Performance Analysis of Two Cooperative Multicast Schemes in Cellular Networks

This paper discusses multicast schemes in cellular networks based on rateless codes and cooperative relaying technologies. Unlike fixed-rate codes, rateless codes do not require channel state information at transmitters or feedback of successful reception of individual packets from recipient user equipment (UEs). Cooperative relaying among a group of multicast recipient UEs can further improve wireless multicast service. In the proposed cooperative multicast (CM) scheme, after part of the recipients have decoded the source message of the base station (BS), these recipients can act as cooperative relays (CRs) and simultaneously transmit the decoded information to other recipients. The CM process stops after all the recipients have reliably decoded the message. If the CRs use different fountain codes, the other recipients can accumulate the mutual information from the BS and the CRs. If the CRs use the same fountain code as used by the BS, the recipients can only accumulate the received energy. By comparing with the conventional direct transmission based multicast scheme, the transmission delay, the energy consumption, and the spectrum efficiency performances of the proposed CM schemes are evaluated. The simulation results show that the mutual information accumulation (MIA) based CM scheme outperforms the energy accumulation (EA) based CM scheme in the spectrum and energy efficiency. This is because the MIA approach acquires better time delay performance but consumes less energy than the EA approach.