We consider the downlink of a power-controlled MC-CDMA network in which the base station assigns the power to each user according to its location within the cell. In particular, more power is assigned to the users near the cell boundaries in order to improve the geographical fairness in data reception. This results in a near-far effect for the users located close to the base station, which enhances the multiple-access interference (MAI) and limits the performance of conventional single-user receivers. Interference cancellation (IC) schemes may be employed to mitigate the detrimental effects of MAI. However, they require knowledge of the channel responses as well as of the noise power and strengths of the interfering signals. In this paper, we address the problem of estimating all of the above parameters using a maximum likelihood (ML) approach and exploiting pilot blocks multiplexed with the transmitted data. The estimates are then used by a non-linear detector in which an interfering signal is cancelled provided that its estimated power exceeds a given threshold. Simulation results show that the proposed scheme outperforms other existing IC-based techniques.
Parameter Estimation for Interference Cancellation in Power-Controlled MC-CDMA Downlink Transmissions
MENGALI, UMBERTO;MORELLI, MICHELE;SANGUINETTI, LUCA
2005-01-01
Abstract
We consider the downlink of a power-controlled MC-CDMA network in which the base station assigns the power to each user according to its location within the cell. In particular, more power is assigned to the users near the cell boundaries in order to improve the geographical fairness in data reception. This results in a near-far effect for the users located close to the base station, which enhances the multiple-access interference (MAI) and limits the performance of conventional single-user receivers. Interference cancellation (IC) schemes may be employed to mitigate the detrimental effects of MAI. However, they require knowledge of the channel responses as well as of the noise power and strengths of the interfering signals. In this paper, we address the problem of estimating all of the above parameters using a maximum likelihood (ML) approach and exploiting pilot blocks multiplexed with the transmitted data. The estimates are then used by a non-linear detector in which an interfering signal is cancelled provided that its estimated power exceeds a given threshold. Simulation results show that the proposed scheme outperforms other existing IC-based techniques.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
