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In this paper the impact of exponential correlation model on massive multiple input multiple output (MIMO) channel estimation is analyzed using a large number of antennas in the base station (BS) and a user terminal. We consider pilot-based channel estimation in the UL channel. The Linear minimum mean square error (LMMSE) estimator is used to investigate the effect of correlation factor on the average...
It has been shown in the literature that capacity region of the Gaussian broadcast channels is achieved by dirty paper coding but due to full channel state information requirement and high complexity, its application is limited. Several multiple-input multiple-output (MIMO) techniques have been proposed for the orthogonal frequency-division multiplexing (OFDM) systems. In this paper, we consider a...
In this paper, we investigate the effects of outdated channel state information (CSI) in opportunistic relaying systems on the ergodic capacity. The CSI in the data transmission instant may be different from that used in the relay selection instant due to channel variation. When the CSI in the relay-destination link is outdated, the average signal-to-noise ratio (SNR) and the ergodic capacity of the...
This paper evaluates the impact of using outdated channel estimates in a multiuser Amplify-and-Forward (AF) relay network, under Nakagami-m fading. Both variable gain AF and fixed gain AF schemes are considered. Expressions for the system's outage probability and the average bit error rate (BER) are derived. Since the expressions are barely tractable, we also present approximations for the high signal-to-noise...
This paper evaluates the impact of using outdated channel estimates due to feedback delay for relay selection and signal amplification on the performance of partial relay selection with amplify-and-forward (AF) relays. Both variable and fixed gain AF schemes are considered. Expressions for the system's outage probability and the average bit error rate, and their high signal-to-noise ratio (SNR) approximations...
We study the effect of outdated channel estimation on the outage performance of amplify-and-forward (AF) relay selection, where only one out of the set of available relays is activated. In particular, we derive closed-form expressions for the outage probability of two variations of AF relay selection, namely best relay selection and partial relay selection, when the selection is based upon outdated...
We investigate non-coherent multi-input multi-output (MIMO) signal processing which requires no channel state information (CSI) at either the transmitter or the receiver. With non-coherent codes on Grassmann manifold, a receiver employing generalized likelihood ratio test (GLRT) algorithm offers the maximum-likelihood performance even without CSI. However, the conventional GLRT suffers from a severe...
Cooperative multi-cell transmit strategies typically require full channel state information (CSI) at the base station. Most previous works in this area have assumed that base stations have common knowledge of both data dedicated to all terminals and full or partial CSI of all links. In this paper, a more practical limited-feedback scenario is studied for multi-cell joint beamforming. The proposed...
The focus of this paper is on the precoding and feedback strategies for a radio backhaul link between an access base station (ABS) and the hub base station (HBS) in the presence of mobile stations (MSs). In this paper it is assumed that the access and the backhaul links are simultaneous and use the same frequency band. Two feedback links are exploited at the ABS in order to optimize the communication...
This paper researches the capacity of multiple-input multiple-output (MIMO) channels jointly-correlated spatially on both sides in the low signal-to-noise (SNR) regime. We shall derive two key low SNR metrics: the minimum required Eb/N0 and the wideband slope, assuming two types of channel state information (CSI) at the transmitter. We obtain closed-from solutions of these low SNR parameters for Gaussian...
This paper studies the up-link of a multi-user Multiple-Input Multiple-Output (MIMO) system under a fairly general channel model, subsuming a number of situations of relevant practical interest. Concerning the available prior information, we consider the case of Prior Channel State Information at the Transmitter (PCSIT) wherein only a statistical channel characterization is available before transmission,...
We propose a closed-loop multiple-input multiple-output (MIMO) architecture which incorporates unitary precoding and recursive spatial multiplexing. Both techniques take advantage of a feedback channel in a similar way for the transmission of data at high rates with limited signal processing complexity. Unitary precoding is effective in situations with accurate channel state information (CSI) at the...
In this study, we consider a scheduling algorithm for a limited feedback opportunistic beamforming (OBF). Our proposal is based on making Transmit OBF codebook vectors controlled by a rotation weight (RW)in order to obtain almost a zero correlation between the OBF codebook vectors used for the selected spatial channels. Accordingly, we meet the performance of OBF based on the feedback of the full...
This paper concerns a simple limited feedback scheme taking temporal correlation into account during the feedback design in slow fading environment. In this method, the transmitter and the receiver reuse the past channel state information (CSI) as side information. Feedback, that is designed to leverage the side information, is sent from the receiver to the transmitter using a predetermined update...
MIMO system capacity depends on the assumptions about what channel information is known at the transmitters and receivers; i.e., channel state information (CSI) and/or channel distribution information (CDI). We investigate three simple power allocation strategies for improving the maximum possible signaling rate (ergodic capacity) in MIMO systems with complete CSI at the receiver and periodically...
This paper considers downlink multiantenna communication with base stations that perform cooperative precoding in a distributed fashion. Most previous work in the area has assumed that transmitters have common knowledge of both data symbols of all users and full or partial channel state information (CSI). Herein, we assume that each base station only has local CSI, either instantaneous or statistical...
This paper proposes a practical protocol useful for establishing encryption keys between nodes in a wireless network. The method is designed to enable creation of long keys by extracting the increased randomness inherent in reciprocal time-variant multiple-input multiple-output wireless channels. The presentation provides a strategy for exploiting the degrees of freedom existing in the protocol to...
Block diagonalization (BD) is a low-complexity linear preceding scheme for multiuser MIMO (MU-MIMO) downlink, which can completely eliminate multi-user interference with perfect channel state information (CSI) at the transmitter. Under the assumption of block fading channels, BD with fixed amount of feedback is interference-limited. In this paper, we first introduce a low-complexity CSI feedback scheme,...
In this paper, the effect of the input power constraint on the beamforming optimality range in Gaussian two-input multiple-output (TIMO) channels is explored. The obtained results, using standard Lagrangian formulation, determine explicitly the range of the input SNR for which rank-1 signaling (beamforming) is optimal in TIMO channels for both the common power constraint and the individual power constraint...
We investigate the secrecy capacity of an ergodic fading wiretap channel in which the main channel is correlated with the eavesdropper channel. In this study, the full Channel State Information (CSI) is assumed, and thus the transmitter knows the channel gains of the legitimate receiver and the eavesdropper. By analyzing the resulting secrecy capacity we quantify the loss of the secrecy capacity due...
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