The Experts below are selected from a list of 2847 Experts worldwide ranked by ideXlab platform
Khalid Sayood - One of the best experts on this subject based on the ideXlab platform.
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joint Source channel coding for variable length codes
IEEE Transactions on Communications, 2000Co-Authors: Khalid Sayood, Hasan H. Otu, N DemirAbstract:When using entropy coding over a noisy channel, it is customary to protect the highly vulnerable bitstream with an error correcting code. In this paper, we propose a technique which utilizes the residual redundancy at the output of the Source Coder to provide error protection for entropy coded systems.
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a joint Source channel Coder with block constraints
IEEE Transactions on Communications, 1999Co-Authors: Hasan H. Otu, Khalid SayoodAbstract:The assumptions made about the Source during Source Coder design result in a residual redundancy at the output of the Source Coder. This redundancy can be utilized for error protection without any additional channel coding. Joint Source/channel Coders obtained using this idea via maximum a posteriori probability deCoders tend to fail at low probability of error. In this paper, we propose a modification of the standard approach which provides protection at low error rates as well.
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joint Source channel coding for variable length codes
Data Compression Conference, 1998Co-Authors: N Demir, Khalid SayoodAbstract:When using entropy coding over a noisy channel it is customary to protect the highly vulnerable bitstream with an error correcting code. In this paper we propose a technique which utilizes the residual redundancy at the output of the Source Coder to provide error protection for entropy coded systems. The proposed approach provides 4-10 dB improvement over the standard approaches at a reduced rate.
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a constrained joint Source channel Coder design
IEEE Journal on Selected Areas in Communications, 1994Co-Authors: Khalid Sayood, Fuling Liu, Jerry D. GibsonAbstract:The design of joint Source/channel Coders in situations where there is residual redundancy at the output of the Source Coder is examined. It has previously been shown that this residual redundancy can be used to provide error protection without a channel Coder. In this paper, this approach is extended to conventional Source Coder/convolutional Coder combinations. A family of nonbinary enCoders is developed which more efficiently use the residual redundancy in the Source Coder output. It is shown through simulation results that the proposed systems outperform conventional Source-channel Coder pairs with gains of greater than 9 dB in the reconstruction SNR at high probability of error. >
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a joint Source channel Coder design
International Conference on Communications, 1993Co-Authors: Khalid Sayood, Fuling Liu, Jerry D. GibsonAbstract:The situation in which there is residual redundancy at the Source Coder output is examined. It has previously been shown that this residual redundancy can be used to provide error correction without a channel enCoder. This approach is extended to conventional Source Coder/convolutional Coder combinations. A design for nonbinary enCoders for this situation is developed. It is shown through simulation results that the proposed systems consistently outperform conventional Source-channel Coder pairs with gains of greater than 10 dB at high probability of error. >
James W Modestino - One of the best experts on this subject based on the ideXlab platform.
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Cross-Layer Design for Video Transmission over Wireless Rician Slow-Fading Channels Using an Adaptive Multiresolution Modulation and Coding Scheme
EURASIP Journal on Advances in Signal Processing, 2007Co-Authors: Yong Pei, James W ModestinoAbstract: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.
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Research Article Cross-Layer Design for Video Transmission over Wireless Rician Slow-Fading Channels Using an Adaptive Multiresolution Modulation and Coding Scheme
2007Co-Authors: Yong Pei, James W ModestinoAbstract: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 ζ 2. 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. Copyright © 2007 Y. Pei and J. W. Modestino. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1
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an adaptive motion based unequal error protection approach for real time video transport over wireless ip networks
IEEE Transactions on Multimedia, 2006Co-Authors: Yong Pei, James W ModestinoAbstract:In this work, we consider the delivery of digital video over future 3G wireless IP networks and we propose a low-complexity adaptive motion-based unequal error protection (UEP) video coding and transmission system which efficiently combines three existing error-resilience techniques by exploiting knowledge of the Source material as well as the channel operating conditions. Given this information, the proposed system can adaptively adjust the operating parameters of the video Source enCoder and the forward error correction (FEC) channel enCoder to maximize the delivered video quality based upon both application-layer video motion estimates and link-layer channel estimates. We demonstrate the efficacy of this approach using the ITU-T H.264 video Source Coder. The results indicate that a significant performance improvement can be achieved with enhanced resilience to inaccurate channel feedback information and with substantially reduced computational complexity compared to competing approaches
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reliable transmission of high quality video over atm networks
IEEE Transactions on Image Processing, 1999Co-Authors: V Parthasarathy, James W Modestino, K S VastolaAbstract:The development of broadband networks has led to the possibility of a wide variety of new and improved service offerings. Packetized video is likely to be one of the most significant high-bandwidth users of such networks. The transmission of variable bit-rate (VBR) video offers the potential promise of constant video quality but is generally accompanied by packet loss which significantly diminishes this potential. We study a class of error recovery schemes employing forward error-control (FEC) coding to recover from such losses. In particular, we show that a hybrid error recovery strategy involving the use of active FEC in tandem with simple passive error concealment schemes offers very robust performance even under high packet losses. We discuss two different methods of applying FEC to alleviate the problem of packet loss. The conventional method of applying FEC generally allocates additional bandwidth for channel coding while maintaining a specified average video coding rate. Such an approach suffers performance degradations at high loads since the bandwidth expansion associated with the use of FEC creates additional congestion that negates the potential benefit in using FEC. In contrast, we study a more efficient FEC application technique in our hybrid approach, which allocates bandwidth for channel coding by throttling the Source Coder rate (i.e., performing higher compression) while maintaining a fixed overall transmission rate. More specifically, we consider the performance of the hybrid approach where the bandwidth to accommodate the FEC overhead is made available by throttling the Source Coder rate sufficiently so that the overall rate after application of FEC is identical to that of the original unprotected system. We obtain the operational rate-distortion characteristics of such a scheme employing selected FEC codes. In doing so, we demonstrate the robust performance achieved by appropriate use of FEC under moderate-to-high packet losses in comparison to the unprotected system.
Yong Pei - One of the best experts on this subject based on the ideXlab platform.
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Cross-Layer Design for Video Transmission over Wireless Rician Slow-Fading Channels Using an Adaptive Multiresolution Modulation and Coding Scheme
EURASIP Journal on Advances in Signal Processing, 2007Co-Authors: Yong Pei, James W ModestinoAbstract: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.
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Research Article Cross-Layer Design for Video Transmission over Wireless Rician Slow-Fading Channels Using an Adaptive Multiresolution Modulation and Coding Scheme
2007Co-Authors: Yong Pei, James W ModestinoAbstract: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 ζ 2. 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. Copyright © 2007 Y. Pei and J. W. Modestino. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1
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an adaptive motion based unequal error protection approach for real time video transport over wireless ip networks
IEEE Transactions on Multimedia, 2006Co-Authors: Yong Pei, James W ModestinoAbstract:In this work, we consider the delivery of digital video over future 3G wireless IP networks and we propose a low-complexity adaptive motion-based unequal error protection (UEP) video coding and transmission system which efficiently combines three existing error-resilience techniques by exploiting knowledge of the Source material as well as the channel operating conditions. Given this information, the proposed system can adaptively adjust the operating parameters of the video Source enCoder and the forward error correction (FEC) channel enCoder to maximize the delivered video quality based upon both application-layer video motion estimates and link-layer channel estimates. We demonstrate the efficacy of this approach using the ITU-T H.264 video Source Coder. The results indicate that a significant performance improvement can be achieved with enhanced resilience to inaccurate channel feedback information and with substantially reduced computational complexity compared to competing approaches
P. Mermelstein - One of the best experts on this subject based on the ideXlab platform.
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Low bit-rate video transmission over fading channels for wireless microcellular systems
IEEE Transactions on Circuits and Systems for Video Technology, 1996Co-Authors: M. Khansari, A. Jalali, Eric Dubois, P. MermelsteinAbstract:We consider the transmission of QCIF resolution (176/spl times/144 pixels) video signals over wireless channels at transmission rates of 64 kb/s and below. The bursty nature of the errors on the wireless channel requires careful control of transmission performance without unduly increasing the overhead for error protection. A dual-rate Source Coder is presented that adaptively selects a coding rate according to the current channel conditions. An automatic repeat request (ARQ) error control technique is employed to retransmit erroneous data-frames. The Source coding rate is selected based on the occupancy level of the ARQ transmission buffer. Error detection followed by retransmission results in less overhead than forward error correction for the same quality. Simulation results are provided for the statistics of the frame-error bursts of the proposed system over code division multiple access (CDMA) channels with average bit error rates of 10/sup -3/ to 10/sup -4/.
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robust low bit rate video transmission over wireless access systems
International Conference on Communications, 1994Co-Authors: M. Khansari, Eric Dubois, A Jalah, P. MermelsteinAbstract:We consider the transmission of QCIF resolution (176/spl times/144 pixels) video signals over wireless channels at transmission rates of 64 kbit/s and below. The bursty nature of the errors on the wireless channel requires careful control of transmission performance without unduly increasing the overhead for error protection. A dual-rate Source Coder is presented that adaptively selects a coding rate according to the current channel conditions. An ARQ (automatic repeat request) error control technique is employed to retransmit erroneous data-frames. The Source coding rate is selected based on the occupancy level of the ARQ transmission buffer. Error detection followed by retransmission results in less overhead than forward error correction for the same quality. Simulation results are provided for the statistics of the frame-error bursts of the proposed system over CDMA channels with average bit error rates of 10/sup -3/ to 10/sup -4/. >
Hasan H. Otu - One of the best experts on this subject based on the ideXlab platform.
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joint Source channel coding for variable length codes
IEEE Transactions on Communications, 2000Co-Authors: Khalid Sayood, Hasan H. Otu, N DemirAbstract:When using entropy coding over a noisy channel, it is customary to protect the highly vulnerable bitstream with an error correcting code. In this paper, we propose a technique which utilizes the residual redundancy at the output of the Source Coder to provide error protection for entropy coded systems.
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a joint Source channel Coder with block constraints
IEEE Transactions on Communications, 1999Co-Authors: Hasan H. Otu, Khalid SayoodAbstract:The assumptions made about the Source during Source Coder design result in a residual redundancy at the output of the Source Coder. This redundancy can be utilized for error protection without any additional channel coding. Joint Source/channel Coders obtained using this idea via maximum a posteriori probability deCoders tend to fail at low probability of error. In this paper, we propose a modification of the standard approach which provides protection at low error rates as well.
