Testbed development and performance improvement of heterogeneous radio networks

Within categories of the cognitive radio system used to attain efficient use of restricted radio spectrum resources, this article introduces some technical results concerning cooperative heterogeneous radio networks. We have developed a testbed to affirm the functions of a heterogeneous radio network, which has abilities to select one system from multiple communication systems and to aggregate multiple systems. First of all, we introduce the activities in the ITU-R and DYSPAN, where the cognitive radio system is under discussion, and clarify the standpoint of our research regarding the heterogeneous radio network. Subsequently, we state the function and specification of the testbed developed. Some experimental results using the testbed are introduced. The testbed is composed of three different communication systems, a controlling system for selecting or aggregating the most appropriate system for the user terminal and networks, and its measurement system. The measurement system is a kind of link simulator to confirm the performance of the controlling system. We also describe an analytical example of evaluating the performance improvement by heterogeneous network controlling. Finally, we address some essential future study issues for practical realization of the heterogeneous radio network.