Absfract-A comparison of two radio propagation channel impulse response determination techniques is described. Presented are typical impulse response and transfer functions obtained from each measurement system. Also included for comparison are average impulse response envelopes and cumulative probability distributions for the rms delay spread of static indoor radio channels calculated from 120 measurements using each system. The comparisons show good agreement between results.
The impulse response of the indoor radio propagation channel is measured and the Angle-Of-Arrival 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 ~1 4 shifted QPSK communication system with a choice of 3 symbol rates: 145.8 Ksymbollsec, 1 Msymbollsec and 10 Msymbol lsec , over a bandwidth of 180 KHz , 1.2346 M H z 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 2. Modeling of the Indoor Channel The mathematical model chosen in this paper is due to Turin [l], which expresses the channel as a linear filter with the complex-valued impulse responsem h ( t ) = a,(t) &(t-z,(t)) e j e , ( t ) (1) k= 0 The complete model is characterized by a set of path amplitudes {ak ( t ) }, path arrival times {zk ( t ) }, and path phases { e k ( t ) } , assuming that the channel is contaminated with additive white Gaussian noise of two-sided power spectral density N0/2; j = a. 00 m 0 0 m 0 145.8 Ksymbollsec and the 1 Msymbollsec symbol rates mIn a Doppler environment, the phases { e k ( t ) b are without significantly affecting the performance of the receiver. It is also shown that for those two rates, channe1 encoding improves the speech quality only slightly, able speech quality.
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