900 MHz digital cordless telephone

The paper discusses several aspects of cordless telephony which are relevant to systems being discussed for use in the UK in the future. A variety of methods of arriving at traffic estimates are considered, including studies of population density in urban and suburban London. From these estimates it is shown that an allocation of at least forty channels will be needed to satisfy the demand of domestic and small business users. Three analogue and one digital modulation systems are considered, and it is shown that the digital system offers better use of the spectrum than the analogue systems. Additionally, the digital scheme allows convenient implementation of time-division duplex transmission, as well as ongoing call-quality monitoring. The paper looks at the merits of allocating one common channel for signalling purposes and compares these with the advantages of a simpler system, where the signalling information is carried on the speech channels. It is shown that significant extensions of battery life can be achieved by using a common signalling channel. Finally, the paper considers some of the implications of the time-division duplex system on receiver design.