Partial HARQ Retransmission For Broadcast In Fading Channels

In this paper, we study the feasibility of a hybrid scheduling approach for broadcast systems in frequency selective fading channels. The hybrid scheduling approach consists of two components: a first broadcast component and a second unicast component. The unicast component is activated if the mobile fails to correctly decode the packet and thus sends back a negative acknowledge to the base station. In this paper, we show that there is an optimal modulation and coding schemeto be used for each one of the components presented. The broadcast optimal modulation and coding scheme depends on the best alignment in fading between different receivers. On the other hand, the unicast optimal modulation and coding scheme depends on the particular fading profile of each mobile separately