Fair Allocation of Multicast Transmission Costs

In scenarios where many receivers simultaneously are interested in the same data, multicast transmission is more bandwidth efficient than unicast. The reason is that the receivers of a multicast session share the resources through a common transmission tree. Since the resources are shared between the receivers, it is reasonable that the costs corresponding to these resources should be shared as well. This paper deals with fair cost sharing among multicast receivers, and the work is based upon the assumption that costs should be shared according to the resource usage. However, it is not for certain that an optimally fair cost allocation is most beneficial for the receivers; receivers that cannot cover their fair share of the costs may nevertheless be able to contribute to the cost sharing to some extent. We propose a cost-allocation mechanism that strives to allocate the costs fairly, but gives discount to poor receivers who at least manage to cover the additional cost of providing them with the service.