Two weeks ago at the Cellular Telecommunications & Internet Association's Wireless 2005 trade show, LG Electronics, in announcing a partnership with Nortel Networks that focused on 802.16 WiMAX solutions, also noted it was becoming more involved with other IEEE standards groups, specifically citing the 802.21 working group as an example.

In a world in which 3G mobile, Wi-Fi and — potentially, at least — WiMAX technologies are rapidly converging, name-checking 802.21 could become a popular practice in the coming months. The working group, chaired by Ajay Rajkumar from Lucent Technologies, is developing standards for media-independent handover services, the interface protocols between heterogeneous network types. This includes interfacing between 802 networks, such as Wi-Fi, WiMAX and personal area network (PAN) technologies but also between 802 networks and non-802 networks, such as cellular and wireline.

“This is one of the growth areas of convergence,” said Jeff Orr, senior product marketing manager for Proxim. “As you move from an 802.x network to an 802.y network or a cellular network, what types of hand-off controls are you going to need?”

At this point, 802.21 may not be as well-known as the 802 standards programs, including 802.11 for Wi-Fi, 802.15 for short-range wireless data, 802.16 for WiMAX, 802.20 for PANs and 802.3 for wireline Ethernet access networks. Also, several proprietary solutions from companies such as PCTEL and NetMotion Wireless have begun to fill a growing need for inter-network roaming solutions. But, an 802.21 standard arguably will elevate all of these standards by helping them co-exist in the same environment in a way that is palatable to users.

“The 802.21 effort really came about from the idea that as a user is faced with multiple potential interfaces available, a real-time application like voice over IP doesn't have an intelligent hand-off capability,” Rajkumar said. “An information services element could provide information on which network interfaces are available and then prioritize and decide based on different factors which is the best interface to use.”

He added, “The goal from a user perspective is to maintain session connectivity between different environments.”

The 802.21 working group began its effort one year ago this month, after the IEEE executive committee of chairpeople from other working groups studied the hand-off issue for several months and decided there was enough need to pursue the new standard. Rajkumar, who has been interested in inter-networking protocols and wrote a white paper on the subject for Bell Labs, said membership includes more than 50 companies, including the largest vendors of end-to-end network infrastructure, device companies, chipset developers and even service providers.

“Some of the service providers are very intently listening and tracking what's going on,” he said. “Others are taking a more proactive role during the requirements phase by suggesting how quickly handovers should be made.”

At Wireless 2005, an official for one wireless carrier told Telephony his company is “keenly interested” in the development of 802.21 but doesn't want to publicize its interest in “something that's still getting drawn up.”

Rajkumar said the 802.21 working group has received several proposals for the standard, and group members are actively debating how to harmonize these proposals into a single specification. The group plans to make its initial down selection vote toward a first-draft standard at its next meeting in May.

802.21: A work in progress

2003 — IEEE working group chairpeople discuss need for standard support “media-independent handover services.”

March 2004 — 802.21 working group launches to address potential standards for MIHS.

September 2004 — Call for proposals for the new standard. Initial work items defined.

November 2004 — Proposals received by 802.21 group. Submissions closed.

January — Debate and discussion regarding submitted proposals and how to reach compromise.

May — 802.21 working group plans first down selection vote in attempt to agree on first-draft standard.