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Communications, IEEE Transactions on

Issue 9 • Date September 2010

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Displaying Results 1 - 25 of 33
  • Table of contents

    Publication Year: 2010 , Page(s): c1 - c4
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  • [Staff list]

    Publication Year: 2010 , Page(s): c2
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  • Adaptive Modulation and Coding Schemes Based on LDPC Codes with Irregular Modulation

    Publication Year: 2010 , Page(s): 2465 - 2470
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (387 KB) |  | HTML iconHTML  

    In this paper we propose an adaptive modulation and coding (AMC) scheme which uses only a single low-density parity-check (LDPC) encoder/decoder with irregular modulation. Two Gray-mapped quadrature-amplitude modulations are employed within a codeword so that the transmission rates of the proposed AMC can be controlled even though the rate of the employed LDPC code is fixed. The rate and degree distribution of the employed LDPC code are selected properly for the proposed scheme. We also optimize the bit-to-symbol mapping for the LDPC code over irregular modulation at each transmission rate. The performance of the proposed scheme is compared with that of the AMC scheme with a dedicated LDPC code at each transmission rate. Numerical results show that the proposed scheme has a performance comparable to that of the AMC scheme with dedicated LDPC codes. View full abstract»

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  • A Note on Error Rates for Nakagami-m Fading Multichannel Reception of Binary and M-ary Signals

    Publication Year: 2010 , Page(s): 2471
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (111 KB) |  | HTML iconHTML  

    A new symbol error probability (SEP) formula for selection combining (SC) with M-ary phase shift keying (MPSK) signals in i.i.d. Nakagami-m fading channels is derived. View full abstract»

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  • Power Correlation Coefficient of a Very General Fading Model in Maximal Ratio Combining

    Publication Year: 2010 , Page(s): 2472 - 2479
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB) |  | HTML iconHTML  

    A very general fading scenario is considered for which exact, closed-form formulas for the correlation coefficient of the instantaneous power at the output of a Maximal Ratio Combining receiver is derived. The model includes the main fading environments as very particular cases. It is valid for both identically and non-identically distributed multipath clusters, and for both stationary and nonstationary environments. Most interestingly, the model allows for an uncountable number of combinations of novel fading scenarios. A further generalization is achieved with the angle as well as the time of arrival of the waves permitted to vary throughout the multipath clusters, as opposed to known models for which these parameters are fixed. Several particular examples illustrate the applicability of the general formulations. View full abstract»

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  • Automatic Modulation Classification Methods for Wireless OFDM Systems in TDD Mode

    Publication Year: 2010 , Page(s): 2480 - 2485
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (241 KB) |  | HTML iconHTML  

    This paper presents a novel automatic modulation classification (AMC) algorithm in wireless time division duplex (TDD) orthogonal frequency division multiplexing (OFDM) systems with adaptive modulation (AM). Based upon the maximum-a-posteriori (MAP) criterion, a classification method for digital quadrature amplitude modulation (QAM) schemes is developed that exploits the channel reciprocity in TDD systems and the receiver knowledge about the overall transmission data rate. The AMC algorithm enables the application of adaptive modulation in wireless OFDM systems without loss in the effective data rate caused by signaling of the bit allocation table (BAT). Numerical results show almost no performance loss in terms of the packet error ratio (PER) compared to the case with perfect knowledge of the modulation schemes if the proposed AMC technique is used. View full abstract»

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  • An Exact Performance Analysis of MRC / OSTBC over Generalized Fading Channels

    Publication Year: 2010 , Page(s): 2486 - 2492
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (265 KB) |  | HTML iconHTML  

    A unified analytical framework for evaluating the performance of maximal ratio combining (MRC) and orthogonal space-time block coding (OSTBC) over generalized fading channels is presented. The basic motivation for developing such a framework pertains to analyzing the distribution of a sum of squared random variables (RVs) belonging to different families of fading distributions. Following a novel analytical approach stemming from the definition of a common moment generating function (MGF) model for these families of distributions, the probability density function (PDF) and the cumulative distribution function (CDF) of a general sum of squared RVs are expressed by simple infinite Gamma series expansions. Based on these expressions, the capacity and error probability of MRC/OSTBC over generalized fading channels is thoroughly studied. The developed theory is used to evaluate the performance of OSTBC for a mixed Nakagami-m/Rice fading model and novel analytical results are presented. The accuracy of the derived expressions is validated by extensive Monte Carlo simulations. View full abstract»

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  • Noncoherent Block-Coded TAPSK and 16QAM Using Linear Component Codes

    Publication Year: 2010 , Page(s): 2493 - 2498
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (279 KB) |  | HTML iconHTML  

    In this paper, we derive minimum noncoherent distances of block-coded TAPSK (twisted amplitude and phase shift keying) and 16QAM (quadrature-amplitude modulation), both using linear component codes. According to the derived distances, noncoherent block-coded TAPSK (NBC-TAPSK) and noncoherent block-coded 16QAM (NBC-16QAM) are proposed. If the block length is very small, NBC-16TAPSK performs best among all noncoherent schemes and NBC-16QAM performs worse due to its small minimum noncoherent distance. However, if the block is not short, NBC-16QAM has the best error performance because the codewords with small noncoherent distances are rare. View full abstract»

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  • A Low Complexity Receiver for Noncoherent Amplify-and-Forward Cooperative Systems

    Publication Year: 2010 , Page(s): 2499 - 2504
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (281 KB) |  | HTML iconHTML  

    A maximum energy selection (MES) receiver scheme is proposed for noncoherent amplify-and-forward (AF) cooperative diversity systems. An expression for the symbol error probability of this system when deployed with M-ary frequency shift keying (FSK) modulation is derived. It is shown that a noncoherent AF system employing the proposed MES scheme achieves full spatial diversity, while requiring neither instantaneous nor statistical channel gain information at the destination, but only knowledge of the average source-relay link signal-to-noise ratio (SNR) at the corresponding relay. The average source-relay link SNR information can be locally obtained at each relay using conventional practical estimation techniques, which in turn allows fully distributed implementation of the proposed scheme. View full abstract»

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  • Global and Fast Receiver Antenna Selection for MIMO Systems

    Publication Year: 2010 , Page(s): 2505 - 2510
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (621 KB) |  | HTML iconHTML  

    For a multiple-input multiple-output (MIMO) system with more antennas at the receiver than the transmitter, selecting the same number of receiver antennas as the number of transmit antennas captures most of the advantages of MIMO capacity performance and reduces the system hardware and computational cost at the same time. In this paper, a fast and global-search receive antenna selection algorithm is proposed for this MIMO array configuration. Different from many existing fast but `local' antenna selection algorithms which obtain the sub-optimal channel submatrix by adding or removing one row per step, our algorithm acquires the near-optimal channel matrix by {directly} and {rapidly} searching the maximum-volume submatrix of the original channel matrix. Due to its "globally searching" property, our antenna selection algorithm leads to a substantial improvement in the capacity optimality for moderate to high SNRs, and obtains almost the same capacity performance as that of the exhaustive-search-based optimal antenna selection algorithm. Furthermore, the computational load and memory requirement for our antenna selection method are still comparable to those of the existing sub-optimal antenna selection methods. Numerical results are provided to verify the validity of the proposed methods. View full abstract»

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  • Enhanced Groupwise Detection with a New Receive Combiner for Spatial Multiplexing MIMO Systems

    Publication Year: 2010 , Page(s): 2511 - 2515
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (255 KB) |  | HTML iconHTML  

    In this letter, we propose a new groupwise receive combiner design for multiple-input multiple-output spatial multiplexing systems. The conventional group detection (GD) suffers from a considerable performance loss since the noise components are not taken into account. The output signal-to-interference-plus-noise ratio (SINR) is defined in each subgroup in order to consider both the desired signal and noise statistics. Adopting the real-valued representation, we provide an optimal receive combiner which maximizes the SINR with a general group size. The simulation results show that the proposed scheme achieves a large performance gain over the conventional GD in coded systems. Also, when combining with near-optimal detection algorithms such as sphere decoder, the proposed GD scheme offers a comparable performance with significant reduced complexity. View full abstract»

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  • Capacity-Approaching Irregular Turbo Codes for the Binary Erasure Channel

    Publication Year: 2010 , Page(s): 2516 - 2524
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (425 KB) |  | HTML iconHTML  

    In this paper, we propose a class of irregular turbo codes that approach the capacity of the binary erasure channel. First, an analytic expression of the erasure probability of punctured recursive systematic convolutional codes is derived. This expression will then be used to study the density evolution of turbo codes over the binary erasure channel, that will allow for the design of capacity-approaching infinite-length irregular turbo codes. Next, a graph-optimal interleaver for finite-length irregular turbo codes is proposed. Finally, simulation results for different coding rates are shown. View full abstract»

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  • Signal Space Diversity Techniques with Fast Decoding Based on MDS Codes

    Publication Year: 2010 , Page(s): 2525 - 2536
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (491 KB) |  | HTML iconHTML  

    In wireless communication systems, signal space diversity techniques are usually adopted to combat channel fading by exploiting time diversity, frequency diversity, spatial diversity or a combination of them. Most existing schemes to achieve signal space diversity are based on linear constellation spreading. In this paper, we propose a novel nonlinear signal space diversity technique based on maximum distance separable (MDS) codes. The new technique provides a design flexibility for almost any number of diversity channels and desired diversity orders. We also propose a simple and suboptimal diversity channel selection (DCS) decoding for our new scheme. DCS decoding can greatly reduce the decoding complexity at a cost of marginal performance loss relative to the optimal detection while keeping the diversity order. Simulation results show that with the same throughput but a lower decoding and implementation complexity, our scheme can have superior performance than the optimal linear spreading schemes over either independent fading or additive white Gaussian noise (AWGN) channels. View full abstract»

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  • Performance Bounds and Distance Spectra of Variable Length Codes in Turbo/Concatenated Systems

    Publication Year: 2010 , Page(s): 2537 - 2548
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (912 KB) |  | HTML iconHTML  

    Variable length codes (VLCs), used in data compression, are very sensitive to error propagation in the presence of noisy channels. Addressing this problem with joint source-channel turbo techniques has been proposed in the literature and looks quite promising. But to date, most code-related conclusions are based on simulations. This paper states and proves several theoretical results about the robustness of prefix VLCs concatenated with linear error correcting codes (ECC), assuming a maximum likelihood decoder. Especially, an approximate and asymptotically tight distance spectrum of the concatenated code (VLC+ECC) is rigorously developed. Together with the union bound, it provides upper bounds on the symbol and frame/packet error rates. View full abstract»

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  • Low SNR Capacity for MIMO Rician and Rayleigh-Product Fading Channels with Single Co-channel Interferer and Noise

    Publication Year: 2010 , Page(s): 2549 - 2560
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (525 KB) |  | HTML iconHTML  

    This paper studies the ergodic capacity of multiple-input multiple-output (MIMO) systems with a single co-channel interferer in the low signal-to-noise-ratio (SNR) regime. Two MIMO models namely Rician and Rayleigh-product channels are investigated. Exact analytical expressions for the minimum energy per information bit, Eb/N0min, and wideband slope, S0, are derived for both channels. Our results show that the minimum energy per information bit is the same for both channels while their wideband slopes differ significantly. Further, the impact of the numbers of transmit and receive antennas, the Rician K factor, the channel mean matrix and the interference-to-noise-ratio (INR) on the capacity, is addressed. Results indicate that interference degrades the capacity by increasing the required minimum energy per information bit and reducing the wideband slope. Simulation results validate our analytical results. View full abstract»

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  • On the Moment-Determinance and Random Mixture of Nakagami-m Variates

    Publication Year: 2010 , Page(s): 2561 - 2575
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (695 KB) |  | HTML iconHTML  

    We study complex-valued Nakagami-m variates, establishing the moment determinance of the envelope, phase and joint envelope-phase Nakagami-m probability density functions (pdf's). Inspired by that result, we then show that Nakagami-m variates with arbitrary fading figure m can be accurately decomposed onto a mixture of Nakagami-m variates with integer or half-integer m, i.e, 2m ∈ ℕ+. The latter has the immediate theoretical implication that results currently known to hold for Nakagami-m channels under the constraint 2m ∈ ℕ+ can accurately be extended to arbitrary m via simple linear decomposition, with weights given by the random mixture probabilities, for which formulas are provided. The latter is illustrated with an example of the application of the random mixture decomposition to the simplification and generalization of bit error rate (BER) expressions for PSK modulation in the Nakagami-m relay channel. For completeness, implications on possible extensions and improvements of existing methods to generate Nakagami-m variates is also briefly discussed in the form of further examples. View full abstract»

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  • Semi-Analytical Performance Prediction Methods for Iterative MMSE-IC Multiuser MIMO Joint Decoding

    Publication Year: 2010 , Page(s): 2576 - 2589
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (737 KB) |  | HTML iconHTML  

    In this paper, two semi-analytical performance prediction methods are proposed and compared for multiuser MIMO transmission over block-fading multipath channels and iterative MMSE successive interference cancellation based joint decoding. In the first method, we develop a completely analytical parameterisation of the whole turbo receiver up to the users' channel decoders. The method which follows the classical framework of extrinsic information transfer charts tracks the evolution of the average mutual information defined at coded bit level and circulating between the multiuser detector and the bank of channel decoders. The modelling of the demapping output in the multiuser detector is based on an explicit calculation of the (conditional) mutual information for each symbol digit in a symbol label under arbitrary (possibly non-uniform) a priori probability distributions on others. Then, shifting in viewpoint and considering user demapping and decoding as a joint process, we present an alternative method which tracks the evolution of the average mutual information defined at symbol level and circulating between the MMSE successive interference based interface and the bank of joint demappers and channel decoders. This allows to avoid the critical issue of parameterising the demapping. Numerical results demonstrate the superiority of the second method for high-order non-linear mapping. View full abstract»

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  • A General Framework for Performance Analysis of Space Shift Keying (SSK) Modulation for MISO Correlated Nakagami-m Fading Channels

    Publication Year: 2010 , Page(s): 2590 - 2603
    Cited by:  Papers (36)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (462 KB) |  | HTML iconHTML  

    In this paper, we offer an accurate framework for analyzing the performance of wireless communication systems adopting the recently proposed Space Shift Keying (SSK) modulation scheme. More specifically, we study the performance of a Nt x 1 MISO (Multiple-Input-Single-Output) system setup with Maximum-Likelihood (ML) detection and full Channel State Information (CSI) at the receiver. The exact Average Bit Error Probability (ABEP) over generically correlated and non-identically distributed Nakagami-m fading channels is computed in closed-form when Nt=2, while very accurate and asymptotically tight upper bounds are proposed to compute the ABEP when Nt > 2. With respect to current literature, our contribution is threefold: i) the ABEP is computed in closed-form without resorting to Monte Carlo numerical simulations, which, besides being computationally intensive, only yield limited insights about the system performance and cannot be exploited for a systematic optimization of it, ii) the framework accounts for arbitrary fading conditions and is not restricted to identically distributed fading channels, thus offering a comprehensive understanding of the performance of SSK modulation over generalized fading channels, and iii) the analytical framework could be readily adapted to study the performance over generalized fading channels with arbitrary fading distributions, since the Nakagami-m distribution is a very flexible fading model, which either includes or can closely approximate several other fading models. Numerical results show that the performance of SSK modulation is significantly affected by the characteristics of fading channels, {e.g.}, channel correlation, fading severity, and power imbalance among the Nt transmit-receive wireless links. Analytical frameworks and theoretical findings are also substantiated via Monte Carlo simulations. View full abstract»

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  • Optimal and Suboptimal Differentially Coherent Reception of MDPSK in Time-Spread WSSUS Channel

    Publication Year: 2010 , Page(s): 2604 - 2610
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (335 KB) |  | HTML iconHTML  

    A model of the wide-sense stationary uncorrelated scattering (WSSUS) channel with time-spread and additive white Gaussian noise is considered. The general expression for the symbol-by-symbol reception algorithm of M-ary differential phase shift keying (MDPSK), which realizes implicit diversity, is obtained. Depending on the type of impulse response receiver filter (demodulator kernel), the partial cases that follow from this expression are considered: optimal demodulator, conventional differentially coherent demodulator, demodulator with iterative kernel and its special cases. Relations for assessing the bit error probability of the considered demodulators in the case when signals are transmitted with binary and quadrature differential phase shift keying without taking into account intersymbol interference are derived. The performance bounds for the optimized binary and quadrature systems are determined. The results of the calculation of the bit error probability are presented. View full abstract»

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  • A New Statistical Model of the Complex Nakagami-m Fading Gain

    Publication Year: 2010 , Page(s): 2611 - 2620
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB) |  | HTML iconHTML  

    The Nakagami-m distribution approximates a Rician distribution for the fading parameter m in the range 1 <; m <; ∞, and approximates a Hoyt or Nakagami-q distribution for m in the range 1/2 ≤ m <; 1, while it becomes a Rayleigh distribution for m=1. A uniformly distributed phase for all m ≥ 1/2 does not satisfy all these requirements. By using the distributions of the real and imaginary parts of complex fading gains having Rician and Hoyt distributed envelopes, we propose in this paper a new statistical model of the complex Nakagam-m fading gain for which the envelope has a Nakagami-m distribution and the phase has a nonuniform distribution. Numerical results show that, for a signal having a Nakagami-m distributed fading envelope, the proposed model closely approximates the distributions of the real and imaginary parts of signals with Rician and Hoyt fading envelopes for 1 <; m <; ∞ and 1/2 ≤ m <; 1, respectively, as well as the distributions of the corresponding phases. View full abstract»

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  • Low-Complexity Soft-Output Decoding with Lattice-Reduction-Aided Detectors

    Publication Year: 2010 , Page(s): 2621 - 2629
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (383 KB) |  | HTML iconHTML  

    Lattice reduction (LR) techniques have been introduced to enhance the performance of linear equalizers by collecting diversity with low complexity for many transmission systems. Although LR-aided linear detectors may collect the same diversity as that collected by the maximum-likelihood (ML) detector, there still exists a performance gap between LR-aided and ML equalizers. One approach to fill this gap is to adopt soft-output detectors. Soft-output detectors enable iterative decoding when error-control codes are employed for a system. In this paper, we propose three LR-aided soft-output detectors with different methods to generate the candidate lists. We compare the performance and complexity of our algorithms with the existing alternatives and show that our methods achieve better performance with lower complexity. The performance-complexity tradeoffs of our proposed algorithms are also studied. Iterative decoders are performed based on these soft-output detectors in the simulations to validate the effectiveness of our algorithms. View full abstract»

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  • Deterministic Linear Combining Receivers for Random Fading Channels

    Publication Year: 2010 , Page(s): 2630 - 2638
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (372 KB) |  | HTML iconHTML  

    In this paper, linear combining receivers with deterministic weights are considered for a communication system employing receive diversity in flat Rician fading. We propose two receiver structures: (1) a modified maximum likelihood (ML) receiver in which detection is performed by maximizing the likelihood function of the combined received signal, (2) a deterministic maximal-ratio combining (MRC) receiver which uses the same structure as that of an MRC receiver but with deterministic weights. The deterministic weight vector is chosen such that it minimizes the union bound on the symbol error probability. Methods of computing this deterministic weight vector are presented. The error performance of the receivers is numerically compared with that of the square-law combining receiver and the equal-gain combining (EGC) receiver (which requires more complex phase estimation rather than using fixed, deterministic weights). Numerical results show that in the case of phase-shift keying, the EGC receiver performs better than the modified ML receiver (which has the same performance as that of the deterministic MRC receiver), but the performance gap decreases with increase of the Rician K-factor. It is also seen that in the case of orthogonal frequency-shift keying, the modified ML and deterministic MRC receivers outperform the square-law combining receiver. View full abstract»

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  • QoS Analysis of a Scheduling Policy for Heterogeneous Users Employing AMC Jointly with ARQ

    Publication Year: 2010 , Page(s): 2639 - 2652
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (790 KB) |  | HTML iconHTML  

    This paper analyzes the quality of service (QoS) of scheduling algorithms for heterogeneous users in multi-user (MU) wireless systems that take advantage from a cross-layer design with both adaptive modulation and coding (AMC) and automatic repeat request (ARQ). By developing a general theoretical framework based on a finite-state Markov chain, we analytically evaluate the average delay, the packet-loss rate (PLR) and the throughput of a scheduling algorithm based on the channel condition, the buffer occupancy, and the number of retransmissions, of users belonging to different service classes. The key assumption of our analysis, i.e., the independence of the stationary states of different users, highly reduces the computational complexity while preserving a sufficient accuracy. To present the proposed analysis, we also suggest an effective scheduling policy suitable for users belonging to different service classes, compliant with the WiMAX standard. The good match between analytical and simulated performance validates our theoretical findings, and enables the proposed approach to be used for cross-layer optimization. View full abstract»

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  • Amplify-and-Forward Two-Way Relay Networks: Error Exponents and Resource Allocation

    Publication Year: 2010 , Page(s): 2653 - 2666
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (736 KB) |  | HTML iconHTML  

    In a two-way relay network, two terminals exchange information over a shared wireless half-duplex channel with the help of a relay. Due to its fundamental and practical importance, there has been an increasing interest in this channel. However, there has been little work that characterizes the fundamental tradeoff between the communication reliability and transmission rate across all signal-to-noise ratios. In this paper, we consider amplify-and-forward (AF) two-way relaying due to its simplicity. We first derive the random coding error exponent for the link in each direction. From the exponent expression, the capacity and cutoff rate for each link are also deduced. We then put forth the notion of bottleneck error exponent, which is the worst exponent decay between the two links, to give us insight into the fundamental tradeoff between the rate pair and information-exchange reliability in the two-way relay network. As applications of the error exponent analysis to design a reliable AF two-way relay network, we present two optimization framework to maximize the bottleneck error exponent, namely: i) the optimal rate allocation under a sum-rate constraint and its closed-form quasi-optimal solution that requires only knowledge of the capacity and cutoff rate of each link; and ii) the optimal power allocation under a total power constraint and perfect global channel state information, which is shown equivalently to a quasi-convex optimization problem. Numerical results verify our analysis and the effectiveness of the optimal rate and power allocations in maximizing the bottleneck error exponent, i.e. the network information-exchange reliability. View full abstract»

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  • A Simple Recruitment Scheme of Multiple Nodes for Cooperative MAC

    Publication Year: 2010 , Page(s): 2667 - 2682
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (789 KB) |  | HTML iconHTML  

    Physical (PHY) layer cooperation in a wireless network allows neighboring nodes to share their communication resources in order to create a virtual antenna array by means of distributed transmission and signal processing. A novel medium access control (MAC) protocol, called CoopMAC, has been recently proposed to integrate cooperation at the PHY layer with the MAC sublayer, thereby achieving substantial throughput and delay performance improvements. CoopMAC capitalizes on the broadcast nature of the wireless channel and rate adaptation, recruiting a single relay on the fly to support the communication of a particular source-destination pair. In this paper, we propose a cross-layer rate-adaptive design that opportunistically combines the recruitment of multiple cooperative nodes and carrier sensing multiple access with collision avoidance. We focus on a single-source single-destination setup, and develop a randomized cooperative framework, which is referred to as randomized CoopMAC (RCoopMAC). Thanks to the randomization of the coding rule, the RCoopMAC approach enables the blind participation of multiple relays at unison relying only on the mean channel state information (CSI) of the potential cooperating nodes, without introducing additional signaling overhead to coordinate the relaying process. The proposed RCoopMAC scheme is not only beneficial in substantially improving the link quality and therefore the sustainable data rates but, thanks to the decentralized and agnostic coding rule, it also allows to effectively recruit multiple relays in a robust fashion, i.e., even when the required mean CSI is partially outdated. View full abstract»

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IEEE Transactions on Communications focuses on all telecommunications including telephone, telegraphy, facsimile, and point-to-point television by electromagnetic propagation.

 

 

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Editor-in-Chief
Robert Schober
University of British Columbia