PROPAGATION CONSIDERATIONS FOR THE DESIGN OF AN INDOOR BROAD-BAND COMMUNICATIONS-SYSTEM AT EHF

This paper reports the measurement and analysis of wideband propagatio n data for indoor radio channels at 40 GHz, Propagation characteristic s are reported for two open-concept office areas of different sizes in two different buildings, Also, the results of measurements in one bui lding are compared for system configurations in which either an omnidi rectional or a narrowbeam antenna is employed at a base station for co mmunications to multiple work stations with omnidirectional antennas, It is reported that, on a statistical basis, at the 90th percentile, m ultipath dispersion is the same for the two base-station antenna radia tion patterns, Dispersion was, however, found to be lower in the small er of the two measurement areas, where transmit/receive ranges were sh orter, The 90th percentile of static rms delay spread for this area wa s 19 ns compared with 45 ns for the larger area, Multipath spreads at the -25-dB relative power level were about 370 ns, compared with 440 n s in the larger area, In the larger area, global propagation loss was found to be well modeled by the one-way propagation equation with diff erent range exponents (1.5 and 4) before and after a breakpoint at a r ange of 25 m, In the smaller area, the range exponent was found to be greater, being equal to 3.5. This is considered to be a result of redu ced multipath infill, which would accompany the reduced dispersion. Te mporal fading on fixed links with omnidirectional antennas was found t o have depths such that a 14-dB fade margin is required for 99% reliab ility, Finally, spatial variations in received power at a given range indicated the requirement for a power margin between 4-7 dB for 99% re liability, These results are used at the end of the paper in a link bu dget example for a broad-band indoor extremely high frequency (EHF) di gital communications system.