HW 12 Problem 1. In a certain wireless channel, the delay spread T =10µsec and the maximum Doppler D spread f =0.2 kHz. The maximum propagation attenuation is 40dB. d The total power available at the transmitter is 1.08Watt. (Hint: i.e., the minimum received signal power is 0.108 mWatt.) The total bandwidth is 2 MHz For the OFDM receiver, the received noise power density is 0.1µWatts/MHz. The total 2 intercarrier interference power (for all subcarriers combined) is (f T) mWatts where T is d the OFDM symbol duration. a.) what is the minimum guard time interval for preventing intersymbol interference? b.) what is the maximum data rate (BPSK signaling) where minimum SINR is 40 (in linear scale)? Problem 2 Let the original symbol duration T be 0.1msec and the number of subcarrier is 16 (k=0:15). Guard time T for cyclic prefix is 0.02msec. The combined symbol period T G s becomes 0.12msec. Let the OFDM signal go though a time varying channel with the following 2-path model: N -- jf 2(pt ft) nn Hf(,t)= ae with N=2, a =1 for n=1,2, t =0, t =0.01msec, n 1 2 ? n n=1 th a.) For f =200Hz and f =-200Hz, find the ICI at the 8 carrier (k=7) for m=0,1,2, …,6. 1 2 m th b.) For f =600Hz and f =-600Hz, find the ICI at the 8 carrier (k=7) for m=0,1,2, …,6 1 2 m
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