Semi-blind Receiver Research Articles

Sobre o Desempenho de Receptores à Taxa de Símbolos em Canais Contínuos

Symbol-sampled receivers have had their performance evaluated via Forney's discrete-time transversal filter (DTfF) model for the equivalent channel, which contains a standard matched filter and thus assumes previous knowledge of the continuous-time channel impulse response. If the continuous channel is unknown then the DTfF model provides only an upper bound on the system performance. In this paper, we quantify theoretically the performance loss of an alternative, more realistic model for the equivalent discretetime channel relative to the DTTF model, in terms of information capacity. Moreover, the loss is calculated as a function of the parameters of the transmit filter, which is assumed to be a root-raised cosine filter. We then show by means of computer simulations that this performance loss for the case of an iterative, symbol-sampled, semi-blind receiver, with combined maximum-a-posteriori equalization and turbo decoding can be negligible, which agrees with the theoretical prediction.

Iterative Semiblind Multiuser Receivers for a Space–Time Block-Coded MC-CDMA Uplink System

Iterative multiuser detection and space-time coding are two promising techniques to improve the capacity and performance of coded multiuser systems in wireless channels. In this paper, we present iterative multiuser detection schemes for a space-time block-coded multicarrier code-division multiple-access system with multiple transmit and receive antennas. We consider a more general case of an uplink system in the presence of both intra- and intercell interferences. We propose two types of iterative semiblind space-time receivers for such an uplink environment. The first is based on the minimum mean-square error criterion and the second is a hybrid scheme based on a combination of parallel interference cancellation and linear multiuser detection. These iterative receivers are derived, using a subspace approach, which utilizes known users' information for the computation of log-likelihood ratios (LLRs) while blindly suppressing the unknown interference. The LLRs are refined successively during the iterative process by using the extrinsic information available through decoding of all known users. A turbo code is used for channel coding. Simulation results in a frequency-selective Rayleigh-fading environment are presented to verify the performance of the proposed schemes.

Iterative semi-blind multiuser detection for coded mc-cdma uplink system

We propose two types of iterative semi-blind receivers for coded multicarrier code-division multiple-access (MC-CDMA) uplink systems in the presence of both intracell and intercell interference. The first is based on the minimum mean-square error criterion, and the second is a hybrid scheme, consisting of parallel interference cancellation and linear multiuser detection. These iterative receivers utilize known users' information for the computation of log-likelihood ratios (LLR) while blindly suppressing unknown interference. The LLR are refined successively during the iterative process through decoding of all known users. Simulation results demonstrate that the proposed iterative semiblind methods offer substantial performance gain over conventional noniterative and nonblind iterative receivers.

Condition Estimates

Condition Estimates