An efficient ATM voice service with flexible jitter and delay guarantees

Abstract

Abstract-A transmission and multiplexing strategy appropriate for voice over asynchronous transfer mode (ATM), called delayed frame queueing (DFQ), is proposed. This frame-based strategy has features in common with the synchronous transfer mode and is thus well suited to service synchronous applications such as voice, while retaining the statistical multiplexing capabilities of ATM. In particular, the DFQ service discipline can provide explicit and nontrivial bounds for queue delay and jitter, for both bursty as well as continuous traffic streams. Furthermore, the DFQ discipline can combine a wide range of delay and jitter bounds while also managing the distribution of quality of service violations among the traffic streams when congestion occurs. Jitter control is performed at the network periphery and thus does not negatively influence multiplexing gain at intermediate nodes. This efficient strategy has major implications in terms of the preferred alternatives chosen by clients when implementing source clock recovery for voice. DFQ allows the entire range of implementation alternatives for voice over ATM to be appropriately serviced, such as ATM adaptation layer types 1 and 2 (AAL1/2), adaptive playout, and immediate playout.

Design and simulation of an efficient real-time traffic scheduler with jitter and delay guarantees

“…Now, it is easy to derive from (1), (3), and (7) that can also be calculated using (8) In other words, the notion of jitter described in Section II-A is actually consistent with the definition in As we know, the eligible time of a cell is the time when that cell can be transmitted immediately without jitter bound violation. In the following, we show that is bounded by (9) if we set the eligible time, , as…”

“…However, the implementation complexity will be an important metric to evaluate the worth of the schedulers. Hence, we investigate the implementation complexity for MGFQ and make a comparison with other scheduling algorithms, such as JEDD [4], DFQ [8], RPQ [9], RPQ [17], etc., in this section.…”

“…In addition, extra pointer-operations are needed to concatenate the cells in FIFO into FIFO [17]. An alternative approach, called DFQ [8], also adopts the concept of RPQ to achieve low-complexity traffic scheduler with delay/jitter guarantees. However, as mentioned in Section I, the number of the FIFO-queues set is increased linearly proportional to the supported jitter levels.…”

“…Two classes of guaranteed jitter bound are simulated for : a tight bound of 1 ms and a loose bound of 13 ms. We assume only a loose jitter bound of 6.5 ms is guaranteed for the cross traffic. Note that our MGFQ algorithm requires only one set of FIFO queues in node 3 to provide two classes of jitter bounds, while two sets of FIFO queues are needed in DFQ [8]. Fig.…”

“…However, the implementation cost for such buffer management to be applied in combination with the JEDD algorithm could be very high because of the winner selection operations of the JEDD in the output buffer. In order to reduce implementation complexity, Pocher et alintroduces the delayed frame queueing (DFQ) service discipline [8] and adopts the concept of rotating-priority-queue (RPQ) [9] proposed by Liebeherr et al to achieve the delay and jitter guarantees. The service queue of each link is organized as a sequential row of several FIFO buffers.…”