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Interference alignment (IA) effectively improves the capacity of interference channel by overlapping the interference and eliminating at the receivers. At present, most algorithms of the distributed interference alignments design precoder and receiver filter at both transmitters and receivers which causes overhead. This paper presents an improved interference alignment based on minimizing projector...
In this paper, considering the problem of performance loss due to limited feedback in multiuser MIMO downlink systems, a novel limited feedback precoding for multiuser MIMO systems based on array preprocessing is proposed. The maximum SINR criteria is used for selecting optimal codeword from the Grassmannian codebook and perturbation codeword at the receiving, and feedback the Grassmannian precoding...
This paper reports a research testbed of real-time ultra-wideband (UWB) multiple-input multiple-output (MIMO) radio. In the receiver design, the UWB MIMO receiver supports up to eight channels, where each channel is equipped with an analog-to-digital converter (ADC) with 8-bit resolution and sampling rate up to 3 Giga samples per second (Gsps). The transmitter is able to transmit two independent arbitrary...
In this paper the problem of synchronization of data blocks between the transmitter and receiver is discussed, and a solution is described for blind synchronization by using a blind channel estimator. In earlier work, a blind wideband channel estimation algorithm for multipath channels was introduced, which is based on the second order statistics of the received signals. For that blind equalization...
Not only the minimum Euclidean distance but also the number of neighbors providing the dmin in the received constellation has an important role in reducing the error probability when Maximum Likelihood detection is considered. Assuming that the channel-state-information is available at the transmitter, a new precoder in which the rotation parameter has no influence is proposed for two independent...
The problem of stochastically robust minimum mean square error (MMSE) transceiver design is addressed for multiple-input multiple-output (MIMO) point-to-point channels with different imperfect channel state information (CSI) at the receiver and the transmitter. While the receiver has distribution knowledge of the doubly correlated Gaussian channel that is conditioned on pilot-based training observations...
This paper investigates the effect of nonlinearity on the capacity of MIMO systems and develops a capacity-enhancing MIMO transmission technique suitable for deployments over nonlinear channels. Nonlinearity arises in communication systems in several ways. In this work, we focus on the nonlinearity introduced at the transmitter side by the High Power Amplifier (HPA), the last stage in the communication...
It is well-known that for single-input and single-output (SISO) narrow-band transmission on frequency-flat fading channels, uncoded communication with only receiver channel state information (Rx-CSI) leads to extremely poor reliability performance whereas transmitter CSI (Tx-CSI) allows us approach the reliability of an additive white Gaussian noise (AWGN) channel via power control. In this paper,...
Multiple antenna techniques are used to enhance wireless links and therefore have been studied extensively. Many practical systems differ from ideal schemes which have been discussed in the literature. One example is a system that lacks precise channel information at the transmitter. We evaluate analytically the performance of a multiple input multiple output (MIMO) technique that uses partial channel...
Most contributions on nonlinear Tomlinson-Harashima precoding (THP) assume complete channel state information (CSI) at the transmitter. However, complete CSI is not available in many wireless systems, and the conventional THP is sensitive to channel mismatch. This article investigates the THP design with imperfect CSI at base station (BS) in spatially correlated multiuser multiple-input multiple-output...
The Golden Code is a full-rate full-diversity space-time code, which achieves maximum coding gain for Multiple-Input Multiple-Output (MIMO) systems with two transmit and two receive antennas. Since four information symbols taken from an M-QAM constellation are selected to construct one Golden Code codeword, a maximum likelihood decoder using sphere decoding has the worst-case complexity of O(M4),...
This paper investigates the impact of limited feedback on the uplink of a wireless network with multiple access points. The network adopts universal frequency re-use with each access point serving a set of users using orthogonal signalling. All wireless nodes are multiple-input-multiple-output-capable. Block Diagonalization, a popular technique for interference cancellation, is performed at each transmitter...
The paper presents a simulation model of MIMO-OFDM system made in Matlab Simulink. During the work on the simulation model the transmitter, the receiver and the model of telecommunication channel were developed. Signals generated at the transmitter output are fully compatible with signals described in IEEE 802.11n. Simulations are conducted on a radio frequency, so they can be compared with results...
With the active evolvement of 3GPP long term evolution (LTE) system, advanced multi-user multiple-input multiple-output (MU-MIMO) transmission schemes attract more and more interests in engineering field. However, in order to bring advanced MU-MIMO techniques from theory to practice, there are two major obstacles to overcome, i.e., how to obtain accurate channel state information at the transmitter...
When fast and accurate channel state information (CSI) at the transmitter is available, opportunistic power control (OPC) is an attractive alternative to signal-to-interference-and-noise ratio (SINR) target following approaches, because it maximizes throughput by taking advantage of fast channel variations. On the other hand, in multiple-input multiple-output (MIMO) systems, open loop schemes such...
We study a multi-antenna wiretap channel, where the transmitter does not have perfect knowledge about the channels to the eavesdropper. The transmitter only knows that the logical location of the eavesdropper is drawn from a certain set. We characterize the worst-case secrecy rate in this scenario for given transmit strategies and derive an upper and a lower bound for the worst-case secrecy rate that...
A Gaussian multiple-input single-output (MISO) wiretap channel model is considered, where there exists a transmitter equipped with multiple antennas, a legitimate receiver and an eavesdropper each equipped with a single antenna. We study the problem of finding the optimal input covariance that maximizes the ergodic secrecy rate subject to a power constraint, where the full information on the legitimate...
In this paper, we explore the degrees of freedom (DoF) of the broadcast channel (BC) where the transmitter is equipped with M antennas and there are K receivers, each equipped with N reconfigurable antennas capable of switching among M preset modes. Without any knowledge of the channel coefficient values but only receiver antenna switching modes at the transmitter, we propose an interference alignment...
When channel state information is available at the transmitter, it can be exploited to increase the throughput, or to enhance the performance of a multiple input multiple output (MIMO) system. Beamforming schemes, such as closed loop MIMO and transmit beamforming constitute efficient means to achieve the aforementioned objectives. A significant shortcoming of transmit beamforming schemes is the signaling...
In previous study, the capacity of MIMO-OFDM systems were investigated by supposing that different MIMO subcarrier channels are uncorrelated. It is proven that different MIMO subcarrier channels are correlated even though different MIMO delay spread channels are uncorrelated (see (12)). Hence the previous capacity results shouldn't express accurately the actual capacity. Based on the proposed hybrid-domain...
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