Sprint Opens Path to Gig Speeds Over New Mobile Infrastructure

Stephen Bye, CTO & SVP, technology, development & corporate strategy, Sprint

Stephen Bye, CTO & SVP, technology, development & corporate strategy, Sprint

By Fred Dawson
November 27, 2013 – It won’t happen overnight, but the path opened to Sprint through the combination of high spectrum availability, technology advances and infusion of billions in capital from new majority owner Softbank offers a sobering perspective on what’s in store for competitors in fixed and wireless services alike.

“We’re moving into the next chapter of our business with Softbank and our acquisition of Clearwire,” said Stephen Bye, Sprint’s CTO and senior vice president for technology, development and corporate strategy, speaking at an Amdocs event in mid-November. “We’re in the process of ripping out and rebuilding our network. There isn’t a cable or tower we don’t touch.”

With LTE now launched in 230 cities, replacing the short-lived Wi-Max infrastructure, Sprint is gearing up for a broadband wireless service which, utilizing all three spectrum bands under its control, is already operating at peak per-user rates of 50-60 megabits per second in a few places, Bye said. Dubbed “Sprint Spark,” the new infrastructure employs advanced radio arrays in combination with many other technical advances to leverage all the spectrum at Sprint’s disposal across the 800 MHz and 1.9 and 2.5 GHz bands.

New tri-band phones, which allow users to be seamlessly shifted from one band to the next based on local access conditions, are now in the market, including Samsung’s Galaxy Mega and Galaxy S 4 mini and LG’s G2, with the HTC One Max due soon for commercial rollout. Speaking at an investors’ conference in November, Sprint CFO Joe Euteneuer said every Sprint smartphone released next year will operate in tri-band mode, although he noted it remains to be seen whether Apple’s next iPhone will be on that list.

With Sprint Spark now mounted in limited locations in Los Angeles, Tampa, Miami, Chicago and New York, it’s now possible to test Sprint’s claims in real-world environments.

In one such area, namely the Diamond District in mid-town Manhattan, a test conducted on an HTC One Max phone by Gigaom recorded speeds of 43 mbps on the downlink and 17 mbps on the uplink, compared to 4G LTE rates of 16 mbps down/18 mbps up for Verizon and 4.5 mbps down/7 mbps up for AT&T. Tests conducted further away from the Sprint sweet spot in New York by other entities recorded much lower speeds for Sprint Spark but nonetheless found those rates to be well above the rates recorded on Verizon and AT&T networks.

But the real story isn’t about the uniqueness of a 50-60 mbps peak rate, which Sprint says will be available to 100 million POPs by the end of 2014. Other carriers are pushing in that direction as they activate more spectrum on their networks utilizing the same types of advances, such as denser radio arrays, sharing of the same spectrum for downstream and upstream communications via Time Division Duplex (TDD) multiplexing and more efficient aggregation of multiple spectrum channels at a given tier. Verizon, for example, says it will be able to begin offering 50 mbps service once it completes integration of its recently acquired AWS (Advanced Wireless Service) spectrum into its infrastructure.

Where Sprint has an advantage is its ability to leverage more spectrum at the 2.5 GHz tier as it implements new channel aggregation technologies in the years ahead. During a demonstration of Sprint Spark in Silicon Valley on October 30, along with showing downstream speeds of 50-60 mbps at the 2.5 GHz tier on new tri-band devices, the company delivered a 1.025 gigabit-per-second stream using more advanced technology to aggregate multiple channels out of the approximately 120 MHz of total capacity it has available at 2.5 GHz in most markets. Working with Samsung, the carrier simultaneously delivered four Ultra HD (4K) video streams to four TV sets, according to press reports of the demonstration.

The company didn’t speculate on when such capabilities would be commercially available but made clear it’s on a fast track to continually increase speeds as the buildout continues. By late 2015, officials said, the carrier will be able to utilize channels aggregating to 60 MHz to deliver peak rates in the 150-180 mbps range.

With a two-year $16 billion capital spending budget to work with, Sprint is putting money into cutting-edge technology to secure its ability to achieve these gains. In an interview in early November with the producers of the LTE North America conference, John Saw, senior vice president of technical architecture, noted Sprint is the first carrier in the U.S. to deploy radios with eight transmitters and eight receivers, known as 8T8R radios, which represents two to four times more antennas per spectrum band than the current norm.

“These are industry-leading, state-of-the-art radios where we’re able to use carrier aggregation to build some really fat pipes with bandwidths of 40 MHz, 60 MHz and even 80 MHz and beyond,” Saw said. Noting the recent demonstration of 1 gbps throughput, he added, “With our spectrum and technology assets we believe it is technically feasible to deliver more than 2 gbps per sector of over-the-air speed.”

Sprint, of course, is recovering from a troubled history as the third largest mobile provider in the U.S. and remains in rough waters as it overhauls its infrastructure with the dismantling of the Nextel iDEN network and implementation of the 2.5 GHz tier. During a second quarter earnings call on October 30, Sprint CEO Dan Hesse acknowledged the company, which lost 360,000 subscribers during the quarter following a two-million loss in Q1, is experiencing elevated churn as the network modernization project impacts the company’s CDMA call quality and coverage, which will be an ongoing problem through 2014.

A drop off in enterprise customers with the cancellation of iDEN service is also impacting financial performance, although the net of that move, freeing up the 800 MHz tier for LTE, will be positive before too long, officials said.

Moreover, despite the accelerated buildout, Sprint has a long way to go before it catches up with the LTE footprints of its competitors. The carrier expects to cover 200 million POPs on its 1.9 GHz spectrum by the end of the year. In contrast, Verizon’s LTE footprint now covers 301 million POPs, and AT&T is at about 270 million. T-Mobile, the fourth largest mobile carrier, is neck in neck with Sprint at 202 million LTE POPs.

But the balance of power will shift rapidly, Bye asserted. “We’re on a path to rolling this out,” he said. “We see it changing the game in wireless.”