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We present field experiment results on multiple input multiple output (MIMO) precoding using orthogonal frequency division multiple access (OFDMA) in the E-UTRA downlink. We measured the throughput performance of 4??4 MIMO precoding with 1- to 4-stream transmission. Time variation characteristics of throughput, SINR, and antenna correlations are compared to evaluate the selection criteria for the...
In this paper we consider the CQI reporting problem in MIMO downlink with adaptive switching between single user and multiuser mode and finite rate feedback. The feedback consist of channel directional information, which is the precoding weight, and channel quality information, which is a quantized value of estimated post processing SINR. The quantization of the channel directional information causes...
This paper proposes a new integration scheme for broadcast and unicast in future OFDM system based on Dirty Paper Coding (DPC) to release the orthogonal resource allocation limitation to systems today. Based on the proposed DPC integration architecture, we focus on one-dimensional DPC to optimize the unicast throughput as well as guarantee the coverage of broadcast. It is shown that there is inevitable...
In this paper we reduce the feedback overhead in two-stream MIMO with per stream link adaptation and codebook based precoding. The amount of feedback may be reduced by indicating the CQI of one stream in a differential manner. The performance of the system depends on how the differential feedback is designed. We optimize the differential feedback for the weaker data stream by considering an optimum...
In this paper, we study the possibility of throughput improvement through precoding in OFDMA based wireless systems with limited channel feedback. Precoding can increase the overall system throughput by selecting the use of higher modulation and coding schemes (if there are any) in each physical resource unit (PRU) under a maximum bit error rate constraint. For a specific form of precoding that we...
We consider the downlink of a multi-user MIMO OFDM system in a cellular environment, where users are scheduled to the transmission resources in frequency and space. Targeting a practical solution, we assume the use of fixed DFT- based pre-coding beams at the base stations and linear receivers at the multi-antenna terminals. After having received feedback on the frequency-selective interference conditions...
In this paper, we analyze the performance of beamforming and its combination with link adaptive technologies in the presence of co-channel interference (CCI) of downlink multiple-input multiple-output (MIMO) - code division multiple access (CDMA) cellular systems. The results show that the performance of MIMO systems with beamforming will mainly be degraded by the bursty nature of the CCI.
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