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The use of hybrid automatic-repeat-request (HARQ) with multi-antenna systems (MIMO) promises high throughput with high reliability in broadband wireless communication systems. One of the combining methods in MIMO-HARQ is by directly optimizing the log-likelihood ratio (LLR) values instead of compensating the multiple signal-to-interference-and noise power ratios (SINRs) as in conventional combining...
Receive beamfoming techniques play an important role in MIMO communications systems as means to mitigate interference and enhance the link quality. Multipoint receive beamforming methods are expected to provide additional gains in systems employing advanced coordinated multipoint processing. Due to its importance, receive beamforming has been studied extensively in the literature. The optimal detection...
This paper considers certain aspects of some well-known multiple-input single-output (MISO) codes. In the first section it is proved how in some special cases the n + 1 MISO channel can be seen as consisting of several parallel MISO channels having less transmit antennas. It is also pointed out that unitary conjugation does not change the diversity-multiplexing tradeoff (DMT) of a code. These simple...
Multiple-input double-output (MIDO) codes are important in future wireless communications, where the portable end-user device is physically small and will typically contain maximum two receive antennas. Especially tempting is the 4×2 channel, where the four transmitters can either be all at one station, or separated between two different stations. Such channels optimally employ rate-two space-time...
We propose a new framework for MIMO decoding based on a recently developed technique for reliably conveying linear equations over wireless channels. Each transmit antenna sends an independent data stream using the same linear code. As a result, any integer combination of the codewords is itself a codeword. Each receive antenna observes a random complex-valued combination of the codewords according...
Combining coding, modulation, transmit and receive diversity, and validly increases the anti-noise performance in fading channels, OSTBC (orthogonal space-time block codes) is a new channel coding technology accompanying with the extensive application of wireless communication. Based on typical channel model of the OSTBC in MIMO (multiple-in, multiple-out) wireless communication channels, a general...
The sphere decoding algorithm for signal transmitted on multiple antennas channel is considered. In this paper, the preprocessing stage is analyzed in order to seek a reduced complexity and some improvements are made to enhance the performance. The computer simulation results show that the improved algorithm by applying Pohst Enumeration with selected initial radius is more efficient than that by...
The QR Decomposition (QRD) of communication channel matrices is a fundamental prerequisite to several detection schemes in Multiple-Input Multiple-Output (MIMO) communication systems. Herein, the main feature of the QRD is to transform the non-causal system into a causal system, where consequently efficient detection algorithms based on the Successive Interference Cancellation (SIC) or Sphere Decoder...
The K × 2 multiple input multiple output (MIMO) X-channel with constant channel coefficients available at all transmitters and receivers is considered. A new alignment scheme, named layered interference alignment, is proposed in which both vector and real interference alignment techniques are exploited together with joint processing at receiver sides. Data streams, having fractional multiplexing gains,...
In mobile multiple-input multiple-output (MIMO) - orthogonal frequency division multiplexing (OFDM) communication systems, inter-carrier interference (ICI) and inter-antenna interference (IAI) are two crucial factors that can significantly affect detection performance. Conventionally, ICI and IAI are handled sequentially by ICI mitigation and MIMO detection. This paper proposes a novel iterative receiver...
The original interference alignment (IA) scheme provides poor sum-rate performance compared to simple orthogonal access schemes such as time-division multiple access (TDMA) in low-to-medium SNR under total power constraint. In this paper, we address this problem by proposing a method of regularizing the IA scheme with a criterion of minimizing the weighted sum of the mean square error (WMSE) function...
We consider the problem of constructing linear precoders for quasi-stationary multiple-input multiple-output channels. Maximum-likelihood detection is assumed and the objective of the precoding is to maximize the minimum Euclidean distance of the signaling. Since the channel remains constant for some time, the precoding is performed spatially as well as across time. As will be shown, the precoder...
User scheduling and multiuser multi-antenna (MU-MIMO) transmission are at the core of high-rate data-oriented downlink schemes foreseen in the next-generation cellular systems (e.g., LTE-Advanced). Scheduling exploits the knowledge of the users' instantaneous achievable coding rates. However, when it is applied independently in each cell, the level of inter-cell interference (ICI) experienced by each...
It is known that MIMO detectors performance is highly influenced by the channel matrix condition number. An efficient way to decrease the channel matrix condition number is the use of Lattice Reduction techniques. In this paper a Lattice-Reduction-Aided (LRA) K-Best detector based on the channel matrix condition number is proposed for improving the performance of conventional K-Best algorithm. This...
Sphere Detection (SD) method has been used as a powerful mean to find Maximum Likelihood (ML)solution to the detection problem of Multiple-Input Multiple-Output (MIMO) channels with lower complexity. This method searches closest lattice point inside a sphere. This paper discusses the effect of initial radius of the sphere on the complexity and performance of SD in different noise variances, constellation...
Motivated from results for the point-to-point block MIMO channels without channel knowledge, we investigate possible communication schemes for the non-coherent two-way relaying channel. We propose one construction where the code is constructed from packings in Grassmann manifolds and evaluate the performance of the coding scheme.
This article at first introduces the development of the channel coding technology driven by the Shannon's theory, and the tendency that the coding and modulation will be combined. Then it elaborates on the channel coding problems under the wireless channel. At last it discusses the development direction of the coding technology, that is, when considering the specific wireless communication environment,...
In this paper, we establish a rate duality between the forward and reverse links of MIMO interference channel, where the reverse links are obtained by exchanging the roles of transmitters and receivers in the forward links, and the corresponding channel matrices are conjugate transpose of the forward channel matrices. Since the capacity region for general interference channel is unknown, we show that...
Space time codes (STC) have been shown to be used well with the Multiple Input Multiple Output (MIMO) channel. The Orthogonal STC (OSTC) family of codes is known to achieve full diversity as well as very simple implementation of the Maximum Likelihood (ML) decoder. However, it was proven that with a complex symbol constellation one cannot achieve a full rate code when the number of transmitting antennas...
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