| 1. |
- Griffiths, Wayne, et al.
(author)
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APP Decoding of Binary Linear Block Codes on Gilbert-Elliott Channels
- 2005
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Conference paper (peer-reviewed)abstract
- In this paper, a mathematical framework for APP decoding of binary linear block codes on the Gilbert-Elliott channel (GEC) is developed. For this purpose, the theory of group representations and finite state machines are combined for deriving a `dual APP' algorithm for the GEC. The presented approach belongs to the class of single-sweep algorithms. As such, complexity benefits of the dual approaches are preserved while additional storage savings are obtained over other single-sweep algorithms. The presented APP decoding technique also takes account of the increasing demand for efficient utilization of bandwidth making higher rate codes more desirable.
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| 2. |
- Holland, Ian, et al.
(author)
-
Soft Combining for Hybrid ARQ
- 2005
-
In: Electronics Letters. - : IEE. - 0013-5194. ; 41:22, s. 1230-1231
-
Journal article (peer-reviewed)abstract
- A soft combining approach utilising symbol-by-symbol maximum a posteriori probability decoding is proposed for hybrid automatic repeat request schemes. In comparison to an existing soft combining approach, significant reductions in post-decoding bit error rate can be obtained without sacrificing the throughput efficiency. This is achieved with the proposed method by accumulating the signal-to-noise ratio at the channel output on each additional retransmission, for use in calculating extrinsic log-likelihood ratios on subsequent decoding attempts.
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| 3. |
- Kusuma, Tubagus Maulana, et al.
(author)
-
On the Development of a Reduced-Reference Perceptual Image Quality Metric
- 2005
-
Conference paper (peer-reviewed)abstract
- User-oriented image quality assessment has be- come a key factor in wireless multimedia commu- nications. In particular, perceptual quality assess- ment methods are required to measure the overall perceived service quality based on the grading given by human subjects. This paper focuses on the de- velopment of a reduced-reference perceptual image quality metric, which can be applied for in-service quality monitoring and link adaptation purposes. In contrast to the conventional image ¯delity metrics such as the peak signal-to-noise ratio (PSNR), the proposed hybrid image quality metric (HIQM) takes the human perception into account. In addition, HIQM does not rely on the availability of the full reference of the original image at the receiver.
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| 4. |
- Kusuma, Tubagus Maulana, et al.
(author)
-
Utilizing Perceptual Image Quality Metrics for Link Adaptation Based on Region of Interest
- 2005
-
Conference paper (peer-reviewed)abstract
- An implicit link adaptation technique based on hybrid automatic repeat request (H-ARQ) and soft-combining is considered for transmission of Joint Photographic Experts Group 2000 (JPEG2000) images over wireless channels. Adaptation is carried out utilizing an objective perceptual image quality metric that takes into account the human perception. Retransmissions focus on the Region of Interest (ROI) part of the JPEG2000 image to efficiently utilize the bandwidth. Numerical results show that the combination of the proposed perceptual image quality metric with link adaptation provides robust link performance while meeting satisfactory quality constraints.
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| 5. |
- Shaheem, Asri, et al.
(author)
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Channel Reliability Metric for Nakagami-m Fading Without Channel State Information
- 2005
-
Conference paper (peer-reviewed)abstract
- An exact channel reliability metric for Nakagami-m fading when no channel state information (CSI) is available at the receiver, is developed. The proposed metric is suitable for combination with iterative decoding schemes to ensure optimum performance. A low complexity cubic approximation to the exact metric, which offers almost identical performance and significantly outperforms the conventional linear approximation, is presented. The numerical results obtained using a single parity check (SPC) block turbo code (BTC), show that the conventional linear approach can result in up to a 27.5dB penalty at BER of 10E-5, compared to the case where perfect CSI is available. On the other hand, the use of the proposed exact reliability metric results in only a 1.1dB performance loss at the same BER.
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| 6. |
- Yatawara, Yeshan, et al.
(author)
-
Unequal Error Protection for ROI Coded Images over Fading Channels
- 2005
-
Conference paper (peer-reviewed)abstract
- Region of interest (ROI) coding is a feature supported by the Joint Photographic Experts Group 2000 (JPEG2000) image compression standard and allows particular regions of interest within an image to be compressed at a higher quality than the rest of the image. In this paper, unequal error protection (UEP) is proposed for ROI coded JPEG2000 images as a technique for providing increased resilience against the effects of transmission errors over a wireless communications channel. The hierarchical nature of an ROI coded JPEG2000 code-stream lends itself to the use of UEP whereby the important bits of the code-stream are protected with a strong code while the less important bits are protected with a weaker code. Simulation results obtained using symbol-by-symbol maximum a posteriori probability (MAP) decoding demonstrate that the use of UEP offers significant gains in terms of the peak signal to noise ratio (PSNR) and the percentage of readable files. Moreover, the use of ROI-based UEP leads to reduced computational complexity at the receiver.
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