Operators hoping to engage in widespread deployment of voice over LTE in order to gain spectral efficiencies in their network may face some unhappy customers because one vendor's recent tests showed that VoLTE calls can slash a device's talk-time battery life by half.
The study comparing device battery life for calls placed over an LTE network vs. calls placed over a CDMA network was conducted on an unnamed U.S. operator's network in two major markets using a smartphone capable of supporting both CDMA and VoLTE voice calling. "The device's estimated battery life was reduced by 50 percent or about 252 minutes of talk time when voice calls were placed over the LTE network, compared to voice calls placed over the CDMA network," according to the study, authored by Ardeshir Ghanbarzadeh, director, services development, for Metrico Wireless, which was acquired by Spirent Communications in September.
"The significant difference in current drain between VoLTE and CDMA technologies for voice calling applications suggests further optimization of devices supporting VoLTE calls are needed in order to give end-users talk-time battery life expectancy levels similar to that of 3G devices," said Ghanbarzadeh in the report, a copy of which was obtained by FierceBroadbandWireless prior to its public release.
The smartphone tested had a fully charged, lithium-ion 3.7-volt 1540 mAh battery.
Source: Impact of VoLTE on Battery Life, Metrico
CDMA voice-only calls resulted in an average battery current drain of 183 milliamps (mA), and average power consumption of 680 milliwatts (mW). That was about 50 percent less than the power gobbled up by VoLTE calls, which produced an average current drain of 365 mA and average power consumption of 1358 mW.
Interestingly, tests of multi-service simultaneous voice and data calls using just the LTE network revealed 11 percent less current drain than multi-service sessions using CDMA for voice and LTE for data. "This is possibly attributed to the fact that only the LTE radio is in use when using VoLTE/LTE, where as the CDMA radio and the LTE radio are in use when conducting the session in CDMA/LTE," wrote Ghanbarzadeh.
Specifically, the average current drain for CDMA voice combined with LTE data was measured at 889 mA, and the average power consumption at 3280 mW. Employing VoLTE for calls along with LTE for data service produced an average current drain of 790 mA, and 2915 mW of power consumption.
CDMA operators, such as MetroPCS (NYSE:PCS) and Verizon Wireless (NYSE:VZ) have led the charge into LTE and VoLTE as they seek to replace their older 3G technology with something more data friendly and spectrally efficient. In addition VoLTE enables carriers to set up a native mobile VoIP solution the can compete with over-the-top calling services such as Skype and incorporate new features, such as video, into traditional voice service.
MetroPCS became one of the first mobile operators in the world to deploy VoLTE when it launched service this past summer in the Dallas-Fort Worth market. Despite FierceBroadbandWireless' inquiries, the operator did not make a representative available to discuss whether MetroPCS' VoLTE users have suffered from the types of battery-life issues described in the Metrico/Spirent study.
T-Mobile has said it will continue supporting MetroPCS' VoLTE deployments after the two operators' merger closes, likely in the first half of 2013, but has no intention of expanding the VoLTE service anytime soon.
Verizon Wireless CTO Nicola Palmer recently disclosed the operator expects to begin consumer trials of VoLTE in late 2013 with commercial VoLTE service expected in 2014, two years later than initial commercial launch plans. Verizon has indicated a desire to sunset its CDMA networks by 2021.
AT&T (NYSE:T), meanwhile, consistently targeted 2013 for its VoLTE launch. The operator intends to shut down its 2G GSM network by 2017
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