TY - JOUR
T1 - Distributed opportunistic scheduling for ad hoc communications with imperfect channel information
AU - Zheng, Dong
AU - Pun, Man On
AU - Ge, Weiyan
AU - Zhang, Junshan
AU - Poor, H.
N1 - Funding Information:
Manuscript received December 5, 2007; revised June 19, 2008; accepted August 3, 2008. The associate editor coordinating the review of this paper and approving it for publication was T. Hou. This research was supported in part by the Croucher Foundation under a post-doctoral fellowship, by the U. S. National Science Foundation under Grants ANI-02-38550, ANI-03-38807, CNS-06-25637 and CNS-07-21820, and by an ONR Young Investigator Award through Grant N00014-05-1-0636. This work was presented in part at the 2008 IEEE International Conference on Communications, Beijing, China, May, 2008.
PY - 2008/12
Y1 - 2008/12
N2 - Distributed opportunistic scheduling is studied for wireless ad-hoc networks, where many links contend for one channel using random access. In such networks, distributed opportunistic scheduling (DOS) involves a process of joint channel probing and distributed scheduling. It has been shown that under perfect channel estimation, the optimal DOS for maximizing the network throughput is a pure threshold policy. In this paper, this formalism is generalized to explore DOS under noisy channel estimation. In such cases, the transmission rate needs to be backed off from the estimated rate to reduce outages. It is shown that the optimal scheduling policy remains threshold-based, and that the rate threshold turns out to hinge on the variance of the estimation error and be a functional of the backoff rate function. Since the optimal backoff rate is intractable, we devise suboptimal linear backoff schemes that back off the estimated signal-to-noise ratio (SNR) and hence the rate. The corresponding optimal backoff ratios and rate thresholds can be obtained via iterative algorithms. Finally, simulation results are provided to illustrate the tradeoff between increased training time to improve channel estimation and probing efficiency.
AB - Distributed opportunistic scheduling is studied for wireless ad-hoc networks, where many links contend for one channel using random access. In such networks, distributed opportunistic scheduling (DOS) involves a process of joint channel probing and distributed scheduling. It has been shown that under perfect channel estimation, the optimal DOS for maximizing the network throughput is a pure threshold policy. In this paper, this formalism is generalized to explore DOS under noisy channel estimation. In such cases, the transmission rate needs to be backed off from the estimated rate to reduce outages. It is shown that the optimal scheduling policy remains threshold-based, and that the rate threshold turns out to hinge on the variance of the estimation error and be a functional of the backoff rate function. Since the optimal backoff rate is intractable, we devise suboptimal linear backoff schemes that back off the estimated signal-to-noise ratio (SNR) and hence the rate. The corresponding optimal backoff ratios and rate thresholds can be obtained via iterative algorithms. Finally, simulation results are provided to illustrate the tradeoff between increased training time to improve channel estimation and probing efficiency.
KW - Ad hoc networks.
KW - Channel Estimation
KW - Distributed opportunistic scheduling
KW - Optimal stopping theory
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U2 - 10.1109/T-WC.2008.071368
DO - 10.1109/T-WC.2008.071368
M3 - Article
AN - SCOPUS:58149133565
SN - 1536-1276
VL - 7
SP - 5450
EP - 5460
JO - IEEE Transactions on Wireless Communications
JF - IEEE Transactions on Wireless Communications
IS - 12
M1 - 4723354
ER -