Rate-compatible Punctured Convolutional Research Articles

On the Design of FSO-Based Satellite Systems Using Incremental Redundancy Hybrid ARQ Protocols With Rate Adaptation

This paper presents a cross-layer design of error-control protocols with rate adaptation for free-space optical (FSO) burst transmission in satellite communication systems. While the prior works mostly focused on the design of error-control protocols for terrestrial-based FSO communications, using either hybrid automatic repeat request (HARQ) based stop-and-wait mechanism or pure sliding window ARQ, we instead propose a design of HARQ-based sliding window mechanism for the high data-rate and long-distance of FSO-based satellite systems. In particular, we model and analyze the performance of low-earth orbit (LEO) satellite-to-ground FSO systems over atmospheric turbulence channels when truncated incremental redundancy (IR) HARQ protocols, which combine the rate-compatible punctured convolutional (RCPC) codes and sliding window ARQ, are employed. For this purpose, the time-varying behavior of atmospheric turbulence channels is first captured by a finite-state Markov chain. Then, the channel model is used to develop the burst loss model to analytically derive the system performance metrics, including throughput, energy efficiency, and average frame delay. The results quantitatively demonstrate the impact of atmospheric turbulence and pointing error on the system performance and support the optimal selection of parameters. Additionally, the effectiveness of the proposed system is numerically confirmed. Monte Carlo simulations are also performed to validate the accuracy of theoretical derivations.

Near-Optimal Cross-Layer Forward Error Correction Using Raptor and RCPC Codes for Prioritized Video Transmission Over Wireless Channels

Cross-layer forward error correction (FEC) aims at utilizing available bandwidth more efficiently, which has been applied to error-prone video transmission over imperfect wireless channels. In this paper we propose a new near-optimal cross-layer FEC scheme in which systematic Raptor codes are used at the application layer and rate compatible punctured convolutional (RCPC) codes are used at the physical layer for H.264/AVC encoded video streaming with channel bandwidth constraints. In the proposed scheme, in order to fully exploit the unequal importance of compressed video data, we assign each source packet a different priority according to its contribution to the reconstructed video quality. We first obtain the transmission parameters, which satisfies the conditions for optimal video transmission, for the optimal cross-layer Raptor-RCPC FEC in the ideal situation through a theoretical analysis, and then we propose a heuristic algorithm searching from the optimal solution point to obtain the transmission parameters, which are near optimal in the practical situation. Computer simulation results show that the proposed scheme can achieve significant performance improvements in both the additive white Gaussian noise and Rayleigh channels compared with the previous work.

Cross-Layer prioritized H.264 video packetization and error protection over noisy channels

Video transmission over wireless channels is affected by channel-induced packet losses. Distortion due to channel errors can be alleviated by applying forward error correction. Aggregating H.264/AVC slices to form video packets with sizes adapted to their importance can also improve transmission reliability. Larger packets are more likely to be in error but smaller packets require more overhead. We present a cross-layer dynamic programming (DP) approach to minimize the expected received video distortion by jointly addressing the priority-adaptive packet formation at the application layer and rate compatible punctured convolutional (RCPC) code rate allocation at the physical layer for prioritized slices of each group of pictures (GOP). Some low priority slices are also discarded to improve protection to more important slices and meet the channel bit-rate limitations. We propose two schemes. Our first scheme carries out joint optimization for all slices of a GOP at a time. The second scheme extends our cross-layer DP-based approach to slices of each frame by predicting the expected channel bit budget per frame for live streaming. The prediction uses a generalized linear model developed over the cumulative mean squared error per frame, channel SNR, and normalized compressed frame bit budget. The parameters are determined over a video dataset that spans high, medium and low motion complexity. The predicted frame bit budget is used to derive the packet sizes and corresponding RCPC code rates for live transmission using our DP-based approach. Simulation results show that both proposed schemes significantly improve the received video quality over contemporary error protection schemes.

Cross-Layer Forward Error Correction Scheme Using Raptor and RCPC Codes for Prioritized Video Transmission Over Wireless Channels

The unequal error protection (UEP) has shown promising results for transmitting video over error-prone wireless channels. In this paper, we investigate the cross-layer design of forward error correction (FEC) schemes by using the UEP Raptor codes at the application layer (AL) and UEP rate compatible punctured convolutional (RCPC) codes at physical layer (PHY) for prioritized video packets. The video packets are prioritized based on their contribution to the received video quality. A genetic algorithm (GA)-based optimization algorithm is proposed to find the optimal parameters for both Raptor and RCPC codes, to minimize the video distortion and maximize the peak signal-to-noise-ratio for the given video bit rates and channel constraints (i.e., SNR and available bandwidth). We evaluate the performance of four combinations of the UEP schemes for H.264/AVC encoded video sequences over the AWGN and Rayleigh fading channels and show the superiority of the optimized cross-layer UEP FEC scheme. For Rayleigh fading channel, the proposed cross-layer optimization uses two different time-scales at AL and PHY which allows PHY to adapt faster to the changing channel quality.

Throughput and Energy Efficiency of a Cooperative Hybrid ARQ Protocol for Underwater Acoustic Sensor Networks

Due to its efficiency, reliability and better channel and resource utilization, cooperative transmission technologies have been attractive options in underwater as well as terrestrial sensor networks. Their performance can be further improved if merged with forward error correction (FEC) techniques. In this paper, we propose and analyze a retransmission protocol named Cooperative-Hybrid Automatic Repeat reQuest (C-HARQ) for underwater acoustic sensor networks, which exploits both the reliability of cooperative ARQ (CARQ) and the efficiency of incremental redundancy-hybrid ARQ (IR-HARQ) using rate-compatible punctured convolution (RCPC) codes. Extensive Monte Carlo simulations are performed to investigate the performance of the protocol, in terms of both throughput and energy efficiency. The results clearly reveal the enhancement in performance achieved by the C-HARQ protocol, which outperforms both CARQ and conventional stop and wait ARQ (S&W ARQ). Further, using computer simulations, optimum values of various network parameters are estimated so as to extract the best performance out of the C-HARQ protocol.

A Cross-Layer Unequal Error Protection Scheme for Prioritized H.264 Video using RCPC Codes and Hierarchical QAM

We investigate the rate-compatible punctured convolutional (RCPC) codes concatenated with hierarchical QAM for designing a cross-layer unequal error protection scheme for H.264 coded sequences. We first divide the H.264 encoded video slices into three priority classes based on their relative importance. We investigate the system constraints and propose an optimization formulation to compute the optimal parameters of the proposed system for the given source significance information. An upper bound to the significance-weighted bit error rate in the proposed system is derived as a function of system parameters, including the code rate and geometry of the constellation. An example is given with design rules for H.264 video communications and 3.5-4 dB PSNR improvement over existing RCPC based techniques for AWGN wireless channels is shown through simulations.

JPEG Image Transmission over Rayleigh Fading Channel with Unequal Error Protection

In this paper an image transmission system has been proposed where Joint Photographic Experts Group (JPEG) algorithm is used as an image coder and Rate Compatible Punctured Convolution (RCPC) channel coder is used for transmission of coded image over wireless channels (AWGN and Rayleigh fading). JPEG bit stream is partitioned into DC and AC bit streams. AC bit stream further classified using edge density property of block. Priorities based Unequal error Protection (UEP) applied to bit stream. Distortion analysis (MSE) is given for proposed image transmission scheme. The simulation results shows reduction in distortion compared to conventional Equal Error Protection (EEP). This proposed algorithm can be applied for low frequency as well as high frequency images. General Terms Image Coding and transmission through wireless channel

Improving RCPC Codes in Rate-Adaptive Optical Wireless Communications Systems

In this paper, we analyse the performance of rate-compatible punctured convolutional (RCPC) codes for wireless optical communications systems. For these environments, a novel hybrid RCPC coding scheme with a modified puncturing matrix is proposed based on the insertion of variable silence periods. This transmission technique achieves better bit-error rate results than conventional RCPC and convolutional coding schemes, in agreement to the obtained increase in the peak-to-average optical power ratio.

Impact of Implicit Feedback Channel in Cooperative Relay Networks

In a multi-node network, cooperation among nodes is an effective means to enhance coverage and potentially increase the capacity. For such systems, schemes based on incremental relaying have great potential to improve the spectral efficiency by adapting the transmission to time varying channel conditions. The performance enhancement brought about by the presence of relays in such incremental relaying based cooperative systems is dependent on the level of cooperation (based on the relay information quality) and on coordination among the nodes. Coordination is achieved through the use of feedback channels, which incurs significant bandwidth penalty and brings down the spectral efficiency. In order to mitigate this, one can exploit an implicit feedback channel available due to broadcast nature of relay transmissions. Instead of using dedicated feedback channels, the implicit feedback channel is used to measure the relay information quality. Based on this information, the transmitter (source/relay) for the additional coded (redundancy) bits is determined. Such a mechanism enhances the reliability as it ensures the availability of correct information at the destination node for decoding. This paper studies the impact of such an implicit feedback channel by employing powerful codes which exhibit inherent incremental redundancy features, such as rate-compatible codes (rate-compatible punctured convolutional (RCPC) codes and punctured low-density parity-check (LDPC) codes) and rateless codes (Luby Transform (LT) codes). Theoretical analyses of the proposed scheme are presented, and supported with results from extensive simulation studies.

An Effective Method of Image Quality Protection Based on ROI Extraction

Direct compression of original map can’t meet users' request on image quality. In order to harmonize image quality and bandwidth of wireless transmission, a protect scheme of UEP (Unequal Error Protection) with JEPG 2000 coder and Channel coding based on RCPC (Rate Compatible Punctured Convolutional) was proposed to improve ROI-based image quality. Firstly, ROI (region-of-interest) was extracted from Saliency Map based on visual attention model. Secondly, ROI and BG (background region) in image which transmitted in wireless channel respectively, were protected by different encoding bit rates and RCPC Code rates. Finally, the PSNR of image was calculated after transmitting in wireless channel using computer simulations. Experimental results show that ROI-based images with high-level protection get a higher quality than image without ROI while not increasing bandwidth.

Coded cooperation using Reed Solomon codes in slow fading channel

The coded cooperative communication technique utilizes single antenna mobiles in a multi-user environment that share their antennas and incorporate channel coding schemes in order to achieve transmit diversity. This letter presents a new coded cooperation system based on Reed Solomon codes. The RS codes are very effective in correcting random symbol errors and random burst errors over fading channels. The new coded cooperation system splits the data into two frames, using a vector arithmetic operation. The performance of the new system as compared to the coded cooperation system that utilizes the Rate-Compatible Punctured Convolutional (RCPC) coded cooperation is significantly superior with improvement for full diversity gain is around 10dB under variety slow fading channel conditions.

Design of RCPC Encoded V-BLAST MIMO System

A Vertical Bell Laboratories Layered Space-Time Multiple-Input Multiple Output (V-BLAST MIMO) enhanced with Unequal Error Protection (UEP) to achieve highly reliable wireless communication is proposed. The UEP scheme is based on Channel State Information (CSI) available at the transmitter whose calculation utilizes Singular Value Decomposition (SVD) of the MIMO matrix channel. Using Rate-Compatible Punctured Convolutional (RCPC), a different code rate is given for each sub-stream of source information, according to its level of transmit power. To analyze the system performance, an analytical BER comprising the performance of V-BLAST MIMO BPSK-modulated signals and the performance of RCPC codes in Rayleigh fading environment is presented. Simulation results show that increasing the code rate can attain a bandwidth efficiency of 33.3% in expense Eb/No, but this penalty is not severe as the high code rate is used in sub-channels with high attenuation level. It is also shown that a system with 2 transmit and 4 receive antennas will have an improved performance within only 1 dB range compared to a system with 2 transmit and 2 receive antennas. The performance of the proposed system is mostly affected by the type of puncturing matrices chosen.

New Table-Switching and Data-Multiplexing Schemes of Rate-Compatible Punctured Convolutional Codes for Unequal Error Protection

In this letter, rate-compatible punctured convolutional (RCPC) codes are further investigated for the application to unequal error protection (UEP). Besides the rate-compatible restriction, we show that puncturing tables should be switched in a special way called soft-switching to guarantee the designed UEP performance. A new data-multiplexing scheme is also proposed for RCPC codes which can achieve similar UEP performance as the conventional scheme but requires no extra zero-padding for frame termination to improve the system throughput.

Cross-Layer Design for Video Transmission over Wireless Rician Slow-Fading Channels Using an Adaptive Multiresolution Modulation and Coding Scheme

We describe a multilayered video transport scheme for wireless channels capable of adapting to channel conditions in order to maximize end-to-end quality of service (QoS). This scheme combines a scalable H.263+ video source coder with unequal error protection (UEP) across layers. The UEP is achieved by employing different channel codes together with a multiresolution modulation approach to transport the different priority layers. Adaptivity to channel conditions is provided through a joint source-channel coding (JSCC) approach which attempts to jointly optimize the source and channel coding rates together with the modulation parameters to obtain the maximum achievable end-to-end QoS for the prevailing channel conditions. In this work, we model the wireless links as slow-fading Rician channel where the channel conditions can be described in terms of the channel signal-to-noise ratio (SNR) and the ratio of specular-to-diffuse energy . The multiresolution modulation/coding scheme consists of binary rate-compatible punctured convolutional (RCPC) codes used together with nonuniform phase-shift keyed (PSK) signaling constellations. Results indicate that this adaptive JSCC scheme employing scalable video encoding together with a multiresolution modulation/coding approach leads to significant improvements in delivered video quality for specified channel conditions. In particular, the approach results in considerably improved graceful degradation properties for decreasing channel SNR.

Optimum Cooperation of the Cooperative Coding Scheme for Frequency Division Half-Duplex Relay Channels

This paper analyzes the effects of the level of cooperation (LOC) on the performance of a practical cooperative coding scheme for frequency division half-duplex relay links in general wireless ad-hoc networks. The end-to-end bit error probability (BEP) and the corresponding optimum LOG minimizing the end-to-end BEP are investigated for specific realizations using a family of rate compatible punctured convolutional (RCPC) codes. This paper shows that the BEP of the cooperative coding scheme depends on the LOC and there exists an optimum LOC for every specific realization. Further, it is shown that more than a certain level of cooperation is required to achieve possible cooperative gains in practical signal-to-noise ratio (SNR) regions, and increasing LOC does not effect much on the BEP performance for sufficiently large LOCs

Performance evaluation of low density parity check codes for Digital Radio Mondiale (DRM) system

In Digital Radio Mondiale (DRM) system, achieving good audio quality becomes a challenge due to its limited band-width of 9 or 10kHz and the very bad fading channels. Therefore, DRM needs highly efficient channel coding schemes. This paper, proposes the schemes which use the Low-Density Parity-Check (LDPC) coded Bit-Interleaved Coded Modulation (BICM) schemes for the implementation of DRM systems. Simulation results show that the proposed system is more efficient than the Rate Compatible Punctured Convolutional (RCPC) coded DRM system on various broadcast channels, and may be recommended as a coding technology for Digital Amplitude Modulation Broadcasting (DAMB) systems of China.

Weight distribution of a class of binary linear block codes formed from RCPC codes

In this paper, we study the weight enumerator and the numerical performance of a class of binary linear block codes formed from a family of rate-compatible punctured convolutional (RCPC) codes. Also, we present useful numerical results for a well-known family of RCPC codes.

Multilayered protection of embedded video bitstreams over binary symmetric and packet erasure channels

This paper presents a multilayered protection of embedded video bitstreams over bit errors and packet erasure channels using Error Resilient and Error Concealment 3-D SPIHT (ERC-SPIHT) algorithm, which is based on the 3-D SPIHT concepts. A robust source coder is created to give error resilience in source level of the codestream. This robustness is achieved by partitioning the wavelet coefficients into many independent sub-bitstreams while maintaining spatio-temporal tree structures. For higher protection against channel noise, we use a product code. In each packet, the concatenation of a rate compatible punctured convolutional (RCPC) code and an error detecting parity check (CRC) code is used. Across the packets, Reed–Solomon codes are used. These steps provide the robust source coder with additional layers of protection against channel noise. Finally, in the decoder side, an error concealment function is performed for the lost blocks. Simulations show that the multilayered protection of 3-D SPIHT outperforms the methods that use single layer protection in terms of average PSNRs and the PSNR ranges, and provides higher average PSNR’s and lower PSNR variances.

Interactive Video Coding and Transmission over Heterogeneous Wired-to-Wireless IP Networks Using an Edge Proxy

Digital video delivered over wired-to-wireless networks is expected to suffer quality degradation from both packet loss and bit errors in the payload. In this paper, the quality degradation due to packet loss and bit errors in the payload are quantitatively evaluated and their effects are assessed. We propose the use of a concatenated forward error correction (FEC) coding scheme employing Reed-Solomon (RS) codes and rate-compatible punctured convolutional (RCPC) codes to protect the video data from packet loss and bit errors, respectively. Furthermore, the performance of a joint source-channel coding (JSCC) approach employing this concatenated FEC coding scheme for video transmission is studied. Finally, we describe an improved end-to-end architecture using an edge proxy in a mobile support station to implement differential error protection for the corresponding channel impairments expected on the two networks. Results indicate that with an appropriate JSCC approach and the use of an edge proxy, FEC-based error-control techniques together with passive error-recovery techniques can significantly improve the effective video throughput and lead to acceptable video delivery quality over time-varying heterogeneous wired-to-wireless IP networks.

Robust video transmission over error-prone channels via error correcting arithmetic codes

We propose arithmetic codes (ACs) with a forbidden symbol as a joint entropy coding and error protection tool for robust video transmission over error-prone channels. In particular, we introduce a MAP decoder of ACs, and apply it to the transmission of 3-D SPIHT coded video and RTP/UDP/IP H.264 video with data partitioning. Experimental results show that the proposed system exhibits several advantages with respect to other schemes, and outperforms rate-compatible punctured convolutional (RCPC) codes in the applications considered.