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198
Joint congestion control, routing and MAC for stability and fairness in wireless networks
 IEEE Journal on Selected Areas in Communications
, 2006
"... In this work, we describe and analyze a joint scheduling, routing and congestion control mechanism for wireless networks, that asymptotically guarantees stability of the buffers and fair allocation of the network resources. The queue lengths serve as common information to different layers of the ne ..."
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Cited by 66 (8 self)
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In this work, we describe and analyze a joint scheduling, routing and congestion control mechanism for wireless networks, that asymptotically guarantees stability of the buffers and fair allocation of the network resources. The queue lengths serve as common information to different layers of the network protocol stack. Our main contribution is to prove the asymptotic optimality of a primaldual congestion controller, which is known to model different versions of TCP well.
Exploiting Decentralized Channel State Information for Random Access
, 2002
"... We study the use of channel state information for random access in fading channels. Traditionally, random access protocols have been designed by assuming simple models for the physical layer where all users are symmetric and there is no notion of channel state. We introduce a reception model that ta ..."
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Cited by 64 (18 self)
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We study the use of channel state information for random access in fading channels. Traditionally, random access protocols have been designed by assuming simple models for the physical layer where all users are symmetric and there is no notion of channel state. We introduce a reception model that takes into account the channel states of various users. Under the assumption that each user has access to his channel state information (CSI), we propose a variant of Slotted ALOHA protocol for medium access control, where the transmission probability is allowed to be a function of the CSL The function is called the transmission control scheme. Assuming the finite user infinite buffer model we derive expressions for the maximum stable throughput of the system. We introduce the notion of asymptotic stable throughput (AST) that is the maximum stable throughput as the number of users goes to infinity. We consider two types of transmission control namely population independent transmission control (PITC) where the transmission control is not a function of the size of the network and population dependent transmission control where the transmission control is a function of the size of the network. We obtain expressions for the AST achievable with PITC. For population dependent transmission control, we introduce a particular transmission control that can potentially lead to significant gains in AST. For both PITC and PDTC, we show that the effect of transmission control is equivalent to changing the probability distribution of the channel state. The theory is then applied to CDMA networks with Linear Minimum Mean Square Error (LMMSE) receivers and Matched Filters (MF) to illustrate the effectiveness of utilizing channel state. It is shown that through the use of channel state, with an...
Using Channel State Dependent Packet Scheduling to improve TCP throughput over wireless LANs
, 1996
"... this paper we study the effect of burst packet errors and error recovery mechanisms employed in wireless MAC protocols on the performance of transport protocols such as TCP. Most wireless LAN link layer protocols recover from packet losses by retransmitting lost segments. When the wireless channel i ..."
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Cited by 59 (2 self)
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this paper we study the effect of burst packet errors and error recovery mechanisms employed in wireless MAC protocols on the performance of transport protocols such as TCP. Most wireless LAN link layer protocols recover from packet losses by retransmitting lost segments. When the wireless channel is in a burst error state, most retransmission attempts fail, thereby causing poor utilization of the wireless channel. Furthermore, in the event of multiple sessions sharing a wireless link, FIFO packet scheduling can cause the HOL blocking effect, resulting in unfair sharing of the bandwidth. This observation leads to a new class of packet dispatching methods which explicitly take wireless channel characteristics into consideration in making packet dispatching decisions. We compare a variety of channel state dependent packet (CSDP) scheduling methods with a view towards enhancing the performance of transport layer sessions. Our results indicate that by employing a CSDP scheduler at the wireless LAN device driver level, significant improvement in channel utilization can be achieved in typical wireless LAN configurations.
Power and server allocation in a multibeam satellite with time varying channels
 in Proceedings of IEEE INFOCOM ’02
, 2002
"... Abstract We consider power and server allocation in a multibeam satellite downlink which transmits data to N different ground locations over N timevarying channels. Packets destined for each ground location are stored in separate queues, and the server rate for each queue i depends on the power p ..."
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Cited by 49 (11 self)
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Abstract We consider power and server allocation in a multibeam satellite downlink which transmits data to N different ground locations over N timevarying channels. Packets destined for each ground location are stored in separate queues, and the server rate for each queue i depends on the power p i (t) allocated to that server and the channel state c i (t) according to a concave ratepower curve µ i (p i, c i). We establish the capacity region of all arrival rate vectors (λ 1,...,λ N) which admit a stabilizable system. For the case when channel states and arrivals are iid from timeslot to timeslot, we develop a particular power allocation policy which stabilizes the system whenever the rate vector lies within the capacity region. Such stability is guaranteed even if the channel model and the specific arrival rates are unknown. As a special case, this analysis verifies stability of the “ChoosetheKLargestConnectedQueues ” policy when channels can be in one of two states (ON or OFF) and K servers are allocated at every timestep (K<N). These results are extended to treat a joint problem of routing and power allocation, and a throughput maximizing algorithm for this joint problem is constructed. Finally, we address the issue of interchannel interference, and develop a modified policy when power vectors are constrained to feasible activation sets. Our analysis and problem formulation is also applicable to power control for wireless systems. I.
Optimal energy and delay tradeoffs for multiuser wireless downlinks
 Proc. IEEE INFOCOM
, 2006
"... Abstract — We consider the fundamental delay tradeoffs for minimizing energy expenditure in a multiuser wireless downlink with randomly varying channels. First, we extend the BerryGallager bound to a multiuser context, demonstrating that any algorithm that yields average power within O(1/V) of th ..."
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Cited by 38 (14 self)
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Abstract — We consider the fundamental delay tradeoffs for minimizing energy expenditure in a multiuser wireless downlink with randomly varying channels. First, we extend the BerryGallager bound to a multiuser context, demonstrating that any algorithm that yields average power within O(1/V) of the minimum power required for network stability must also have an average queueing delay greater than or equal to Ω ( √ V). We then develop a class of algorithms, parameterized by V, that come within a logarithmic factor of achieving this fundamental tradeoff. The algorithms overcome an exponential state space explosion, and can be implemented in real time without apriori knowledge of traffic rates or channel statistics. Further, we discover a “superfast ” scheduling mode that beats the BerryGallager bound in the exceptional case when power functions are piecewise linear. Index Terms — queueing analysis, stability, optimization, stochastic control, asymptotic tradeoffs
On Delay Performance Gains from Network Coding
 Proc. of Conference on Information Sciences and Systems (CISS
, 2006
"... Abstract — This paper analyzes the gains in delay performance resulting from network coding. We consider a model of file transmission to multiple receivers from a single base station. Using this model, we show that gains in delay performance from network coding with or without channel side informati ..."
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Cited by 34 (9 self)
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Abstract — This paper analyzes the gains in delay performance resulting from network coding. We consider a model of file transmission to multiple receivers from a single base station. Using this model, we show that gains in delay performance from network coding with or without channel side information can be substantial compared to conventional scheduling methods for downlink transmission. I.
Optimal Backpressure Routing for Wireless Networks with MultiReceiver Diversity
, 2006
"... We consider the problem of optimal scheduling and routing in an adhoc wireless network with multiple traffic streams and time varying channel reliability. Each packet transmission can be overheard by a subset of receiver nodes, with a transmission success probability that may vary from receiver t ..."
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Cited by 34 (6 self)
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We consider the problem of optimal scheduling and routing in an adhoc wireless network with multiple traffic streams and time varying channel reliability. Each packet transmission can be overheard by a subset of receiver nodes, with a transmission success probability that may vary from receiver to receiver and may also vary with time. We develop a simple backpressure routing algorithm that maximizes network throughput and expends an average power that can be pushed arbitrarily close to the minimum average power required for network stability, with a corresponding tradeoff in network delay. The algorithm can be implemented in a distributed manner using only local link error probability information, and supports a “blind transmission” mode (where error probabilities are not required) in special cases when the power metric is neglected and when there is only a single destination for all traffic streams.
A large deviations analysis of scheduling in wireless networks
 Earlier versions of the paper appeared in the IEEE CDC 2004, IEEE CDC 2005 and IEEE ISIT
, 2006
"... We consider a cellular network consisting of a base station and N receivers. The channel states of the receivers are assumed to be identical and independent of each other. The goal is to compare the throughput of two different scheduling policies (a queuelengthbased policy and a greedy scheduling ..."
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Cited by 33 (5 self)
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We consider a cellular network consisting of a base station and N receivers. The channel states of the receivers are assumed to be identical and independent of each other. The goal is to compare the throughput of two different scheduling policies (a queuelengthbased policy and a greedy scheduling policy) given an upper bound on the queue overflow probability or the delay violation probability. We first consider a simple channel model, where each channel is assumed to be in one of two states (ON or OFF). Given an upper bound on the delay violation probability or an upper bound on the queue overflow probability, we show that the total network throughput of the queuelengthbased policy is strictly larger than the throughput of the greedy policy for all N. Further, the throughput of the queuelengthbased policy is a strictly increasing function of N while the throughput of the greedy policy does not have this property. Finally, for general channel state models, we show that the relative performances of the the greedy and QLB policies have a similar behavior. policy.
Downlink scheduling and resource allocation for OFDM systems
 IN CISS
, 2006
"... Abstract—We consider scheduling and resource allocation for the downlink of a cellular OFDM system, with various practical considerations including integer carrier allocations, different subchannelization schemes, a maximum SNR constraint per tone, and “selfnoise ” due to channel estimation errors ..."
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Cited by 32 (14 self)
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Abstract—We consider scheduling and resource allocation for the downlink of a cellular OFDM system, with various practical considerations including integer carrier allocations, different subchannelization schemes, a maximum SNR constraint per tone, and “selfnoise ” due to channel estimation errors and phase noise. During each timeslot a subset of users must be scheduled for transmission, and the available tones and transmission power must be allocated among the selected users. Employing a gradientbased scheduling scheme presented in earlier papers reduces this to an optimization problem to be solved in each timeslot. Using dual decomposition techniques, we give an optimal algorithm for this problem when multiple users can timeshare each carrier. We then give several low complexity heuristics that enforce an integer constraint on the carrier allocation. Simulations show that the algorithms presented all achieve similar performance under a wide range of scenarios, and that the performance gap between the optimal and suboptimal algorithms widens when per user SNR constraints or channel estimation errors are considered. I.
Order optimal delay for opportunistic scheduling in multiuser wireless uplinks and downlinks
 Proc. of Allerton Conf. on Communication, Control, and Computing (invited paper
, 2006
"... Abstract — We consider a onehop wireless network with independent time varying channels and N users, such as a multiuser uplink or downlink. We first show that general classes of scheduling algorithms that do not consider queue backlog necessarily incur average delay that grows at least linearly wi ..."
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Cited by 28 (6 self)
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Abstract — We consider a onehop wireless network with independent time varying channels and N users, such as a multiuser uplink or downlink. We first show that general classes of scheduling algorithms that do not consider queue backlog necessarily incur average delay that grows at least linearly with N. We then construct a dynamic queuelength aware algorithm that stabilizes the system and achieves an average delay that is independent of N. This is the first analytical demonstration that O(1) delay is achievable in such a multiuser wireless setting. The delay bounds are achieved via a technique of queue grouping together with basic Lyapunov stability and statistical multiplexing concepts.