Cross-Layer Power Allocation for Packet Transmission Over Fading Channel

  • Authors:
  • Wei Zhao;Yang Du;Xianmin Zhang

  • Affiliations:
  • Department of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, China 310027;Department of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, China 310027;Department of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, China 310027

  • Venue:
  • Wireless Personal Communications: An International Journal
  • Year:
  • 2012

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Abstract

In this paper, for packet transmission over flat fading channel in single-input-single-output system, we consider the power control problem in a cross-layer design where adaptive modulation is adopted at physical layer to improve spectral efficiency and the queues are modeled as of finite length at data link layer. The goal is to identify the optimal queuing-aware power allocation algorithm to minimize the overall system packet error rate under the constraint of long-term transmit power. One crucial step which we call `inner' problem is to find the optimal power vector at a given target packet error rate at physical layer. Rather than attack the multi-dimensional optimization problem directly using conventional methods, we first observe that the `inner' problem is closely related to an average reward Markov decision process problem, and relax the former to the latter so as to take advantage of its equivalence with linear program which allows efficient solution. Since randomness in the associated Markov decision process is only slight, at most mild, we propose an approximately deterministic policy as suboptimal solution to the `inner' problem with insignificant performance degradation. We also propose two-parameter power allocation functions to achieve suboptimal results with low complexity. The impacts of system parameters on the overall system performance are also evaluated. The accuracy of the numerical result is verified by Monte Carlo simulations.