ATM中的图象信元丢失保护技术

Protection Technology for Image Cell Loss in ATM

提出了基于正交镜象滤波器和离散余弦变换的分层编码技术，该技术可以有效地防止异步转移模式（ＡＴＭ）网中因信元丢失引起的图象质量恶化，从而实现以ＡＴＭ方式传送高质量稳定的动图象．还阐述了用该技术实现不同分辩率终端通信的方法．文中给出了该编码的原理和计算机模拟结果．

This paper describes a kind of subband encoding technology on the basis of a 2-dimensional quadrature mirror filter (QMF) and discrete cosine transform (DCT). This technology can be used to compensate for the image cell loss in Asynchronous Transfer Mode (ATM) networks, and provide high qualify.image communication in ATM. The impact of different length filters on the reconstructed image quality is also discussed and it is concluded that the best filter is 12-B considering both operation time and SNR. To prevent deterioration of recovery image quality due to cell loss, several different losing modes are investigated, with the conclusion that the low frequency subband iS of greatest importance and should be given the prior protection. The scales of subbands also affect the reconstructed image quality moderately. More splitting subbands lead to more operation time and lower SNR and lower bit rated. Finally, the communication is realised between two terminals with different resolution scales using the above-mentioned technology.