I wrote: > With my ATBEN/ATUSB prototypes, I've obtained good to acceptable BER > for a distance between stations of 4-7 m indoors in a residential > area with relatively few interferences.
A clarification on the error rate (BER = Bit Error Rate, PER = Packet Error Rate): IEEE 802.15.4 defines a maximum PER of 1% for a PSDU of 20 bytes. This means that all bits of the PSDU, the length (1 byte) and the SFD (1 byte) be received without errors, and that enough bits of the preamble (4 bytes) must be received for the receiver to synchronize. To keep the numbers simple, let's assume that's 200 bytes in total. Thus 1-PER = 1-(1-BER)^200 With PER = 1%, we get a BER of about 50 ppm. Since our primary usage scenario, Internet access, would often use maximum-sized packets, I used max-sized packets for my measurements as well. The maximum PSDU size is 127 bytes. So we get 200+8*(127-20) = 1056 bits. Aiming for a PER of 1% with full-sized packets, the BER has to be lower, about 9.5 ppm. - Werner _______________________________________________ Qi Hardware Discussion List Mail to list (members only): [email protected] Subscribe or Unsubscribe: http://lists.en.qi-hardware.com/mailman/listinfo/discussion
