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This paper investigates a network information flow problem for a multiple-input multiple-output (MIMO) Gaussian wireless network with K-users and a single intermediate relay having M antennas. In this network, each user intends to convey a multicast message to all other users while receiving K-1 independent messages from the other users via an intermediate relay. This network information flow is termed...
It is well known that although the conventional sphere decoder (SD) achieves optimal maximum likelihood (ML) performance at a reduced complexity compared to the naive ML detector, the SD computational complexity varies with signal noise ratio (SNR) and is high in the low SNR region. This paper proposes a new idea to overcome these drawback that reduces the complexity significantly at a negligible...
In wireless X networks where all transmitters send the independent messages to all receivers, the theoretical degrees of freedom (DOF) and interference alignment (IA) scheme for its achievability are given by Cadambe and Jafar. However, IA scheme for wireless X network may be infeasible in practice unless the transmitters have the perfect channel information. In addition, if the transmitter with single...
We consider a simple closed-loop spatial multiplexing architecture which can be incorporated into an outer system with off-the-shelf single-input single-output encoders/decoders. Instead of relying on transmitter-side channel state information for matching the layers of the multidimensional signal to the eigenmodes of the multiple-input multiple-output channel through a precoding, the eigenmodes with...
We investigate the capacity bounds for a wireless multicast relay network where two sources simultaneously multicast to two destinations through Gaussian channels with the help of a full-duplex relay node. All the individual channel gains are assumed to be time-invariant and known to every nodes in the network. The transmissions from two sources and from the relay use the same channel resource (i...
In this paper, an efficient closed-loop link adaption scheme consisting of adaptive modulation and coding as well as adaptive precoding is proposed for the 3GPP LTE-A uplink. The uplink envisaged in the LTE-A cellular network will support precoded multi-rank transmission from the users and have base stations with advanced non-linear receivers. Our proposed scheme considers one such advanced receiver,...
MIMO systems with large number (tens) of antennas are getting increased attention. In particular, low-complexity near-optimal detection in such large-MIMO systems has been an interesting topic of recent research. In this context, our new contributions in this paper are two-fold. First, we propose a variant of Markov chain Monte Carlo (MCMC) algorithm which i) alleviates the stalling problem encountered...
The linear dispersion structure is employed to accommodate the dynamic topology of cooperative networks, as well as to achieve higher throughput than conventional space-time codes based on orthogonal designs. Asynchronous Cooperative Liner Dispersion Codes (ACLDC) are applied to achieve full diversity in the presence of asynchronous reception. To achieve a near ML performance with much lower decoding...
We derive a Markov chain Monte Carlo algorithm for data detection in multi-antenna systems. The proposed algorithm is based on the Rao-Blackwellization principle, and is parameterized by a value eta that can be interpreted as a system temperature. We demonstrate by simulations that systems with increased temperature (eta>1) significantly outperform the straightforward choice of eta=1. Due to its...
In this paper, Sphere Decoding (SD) algorithms for Spatial Modulation (SM) are developed to reduce the computational complexity of Maximum--Likelihood (ML--) optimum detectors, which foresee an exhaustive search of the whole search space and have a complexity that linearly increases with the product of number of transmit--antenna, receive--antenna, and size of the modulation scheme. Three SDs specifically...
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