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In this paper, we present and analyze a rate-adaptive multiuser orthogonal random beamforming (ORBF) system. The goal is to maximize the average spectral efficiency (ASE) while satisfying a target bit error ratio (BER) constraint. We first derive the cumulative distribution function of the post-scheduling signal-to-interference-plus-noise ratio (SINR) with a new approach. The average BER and the ASE...
It has been shown that multiuser MIMO systems have better capacity performance than single-user MIMO systems. For a large number of users, the transmitter selects a subset of users with good channels to maximize the system performance. Shannon capacity has been used most of the time as the performance measure for multiuser MIMO systems. In this paper, we consider BER as an alternative performance...
We investigate antenna-grouping algorithms, which are hybrids of beamforming and spatial multiplexing. We partition transmit antennas into several groups and use beamforming in a group and spatial multiplexing between groups. With antenna grouping, we can achieve diversity gain through beamforming and spectral efficiency through spatial multiplexing. In this paper, we review existing criteria and...
Sphere Decoding algorithm has been shown to achieve near Maximum Likelihood (ML) performance with low complexity for MIMO communication systems, but still has higher complexity than other suboptimum detectors. Especially at low SNR, the complexity of sphere decoding algorithm gets much higher. In this paper, sphere decoding algorithms combined with other suboptimum detectors are proposed. Pre-estimated...
Antenna grouping algorithms are hybrids of beamforming and spatial multiplexing. With antenna grouping, we can achieve diversity gain through beamforming, and high spectral efficiency through spatial multiplexing simultaneously. In an IID channel, at a fixed transmission rate, we can get better BER performance by antenna grouping compared with beamforming. But if the channel is ill-conditioned or...
In this paper, we investigate antenna grouping algorithms which are hybrids of beamforming and spatial multiplexing. With antenna grouping, we can achieve diversity gain through beamforming, and high spectral efficiency through spatial multiplexing. We introduce existing criteria and present several new criteria in multiple-input multiple-output antenna grouping system where the number of transmit...
Multiple-input multiple-output (MIMO) systems have the advantage of spectral efficiency in comparison with single-input single-output (SISO) systems. Through this advantage, data throughput can be significantly increased. The VBLAST (vertical Bell Laboratories layered space-time) scheme was proposed as one possible transceiver structure in terms of performance and complexity. Recently a technique...
We propose a practical SVD-based scheduling technique for MIMO broadcast channel. Multiuser diversity is exploited by scheduling transmissions simultaneously to a group of users who have the best instantaneous channel quality. In order to avoid the inter-user interference, we use a transmit preprocessing technique which decomposes the multiuser MIMO downlink channel into multiple parallel independent...
In this paper, we introduce a channel parameter tracking method for adaptive OFDM MMSE channel estimation. Even though the MMSE estimation is one of the most accurate channel estimation methods, it requires several channel information including Doppler frequency, RMS (root mean squared) delay spread, and noise power. To implement the MMSE estimation, tracking of such parameters should be preceded...
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