The throughput performance of cooperative repetition and parallel coding in incremental decode-and-forward is investigated. Four transmission methods are considered: parallel coding with and without distributed space-...
详细信息
The throughput performance of cooperative repetition and parallel coding in incremental decode-and-forward is investigated. Four transmission methods are considered: parallel coding with and without distributed space-time coding (PC-ST and PC, respectively);and repetition coding with and without Chase combining at the destination (RC and SC, respectively). The analysis is based on the mutual information seen at the receiver for each scheme. Exact expressions for the outage probability and throughput for all methods are derived. Both ad-hoc and infra-structured relaying scenarios are investigated. Results show that SC can perform very close to RC, PC and PC-ST in terms of throughput, specially in the case of infra-structured relaying or adequate power and rate allocation. The conclusion is that SC would be a better option in practice, since it requires a simpler receiver than PC-ST, PC, and RC.
Numerous DNA- and RNA-level functions are embedded in protein-coding regions, which constrains their structure, function, and evolution. Accumulating evidence suggests that such additional, overlapping functions occur...
详细信息
Numerous DNA- and RNA-level functions are embedded in protein-coding regions, which constrains their structure, function, and evolution. Accumulating evidence suggests that such additional, overlapping functions occur preferentially in the coding sequences of intrinsically disordered proteins/regions (IDPs/IDRs), especially in those that are newly incorporated and thus have reduced selective pressure. It is the lack of strict structural constraints that makes disordered proteins more tolerant to mutations and thus more permissive to the appearance of overlapping functions within their coding sequences than structured domains. Therefore, IDPs/IDRs are often mosaics of segments fulfilling protein functionalities and intervening regions primarily carrying nucleotide-level functions. The ensuing complexification of gene-regulatory circuits may have contributed to the evolutionary spread of structural disorder in complex eukaryotic organisms.
Single-photon methods are emerging as a key approach to 3D imaging. This paper introduces a two step statistical based approach for real-time image reconstruction applicable to a transmission medium with extreme light...
详细信息
Single-photon methods are emerging as a key approach to 3D imaging. This paper introduces a two step statistical based approach for real-time image reconstruction applicable to a transmission medium with extreme light scattering conditions. The first step is an optional target detection method to select informative pixels which have photons reflected from the target, hence allowing data compression. The second is a reconstruction algorithm that exploits data statistics and multiscale information to deliver clean depth and reflectivity images together with associated uncertainty maps. Both methods involve independent operations that are implemented in parallel on graphics processing units (GPUs), which enables real-time data processing of moving scenes at more than 50 depth frames per second for an image of 128 x 128 pixels. Comparisons with state-of-the-art algorithms on simulated and real underwater data demonstrate the benefit of the proposed framework for target detection, and for fast and robust depth estimation at multiple frames per second.
We propose a novel half-duplex decode-and-forward relaying scheme based on partial repetition coding at the relay. In the proposed scheme, if the relay decodes the received message successfully, it re-encodes the mess...
详细信息
We propose a novel half-duplex decode-and-forward relaying scheme based on partial repetition coding at the relay. In the proposed scheme, if the relay decodes the received message successfully, it re-encodes the message using the same channel code as the one used at the source, but retransmits only a fraction of the codeword. We analyze the proposed scheme and optimize the cooperation level (i.e., the fraction of the message that the relay should transmit). We compare our scheme with conventional repetition in which the relay retransmits the entire decoded message, with parallel coding, and additionally with dynamic decode-and-forward (DDF). We provide a finite-SNR analysis for all the collaborative schemes. The analysis reveals that the proposed partial repetition method can provide a gain of several dB over conventional repetition. It also shows that in general, power allocation is less important provided that one optimally allocates bandwidth. Surprisingly, the proposed scheme is able to achieve the same performance as that of parallel coding for some relay network configurations, but at a much lower complexity.
Real-time watermarking for streaming video (such as VOD service) requires significant amounts of computing resources. To address this issue, we present a scalable watermarking scheme integrated in a parallel MPEG-2 en...
详细信息
Real-time watermarking for streaming video (such as VOD service) requires significant amounts of computing resources. To address this issue, we present a scalable watermarking scheme integrated in a parallel MPEG-2 engine. A content-based block selection algorithm is proposed to efficiently embed the pseudo-random watermark signatures into DCT blocks. Our watermark scheme also provides a robust way to synchronize the watermarked video to the original source at detectors and is very resilient against cumulative and temporal attack. We optimize the parallel watermark engine to achieve real-time watermarking performance. We found that the system throughput could suffer significant degradation when processing high-level MPEG-2 video (such as HDTV) due to inefficient management of memory space. Therefore, we investigated an efficient buffer management scheme consisting of two methods: First we reduced the transmission buffer in slave nodes by frames sharing between frames in the Group-of-Picture (GOP) level. Then we further reduce the buffer space by a dynamic on-demand allocation on the slave side. By solving the memory-shortage bottleneck, the proposed system can support real-time watermarking for multiple high-resolution (up to 1404 x 960) video. Published by Elsevier Ltd.
This paper presents a parallelization methodology for video coding based on the philosophy of hiding as much communications by computation as possible, It models the task/data size, processor cache capacity, and commu...
详细信息
This paper presents a parallelization methodology for video coding based on the philosophy of hiding as much communications by computation as possible, It models the task/data size, processor cache capacity, and communication contention, through a systematic decomposition and scheduling approach. With the aid of Petri-nets and task graphs for representation and analysis, it employs a triple buffering scheme to enable the functions of frame capture, management, and coding to be performed in parallel. The theoretical speedup analysis indicates that this method offers excellent communication hiding, resulting in system efficiency well above 90%. To prove its practicality, a H.261 video encoder has been implemented on a TMS320C80 system using the method. Its performance was measured, from which the speedup and efficiency figures were calculated. The only difference detected between the theoretical and measured data is the program control overhead that has not been accounted for in the theoretical model. Even with this, the measured speedup of the H.261 is 3.67 and 3.76 on four parallel processors (PPs) for QCIF and 352 x 240 video, respectively, which correspond to frame rate of 30.7 and 9.25 frames per second, and system efficiency of 91.8 % and 94 %, respectively. This method is particularly efficient for platforms with small number of parallel processors.
High Efficiency Video coding (HEVC) is the new emerging standard released as a successor to H.264/AVC. It aims to improve the encoding performance by saving 50% of the bitrate with the same visual quality. This encodi...
详细信息
ISBN:
(纸本)9781728118208
High Efficiency Video coding (HEVC) is the new emerging standard released as a successor to H.264/AVC. It aims to improve the encoding performance by saving 50% of the bitrate with the same visual quality. This encoding performance makes it more suitable for high definition video applications and could be the next embedded video codec on the majority of multimedia devices. However, this performance is coupled with tremendous computational complexity which makes it very hard to achieve a real-time video encoding with classic embedded processor architectures. Consequently, multicore technology of programmable processors offers a very promising solution to overcome this complexity. In this context, this paper presents a parallel implementation of the HEVC encoder All-Intra (AI) configuration on Quad-core ARM-based platform running at 1.7GHz. OpenMP is used as parallel programming paradigm exploiting the Frame Level parallelism technique. Experimental results show that parallel processing using four threads allows saving up to 73% of encoding time and speeds up the encoding process by a factor of 3.77 without any rate distortion in terms of video quality or bitrate.
In order to efficiently transmit video data while satisfying the channel bandwidth and transmission delay constraints, bit rate control of the video encoding process is required. According to ultra-high-definition vid...
详细信息
ISBN:
(纸本)9789811381386;9789811381379
In order to efficiently transmit video data while satisfying the channel bandwidth and transmission delay constraints, bit rate control of the video encoding process is required. According to ultra-high-definition video, traditional coding algorithms have a large amount of caculation and high computational complexity, thus, parallel coding methods such as inter-frame parallel coding and wavefront parallel coding (WPP) are proposed. However, the rate control of parallel coding is a difficult problem, especially the intra-frame rate control under the WPP coding mode, so this paper proposes a bit rate control algorithm within macro-block layer. By contrasting the PSNR, the encoding speed and the VBV (Video Buffer Verifier) buffer condition of the video sequences, the algorithm proposed in this paper has advantages of less computing cost and faster coding speed than the traditional algorithms.
As an important part in the video coding technology, the rate control aims to achieve a smooth output of the code stream and adjust the quality of the video coding under a limited bandwidth. During the parallel coding...
详细信息
ISBN:
(纸本)9781538651957
As an important part in the video coding technology, the rate control aims to achieve a smooth output of the code stream and adjust the quality of the video coding under a limited bandwidth. During the parallel coding framework, the existing rate control algorithm has its limitation, that is, for the I frame, the bit prediction error is large. This drawback will lead to the result that the quality of the video coding cannot be guaranteed. Since back propagation(BP) neural network shows better performance on approximating complex nonlinear relationship and possessing the advantages of high fault tolerance, strong self-learning ability and controllable prediction error, we propose a new rate control algorithm based on BP neural network for parallel coding framework in this paper. Experimental results demonstrate that the frame-level bit prediction error based on BP neural network is smaller and more stable than the traditional method, which verifies the accuracy and feasibility of this method.
In indoor optical channels, intersymbol interference (ISI) due to the multipath propagation prevents high data rate transmission. In this paper, a new Optical Multi-Wavelength PPM (Pulse Position Modulation) has been ...
详细信息
ISBN:
(纸本)0780338715
In indoor optical channels, intersymbol interference (ISI) due to the multipath propagation prevents high data rate transmission. In this paper, a new Optical Multi-Wavelength PPM (Pulse Position Modulation) has been investigated for improving the quality of transmission. In this strategy, parallel transmission is accomplished which lowers the data rate per channel and thus reduces the effect of ISI. Furthermore, this strategy also implements parallel coding technique in the predetermined parallel branches. This parallel coding corrects errors without changing the system data rate. The simulation results show that a combination of these methods can achieve high quality transmission without reduction of the total data rate.
暂无评论