TY - JOUR
T1 - PHY-Aware distributed scheduling for ad hoc communications with physical interference model
AU - Ge, Weiyan
AU - Zhang, Junshan
AU - Wieselthier, Jeffrey E.
AU - Shen, Xuemin
N1 - Funding Information:
Manuscript received June 17, 2008; revised December 22, 2008; accepted January 1, 2009. The associate editor coordinating the review of this paper and approving it for publication was Y. Fang. W. Ge is with Qualcomm Inc. San Diego, CA, 92121, USA (e-mail: wge@qualcomm.com). J. Zhang is with the Department of Electrical Engineering, Arizona State University, Tempe, AZ, 85287, USA (e-mail: junshan.zhang@asu.edu). J. E. Wieselthier is currently with Wieselthier Research, Silver Spring, MD 20901, USA (e-mail: jeff@wieselthier.com). X. (S.) Shen is with the Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada (e-mail: xshen@bbcr.uwaterloo.ca). This research is supported in part by the National Science Foundation through the grants ANI-0238550 and CNS-0721820. Digital Object Identifier 10.1109/TWC.2008.080798
PY - 2009/5
Y1 - 2009/5
N2 - We consider a random-access-based ad hoc network, where different links use mini-slots to contend for the channel, and then successful links transmit data packets, as in CSMA. The focus of our study is to develop optimal strategies for physicallayer-aware (PHY-aware) distributed scheduling, which involves a joint process of channel probing and distributed scheduling. Because of channel fading and cochannel interference, the signalto-interference-plus-noise-ratio (SINR) across links is highly dynamic and can exhibit significant variation. In the low SINR case, further channel probing is likely to lead to better SINR conditions and hence yield higher throughput. The desired tradeoff boils down to judiciously choosing the optimal stopping strategy for channel probing before data transmissions. In this paper, we investigate PHY-aware distributed scheduling, aiming to maximize the overall network throughput. The problem under consideration is inherently challenging: 1) multiple links can transmit successfully simultaneously and the number of simultaneously transmitting links is random; and 2) the network throughput is the sum rate of all transmitting links, but each link involved in the transmission has no knowledge of the instantaneous rates of other links, and the stopping decision is made in a distributed manner based on local information only. We use optimal stopping theory to tackle this challenge, and show that the optimal policy for distributed scheduling has a threshold structure. Accordingly, after a channel probing, a link would proceed with data transmissions only if a function of its instantaneous rate is greater than the optimal rate threshold. Observing that the network throughput depends heavily on the contention probability of each link, we generalize the study to jointly optimize the rate threshold and the contention probability, and propose a two-stage algorithm for computing the pair of optimal rate threshold and contention probability by using fractional optimization and geometric programming.
AB - We consider a random-access-based ad hoc network, where different links use mini-slots to contend for the channel, and then successful links transmit data packets, as in CSMA. The focus of our study is to develop optimal strategies for physicallayer-aware (PHY-aware) distributed scheduling, which involves a joint process of channel probing and distributed scheduling. Because of channel fading and cochannel interference, the signalto-interference-plus-noise-ratio (SINR) across links is highly dynamic and can exhibit significant variation. In the low SINR case, further channel probing is likely to lead to better SINR conditions and hence yield higher throughput. The desired tradeoff boils down to judiciously choosing the optimal stopping strategy for channel probing before data transmissions. In this paper, we investigate PHY-aware distributed scheduling, aiming to maximize the overall network throughput. The problem under consideration is inherently challenging: 1) multiple links can transmit successfully simultaneously and the number of simultaneously transmitting links is random; and 2) the network throughput is the sum rate of all transmitting links, but each link involved in the transmission has no knowledge of the instantaneous rates of other links, and the stopping decision is made in a distributed manner based on local information only. We use optimal stopping theory to tackle this challenge, and show that the optimal policy for distributed scheduling has a threshold structure. Accordingly, after a channel probing, a link would proceed with data transmissions only if a function of its instantaneous rate is greater than the optimal rate threshold. Observing that the network throughput depends heavily on the contention probability of each link, we generalize the study to jointly optimize the rate threshold and the contention probability, and propose a two-stage algorithm for computing the pair of optimal rate threshold and contention probability by using fractional optimization and geometric programming.
KW - Ad hoc communications
KW - Distributed scheduling
KW - Optimal stopping
KW - Physical interference model
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U2 - 10.1109/TWC.2008.080798
DO - 10.1109/TWC.2008.080798
M3 - Article
AN - SCOPUS:77955754495
SN - 1536-1276
VL - 8
SP - 2682
EP - 2693
JO - IEEE Transactions on Wireless Communications
JF - IEEE Transactions on Wireless Communications
IS - 5
ER -