Slashdot Mirror

For those whom are not aware of this technology, I gladly provide the following linkage:

-- Article @ Network World Fusion

-- Article @ Comms Design

-- Published Standards & Drafts

Enjoy! :-)

I attended a talk today by Roger B. Marks, a member of the IEEE 802.16 standards committee where he described the standard in detail. Many people say just add a pringles can to 802.11 to extend the range, but there are many other issues beyond range. 802.11 and 802.16 are designed for different purposes.

Among other things, Mr. Marks described that 802.11's MAC uses CSMA/CA (carrier sense multiple access with collision avoidance). The carrier sense means that it listens (or tries to listen) for other devices broadcasting and only sends when it detects silence since the receiver can only handle one transmission at a time. This is fine for wireless LAN's where for the most part, all of the devices can "hear" each others transmissions and figure out when its ok to send. In an 802.16 MAN (metropolitan area network), the users' devices can't receive each others transmissions so the base station assigns each device a time slot in which to send & receive its data. (For more information on IEEE802.16, see their website: http://WirelessMAN.org.)

It appears that almost the entire /. crowd today has not even a glimmer of a clue as to what 802.16 is all about sooooo .... 10101 ~ -< ))) "802.16" ((( >- ~ 10101.

On the IEEE page there is a good overview document (zipped PDF).

It covers the basics, such as:
Bandwidth: Up to 134Mbps
Hub Radius: A few kilometers
Line of sight propogation

¥ Compared to a Wireless LAN:
--Multimedia QoS, not only contention-based
--Many more users Many more users
--Much higher data rates Much higher data rates
--Much longer Much longer distances

802.16 MAC: Overview
¥ Point-to-Multipoint Point-to-Multipoint
¥ Metropolitan Area Network Metropolitan Area Network
¥ Connection-oriented Connection-oriented
¥ Supports difficult user environments Supports difficult user environments
--High bandwidth, hundreds of users per channel
--Continuous and burst traffic
--Very efficient use of spectrum
¥ Protocol-Independent core (ATM, IP, Ethernet, ) ¥ Balances between stability of Balances between stability of contentionless contentionless and
efficiency of contention-based operation
¥ Flexible QoS offerings Flexible QoS offerings
--CBR, CBR, rt rt-VBR, -VBR, nrt nrt-VBR, BE, with granularity within classes
¥ Supports multiple 802.16

On the IEEE page there is a good overview document (zipped PDF).

It covers the basics, such as:
Bandwidth: Up to 134Mbps
Hub Radius: A few kilometers
Line of sight propogation

¥ Compared to a Wireless LAN:
--Multimedia QoS, not only contention-based
--Many more users Many more users
--Much higher data rates Much higher data rates
--Much longer Much longer distances

802.16 MAC: Overview
¥ Point-to-Multipoint Point-to-Multipoint
¥ Metropolitan Area Network Metropolitan Area Network
¥ Connection-oriented Connection-oriented
¥ Supports difficult user environments Supports difficult user environments
--High bandwidth, hundreds of users per channel
--Continuous and burst traffic
--Very efficient use of spectrum
¥ Protocol-Independent core (ATM, IP, Ethernet, ) ¥ Balances between stability of Balances between stability of contentionless contentionless and
efficiency of contention-based operation
¥ Flexible QoS offerings Flexible QoS offerings
--CBR, CBR, rt rt-VBR, -VBR, nrt nrt-VBR, BE, with granularity within classes
¥ Supports multiple 802.16

This PDF indicates data reates between 6-54 Mbps. Apparently 27 might be the goal to start with, if I'm reading the figures right (Halfway on page 2).

That's an excellent idea. Its difficult to implement that in practice because government isn't fluid enough to keep up w/ the technology, though it is trying to, particularly in the case of 802.16.

Spoken like someone who has never tried to set up 802.11b in a populated area.

Actually, I have :)

We aren't talking about you and your neghbor using cordless phones on the same frequencies anymore. We've gone Waaaay beyond that.

Yes, I wasn't suggesting that either the technology or the regulatory regime that 802.11b exists in is up to the task of replacing say the cell phone network. Neither was the author of the article on CNET. 802.11b does establish a model for what is possible if you have an open standard and a regulatory environment that supports its.

Are you familiar w/ the work of the 802.16 working group? They are seeking to implement technology and standards in cooperation w/ government to make ad hoc wireless metro area networks more feasible. 802.11b was not designed for that task and ultimately will not be able to scale for it, but the model is what's important.

Hi, I appreciate the thought that went into your comment but I thinked you've assumed unlicensed == unregulated which is not true. Equipment in the 2.4 ISM band is regulated, devices have strict power restrictions and behavior ettiquette that they must follow, backed by the force of law. If the regulations are not sufficient for a target application then government needs to come up with regulatory regimes that are in partnership with industry. And that's exactly what's happening.

License free (open, if you will) 900mhz and 2.4ghz are a different model of spectrum regulation resulting from equipment manufacturers (particularly apple in the 802.11b case), rather than content providers, taking the lead in working with government to work out the regs and in the standards bodies. The new NII band in 5ghz is a refinement of this process, a new partnership of government and industry centered around open standards. Heck a member of NIST's NWEST group is the chair of the 802.16 working group. The kinds of partnerships that are taking place are very much like those that the open source community are looking for in advancing its movement, as Benkler's writings will bear out.

I'd be interested to hear what you thought of the technical papers that I reference, or the work of the 802.16 working group to hear if they address any of your concerns.

The IEEE is working on a new set of standards that specifically address so-called Metropolitan Area Networks. They're talking about using an unlicensed band in the UNII 5-6Ghz range. You can read about it at WirelessMAN