Computerworld - A long-term battle is brewing between two emerging high-speed wireless technologies, WiMax and Long Term Evolution (LTE). Each would more than quadruple existing wireless wide-area access speeds for users.
The two technologies are somewhat alike in the way they transmit signals and even in their network speeds. The meaningful differences have more to do with politics -- specifically, which carriers will offer which technology, as in the recent skirmish between backers of Blu-ray and HD video.
In this coming wireless war, one technology won't necessarily obliterate the other, but analysts believe LTE will have a tremendous upper hand overWiMax in coming years, primarily because carriers on the GSM standard (Global System for Mobile communications) predominate around the globe and will use LTE as their upgrade pathway. GSM is the most popular mobile communications standard.
LTE will dominate, analysts believe, despite the recent attention generated by plans for a joint venture between Sprint Nextel Corp. and Clearwire Corp. for a national WiMax network that is expected to reach 120 million to 140 million people in the U.S. by the end of 2010. Even though Sprint officials admit that's an ambitious goal, they believe they have a clear time-to-market advantage over LTE in the U.S., by perhaps a year or more.
So far, AT&T Inc. and Verizon Wireless, the two biggest wireless carriers in the U.S., have stated plans to adopt LTE, with major rollouts planned for 2011 or 2012. And, in a surprise to many, even Sprint has not ruled out building LTE and is not prevented from doing so by its joint venture plans with Clearwire and several major investors including Google Inc., Intel Corp. and three cable companies.
"WiMax and LTE are directly comparable in terms of what they do, and it's very likely LTE will have a significant global advantage over WiMax in the long term," said Craig Mathias, an analyst at The Farpoint Group and a Computerworld columnist. "But that doesn't mean WiMax is toast or won't survive, although I'm not even sure of [Sprint's] expected time-to-market advantage when we talk about critical mass penetration.
"LTE is the natural upgrade path for GSM, and that leads me to conclude that LTE will be one tough cookie for WiMax to beat," he added.
The GSM family will account for fully 89% of the global market in 2011, according to Gartner Inc. In the U.S., AT&T is a GSM provider, along with T-Mobile, which many believe will eventually announce intentions to support LTE.
WiMax vs. LTE
| WiMax | LTE | |
|---|---|---|
| Maker of standard and year | 802.16e (mobile) in 2005 from IEEE | Second half of 2008 from 3GPP |
| Current U.S. Pilots/Trials | Baltimore, Chicago and Washington | U.S. (sites not disclosed), Europe and China |
| Mass market availability | Late 2010 | 2011-2012 |
| U.S. carriers and investors | Sprint now; but proposed Clearwire joint venture with Sprint includes investors Google, Intel and three cable companies | AT&T, Verizon Wireless |
| Technical capabilities | Multiple Input-Multiple Output (MIMO) Downlink: Orthagonal Frequency Division Modulation Uplink: OFDM | MIMO Downlink: OFDM Uplink: SC - FDMA (Single Carrier- Frequency Division Multiple Access) |
| Speeds | In soft launch: 2Mbit/sec. to 4Mbit/sec. average download; 10Mbit/sec. peak download 70Mbit/sec. theoretical max | 100 Mbit/sec. theoretical max |
| Radio Spectrum expected | 2.5 GHz | 700 MHz |
The players
In addition to the carriers, there are standards groups and manufacturers driving the two technologies. So far in the U.S., Sprint and Clearwire are aligned behind WiMax, while Verizon Wireless and AT&T are behind LTE.
Still, as of now, LTE is not even a set standard. However, that status might be conferred on LTE in the last half of this year by a group of vendors calling itself the 3GPP (Third Generation Partnership Project), Redman said.
LTE is in trials in the U.S., Europe and China, according to a Verizon spokesman, who refused to divulge the U.S. location or any other details.
The IEEE (Institute of Electrical and Electronics Engineers Inc.) picked 802.16e as its mobile WiMax standard in late 2005, and that is the standard Sprint began deploying last fall in three markets -- Washington, Baltimore and Chicago -- in what it has begun calling a "soft launch," with its employees as users. The carrier still has not officially announced a commercial service timetable.
A group called the WiMax Forum, made up of more than 500 vendors and other members, has established itself as an authority to certify WiMax gear. In April, it announced the certification of eight WiMax products for use in the 2.3 GHz band, with products in the 2.5 GHz band expected to be certified later this year.
As for equipment manufacturers, Intel has invested billions of dollars in WiMax research and chip sets and showed off conceptual mobile Internet devices at the Consumer Electronics Show in January. Motorola Corp., among a long list of manufacturers, has been a strong proponent of Sprint's WiMax initiative, but it also will be developing LTE technology.
The speeds
How will LTE and WiMax perform? The big technology focus of both approaches has been on speed, or throughput, to the user. Theoretical maximums for WiMax are listed in textbooks at 70Mbit/sec., while an AT&T official boasted LTE will provide speed of 100Mbit/sec.
Such speeds would greatly enhance video transmissions and online gaming. For business users, they could offer lightning-fast access to enormous corporate data stores sent over encrypted channels. Some futurists believe both technologies could bring about wireless video phone calls, like the ones Dick Tracy receives on his watch. Today, by comparison, videoconferencing from a wired desktop is still relatively expensive and not always reliable without a high-speed wired connection.
The speeds expected by both LTE and WiMax are hard to nail down primarily because the technologies are just rolling out. Many factors will be taken into consideration, including whether a carrier plans to send the signals over a wireless channel that is 40 MHz in width, double the standard 20 MHz channel, noted analyst Philip Solis of ABI Research Inc.
Speed to an end user is also dependent on how many users are connected to a cell tower, how far away they are, what frequency is used, the processing power of the user's device, and other factors.
A Verizon spokesman wouldn't offer any predictions on what speeds LTE could deliver. "I'm not saying anything on that," said the spokesman, Jeffrey Nelson. "Not theoretical or advertised speeds or what's proved out in the real world."
At Sprint, a spokesman said conservative estimates of the WiMax downlink speeds will be 2Mbit/sec. to 4Mbit/sec. on average on the Xohm WiMax network that Sprint is building, with 10Mbit/sec. peak downlink speeds. For uplinks, the speeds will average 1Mbit/sec. to 2Mbit/sec, depending on the processing power of the user's device.
The same, yet different
There are some notable technology differences between LTE and WiMax, but analysts said both approaches have much in common.
For example, both technologies provide the same approach for downlinks, and both have Multiple Input Multiple Output (MIMO), which means that information is sent over two or more antennas from a single cell site to improve reception. In tough transmission locations, such as a dense downtown area, MIMO could be a relatively inexpensive means of improving reception to users.
The downlinks from the cell tower to the end user in both LTE and WiMax are enhanced with OFDM (Orthogonal Frequency Division Multiplexing), a technology that supports sustained video and multimedia transmissions and is already being deployed in some non-LTE and -WiMax networks. It works by splitting up signals among multiple narrow frequencies, with bits of data sent at once in parallel. Needless to say, it is complex technology that will require sophisticated base stations, an added expense even for those carriers that see LTE as an upgrade path to GSM, analysts said.
"Although LTE is on the GSM track, it really requires new equipment" at base stations, said Lisa Pierce, an analyst at Forrester Research Inc. That means a substantial investment is in store for AT&T and also for Verizon, which has focused on CDMA (Code Division Multiple Access), but partners with Vodafone, a GSM carrier favoring LTE. The cost of a national WiMax network will be billions of dollars, and an expenditure of that much money would not have been possible without the Clearwire-Sprint joint venture.
Uplinks from the user to the cell tower will probably be different in the two technologies. OFDM will be used in WiMax, but a technology called SC-FDMA (Single Carrier-Frequency Division Multiple Access) will be used in LTE, Solis said. SC-FDMA is theoretically designed to work more efficiently with lower-power end-user devices than OFDM is.
Both technologies will be IP-based, which will enable quality-of-service technologies to be applied, although it is not clear whether carriers will offer guarantees of service to business users. The big push for WiMax has been with consumer-based devices so far, and service guarantee considerations have been secondary.
"How much differs between LTE and WiMax remains to be seen, since LTE is not standardized yet," Pierce said. LTE is designed to turn voice and data traffic into packets, which bodes well for unified communications applications, she said. In theory, WiMax will also be able to support voice, but whether it is used for voice "remains to be seen."
José Galviz 17.206.921
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