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Mobile WiMax Chips

Unstrung’s Gabriel Brown says chipset developers and equipment providers are jockeying for position for Mobile WiMax. Mobile WiMax will be here in 2007-2008, but it will be a very different animal than fixed 802.16-2004, available at the end of 2005.

There are really two kinds of WiMax: Fixed WiMax and Mobile WiMax, explains Brown.

“A key feature of 802.16e that makes it suitable for mobile applications is the introduction of “scaleable OFDMA” (orthogonal frequency-division multiple access) to the air interface, as well as related enhancements, such as power-save mode.”

“WiMAX is going to give you a box for 200 bucks that does voice and data,” says David Sumi, marketing vice president at TeleCIS. “As a service provider, I can get $20 out of you for data and another $20 out of you for voice. And if I have a cost of $200 for the box to hook you up, and many of my customers will be self-installed, now I have a business case.” TeleCIS plans “dual-mode”, WiFi/WiMax chipsets.

Mobile service to laptops/PDAs will expand the WiMax market, perhaps by an order of magnitude larger in both units and revenue. With smart antenna technology and more rugged protocols, Mobile WiMax is expected to deliver more robust signals, reducing the effects of interference, while enhancing speed and range.

Mobile WiMax is focused on the concept of personal mobile broadband, standardized by the IEEE 802.16 Task Group E (802.16e), and also known in Korea as WiBro. But although it is often pitched as complementary to wireless LAN and 3G cellular, one of the driving motivations behind Mobile WiMax is to develop an open technology platform that outperforms 3G, is more suited to an all-IP network architecture, and has less onerous intellectual-property licensing terms.

It s hard to judge if widespread adoption of the Mobile WiMax platform is a realistic objective, but if it even halfway meets expectations, investors and major equipment vendors know they can t risk being left on the outside.
For startups, Mobile WiMax is an opportunity to leapfrog the market for Fixed WiMax systems (based on IEEE 802.16-2004 specifications), which they see as suffering from designed-in obsolescence.
This report identifies and analyzes the chipsets and system vendors innovating in this critical, long-term market and plots the long-term convergence of WiMax with cellular systems.

The report mentions new WiMax chip vendors such as BeeCem and Aspex as well as well as WiMax chips from Intel and Fujitsu and other chip vendors such as Adaptix, PicoChip, Sequans, Wavesat, TeleCIS, Runcom Si-Wave and Cygnus. TeleCIS and Sequans are implementing new options available in WiMax inside their chips. Fujitsu and Intel are also positioning themselves for upward mobility. WiMax Trends has a comparison table of the chips.

Mobile WiMax Chips

Source: Company web pages

Company

Year Founded, Location

Description

Chips or no chips, Unstrung’s Insider is none to enthusastic about Mobile WiMax:

Apart from rare exceptions (Korea), we don t expect to see nationwide, or even many city-wide, mobile WiMax networks rolled out for mass-market services in either the near- or medium-term.”Furthermore, by the time WiMax is commercialized, it will be competing with enhanced 3G systems — such as HSDPA and CDMA 2000 1x EV-DO Rev A — that are expected to improve the data speed of existing cellular technologies.”

Why is 802.16e Incompatible?

A CDMA-sponsored White Paper (pdf) explains why 802.16e will not be compatible with 802.16-2004. Fixed WiMax (802.16-2004) typically utilizes 256 OFDM carriers, serving multiple users in a time division fashion in a sort of a round-robin technique. It’s done quickly so users have the perception that they are always transmitting/receiving. Like WiFi.

(pdf) explains why 802.16e will not be compatible with 802.16-2004. Fixed WiMax (802.16-2004) typically utilizes 256 OFDM carriers, serving multiple users in a time division fashion in a sort of a round-robin technique. It’s done quickly so users have the perception that they are always transmitting/receiving. Like WiFi.Mobile WiMax using 802.16e is different. It uses Orthogonal Frequency Division Multiple Access (OFDMA), and can serve multiple users simultaneously by allocating sets of “tones” to each user. The 128-2048 carriers of Scalable-OFDMA can be divided into “subchannels” using only a segment of total carriers. These can transmit simultaneously. That also improves the QOS capacity for voice calls.

Subchannelization was added into 802.16-2004, but the requirement for simultaneous upstream access required a much more robust base station, and “broke” the compatibility of plain vanilla 802.16 which generally uses 256 “fixed” OFDM carriers. It allows a subscriber station to concentrate its transmit power on a subset (subchannel) of the total OFDM subcarriers. That leads to stronger uplinks, better coverage range and capacity.

The primary reason for incompatibility with fixed 802.16-2004 is that 802.16e uses S-OFDMA (scalable-OFDMA) in both the uplink and downlink channels to enable simultaneous multiple access (OFDMA). Additionally, the 802.16e MAC layer introduces new header information that is essential to support mobility (cell handoffs, etc). Even if there was a 256 tone option with 802.16e, the differences between the two MAC layers would prevent the fixed and mobile versions from working together.

Parameters	Values

* variable set only
** FFT size of 256 is not supported

WiMax System Performance

Range

< 4 miles

4-6 miles

> 6 miles

But spectrum availability and regulation will impact the future of mobile broadband wireless — perhaps more than chips. Nancy Gohring reviews the spectrum available for WiMax.

Telecoms Asia says without a density of at least 100 potential subscribers per square kilometer (.38 square miles), it is difficult to justify the cost of building and maintaining the network.

Ovum estimates the incremental cost of deploying a four-cell base station to be $50,000. Based on an ARPU of $40 per month and a simplistic two-year payback period, over 52 subscribers are required. This is just the payback for the capital cost. It does not include operating expenses, interest, shared overheads etc. In Sydney the average number of households per square kilometer is 127. This suggests that a local operator like Unwired would require a market share of close to 50% in the areas where it has coverage.


“Typical cellular systems broadcast radio-frequency energy over wide areas. The only useful part of that energy, however, is the part that impinges on the antenna of a connected user.All the rest of the broadcast energy is not only wasted, but it causes interference”. - Martin Cooper, Arraycomm

Still, $40K per base station seems excessive as does a 2-year payback. Couldn’t one, $5K WiMax mini basestation illuminate at least one square mile? And wouldn’t a 3-year payback period be typical?

Covad will be one of the first to launch a fixed WiMax-like service, probably at 5.8 GHz. Covad delivers 5 Mbit/s service up to 5 miles from their base stations — impossible with DSL.

Alcatel says a WiMAX base station operating at 3.5GHz has the same coverage as a 2.1GHz 3G base station, but is 30% cheaper. Most studies indicate WiMax service will be significantly cheaper and faster than cellular…and it can provide fixed broadband service for VoIP.

Proprietary 3G gear is expensive and lacks capacity. Many municipalities plan to save money by building their own networks. WiMax, with ten times the range of WiFi, is expected to be cheaper per user than any alternative.

Meanwhile, Personal Broadband Australia, which uses the 1.9 GHz band and Arraycomm technology (above) is working with Intel on 802.16e clients. Sydney’s PBA iBurst service is expanding to Melbourne, Brisbane, the Gold Coast, and Canberra within the next three months.

Unwired Australia (coverage map below) uses the 3.5 GHz band for its Navini-based system, and will eventually evolve to mobilized WiMax. Unwired wants to expand nationwide but lacked frequencies. This week AUSTAR announced an agreement to trade a portion of its 2.3GHz spectrum licences to Unwired.

Navini’s WiMax client will be available by year’s end, with a PC Card in 2006. The Ripwave-MX basestation, targeted for 1st half of 2006, will be software upgradeable to 802.16e and will continue to support the Smart Antenna functionality.

Unwired Australia says they’ll break even with 50,000 subs. They’ve got 25,000 after year one.

Both Navini and Arraycomm are pioneers in “smart” and “adaptive” antenna technology, so their implementations in Australia will be closely watched — especially as it pertains to mobile WiMax.

Will Mobile WiMax threaten cellular operators? Cellcos say no. Telcos say yes.

Broadband Wireless trials from Major U.S. Carriers include:

AT&T In the fourth quarter, AT&T is launching a commercial trial in Atlanta using pre-certified gear from multiple WiMAX vendors. AT&T also launched a technical trial in Middleton, N.J.
BellSouth BellSouth is expanding its broadband wireless trial using Navini Ripwave gear to Athens, Ga., and two Florida communities by the end of the year.
Qwest Communications In the fourth quarter, Qwest is planning to launch a trial in a community near Denver using an unspecified vendor’s kit.
Verizon Avenue Verizon’s alternative access subsidiary Verizon Avenue launched a trial broadband wireless network in Grundy, Va., last year using Alvarion’s BreezeAccess gear. Though Verizon owns WCS spectrum it chose to use unlicensed frequencies for the trial.

Most 3G cellular systems (and Flarion) use Frequency Division Duplexing. FDD requires two channels, one up and one down. It’s why cell towers have two antennas on each sector. FDD is often used for voice, because the bi-directional architecture allows voice to be handled with minimal delays. But FDD adds additional components and costs.

WiMax systems can use FDD, but most implementations use a single channel with Time Division Duplexing. TDD can be more efficient (one channel isn’t “idle”) and TDD makes “smart” antennas practical, boosting range and speed. Simultaneous “conversations” can be enabled with subchannelization.

The Real Deal

In a competitive, broadband climate, telephone companies would have access to licensed 2.5 GHz frequencies. But they don’t. Qwest, Verizon, SBC and Bell South, failed to bid on them.

Sprint-Nextel and Clearwire did. They call the WiMax shots in the United States. Only Clearwire (and Aloha Partners) can provide real competition. Sprint won’t undercut their own cellular service.

U.S. Telcos and independent WISPs will be forced to use the unlicensed band. The DSL/Cable duopoly will control wired broadband. Cellular’s speed/cost isn’t competitive. WiMax, therefore, won’t make a dent in U.S. competitiveness.

In the U.S., only Sprint and Clearwire (with partners) are mobile WiMax candidates. Asia is the real deal. It may also be why 802.16e is essentially WiBro, with little backwards compatibility to the fixed 802.16-2004 standard.

Still, it does seem that the WiBro approach is pretty slick.

- Sam

Telco politics and AWAC radar at 3.5 GHz didn’t help.

Perhaps the newly allocated H block frequencies at 1915-1920 MHz (previously used for unlicensed PCS) and 1995-2000 MHz (previously assigned to MSS operators) will improve the situation. Other frequencies opening up include the 2020-2025 MHz and 2175-2180 MHz bands and an auction for Advanced Wireless Services (1710-1755 MHz and 2110-2155 MHz). An auction could happen as early as June 2006.

If those frequencies were offered as a national license, (valued about $5 billion), then real mobile broadband competition might be available in the United States. The Lower 700 MHz Band using Blocks A, B & E, have not yet been auctioned; broadcasters are holding it up. The 700 Mhz band penetrates extremely well but capacity is a problem. The 6/12 Mhz blocks (at 700Mhz), have less capacity than the 2.5Ghz band or the unlicensed 5.8 GHz band which has 100 Mhz available.

Adaptive antenna systems (AAS) are an optional part of the 802.16 standard. These antennas have beamforming properties that can steer their focus to a particular direction or directions. That may (eventually) make the unlicensed 5.8 GHz band a contender for mobile WiMax. But overcoming the laws of physics at 5.8 may be a tough nut to crack.

Is it economically and technically viable to provide 1-3 Km range (or more) in a Handset/Laptop card using 5.8Ghz? Who knows? Bandspeed (above) claims both omni and spatial-division sectorization. Intel likes SDMA with transmit diversity. Skycross embedded antennas are used in Samsung’s Digital Multimedia Broadcasting phones.

The new bells and whistles of 802.16-2004 (pdf), provide an indoor range of 1-2 Kilometer (at 3.5 GHz). So perhaps outdoor handsets or PC cards (at 5.8 GHz) might get 1km. Perhaps more with mobile WiMax adaptive antennas. With one every mile or so, getting the cost of these 5.8 GHz WiMax “hotspots” down to $5K-$10K might be the trick.

“There’s nothing that precludes the use of WiMax on the LAN,” says Mike Librizzi, vice president of marketing at Cygnus Communications, a WiMax silicon vendor that demonstrated a software-defined WiMax system at the SuperComm show last month. “You will get an improvement in data rate, and a service that can stream to multiple devices.” In the unlicensed 5.4-GHz band, low-power WiMax equipment could be used under just the same restrictions as Wi-Fi, but with several benefits, according to Librizzi.

Implicit in that statement is the belief that WiMax gear will be commonitized, and priced similarly to WiFi gear.

In 2002, Korea’s IT industry accounted for about 15 percent of gross domestic product, higher than the 8.3 percent of the U.S. By the end of 2005, virtually all Korean households will be able to access broadband. They’ll get national mobile WiMax starting a year from now.