April 9, 2008: A Dynamic Spectrum Access Protocol for Single-Radio Wireless Ad Hoc Networks
1-2pm, Cory 258
Dr. Liangping Ma from Network Systems Divison, Argon ST, Inc.
We present the Single-Radio Adaptive Channel (SRAC) dynamic spectrum access (DSA) protocol for wireless Ad Hoc networks consisting of single-radio nodes. The SRAC protocol consists of four parts: adaptive channelization, channel selection, channel rendezvous, and reliable data transmission. In traditional wireless networks, the spectrum is partitioned into fixed channels, and the channel that a node can use is often fixed. This imposes a stringent constraint on the usability of available spectrum. With adaptive channelization, spectrum is partitioned into atomic channels, and they can be combined to form composite channels that better utilize the available spectrum. The channel selection algorithm allows nodes to determine the amount of spectrum to use based on the communication needs, and it also supports efficient wireless multicast. The channel rendezvous algorithm allows each node to find its neighbors' new channels when nodes independently change their channels in response to jamming or primary spectrum user activities. The channel rendezvous algorithm is distributed, does not rely on a common control channel, and incurs low communication overhead. The reliable data transmission algorithm is a multi-channel RTS/CTS type of ARQ mechanism. Simulation results show the effectiveness of the SRAC protocol.
Feb 2008
February 29, 2008: Cognitive Wireless Networking in the TV Bands
2-3pm, Cory 400
Dr. Ranveer Chandra from Microsoft Research
The FCC has announced that its willingness to consider the operation of unlicensed devices in the TV bands. Compared to the ISM bands, this portion of the spectrum has several desirable properties for robust data communications. However, to make efficient use of this spectrum in a way that is non-disruptive to incumbents, there are a number of challenges that must be handled. For example, an unused portion of the spectrum must be found, and it is likely that its availability will vary over time. To address such challenges, we have developed a hardware-software platform that includes a spectrum-aware Medium Access Control (MAC) protocol and algorithms to deal with spectrum fragmentation. In this talk, I will describe our prototype and some early evaluation results.
February 22, 2008: Harnessing whitespace: opportunites, challenges, and case studies
2-3pm, BWRC
Dr. Jianfeng Wang from Philips Research North America
Federal Communications Commission (FCC) has taken a number of important steps towards allowing the license-exempt use of spectrum white spaces. With the innovation of cognitive radio (CR), this plan will significantly facilitate new types of devices and services, without disrupting television and other authorized services using the TV bands. The aim of this talk is to review the recent progress in addressing the various aspects of cognitive radio networks for the license-exempt use of TV bands. This talk will cover recent relevant regulation, technical challenges pertaining to communications and networking protocols, and present some case studies for Cognitive Radios in TV bands.