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In this paper, we consider the adaptive power allocation in the MIMO cognitive network with limited feedback. It is well known that, with the view of guaranteeing the link quality of primary receiver (PRx), the transmit power of second transmitter (STx) is strictly constrained, resulting in that it is difficult to provides QoS guarantee to second receiver (SRx) in the fading channel. This paper focuses...
A modified sphere decoding (SD) scheme is proposed for multiple-input multiple-output (MIMO) communication systems in this paper. The conventional SD goes from the lower dimension to the higher dimension to examine whether a lattice point lies inside the sphere of some radius, which remains fixed for all dimensions. Since the sphere radius directly affects the search range and thus the complexity,...
In this work we evaluate the performance of multistage blind equalization scheme for time-varying MIMO systems. Equalization of the signals is achieved by minimizing a cost function, which is of a linear combination of the constant modulus algorithm (CMA) and the alphabet-matched algorithm (AMA). This has been previously shown to outperform the conventional CMA equalizer in recovery of non-constant...
In previous works, MIMO beamforming in multiuser wireless systems is typically formulated in two ways: one is minimizing the total transmit power with individual signal-to-interference-plus-noise ratio (SINR) constraints for each user; and the other one is maximizing the minimum SINR among all the users with a total transmission power constraint. However, although the total transmit power is optimized,...
Channel reciprocity is regarded as one of the most important advantages of TDD systems. However, the RF front-ends contribute to the channel experienced, and their TX/RX mismatches might cause reciprocity error, and thus degrade system throughput. Therefore, channel reciprocity calibration is a crucial issue. Among the existing calibration methods, Over-the-air (OTA) calibration is a promising approach...
In this paper, we proposed an effective and unified transmit power allocation (TPA) scheme for the Singular Value Decomposition (SVD)-Assisted multi-user multiple-input multiple-output (MU-MIMO) downlink (DL) and uplink (UL) transmissions in the presence of imperfect channel state information (ICSI). The existing power allocation policies for the SVD-Assisted MU-MIMO system, such as equal power allocation...
In this paper, throughput of cognitive multiple-input multiple-output (MIMO) systems operating under quality-of-service (QoS) constraints is studied. It is assumed that transmission power and the covariance of the input signal vector are varied depending on the sensed activities of primary users in the system. Considering the reliability of the transmission and channel sensing results, a state-transition...
In downlink Multiuser Multiple-Input Multiple-Output (MU-MIMO) systems, the zero-forcing (ZF) transmission is a simple and effective technique for separating users and data streams of each user at the transmitter side, but its performance depends greatly on the accuracy of the available channel state information (CSI) at the transmitter. Due to the existence of the CSI delay and channel estimation...
Multi-cell MIMO technique theoretically promises large improvement in spectral efficiency and fairness in cellular networks and is regarded as the key enabling technique for solving the troublesome issue of inter-cell interference. To evaluate its practical performance in the cellular network, we have implemented the real-time downlink multi-cell MIMO trial system operating over bandwidth of 20 MHz...
We analyze a sub-optimum transmit antenna selection (TAS) scheme in multiple input single output (MISO) systems equipped with I transmit antennas. We keep one antenna fixed and select the best among the remaining N - 1 antennas. We assume spatially independent flat fading channel with perfect channel state information (CSI) at receiver and an ideal feedback link. We use Alamouti transmit diversity...
This paper presents the simulated capacity results that could be achieved when echelon, H-shaped, V -shaped free standing dipoles and printed dipole arrays are used in the MIMO systems. As the configurations of interest, in this paper, have dipoles oriented in different directions, the channel model for multi-polarized antennas is used in the simulations. The polarization change at every scatterer...
We consider the use of Blind Interference Alignment (BIA) in a cellular environment as a means for supporting downlink Multi-User MIMO (MU-MIMO) transmission without the need for channel state information at the transmitter (CSIT). This “CSIT-blind” characteristic of BIA is of particular interest for Frequency Division Duplex (FDD) systems, since it allows one to eliminate overheads and impairments...
The rate balancing problem is considered in the multiple-input single-output (MIMO) broadcast channel with linear transceivers. After introducing relative per-stream rate targets as auxiliary variables, the optimization is performed by a gradient projection algorithm. In addition, the transmit and receive filters are updated and the mean square error matrices are diagonalized in each iteration. Although...
In this paper, two precoding algorithms based on channel orthogonalization have been proposed for multi-user MIMO downlink systems. Unlike other conventional methods, the first scheme obtains the orthonormal basis to achieve the precoding matrix by means of using Schmidt Orthogonalization method. In this way, the co-channel interference can be eliminated to some degree. The second algorithm increases...
One of the main challenges in wireless industrial networks is the delay caused by shared, error-prone and non-deterministic behaviour of wireless communication medium. In this paper, a cross-layer adaptive space-time coding scheme has been proposed for the multiple-input multiple-output (MIMO) based IEEE 802.11 Soft-Real-Time Wireless Industrial Networks. Using this technique, packet delay for real-time...
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...
When the receiver of a multiple-input multiple-output (MIMO) channel does not know the channel state, but only a linear estimate thereof, the rates achieved with (suboptimal) Gaussian codebooks become difficult to compute. However, one can resort to upper and lower bounds known from literature. Extending the ideas of earlier works on the resource allocation (time and energy) between pilot and data...
We consider the Noisy MIMO Interference Channel (IFC) with linear transmitters and receivers and full CSI. The maximization of the Weighted Sum Rate (WSR) or transceiver design for Interference Alignment (IA) lead to cost functions with many local optima. Deterministic annealing is an approach that allows to track the variation of the known solution of one version of the problem into the unknown solution...
Recent works on multi-user transmission techniques have shown that the linear growth of capacity in single user MIMO system can be translated to the multi-user MIMO scenario as well. In this paper, we propose a method pursuing performance gain of vector perturbation in multi-user downlink channels. Instead of exploiting the maximum available mobile users for communication, we employ small part of...
In this paper, we propose a precoding algorithm called flexible coordinated beamforming for the MIMO interference relay channel (IRC-FlexCoBF), where two base stations equipped with multiple antennas transmit to two user terminals simultaneously with the assistance of an amplify-and-forward relay that also has multiple antennas. The case of multiple data stream transmission is considered. The relay...
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