Cross-Layer Hybrid FEC/ARQ Reliable Multicast With Adaptive Modulation and Coding in Broadband Wireless Networks

In this paper, we define and address a new problem that arises when a base station in a broadband wireless network wishes to multicast information to a large group of nodes and to guarantee some level of reliability using Application-layer forward error correction (FEC) codes. Every data block to be multicast is translated into a sequence of packets, from which every receiver must receive at least in order to correctly decode the block. The new problem is to determine which PHY-layer modulation and coding scheme (MCS) the base station should use for each packet. We present several variants of this problem, which differ in the number of automatic repeat request (ARQ) rounds during which the delivery of a data block must be completed. Most of these variants are shown to be NP-hard. However, we present optimal solutions for practical instances, where the number of MCSs is small, and efficient approximations and heuristics for the general case of each variant.