A spectrum efficient technique for cordless telephone access to ISDN

In both the FDMA and TDMA type systems proposed, a particular radio channel or time slot can either be allocated to a voice handset or a data handset and not both. The allocation mechanism assumes that a symmetrically duplex channel or slot is continuously required. The authors propose an alternative allocation mechanism that takes advantage of the fact that a symmetrically duplex channel is not continuously required during an interactive conversion. Their method is based on an adaptive conversational speech transmission technique proposed by Paratz and Jones (1985). The technique relies on detecting the different modes (talk, listen and double-talk) of an interactive conversation and permits different transmission bit rates in each of the modes without noticeably degrading the subjective quality of the speech. They identify two main advantages of applying the technique to cordless telecommunication systems. Firstly, the use of silence detection means that on average, each call has a lower cochannel interference contribution and thus a higher system voice capacity can be expected. The simulation results show that this is indeed the case. Secondly, it is possible to transmit packet data, at appropriate times, over a slot or channel that has been allocated to a conversation. The transmission format that allows voice and data to be multiplexed onto a single channel or slot