ZigBee: provider of wireless solutions

[woody28]

channel filtering zigbee

Next Home and industrial automation solution.

I think it is best if they provide it with good price on one chip design .

www.zigbee.org

 

[flatulent]

two problems

This idea has two technical problems. Bluetooth has a range shorter than customers want. This system is even shorter. Bluetooth has frequency hopping which is cheaper to impelent that direct spread. This system is direct spread.

It looks like this system is a replacement for the IR system and will be good in that application because it is less directional. It will cost more than the IR and the Bluetooth nodes.

 

[rfsystem]

Sorry,

ZigBee is using the LowRate mode to increase the range. That is only possible by using lower channnel bandwidth in BT or using a correlator after channel filtering.

So the most easier way to be adaptive is choosen.

The biggest issue is to being in synchronism with the beacons and have a power consumption less than a 32kHz crystal in average. The second one is to minimize the protocol stack code size that a lower power microcontroller could run this.

Zigbee should address this.

 

[flatulent]

multipath problems

The link above shows a burst symbol rate of 64 ks/s with 4 bits/symbol and 11 chips/symbol. I suspect that the low chip rate will not overcome multipath problems even if the data rate is cut back to allow 1 bit per symbol. With the nodes fixed in space in a home automation network with multiple parallel walls some will not work.

I do not think that consumers will be inclined to experiment with arranging the movable nodes to make the system work.

 

[rfsystem]

Indeed,

the multipatch immunity is independ of the coding gain. It is only to increase the range.

The chiprate is well below the fading bandwidth. For higher bitrates you require OFDM, long training, of chirp processing.

 

[Spartacus]

I don't want to be negative here but having first hand experience with evolution of Bluetooth I think Zigbee would have a very tough time trying to get anywhere.

 

[flatulent]

my 802.11 expreience

It looks like the zigbee is a scaled down version of 802.11. My experience with the original 802.11 version which had data rates from 2-8 times the zigbee (which were negotiated as part of the protocol) and had hardware filters for each data rate is dismal. A node was put at the end of a hallway in an office environment. Down the hallway were offices on both sides. We had to put a 10 Dbi antenna on the node and 6 dBi antennas which were custom positioned for multipath rejection in some of the offices to get a 20 m range that worked properly.

I think that general consumers will not put up with this sort of complexity and need of engineering judgement for using this network in their homes.

 

[visualart]

ZigBee

atmel and the firgure 8 can provide the zigbee products.