Solomon W. Golomb was born into an intellectually gifted family in Baltimore, MD. His father, a polyglot, was a professor at Baltimore Hebrew College and Sol grew up speaking several European and Middle Eastern languages. In adulthood he would add at least two East Asian languages to the point of being able to lecture in both. With this background he was also expert in the etymology of numerous words and expressions in a variety of language families and he never missed an opportunity to so enlighten conversation with friends and colleagues.

Wireless personal communication has existed for about a quarter century. In the 1980's analog FDMA served a small mostly North American base of wireless telephony users. The 1990's witnessed the start of widespread worldwide digital telephony and limited data service, categorized as 2nd Generation, employing two conflicting technologies, TDMA and CDMA. The first decade of the new century brought full wireless data and Internet connectivity with two competing 3rd Generation CDMA implementations: CDMA2000 and WCDMA. For the second decade beginning in 2010, early indications point to convergence upon a single 4th Generation high speed data technology, OFDMA, generally referred to as Mobile WiMax for which a standard 802.16e has recently been adopted. After describing this historical evolution, we shall address the challenges and opportunities of both 3rd and 4th Generation Wireless Broadband service.

An intuitive shortcut to understanding the maximum a posteriori (MAP) decoder is presented based on an approximation. This is shown to correspond to a dual-maxima computation combined with forward and backward recursions of Viterbi algorithm computations. The logarithmic version of the MAP algorithm can similarly be reduced to the same form by applying the same approximation. Conversely, if a correction term is added to the approximation, the exact MAP algorithm is recovered. It is also shown how the MAP decoder memory can be drastically reduced at the cost of a modest increase in processing speed.

For original paper see ibid., vol.43, no.6, p.2028, 1995. This brief comment points out that the comparison is between a quasi-optimal metric for a word-by-word coding and interleaving technique and a sub-optimal metric for a bit-by-bit technique. When the sub-optimal receiver for the latter is replaced by an improved quasi-optimal metric, the difference in performance of the two techniques is much reduced for slow fading, while for fast fading, the bit-by-bit scheme is superior.

We explain how to obtain the weight enumerator and the performance of linear block codes formed in several distinct ways from a convolutional code.

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.>

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 spread-spectrum multiple-access (SSMA) communication system is treated for which both spreading and error control is provided by binary PSK modulation with orthogonal convolution codes. Performance of spread-spectrum multiple access by a large number of users employing this type of coded modulation is determined in the presence of background Gaussian noise. With this approach and coordinated processing at a common receiver, it is shown that the aggregate data rate of all simultaneous users can approach the Shannon capacity of the Gaussian noise channel.>

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.

This paper describes a microprocessor-based modem developed for use in a packet switching network over satellite channels. This digital modem can process both BPSK and QPSK packets with near optimum error rate performance over channels with marginal signal energy-to-noise density ratio. Of principal concern is the development of the discrete time algorithms which form the basis of the microinstruction program. The processing of a packet can be decomposed into two basic stages: (1) the detection of the packet preamble and the rapid estimation of signal parameters (symbol timing and carrier frequency offset) for the specific packet, and (2) the demodulation of the data portion of the packet including the tracking of both symbol timing and carrier offset phase, phase ambiguity resolution and data symbol estimation. The paper concludes with details on the performance of the modem under operational conditions and a brief discussion of implementation of the processor.

A new contention-based demand assignment protocol (CPODA) is described. The protocol is designed to handle packetized data and voice traffic in a multiple access satellite broadcast channel, where the channel is typically shared by hundreds of earth stations. A sophisticated traffic environment is assumed, including multiple priority and delay class distinctions, variable message lengths, and an arbitrary load distribution among the stations. In addition, stations may have different receiving rate capabilities. The CPODA protocol is part of a broader research project concerned with developing protocols for a one-hop satellite network (SATNET). The CPODA and other protocols are currently undergoing experimental evaluation using an INTELSAT IV-A satellite and four earth stations in the Atlantic region.

For memoryless discrete-time sources and bounded single-letter distortion measures, we derive a bound on the average per-letter distortion achievable by a trellis source code of fixed constraint length. For any fixed code rate greater thanR(D^{\ast}), the rate-distortion function atD^{\ast}, this bound decreases towardD^{\ast}exponentially with constraint length.

This retrospective survey describes the major trends in information theory research during the decade of the sixties, with emphasis on channel and source coding.

For a class of generalized decision strategies, which afford the possibility of erasure or variable-size list decoding, asymptotically tight upper and lower error bounds are obtained for orthogonal signals in additive white Gaussian noise channels. Under the hypothesis that a unique signal set is asymptotically optimal for the entire class of strategies, these bounds are shown to hold for the optimal set in both the white Gaussian channel and the class of input-discrete very noisy memoryless channels.

The probability of error in decoding an optimal convolutional code transmitted over a memoryless channel is bounded from above and below as a function of the constraint length of the code. For all but pathological channels the bounds are asymptotically (exponentially) tight for rates aboveR_{0}, the computational cutoff rate of sequential decoding. As a function of constraint length the performance of optimal convolutional codes is shown to be superior to that of block codes of the same length, the relative improvement increasing with rate. The upper bound is obtained for a specific probabilistic nonsequential decoding algorithm which is shown to be asymptotically optimum for rates aboveR_{0}and whose performance bears certain similarities to that of sequential decoding algorithms.

This paper considers the performance of a communication system which transmits forTseconds the real part of a sample function of one ofMstationary complex Gaussian processes whose spectral densities are all frequency translations of the functionS_{\xi (f). At the receiver white Gaussian noise of one-sided densityN_{0}is added. The center frequencies of the processes are assumed to be sufficiently separated that theMcovariance functions are orthogonal overT. Exponently tight bounds are obtained for the error probability of the maximum likelihood receiver. It is shown that the error probability approaches zero exponentially withTfor all ratesR = (\ln M)/Tup toC= \int_{-\infty}^{\infty} [S_{\xi (f)/N_{0}] df - \int_{- \infty}^{\infty} \ln [1 + S_{\xi}(f)/N_{0}] dfwhich is shown to be the channel capacity. Similar results are obtained for the case of stochastic signals with specular components.

In a recent paper Reed and Scholtz (ibid., vol. IT-12, pp. 388-395, July 1966) analyze the error probabilities encountered in using N-orthogonal codes over a white Gaussian channel. In this correspondence the authors derive simple upper and lower bounds on these probabilities and discuss some of the implications of these bounds.

The optimum detectors for coherent and noncoherent reception of binary signals in additive Gaussian noise and the resuiting error probabilities were obtained by Helstrom [1]. In many practical communication systems a reasonable estimate of the phase of the received signal is available as the result of an auxiliary tracking operation of the carrier signal by a coherent tracking device such as a phase-locked loop. It is shown that the optimum detector for this case, which we refer to as partially coherent reception, is a linear combination of the correlation detector and the squared envelope correlation detector, which are optimum for the coherent and noncoherent cases, respectively. The error probabilities are also obtained as a function of the energy-to-noise ratio of the channel and the variance of the error in the phase estimate, which is a function of the signal-to-noise (SNR) in the tracking loop. The signal selection problem is considered in terms of these parameters.