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I wouldn't say the idea of "The Man" tracking us has been put to bed. Who would've thought there'd be thousands of CCTV cameras deployed in London? They are/were expensive, fragile, and need lots of bandwidth. That didn't stop a gov't with a nearly unlimited budget and a penchant for snooping.

Tracking humans as they walk along a street with RFID tags in their clothes? Easy, since a single read from a 'registered' garment will suffice to ID the wearer. Extra reads are gravy. Garments are most often on the outside of the 'ugly bag of mostly water', so attenuation isn't a big deal. The distances involved are very short, and the gov't doesn't have to worry about stealth wrt reader placement. You know gov'ts are deploying RFID readers at borders to track cars by the now-required RFID tag in tires, right?

As for the ZigBee solution: I can't predict prices. ZigBee is in that precarious Ouroboros loop of "there-are-too-few-adopters-beacuse-it's-expensive-but-it-would-be-cheaper-if-there-were-more-adopters". That sort of thought pattern is what blew Norman's circuit breaker.

If you're going for a full-on product, then yes, you'll need those things. If you're hacking together something, then quite literally a few soldered on wires and either a thermistor or solid state temp sensor would do. We're talking an extra $2 or so.

Alternatively you could go with a different chipset. There are 'naked' ZigBee chips out there if development costs are less important than unit cost. You can get the chipset used in the digi modules; also Microchip has a few solutions, but you'll pay dearly to license the ZigBee stack, and be doing some serious low-level hacking.

Another solution if you don't require actual ZigBee interoperability: go with straight 802.15.4 and a simpler, cheaper protocol on top of it. There's MIWI, digimesh, plus a whole host of others.

Good luck with your project - you seem quite passionate about it.

Sounds like open standard *Zigbee* http://zigbee.org/ networks. Been hearing about Ember http://ember.com/ chipsets and self-healing, self-discovery wireless mesh networks for a few years now. Pretty quiet as of late.

It is important to understand that IEEE 802.15.4 is a MAC layer spec, and not a routing protocol. As such, 802.15.4 is not zigbee the same as Ethernet is not TCP/IP. The marketing people at the zigbee alliance have done a good job of saying everything 802.15.4 is "zigbee compatible" which I think is a bit misleading if not disingenuous.

Note that the MaxStream press release says this in that the radio is only "zigbee ready" and will be upgradeable (firmware?) to the zigbee routing protocol at some point in the future.

This is not to say that the MaxStream radio isn't any good. I have used MaxStream products in the past and they are quite reliable.

The example about Ethernet != TCP/IP is particular interesting. The father of Ethernet, Bob Metcalf, is on the board of directors for Ember. Ember is the driving force behind Zigbee.

Wireless sensor networks are not new; there is even a textbook published recently on them (Wireless Sensor Networks: Architectures and Protocols). Many corporations have active WSN programs, including:

Motorola

Ember and

Figure 8 Wireless.

University research programs, in addition to Berkeley, include:

UCLA WINS

MIT uAMPS

plus those sposored by DARPA.

The IEEE 802.15.4 standard, available here, was designed to support such networks. The ZigBee Alliance, an industrial consortium of over 60 companies, is the marketing and compliance arm of the 802.15.4 standard, as the Wi-Fi Alliance is to 802.11. The vitality of the ZigBee Alliance, which had over 350 attendees at its recent open house in Silicon Valley, is an indication that this technology is moving from research into commercialization; the commercialization of wireless sensor networks is the real significance of the Wired article.

This strikes me more as being like mesh networking instead. The way they establish their own network by routing amongst themselves is a key characteristic of mesh technology. What I have to wonder is this: how far along will this concept go? Could it be that these are the predecessors of a landmine problem of the information age?

According to the article it seems that their only real selling feature is to increase the robustness of a cell network without having to add additional towers. There might be other reasons to have P2P enabled phones but this one is just plain silly.

First, this would only really work in well-populated areas with high densities of regular cell phone users. But these cities are already very likely to have a strong saturation of cell coverage, and it is probably relatively economical to install new network towers in such high density areas.

Second, if an emergency occured, a la 911, where the load is exceptionally high, I can't imagine this system of low powered devices holding up anywhere near as well as a decently saturated network of towers (that also have a lot more power). The decentralized network might be theoretically more robust, but not if everybody's trying to make a call at the same time and not when the device range only allows for a very limited number of localized connections to form.

Wireless P2P and multi-hop) systems are really cool, but it's not going work for everything or solve every problem. One day they may become ubiquitous, but are likely to be first employed for niche applications only. Cell phone applications and benefits will probably be limited to local network communications.

Maybe such a system could one day be used to help improve coverage deep within buildings, or for very localized load balancing, but I doubt that they will or should be trusted technically as an alternative to building an independently robust network of towers etc. And, if they are only proposing the technology as an adjunct for increased reliability, then I just don't see a very strong business case.

There are many other research programs, both academic and industrial, on wireless ad hoc networks, going back at least to the 1978 DARPA-sponsored Distributed Sensor Nets Workshop at Carnegie-Mellon University. Most of the work has been funded by DARPA, by the low-power wireless integrated microsensors (LWIM) project of the mid-1990s and now by the SensIT project. (Their projects page lists more than 25 academic research programs on these networks, complete with links.)

The University of California at Los Angeles, often working in collaboration with the Rockwell Science Center, has had a Wireless Integrated Network Sensors (WINS) project since 1993. UCLA also supports the similar-but-different "Smart Dust" program, which also employs ultra-low-power networking, but uses optical communication between network nodes.

Professor Anantha Chandrakasan at the Massachusetts Institute of Technology is the Principal Investigator of the uAMPS (microAMPS) project.

On the commercial side, these networks are being developed by Ember, graviton, Wherenet, and Motorola, just to name a few.

The ZigBee industry consortium is the marketing and compliance arm of the IEEE 802.15.4 draft standard, in a relationship similar to that between WECA (with the "Wi-Fi" brand) and IEEE 802.11b. This draft standard for ultra-low-power, ultra-low-cost wireless networking, now under development, should be finished this winter.