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Sunday, January 23, 2011

Will The Real 4G Please Stand Up

it article, mobile, 4G
With the big four wireless carriers (AT&T, Sprint, T-Mobile, and Verizon Wireless) busy shouting the benefits of their current (or upcoming, in AT&T’s case) 4G networks, the casual observer might assume the era of 4G has finally arrived. If you look behind the marketing hype, the real picture is crystal clear. While the 2011 generation of “4G” products offer substantially faster speeds than previous 3G connections, real 4G still has a ways to go. Furthermore, there are numerous impediments to the ascent of this technology that must be resolved.

4G, Where Are You?
Until recently, the International Telecommunications Union held staunchly to the premise that only those standards approved as IMT-Advanced (International Mobile Telecommunications Advanced) could qualify for the designation of “global 4G mobile wireless broadband technology.” The ITU has yet to ratify a 4G specification, with criteria including IP (or digital) communications, flexible channel widths, and bandwidth efficiency to ensure maximum throughput. The most attention-getting requirement, however, has been the minimum download speed of 100Mbps for highspeed mobile access (such as in a car) and 1Gbps for low mobility (such as walking) or stationary access.


In October 2010, the ITU confirmed that two of the six technologies it had evaluated—LTE-Advanced (Long Term Evolution-Advanced) and WirelessMANAdvanced (Wireless Metro Area Networks Advanced) passed their examination. However, critical aspects of both technologies, from radio chips to air interfaces (how the signal enters the phone), remain unconfirmed. Furthermore, the infrastructure required to support 4G is simply not in place, says Chris Kissel, In-Stat industry analyst. “Once you start focusing on speeds, you start cutting away from the network aspects of what is required to make this happen,” says Kissel. “To get to these standards, carriers will have to address a number of hardware and software issues.” As an example, Kissel points to application switching, which (per a proposed 4G spec) is supposed to occur in 50 milliseconds. “None of the current carriers are speaking about that,” he notes. Berge Ayvazian, a senior consultant with research firm Heavy Reading, says there are significant device issues. According to Ayvazian, 4G phones will need multicore processors and Swiss-army-knife chipsets to perform all their duties efficiently. That, he says, isn’t possible quite yet. “We haven’t seen any LTE smartphones [in real-world situations] yet,” he notes. “The Samsung Craft—a first-generation 4G phone—is not very sophisticated. Your experience on the HTC EVO and Epic is better than [with] the Craft.”


Almost But Not Quite 4G
With so many aspects of 4G still in the works, what’s a carrier to do? It doesn’t take a marketing genius to realize that “nearly 4G” simply isn’t going to sell. And yet, carriers’ almost-4G offerings are far faster than their 3G predecessors. What better way to manage this problem than to ignore the ITU completely? That’s what Sprint did when it announced it was testing (in partnership with Clearwire), its WiMAX network in 2008. Top speeds were reported around 3Mbps—hardly 4G, but nearly twice the top speed of AT&T’s 3G network at the time. Sprint has since improved the speeds of its offering, to 3 to 6Mbps average and 10Mbps peak download.

Verizon followed suit in December 2010, rolling out its LTE network in 38 markets and more than 60 airports. Verizon’s network is even faster, offering peak data rates of 40 to 50Mbps and downlink rates of 5 to 12Mbps. This may sound like a far cry from 4G, but consider that the 4G specification is quantified in terms of cell sectors (a subset of a base station’s capacity), not number of users. That 100Mbps average throughput might be distributed among 10 or more users, dropping real-world delivery closer to that of speeds currently marketed as “4G.”


Furthermore, as advocates of the technologies asserted, Verizon and Sprint’s technologies are precursors of LTE-Advanced and WiMAX-Advanced. “LTE is 3.9G—on the road to 4G,” says Ayvazian. “Sprint’s offering (WiMAX) is also 3.9G.” According to Ayvazian, the use of 4G to describe these offerings is understandable, because the underlying technologies are similar

The Bet Pays Off
When T-Mobile began marketing its 4G service in early December 2010, it couldn’t make the same claims as Sprint and Verizon. Its 4G network runs on HSPA+ (aka Evolved High-Speed Packet Access), a technology excluded by the ITU in October from IMT-Advanced approval.

However, in late December, the ITU, which had completely ignored the 4G imposters to date, embraced them all in a single statement: “As the most advanced technologies currently defined for global wireless mobile broadband communications, IMT-Advanced is considered as ‘4G,’ although it is recognized that this term, while undefined, may also be applied to the forerunners of these technologies, LTE and WiMAX, and to other evolved 3G technologies providing a substantial level of improvement in performance and capabilities with respect to the initial third-generation systems now deployed.”

Effectively, the ITU gave after-the-fact permission to carriers to “apply” the term “4G” to their 3.9G technologies. Because a future revision of HSPA+ calls for mobile download speeds of up to 168Mbps and eventually 672Mbps, T-Mobile’s technology was effectively included in the embrace. In reality, T-Mobile’s current service has peak data rates of 21Mbps and downlink rates of 5 to 10Mbps, placing it between Sprint’s and Verizon’s offerings.

More Than Speed
Other than meeting the minimum requirements outlined by the ITU, it’s impossible to say where the final IMT Advanced technologies will end up in terms of speed. According to Kissel, nothing— from base station design to spectrum allocations— is ready for the enormous throughput required to achieve true 4G implementation. Furthermore, issues that seem innocuous, such as the all-digital specification for 4G, loom large on the horizon and will impact business users.

“There isn’t a universal network standard for handling voice transmissions in an IP network,” says Kissel. If one is not in place and adopted by the time 4G arrives (unlikely), phones will need 2G and 3G chips—and suffer the performance issues of toggling between them—to handle both calls and data. “You need all sorts of things in the chipsets to make 4G practical,” he says. ▲

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