WiMAX Watch: Trials
>> WiMAX Trials Give New Hope for Broadband Wireless Specialists
Wireless Watch
2 October, 2003
rethinkresearch.biz
Trials of WiMAX-ready equipment for broadband wireless access (BWA) are coming thick and fast as operators test the real world capabilities of the standard in preparation for 2004 roll-outs. And the new cost-effectiveness of building powerful metro area networks will have a knock-on effect on some previously sidelined backbone technologies, giving them a new lease of life in backhauling WiMAX and linking WMans to form national networks that really could challenge 3G.
The history of broadband wireless has been largely one of disappointment to date. Pioneers like Teligent, Nextlink and Winstar entered the market in the late 1990s with networks based on cost effective LMDS (Local Multipoint Distribution System), but they played safe and stayed in over-served metro areas of the US rather than remote regions, and having paid huge federal fees for their licenses, all three companies filed for bankruptcy. Carriers such as MCI and Sprint invested in an alternative, MMDS (Multi-channel Multipoint Distribution System) but failed to gain significant market momentum – although BellSouth continues to push the technology, and announced trials in two rural North Carolina counties this week using its 2.3GHz licenses.
These trials are partly funded by the US Rural Internet Access Authority, whose remit is to bring broadband access to the most remote areas of the country, but increasingly it is looking to WiMAX as its best option. The influence of such bodies on the fixed wireless sector’s directions is immense and many of the significant authorities, including the US and Chinese bodies, are increasingly favoring support for 802.16a proposals because of the relatively low build-out cost and major vendor support. The importance of these authorities is illustrated by Intel’s appointment of a director of rural broadband, whose role is primarily to talk up 802.16a to the Access Authority and its equivalents in other countries.
The role of these public bodies may decline as BWA, for the first time, gains the potential to support free market operators without subsidies, because of the lower cost of equipment, higher demand for broadband data (and possibly voice) services and the availability of commodity silicon. For instance, while the US government plans to award $11.3m in broadband grants to 34 rural communities in 20 states in the coming year, to enable them to provide residents with computers and internet access, the Bush administration has cut back significantly on the funding for rural broadband. Its proposed 2004 budget calls for cutting the $20m total rural broadband grant program to $2m next year. The government argues that rural subsidies deter operators from investing in rural areas, and that a freer market would speed the adoption of 802.16a. For instance, Qwest, which sold its rural telephone business some year ago, is considering launching a service for the North West combining WiMAX BWA with satellite for TV and backhaul. If viable operators are seeing an economic reason to invest in such services, the need for subsidies is much reduced, except in extremely remote regions or hostile terrain, argues the anti-grants lobby.
WiMAX trials are not all about rural broadband however, and the technological challenges are at their greatest for operators building high speed wireless networks for dense urban environments where there are ‘massive obstructions’ to line of sight, such as skyscrapers.
One of the leading WiMAX proponents in this environment is Canadian last mile equipment maker Wi-Lan, whose proprietary but WiMAX-ready Libra 5800 product has been approved this week for use in the US 5.8GHz frequency band and is targeted at urban BWA providers.
Wi-Lan is an active supporter of WiMAX and will integrate the 802.16a standard at an early stage next year. It has contributed its implementation of OFDM (Wideband OFDM) to the physical layer of the 802.16a standard and its European cousin, ETSI HiperMan. Wi-Lan is the only supplier currently to use W-OFDM, which improves on basic OFDM by supporting greater speeds, correcting signal distortion and maximizing range.
Wi-Lan president and COO Sayed-Amr El-Hamamsy explained that Wi-Lan’s current technology differs from the 802.16a standard in that it uses a wider channel (10Mhz instead of 6Mhz) but it has been working with Fujitsu on 802.16a chips for delivery early next year and is then expected to migrate its products quickly to this platform. Libra 5800 delivers up to 32Mbps data rate in 10 MHz channels with a range up to 41 miles in a point-to-point line of sight configuration, or a radius of up to 22 miles in a point-to-multipoint line of sight system, which can achieve 192Mbps of aggregated data rate using six-sector cells. The move to WiMAX will improve non-line of sight capabilities, says El-Hamamsy – WiMAX gets its range by using more carriers (256) on narrower channels (6Mhz) and, like Libra, uses TDM for quality of service, allowing each station to have pre-determined data rates.
Also targeting the urban environment is Aperto Networks, another committed WiMAX supporter and Intel’s second 802.16 equipment partner, which is working with service provider MVS Comunicaciones to bring BWA to three Mexican cities – Mexico City, Guadalajara and Monterrey. MVS holds MMDS licenses for the 2.5-2.686GHz bands and will use Aperto’s PacketWave to deliver wireless access to businesses. “Mexico City has the highest density of population and greatest environmental challenges of any wireless market in the world," said Ernesto Vargas, president of MVS.
Aperto's base stations and subscriber units enable both licensed and unlicensed BWA at E1 speeds. Aperto Networks has been a pioneer in establishing the 802.16a standard and is committed to delivering systems for WiMAX certification. Its MAC is based on a TDMA implementation that is close to that recently ratified by the IEEE 802.16a Working Group, making migration to the standard relatively simple, the company claims.
One vendor that is contributing significantly to testing WiMAX in anger in the most urban of environments is Orthogon Systems, which specializes in BWA services that cope with massive obstructions. It is working with TowerStream, a local carrier which was the first operator to join the WiMAX Forum, to demonstrate a point-to-point service that leaps tall buildings in New York City, using Orthogon’s OS-Gemini wireless Ethernet bridge in unlicensed 5.8GHz band. This uses Multibeam Space Time Coding (STC) technology to transmit multiple signals around obstacles to reconnect at the receiving end, linking WiMAX or other BWA towers and expanding the reach of the metro area network. The technology is also being used in Chicago and is expected to be incorporated into WiMAX shortly.
For other equipment vendors, WiMAX and the new boom in BWA it could spawn represent a chance to resurrect their backbone technologies and take them into a new market, linking 802.16 towers to create wide area fixed or mobile networks. Increasingly, supporters of technologies that have traditionally been used for wired backbones are eyeing the potential of the expected explosion in metro area fixed wireless that will be sparked off by WiMAX. While 802.16 systems can be linked together in a mesh configuration to provide coverage for a wide area, there are still advantages in terms of capacity and power to using a carrier class backbone when building a really large or robust network.
Take free space optics (FSO), which vendor LightPointe is now presenting as a backhaul solution for Wi-Fi and, in future, WiMAX operators through a new deal with Terrawave. Or Resilient Packet Ring (RPR), the basis of the 802.17 standard, or Multiprotocol Label Switching (MPLS), both Ethernet backbone technologies that are targeted at telecoms carriers, but which now claim to decimate backbone costs for connecting WiMAX towers.
Free space optical technologies are mainly used to extend local fiber networks but can also be used for backhaul. They are laser-based and license free. One supplier specifically targeting this new direction and providing Wi-Fi and WiMAX backhaul is Omnilux. FSO is more expensive than wireless - $1,500 per node for Omnilux, which is cheap by FSO standards – but each node operates at 100Mbps and has routing and quality of service capabilities plus embedded Wi-Fi. Unlikely to be mainstream, but meshes of these nodes could also be an attractive option for some enterprises. In theory FSO meshes could be an alternative to WiMAX – NTT Data of Japan this week signed with Terabeam to deliver some BWA services using FSO – but the cost generally makes it prohibitive for mass market last mile services.
Now LightPointe has joined the fray in a partnership with Terrawave to provide Wi-Fi resellers with LightPointe’s 2.5Gbps bandwidth. Terrawave will incorporate its partner’s FlightSpectrum, FlightStrata and FlightApex products into its infrastructure range, which it sells to enterprises and hotspot builders.
"LightPointe's FSO products are an excellent addition to our portfolio because they address an important segment of bridging applications which require full-duplex, fast Ethernet connections and more," said Chris Marco, president of Terrawave. "These levels of throughput and connectivity are unattainable with traditional Wi-Fi or T1 lines.”
On the Ethernet side, supporters of MPLS and RPR say that their technologies can cut backhaul costs by 10 times or more while supporting VPNs, voice QoS and interactive video. RPR, in particular, delivers 100Mbps Ethernet to WiMAX or cellular towers.
This week, the industry body behind MPLS, the MPLS/Frame Relay Alliance, announced an implementation agreement that should make it easier for wireless carriers transmitting compressed voice traffic to migrate their backbones to IP/MPLS. This will be relevant for cellular operators and also for BWA companies.
One company that is active in promoting MPLS and is experimenting with combining that protocol with WiMAX and Wi-Fi is VeriLan. The company is currently testing a WiMAX mesh system for the Portland and coastal areas of Oregon which will have a reach of 100 square miles with MPLS backbone. President Steven Schroedl believes the combination of 802.16 or even 802.11 mesh networks with economically viable Ethernet backbones will provide a serious alternative to cellular and wired networks.
He said: “We are currently beta testing new 802.16 radios in Portland. The new radios will not require line of sight links, and will offer security with quality of service capability on a point-to-multipoint network. The new radios will be used where applications demand more performance and bandwidth.”
An autumn of tests and trials of such technological combinations will result in some clear real world performance figures for WiMAX by the end of the year, enabling operators to assess the scope of the protocol and the economics of implementing it in unfriendly environments, ready for the influx of low cost silicon on to the market in mid-2004. <<
- Eric - |
