Self organization of tilts in relay enhanced networks: a distributed solution

Imran, A., Imran, M. A. , Abu-Dayya, A. and Tafazolli, R. (2014) Self organization of tilts in relay enhanced networks: a distributed solution. IEEE Transactions on Wireless Communications, 13(2), pp. 764-779. (doi: 10.1109/TWC.2014.011614.130299)

Abstract

Despite years of physical-layer research, the capacity enhancement potential of relays is limited by the additional spectrum required for Base Station (BS)-Relay Station (RS) links. This paper presents a novel distributed solution by exploiting a system level perspective instead. Building on a realistic system model with impromptu RS deployments, we develop an analytical framework for tilt optimization that can dynamically maximize spectral efficiency of both the BS-RS and BS-user links in an online manner. To obtain a distributed self-organizing solution, the large scale system-wide optimization problem is decomposed into local small scale subproblems by applying the design principles of self-organization in biological systems. The local subproblems are non-convex, but having a very small scale, can be solved via standard nonlinear optimization techniques such as sequential quadratic programming. The performance of the developed solution is evaluated through extensive simulations for an LTE-A type system and compared against a number of benchmarks including a centralized solution obtained via brute force, that also gives an upper bound to assess the optimality gap. Results show that the proposed solution can enhance average spectral efficiency by up to 50% compared to fixed tilting, with negligible signaling overheads. The key advantage of the proposed solution is its potential for autonomous and distributed implementation.

• Item Type: Articles
• Additional Information: This work was made possible by NPRP grant No. 5 - 1047 - 2 437 from the Qatar National Research Fund (a member of The Qatar Foundation).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Imran, Professor Muhammad
• Authors: Imran, A., Imran, M. A., Abu-Dayya, A., and Tafazolli, R.
• College/School: College of Science and Engineering > School of Engineering
• Journal Name: IEEE Transactions on Wireless Communications
• Publisher: IEEE
• ISSN: 1536-1276
• ISSN (Online): 1558-2248
• Published Online: 27 February 2014
• Copyright Holders: Copyright © 2014 IEEE
• First Published: First published in IEEE Transactions on Wireless Communications 13(2): 764-779
• Publisher Policy: Reproduced in accordance with the publisher copyright policy