Pub Date : 1996-09-04DOI: 10.1109/WIVC.1996.624633
P. Cherriman, L. Hanzo
The cellular channel capacity of conventional cells is shown to vary dramatically as a function of the distance from the base station. An intelligent 7.3 kBaud adaptive videophone transceiver is contrived, in order to exploit the higher channel capacity of uninterfered cell areas and to satisfy the prevalent system optimisation criteria. The system employed an enhanced H.263-compatible video codec and it was capable of operating over a wide range of operating conditions. The proposed technique has the potential to support videotelephony over existing and future wireless systems using the H.263 video codec.
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Pub Date : 1996-09-04DOI: 10.1109/WIVC.1996.624636
M. Ruf, J. Hagenauer
With the fast growing importance of wireless image communication, the need to deal with fading and other channel distortions arises, in order to enhance the overall throughput and quality of transmitted images. Besides the classical way of combined source and channel coding (Modestino and Daut, 1979) we present a new approach by using source-controlled channel decoding (Hagenauer, 1995) that can be applied either in addition or in conjunction with the above mentioned method. Since there is no optimum source encoder, the generated source data still contains some amount of redundancy (Ruf, 1995). An extension of the well known Viterbi algorithm (Forney, 1973), the a priori soft output Viterbi algorithm (APRI-SOVA), uses the remaining redundancy to improve the error correcting capability. This leads to gains in picture quality of up to 2.2 dB (PSNR) or up to 0.5 dB in channel signal-to-noise ratio (E/sub s//N/sub 0/). Furthermore, the APRI-SOVA allows a more graceful degradation in the case of degrading channel conditions when used for channel decoding instead of conventional Viterbi decoding in image transmission.
随着无线图像通信的重要性日益提高，为了提高传输图像的整体吞吐量和质量，需要处理衰落和其他信道失真。除了经典的信源和信道组合编码(Modestino and Daut, 1979)之外，我们提出了一种新的方法，即使用信源控制的信道解码(Hagenauer, 1995)，这种方法既可以与上述方法一起使用，也可以与上述方法结合使用。由于没有最优的源编码器，生成的源数据仍然包含一定数量的冗余(Ruf, 1995)。作为著名的Viterbi算法(Forney, 1973)的扩展，先验软输出Viterbi算法(aprii - sova)利用剩余冗余来提高纠错能力。这导致图像质量的增益高达2.2 dB (PSNR)或高达0.5 dB的信道信噪比(E/sub //N/sub 0/)。此外，当在图像传输中用于信道解码而不是传统的维特比解码时，在信道条件下降的情况下，aprii - sova允许更优雅的降级。
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Pub Date : 1996-09-04DOI: 10.1109/WIVC.1996.624656
M. Morimoto, M. Okada, S. Komaki
This paper proposes a new mobile image transmission system based on the hierarchical modulation scheme for achieving a high quality and high speed digital image transmission in a band-limited fading channel. The proposed system uses a hierarchical QAM (quadrature amplitude modulation) scheme to give unequal transmission reliability depending on the significance of DCT (discrete cosine transform) based compressed images. Computer simulation results show that the proposed system is an effective high-quality and high-speed image transmission technique in the band-limited fading channel.
{"title":"A hierarchical image transmission system for multimedia mobile communication","authors":"M. Morimoto, M. Okada, S. Komaki","doi":"10.1109/WIVC.1996.624656","DOIUrl":"https://doi.org/10.1109/WIVC.1996.624656","url":null,"abstract":"This paper proposes a new mobile image transmission system based on the hierarchical modulation scheme for achieving a high quality and high speed digital image transmission in a band-limited fading channel. The proposed system uses a hierarchical QAM (quadrature amplitude modulation) scheme to give unequal transmission reliability depending on the significance of DCT (discrete cosine transform) based compressed images. Computer simulation results show that the proposed system is an effective high-quality and high-speed image transmission technique in the band-limited fading channel.","PeriodicalId":422426,"journal":{"name":"Proceedings of First International Workshop on Wireless Image/Video Communications","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129975794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-09-04DOI: 10.1109/WIVC.1996.624641
P. Czerepinski, D. Bull
Morphological segmentation has recognised advantages for video compression, especially at lower bit rates. A two stage approach has traditionally been employed to encode the interframe data produced by this algorithm: contour coding of the regions selected for transmission, followed by coding of the data within the regions. In this paper, an effective single stage conditional arithmetic coder is demonstrated to successfully accomplish this task.
{"title":"An entropy coder for segmentation based video compression","authors":"P. Czerepinski, D. Bull","doi":"10.1109/WIVC.1996.624641","DOIUrl":"https://doi.org/10.1109/WIVC.1996.624641","url":null,"abstract":"Morphological segmentation has recognised advantages for video compression, especially at lower bit rates. A two stage approach has traditionally been employed to encode the interframe data produced by this algorithm: contour coding of the regions selected for transmission, followed by coding of the data within the regions. In this paper, an effective single stage conditional arithmetic coder is demonstrated to successfully accomplish this task.","PeriodicalId":422426,"journal":{"name":"Proceedings of First International Workshop on Wireless Image/Video Communications","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115204329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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