posted Mar 19, 2012, 2:30 AM by Andrea Vitaletti
We first discussed antennas and propagation. Most of the technologies discussed in the course will use LOS propagation. We discussed the free space loss formula and its main parameters, namely distance, frequency and gain. The presence of noise (in all its forms) generates errors. A "noise" channel, and in particular the effect of fading, can be modelled in several ways. For each of these models there is a relationships between the E_b/N_0 (SNR - Signal to Noise Ratio) and the  BER (Bit Error Rate). We then discussed several encoding techniques (D2A - encoding, A2A - modulation, A2D - sampling). We considered the trade-off between badnwidth efficency and BER as a function of the SNR (E_b/N_0). Apparently, digitalisation implies a waste of resources (see the "monkey" example), but it allow us to take advantage of the encoding techniques to deal with noise in a better way.