Armelle Wautier

Estimation of noise and interfering power for transmissions over Rayleigh fading channels

The topic of the paper is the evaluation by the receiver of the power of noise and co-channel interferences altering transmissions over Rayleigh fading channels. In our study we display results for TDMA mobile radio systems such as GSM or EDGE, but the approach is valuable for CDMA as well. We propose two methods to carry out the evaluation of the signal to noise ratio (SNR) or the carrier to interference ratio (CIR) at each received burst. The accuracy of these methods are derived in a closed form in the case of additive noise. In the case of interferences, we display results of simulations for both methods when the number of interferers is between 1 and 6.

New optimal hard decoding of convolutional codes with reduced complexity

It is well known that convolutional codes can be optimally decoded by the Viterbi algorithm (VA). We propose an optimal hard decoding technique where the VA is applied to identify the error vector rather than the information message. In this paper, we show that, with this type of decoding, the exhaustive computation of a vast majority of state-to-state iterations is unnecessary. Hence, under certain channel conditions, optimum performance is achievable with a sensible reduction in complexity.

Sensitivity of interfering power estimation to combining strategies in MC-CDMA systems

In this paper, the problem of accuracy in noise/interfering power estimate for an MC-CDMA receiver is considered. This quality parameter is a key feature in the link control for next generation wireless systems. It is used for bit loading, power control, dynamic frequency selection, or even handover. Adaptation of physical layer can also be based on this quality estimate. Therefore, its accuracy is of paramount importance when designing such adaptive systems. The sensitivity of the noise/interfering power estimate are compared and discussed for different diversity combining schemes viz: maximal ratio combining (MRC), equal gain combining (EGC), and selective combining (SC).

Accuracy of interfering power estimation in MC-CDMA systems

In this paper, we present an analytical approach to study the power estimate of the interference in a MC-CDMA transmission scheme. The receiver is implementing a simple RAKE architecture that is not near-far resistant. The regenerated signal (RS) technique is applied on a symbol basis for power estimation of the jamming signal. An exact equation of this estimate is obtained for L uncorrelated diversity branches, and the impact of diversity order is discussed.