Multi - Interface Wireless Networks

Wireless ad hoc networks typically make use of a single radio interface on a fixed channel to communicate with neighboring nodes. Previous research has advocated the use of multiple wireless channels for enhancing the capacity of such networks. IEEE 802.11 based wireless network interfaces are capable of communicating over multiple frequency separated channels. In existing system architectures the use of multiple channels can be supported provided every channel has one dedicated interface. However, in many scenarios, hosts will be equipped with fewer interfaces than available channels, requiring interfaces to be switched between channels. Implementing protocols, which require frequent switching, is nontrivial. In this thesis, we developed a system that supports the implementation of protocols which require frequent switching. Initially, the feasibility of implementing such protocols using currently available wireless interfaces and system software was studied. The feasibility study identified several shortcomings in present day operating systems for implementing multichannel protocols. We developed a system for the Linux kernel which can handle these shortcomings. Our system includes modifications to the wireless interface device drivers that improve performance of multichannel protocols. We discuss the details of the modifications made to the device driver used in our testbed. Following this, an example multichannel multi-interface protocol interaction with our system is presented. Finally, the performance of our system is analyzed, and suggestions for selecting system parameters are made.