[Show abstract][Hide abstract] ABSTRACT: This paper investigates optimal transmission of space-time block codes (STBCs) in distributed multiple-input multiple-output (D-MIMO) Rayleigh fading channels. The optimal diversity performance is achieved through transmit power allocation implemented at the receiver based on transmit and receive correlations to minimize the average symbol error rate (SER). Evaluation of SER performance of uncoded STBCs over a generalized distributed antenna (DA) topology is first presented, with exact analytical SER expressions derived for MQAM and MPSK symbols. SER upper bounds are also derived, based on which two criteria for complexity reduced antenna subset selection with sub-optimal power allocation are further proposed, whose performance approaches optimal over correlated D-MIMO channels. Moreover, a novel simplified but close SER approximation scheme is devised to significantly facilitate optimal SER calculation. We continue to thoroughly analyze how the optimal diversity is affected by large scale fading, targeted data rate, antenna correlations and transmit power. Finally, we develop a surprisingly close and useful analogy between open loop STBCs in co-located MIMO and optimal STBCs in D-MIMO with minimum feedback (i.e., n bits for n DAs in Criterion 2 with power allocation scheme 2 which equally allocates power to the selected DAs). Extensive simulation results have been presented to demonstrate the effectiveness of our analysis.
[Show abstract][Hide abstract] ABSTRACT: This letter investigates optimal transmission of orthogonal space-time block codes (OSTBCs) over distributed antennas (DAs) in non-ergodic flat Rayleigh fading channels with transmit antenna correlations. A generalized DA topology is considered, where the DAs are grouped into some geographically dispersed ports within each of which the DAs are co-located. Assuming equal power allocation within each port, the outage probability is derived. We find that minimizing the outage probability only requires the feedback of the eigenvalues of the transmit correlation matrix at the transmitter. Since it is computationally intensive to minimize the outage probability, an antenna subset selection with suboptimal power allocation scheme is proposed, whose effectiveness has been demonstrated by numerical results
Preview · Article · Mar 2007 · IEEE Signal Processing Letters
[Show abstract][Hide abstract] ABSTRACT: Aiming to optimally transmit space-time block codes (STBCs) over distributed antennas (DAs), this paper examines downlink transmit antenna subset selection with power allocation for STBCs in non-ergodic Rayleigh fading channels with receive antenna correlations. Closed-form outage probability is first derived, which is a function of data rate, rate of STBCs, transmit power, large-scale fading (shadowing and path loss), power allocation weights to each DA and receive antenna correlation. However, achieving the optimal power allocation solution is computationally demanding and the use of sub-optimal techniques is necessitated. Assuming feedback of eigenvalues of transmit and receive antenna correlation matrix at the transmitter and accurate channel state information (CSI) at the receiver, an antenna subset selection with sub-optimal power allocation scheme is proposed, whose performance approaches optimal. The effectiveness of this sub-optimal method has been demonstrated by numerical results.
No preview · Article · Sep 2006 · IEICE Transactions on Communications
[Show abstract][Hide abstract] ABSTRACT: High spectral efficiency distributed antenna systems (DAS) require vertical Bell-Labs layered space-time (V-BLAST) like spatial multiplexing schemes. However, unlike normal point-to-point multiple input multiple output (MIMO) channels, DAS channels have different large-scale fadings from different transmit antennas, thus making equal power and rate transmission that is feasible in MIMO channels unrealistic in DAS channels. This paper proposes a novel transmit antenna selection scheme with power and rate allocation. The scheme is based on large-scale fading (shadow fading and path loss) and is suitable for V-BLAST structures with zero-forcing and successive interference cancellation (ZF-SIC) receivers, ensuring balanced average symbol error rate (SER) performance in each layer. On the receiver side, a fixed detection order is used, which is obtained in the transmit antenna selection process. Simulation results show that the proposed scheme gives good performance gains over equal power and rate transmission systems without antenna selection.
[Show abstract][Hide abstract] ABSTRACT: This paper studies downlink transmits antenna selection with power and rate allocation in generalized distributed wireless communication systems (G-DWCS). Based on the large-scale fading statistics (path loss and shadow fading) at the transmitter, antenna selection criteria have been proposed for combined space time block code (STBC) and Vertical Bell-Labs Layered Space Time (V-BLAST) structure, where each layer of V-BLAST is composed of co-located multiple antennas for independent STBC transmission. The sub-optimal antenna set, sub-optimal power and rate allocation are determined to minimize an upper bound on the symbol error rate (SER). At the receiver a fixed detection order is followed which is obtained meanwhile in the antenna selection process at the transmitter. It's verified by Monte Carlo simulation that our proposed antenna selection criteria can judiciously select the optimal antenna set and allocate proper power and rate, and are very suitable for G-DWCS system
[Show abstract][Hide abstract] ABSTRACT: The paper studies the downlink single user average capacity of a generalized distributed wireless communication system (G-DWCS). For equal transmission power, the upper bound and an approximate expression of the average capacity are derived. Transmit power can also be allocated in a water-filling like fashion which may further increase power utilization efficiency. In a random antenna layout, the capacity advantage of G-DWCS over standard cell multiple input multiple output (SC MIMO) systems is analysed. Also, sub-optimum antenna selection algorithms are proposed for maximization of the average capacity. Simulation results verify the capacity analysis and capacity improvement due to antenna selection algorithms.
[Show abstract][Hide abstract] ABSTRACT: In this paper, performance of smart antenna in multipath macrocell environment is studied. The system capacity and coverage of TD-SCDMA systems in the macrocell environment are studied and simulated without/with base station smart antenna which is used for dynamic channel allocation, beam forming and power control. System capacity and coverage of TD-SCDMA systems are found to be enlarged greatly by smart antenna. There exist many tradeoff issues that deserve careful planning between cell coverage, capacity, mobile user's maximum transmit power and number of smart antenna elements. For areas with different mobile user density, smart antennas with different elements are to be implemented to reduce costs.