A model for the overall cost of radio access ports to serve a given geographical area is developed. It is shown that systems comprising large numbers of closely spaced radioports can be accurately modeled by a uniform geometric array of circular coverage patterns. Based on empirical data, a least-squares cost representation of radioports as a function of their composite radiated power is developed. Finally, the total cost function is developed and shown to be convex. An example demonstrates a nearly 6:1 range in system cost for radio access depending on the selection of radioport power and channel capacity.

Wireless data services and systems represent a rapidly growing and increasingly important segment of the communications industry. In the paper the authors present an overview of this field, emphasizing three major elements: (1) technologies utilized in existing and currently planned wireless data services, (2) issues related to the performance of these systems, and (3) discernible trends in the continuing development of wireless data systems. While the wireless data industry is becoming increasingly diverse and fragmented, one can identify a few mainstreams which relate directly to users requirement for data services. On one hand, there are requirements for relatively low-speed data services supporting mobile users over wide geographical areas, as provided by mobile data networks. On the other hand, there are requirements for high-speed data services in local areas, as provided by wireless LANs. The system-level issues are somewhat different for these two categories of services, and this has led to different technology choices in the two domains, which the authors discuss in the paper.>

The problem of computing the probability of undetected error is considered for linear block codes used for error detection. The recent literature is first reviewed and several results are extended. It is pointed out that an exact calculation can be based on either the weight distribution of a code or its dual. Using the dual code formulation, the probability of undetected error for the ensemble of all nonbinary linear block codes is derived as well as a theorem that shows why the probability of undetected error may not be a monotonic function of channel error rate for some poor codes. Several bounds on the undetected error probability are then presented. We conclude with detailed examples of binary and nonbinary codes for which exact results can be obtained. An efficient technique for measuring an unknown weight distribution is suggested and exact results are compared with experimental results.

Expressions for probability of block error,P_{f}(M,N), the probability of more thanMerrors in a block ofNdigits, are derived for binary signaling over a channel with very slow nonselective Reyleigh fading and additive Gaussian noise. The analysis is applicable to noncoherent FSK, coherent FSK, and coherent PSK signaling. An asymptotic expression for the block error probability, suitable for high signal-to-noise ratio, is also derived. Computations ofP_{f}(0,N)are presented for a broad range of error probabilities and block sizes, and the characteristics of block error probabilities for the fading and nonfading cases are compared.

This paper describes the application of selected block and convolutional coding techniques to digital transmission over an HF radio channel. Performance results are presented for interleaved binary Bose-Chaudhuri-Hocquenghem (BCH) codes, interleaved two-stage concatenated codes, and diffuse convolutional codes. The performance results are based upon raw error data recorded in transmission over a 640-km HF path, with various data runs representing the typical effects of frequency-selective and non-selective fading, atmospheric impulse noise, and interference from other users of the HF band. The performance of binary BCH codes with bit interleaving is presented and the selection of a code to meet a specified performance criterion is described. The sensitivity of specific codes to changing channel conditions is presented, along with the cost, in terms of interleaving, of designing for one set of channel conditions rather than others. Concatenated codes are discussed as a means of effective error control on channels with clustered errors. Performance data are presented for selected two-stage codes used with inner-stage word interleaving and the effects of varying certain of the code parameters are shown. Emphasis is placed on code designs that use the inner-stage code only for error detection and the outer-stage code mainly for erasure filling with only a small amount of symbol error correction. The impact of error clustering on the performance of concatenated codes is discussed. Two diffuse convolutional codes are evaluated with the use of recorded error data in computer simulations of their threshold-decoding algorithms. Performance of various configurations of these convolutional codes is given and a comparison is made with that of a simple block coding scheme having the same decoder storage requirements. The various coding techniques studied are compared on the basis of achievable performance as well as certain factors affecting the feasibility of implementation.