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In this paper, we consider multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) amplify-and-forward relay channels. We analyze the maximum achievable diversity of the coded beamforming scheme in MIMO-OFDM relaying systems, and provide proper code designs and the subcarrier pairing criteria that yield the maximum diversity. The pairwise error probability is analyzed...
Beamforming is one of the key techniques for the multiple-input multiple-output (MIMO) wireless communication systems, which enables the system to achieve higher performance. In this paper, the Grassmann codebooks are employed to quantize channel state information (CSI) in the MIMO downlink for Long Term Evolution (LTE). Further more, a novel beamforming (BF) scheme based on the proposed equivalent...
In order to exploit the full degrees of freedom of multi-antenna multi-user systems, accurate channel state information at the transmitter is needed. We consider a low latency and low complexity design for a closed-loop channel state information feedback scheme, where user terminals feed back their channel state information simultaneously to a multi-antenna base station. The underlying theoretical...
In this paper, two decoders with low decoding complexity for a MIMO system with finite bit feedback channel are proposed. Theoretical analysis on performance and simulations show that the loses of performance comparing to the ML-decoder are acceptable.
Optimal reception in MIMO systems including channel coding, is achieved by jointly performing MIMO detection and channel decoding. Since joint processing is too costly (complexity wise), MIMO and channel decoding have to be performed separately on the expenses of performance. Using iterative reception, it is possible to approach capacity limits. LDPC codes have been used in many standards and seem...
The existing cooperative spatial multiplexing (CSM) schemes for MIMO-CDMA network have four vital problems to hinder CSM's application: exact synchronization among the mobile stations(MSs) and base station (BS), spatial channels' estimation for MSs, space-time coding and decoding for BS and MSs, the implementation complexity of BS and MSs. To solve the problems, a simplified cooperative spatial multiplexing...
This paper addresses distributed precoding design for MIMO interference networks, where multiple MIMO links share the same bandwidth. In our proposed design, the precoding matrix for an individual link is given as the product of two matrices obtained in two sequential steps. In particular, the first matrix is derived by maximizing the desired signal power given the leakage power as a penalty and the...
Sphere decoding (SD) algorithms for MIMO receivers can achieve similar performance to maximum-likelihood detection (MLD) algorithm with lower computational complexity. In general, channel decoding methods can achieve better performance if they are combined with soft-output SD rather than hard-output one. Unfortunately, not all soft-output values can be obtained in SD. Although several constants could...
We consider a precoding method in downlink multiuser multiple-input multiple-output (MIMO) transmission with multiple base station (BS) cooperation where some of the instantaneous channel state information (CSI) is not available at the BSs. The proposed precoding method is based on block diagonalization of the channel matrix. However, since some elements of the channel matrix are unknown, we allow...
Codebook design has been investigated extensively over the past few years for quantized precoding in Multiple-Input Multiple-Output (MIMO) communication system. Grassmannian line packing (GLP) codebook is widely used in industry and literature. Traditional GLP codebook can only show good performance in spatial uncorrelated channel. But the practical channel is with varied spatial characteristic. In...
In this paper, a low-complexity soft-output QRD-M detection algorithm is proposed for high-throughput Multiple-input multiple-output (MIMO) systems. By employing novel expansion and sorting scheme, the proposed algorithm can greatly reduce the numbers of the fundamental operations during the tree search process, especially the comparison operations which play a key role in the QRD-M detector' computational...
The problem of transmitting a common message over a multiple-input multiple-output (MIMO) Gaussian broadcast channel with multiple receivers is well understood in terms of capacity. Nevertheless, existing optimal (capacity-achieving) schemes for this scenario require joint decoding of the multiple streams transmitted, entailing high computational complexity. In this paper, a low-complexity scheme...
Despite recent attempts with compound channel settings, guaranteeing information theoretically secure communication rates with no knowledge of the eavesdropper channel states has been elusive to date. In this work, we address this problem, and consider the worst case scenario where the eavesdropper's channel is arbitrarily varying, and is known only by itself. We show that it is possible to provide...
We investigate the effects of imperfect channel knowledge and feedback in incremental-redundancy automatic-repeat request (INR-ARQ) coding systems over multiple-input multiple-output (MIMO) block-fading channels. We propose an ARQ decoder based on nearest neighbour decoding and evaluate the corresponding achievable rates. We then derive the optimal code diversity assuming that the feedback channel...
In this paper, we proposed a system that combines AMC and MIMO schemes. While conventional AMC system changes only the coding rate and modulation, the proposed AdaptiveMCM system also selects the MIMO scheme (diversity, multiplexing) according to channel condition. Furthermore, by applying pre-coding and antenna subset-selection we not only produce optimal performance but also increase the data rate...
In this paper, XPOL channel model is described at first, and then eigenvector structures in rank1 and rank2 transmissions are analyzed. Finally, codebook structure and a method for XPOL codebook design are proposed. Link level performance is also evaluated.
The MIMO-OFDM Adaptive MCM System changes MIMO scheme, channel coding rate, and modulation scheme, adaptively, according to the channel conditions. And the addition of Pre-coding and Antenna Subset Selection assures a better performance and higher data rate. The MIMO-OFDM Adaptive MCM System achieves a better average throughput performance than a Non Adaptive-MCM system; as SNR increases, the throughput...
This paper reflects the LTE physical layer performance by BLER curves of different number of antennas and adopt transmitting diversity or spatial multiplexing under the same number of antennas. In addition, the next simulation adopts HARQ based on the above, maintaining new BLER curves. The result of this simulator serves to evaluate the OFDM-MIMO LTE Link Level performance in different environments...
We investigate a MIMO double-scattering model with both local and remote scatterers, aiming to investigate the effect of scatterer density on channel performances, such as capacity, correlation, and the condition number of the channel matrix in flat and frequency-selective fading channels. The investigations are carried out in terms of scatterer density. It is shown that in flat fading channels the...
In this paper we analyze the sum rate of zero-forcing (ZF) precoding in MISO broadcast channels with limited feedback, transmit correlation and path loss. Our analysis assumes that the number of transmit antennas M and the number of users K are large, while their ratio remains bounded. By applying recent results from random matrix theory we derive a deterministic equivalent of the signal-to-interference...
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