We discuss the globally optimal energy-efficient design of a 2D relay network. Different from the existing routing protocols on energy saving, which finds the minimal energy route for a given data rate, the proposed algorithm jointly optimizes routing and data rate to maximize energy efficiency (EE) defined as the achievable data rate per power consumption. We propose a low-complexity algorithm to circumvent the huge complexity of the exhaustive search for the network EE maximization and prove its global optimality. Moreover, the proposed algorithm is implemented in a distributed fashion because each relay needs to send its routing information only to the relays in its adjacent tiers, which significantly reduces the signaling overhead of the centralized implementation. Our analysis on the worst-case complexity in a fading channel shows that the complexity of the proposed algorithm increases linearly while that of the exhaustive search increases exponentially as the tier index increases. Simulation results confirm that the proposed algorithm outperforms the existing routing protocols on energy saving and achieves the globally optimal network EE at a significantly lower complexity than the exhaustive search.
Bibliographical noteFunding Information:
Manuscript received April 5, 2017; revised September 29, 2017 and March 12, 2018; accepted August 9, 2018. Date of publication August 28, 2018; date of current version November 9, 2018. This work was supported by the Basic Science Research Program through the National Research Foundation of Korea through the Ministry of Education under Grant 2016R1D1A1A09916968. The associate editor coordinating the review of this paper and approving it for publication was N. Prasad. (Corresponding author: Taewon Hwang.) Y. Kwon was with the School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, South Korea. He is now with the Agency for Defense Development, Daejeon 305-600, South Korea (e-mail: thinggap@ yonsei.ac.kr).
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All Science Journal Classification (ASJC) codes
- Computer Science Applications
- Electrical and Electronic Engineering
- Applied Mathematics