Subject: [NEXTEL-1] 802.11s - IEEE Standard For Wireless Mesh Networks

From: NEXTEL-1
Date: Wed, 23 Jun 2004 15:23:46 -0400

June 22, 2004
802.11s - IEEE Standard For Wireless Mesh Networks
Esme Vos of MuniWireless.com wrote me recently: Don't you think mesh is
going to be commoditized, if it isn't already?

My reply:

Bottom line - done right, Mesh really, REALLY works- to the point where
you'd swear that it cannot possibly work, but it does. But it's not
cheap, it's not easy, and it's nothing resembling standardized. Dynamic
Wireless Mesh Networking is at the same stage as WLANs were in the early
90's; they work, but they're expensive and proprietary.
To become commoditized, the economic pressures have to drive the players
to a standards process like IEEE's. There doesn't seem to be that
pressure yet; those who really need what mesh can do need it badly
enough that they're willing to pay and put up with proprietary.

Oops...
Apparently pressure to standardize Mesh Wireless Local Area Networks
(MWLANs) is in fact being felt. In her Network World Wireless In The
Enterprise column this week, Joanie Wexler describes the formation of
IEEE 802.11s, which seeks to standardize Meshed Wireless Local Area
Networks (MWLANs).

Posted by Steve at 7:30 AM

Wexler translates the "standards-ese well: 802.11s aims to define a MAC
and PHY [layer] for meshed networks that improve coverage with no single
point of failure. In such networks, 802.11 cellular WLAN access points
relay information from one to another, hop by hop, in a router-like
fashion.

The IEEE 802.11s proposal document is a bit more verbose:

Scope of the Project. An IEEE 802.11 Extended Service Set (ESS) Mesh* is
a collection of APs interconnected with wireless links that enable
automatic topology learning and dynamic path configuration.

The proposed amendment shall be an extension to the IEEE 802.11 MAC. The
amendment will define an architecture and protocol for providing an IEEE
802.11 ESS Mesh using the IEEE 802.11 MAC to create an IEEE 802.11
Wireless Distribution System that supports both broadcast/multicast and
unicast delivery at the MAC layer using radio-aware metrics over
self-configuring multi-hop topologies. An ESS Mesh is functionally
equivalent to a wired ESS, with respect to the STAs relationship with
the BSS and ESS.

The amendment shall enable interoperable formation and operation of an
ESS Mesh, but shall be extensible to allow for alternative path
selection metrics and/or protocols based on application requirements. A
target configuration is up to 32 devices participating as AP forwarders
in the ESS Mesh. However, larger configurations may also be contemplated
by the standard. It is intended that the architecture defined by the
amendment shall allow an ESS Mesh to interface with higher layers and to
connect with other networks using higher layer protocols.

The amendment shall utilize IEEE 802.11i security mechanisms, or an
extension thereof, for the purpose of securing an ESS Mesh in which all
of the APs are controlled by a single logical administrative entity for
security. The amendment shall allow the use of one or more IEEE 802.11
radios on each AP in the ESS Mesh.

As Wexler notes in her article (and well documented at Mobile Mesh
Networking), there are now a number of incompatible MWLAN systems from
various vendors. Given the maturity and rapid evolution of 802.11, it's
no surprise that despite "mesh extensions" being included in the 802.16
standard (the basis of WiMAX), 802.11 will likely develop interoperable
Wireless Mesh systems first, and that Wireless Mesh will be a good fit
for, and go a long way in compensating for the "shorter range" nature of
802.11 used as Last Mile Broadband Wireless Internet Access.

The development of 802.11s serves to illustrate my point about why
802.16a/d/e/WiMAX won't necessarily and/or rapidly usurp other Last Mile
BWIA technologies such as modified Wi-Fi and proprietary systems. It's
not likely, but possible, that WiMAX will end up playing the role of
"IBM Token Ring" to the "Ethernet" of rapidly evolving 802.11 systems.
WiMAX will not enter a virgin BWIA marketplace; WiMAX will have to prove
itself as more cost-effective, more robust, seamlessly interoperable,
and generally better overall. That could likely happen... but it's far
from a given, especially when the competing technologies aren't
"standing still" such as the development of 802.11s.

More about Steve

Steve began his professional writing career with his column "Wireless
Data Developments" in Boardwatch Magazine, which ran from 1997-2001.
Since then Steve has authored other columns and numerous articles for
other magazines including Broadband Wireless Business Magazine and IEEE
Spectrum. In August, 2002, Steve was named to a panel that was convened
by the Federal Communications Commission in Washington D.C. to discuss
reform of the FCC outmoded spectrum allocation policies. Steve is based
in the Redmond, Washington area. More information about Steve is
available on his web page at www.stevestroh.com. Steve welcomes
feedback, questions, and comments via email - ?subject=Corante
BWIA"[email-masked].

About this Insider
Insight and analysis of significant developments in the rapidly-evolving
Broadband Wireless Internet Access industry.

http://www.corante.com/bwia/archives/004499.html

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