Mutli-homing radio resource allocation is considered to be a promising solution that can efficiently exploit the available resources in a heterogeneous wireless access medium to satisfy required QoS, reduce call blocking probability, and enhance mobility support. The main challenge in designing a multi-homing resource allocation algorithm is how to coordinate the allocation from different networks so as to satisfy the user’s target QoS while making efficient utilization of available network resources. One simple solution is to employ a central resource manager with a global view over the available resources and the calls required QoS, that can perform the necessary coordination among different networks. However, this solution is not practical in the case that those different networks are operated by different service providers. Hence, the question now is how to coordinate the resource allocation in different networks without a central resource manager. In addition, it is more practical that every network prioritize resource allocation to its own subscribers as compared to other users. In this chapter, we present a decentralized optimal radio resource allocation mechanism that enables each MT to coordinate the resource allocation from different networks to satisfy its target QoS, and allows each network to give a higher priority in allocating its resources to its own subscribers. We first present the system model under consideration, then discuss the problem formulation for the decentralized resource allocation.