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In multiple input multiple output (MIMO) systems, predicting performance prior to data transmission remains a difficult problem. This paper proposes an algorithm to predict the average bit error rate (BER) and packet error rate (PER) of a MIMO system, after decoding the error correction code (ECC). Since the algorithm makes no a-priori assumptions about the channel, it is applicable to a wide variety...
To improve the efficiency and simplify the complexity of the relay in cooperative communication systems, an one-bit soft forwarding (SF) scheme is proposed to exploit the erroneously decoded packets that are normally abandoned by the selection decode-and-forward (DF) scheme at the relay, as side information to assist decoding of the direct-link packet at the base station. As this side information...
Iterative decoding of low-density parity-check codes transmitted over noncoherent channels using pilot-symbol- assisted binary phase-shift keying (BPSK) is studied. The log- likelihood ratio of the two values of each transmitted code bit is derived using the joint probability density function of the received signal that carries that bit and a set of reference pilot signals. We establish the relationship...
Coded Cooperation (CC) is a promising user cooperation scheme. In this paper, we propose a novel network- coding-based coded cooperation scheme. When a user decodes its partner's information correctly in the first frame, it transmits the combination of the partner's parity bits and its own parity bits through network coding in the second frame. This is distinct from the classical scheme, where the...
In this paper, we investigate the use of bilingual parsing on parallel corpora to better estimate the rule parameters in a formal syntax-based machine translation system, which are normally estimated from the inaccurate heuristics. We use an expectation-maximization (EM) algorithm to re-estimate the parameters of synchronous context-free grammar (SCFG) rules according to the derivation knowledge from...
In this paper, we propose a novel radius control strategy for sphere decoding referred to as inter search radius control that provides further improvement of the computational complexity with minimal extra cost and negligible performance penalty. The proposed method focuses on the sphere radius control strategy when a candidate lattice point is found. For this purpose, the dynamic radius update strategy...
The problem of designing simple and energy-efficient nonlinear distributed source-channel codes is considered. By demonstrating similarities between this problem and the problem of bandwidth expansion, a structure for source-channel codes is presented and analyzed. Based on this analysis an understanding about desirable properties for such a system is gained and used to produce an explicit source-channel...
In this paper, a new method for logarithmic quantization index modulation (QIM) is proposed. In this regard a logarithmic function is first applied to the host signal. Then the transformed signal is quantized using uniform quantization as conventional QIM to embed watermark data within. Finally using inverse transform the watermarked signal is obtained. The watermark extraction is performed using...
In this paper, we study optimum SNR threshold based partial decode-and-forward (PDF) schemes where relays may choose to forward the demodulated symbols in form of distributed space-time coding (DSTC) or to remain silent according to instantaneous link qualities of the source to relays. Considering the possible error of Maximum likelihood decoding at intermediate relays, we model a general noise in...
In this paper, we consider a cooperative system based on relay selection in a scenario where the available channel state information (CSI) is subject to delays. In order to exploit the selection diversity gains of the system while providing robustness against CSI inaccuracy, we propose a robust relay selection strategy based on a minimum mean square error (MMSE) Bayesian estimator. As shown in the...
A convolutionally encoded noncoherent M-ary Frequency Shift Keying (MFSK) modulation scheme using diversity reception is considered. A novel technique of generating soft information for Soft Decision Decoding (SDD) of noncoherent MFSK is derived assuming various channel models. Furthermore, the convergence behavior of the MFSK receiver is investigated using Extrinsic Information Transfer (EXIT) charts...
Cooperative diversity is a promising technology for future wireless networks. In this paper, we derive the average bit error rate (BER) and outage probability (Pout) for differential equal gain combining (EGC) in cooperative diversity networks. The considered network uses adaptive decode-and-forward (DF) relaying over independent non-identical Nakagami-m fading channels. In adaptive DF relaying among...
In earlier work, Demaret and Iske proposed the scattered data coding (SDC) method for (single-rate) coding of arbitrarily-sampled image data. In this paper, several modifications to the SDC method are proposed in order to remove some limitations of the original scheme, improve coding efficiency, and add a progressive lossy-to-lossless coding capability. Through experimental results, the proposed method...
Our work builds a general visibility model of video packets which is applicable to various types of GOP (group of pictures). The data used for analysis and building the model come from three subjective experiment sets with different encoding and decoding parameters on H.264 and MPEG-2 videos. We consider factors not only within a packet but also across its vicinity to account for possible temporal...
The detection of laughter in conversational interaction presents an important challenge in meeting understanding, important primarily because laughter is predictive of the emotional state of participants. We present evidence which suggests that ignoring unvoiced laughter improves the prediction of emotional involvement in collocated speech, making a case for the distinction between voiced and unvoiced...
This paper proposes codes that achieve the fundamental capacity limits of digital fingerprinting subject to mean-squared distortion constraints on the fingerprint embedder and the colluders. We first show that the traditional method of fingerprint decoding by thresholding correlation statistics falls short of this goal: reliable performance is impossible at code rates greater than some value C1 that...
An iterative detection aided down-link (DL) space division multiple access (SDMA) system is proposed. The base station (BS) requires DL channel state information (CSI) estimated by and fed back from the mobile station (MS) for separating the DL signals to be transmitted to the MSs from the BS. We investigate the achievable system performance subject to finite-accuracy CSI feedback. The achievable...
When channel state information (CSI) is not available to the transmitter, outage events might happen and automatic repeat request (ARQ) is implemented to ensure reliable transmission in such case. In this paper, we consider a three nodes relay system with hybrid relay scheme, where the relay, based on it decoding status, could switch between decode-and-forward (DF) and compress-and-forward (CF) adaptively...
Gaussian mixture model (GMM)-based Kalman predictive coders have been shown to perform better than baseline GMM recursive coders in predictive coding of line spectral frequencies (LSFs) for both clean and packet loss conditions However, these stationary GMM Kalman predictive coders were not specifically designed for operation in packet loss conditions. In this paper, we demonstrate an approach to...
The clipping of log-likelihood ratios (LLRs) in soft demodulators for multiple-input multiple-output (MIMO) systems with bit-interleaved coded modulation (BICM) was recently observed to allow for enormous complexity savings. In this paper we first provide an information-geometric interpretation of LLR clipping as information projection onto a log-convex manifold. Then we study the system capacity...
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