ECTE465 / ECTE965 - Wireless Communications

Tutorial for Week 5s lecture

August 23, 2007

1. For the orthogonal chip sequences v1 = {+1,1,+1,1} and v2 = {+1,1,1,+1},apply CDMA modulation to the data bit sequence 01101 to generate the encode sequences1 and 11111 to generate s2.

(a) Show that if these sequences are added together with with the weights

s = s1 3s2

the original data can be recovered using a cross-correlation operation (possibly in-verted).

(b) If s is displaced by one (chip) bit period, what is the result of the cross-correlations?You can shue bit 15 back to bit zero (or zero pad - the results should be similar).

2. Derive an expression for the amplitude of a standing wave resulting from a discontinuitywith purely real reflection coefficient if the incident wave is of the form V (x, t) =V0 sin(t kx)

3. Derive an expression for the path loss in dB from the expression for received signal powerwhich takes into account the medium and polarisation losses.

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