has expressed confidence that it will surpass 100 million POPs covered by LTE by the end of this month and 200 million by year-end. Sprint Nextel (NYSE:S) also plans on having 200 million POPs covered with LTE by the end of 2013.

Although T-Mobile has claimed that it is farther ahead of its rivals in deploying LTE Advanced technology, in reality most carriers are moving at the same pace. AT&T has said it expects to launch LTE Advanced sometime this year. Verizon is also actively considering it and Sprint has said some LTE Advanced features are already in place in its network.

For more:
- see this GigaOM article

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Article updated June 5 with a statement from T-Mobile.