Guard periods are widely used to avoid inter block interference in wireless communication systems. The independent processing of each data block enables computational efficient data estimation, however, the necessary ...
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ISBN:
(纸本)9781424414833
Guard periods are widely used to avoid inter block interference in wireless communication systems. The independent processing of each data block enables computational efficient data estimation, however, the necessary insertion of guard periods produces a transmission overhead and reduces the throughput of the respective transmission system. By using overlapping techniques a block-wise data estimation can be realized without using guard periods. With this modification, either the throughput of the system can be increased or the code rate of the forward error correction code can be reduced. Based on the latter option we will propose two optimized channel coding schemes for the overlapping based system. The first uses a reduced code rate while the second exploits the characteristic error distribution of the overlapping based data estimator. The bit error performance of the resulting transmission systems is finally compared to a common cyclic prefix based transmission system.
Network channel coding (NCC) is a framework under which intermediate router/nodes employ encoding/decoding operations to facilitate an efficient multicast delivery of video. The network usage and video distortion is a...
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ISBN:
(纸本)9781424414369
Network channel coding (NCC) is a framework under which intermediate router/nodes employ encoding/decoding operations to facilitate an efficient multicast delivery of video. The network usage and video distortion is a function of the channel coding rates assigned to nodes in the network. In this paper, we investigate the tradeoff between the total bandwidth usage and a global distortion measure. We propose a dynamic programming based framework to identify the optimal transmission-distortion operating points. The proposed optimal allocation of coding rates is compared with an earlier version of NCC, Network Embedded FEC (NEF), which optimally places codecs of a fixed channel coding rate within the network. The proposed NCC scheme is shown to achieve significantly improved transmission distortion tradeoffs.
The aim of the 3rd generation networks is to combine the multimedia services over Internet and provide them on wireless mobile platforms. The stability, interoperability and robustness offered by MPEG-4 (Moving Pictur...
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ISBN:
(纸本)078039335X
The aim of the 3rd generation networks is to combine the multimedia services over Internet and provide them on wireless mobile platforms. The stability, interoperability and robustness offered by MPEG-4 (Moving Picture Experts Group) make it an ideal solution for mobile networks, and it has been selected by 3GPP (the 3rd Generation Partnership) and 3GPP2 for 3G phones. Burst and random bit errors introduced by fading channels will degrade MPEG-4 streams. Conventional error correcting techniques cannot correct these errors. In this paper, a JSCC (joint source-channel coding) method based on MPEG-4 system and Turbo coder has been proposed. The critical important MPEG-4 streams such as the BIFS (Binary Format for Scenes), OD (Object Descriptors) and IOD (Initial Object Descriptors) streams are transmitted by using TCP (Transmission Control Protocol), and MPEG-4 audio/video ES (Elementary Streams) are transmitted by using UDP (User Datagram Protocol) over 3G channels. Transmission UDP packets is adopted UEP (Unequal Error Protection) Turbo codes according to MPEG-4 audio/video data partitioning. Simulation results show that this method can effectively improve the performance.
This paper proposes a technique to compress the data with equal length code words. A novel source coding technique, multiple label mapping (MLM), is introduced. With MLM it is possible to produce a source code which u...
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ISBN:
(纸本)9781424435746
This paper proposes a technique to compress the data with equal length code words. A novel source coding technique, multiple label mapping (MLM), is introduced. With MLM it is possible to produce a source code which uses equal length code words. Moreover, it is shown that with the MLM technique, it is possible to achieve near limit compression without using variable length coding (VLC). However this requires that the source probability grouping is performed so that after MLM each code word has almost equal appearance probability, and that full a priori feedback is available. Numerical results demonstrate proper operability of the proposed system.
We consider a discrete memoryless joint source-channel setting. In this setting, if a source sequence is reconstructed with distortion below some threshold, we declare a success event. We prove that for any joint sour...
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ISBN:
(纸本)9781467325790
We consider a discrete memoryless joint source-channel setting. In this setting, if a source sequence is reconstructed with distortion below some threshold, we declare a success event. We prove that for any joint source-channel scheme, if this threshold lower (better) than the optimum average distortion, then the success probability approaches zero as the block length increases. Furthermore, we show that the probability has an exponential behavior, and evaluate the optimal exponent. Surprisingly, the best exponential behavior is attainable by a separation-based scheme.
A low delay video transmission over error prone channels with limited bandwidth requires both video and channel coding. A reduction of the distortions added to the video sequence by the video coding and through the ch...
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ISBN:
(纸本)9781728189031
A low delay video transmission over error prone channels with limited bandwidth requires both video and channel coding. A reduction of the distortions added to the video sequence by the video coding and through the channel can be achieved by selecting appropriate configuration parameters for both codecs. In this paper we address this problem from a bit-allocation perspective under the joint source-channel coding approach. We propose an evaluation methodology with a new metric that allows the measurement of the overall distortion of a video communication system. Experimental results, for a system conformed by High Efficiency Video coding (HEVC) and a channel coding with variable coding rate, demonstrate the procedure to evaluate the video communication system and to find a suitable parameter set to reduce the overall distortion of the video at the receiver. For the evaluated system, it was also found a bit allocation strategy between the video and channel codec that reduces the overall distortion. It gives less protection against errors from the channel while reduces the distortion introduced by the video encoder.
This paper considers a joint channel coding and random number generation from the channel output. Specifically, we want to transmit a message to a receiver reliably and at the same time the receiver extracts pure rand...
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This paper considers a joint channel coding and random number generation from the channel output. Specifically, we want to transmit a message to a receiver reliably and at the same time the receiver extracts pure random bits independent of the channel input. We call this problem as the joint channel coding and intrinsic randomness problem. For general channels, we clarify the trade-off between the coding rate and the random bit rate extracted from the channel output by using the achievable rate region, where both the probability of decoding error and the approximation error of random bits asymptotically vanish. We also reveal the achievable rate regions for stationary memoryless channels, additive channels, symmetric channels, and mixed channels.
A novel method for 3D scalable medical image coding with optimized 3D region of interest (3D-RoI) coding was recently proposed. This paper presents one major contribution that enhances this previous work, namely an op...
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ISBN:
(纸本)9780769548562;9781467329866
A novel method for 3D scalable medical image coding with optimized 3D region of interest (3D-RoI) coding was recently proposed. This paper presents one major contribution that enhances this previous work, namely an optimal channel coding method for scalable wireless transmission of 3D regions of interest in 3D medical images. The method is presented in the context of telemedicine, where 3D medical images are first source-coded for storage on a central server and later channel-coded, when request for transmission of a 3D-RoI is initiated. The method is a two-tiered approach: Tier-1 is a source coding scheme, while Tier-2 is a joint source/channel coding scheme where 3D-RoI coding is jointly performed with channel coding. The robustness of the proposed method is evaluated over Rayleigh-fading channels with rate-compatible punctured turbo codes. Comparisons are made with the cases of equal error protection and unequal error protection. Evaluations results on real 3D medical images show a significant improvement in reconstruction quality of the received images, in terms of the average peak signal-to-noise ratio.
This paper compares the impact of using an error detection code and an error correction code for cooperative sequential sensing in cognitive radios. The analyzed system model is a distributed parallel detection networ...
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ISBN:
(纸本)9781467355773
This paper compares the impact of using an error detection code and an error correction code for cooperative sequential sensing in cognitive radios. The analyzed system model is a distributed parallel detection network in which each secondary user (SU) sends a soft decision in the form of quantized local log-likelihood ratio (LLR) to the fusion center (FC), which makes the final decision in a sequential manner. At each SU, the quantized LLRs are converted to bits using Gray mapping. These bits are then channel coded and transmitted using binary phase shift keying (BPSK) to the FC. The reporting-channels between the SUs and the FC may cause errors in the decision statistics. In case of an error detecting code, the decision statistics detected in error are dropped while in case of an error correcting code, the decision statistics are used anyway. The performances of these two schemes are also compared to the case where no channel coding is used. It is shown that even a simple error correcting code gives huge improvement in the performance of sequential sensing while error detecting code may even perform worse than the case where no channel coding scheme is used.
End-to-end deep learning for communication systems, i.e., systems whose encoder and decoder are learned, has attracted significant interest recently, due to its performance which comes close to well-developed classica...
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ISBN:
(纸本)9781538665282
End-to-end deep learning for communication systems, i.e., systems whose encoder and decoder are learned, has attracted significant interest recently, due to its performance which comes close to well-developed classical encoder-decoder designs. However, one of the drawbacks of current learning approaches is that a differentiable channel model is needed for the training of the underlying neural networks. In real-world scenarios, such a channel model is hardly available and often the channel density is not even known at all. Some works, therefore, focus on a generative approach, i.e., generating the channel from samples, or rely on reinforcement learning to circumvent this problem. We present a novel approach which utilizes a recently proposed neural estimator of mutual information. We use this estimator to optimize the encoder for a maximized mutual information, only relying on channel samples. Moreover, we show that our approach achieves the same performance as state-of-the-art end-to-end learning with perfect channel model knowledge.
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