Comparison and evaluation of packing schemes for MPEG-2 over ATM using AAL5

Due to the technological advances in video/audio compression and networking, residential broadband services can be supported by carrying MPEG-2 streams over ATM networks as the ATM-to-the-home (ATTH) architecture. Two packing schemes, the 2/2 and 1/2 schemes, have been proposed to constitute AAL5-PDUs (protocol data units) from MPEG-2 transport packets at the ATM adaptation layer (AAL). In this paper, we compare the two packing schemes in several aspects including packing jitter introduced at the AAL and respective implementation costs. We suggest three possible modifications (enhancements) of the 2/2 scheme which eliminate packing delay and have relatively low cost and complexity versus the 1/2 scheme. We also examine the possible queueing jitter occuring at the ATM layer. It is shown that in the worst case the 1/2 scheme produces significant queueing jitter as compared to the packing jitter it saves in the AAL while no queueing jitter is caused by either the basic or modified (enhanced) 2/2 schemes.