This paper describes the design and implementation of a network virtualization substrate (NVS) for effective virtualization of wireless resources in WiMAX networks. Virtualization fosters the realization of several interesting deployment scenarios such as customized virtual networks, virtual services and wide-area corporate networks, with diverse performance objectives. In virtualizing a basestation’s uplink and downlink resources into slices, NVS meets three key requirements—isolation, customization, and efficient resource utilization—using two novel features: (1) NVS introduces a provably-optimal slice scheduler that allows existence of slices with bandwidth-based and resource-based reservations simultaneously, and (2) NVS includes a generic framework for efficiently enabling customized flow scheduling within the basestation on a per-slice basis. Through a prototype implementation and detailed evaluation on a WiMAX testbed, we demonstrate the efficacy of NVS. For instance, we show for both downlink and uplink directions that NVS can run different flow schedulers in different slices, run different slices simultaneously with different types of reservations, and perform slice-specific application optimizations for providing customized services.

Programmable consumer devices have placed computation within arm’s reach at all times and in all places. Unfortunately, researchers interested in investigating this phenomenon often struggle with the expense, inconvenience, and limited scale of existing experimental platforms. In this paper, we introduce a new experimental platform for mobile and pervasive computing based on JellyNets, an abstraction for exposing experiments to arbitrary mobile social contexts. 1.

Abstract. In IEEE 802.11 networks composed by multiple APs, before a station can access the network it needs to make a decision about which AP to associate with. Usually, legacy 802.11 stations use no more than the signal strength of the frames received from each AP to support their decision. This can lead to an unbalanced distribution of stations among the APs, causing performance and unfairness problems. This work proposes a new approach that combines the number of associated stations and the current load of each AP plus the virtualization of client wireless interfaces. In this approach, stations permanently switch of association among the APs, staying on each AP for a time that takes into account the number of associated stations and the current load in each AP. Simulation results confirm the improvement obtained in the load balancing and fairness on network capacity allocation, while keeping the maximum network utilization. Key words: wireless networks, scheduling, 802.11, association 1

Abstract—Laboratory-based mobile wireless testbeds such as MeshTest and the CMU Wireless Emulator are powerful platforms that allow users to perform controlled, repeatable, mobile wireless experiments in the lab. Unfortunately such systems can only accommodate 10-20 nodes in an experiment. We have designed and built a prototype of a system that uses software virtualization and live migration to facilitate experiments involving intermittently connected networks with many multiples of the number of physical nodes available on such a testbed. Building a system like this presents many technical and research challenges. In this paper, we will describe the physical construction and software architecture of the system while providing a discussion on the research issues that we are currently addressing. I.

Due to the existence of multiple stakeholders with conflicting goals and policies, alterations to the existing Internet are now limited to simple incremental updates; deployment of any new, radically different technology is next to impossible. To fend off this ossification once and for all, network virtualization has been propounded as a diversifying attribute of the future inter-networking paradigm. By allowing multiple heterogeneous network architectures to cohabit on a shared physical substrate, network virtualization provides flexibility, promotes diversity, and promises security and increased manageability. In this paper, we present a network virtualization model with a set of quintessential design goals, survey the past and the state-of-the-art of network virtualization, and discuss the future challenges that must be addressed to realize a viable network virtualization model. 1

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