TY - JOUR

T1 - Delay-minimal transmission for average power constrained multi-access communications

AU - Yang, Jing

AU - Ulukus, Sennur

N1 - Funding Information:
This work was supported by NSF Grants CCF 04-47613, CCF 05-14846, CNS 07-16311, and CCF 07-29127, and presented in part at the 42nd Asilomar Conference on Signals, Systems and Computers, Pacific Grove, CA, October 2008 [1].

PY - 2010/9

Y1 - 2010/9

N2 - We investigate the problem of minimizing the overall transmission delay of packets in a multi-access wireless communication system, where the transmitters have average power constraints. We use a multi-dimensional Markov chain to model the medium access control layer behavior. The state of the Markov chain represents current queue lengths. Our goal is to minimize the average packet delay through controlling the probability of departure at each state, while satisfying the average power constraint for each queue. We consider a general asymmetric system, where the arrival rates to the queues, channel gains and average power constraints of the two users are arbitrary. We formulate the problem as a constrained optimization problem, and then transform it to a linear programming problem. We analyze the linear programming problem, and develop a procedure by which we determine the optimal solution analytically. We show that the optimal policy has a threshold structure: when the sum of the queue lengths is larger than a threshold, both users should transmit a packet during the current slot; when the sum of the queue lengths is smaller than a threshold, only one of the users, the one with the longer queue, should transmit a packet during the current slot. We provide numerical examples for both symmetric and asymmetric settings.

AB - We investigate the problem of minimizing the overall transmission delay of packets in a multi-access wireless communication system, where the transmitters have average power constraints. We use a multi-dimensional Markov chain to model the medium access control layer behavior. The state of the Markov chain represents current queue lengths. Our goal is to minimize the average packet delay through controlling the probability of departure at each state, while satisfying the average power constraint for each queue. We consider a general asymmetric system, where the arrival rates to the queues, channel gains and average power constraints of the two users are arbitrary. We formulate the problem as a constrained optimization problem, and then transform it to a linear programming problem. We analyze the linear programming problem, and develop a procedure by which we determine the optimal solution analytically. We show that the optimal policy has a threshold structure: when the sum of the queue lengths is larger than a threshold, both users should transmit a packet during the current slot; when the sum of the queue lengths is smaller than a threshold, only one of the users, the one with the longer queue, should transmit a packet during the current slot. We provide numerical examples for both symmetric and asymmetric settings.

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U2 - 10.1109/TWC.2010.062910.081209

DO - 10.1109/TWC.2010.062910.081209

M3 - Article

AN - SCOPUS:77956916942

SN - 1536-1276

VL - 9

SP - 2754

EP - 2767

JO - IEEE Transactions on Wireless Communications

JF - IEEE Transactions on Wireless Communications

IS - 9

M1 - 5510780

ER -