Cellular digital packet data overlaid on the cellular voice system
SU Yan-bing, Chao Chen · 2002
Cellular digital packet data (CDPD) is a data network designed to meet growing mobile data transmission needs. CDPD networks can stand alone or overlay on the cellular voice system. In the latter situation, they borrow idle radio channels from the analog cellular voice system, if available, to send packet data traffic. Due to trunking inefficiencies, a large number of idle analog voice channels can be found. Furthermore, the periods of time that each voice channel is idle are fairly long. There are two ways one can overlay CDPD on cellular voice: channel hopping and dedicating voice channels to CDPD. Each of them will result in degradation in voice quality. In this paper, we calculate the number of available idle voice channels and the periods of time unused in each voice channel. We also investigate channel hopping resulting from voice-data resource contention. In addition, we analyse the effect on cellular voice due to CDPD overlaid on the cellular voice system.