This thesis is in the context of a Next Generation Network environment formed by two or more distinct wireless access technologies covering a public area. These technologies are administered by different mobile operators, where an end-user terminal can connect to any access technology, through the corresponding wireless interface of that multi-interface terminal. In this emergent network environment, congestion will occur very frequently due to a significant increase in the amount of data traffic crossing the network infrastructure. Consequently, the operators must deploy a deployment strategy to cope with high values of data demand, using the available network resources, without compromising the users' connection quality. The work described in this thesis proposes a distributed brokerage service in the heterogeneous network infrastructure that provides a management solution using cooperative strategy from the mobile operators and allowing the terminals to make well informed decisions for their connections. In this way, a closed management loop among that brokerage service at the network and agents at the mobile terminals counteracts any abnormal traffic load. The brokerage service periodically evaluates each technology, combines both wireless and backhaul status in quality metrics and, disseminates these to the client terminals. Depending on the management policies of the brokerage service, the quality metrics and Service Level Agreements (SLAs), diverse classes of service can be supported across the distinct access technologies. The proposed management distributed algorithm proves to be technically robust and stable, because it performs very satisfactorily in diverse scenarios, supporting different management policies, network loads, user mobility patterns and levels of backhaul provisioning. In addition, the impact of deploying the brokerage service in a real scenario with a dynamic business model was studied. This study concludes that the operator who adopts a deployment strategy of enhancing its network infrastructure can be only rewarded from its initial investment when the brokerage service is in operation. In this way, the market operation becomes fairer.