Navini Networks, until recently one of the staunchest critics of the WiMax effort to create standardised wireless broadband, has made a sharp about-face and joined the WiMax Forum.

The networking equipment company, which has customers in over 25 countries, will become one of the first to offer a clearly-defined upgrade path from its own proprietary form of wireless broadband to WiMax. Good news for service providers and enterprises who want the inexpensive, standardised wireless broadband technology promised by WiMax backers such as Alcatel, Intel and Siemens.

Recent studies have shown that the adoption of proprietary systems such as Navini's is likely to delay the widespread adoption of WiMax, so prices will stay high and around the same as the existing systems. Nevertheless, Pyramid Research expects the WiMax industry to hit an annual turnover of $1 billion (£540m) by 2009.

Navini's current Ripwave products are based on a proprietary technology known as multi-carrier synchronous CDMA, and are designed with mobile wireless broadband in mind - essentially the same as the 802.16e standard on which the mobile form of WiMax will be based, Navini said. 802.16d, aimed at fixed connections, and 802.16e are both expected to be ratified later this year.

The upgrade path to WiMax will take two stages, Navini said. First software on its current Ripwave gear will be upgraded to allow partial compatibility with WiMax networks. Then, as of mid-2005, new equipment will be fully 802.16-compatible, Navini said.

The company had previously backed a rival standards group known as 802.20, which counts Flarion and ArrayComm among its other supporters. This standard has similar aims to 802.16e, but wouldn't be compatible with WiMax, making it more difficult to mass-manufacture equipment that would cover both wireless and fixed wireless broadband. Once 802.16e began to make significant progress, Navini believed it was time to jump ship from 802.20 to WiMax, the company said.

"It is our belief that standards are necessary to facilitate the healthy growth of this industry," said Navini president Alastair Westgarth in a statement.

Wireless broadband offers several major benefits over traditional leased lines or ADSL connections, including the ability to roam in connected areas and to use a single subscription for multiple locations, which would otherwise all need their own connection. Companies also have the option of setting up their own WiMax networks, eliminating dependence on a service provider.

"Just as wireless phones began replacing landline phones once performance became similar, we expect much greater demand for wireless broadband service now that speeds are comparable to DSL and cable broadband connections, with the additional benefit of access while on the go," said IDC programme director Scott Ellison.

Among Navini's recent customer signings is Irish Broadband, which last month said it would deploy Ripwave across Dublin. In the meantime, WiMax's proprietary competition is continuing to gain ground. US carrier Nextel earlier this week commercially launched a Flarion-based system in Reston, Virginia.

Last week service provider TowerStream attracted controversy by launching a Chicago service as "pre-WiMax", despite the fact that the equipment from Aperto and Alverion will not in fact be compatible with or upgradeable to WiMax. A Canadian consortium also began launching wireless broadband services in Vancouver and Ottowa last month, using 3G-based proprietary technology from NextNet.

The strong demand for such proprietary services shows that service providers will not necessarily wait for an unknown quantity such as WiMax, despite Intel-generated publicity, analysts said. At the moment, customers are attaching more importance to factors such as performance than to standardisation, they said.