AbstractPrivate mobile radio services have experienced for a number of years congestion of the available spectrum. Although the release of Band III has contributed significantly to alleviating the spectrum shortage, it will however, not be sufficient to accommodate the projected growth in private mobile radio (PMR). Consequently, new techniques of efficient spectrum utilisation are needed to ensure that future growth and enhancement of PMR services can be met.
The research work undertaken and presented in this thesis has been concerned with doubling the capacity of a mobile radio channel and providing a value added facility by developing an integrated voice and data transmission system. The multiplexed system developed and investigated is based on angle modulation and 12.5 kHz channeling as proposed for Band III mobile systems.
The thesis initially introduces and analyses a number of modulation strategies potentially suitable for the simultaneous transmission of speech and data over a common radio channel. Evaluation of a proposed scheme using a novel CAE simulation tool is described and relevant results presented. Prototype transmitter and receiver equipment developed to implement a speech-data multiplexed radio system is also described. Results of the system performance, obtained under simulated radio propagation conditions, are presented and the implications discussed. In particular, the interaction between speech and data message signals and other problem areas that influence the quality of the service and reliability of information transfer are identified and discussed.
Finally, proposals for future development work involving an alternative demultiplexing strategy are also presented.
|Date of Award||Mar 1988|