This letter addresses the problem of finding a tractable expression for the symbol error outage (SEO) in flat Nakagami-m fading and shadowing channels. We deal with M-ary phase shift keying (M-PSK) and quadrature amplitude modulation (M-QAM) which extends our previous results on BPSK signaling. We propose a new tight approximation of the symbol error probability (SEP) holding for M-PSK and M-QAM signals which is accurate over all signal to noise ratios (SNRs) of interest. We derive a new generic expression for the inverse SEP which facilitates the derivation of a tight approximation of the SEO in a lognormal shadowing environment.

The roll-out density of wireless local area networks (WLANs) has recently witnessed a dramatic increase and is currently reaching saturation levels. The frequency bands designated to WLANs does not suffice any more to provide non-overlapping, and hence interference-free, communication bands. A large body of research has been dedicated to a wide variety of optimum maximum likelihood sequence estimation (MLSE) and sub-optimum in-band interference mitigation techniques. Our contribution lies in a reduction of the state-space of a MLSE detector in the case of a desired WLAN receiver experiencing delayed interference from some other transmitters operating in partially overlapping spectral bands and over independent frequency-selecting block-fading channels. Based on the formulation of the optimum receiver, we derive a sub-optimum receiver of reduced complexity and demonstrate its satisfactory performance in the context of strong interference.

The deployment of wireless local area networks (WLANs) has recently gained in popularity with roll-out densities often reaching saturation levels. The frequency bands designated to WLANs do thus not suffice anymore to provide non-overlapping, and hence interference-free, communication. Prior research has therefore been dedicated to a wide variety of mainly cochannel interference mitigation techniques. Our contribution lies in the performance analysis of the more realistic case of spatially close WLAN systems interfering asynchronously in DSSS mode and on adjacent channels. The authors expose the performance of optimum and sub-optimum multiuser detection maximum likelihood sequence estimators (MUD-MLSEs) under varying conditions, e.g. level of interference, degree of spectral overlap, etc. This facilitates a better understanding and design of future interference-limited WLAN systems. The performance results are also important to spectrum policy makers, allowing to knowledgeably estimate the degree of tolerated interference in license exempt bands.

In this paper, a low complexity multicode MMSE chip-level channel equalizer for the downlink UMTS FDD mode is proposed. This equalizer has a Rake-like structure and does not need the knowledge of the spreading codes to compute the equalizer filter coefficients. Moreover, the equalizer depth is determined automatically using the knowledge of the channel impulse response and the noise variance. Thus, the structure of the equalizer changes as the channel conditions change and the equalizer can be reduced to a Rake receiver if the depth is equal to one chip (e.g., in low signal-to-noise ratio conditions and/or in weak frequency selective channels). This property is very important and can be used to optimize the power consumption, which is a major constraint that has to be accounted for in the user equipment design.

Orthogonal space-time block codes allow utilising the diversity provided by multiple-input-multiple-output communication channels, thereby decreasing the error probability for a given communication rate. The contribution of this paper is the derivation of closed-form expressions of the symbol error probability of distributed codes deployed over Nakagami flat fading channels with different channel gains and fading parameters

In this paper, we propose a low complexity multi-code chip-level channel equalizer for the downlink UMTS FDD mode. Both block form and filter form implementations are considered. The proposed receiver can be of ZF or MMSE type, and consists of a linear equalizer followed by a bank of correlators corresponding to the spreading codes, and a decision device. It has a Rake-like structure and does not need the knowledge of the spreading codes to compute the equalizer filter coefficients. We show how to compute the equalization matrix at low complexity, and we give a measure of the upper-bound of the equalizer filter depth. Simulation results are given to corroborate the good performance of the equalizer in the high speed downlink packet access (HSDPA) scenario

In this paper, a new algorithm for multipath channel estimation by means of the Common Pilot Channel (CPICH) in downlink WCDMA-FDD is presented. The estimation is performed by using a Single Most Likely Replacement (SMLR) algorithm specifically derived for complex baseband signals where a Bernoulli-Gaussian (BG) model is introduced for the multipath channel. In the proposed algorithm, an interference cancelling technique is associated to the SMLR to enhance its performance. The proposed algorithm performs very well; it yields a satisfactory performance at a moderate extra computational cost compared to the SMLR.

We aim to present a comparative study of the performances, in terms of the mean PSNR (peak signal-to-noise ratio), of a UMTS/TDD transmission system for H.263 compressed and turbo-coded video sequences. Several parameters are varied, among them: the rate of occurrence of intra coded frames; the video compression level; the bit error rate of the transmission channel. We also present a methodology for determining the best scheme for repartition of the global channel bandwidth between source and channel coding, in order to minimize the global distortion on the transmitted sequences.

We study the behaviour of a UMTS/TDD synchronous downlink receiver, under different scenarios. Computer simulations were conducted to compare the overall system performances obtained with turbo coding to the convolutional coded and channel non coded systems. The propagation environment is a six-path channel with Rayleigh fading amplitudes and fixed delays. Moreover, we propose a method for reducing the iteration number via a cyclic redundancy check (CRC), and estimate the channel decoding complexity to be expected, for different channel conditions.

In the downlink TD/CDMA multiple access scheme through a multipath channel, the use of a short complex code enables a strategy of multi-user detection with great sensibility improvement compared to the traditional matched filter. Nevertheless, the performances are damaged compared to the situation with an ideal channel, more especially as the number of users increases. In this paper, we first use the cross-spectral matrix of the aliased coded channels to recall linear multi-user detector (ZF and MMSE) and express a degradation factor of interference and noise to signal ratio due to a non-ideal channel, with or without fading. The degradation and bit error probability are then computed in the concrete situation of indoor and pedestrian channel environments in order to show the great benefit of one or two supplementary sensors at the reception system.