IP and smart antennas

smart antennas
There is no doubt that IP-based technologies cope with many of 3G’s limitations in terms of data transfer, and also provide a lower cost installation of local loop, which is not dependent on ‘line of sight’ transmission as most early solutions were. But they are still weak on voice – voice over IP has quality issues and requires specialized phones. In less than five years, though, we should have VoIP cellphones that will finally establish IP as the dominant technology for mobile broadband communications, sidelining the descendants of both 3G and 802.11x.

The cellular carriers are working towards this IP world with their own implementations, under the 4G label, but for the first time they will meet new and viable competition as they are forced to use a technology platform that can also be offered by smaller (and less debt-ridden) alternative operators. IP-based alternatives to 3G are coming from a host of mainly US start-ups, including Flarion, IPWireless, Soma and Navini, all using the OFDM (orthogonal frequency division multiplexing) physical layer technology at the heart of 802.11a and some digital television.

This splits a high frequency signal into several lower frequency ones, that are then sent by separate paths to achieve higher data rates than 3G. Many of these start-ups rely on smart antenna technology in place of conventional base stations, and could incorporate wireless Man standards as these develop. ArrayComm and IPWireless have been two of the stars of this American dominated field, but and two other promising start-ups are Navini Networks and BeamReach Networks.

Navini raised $25m in Series C funding earlier this year, bringing its total backing to date to $91m, impressive in the current investment climate – though a drop in the ocean if Navini fails to gain heavyweight partners for its ambitious smart antenna network plans. But given the new spotlight on last mile and on alternatives to 3G and fixed wire, the climate for start-ups such as Navini to gain powerful partners is improving greatly. Most carriers outside Europe, and some within it, are testing alternative last mile technologies and Nokia, Ericsson, Lucent and Nortel have all tested smart antenna networks using various approaches, although they have so far not pushed these aggressively to operators, presumably for fear of cannibalising their still lucrative business in selling conventional base stations.

Smart antennas are one of the most interesting approaches to restructuring the network in order to support more users at fast rates, offering broadband performance and quality over a wireless link. Smart antenna suppliers cut the number of base stations by using multiple antennas in parallel, making highly efficient use of the available spectrum. They can be implemented as a more efficient technology for 3G carriers, but can also operate as a separate network to challenge 3G.
Navini claims 70 percent lower TCO than first generation wireless broadband solutions and 50 percent lower than DSL. Its flagship product is the Ripwave base station and antenna system, which uses adaptive phased-array antenna technology that can penetrate walls. Ripwave modems connect to this network and offer broadband access to the internet and links between Wi-Fi and long distance networks.

Another broadband fixed wireless player, BeamReach Networks, completed a $15m series C round this year, claiming the money would enable it to ramp up for significant roll-outs in the coming year, following a current trial of its technology with US carrier Verizon in Virginia. BeamReach’s Airlink technology uses Adaptive MultiBeam OFDM, a smart antenna technology that claims 16 times better cell coverage than and better spectral efficiency than 3G. BeamReach says that, while 2G and 3G networks sometimes now include basic OFDM facilities, adaptive multibeam is more efficient because multiple frequencies can be reused in each cell, and data is transmitted over two channels at different frequencies to improve speed.

Adaptive OFDM gives spectral efficiency of over 10bits/sec/Hz/cell compared to
under 1bit for broadband CDMA networks such as W-CDMA. This contrasts with Navini’s approach, which is based on a technology called MCSB (multi-carrier synchronous beamforming), which is similar to BeamReach’s but based on time division rather than frequency division, which Navini claims is better for voice than frequency based solutions such as OFDM. Navini, an Intel-funded wireless broadband vendor, is looking to 802.20 as its key standard.

The start-ups will have to ensure that their efforts are standards-based and integrated with the WiMAX work to stand a chance of survival. And with WiMAX reducing the barriers to entry for new suppliers, they also need to establish a beach-head now to ensure that they have sufficient installed base either to survive in a newly competitive sector, or to be attractive to one of the larger players.