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Jumble of network formats seen in 4G

Posted: 16 Jan 2007 ?? ?Print Version ?Bookmark and Share

Keywords:4G? wireless? WiMAX? cellphone? WiBro?

Technologists are sparring with bean counters over what 4G should look like to yield the best service for customers and the best return for operators. But even as the voices defining 4G standards swell in cacophony, the debate itself may be declining in importance. That's because networks almost certainly will be based on an alphabet soup of formats, with nothing in the way of an overwhelmingly dominant technology.

The most surprising contender for 4G has been 802.16 WiMAX, originally seen as an independent, Internet Protocol (IP)-based broadband wireless standard for local or regional use. When Sprint announced a national WiMAX footprint in the U.S. last year, the company decided to call its network 4G, positioning it against Evolution Data Optimized or 1xEV-DO. The semantic shift wasn't lost on competing wireless operators and market analysts.

When operators make a single bet, especially on an emerging spec like WiMAX, it's often tough to win. Making multiple bets is complicated but typically holds the best chance of success. Attaining high-speed 4G ubiquitous connectivitythe nirvana of anytime, anywhere, on any devicewill have some operators scrambling to stitch together a hodgepodge of radio networks. At the same time, they will need to coordinate with system designers on the introduction of increasingly complex devices, ranging from PDAs and ultramobile PCs to cellphones and high-end CE.

"4G to me is not about the next radio link; it is much more about how you deal with a set of heterogeneous networks and get bits to and from the device in the most cost-effective way," said Paul Jacobs, chief executive of Qualcomm Inc.

Qualcomm talked up its 4G contender in December, saying that cdma2000-based 1xEV-DO Revision C will be released in Q2 and become commercially available in early 2009. Officially named Ultra Mobile Broadband, it can theoretically support mobile data speeds of up to 280Mbps, using multiple-input, multiple-output (MIMO) antenna technology and scalable bandwidths up to 20MHz.

'4G lite'
Others in the industry are looking at how WiMAX and 3G, or maybe even Wi-Fi, might mesh to form a "4G lite" in the near future. Data rates would fall short of the 100Mbps downlinks and 50Mbps uplinks for every 20MHz of spectrum that hard-core engineers would consider full 4G strength, but users would see gains over today's 3G speeds.

"Many of these technologies will have leverage and advantage," said Mohammad Shakouri, VP for strategy at Alvarion Ltd, an Israeli developer of WiMAX, "so instead of trying to find one killer application or one technology that solves everything, what we should be doing is trying to figure out how to leverage a combination of these technologies."

Some emerging devices do just that. Samsung's SPH-P9000 Deluxe Mobile Intelligent Terminal, for one, is a PC shaped like a PDA, with a collapsible keyboard, Windows XP, 30Gbyte hard drive, 256Mbytes of RAM, 5-inch display and 1GHz Transmeta CPU. It supports WiMAX and EV-DO.

Attaining the nirvana of 'anytime, anywhere, on any device' will have some operators scrambling to stitch together a hodgepodge of radio networks.

Optimistic forecasts say WiMAX could nab 9 million subscribers worldwide by 2009, not counting infrastructure applications in cellular backhaul. Thanks in part to South Korea's familiarity with WiBro, a pre-WiMAX service, close to half of those subscribers will be based in Asia. Samsung believes the WiMAX market will be worth $3.9 billion in 2010, with subscriber numbers growing to 25 million by 2011.

Yet there are some concerns that not enough phones are in development to drive the uptake of heterogeneous networks that include WiMAX. "Limited options for dual-mode end-user devices raise question marks over the pick-up of WiMAX technology," said Qiang Cao, VP of the mobility division at ZTE Corp.

Chip and system makers also need to improve the throughput of WiMAX and WiBro, especially in small portable devices.

"We definitely still need to see an increase in average throughput," said Kim Dong, a manager on SK Telecom's access network development team.

SK is one of few operators that have commercially deployed 802.16e as part of a wider plan to gain ubiquitous high-speed coverage through WiMAX, high-speed downlink packet access (HSDPA) and Wi-Fi.

Cost constant
There are many factors that argue either for or against WiMAX as a complementary technology to 3G, said ZTE's Cao. "However, there is one constant in this debate, and that is cost," he said. "WiMAX is a more cost-efficient solution, at least for now.

Part of the convergence story will play out in chips. Right now, only a few companies are trying to push convergence at the silicon level, since the market is young.

Comsys Mobile will have samples of its WiMAX baseband late this year, with a 2.5G/WiMAX baseband arriving in April 2008, said Ronny Gorlicki, executive VP of sales at Comsys Communication and Signal Processing Ltd.

Kazihiko Yamaguchi, a WiMAX engineer at Fujitsu, said Fujitsu's customers aren't thinking yet about converged WiMAX/cellular silicon platforms.

"One of the reasons we aren't seeing a strong push for integration," SK's Park said, "is that there are not any operators out there using itjust us."

Chipmakers will move to an SoC that includes all radio access technologies.

That will change in late 2007 and early 2008, as momentum builds in South Korea and commercial rollouts in the United States gain traction, said Hwan Woo Chung, VP of Samsung's Mobile WiMAX group. Japan and the United Kingdom are also due to decide on whether to use WiMAX.

Even Qualcomm's Jacobs, no fan of WiMAX, said his company is open to using it if deployments gain momentum in the market during the next few years. "Maybe we would do it by means of an acquisition, maybe by means of a partnership or maybe by means of internal development. But right now it is not our highest priority, because we just don't believe the technology is that good," he said.

Some operators will need more persuading before investing in a WiMAX network. Some will prefer to follow the HSDPA/HSUPA path laid out for Universal Mobile Telecommunications System service in 3GPP Release 5, which aims to achieve peak data rates of 14.4Mbps. Using MIMO and beam-forming technology, Release 6 targets theoretical throughput of 28.8Mbps.

Regardless of the access technology chosen, operators know they need to push forward on achieving all-IP networks. "We talk a lot about 2G, 3G, 4G, WiMAX, etc., but I might argue that it doesn't matter, because they will all be there," said Patricia F. Russo, chairman and CEO of Lucent/Alcatel. "What matters is what you do at the core of your network that enables you to deliver these services in an access-agnostic way, in a device-agnostic way."

- Mike Clendenin
EE Times

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