The wireless infrastructure industry can expect to deploy significantly more cell sites as voice over LTE is implemented, James Taiclet, president, CEO and chairman of American Tower, told the first quarter earnings call.
“Based on recent independent technical assessments that we’ve commissioned, we now believe that VoLTE will result in significant network densification or cell splitting for coverage in suburban, highway and rural areas,” Taiclet said. “We believe VoLTE is likely to necessitate further network densification even beyond data as we move forward, and we think it presents significant opportunities for tower leasing as VoLTE is deployed.”
Because the current LTE network architecture doesn’t include traditional 2G/3G voice services, carriers must move beyond data-only LTE to provide voice and SMS alongside LTE mobile broadband, Taiclet said. Circuit-switched networks that carry voice will be converted to all-IP VoLTE networks. Carriers will benefit from cost advantages and greater spectral efficiency.
“By utilizing VoLTE, carriers can achieve increased efficiency regarding their wireless spectrum and also eventually reassign some of this spectrum to 4G data and entertainment services,” Taiclet said. “And finally, for CDMA providers like Verizon, VoLTE will allow simultaneous voice and data sessions on phones with the single chipset, thereby improving the user experience while reducing device costs.”
Taiclet said Verizon and AT&T are expected to complete phase one of their initial LTE overlays on their existing networks within six to 12 months, while Sprint and T-Mobile are expected to finish in 18 months to two years. Phase one has consisted of 80 percent amendments and 20 percent new collocations.
“However, given that LTE handset penetration is currently below 10 percent in the United States, phase one networks will simply not be able to keep pace with the volume of data that will be generated as more consumers switch to high-bandwidth 4G handsets and tablets,” Taiclet said.
In phase two of the LTE buildout, carriers will focus on increasing capacity and improving signal quality at the edges of existing cells through cell splitting and network densification. Verizon has indicated that it will begin implementing VoLTE in the next 12 months.
VoLTE requires more towers, Taiclet said. The packet-switched nature of VoLTE is more vulnerable to signal degradation than an LTE data session or a circuit-switched voice session.
“In a typical data session over LTE, a subscriber moving away from a cell site can usually handle some degree of signal degradation,” Taiclet said. “Conversely with a voice over LTE, the listener must continuously be able to comprehend what the person on the other line is saying in order for the session to be successful. Therefore, the quality of service requirement is elevated, especially at the outer ranges of cell sites.”
To avoid garbled or dropped voice calls, the effective radius of a VoLTE cell site could be reduced by 10 to 20 percent, Taiclet said. So cell sites must be closer together.
“The exact amount of further cell site identification to deliver high-quality VoLTE service depends on a number of factors, including existing network layout and spectrum characteristics,” he said. “But our initial estimates indicate that networks may ultimately have to be up to 20 to 30 percent more dense than an already densified data-only LTE equivalent network.”