IEEE Transactions on Communications

The problem of computing the capacity-cost function of channels with feedback and the rate-distortion function of sources with feed-forward is considered. Sufficient conditions are derived on : a) the structure of the cost function for a chosen joint distribution to achieve the optimal feedback capacity-cost function, b) the structure of the distortion function for a chosen joint distribution to a... View full abstract»

We extend the methodology in [1] to flat fading channels. The systematically derived receiver structure corresponds to an iterative solution of the joint maximum likelihood (ML) optimization problem. The heuristically derived BICM with iterative decoding is shown to be the outcome of this joint ML optimization problem. View full abstract»

In this letter we examine the application of space-time block codes (STBC) to offset QPSK (OQPSK). We present the maximum-likelihood (ML) decoder for STBC-OQPSK as well as a simplified decoder. We show through analysis and simulation that the simplified decoder matches the performance of the ML decoder. View full abstract»

In this paper, we compare the battery power efficiencies of various pulse-based modulations widely adopted for their low complexity. Taking into account circuit modules and battery imperfectness, we establish simple closed-form analytical formulas which can be used to conveniently determine the relative preference between arbitrary pulse-based modulation pairs in terms of their actual average batt... View full abstract»

In this paper, we investigate the multiple-access (MA) performance of transmitted reference (TR) ultra-wideband (UWB) systems employing M-ary PPM in multipath environments. Because we assume there is no power control in the network, interfering power levels from users can vary over many 10's of dB. We categorize the interfering users into two groups with respect to power levels. A new method for d... View full abstract»

In this letter we propose linear non-regenerative multicarrier multiple-input multiple-output (MIMO) relay technique that aims to minimize the mean-squared error (MSE) of the signal waveform estimation at the destination. We generalize the existing result on the structure of the optimal relay amplifying matrix by considering the direct source-destination link. To minimize the MSE, a power loading ... View full abstract»

We consider the three-node Gaussian relay channel where the relay observes a noisy version of the interference present in the source--destination link. We investigate three fundamental relaying approaches: linear relaying, memoryless nonlinear relaying, and compress-and-forward (CF). For interference-limited cases, we illustrate that optimized memoryless nonlinear relaying almost achieves the capa... View full abstract»

Resource allocation promises significant benefits in wireless networks. In order to fully reap these benefits, it is important to design efficient resource allocation algorithms. Here, we develop relay power allocation (RPA) algorithms for coherent and noncoherent amplify-and-forward (AF) relay networks. The goal is to maximize the output signal-to-noise ratio under individual as well as aggregate... View full abstract»

It has been widely acknowledged that the aggregate interference at the receiver for various practical communication channels can often deviate markedly from the classical additive white Gaussian noise (AWGN) assumption due to various ambient phenomena. Moreover, the physical nature of the underlying interference generating process in such cases can lead to a bursty behaviour of the interfering sig... View full abstract»

In this paper, new constructions of low trellis complexity convolutional codes are presented. New codes are found by searching into a specific class of time varying convolutional codes, which is shaped by some basic properties and search restrictions. An efficient technique for obtaining minimal trellis modules for the proposed codes is provided. Finally, new low complexity convolutional codes of ... View full abstract»

Bit-interleaved coded modulation (BICM) has been adopted in many systems and standards for spectrally efficient coded transmission. The analytical evaluation of BICM performance parameters, in particular bit-error rate (BER), has received considerable attention in the recent past. In this paper, we derive BER approximations for BICM transmission over general fading channels impaired by Gaussian mi... View full abstract»

We consider the multiple-access relay channel with two source nodes, one relay node and one destination node. For practical simplicity, we consider orthogonal transmission of the source messages and half-duplex relaying. We also assume that the relay is memoryless and is implemented based on a two-to-one deterministic mapping. Our focus is on proposing and investigating such mappings. Essentially,... View full abstract»

The Burrows-Wheeler Transform (BWT) is a block sorting algorithm which has been proven to be useful in compressing text data . More recently, schemes based on the BWT have been proposed for lossless data compression using LDPC and Fountain codes, as well as for joint source-channel coding of sources with memory. In this paper we propose a source-controlled Turbo coding scheme for the transmission ... View full abstract»

We consider two nodes equipped with multiple antennas that intend to communicate i.e. both of which transmit and receive data. We model the responses of the communication channels between these nodes as linear and reciprocal (time invariant or with very slow time variations). In practice, we exploit the closed loop conversation between these nodes and present an efficient algorithm allowing to ada... View full abstract»

Physical layer multicasting in wireless networks has been proposed to efficiently send an identical message to multiple users simultaneously. In this paper, we consider multiple antenna multicasting where the transmitter is equipped with Mt antennas and data is transmitted to K single-antenna users. When the downlink channels are assumed to follow an uncorrelated Rayleigh distribution, ... View full abstract»

An analytical expression is derived for the average output signal-to-interference-plus-noise ratio of optimum combining for a spatially correlated array of antennas in the presence of a single interferer and Rayleigh fading. Using the derived expression and based on an asymptotic analysis of the eigenvalues of dense correlation matrices, the asymptotic performance of optimum combining is evaluated... View full abstract»

Hardware constraints, which motivate receive antenna selection, also require that various antenna elements at the receiver be sounded sequentially to obtain estimates required for selecting the `best' antenna and for coherently demodulating data thereafter. Consequently, the channel state information at different antennas is outdated by different amounts and corrupted by noise. We show that, for t... View full abstract»

In this paper, we link the turbo principle to unconstrained maximum likelihood (ML) sequence detection and joint ML parameter estimation. First, we demonstrate for memoryless channels with complete channel state information how the turbo decoder can be systematically derived starting from the ML sequence detection criterion. In particular, we show that a method to solve the ML sequence detection p... View full abstract»

A system involving the multisymbol noncoherent reception of coded continuous-phase frequency-shift keying is developed, optimized, and analyzed. Unlike coherent systems, the modulation index of the waveform does not need to be rational with a small denominator, and the oscillator only needs to be stable for the duration of a small block of symbols. The achievable performance over AWGN and Rayleigh... View full abstract»

Downlink scheduling schemes are well-known and widely investigated under the assumption that the channel state is perfectly known to the scheduler. In the multiuser MIMO (broadcast) case, downlink scheduling in the presence of non-perfect channel state information (CSI) is only scantly treated. In this paper we provide a general framework that addresses the problem systematically. Also, we illumin... View full abstract»

In this work, we revisit classical packet radio networks with a modern treatment of physical-layer (PHY) procedures, medium-access (MAC) and geographic channel-driven routing protocols. Our network model assumes that nodes are randomly distributed on the plane according to a homogeneous spatial Poisson process, using which we provide a novel representation of interference statistics resulting from... View full abstract»

In our earlier works, we proposed rate adaptive hierarchical modulation-assisted two-best user opportunistic scheduling (TBS) and hybrid two-user scheduling (HTS) schemes. The proposed schemes are innovative in the sense that they include a second user in the transmission opportunistically using hierarchical modulations. As such the frequency of information access of the users increases without an... View full abstract»

This paper proposes a simple shortest-path-based load-balanced Internet-Protocol (IP) routing scheme based on the hose model. The proposed scheme is an extension of the Smart-OSPF (S-OSPF) scheme. The proposed scheme, the same as S-OSPF, splits traffic demand only at source edge nodes and transmits the traffic along the shortest path routes. In S-OSPF, the split ratios are determined for each sour... View full abstract»