Broadcom jumping the gun with pre-standard 802.11n?
If history is anything to go by...
Broadcom looks set to release pre-standard silicon based on the emerging 802.11n fast Wi-Fi standard, aiming to repeat its successful gamble on early release of 802.11g products last year. Meanwhile, GlobespanVirata (GSV) is the latest Wi-Fi chipmaker to pre-empt 802.11n by releasing ‘standards-plus’ products that turbocharge 54Mbps 802.11g to achieve higher data rates.
Atheros already does this with its 100Mbps Super G technology as does Broadcom itself, though Intel steadfastly refuses to go off standard and has criticized such solutions for limiting interoperability and fragmenting the market. Now GSV – soon to be part of Conexant – has achieved theoretical speeds even higher than those of ‘n’ through its Intersil unit’s Prism Nitro platform, which can now reach 140Mbps – although in the real world, performance will be closer to 70Mbps.
Although widely criticized for releasing 802.11g chips before the standard was fully ratified – raising risks for early adopters that their kit would be incompatible with the final specifications – Broadcom reaped the rewards in the consumer market, which proved eager to adopt even pre-standard ‘g’. Its early move enabled it to steal a significant march on rivals such as Atheros, which was more focused on the other 54Mbps Wi-Fi variant, 802.11a, and Intel, which has made a policy of waiting for full standards in the WLAN market.
Now Broadcom seems intent on repeating its success in 802.11n, the 108Mbps version of the standard, which is unlikely to be ratified until late 2005 at the earliest. Company officials have said that they will sample chips based on drafts of ‘n’ later this year, which could point to product release about a year ahead of ratification.
The company appeared to step back from this position after Stuart Kerry, chair of the IEEE 802.11 working group, wrote in a pre-Christmas letter to group members that “it is improper to claim compliance with a standard or any amendment that has not yet been approved”.
Broadcom responded this week with official statements saying it had “no plans to preemptively launch products that could possibly undermine the strong standards-based industry that we've helped build”. But this was a little late, given that Thomas Lagatta, group vice president of the chipmaker’s enterprise computing division, had already told US journalists that: “We're not going to slow down for the standard”.
The situation is different in several ways from the ‘g’ dilemma of early 2003. The standard is further out – pre-standard ‘g’ silicon anticipated the final specification by only a few months – and so the risk to early adopters could be higher. This will undoubtedly deter the enterprise market, which is only just moving to 54Mbps Wi-Fi, held back by, among other factors, nervousness about incompatible kit. Cisco, Broadcom’s key customer, said its enterprise customers are asking about 802.11n but not yet demanding it.
However, in the consumer market standards are less important and there seems to be a limitless demand for increased speed, especially in the US. Vendors underestimated this in the shift to 54Mbps, assuming that users would be happy with 11Mbps 802.11b for a year or more to come, and they are determined not to make the same mistake again. This has seen companies already releasing proprietary products that achieve ‘n’ levels of performance – up to 108Mbps.
Broadcom and TI have both taken this route, but notable among the fast Wi-Fi chip vendors has been Atheros, which missed the 802.11g boat in the early days, but has been the most aggressive in launching turbocharged or ‘standards-plus’ 802.11g chips. In November, Broadcom engaged in a war of words with Atheros, claiming that the latter’s Super G technology – used by D-Link and Netgear, among others - degrades the performance of neighbouring Wi-Fi links (something Atheros denies).
Now these players are joined by GSV. Its Prism Nitro XM Xtreme Multimedia is an upgrade for its 802.11g, 802.11a and 802.11a/g chips, used by Netgear, D-Link and SMC. With these vendors increasingly targeting the home Wi-Fi market, for applications such as wireless video streaming around the house, the pressure is on to maximize data rates.
The key to the new speed is a technology called DirectLink, which automatically creates a link between clients – or from a client to a media source – without going through the access point. The client will still use the AP’s security features, but data will not pass through the AP, instead using a ‘side session’, which doubles the data rate of the Nitro chipsets. Performance is further enhanced through the use of more commonplace packet bursting and file compression techniques. Compressed audio and video will be transmitted at the highest rate, but content such as encrypted data will not.
GSV claims that networks based on its new chips remain compatible with standard ‘g’ and ‘a’ clients – operating at their normal speeds - and do not interfere with other WLANs, the two main criticisms levelled at ‘standards-plus’. Interference is avoided, the company says, by adopting a single-channel solution. Nitro MX operates in just one Wi-Fi channel so that it does not collide with networks using adjacent channels. The 2.4GHz band used by 802.11g has 11 channels in the US, but only three are non-overlapping.
Turbo products like Nitro MX are putting pressure on the IEEE to accelerate development of 802.11n and making it more critical for Broadcom to create pre-standard products. The success of products based on Super G show that there is already a market for 108Mbps Wi-Fi and, having slipped behind Atheros in souped-up 802.11g, the logical way to bite back is
to support ‘n’, which even in a pre-standard form will have greater claims to interoperability than proprietary implementations of ‘g’.
The 802.11n specification is currently at the project authorization phase. Key to its appeal is that it promises to deliver real world rates far closer to its theoretical maximum than current Wi-Fi variants, by addressing throughput at the MAC layer rather than as a signalling bit rate in the physical layer modulation scheme. It will operate in the 5GHz range along with 802.11a and so will have some of the same compatibility problems that exist between ‘a’ and 2.4GHz ‘b’ or ‘g’ radios.
"WLANs having throughputs of 100 Mbps were considered impossible just a few years ago," said the IEEE’s Kerry. "But the success of IEEE 802.11 WLANs and a number of technology improvements have made far greater throughput feasible. These improvements include higher performing radio frequency and analog chips based on advanced CMOS technology and the integration of entire WLan adapters onto a single chip."
The IEEE will also investigate the use of smart antenna technologies to increase the range of 802.11n and future 802.11x standards, and is looking forward to a next generation after ‘n’ that will deliver up to 320Mbps by 2007.
© Copyright 2004 Wireless Watch
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