WPAN as innovation?

Werner Almesberger werner at almesberger.net
Thu Apr 14 12:46:29 EDT 2011


Ron K. Jeffries wrote:
> ATBEN/ATUSB are not IMO "slow." that (cute)
> term makes better sense applied to the radio technology
> such as HopeRF that works in the lower freqiency
> bands such as 800/900 MHz and indeed have low
> throughput, maybe 50-100 Kbps while Werner's
> radios can deliver a megabit or better per second.

IEEE 802.15.4-2006 specifies a data rate of 250 kbps for the 2450 MHz
PHY, which is the PHY the AT86RF231 implements. (IEEE 802.15.4-2006
specifies a number of others PHYs, with characteristics less
interesting for our purposes, there are companion documents with
further PHYs, and they're still adding more.)

Atmel's AT86RF231 implements non-standard high data rates of 500
kbps, 1 Mbps, or even 2 Mbps, which trades receiver sensitivity for
speed. Each doubling of the data rate costs about 4 dB. (So if the
maximum distance is limited by signal strength alone, then 2 Mbps
would need 12 dB more than 250 kbps, which would reduce the range
to about 1/4.)

I measured that indoors range of 4-7 m with the standard data rate
of 250 kbps.

- Werner




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