Verizon begins deploying carrier aggregation in 20x20 MHz channels, 4x4 MIMO for faster LTE speeds

Verizon Wireless (NYSE: VZ) is currently deploying 4x4 MIMO (multiple ­input and multiple output) technology, involving 4 transmitters and 4 receivers, which the carrier said should enhance both its coverage and improve its LTE network performance. Mike Haberman, Verizon's VP of network support, also said the operator is actively deploying carrier aggregation technology in its 20x20 MHz spectrum channels and expects the effort will allow it to offer spectrum channels wider than a 20x20 MHz configuration in the future, which Haberman said would allow Verizon to offer faster peak wireless download speeds in the future.

Haberman made his comments at the Wells Fargo Telecom Symposium. Wells Fargo analyst Jennifer Fritzsche issued a short report on Haberman's comments. Verizon Wireless representatives declined to offer any details beyond Haberman's comments, and Fritzsche did not immediately respond to FierceWireless questions for details.

According to Fritzsche's report on Haberman's statements, Verizon is working to improve its LTE network with a variety of technologies and strategies, from deploying MIMO and carrier aggregation to building out new small cells, Distributed Antenna Systems (DAS) and macro cell sites. By deploying 4x4 MIMO, Verizon can create a diversity gain that could lead to higher uplink performance. Via carrier aggregation, Verizon can tie together disparate spectrum bands to create wider spectrum channels, thereby quickening download speeds for users.

According to Fritzsche, Haberman said that Verizon now has 20x20 MHz channels supporting its AWS-1 spectrum in most if its major markets. Verizon has branded its AWS-1 LTE buildout as XLTE.

Interestingly, Haberman said that most Verizon cell sites are connected with fiber, but he said Verizon is in the early stages of connecting its cell towers to dark fiber for fronthaul and backhaul. He said dark fiber fronthaul could allow Verizon to deploy a Cloud-RAN (C-RAN) system. C-RAN technology leverages distributed base station architecture to enable a host of benefits, such as capex and opex savings, increased asset utilization and savings on energy.

Verizon isn't the only carrier deploying improved MIMO technology. For example, Sprint (NYSE: S) in Chicago is rolling out 8T8R (8 Transmitters 8 Receivers), multi-layer MIMO and multiple-channel carrier aggregation.

Verizon has made no secret of its efforts to improve its network. For example, during the carrier's recent quarterly conference call with investors, CFO Fran Shammo said that "we are just beginning to refarm 1900 PCS spectrum from 3G to 4G LTE in select markets representing the next phase of spectrum to be deployed to serve our growing LTE usage," he said, according to a Seeking Alpha transcript of the event. "Our network densification plans, which includes small cells, DAS nodes and in-building solutions are on schedule. In New York City we are well into our deployment and continue to scale and develop a healthy pipeline. Downtown Chicago is another large urban market with small cell densification plans well underway."

However, despite Verizon's network efforts, some analysts believe wireless subscribers' increasing demands for data will create problems for Verizon in the coming years. In a research report, analysts at New Street Research said that based on management comments, they estimate that if data growth continues at the current pace, Verizon will run out of capacity in the next two to three years, even if it refarms all 2G and 3G spectrum. "Densification may delay the crunch by a year or two, but sooner or later the company will need more spectrum," said analysts Jonathan Chaplin, Spencer Kurn and Vivek Stalam.

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