Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/11
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Conference Object Semi-Orthogonal User Selection for Miso Systems With Quantized Feedback(Institute of Electrical and Electronics Engineers Inc., 2008) Khanfir, Hajer; Le Ruyet, Didier; Özbek, BernaFor MISO multi-user downlink wireless communication system with precoding at the transmission, the channel state information at the transmitter can provide tremendous capacity gains. However, the amount of feedback data increases with the number of users in the cell and the number of transmit antennas. In this paper, we study on different algorithms and criteria in order to significantly reduce the amount of feedback data. We associate the classical norm criterion with a criterion based on the orthogonality between the user channels. Without cooperation between the users, we only allow users that are semi-orthogonal to feedback their channel information (CQI and CDI) to the base station. The feedback CDI is quantized using a local grassmanian packing. We show that the proposed combined criterion with a finite feedback rate gives better performance compared to the norm criterion. Furthermore we show that the performance is not affected by CQI quantization.Conference Object Citation - WoS: 2Citation - Scopus: 3Performance of Semi-Orthogonal User Selection for Multiuser Miso Systems(Institute of Electrical and Electronics Engineers Inc., 2008) Le Ruyet, Didier; Khanfir, Hajer; Özbek, BernaIn MISO multiuser downlink wireless communication systems with precoding at the transmission, the capacity depends on the channel state information at the transmitter. Since the feedback data rate increases with the number of users in the cell it is important to perform a selection of the users at the receiver. In this paper, we evaluate the performance of different user selection algorithms at the receiver side through the noisy uplink channel. We evaluate the effect of the noisy channel on the classical norm criterion and on a criterion based on the orthogonality between the user channels. Without cooperation between the users, we only allow users that are semi-orthogonal to feedback their channel information as analog and quantized information to the base station through the noisy uplink channel. We propose an algorithm to reduce the noise effect on the analog feedback for semi-orthogonal user selection algorithm. We show that the semi-orthogonal criterion with quantized feedback gives better performance compared to the norm criterion for perfect and noisy uplink channels.