Simulation and measurements associated with the Olympus ku-band SSTDMA experiment.

The increase in demand for channel capacity and the limitations in satellite power and frequency spectrum is leading to requirements for advanced multiple beam antenna systems with frequency reuse. The concept of the Olympus satellite evolved from the fact that new technologies and methods are to be explored for future satellites. The role of Olympus can be seen in both the development of earth station networks and at the same time the satellite requirements for the future satellites. It is a step between advanced transparent repeaters and the future intelligent satellite with on-board processing. A review of commercial and experimental satellites employed in the European region is given in the thesis. The services offered by these satellites and the access methods used are discussed with particular emphasis on business services. The new research work reported was done on the experiments related to the Olympus SS-TDMA payload. First a survey of commercial TDMA systems was performed and their capabilities discussed in detail for the SS-TDMA experimental application. The Olympus payload description and link budget analysis was performed in order to identify the size of the earth station required for these networks. The performance of the satellite link was simulated using BOSS software package together with some earlier simulation using the TOPSIM software package. The methods of BER estimation used are investigated and various results compared. These simulations covered most aspects of the RF (degradation due to TWTA non-linearity, fading, carrier spacing, co-channel interference) and some aspects of the baseband circuits. These simulation results have been compared with the experimental results and were found to be in close agreement. Thus giving confidence in the simulation methods used. In SS-TDMA the problem of acquisition and synchronisation is very important. In this respect the design of the acquisition and synchronisation unit (ASU) is discussed in detail. The resulting ASU was interfaced with the reference station of the commercial TDMA system for the first phase of the SS-TDMA experiments. Finally we present results of various network control methods for the SS-TDMA network, including the buffer requirement for the on-board clock control with the sidereal day clock correction. The ASU design, its interface to the reference TDMA terminal and successful operation with the reference station in acquiring and synchronising with the satellite switch provided the real time operation of the SS-TDMA scheme. The operation was conducted experimentally using the BTRL (British Telecom Research Labs) experimental earth station at Martlesham both in the "reference station loopback" and "reference station and traffic station" configuration via the the SS-TDMA switch. Full details of the experiments and comparison with systems simulations are presented in the thesis