A Study On The Methods Of Optimizing The Speech Quality Of PHS In The High Traffic Regions

As a personal wireless communication system, PHS (Personal Handy-Phone System) holds a dominant position in the communication market because of the characteristics of environmental protection, lower price, etc. In recent years, with the rapid development of the services of GSM, narrow band CDMA and 3G, PHS is confronted with great challenges. And the key for PHS to survive and develop in the communication market is to improve the speech quality through optimizing the network.This article mainly analyses the wireless signal transmission theory about PHS, the modulation mode and the technology of air interface. It also does some further research on the covering density among CS (Cell Station) in the high traffic region in the PHS network, LAC(Local Area Cell) planning, synchronization and handover which influence the speech quality. In addition, the author proposes one kind of high traffic region speech quality optimization model in the light of the network experiences accumulated in the work. This model is applied to the typical regions in Lanzhou city and the author has found the present problems existing in the regional network through the DT (Driving Test): the CS parameters of switching threshold value are not reasonable and the LAC is irregular in high traffic region. In view of these problems, the author proposes and carries out the optimization scheme. Finally the author contrasts and evaluates the network performance index and the result has indicated that the speech quality in this region has been greatly improved through the optimization. For instance, the average speech quality MOS (Mean Opinion Score) value increases from 1.97% to 3.16%, raising 1.19 percentage points, and the smallest speech quality MOS value increases from 1.00% to 1.27%, raising 0.27 percentage points. The utilization of the network has been greatly improved and the customers are more satisfied with the network.