This paper presents a support method for specifying communication systems. Generally, a set of requirements for a target system is partial and ambiguous to construct the whole system, namely it lacks certain necessary descriptions for the target system. To attack this problem, our method enables a designer to obtain such necessary descriptions from specifications stored in a knowledge base, namely by reusing specifications, and helps the designer to specify the target system completely. In our support method, we adopt labelled transition systems (LTSs) which are state transition graphs and are shared as a common notion by most FDTs. Therefore, our method is the common approach to FDTs. We propose a new idea about similarity berween LTSs, and propose an algorithm to suggest similar LTSs to the designer.

This paper analyzes the performance of the capacity controlled digital radio system, which controls the number of modulation levels according to the amount of traffic. These analyses are performed under thermal noise and co-channel interference. As a result, the throughput improvement is approximately 16 times comparing with the fixed capacity system which has the designed outage probability of 0.1%. Theoretical results are applied to the future mobile communication system which utilizes TDMA access method or burst co-dec, and it is found that the reuse distance can be improved to 1/5 times when the designed outage probability is 0.1%.