The performance of a single-user, ultra-wideband (UWB) communication system employing binary block-coded modulation with pulse-position modulation (PPM) or on-off keying (OOK) and operating in indoor multipath channels is considered. We examine the tradeoff between receiver complexity and performance for the case of RAKE receivers with maximal-ratio combining (MRC). The derived expressions are evaluated numerically with measured UWB channel data for various cases.

The performance of a single-user ultra-wideband (UWB) communication system employing binary block-coded pulse-position modulation (PPM) and suboptimal receivers in multipath channels is considered. The receivers examined include a RAKE receiver with various diversity combining schemes and an autocorrelation receiver, which is used in conjunction with transmitted reference (TR) signaling. A general framework is provided for deriving the performance of these receivers in multipath channels corrupted by additive white Gaussian noise (AWGN). By employing previous measurements of indoor UWB channels, we obtain numerical results for several cases which illustrate the tradeoff between performance and receiver complexity.

This paper examines the asymptotic (M/spl rarr//spl infin/) performance of M-ary frequency-shift keying (M-FSK) in multi-channels, or multiple frequency-nonselective, slowly fading channels, with coding, side information, and diversity reception. In particular, Reed-Solomon (RS) coding is considered in conjunction with the ratio-threshold test (RTT), which generates side information regarding the reliability of received symbols. The asymptotic performance of orthogonal signaling in multichannels with maximal ratio combining (MRC), postdetection equal gain combining (EGC), hybrid selection combining (H-SC), and selection combining (SC) is derived for an arbitrary statistical fading model and diversity order. The derivations reveal that coherent and noncoherent implementations of diversity combining schemes yield the same performance asymptotically. In addition, the asymptotic results are evaluated assuming a Nakagami-m fading model, and the effect of fading severity, diversity order, code rate, and side information upon the performance of the various diversity combiners is investigated. The minimum signal-to-noise ratio (SNR) required to achieve arbitrarily reliable or error-free communication, as well as the associated optimal RS code rate, are determined for various cases.

This paper examines the asymptotic performance of M-ary orthogonal modulation with noncoherent square-law detection and combining in Rayleigh fading. The analysis takes into consideration Reed-Solomon coding and evaluates the gain provided by the ratio-threshold test (RTT) which generates side information regarding the reliability of received symbols. The minimum received signal-to-noise ratio (SNR) required for error-free communication and the optimal code rate are derived for arbitrary orders of diversity. These asymptotic results are then extended to a direct-sequence code division multiple access (DS-CDMA) system with frequency-selective fading.

The decision to attempt or suspend transmission is cast as a stochastic control problem with imperfect state information. By employing a dynamic programming formulation, the tradeoff between high throughput and energy efficiency is resolved in a flexible cost structure over which the optimization is performed. The optimal policy is derived and shown to be a threshold rule that varies with the memory present in the error process. A suboptimal implementation of the policy indicates that the protocol always favors attempting transmissions when the memory is low. As the channel memory increases, the protocol suspends transmission for longer durations after a packet failure.