The Last Mile: WiMAX and Broadband

Wireless Alternatives
Various technologies are being trialled for delivering broadband wirelessly to the last mile:
  • to extend the edges of the 3G network and fill in coverage gaps
  • to provide a lower cost alternative to cable and DSL
  • to provide enterprise campus-wide or multi-site wireless networks by providing backhaul for WLANs.
The key technological approaches are:
  • WiMAX
  • Wireless Local Loop based on IP and OFDM, including wireless voice over IP
  • Satellite
  • Smart antenna

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. Hence the excitement around Wi-Fi hotspots, hotzones and community networks, but coverage scalability beyond a few nodes is hard to achieve without performance failures.

Enter WiMAX, promising a lower cost backhaul for these hotspots than T1 and the option of a mesh network topology, as well as being a wireless extension to cable, fibre and DSL for last mile. WiMAX will drive broadband wireless access (BWA), but it has also come to the fore at a time of renewed interest in wireless last mile, as operators look for new sources of revenue and consumer demand for fast internet access grows exponentially.

Like Wi-Fi, BWA looks set to achieve the difficult task of creating a boom in a depressed communications sector, by offering better price/performance for network users and a revenue opportunity for squeezed suppliers. Europe has been slow to get excited about this market, but now that BWA solutions based on IP are becoming realistic, even the 3G operators there will need to examine these as an addition to their service.

In the US, last mile and wireless broadband solutions using unlicensed spectrum have been given a huge boost by the freeing up of vast swathes of bands by the FCC. The US carriers have also shown interest in last mile solutions to extend their networks and plug gaps. In Europe, progress is slower because the carriers have a more ubiquitous network and a vast financial investment in conventional cellular networks, and regulators have been less forward thinking.

Licensed wireless technologies ArrayComm, Flarion Technologies, IP Wireless and other vendors, many using smart antenna approaches, are the most viable wide area wireless solutions available to operators and WISPs now though most customers will be looking to those with a clear 802.16 roadmap. Designed from the ground up to support metropolitan area services, they'll leverage the existing cell tower infrastructure to deliver data services at prices far below those of 3G, reliably and with coverage far better than that of Wi-Fi. With WiMAX, they will have a broader market to address, with low cost operators working in unlicensed spectrum.

Cellular carriers cannot be ignored – their assets of licensed spectrum and vast cellular tower infrastructure will be essential to ensure the survival of any new alternative. New wireless broadband technologies may cut into cellular networks’ business, but they will never be an either/or – cellular operators need last mile solutions to extend their systems and subscriber bases at an economical rate, while the last mile pioneers will stand a better chance of survival if they integrate with and make use of the support and infrastructure of the operators if their technologies are not to be confined to niches. They will be able to use 802.16a base stations as alternatives, but these two systems are likely to interoperate as they evolve, especially with giants like Nokia straddling both camps.

Nearly all the proprietary point/multipoint BWA vendors are doing the sensible thing and refocusing to build their products around WiMAX silicon, ensuring lower costs of manufacture and interoperability. Quickest off the mark are those that use 256 sub-carrier OFDM, which is emerging as the winner among the PHY variants.