Proposal of design method for fixed wireless telecommunication in 400-MHz band and measurements of propagation inside office buildings

There is no clear design guide for fixed wireless links for instrumentation in office buildings. In fact, there are no quantitative data for the propa gation and fading characteristics to be utilized in link design. This artic le intends to provide a design guide for intermittent communication links f or instrumentation in office buildings. The approach is as follows. The cas e where only instantaneous variation with time exists is considered. The re ceiver power level required to satisfy the specified transmission quality i s determined. The variation of the central value depending on the site is r epresented as a function of the distance between the transmitter and the re ceiver. By superposing the variation of the central value of the site on th e specified distance and variation of the instantaneous value, the zone per iphery outage probability is derived, based on the case where the required transmission quality is not maintained. Then, a design guide based on the c ommunication distance is proposed so that the outage probability is kept be low the specified value. The communication completion rate is measured quan titatively by a long-term check of communication incompletion cases. The pr opagation characteristics of electromagnetic waves are measured for the 400 -MHz band in an actual office environment. It is shown by experiments that the variation of the received power level follows the Rayleigh distribution and the distance attenuation follows an exponential function, as in a wave guide. Design of a link is attempted for an air-conditioner wireless teleco ntrol system, using the proposed communication distance estimation based on coefficients determined by experiment. The communicable distance is estima ted as 21 m on the same floor with a seven-fold code redundant selective SD antenna. It is estimated that the required transmission quality cannot be realized in communication to adjacent floors. The communicable distance is estimated as up to 14 on in the same floor by the selective SD antenna, whe n the seven-fold extended code is not used. (C) 2000 Scripta Technica.