This letter mathematically proves that the performance of the new protocol in Ref. [1] is better than that of the existing protocol. It was proposed that a frame from an access device is delivered over the access link and then it is multiplexed and packed into ATM cell at an access node and then the cell is carried toward a voice gateway, by using a method to split two sublayers in AAL2. That means one sublayer is implemented at the subscriber access device and the other sublayer is implemented at the access node. Access devices using the protocol achieve higher utilization of CID and waste fewer ATM resource per the access device. Mathematical analysis is performed on the proposed and existing protocol, and both upstream cell rate and padding probability are calculated. The proposed protocol shows lower upstream traffic rate and padding cell probability than the existing protocol.

This letter proposes that by separating the two sublayers within AAL2 for VoDSL, a non-ATM-based IAD at customer premises can support AAL2 service through a DSLAM including new functions at the central office. To achieve this goal, AAL2 SSCS for bearer channels is located at the CPE. Also, AAL2 CPS and AAL2 SSCS for frame mode service including SSSAR and SSTED are located at the DSLAM. By doing so, one endpoint of an ATM connection at the customer side moves to the DSLAM. All bearer channels, CAS or CCS signaling and DSS1 relay messages from the customer side are transmitted to voice gateway transparently. As a result, the ATM connection using AAL2 can multiplex CPS packets from more AAL2 users, which improves multiplexing gain, minimizes waiting probability, and significantly decreases the number of cells into ATM networks. The simulation shows that the proposed method results in less ATM traffic and padded cell ratio, compared with the existing method.