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297
Dynamic Power Allocation and Routing for Time Varying Wireless Networks
 IEEE Journal on Selected Areas in Communications
, 2003
"... We consider dynamic routing and power allocation for a wireless network with time varying channels. The network consists of power constrained nodes which transmit over wireless links with adaptive transmission rates. Packets randomly enter the system at each node and wait in output queues to be tran ..."
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Cited by 208 (46 self)
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We consider dynamic routing and power allocation for a wireless network with time varying channels. The network consists of power constrained nodes which transmit over wireless links with adaptive transmission rates. Packets randomly enter the system at each node and wait in output queues to be transmitted through the network to their destinations. We establish the capacity region of all rate matrices (# ij ) that the system can stably supportwhere (# ij ) represents the rate of traffic originating at node i and destined for node j. A joint routing and power allocation policy is developed which stabilizes the system and provides bounded average delay guarantees whenever the input rates are within this capacity region. Such performance holds for general arrival and channel state processes, even if these processes are unknown to the network controller. We then apply this control algorithm to an adhoc wireless network where channel variations are due to user mobility, and compare its performance with the GrossglauserTse relay model developed in [13].
Matching output queueing with a combined input output queued switch
 IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS
, 1999
"... The Internet is facing two problems simultaneously: there is a need for a faster switching/routing infrastructure, and a need to introduce guaranteed qualities of service (QoS). Each problem can be solved independently: switches and routers can be made faster by using inputqueued crossbars, instead ..."
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Cited by 149 (17 self)
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The Internet is facing two problems simultaneously: there is a need for a faster switching/routing infrastructure, and a need to introduce guaranteed qualities of service (QoS). Each problem can be solved independently: switches and routers can be made faster by using inputqueued crossbars, instead of shared memory systems; and QoS can be provided using WFQbased packet scheduling. However, until now, the two solutions have been mutually exclusive  all of the work on WFQbased scheduling algorithms has required that switches/routers use outputqueueing, or centralized shared memory. This paper demonstrates that a Combined Input Output Queueing (CIOQ) switch running twice as fast as an inputqueued switch can provide precise emulation of a broad class of packet scheduling algorithms, including WFQ and strict priorities. More precisely, we show that for an switch, a "speedup" of is necessary and a speedup of two is sufficient for this exact emulation. Perhaps most interestingly, this result holds for all traffic arrival patterns. On its own, the result is primarily a theoretical observation; it shows that it is possible to emulate purely OQ switches with CIOQ switches running at approximately twice the linerate. To make the result more practical, we introduce several scheduling algorithms that, with a speedup of two, can emulate an OQ switch. We focus our attention on the simplest of these algorithms, Critical Cells First (CCF), and consider its runningtime and implementation complexity. We conclude that additional techniques are required to make the scheduling algorithms implementable at high speed, and propose two specific strategies.
Fairness and optimal stochastic control for heterogeneous networks
 Proc. IEEE INFOCOM, March 2005. TRANSACTIONS ON NETWORKING, VOL
, 2008
"... Abstract — We consider optimal control for general networks with both wireless and wireline components and time varying channels. A dynamic strategy is developed to support all traffic whenever possible, and to make optimally fair decisions about which data to serve when inputs exceed network capaci ..."
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Cited by 149 (25 self)
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Abstract — We consider optimal control for general networks with both wireless and wireline components and time varying channels. A dynamic strategy is developed to support all traffic whenever possible, and to make optimally fair decisions about which data to serve when inputs exceed network capacity. The strategy is decoupled into separate algorithms for flow control, routing, and resource allocation, and allows each user to make decisions independent of the actions of others. The combined strategy is shown to yield data rates that are arbitrarily close to the optimal operating point achieved when all network controllers are coordinated and have perfect knowledge of future events. The cost of approaching this fair operating point is an endtoend delay increase for data that is served by the network.
HighSpeed Policybased Packet Forwarding Using Efficient Multidimensional Range Matching
 In ACM SIGCOMM
, 1998
"... The ability to provide differentiated services to users with widely varying requirements is becoming increasingly important, and Internet Service Providers would like to provide these differentiated services using the same shared network infrastructure. The key mechanism, that enables differentiatio ..."
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Cited by 136 (0 self)
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The ability to provide differentiated services to users with widely varying requirements is becoming increasingly important, and Internet Service Providers would like to provide these differentiated services using the same shared network infrastructure. The key mechanism, that enables differentiation in a connectionless network, is the packet classification function that parses the headers of the packets, and after determining their context, classifies them based on administrative policies or realtime reservation decisions. Packet classification, however, is a complex operation that can become the bottleneck in routers that try to support gigabit link capacities. Hence, many proposals for differentiated services only require classification at lower speed edge routers and also avoid classification based on multiple fields in the packet header even if it might be advantageous to service providers. In this paper, we present new packet classification schemes that, with a worstcase and tr...
MaxWeight scheduling in a generalized switch: state space collapse and workload minimization in heavy traffic
 Annals of Applied Probability
, 2004
"... We consider a generalized switch model, which includes as special cases the model of multiuser data scheduling over a wireless medium, the inputqueued crossbar switch model and a discrete time version of a parallel server queueing system. Input flows n = 1,...,N are served in discrete time by a swi ..."
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Cited by 113 (9 self)
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We consider a generalized switch model, which includes as special cases the model of multiuser data scheduling over a wireless medium, the inputqueued crossbar switch model and a discrete time version of a parallel server queueing system. Input flows n = 1,...,N are served in discrete time by a switch. The switch state follows a finite state, discrete time Markov chain. In each state m, the switch chooses a scheduling decision k from a finite set K(m), which has the associated service rate vector (µ m 1 (k),..., µm N (k)). We consider a heavy traffic regime, and assume a Resource Pooling (RP) condition. Associated with this condition is a notion of workload X = � n ζnQn, whereζ = (ζ1,...,ζN) is some fixed nonzero vector with nonnegative components, and Q1,...,QN are the queue lengths. We study the MaxWeight discipline which always chooses a decision k maximizing n γn[Qn] β µ m n (k),thatis, k ∈ arg max γn[Qn] i n β µ m n (i), where β>0, γ1> 0,...,γN> 0 are arbitrary parameters. We prove that under MaxWeight scheduling and the RP condition, in the heavy traffic limit, the queue length process has the following properties: (a) The vector (γ1Q β 1,...,γNQ β N) is always proportional to ζ (this is “State Space Collapse”), (b) the workload process converges to a Reflected Brownian Motion, (c) MaxWeight minimizes the workload among all disciplines. As a corollary of these properties, MaxWeight asymptotically minimizes the holding cost rate n γnQ β+1
Load Balanced Birkhoffvon Neumann Switches, Part II: Multistage Buffering
, 2001
"... The main objective of this sequel is to solve the outofsequence problem that occurs in the load balanced Birkhoffvon Neumann switch with onestage buffering. We do this by adding a loadbalancing buffer in front of the first stage and a resequencingandoutput buffer after the second stage. Moreo ..."
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Cited by 103 (13 self)
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The main objective of this sequel is to solve the outofsequence problem that occurs in the load balanced Birkhoffvon Neumann switch with onestage buffering. We do this by adding a loadbalancing buffer in front of the first stage and a resequencingandoutput buffer after the second stage. Moreover, packets are distributed at the first stage according to their flows, instead of their arrival times in Part I. In this paper, we consider multicasting ows with two types of scheduling policies: the First Come First Served (FCFS) policy and the Earliest Deadline First (EDF) policy. The FCFS policy requires a jitter control mechanism in front of the second stage to ensure proper ordering of the traffic entering the second stage. For the EDF scheme, there is no need for jitter control. It uses the departure times of the corresponding FCFS outputbuffered switch as deadlines and schedules packets according to their deadlines. For both policies, we show that the endtoend delay through our multistage switch is bounded above by the sum of the delay from the corresponding FCFS outputbuffered switch and a constant that only depends on the size of the switch and the number of multicasting flows supported by the switch.
The Tiny Tera: A Packet Switch Core
, 1996
"... In this paper, we present the Tiny Tera: a small packet switch with an aggregate bandwidth of 320Gb/s. The Tiny Tera is a CMOSbased inputqueued, fixedsize packet switch suitable for a wide range of applications such as a highperformance ATM switch, the core of an Internet router or as a fast mult ..."
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Cited by 87 (5 self)
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In this paper, we present the Tiny Tera: a small packet switch with an aggregate bandwidth of 320Gb/s. The Tiny Tera is a CMOSbased inputqueued, fixedsize packet switch suitable for a wide range of applications such as a highperformance ATM switch, the core of an Internet router or as a fast multiprocessor interconnect. Using offtheshelf technology, we plan to demonstrate that a very highbandwidth switch can be built without the need for esoteric optical switching technology. By employing novel scheduling algorithms for both unicast and multicast traffic, the switch will have a maximum throughput close to 100%. Using novel highspeed chiptochip serial link technology, we plan to reduce the physical size and complexity of the switch, as well as the system pincount.
Energy optimal control for time varying wireless networks
 IEEE Trans. Inform. Theory
, 2006
"... Abstract — We develop a dynamic control strategy for minimizing energy expenditure in a time varying wireless network with adaptive transmission rates. The algorithm operates without knowledge of traffic rates or channel statistics, and yields average power that is arbitrarily close to the minimum p ..."
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Cited by 87 (28 self)
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Abstract — We develop a dynamic control strategy for minimizing energy expenditure in a time varying wireless network with adaptive transmission rates. The algorithm operates without knowledge of traffic rates or channel statistics, and yields average power that is arbitrarily close to the minimum possible value achieved by an algorithm optimized with complete knowledge of future events. Proximity to this optimal solution is shown to be inversely proportional to network delay. We then present a similar algorithm that solves the related problem of maximizing network throughput subject to peak and average power constraints. The techniques used in this paper are novel and establish a foundation for stochastic network optimization.
On the speedup required for workconserving crossbar switches
, 1999
"... This paper describes the architecture for a workconserving server using a combined I/Obuffered crossbar switch. The switch employs a novel algorithm based on output occupancy, the lowest occupancy output first algorithm (LOOFA), and a speedup of only two. A workconserving switch provides the same ..."
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Cited by 80 (1 self)
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This paper describes the architecture for a workconserving server using a combined I/Obuffered crossbar switch. The switch employs a novel algorithm based on output occupancy, the lowest occupancy output first algorithm (LOOFA), and a speedup of only two. A workconserving switch provides the same throughput performance as an outputbuffered switch. The workconserving property of the switch is independent of the switch size and input traffic pattern. We also present a suite of algorithms that can be used in combination with LOOFA. These algorithms determine the fairness and delay properties of the switch. We also describe a mechanism to provide delay bounds for realtime traffic using LOOFA. These delay bounds are achievable without requiring outputbuffered switch emulation.