Evaluation of UML based wireless network virtualization

Virtualization of wireless networks is recognized to be a difficult problem due to the fact that radios interact with their neighbors at various layers of the protocol stack, making strict isolation of virtual networks ("or slices") quite challenging. The goal of virtualization is to support concurrent experiments, both long-running services as well as short-term experiments on shared wireless network. In a wireless network, the radio resources that can be shared and hence virtualized are in time, space and frequency. Efforts have been going on to modify the ORBIT control structure to accommodate different forms of virtualization including VMAC, SDMA, FDMA and TDMA. Among different possible wireless virtualization techniques, this work is focused on allowing a node to run more than one experiment simultaneously using different frequencies i.e. Frequency Division Multiplexing (FDM). Each node in the ORBIT test bed is provided with two physical wireless cards. FDMA virtualization is achieved by running two concurrent User Level Operating Systems (ULOS) on each node and providing each operating system access to a radio card. Thus an experimental end user would view a single node as two virtual nodes, each equipped with one wireless card. Experimental results are provided to compare the performance of a virtualized radio node with the non virtualized one for basic point-to-point experiments using TCP and UDP. Bounds on performance metrics of throughput, delay and jitter are determined and cross-coupling effects between two virtualized experiments are examined. We also look at transient behavior associated with sudden changes in traffic on one of the virtual networks. Finally, the uncertainty in performance measurements for a few typical usage scenarios is investigated, leading to guidelines for use of virtualized radio nodes for simultaneous ORBIT experiments.M.S.Includes bibliographical references (p. 44-45)