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Journal of Electrical and Computer Engineering
Volume 2010, Article ID 316749, 9 pages
http://dx.doi.org/10.1155/2010/316749
Research Article

Hierarchical Modulation with Vector Rotation for E-MBMS Transmission in LTE Systems

Key Laboratory of Universal Wireless Communication, Beijing University of Posts and Telecommunications, Ministry of Education, Xitucheng Road no.10, Haidian District, Beijing 100029, China

Received 1 April 2010; Revised 4 July 2010; Accepted 6 August 2010

Academic Editor: Raymond Kwan

Copyright © 2010 Hui Zhao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Enhanced Multimedia Broadcast and Multicast Service (E-MBMS) is considered of key importance for the proliferation of Long-Term Evolution (LTE) network in mobile market. Hierarchical modulation (HM), which involves a “base-layer” (BL) and an “enhancement-layer” (EL) bit streams, is a simple technique for achieving tradeoff between service quality and radio coverage. Therefore, it is appealing for MBMS. Generally, HM suffers from the severe performance degradation of the less protected EL stream. In this paper, HM with vector rotation operation introduced to EL stream is proposed, in order to improve EL's performance. With the proper interleaving in frequency domain, this operation can exploit the inherent diversity gain from the multipath channel. In this way, HM with vector rotation can effectively enhance multimedia broadcasting on quality video and coverage. The simulation results with scalable video coding (SVC) as source show the significant benefits in comparison with the conventional HM and alternative schemes.