Person:

Murty, Rohan

Wireless spectrum is a valuable and scarce resource that currently suffers from under-use because of the dominant paradigm of exclusive-use licensing. We propose the SATYA auction (Sanskrit for truth), which allows short-term leases to be auctioned and supports diverse bidder types, including those willing to share access and those who require exclusive-use access. Thus, unlike unlicensed spectrum such as Wi-Fi, which can be shared by any device, and exclusive-use licensed spectrum, where sharing is precluded, SATYA improves efficiency through supporting sharing alongside quality-of-service protections. The auction is designed to be scalable, and also strategy proof, so that simple bidding protocols are optimal. The primary challenge is to handle the externalities created by allocating shared-use alongside exclusive-use bidders. Using realistic Longley-Rice based propagation modeling and data from the FCC’s CDBS database, we conduct extensive simulations that demonstrate SATYA’s ability to handle heterogeneous bidders involving different transmit powers and spectrum needs.

In this paper, we present the vision for an open, urban-scale wireless networking testbed, called CitySense, with the goal of supporting the development and evaluation of novel wireless systems that span an entire city. CitySense is currently under development and will consist of about 100 Linux-based embedded PCs outfitted with dual 802.11a/b/g radios and various sensors, mounted on buildings and streetlights across the city of Cambridge. CitySense takes its cue from citywide urban mesh networking projects, but will differ substantially in that nodes will be directly programmable by end users. The goal of CitySense is explicitly not to provide public Internet access, but rather to serve as a new kind of experimental apparatus for urban-scale distributed systems and networking research efforts. In this paper we motivate the need for CitySense and its potential to support a host of new research and application developments. We also outline the various engineering challenges of deploying such a testbed as well as the research challenges that we face when building and supporting such a system.

As wireless local area networks (WLANs) continue to evolve. the fundamental division of responsibility between the access point (AP) and the client has remained unchanged. In most cases, clients make independent decisions about associations and packet transmissions, using only locally available information. Furthermore, the IEEE 802.11 standard defines a very limited interface for transferring information between the APs and the clients. These factors impede customization of WLANs to meet site-specific challenges, and in a more general sense, impede rapid innovation to face challenges posed by new applications such as VoIP. This paper describes Dyson, an extensible architecture for WLANs, targeted primarily at enterprise scenarios. Our architecture is based on centralized, global management of channel resources. To provide extensibility, the interface between the infrastructure and clients is simple and relatively low-level, and can be controlled through a programmatic interface. Clients provide primitives that allow the central controller to control many aspects of client behavior. The controller can also instruct clients to gather and report information about channel conditions. We show that using these simple primitives, and by leveraging historical information, the network designer can easily customize many aspects of the WLAN behavior. We have built a prototype implementation of Dyson, which currently runs on a 23-node testbed distributed across one floor of a typical academic building. Using this testbed, we examine various aspects of the architecture in detail, including a range of policies for improving client-AP associations, providing user-specific airtime reservations, mitigating the effects of interference, and improving mobile handoffs. We show that Dyson is effective at providing greater efficiency while opening up the network to site-specific customizations.

Wireless spectrum is a scare resource, but in practice much of it is under-used by current owners. To enable better use of this spectrum, we propose an auction approach to dynamically allocate the spectrum in a secondary market. Unlike previous auction approaches, we seek to take advantage of the ability to share spectrum among some bidders while respecting the needs of others for exclusive use. Thus, unlike unlicensed spectrum (e.g. Wi-Fi), which can be shared by any device, and exclusive-use licensed spectrum, where sharing is precluded, we enable efficient allocation by supporting sharing alongside quality-of-service protections. We present SATYA (Sanskrit for “truth”), a strategyproof and scalable spectrum auction algorithm whose primary contribution is in the allocation of a right to contend for spectrum to both sharers and exclusive-use bidders. Achieving strategyproofness in our setting requires appropriate handling of the externalities created by sharing. We demonstrate SATYA’s ability to handle heterogeneous agent types involving different transmit powers and spectrum needs through extensive simulations.