Using negative stuffing retiming for circuit emulation in a packet switching network

A circuit emulation scheme based on negative stuffing retiming that can effectively remove large bursty delay between packets is described. The approach can be applied to various applications such as T-carrier emulation and packet voice and video communication. The key element of the proposed negative stuffing scheme is the stuffing control or when to add negative stuffing. Two stuffing control algorithms are discussed. The first one is very simple and can provide a smooth output without the need of knowing or estimating the transmitter clock. This algorithm transforms large and fast packet arrival jitter into small and slowly varying frequency wander. The second algorithm tries to estimate the transmitter clock to further reduce the wander. Both algorithms will in principle eliminate the large packet arrival jitter completely, and they also ensure no buffer overflow and underflow. To evaluate buffer delay, jitter, and wander of the recovered clock, time domain simulation has been done for DS1 and DS3 signals over a SONET STS-3c-based switching network