The main objectives of relaying are to extent coverage area and increase throughput without deploying expensive base stations. Mobile multi-hop relay (MMR), which is an amendment of the current mobile WiMAX standard, provides relaying capabilities. WiMAX could be a leading solution to deliver bandwidth-hungry IPTV services to mobile users, due to characteristics such as: multicast support, wide coverage range, high bandwidth and mobility support. The smallest logical bandwidth allocation unit in OFDMA-based WiMAX, is a slot. In this article, we use the term slot to introduce a new performance criterion, called multicast gain, which can be used for computing multicast efficiency. We analyze multicast transmission for delivery of live TV channels in mobile multi-hop relay networks, and determine the gain of access and relay links in order to quantify the benefits of multicasting. This quantification can be used in access control, resource provisioning or decision support mechanisms in delivery of different TV channels in an IPTV system.
