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

Conventional hierarchical modulation (HM) only provides two levels of unequal error protection (UEP) for multimedia traffic transmission. An HM-based scheme is proposed that provides multiple levels of UEP by exploiting the structure of the Alamouti scheme. A typical Alamouti scheme operates based on the assumptions that the modulation scheme used for the transmission at each antenna is the same and that the power in each antenna is equal. In the proposed system, these two operating assumptions are relaxed, in that the modulation schemes as well as the transmission powers for the two antennas are varied in order to propose a multiple level UEP mechanism for multimedia traffic. The concept is applied to a recently proposed system which uses the Alamouti space-time block code (STBC) structure with HM and signal space diversity (SSD), and it is shown via theoretical and simulation results how the simple UEP mechanism can accommodate the simultaneous transmission of multiple classes of multimedia traffic.