Manivasakan Rathinam

This paper discusses the condition under which the jitter buffer at the receiver is to be operated for minimum output variance in a TDMoIP framework. The above study would be useful in the design of synchronization algorithms at the receiver of a TDMoIP network. This work uses the results derived in [1] to the above problem. We model the receiver jitter buffer as a M/G/1 queueing system with EARMA correlations between the inter-arrival times and the service times. The motivation for the above correlation structure is that, if the service intervals depend on the arrival rate and there is correlation within service times, we can achieve a constant bit rate at the receiver, that is, emulate the TDM stream as it was sent at the transmitter. Also, analysis of such a correlated queue is analytically tractable. We derived the variance of the inter departure times, of the above queue. The analysis of the departure process and the waiting times of incoming packets of this correlated queue and the relevant simulations show that if the variance of the inter departure time process constituting output TDM stream is to be less than that of the inter arrival time process of the jitter buffer, which is modeled as M/G/1 queue, then the mean waiting time of the packets in the jitter buffer would necessarily be greater than that of independent (M/M/1) case. © 2012 IEEE.

Time Division Multiplexing (TDM) over Packet Switched Network (PSN) is a pseudo wire technology for emulating TDM Circuits over Packet Networks. Conceptually, the important ingredients of the above technology are to implement the following, in the PSN (i) Quality of Service (QoS) which is implemented through scheduling at the intermediate nodes that gives priority to packets containing 'TDM' payload (ii) timing and synchronization and (iii) scheduling in the jitter buffer for minimum output variance. Among these, this paper addresses (iii) as a first step assuming that the PSN provisions the "unacknowledged virtual circuit" (the main components of 'virtual circuit' are QoS and connection-oriented service). This work targets to implement a scheduling algorithm (service intervals) in jitter buffer at the receiver, such that the variance of inter-departure intervals of TDM stream is minimized. This is accomplished by the buffer modelled as M/G/l queueing system with Auto-Regressive AR (1) correlations within service intervals. The motivation for the above correlation structure is two-fold. First, given the correlations within the service intervals, such a correlation results in reduction of variance in the inter-departure interval. The other is that the analysis of such a correlated queue is analytically tractable. The variance of the inter-departure time is presented. The analysis of the departure process, the waiting times of incoming packets of this correlated queue aids in determining the correlation parameter that are sub-optimal in the context of TDMoPSN. Our study also includes a M/G/l queue with AR (1) cross-correlations between the inter-arrival and the service times. A G/G/l queue in which the inter arrivals are correlated, and with AR (1) correlations of the above two types are also studied. Extensive simulations demonstrate our analytical and approximation results.

Time Division Multiplexing over Internet Protocol (TDMoIP) is a pseudowire technology for emulating TDM circuits over Internet Protocol (IP) networks. In such networks, timing and synchronization plays a key role in achieving the required jitter in terms of variance of interdeparture interval. A jitter buffer is used at the receiver, to circumvent the impairment of the packet networks: delay, jitter and loss. But, out of these, delay and loss can't be compensated for, while QoS in IP networks is used to minimize them. The jitter (or variance of packet delay) can be reduced to a tolerable level at the receiving Inter Working Function. A tradeoff between delay and jitter is required to achieve the desired jitter. This paper presents the condition under which the jitter buffer at the receiver is to be operated for minimum output variance in a TDMoIP framework, to achieve minimum slip rate and thus better voice quality. The receiver jitter buffer is modeled as a correlated M/G/1 queueing system with EARMA correlations between the interarrival and the service times. The motivation for the above correlation structure is that, given the correlations within the service intervals, the EARMA correlation results in reduction of variance in the interdeparture interval. This is a step towards achieving CBR upstream. The key advantage of using EARMA correlation is that the analysis of such a correlated queue is analytically tractable. The variance of the interdeparture times of the above queue is presented. The analysis of the departure process, the waiting times of incoming packets of this correlated queue and the relevant simulations show that if the variance of the interdeparture time process constituting output TDM stream is to be less than that of the interarrival time process of the jitter buffer, which is modeled as M/G/1 queue, then the mean waiting time of the packets in the jitter buffer would be greater than that of independent (M/M/1) case. The values of the parameters of the M/G/1 queue which minimizes the variance of interdeparture interval are identified. Our study also included a G/G/1 queue in which interarrivals are also correlated. Extensive simulations demonstrate our analytical results. Copyright © IARIA, 2012.