Backpressure Algorithm Research Articles

On Combining Shortest-Path and Back-Pressure Routing Over Multihop Wireless Networks

Back-pressure-type algorithms based on the algorithm by Tassiulas and Ephremides have recently received much attention for jointly routing and scheduling over multihop wireless networks. However, this approach has a significant weakness in routing because the traditional back-pressure algorithm explores and exploits all feasible paths between each source and destination. While this extensive exploration is essential in order to maintain stability when the network is heavily loaded, under light or moderate loads, packets may be sent over unnecessarily long routes, and the algorithm could be very inefficient in terms of end-to-end delay and routing convergence times. This paper proposes a new routing/scheduling back-pressure algorithm that not only guarantees network stability (throughput optimality), but also adaptively selects a set of optimal routes based on shortest-path information in order to minimize average path lengths between each source and destination pair. Our results indicate that under the traditional back-pressure algorithm, the end-to-end packet delay first decreases and then increases as a function of the network load (arrival rate). This surprising low-load behavior is explained due to the fact that the traditional back-pressure algorithm exploits all paths (including very long ones) even when the traffic load is light. On the other-hand, the proposed algorithm adaptively selects a set of routes according to the traffic load so that long paths are used only when necessary, thus resulting in much smaller end-to-end packet delays as compared to the traditional back-pressure algorithm .

Large number of queues in tandem: Scaling properties under back-pressure algorithm

We consider a system with N unit-service-rate queues in tandem, with exogenous arrivals of rate ? at queue 1, under a back-pressure (MaxWeight) algorithm: service at queue n is blocked unless its queue length is greater than that of the next queue n+1. The question addressed is how steady-state queues scale as N??. We show that the answer depends on whether ? is below or above the critical value 1/4: in the former case the queues remain uniformly stochastically bounded, while otherwise they grow to infinity. The problem is essentially reduced to the behavior of the system with an infinite number of queues in tandem, which is studied using tools from interacting particle systems theory. In particular, the criticality of load 1/4 is closely related to the fact that this is the maximum possible flux (flow rate) of a stationary totally asymmetric simple exclusion process.

An Adaptive Fuzzy Control Double Leaky Bucket Using Backoff Time and Backpressure in Policing Mechanism Schemes over VDSL Network

When congestion occurs in VDSL networks, it will drop incoming frames because the buffer fills up frames until it over°ows. In backpressure algorithm suitable for low traffic [1], it prevents buffer overflows. In backo® time in leaky bucket over traffic policing mechanism suitable for high traffic [2], Backoff time computations are wildly used in order to avoid the impact on the network performance. In this paper, we propose a fuzzy control double leaky bucket using backpressure and backoff time detects violations in parameter negotiation. We evaluate and compare the performance of a fuzzy control backpressure and backo® time in double-leaky bucket as a policing mechanism (FBBD), a leaky bucket (LB), a jumping window (JW), a triggered jumping window (TJW) and a double-leaky bucket (DLB). The performance of fuzzy control backpressure and backo® time in double-leaky bucket was investigated through fluctuations in telecommunications traffic streams (burst/silent type). Simulation results show that in VDSL frames, the fuzzy logic control system helps improve the performance of our fuzzy control double-leaky bucket using backpressure and backoff time schemes as a policing mechanism much better than conventional policing mechanism by about 25 % in terms of conforming and non-conforming frames once various types of burst/silence traffic are generated.