This paper describes an algorithm for estimating loss probability in a circuit-switched network. The estimate obtained by the algorithm is also compared with an estimate obtained through simulation.

In many mobile satellite communication systems specular multipath exists and acts as a distortion to the transmitted message stream. In most cases there is a singular specular return which can be characterized by a delay and reflection coefficient. If this return is viewed as intersymbol interference on the channel, then it is possible to consider the resulting channel as modeled by a finite state machine and process the received data stream optimally using the Viterbi algorithm. This paper develops such a scheme and derives a performance bound. A suboptimum scheme is also developed which is less sensitive to inaccurate knowledge of the multipath parameters. Performance bounds for the suboptimum scheme are also developed.

In this correspondence paper a technique for estimating the minimum number of frequencies required for Urban Mobile Radio Communication is presented. The technique is algebraic in origin and can be implemented as a computer algorithm.

The existence of binary sequences with specific aperiodic autocorrelation and cross correlation properties is investigated. Relationships are determined among the size of a sequence set, the length of the sequences n, the maximum autocorrelation sidelobe magnitude\alpha, and the maximum cross correlation magnitude\beta. The principal result is the proof of the existence of sequence sets characterized by certain combinations ofn, \alpha, and\beta. The proof makes use of a new lower bound to the expected size of sequence sets constructed according to an explicit "random coding" procedure. For largen, the sequence set size is controlled primarily by the cross correlation constraint\beta. Two consequences of the existence theorem are 1) a demonstration that large sequence sets exist for which the maximum autocorrelation sidelobe and cross correlation magnitudes vanish almost as fast as the inverse square root of the sequence length(l/\sqrt{n}); 2)a new proof of the Gilbert bound of coding theory.

The problem of buffer overflow in variable-length-to-block and block-to-variable-length coding of fixed-rate finite-state homogeneous Markov sources for transmission through fixed:rate noiseless channels is investigated. Asymptotically optimal converging upper and lower bounds on the probability of overflow are derived. They decrease exponentially with the buffer sizeB. The least ratesR(\gamma)that achieve exponents\gammafor both coding methods are obtained, as are the corresponding optimal word assignments. It is shown that for the class of state-calculable sources, variable-length-to-block and block-to-variable-length ratesR(\gamma)are equal.

Variable-length-to-block codes are a generalization of run-length codes. A coding theorem is first proved. When the codes are used to transmit information from fixed-rate sources through fixed-rate noiseless channels, buffer overflow results. The latter phenomenon is an important consideration in the retrieval of compressed data from storage. The probability of buffer overflow decreases exponentially with buffer length and we determine the relation between rate and exponent size for memoryless sources. We obtain codes that maximize the overflow exponent for any given transmission rate exceeding the source entropy and present asymptotically optimal coding algorithms whose complexity grows linearly with codeword length. It turns out that the optimum error exponents of variable-length-to-block coding are identical with those of block-to-variable-length coding and are related in an interesting way to Renyi's generalized entropy function.