The probability distribution of the diameter of a network model consisting of a complete digraph with positive integer random edge costs is considered. Edge costs are chosen independently for each node pair according to common probability distributions for each edge direction. Bounds and some sharp limit results for the diameter distribution in the limit as the number of nodes tends to infinity are derived. In addition, limit bounds are determined for the distribution of the number of hops in a shortest path between two arbitrary nodes in the graph. Numerical examples are presented to illustrate these results.>

The effect of handoff techniques on cell coverage and reverse link capacity is investigated for a spread spectrum CDMA system. It is shown that soft handoff increases both parameters significantly relative to conventional hard handoff.>

An improved series of bounds is presented for the other-cell interference in cellular power-controlled CDMA. The bounds are based on allowing control by one of a limited set of base stations. In particular, it is shown that the choice of cellular base station with least interference among the set of N/sub c/>1 nearest base stations yields much lower total mean interference from the mobile subscribers than the choice of only the single nearest base station.>

The probability distribution of the shortest path cost from a source node to an arbitrary destination node is considered for a random network model consisting of a complete digraph with positive integer random edge costs. Edge costs are chosen according to a common probability distribution for each direction. For this model, the joint distribution of the number of nodes which have a given sequence of shortest path costs from an arbitrary source node is determined explicitly. An expression is then obtained for the distribution of the shortest path cost between two arbitrary nodes using this joint distribution. The main result is the derivation of tight bounds and a sharp limit result for the distribution of the shortest path cost as the number of nodes tends to infinity. Numerical examples are presented to illustrate these results.>

This work presents an approach to the evaluation of the reverse link capacity of a code-division multiple access (CDMA) cellular voice system which employs power control and a variable rate vocoder based on voice activity. It is shown that the Erlang capacity of CDMA is many times that of conventional analog systems and several times that of other digital multiple access systems.>

Performance of a wideband multipath-fading terrestrial digital coded communication system is treated. The analysis has applications to a cellular system using direct-sequence spread-spectrum code-division multiaccess (CDMA) with M-ary orthogonal modulation on the many-to-one reverse (user-to-base station) link. For these links, power control of each multiple-access user by the cell base station is a critically important feature. This feature is implemented by measuring the power received at the base station for each user and sending a command to either raise or lower reverse link transmitter power by a fixed amount. Assuming perfect interleaving, the effect of the power control accuracy on the system performance is assessed.>

A Markov model which approximates the behavior of networks that transport messages of varying priority classes is developed. The model is shown to accurately predict behavior for a tandem network with departures and an unidirectional loop network. In the cases which required approximation, the model was validated by performing extensive computer simulation and comparing it with analytical results.>

Models and analytical techniques are developed to evaluate the performance of time-synchronous packet networks with priority queueing disciplines. In cases which require approximation, the model was validated through extensive computer simulation and compared to analytical results. A local first-order Markov model based on a burstiness criterion is used to approximate the delay incurred by each class of traffic in a network. The application of this model to selected networks shows that it accurately predicts behavior of tandem (i.e. with and without departures), unidirectional, and bidirectional loop networks.>

In this paper, models and analytical techniques are developed to evaluate the performance of the backbone networks of discrete-time linked-cluster packet networks. The theoretical results are validated by extensive computer simulation. The results of this research may be applied to the design of multiprocessor networks, local area networks, and cellular, terrestrial, and satellite packet networks.

Burst transmission of digital data and voice has become commonplace, particularly in satellite communication systems employing time-division multiple-access (TI)MA) and packet demand-assignment multiple-access (DAMA) techniques. In TDMA systems particularly, phase estimation on each successive burst is a requirement, while bit timing and carrier frequency can be accurately tracked between bursts. A class of nonlinear estimation algorithms is described to estimate the unknown phase of a carrier which is fully modulated bym-ary PSK modulation. Performance of the method is determined in closed form and compared to the Cramér-Rao lower bound for the variance of the estimation error in the phase of an unmodulated carrier. Results are also obtained when the carrier frequency is imprecisely known. Finally, the effect of quantization and finite read-only-memory (ROM) implementation of the nonlinearity are determined by computer simulation.