Hi pancho_hideboo,
Quote:How do you define S/N for receiving signal under multipath fading ?
that's really what I'm trying to understand actually.
I was looking up a bit about Rayleigh multipath channel model, and apparently the channel can be modeled as a vector addition of two signals with different attenuation, phase shift, and time shift. So ignoring the time shift for now, the actual power which we receive is ultimately attenuated due to the possible phase difference of the two signals (in the Rayleigh model). My understanding is that the SNR does not include the effect of this attenuation. Therefore, when comparing the Rayleigh model to the AWGN model, a higher SNR is required for the same BER.
Am I on the right track?
BTW the main reason I'm asking is I'm trying to figure out the SNR requirement for the IEEE 802.15.4 standard. Several papers have quoted an SNR requirement of about 0 dB, but I don't think they took multipath fading into account. The IEEE 802.15.4 standard says the SNR required is about 5-6 dB while one or two papers which study the effect of multipath fading for the 802.15.4 standard show that the required SNR is much higher (around 14 dB). So are they all talking about the same definition of SNR? I'm inclined to believe that works which include multipath fading...
thanks,
Aaron