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In this paper, we propose a relay selection method in an amplify-and-forward (AF) scenario considering complete outdated channel state information (CSI) of all links. Differing from the methods in the literatures considering only outdated CSI over the link from the relay to the destination, another type of outdated CSI, i.e., the outdated CSI over the link from the source to the relay, is also considered...
Here a reference light has been used to determine an instantaneous channel fading coefficient to extract the channel state information. Based on the fading coefficient, an optimal optical signal detection scheme is proposed so as to reduce the scintillation effect caused by the atmospheric turbulences. A BER analysis of the detected signal shows an improvement in the performance and the transmission...
This paper evaluates the impact of using outdated channel estimates in a multiuser Amplify-and-Forward (AF) relay network, under Nakagami-m fading.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This paper evaluates the impact of using outdated channel estimates due to feedback delay for relay selection and signal amplification on the performance of partial relay selection with amplify-and-forward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...
In this paper, a Gaussian multiple input multiple output multiple eavesdropper (MIMOME) channel is considered where a transmitter communicates to a receiver in the presence of an eavesdropper. We present a technique for determining the secrecy capacity of the multiple input multiple output (MIMO) channel under Gaussian noise. We transform the degraded MIMOME channel into multiple single input multiple...
In a wireless sensor network with relaying capability, intermediate relay nodes are with limited energy budget. To maximize lifetime of relay nodes, selective relay strategies, requiring full channel state information (CSI), are used to utilizes the best relaying channel. Pilot overhead on relay nodes lifetime is reduced by assuming pilot transmission from destination instead of relay nodes. This...
We consider a multicell random beamforming scheme where a cooperative base station (BS) can simultaneously beamform to its served (local) user via utilizing perfect channel state information and randomly beamform to its neighboring users. The rationale behind this scheme is to curtail channel information feedback in a multicell MIMO system. By sharing antenna degree of freedom and transmit power at...
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...
The availability of Channel State Information (CSI) at the receiver side of a Free Space Optical (FSO) link is required for optimal detection and diversity combining. Consequently, providing instantaneous CSI knowledge introduces challenges to receiver design and an increase in estimation error and bandwidth waste. In this work we investigate two selection-combining diversity schemes and their achieved...
The paper considers a wireless network in which simultaneous communications occur within multiple single antenna source-destination node pairs. An Amplify-and-Forward (AF) relay, equipped with multiple antennas, assists the communication. The relay implements linear beamforming (BF) aiming to minimize the total relay power subject to signal-to-interference ratio (SINR) constraints for each source-destination...
We are concerned with minimizing outage probability in a typical orthogonal frequency division multiplexing (OFDM)-based two-hop relaying network. With the instantaneous channel state information at the receiver of each relay, we drive the optimal relay selection scheme which is jointly with optimum power allocation policies, and can be implemented in a distributed way. Since the power allocation...
Cooperative diversity network has been recently proposed as a way to form virtual antenna arrays that can be used to improve the performance of the wireless network. This paper presents a novel adaptive cooperative diversity scheme with two relays using incremental relaying (TR) protocol. The destination terminal can decide which transmit path will be used according the channel state information....
We study hybrid free-space optical (FSO) and radio-frequency (RF) communications, whereby information is conveyed simultaneously using both optical and RF carriers. We consider the case where both carriers experience scintillation, which is a slow fading process compared to typical data rates. A parallel block-fading channel model is proposed, that incorporates differences in signalling rates, power...
In this paper, we investigate the outage performance of Decode-and-Forward with partial selection relaying in dual-hop cooperative Nakagami-m fading links. The source, based on the unique knowledge of local first hop channel state information, selects the best relay to increase the chances of successful decoding and hence the possibility of cooperation when the direct link is also available. After...
Recent results on cooperative networks have shown great potential in their ability to improve the system performance in the presence of fading channels by using different users' antennas. However, traditional centralized relays selection needs considerable overhead and signaling to exchange the channel state information. In this paper, we propose a simple “ Amplify and Forward” distributed method...
The paper introduces an asymptotic series expansion for the mutual information of Multiple-Input Multiple-Output (MIMO) channels. For low signal to noise ratio (SNR) the first term of expansion approaches mutual information from below. Using the low SNR approximation a new water filling power allocation at the transmitter is derived when the receiver and the transmitter have perfect channel state...
This paper investigates the joint design and optimization of the power control and beamforming codebooks for the single-user multiple-input single-output (MISO) wireless systems with a rate-limited feedback link. The problem is cast in the form of minimizing the outage probability subject to the transmit power constraint and cardinality constraints on the beamforming and power codebooks. We show that...
Cooperative diversity systems rely on using relay nodes to relay copier of transmitted information to the destination such that each copy experiences different channel fading, hence increasing the diversity of the system. In this letter, we proposed a novel distributed cooperative beamforming scheme for decode-and-forward relay networks without channel state information (CSI) feedback. We further...
This work presents a novel adaptive cooperation scheme that takes both the channel state information and residual energy information into account to prolong the network lifetime while meeting the transmission rate requirement of destination. In order to achieve this aim, we will select the relay with the best instantaneous weighted channel conditions by attributing a weight coefficient to each relay...
We consider a broadcast channel (BC) in which the base station is equipped with multiple antennas and each user has a single antenna. We study the design of systems with linear precoders and probabilistically-constrained quality of service (QoS) requirements for each user, in scenarios with imperfect channel state information (CSI) at the transmitter. Each user's QoS is expressed as an upper bound...
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