Diversity for indoor radio communications

The impulse response of the indoor radio propagation channel is measured and the angle-of-arrival (AOA) of the distinct paths is resolved with a 5 degree resolution. The resolved AOA is used to model the indoor environment for the purpose of (computer) simulating a digital cellular system with diversity. The modulator consists of a π/4 shifted QPSK communication system with a choice of 3 symbol rates: 145.8 Ksymbol/sec, 1 Msymbol/sec and 10 Msymbol/sec, over a bandwidth of 180 kHz, 1.2346 MHz and 12.346 MHz, respectively, accommodating 18, 123 and 1234 voice channels, respectively. It is shown that equalization and maximum likelihood sequence estimation can be avoided for both the 145.8 Ksymbol/sec and the 1 Msymbol/sec symbol rates without significantly affecting the performance of the receiver. It is also shown that for those two rates, channel encoding improves the speech quality only slightly and that space diversity is necessary to obtain an acceptable speech quality