You win some, you lose some. Next-generation 802.11n WiFi offers very fast data rates, but these will be achieved only by hogging bandwidth in channels already congested with 802.11b and 802.11g links, industry experts say. Existing WiFi standards use 20 MHz channels, and users can double the data rate by doubling this bandwidth. Proprietary turbo modes on some 802.11g devices do just this by "bonding" two channels, something akin to using two lines instead of one on a crowded switchboard. There was criticism of this practice, so some vendors switched off turbo mode by default, or to have their gear switch the turbo mode off when it detects other WiFi networks. A late amendment to the 802.11n draft spec, however, specifically allows for optional 40 MHz channels, the equivalent of two existing ones.
Masato Kato, Buffalo engineering manager and observer at the 802.11n deliberations, said the amendment will leave only one non-overlapping channel at 2.4 GHz where several networks are already competing for airspace. Kato points out that channel bonding is illegal in Japan. Critics point out that 802.11n systems would be faster than existing WiFi even without channel bonding. Thus, real throughput could be 70-150 Mbps even before bonding, with higher rates still with it. Paul Senior, vice-president of Airspan, says that 802.11n can use the less congested 5 GHz bands and 2.4 GHz, and that speed is not the only advantage of the new spec over older ones. More robust security and provisions that will improve the standard of VoIP calls are attractive enough.
For more on 802.11n bandwidth hogging:
- see Clive Akass' Vnunet report
CLARIFICATION: Last week we wrote about an "802.11n Rush" involving companies such as Marvell, Broadcom, Netgear and Airgo. Broadcom's Henry Rael wrote us the following note:
Airgo Networks is the only chip vendor that has been marketing proprietary MIMO products. Broadcom did not introduce MIMO-enhanced chips before the draft 802.11n standard was announced. In fact, Broadcom was the first company to announce draft-compliant products after the EWC proposal was accepted by the IEEE. This is an important point for Broadcom, because the company has been very vocal about the need to honor industry standards. Broadcom, therefore, would like to avoid any suggestion that it was selling proprietary or non-standard based WiFi products. Release