The raw, over-the-air data rate is 250 kbit/s per channel in the 2.4 GHz band, 40 kbit/s per channel in the 915 MHz band, and 20 kbit/s in the 868 MHz band. The actual data throughput will be less than the maximum specified bit rate due to the packet overhead and processing delays. For indoor applications at 2.4 GHz transmission distance is 10–20 m, depending on the construction materials, the number of walls to be penetrated and the output power permitted in that geographical location.[30] The output power of the radios is generally 0–20 dBm (1–100 mW).

Things are a little changed in spread spectrum communication. DSSS is using PN sequences to spread the symbols over pulses (or chips). Since there are 16 symbols, (16-ary modulation), with a chip rate of 1000 K chips per second, the symbol rate becomes 1000 K /16 = 62.5 K symbols/second. As there are 4 bits in each symbol, 62.5 K * 4 bits = 250 Kbps is the data rate that Zigbee allows for maximum.

With your formulation; Nyquist theorem is for noiseless communications and assumes the signal is sampled with 2 times the bandwidth for perfect construction. Note that it is the baseband bandwidth. It gives a theoretical upper bound.

Rana Hamza Shakil

Rana Hamza Shakil

And you can go through my publications and answers any time.