Eddy Chiu

Robust Transceiver Design for K-Pairs Quasi-Static MIMO Interference Channels via Semi-Definite Relaxation

In this paper, we propose a robust transceiver design for the K-pair quasi-static MIMO interference channel. Each transmitter is equipped with M antennas, each receiver is equipped with N antennas, and the kth transmitter sends Lk independent data streams to the desired receiver. In the literature, there exist a variety of theoretically promising transceiver designs for the interference channel such as interference alignment-based schemes, which have feasibility and practical limitations. In order to address practical system issues and requirements, we consider a transceiver design that enforces robustness against imperfect channel state information (CSI) as well as fair performance among the users in the interference channel. Specifically, we formulate the transceiver design as an optimization problem to maximize the worst-case signal-to-interference-plus-noise ratio among all users. We devise a low complexity iterative algorithm based on alternative optimization and semi-definite relaxation techniques. Numerical results verify the advantages of incorporating into transceiver design for the interference channel important practical issues such as CSI uncertainty and fairness performance.

Cellular Multiuser Two-Way MIMO AF Relaying via Signal Space Alignment: Minimum Weighted SINR Maximization

In this paper, we consider linear MIMO transceiver design for a cellular two-way amplify-and-forward relaying system consisting of a single multiantenna base station, a single multiantenna relay station, and multiple multiantenna mobile stations (MSs). Due to the two-way transmission, the MSs could suffer from tremendous multiuser interference. We apply an interference management model exploiting signal space alignment and propose a transceiver design algorithm, which allows for alleviating the loss in spectral efficiency due to half-duplex operation and providing flexible performance optimization accounting for each users quality of service priorities. Numerical comparisons to conventional two-way relaying schemes based on bidirectional channel inversion and spatial division multiple access-only processing show that the proposed scheme achieves superior error rate and average data rate performance.

Precoder Design for Multi-Antenna Partial Decode-and-Forward (PDF) Cooperative Systems with Statistical CSIT and MMSE-SIC Receivers

Cooperative communication is an important technology in next generation wireless networks. Aside from conventional amplify-and-forward (AF) and decode-and-forward (DF) protocols, the partial decode-and-forward (PDF) protocol is an alternative relaying scheme that is especially promising for scenarios in which the relay node cannot reliably decode the complete source message. However, there are several important issues to be addressed regarding the application of PDF protocols. In this paper, we propose a PDF protocol and MIMO precoder designs at the source and relay nodes. The precoder designs are adapted based on statistical channel state information for correlated MIMO channels, and matched to practical minimum mean-square-error successive interference cancelation (MMSE-SIC) receivers at the relay and destination nodes. We show that under similar settings, the proposed MIMO precoder design with PDF protocol and MMSE-SIC receivers achieves substantial performance enhancement compared with conventional baselines.

Transmit Precoding Design for Multi-Antenna Multicast Broadcast Services with Limited Feedback

The provision for spectrally efficient multicast broadcast services (MBS) is one of the key functional requirements for next generation wireless communication systems. The challenge inherent to MBS is to ensure that all MBS receivers can be served, and one effective solution to this problem is to employ MIMO multicast transmit precoding. In previous works on MIMO multicast transmit precoding design, the authors proposed algorithms given 1) perfect transmitter-side channel state information (CSIT) or 2) specific channel conditions that facilitate precoder optimization with imperfect CSIT. In this paper, we focus on transmit precoding design for MBS where the CSIT is obtained via codebook based limited feedback. In addition, we derive the asymptotic closed-form expressions for the average minimum receive signal-noise-ratio (SNR) among the MBS receivers and study the order of growth with respect to the number of MBS receivers, the number of feedback bits and the number of transmit antennas.

Robust transceiver design for K-pairs quasi-static MIMO interference channels via semi-definite relaxation

In this paper, we propose a robust transceiver design for the K-pair quasi-static MIMO interference channel. Each transmitter is equipped with M antennas, each receiver is equipped with N antennas, and the kth transmitter sends L k independent data streams to the desired receiver. In the literature, there exist a variety of theoretically promising transceiver designs for the interference channel such as interference alignment-based schemes, which have feasibility and practical limitations. In order to address practical system issues and requirements, we consider a transceiver design that enforces robustness against imperfect channel state information (CSI) as well as fair performance among the users in the interference channel. Specifically, we formulate the transceiver design as an optimization problem to maximize the worst-case signal-to-interference-plus-noise ratio among all users. We devise a low complexity iterative algorithm based on alternative optimization and semi-definite relaxation techniques. Numerical results verify the advantages of incorporating into transceiver design for the interference channel important practical issues such as CSI uncertainty and fairness performance.

Performance of analog feedback in closed-loop transmit diversity systems

This paper is concerned with the efficient transmission of channel state information (CSI) in the uplink, and data in the downlink, of a closed-loop transmit diversity system. Two ideas were explored: 1) the employment of analog CSI feedback whereby estimates of the downlink complex gains were fed back periodically to the base-station at a rate of only 1 analog symbol per estimate per frame, and 2) the use of position dependent modulation (PDM) to counter the signal-to-noise ratio variation across a downlink data frame. Simulation results indicated that as far as the bit-error-rate (BER) is concerned, analog feedback is superior to digital feedback because it does not experience unrecoverable quantization errors in the feedback channel estimates. The simulation also indicated that at a given target BER, PDM can attain a substantially higher throughput than fixed modulation

Linear MIMO transceiver design for cellular multi-user two-way AF relaying

In this paper, we consider linear MIMO transceiver design for a cellular two-way amplify-and-forward relaying system consisting of a single multi-antenna base station, a single multi-antenna relay station, and multiple multi-antenna mobile stations (MSs). Due to the two-way transmission, the MSs could suffer from tremendous multi-user interference. We apply an interference management model exploiting signal space alignment and propose a transceiver design algorithm, which allows for alleviating the loss in spectral efficiency due to half-duplex operation and providing flexible performance optimization accounting for each users quality of service priorities. Numerical comparisons to conventional two-way relaying schemes based on bidirectional channel inversion show that the proposed scheme achieves superior error rate and average data rate performance.

Precoder Design for Correlated Multi-Antenna Cooperative Systems with Partial Decode and Forward Protocol and MMSE-SIC Receivers

Cooperative communication is an important technology in next generation wireless networks. Partial decode-and-forward provides an alternative solution for the conventional amplify-and-forward as well as decode-and-forward relay protocols. However, there are several important issues to be addressed regarding the application of partial decode-and-forward protocol. In this paper, we address the practical issues by proposing a joint MIMO precoder design for the multi-antenna cooperative system with correlated MIMO fading and partial decode-and-forward relay protocol. In addition, the MIMO precoders at both the source and the relay are matched to the MMSE-SIC receivers at the destination. We find that under similar system settings, joint MIMO precoder design with partial decode-and-forward relay protocol and MMSE-SIC receivers achieves substantial performance enhancement and has important practical significance.