WiMAX approaches tipping point with new specs and carrier support
Potential for interference
The third quarter looks set to be the turning point for WiMAX, seeing the release of a new version of the standard that will significantly boost silicon roll-out. Carrier interest, critical to success, is rising and British Telecom is the latest major telco to say that it will carry out trials, following in the footsteps of AT&T and Nextel. But significant spectrum and interference issues need to be addressed if WiMAX is to reach its full potential.
With two major events focused on the standard running last week, an increasing number of equipment companies, including Siemens Mobile, were also laying down roadmaps. Siemens will work with Intel on base stations and on future mobile devices incorporating Wi-MAX. Intel, as usual, dominated the agenda at both meetings – the WiMAX Forum’s own summit and the WCA Annual Symposium, both in San Jose. Broadband wireless will bring the next five billion users to the #Internet, said Sean Maloney, the high profile general manager of Intel’s Communications Group and WiMAX’ chief ambassador. The cost effectiveness of 802.16 means that "WiMAX-certified systems will provide the building blocks truly to usher in the broadband wireless revolution."
"We see a three-phased deployment of 802.16 technology that will begin with fixed outdoor antenna installations, quickly bringing wireless to emerging markets and speeding the installation of broadband services without the need to lay wire or cable," said Maloney. "The technology will then rapidly progress to indoor antenna installations, broadening its appeal to carriers seeking simplified installation at user sites. Finally, in the third phase, WiMAX certified hardware will be available in portable solutions for users who want to roam within or between service areas."
At this stage, Intel will have WiMAX Centrino-style chipsets for handsets that connect directly to the antenna, but for the coming 18 months it will focus its marketing activities on infrastructure rather than client systems – though increasingly, its R&D will be working on the WiMAX portable.
Chip and equipment makers are starting to roll out ‘pre-WiMAX’ gear that is ready to migrate to the standard, as well as hardware based on the first iteration, 802.16a. However, the real turning point will come with the finalization of 802.16d, a revision to ‘a’ that brings together the original line of sight 802.16 standard, its non-line of sight successor 802.16a, and the 802,16b and 802.16c extensions for quality of service, testing and interoperability. This specification is more advanced than ‘a’, especially because it allows for smaller, cheaper power amplifiers, bringing down the cost of implementation, and because it supports smart antenna schemes such as Multiple In Multiple Out (MIMO), which held maximize real world range and power.
The new variant is now solid enough for first chips to be designed in time for third quarter roll-out. The revision was finished at the IEEE meeting in Vancouver, Canada last week and a test suite will be ready in September.
Wavesat and Atmel are already working on 802.16d silicon and UK-based Airspan Networks says it aims to be the first to ship fixed wireless systems based on ‘d’. Its kit will be based on Intel’s upcoming Rosedale WiMAX chipset and Intel is also working with Alvarion, Aperto and Redline. Fujitsu has also begun development of an 802.16d baseband in conjunction with Wi-Lan and two Taiwanese chipmakers are expected to bring out early WiMAX devices.
Mohammad Shakouri, VP of business development at Alvarion, says the critical next step is to get the certification process up and running. This is essential to win operator trust after various high profile broadband wireless failures of the past, such as Teligent, put many companies off this sector. He points out that companies are now shipping products that are compliant with 802.16a – although he agrees that ‘d’ adds significantly to the attraction of the standard – but they are not yet officially certified as such, and so will be treated with caution by possible telco customers, who would otherwise find the low costs of WiMAX ($100-$150 per home for residential services, and $5,000 to $30,000 per base station, Alvarion says) attractive.
Although there is still considerable operator suspicion to allay, more and more carriers are assessing WiMAX as an alternative or parallel to wired or cellular networks. Three operators, AT&T, Covad and PCCW, joined the WiMAX Forum last week and more are expected to follow shortly. BT and UK Broadband in the UK, Iberbanda in Spain, MVS Net of Mexico, Brazil’s Neotec and Reliance Infocomm in India are all planning or “serious considering” WiMAX trials, according to Intel, which takes a strong role itself in evangelizing Wi-MAX to operators and governments worldwide. BT is one of the largest telcos so far to take a public interest in WiMAX and is expected to roll out trials in rural areas in the near future.
The WiMAX Forum admits that most of its work in 2003 was focused on chips and equipment and that there was very little input from carriers. It aims to rectify this with the formation of its Service Provider Working Group, to encourage contributions from the carrier community and to influence spectrum regulators. This should make it easier for operators to influence the development of the WiMAX system profiles, a process from which they have complained of being excluded in the past, presumably one factor in their slowness to become actively involved until this month. Most importantly, the new group will develop and promote the business case for service providers to deploy 802.16; will focus on real world multimedia applications; and will create standard network management interfaces.
The aim is to gain greater carrier input at an early stage in order to shorten the trial and review process and reduce time to market. To improve carrier confidence, it is essential for WiMAX to work with all the major radio standards and their governing bodies. Action to prevent collision with other wireless technologies and to ensure that WiMAX can be rolled out consistently in different countries is becoming urgent as products approach the market. This is the remit of the WiMAX Forum’s Regulatory Taskforce, which also exists to lobby for allocation of spectrum for WiMAX applications on a country by country basis. One key task is to ensure interworking where WiMAX shares spectrum with other protocols, such as Wi-Fi at 5GHz and 3G in the MMDS spectrum (2.5-2.7GHz).
For all the official line that WiMAX and Wi-Fi are complementary, unless their two bodies work closely together, there is potential for interference in the 5GHz band where 802.11a operates – especially for outdoor Wi-Fi products, which tend to work higher up the band than indoor ones, and therefore closer to WiMAX. Guidelines are essential to prevent chaos from “serious contention”, says Paul Senior of Airspan, and head of the Regulatory Task Force, especially as both technologies develop. For instance, 802.16 transmits control data every 2.5ms, blocking other users from its channel, and the Wi-Fi QoS extension, 802.11e, has a similar functionality, making it behave more like WiMAX. This will be the first priority of the Task Force, working with the Wi-Fi Alliance and IEEE.
More ambitious is the need to work with regulatory bodies to try to obtain the “best deal” for WiMAX operators- for instance, lobbying countries where 802.16 frequencies are reserved for other uses.
One obstacle is that WiMAX has both fixed and mobile aspects, but these tend to be handled separately by regulatory bodies, with mobile technologies limited to specific bands. For instance, some countries treat 3.5GHz as fixed only, which could be a major restriction on 802.16e, and an issue that needs to be sorted out before that version of the standard appears in products in about 18 months’ time. And others allocate 3.5GHz only for satellite, although this can share happily with broadband, as it does in the UK.
There are also limitations on usage of the 5.8GHz band, particularly in Europe, that could constrain the range and capacity – and so the appeal – of WiMAX if negotiations with the region’s regulators are not successful.
In summary, like most wireless bodies, the WiMAX Forum Task Force is pushing for consistency of spectrum allocation across different regions and for cooperation among standards groups to minimize the risk of interference as frequencies become increasingly crowded. Such work will be as important as the technical developments of the vendors to convince the operators to ramp up their trials in the coming months and so create the expected boom in WiMAX-based services at the turn of the year.
© Copyright 2004 Wireless Watch
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