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65
Novel architectures and algorithms for delay reduction in backpressure scheduling and routing
 Proceedings of IEEE INFOCOM 2009 MiniConference
, 2009
"... The backpressure algorithm is a wellknown throughputoptimal algorithm. However, its delay performance may be quite poor even when the traffic load is not close to network capacity due to the following two reasons. First, each node has to maintain a separate queue for each commodity in the network ..."
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Cited by 58 (3 self)
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The backpressure algorithm is a wellknown throughputoptimal algorithm. However, its delay performance may be quite poor even when the traffic load is not close to network capacity due to the following two reasons. First, each node has to maintain a separate queue for each commodity in the network, and only one queue is served at a time. Second, the backpressure routing algorithm may route some packets along very long routes. In this paper, we present solutions to address both of the above issues, and hence, improve the delay performance of the backpressure algorithm. One of the suggested solutions also decreases the complexity of the queueing data structures to be maintained at each node. I.
Routing Without Routes: The Backpressure Collection Protocol
"... Current data collection protocols for wireless sensor networks are mostly based on quasistatic minimumcost routing trees. We consider an alternative, highlyagile approach called backpressure routing, in which routing and forwarding decisions are made on a perpacket basis. Although there is a con ..."
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Cited by 58 (6 self)
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Current data collection protocols for wireless sensor networks are mostly based on quasistatic minimumcost routing trees. We consider an alternative, highlyagile approach called backpressure routing, in which routing and forwarding decisions are made on a perpacket basis. Although there is a considerable theoretical literature on backpressure routing, it has not been implemented on practical systems to date due to concerns about packet looping, the effect of link losses, large packet delays, and scalability. Addressing these concerns, we present the Backpressure Collection Protocol (BCP) for sensor networks, the first ever implementation of dynamic backpressure routing in wireless networks. In particular, we demonstrate for the first time that replacing the traditional FIFO queue service in backpressure routing with LIFO queues reduces the average endtoend packet delays for delivered packets drastically (75 % under high load, 98 % under low load). Further, we improve backpressure scalability by introducing a new concept of floating queues into the backpressure framework. Under static network settings, BCP shows a more than 60 % improvement in maxmin rate over the state of the art Collection Tree Protocol (CTP). We also empirically demonstrate the superior delivery performance of BCP in highly dynamic network settings, including conditions of extreme external interference and highly mobile sinks. 1.
Delaybased network utility maximization
 in Proc. IEEE INFOCOM 2010
, 2010
"... Abstract—It is well known that maxweight policies based on a queue backlog index can be used to stabilize stochastic networks, and that similar stability results hold if a delay index is used. Using Lyapunov Optimization, we extend this analysis to design a utility maximizing algorithm that uses ex ..."
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Cited by 22 (1 self)
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Abstract—It is well known that maxweight policies based on a queue backlog index can be used to stabilize stochastic networks, and that similar stability results hold if a delay index is used. Using Lyapunov Optimization, we extend this analysis to design a utility maximizing algorithm that uses explicit delay information from the headofline packet at each user. The resulting policy is shown to ensure deterministic worstcase delay guarantees, and to yield a throughpututility that differs from the optimally fair value by an amount that is inversely proportional to the delay guarantee. Our results hold for a general class of 1hop networks, including packet switches and multiuser wireless systems with time varying reliability. I.
Optimal Control of Wireless Networks with Finite Buffers
"... This paper considers network control for wireless networks with finite buffers. We investigate the performance of joint flow control, routing, and scheduling algorithms which achieve high network utility and deterministically bounded backlogs inside the network. Our algorithms guarantee that buffers ..."
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Cited by 21 (2 self)
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This paper considers network control for wireless networks with finite buffers. We investigate the performance of joint flow control, routing, and scheduling algorithms which achieve high network utility and deterministically bounded backlogs inside the network. Our algorithms guarantee that buffers inside the network never overflow. We study the tradeoff between buffer size and network utility and show that if internal buffers have size (N − 1)/ɛ then a high fraction of the maximum utility can be achieved, where ɛ captures the loss in utility and N is the number of network nodes. The underlying scheduling/routing component of the considered control algorithms requires ingress queue length information (IQI) at all network nodes. However, we show that these algorithms can achieve the same utility performance with delayed ingress queue length information. Numerical results reveal that the considered algorithms achieve nearly optimal network utility with a significant reduction in queue backlog compared to the existing algorithm in the literature. Finally, we discuss extension of the algorithms to wireless networks with timevarying links.
On Scheduling for Minimizing EndtoEnd Buffer Usage over Multihop Wireless Networks
"... Abstract—While there has been much progress in designing backpressure based stabilizing algorithms for multihop wireless networks, endtoend performance (e.g., endtoend buffer usage) results have not been as forthcoming. In this paper, we study the endtoend buffer usage (sum of buffer utilizati ..."
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Cited by 12 (0 self)
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Abstract—While there has been much progress in designing backpressure based stabilizing algorithms for multihop wireless networks, endtoend performance (e.g., endtoend buffer usage) results have not been as forthcoming. In this paper, we study the endtoend buffer usage (sum of buffer utilization along a flow path) over a network with general topology and with fixed, loopfree routes using a largedeviations approach. We first derive bounds on the best performance that any scheduling algorithm can achieve. Based on the intuition from the bounds, we propose a class of (backpressurelike) scheduling algorithms called αβalgorithms. We show that the parameters α and β can be chosen such that the system under the αβalgorithm performs arbitrarily closely to the best possible scheduler (formally the decay rate function for endtoend buffer overflow is shown to be arbitrarily close to optimal in the largebuffer regime). We also develop variants which have the same asymptotic optimality property, and also provide good performance in the smallbuffer regime. Our results are substantiated using both analysis and simulation. I.
Scheduling for endtoend deadlineconstrained traffic with reliability requirements in multihop networks technical report.” [Online]. Available: http://somewhere APPENDIX A PROOF OF PROPOSITION 4 To prove Proposition 4, we consider our onehop system as
 Lemma 1: limm!1 cm = c for all A ∈ (p). Proof: For all A ∈ (p), we have ∑f (1 − pf )af < T . We
"... Abstract—We attack the challenging problem of designing a scheduling policy for endtoend deadlineconstrained traffic with reliability requirements in a multihop network. It is wellknown that the endtoend delay performance for a multihop flow has a complex dependence on the highorder statist ..."
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Cited by 10 (1 self)
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Abstract—We attack the challenging problem of designing a scheduling policy for endtoend deadlineconstrained traffic with reliability requirements in a multihop network. It is wellknown that the endtoend delay performance for a multihop flow has a complex dependence on the highorder statistics of the arrival process and the algorithm itself. Thus, neither the earlier optimization based approaches that aim to meet the longterm throughput demands, nor the solutions that focus on a similar problem for singlehop flows directly apply. Moreover, a dynamic programmingbased approach becomes intractable for such multitime scale QualityofService(QoS)constrained traffic in a multihop environment. This motivates us in this work to develop an alternative model that enables us to exploit the degree of freedom in choosing appropriate service discipline. Based on the new model, we propose two alternative solutions, first based on a Lyapunovdrift minimization approach, and second based on a novel relaxed optimizationformulation. We provide extensive numerical results to compare the performance of both of these solutions to throughputoptimal backpressuretype schedulers and to longest waiting time based schedulers that have provably optimal asymptotic performance characteristics. Our results reveal that the dynamic choice of service discipline of our proposed solutions yields substantial performance improvements compared to both of these types of traditional solutions under nonasymptotic conditions. I.
Backpressure routing for intermittently connected networks
"... Abstract—We study a mobile wireless network where groups or clusters of nodes are intermittently connected via mobile “carriers” (the carriers provide connectivity over time among different clusters of nodes). Over such networks (an instantiation of a delay tolerant network), it is wellknown that t ..."
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Cited by 8 (0 self)
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Abstract—We study a mobile wireless network where groups or clusters of nodes are intermittently connected via mobile “carriers” (the carriers provide connectivity over time among different clusters of nodes). Over such networks (an instantiation of a delay tolerant network), it is wellknown that traditional routing algorithms perform very poorly. In this paper, we propose a twolevel BackPressure with SourceRouting algorithm (BP+SR) for such networks. The proposed BP+SR algorithm separates routing and scheduling within clusters (fast timescale) from the communications that occur across clusters (slow timescale), without loss in network throughput (i.e., BP+SR is throughputoptimal). More importantly, for a source and destination node that lie in different clusters, the traditional backpressure algorithm results in large queue lengths at each node along its path. This is because the queue dynamics are driven by the slowest timescale (i.e., that of the carrier nodes) along the path between the source and destination, which results in very large endtoend delays. On the otherhand, we show that the twolevel BP+SR algorithm maintains large queues only at a very few nodes, and thus results in orderwise smaller endtoend delays. We provide analytical as well as simulation results to confirm our claims. I.
Backpressurebased PacketbyPacket Adaptive Routing in Communication Networks
"... Backpressurebased adaptive routing algorithms where each packet is routed along a possibly different path have been extensively studied in the literature. However, such algorithms typically result in poor delay performance and involve high implementation complexity. In this paper, we develop a new ..."
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Cited by 6 (0 self)
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Backpressurebased adaptive routing algorithms where each packet is routed along a possibly different path have been extensively studied in the literature. However, such algorithms typically result in poor delay performance and involve high implementation complexity. In this paper, we develop a new adaptive routing algorithm built upon the widelystudied backpressure algorithm. We decouple the routing and scheduling components of the algorithm by designing a probabilistic routing table which is used to route packets to perdestination queues. The scheduling decisions in the case of wireless networks are made using counters called shadow queues. The results are also extended to the case of networks which employ simple forms of network coding. In that case, our algorithm provides a lowcomplexity solution to optimally exploit the routingcoding tradeoff.
Throughputoptimal scheduling in multihop wireless networks without perflow information
 Networking, IEEE/ACM Transactions on
, 2013
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