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In this paper, we investigate an incremental opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. In our study, we consider regenerative relaying in which the decision to cooperate is based on a signal-to-noise ratio (SNR) threshold and takes into account the effect of the possible erroneously detected and...
The performance of cooperative diversity with opportunistic beamforming is analyzed in Rayleigh fading channels. Cooperative communication is viewed as a method for increasing diversity gain and reducing end to end path loss. The use of relays can create a virtual antenna array so that it allows users to exploit the advantages of multiple input multiple output (MIMO) techniques. In this paper we show...
In this paper, an efficient Decode-and-Forward (DF) relay selection scheme for interference-limited relaying networks is considered. In contrast to previously reported works, we consider multiple interferences which make the conventional relay selection schemes not suitable for interference-limited networks and propose a new relay selection scheme for DF protocol with multiple interferences. Approximate...
In this paper, we propose an analytical framework on the exact computation of the average capacity of multihop transmission over amplify-and-forward relay fading channels. Our approach relies on the algebraic combination of Mellin and Laplace transforms to obtain exact single integral expressions which can be easily computed by Gauss-Chebyshev Quadrature (GCQ) rule. As such, the derived results are...
Fourth Generation Networks will invariably adopt MIMO-OFDMA techniques, in order to cope with increased data rate demands and improved Quality of Service (QoS) requirements. OFDMA is a popular multiple access candidate, since it facilitates multi-user diversity by enabling two dimensional multiple access, in time and frequency domains. Random Beamforming enables exploitation of spatial multi-user...
Interference mitigation and adaptive multi-user resource allocation are among the most promising technological breakthroughs that should improve capacity of future broadband wireless communications. In a multi-cell scenario, where co-channel interference is the performance limiting factor, discrete-rate resource allocation algorithms, selecting those channels with best Signal-to-Interference and Noise-Ratio...
In this paper, we investigate the outage performance of decode-and-forward (DF) based opportunistic cooperative communications with channel estimation errors at the receivers under Rayleigh fading channels, in which the effect of the direct link has been explicitly evaluated. To be specific, the exact expression of outage probability has been derived for arbitrary values of signal-to-noise ratio (SNR)...
This paper offers the statistical analysis of relay assignment in cooperative Decode-and-Forward (DF) networks based on order statistics. By assuming a set of N independent Rayleigh fading channels, first the channel with r-th biggest SNR is analyzed. The diversity order and average error probability for this channel are calculated. Then it is assumed that there are two clusters of terminals and the...
The exact expressions for symbol error probability and outage probability of randomized distributed space-time codes (RDSTC) under Rayleigh fading are derived. The diversity gain derived in the literature uses the Chernoff bound which may not be achievable in general. Utilizing the exact expression, the achievable diversity gain of RDSTCs is validated. The analytical expressions are verified by Monte-Carlo...
In this paper, we review the literature on physical layer energy-efficient communications. The most relevant and recent works are mainly centered around two frameworks: the pragmatic and the information theoretical approaches. Both of them aim at finding the best transmit and/or receive policies which maximize the number of bits that can be reliably conveyed over the channel per unit of energy consumed...
Multiple-input multiple-output (MIMO) systems employing both maximal-ratio transmission and receive antenna selection (MRT&RAS) are studied in this paper. The examination has been done for independent and identically distributed (i.i.d.) flat Nakagami-m fading channels. Exact bit error rate (BER) expressions for binary phase shift keying (BPSK), differential binary phase shift keying (DBPSK) and...
In distributed detection for wireless sensor networks, multiple access schemes and channel conditions affect the performance of data fusion at a fusion center together with communication constraints (bandwidth and transmission energy). For an efficient channel use, the type-based multiple access (TBMA) has been proposed by Mergen et al. Since the performance of TBMA is not satisfactory for zero-mean...
In this paper, the time-delay estimation problem is studied for multiple-input single-output (MISO) systems. First, a theoretical analysis is carried out by deriving the Cramer-Rao lower bound (CRLB) for time-delay estimation in a MISO system. Then, the maximum likelihood (ML) estimator for the time-delay parameter is obtained, which results in a complex optimization problem in general. In order to...
Network coding in cooperative relaying can improve the performance of both users and provide improved efficiency as compared to the conventional relaying. This paper considers different detection schemes for cooperative relaying with network coding. Analytical upper bounds on the bit error probability are derived and used to assess the performance of the different schemes. The obtained results show...
The paper proposes a network coded cooperation protocol for the uplink transmission of relay assisted cellular networks characterized by non-ideal source - relay links. The proposed protocol employs Reed Solomon codes as network codes in order to improve the Block Error Rate (BLER) and Bit Error Rate (BER) performance over the slow varying fading channels. The paper presents also an algorithm for...
In this paper, serial distributed detection under node failure for wireless sensor networks is studied. All previously suggested distributed detection algorithms for wireless sensor networks assume sensor nodes are completely functional. However, sensor nodes are vulnerable to failure for variety of reasons. Hence, node failure tolerant algorithm design is crucial to provide robustness to system under...
We develop a general model based on random coding bounds to explain and predict the coding performance of various type-I and type-II hybrid automatic repeat request (HARQ) schemes based on the bit-interleaved coded modulation (BICM) in 3GPP HSPA. We explore how the intrinsic properties of BICM interact with various transmitter-side (e.g., whether to use the same bit mapping for retransmission) and...
Orthogonal frequency division multiplexing (OFDM) systems have enjoyed widespread adoption in high data rate wired and wireless networks, due to their ability to efficiently cope with slowly varying dispersive channels. This paper considers the information theoretic secrecy rates that are achievable by an OFDM transmitter/receiver pair in the presence of an eavesdropper that might either use an OFDM...
Spatial diversity techniques are now used in most wireless communications systems to improve robustness to signal fading. On the downlink of cellular systems, low-cost requirements of the user terminal tend to favor transmit diversity over receive diversity, and Alamouti's transmit diversity technique appears today in most wireless communications systems standards. But in terms of the total transmit...
In this paper, performance of joint transmit and receive antenna selection in two hop amplify-and-forward relay system is analyzed over frequency non-selective and slowly Nakagami-m fading channels. In the system, all nodes are equipped with multiple antennas; Transmit Antenna Selection (TAS) is employed at the source and relay for transmission, Selection Combining (SC) is employed at the relay and...
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