1X Advanced, Rev. B or EV-DO Advanced: The CDMA network migration path is unclear

The name of the game these days is growing network capacity by upgrading to faster data technology. HSPA+ has been successfully bumping up data speeds and giving W-CDMA-based mobile operators more capacity to work with--even as they deploy LTE networks. But for CDMA, moving beyond today's 1xEV-DO Rev. A networks isn't as clear cut.

In fact, there are a number of paths CDMA operators are contemplating to enhance data and voice capacity in CDMA, ranging from simply bolstering voice capacity via 1x Advanced to complementing LTE networks to deploying EV-DO Advanced and EV-DO Rev. B to bolster data capacity and make data transmission more efficient.

Further, Peter Jarich, service director with Current Analysis, said changes like these aren't as straightforward as HSPA+ because operators can pick and choose features from these enhancements.

"For me, the question is, what are the most important features?" Jarich said.

According to the CDMA Development Group, there are 576 million CDMA users across the globe.

EV-DO Advanced, while offering operators a way to improve network performance via a software upgrade, doesn't address peak download speeds. It does, however, improve overall network capacity and latency through techniques such as load balancing, adaptive frequency reuse and single-carrier multilink. Moreover, the upgrade is compatible with existing Rev. A devices.

1X Advanced builds on 1X technology and adds techniques such as BTS interference cancellation, radio link enhancements and others to provide boosts to performance including up to a 4x increase in voice capacity and up to a 70% increase in coverage.

Rev. B, also referred to as multi-carrier EV-DO, can also be accomplished via a software upgrade in the first phase by combining three carriers together in a 5 MHz channel to deliver a peak download rate of 9.3 Mbps, and peak upload rates of 5.4 Mbps. Phase II requires a hardware upgrade with a new channel card at the base station that supports 64 QAM modulation and improved interference cancellation. Peak download speeds jump to 14.7 Mbps.

While the technology has been talked up since 2007, the CDMA Development Group reports that some nine commercial Rev. B networks are up and running around the world. For most CDMA operators in the U.S. though, which comprise a large part of the world's CDMA subscribers, enhancements are taking a back burner to LTE deployments. Nonetheless, it's clear CDMA will be a fill-in and voice solution for some time.

"CDMA is an end-of-life technology, but in saying that, like any technology, it will take a long time before it disappears," said Phil Marshall, head of Tolaga Research. "In the interim there are solutions like 1x Advanced that allow service providers to squeeze more out of the technology without necessarily making massive capital investments."

Verizon Wireless and the future of CDMA

Verizon Wireless' (NYSE:VZ) network roadmap is clearly focused on LTE. When asked about CDMA upgrades, Verizon spokesman Jeffrey Nelson said the operator hasn't announced any plans to deploy CDMA upgrades and reiterated that the company's LTE network now covers more than half of the nation--160 million people--and that the company is on track to cover its existing EV-DO footprint with LTE by the end of 2013.

Sprint Nextel focuses on LTE, plans for 1X Advanced

Sprint Nextel (NYSE:S) recently announced plans to undertake an aggressive rollout of LTE, with the operator's initial LTE markets turned on by mid-2012. To accomplish this, Sprint will initially roll out LTE in the G-block of the 1900 MHz band, where Sprint has a nationwide 5X5 MHz block of spectrum. Sprint's G-Block spectrum will be combined with other 1900 MHz spectrum for its LTE service; the carrier currently has an average of 20-25 MHz per market nationwide in 1900. At some point in the future, Sprint also plans to use its 800 MHz for LTE; the carrier currently uses 800 MHz for iDEN but will begin moving those customers off that spectrum by 2013.

Sprint also plans to deploy CDMA 1X Advanced voice service in its 800 MHz spectrum--where it will decommission the iDEN network--and move EV-DO Rev. A traffic off its 1900 MHz spectrum into the 800 MHz band, presumably incenting subscribers to buy LTE phones and leveraging the new CDMA network for voice.

MetroPCS plans EV-DO investments

MetroPCS (NYSE:PCS) doesn't have a widespread 3G EV-DO network. Instead, the company decided to move straight from a CDMA 1X network to LTE. Nevertheless, the firm is deploying some EV-DO in its cell sites to augment its CDMA 1X service. The operator could opt to include 1X Advanced down the line to bolster voice capacity until Voice over LTE becomes widespread.

A global move to Rev. B

For many competitive markets where HSPA+ and LTE are competing, a move to Phase 2 of Rev. B makes little sense because these technologies' peak data rates exceed Rev. B's 10 Mbps peak rates, making this hardware investment of little value to operators, said Daryl Schooler, principal analyst with Ovum.

However, EV-DO Rev. B and other CDMA data enhancements are gaining a foothold in markets where LTE and HSPA+ deployments are sparse or non-existent.

Emerging economies represent areas where spectrum is typically not available for LTE at the moment, but users are hungry for affordable data services. For instance, two of India's operators--Sistema Shyam Teleservices Ltd. and Tata Teleservices--have deployed Rev. B in the 800 MHz band, while a number of CDMA 450 operators have deployed the technology.

MBlaze Ultra

MBlaze Ultra

SSTL recently declared that it is deploying the world's first Rev. B Phase II network. The company plans to roll out the advanced Rev. B Phase II network to top metro area and other key cities across India, and it is also introducing the MBlaze Ultra--a dongle capable of providing data download speeds of 9.8 Mbps, the company said.

China Telecom, which is now the largest CDMA operator in the world, has stated its intention to deploy Rev. B, but has yet to move beyond its trial phase. A move by China Telecom to Rev. B would drive the ecosystem and scale the technology on the infrastructure and handset side. China Telecom will be rolling out LTE.

"We have several customers that have deployed commercially," said Leonard Pesheck, director of wireless communications with Alcatel-Lucent (NYSE:ALU) . "We continue to wait on what China is going to do beyond trials ... While customers are deploying, it's not going as quickly as we hoped, and the Tier 1 customers, except China, have not embraced it."    

1X Advanced, Rev. B or EV-DO Advanced: The CDMA network migration path is unclear