Data networks (2nd ed.)
A framework for opportunistic scheduling in wireless networks
Computer Networks: The International Journal of Computer and Telecommunications Networking
Exploiting medium access diversity in rate adaptive wireless LANs
Proceedings of the 10th annual international conference on Mobile computing and networking
IEEE Transactions on Information Theory
Opportunistic beamforming using dumb antennas
IEEE Transactions on Information Theory
A game-theoretic approach to distributed opportunistic scheduling
IEEE/ACM Transactions on Networking (TON)
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With the convergence of multimedia applications and wireless communications, there is an urgent need for developing new scheduling algorithms to support real-time traffic with stringent delay requirements. However, distributed scheduling under delay constraints is not well understood and remains an under-explored area. A main goal of this study is to take some steps in this direction and explore the distributed opportunistic scheduling (DOS) with delay constraints. Consider a network with M links which contend for the channel using random access. Distributed scheduling in such a network requires joint channel probing and distributed scheduling. Using optimal stopping theory, we explore DOS for throughput maximization, under two different types of average delay constraints: 1) a network-wide constraint where the average delay should be no greater than a; or 2) individual user constraints where the average delay per user should be no greater than αm, m = 1, . . . , M. Since the standard techniques for constrained optimal stopping problems are based on sample-path arguments and are not applicable here, we take a stochastic Lagrangian approach instead. We characterize the corresponding optimal scheduling policies accordingly, and show that they have a pure threshold structure, i.e. data transmission is scheduled if and only if the rate is above a threshold. Specifically, in the case with a network-wide delay constraint, somewhat surprisingly, there exists a sharp transition associated with a critical time constant, denoted by α*. If α is less than α*, the optimal rate threshold depends on α, otherwise it does not depends on α at all, and the optimal policy is the same as that in the unconstrained case. In the case with individual user delay constraints, we cast the threshold selection problem across links as a non-cooperative game, and establish the existence of Nash equilibria. Again we observe a sharp transition associated with critical time constants {αm*}, in the sense that when αm ≥ αm* for all users, the Nash equilibrium becomes the same one as if there were no delay constraints.