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

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.

Simple unequal error protection mechanism for multimedia traffic using the Alamouti structure with hierarchical modulation and signal space diversity

“…The proposed systems in [3][4][5][6] are examples of the first category where HM performance has been enhanced with schemes such as signal space diversity (SSD) and Alamouti space-time block code (STBC). In terms of the second category, the earliest application of HM was for digital broadcasting systems [7,8].…”

“…HM-based systems have been studied extensively and the research work can be broadly summarised into three categories: performance improvement of HM, application of HM to digital broadcasting and the use of HM for UEP in multimedia traffic transmission. The proposed systems in [3][4][5][6] are examples of the first category where HM performance has been enhanced with schemes such as signal space diversity (SSD) and Alamouti space-time block code (STBC). In terms of the second category, the earliest application of HM was for digital broadcasting systems [7,8].…”