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**Resources and Benchmarks for Dynamic Channel Assignment (DCA) Algorithms**

This work examines the Dynamic Channel Assignment problem (DCA) problem in wireless networks. DCA typically strives to optimize the problem of frequency or channel reuse while maintaining sufficient spatial separability of the wireless systems that transmit on the same channel. This work considers the impact of spatial and temporally varying channel demand functions. Of particular interest is the effect of considering a cumulative interference metric, rather than one based solely on geographic distance. We consider both mathematical programming approaches as well as algorithms that implement heuristics for real-time channel assignment.

This site is created to establish a process for benchmarking the various algorithmic approaches that are presented in the DCA research literature. A taxonomy of approaches presented for solution to this problem and the relevant references is given under published algorithms.

Our basic approach to the problem is presented under the link IP Models and Heuristics.

A method for accelerating the assignment process and investigation into the application towards distributed approaches is given under the shifting strategy link.

**Indoor Wireless Communications**

1. J. Piper and C. Thompson, Fast exact image method for the Sommerfeld half space problem, Argonne symposium for undergraduates in science, engineering and mathematics, Argonne National Lab, Chicago, IL, 2009

2. N. Billong, Threshold amplitude in detection of BPSK signal via simulation, Argonne symposium for undergraduates in science, engineering and mathematics, Argonne National Lab, Chicago, IL, 2009

3. A. Vardaro, A. Bhatta, J. Au, K. Chandra, C. Thompson, Testing the effectiveness of USRP as a channel sounding platform, Argonne symposium for undergraduates in science, engineering and mathematics, Argonne National Lab, Chicago, IL, no. 101, 2008

4. T. Patel, Measuring channel quality using a software defined radio, UMASS Student Research Symposium, UML, 2008

5. P. Sharma and K. Chandra, Prediction of state transition in Rayleigh fading channels, IEEE Trans Vech. Tech.,416-425 2007

6. S. Salahuddin, C. Thompson, and K. Chandra, A New Nonstationary Gaussian Noise Model for Indoor Wireless Channels, MILCOM 2006, 2006

7. C. Thompson, M. Raspopovic, S. Salahuddin, M. Denis, Communication over Indoor Wireless Channels, US Coast Guard Academy, 2006 invited.

8. M. Raspopovic, C. Thompson, K. Chandra. Performance models for wireless spectrum shared by wideband and narrowband sources, Proc. IEEE Milcom, 3, 1642-1647 2005

9. M. Raspopovic and C. Thompson, Ultra-Wide band pulse reflection: Exact image theory, Proc. IEEE Softcom 2005, 2005.

10. M. Denis, V. Vasudevan, K. Chandra and C. Thompson, Characterizing spatial correlation in indoor channels, IEEE Wireless Comm. and Net. Conf, (3) 1850-1855 2004

11. V. Vasudevan, M. Parikh, K. Chandra and C. Thompson, TCP and IEEE 802.11b Protocol performance in indoor wireless channels, Proceedings of IEEE Sarnoff Symposium, 257-261 (2003)

12. M. Parkih, P. Sharma, R, Garg, K, Chandra, C, Thompson, Performance of DS-CDMA protocols in wireless LANS, Proceedings of SPIE, (4865), 213-224 2002

13. P.Sharma, P. Sachetta, K. Chandra, C. Thompson, Channel models for indoor wireless transmission* *, Proceedings of International Conference on Third Generation Wireless and Beyond, 48-52 2001

**Free Space Optical Communications**

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This work examines dispersion caused by diffraction through uniform volume holographic gratings. Of interest is the impact of this dispersion on the spatial and temporal fidelity of an optical communications signal. To this end, a holographic grating is illuminated by a Gaussian beam with 1/e2 diameter large compared to the optical wavelength. Coupled-wave analysis is used to calculate the temporal response of the grating to transmitted symbols encoded in time as a train of Gaussian-shaped pulses. It is shown that temporal dispersion due to diffraction impacts bit-error performance, yielding increased power penalty for larger diffraction angles and beam diameters. Supported by NSF, MIT Lincoln Labs

1. J.M. Tsui, C. Thompson, J.M. Roth, Propagation of data-modulated Gaussian beams through a holographic optical element, Opt. Express, (17) 5556-5570 2009

2. J.M. Tsui, C. Thompson, J.M. Roth, Optical phased array power penalty analysis of apodized, Opt. Express, (15) 5179-5190 2007

3. J. M. Tsui, C. Thompson, V. Metha, J.M. Roth, V.I. Smirnov and L.B. Glebov, Coupled-wave analysis of an apodized volume grating, Proc. SPIE Int. Society Opt Eng. 5970, 59700V 2005

4. J.M. Tsui, C. Thompson, V. Mehta, J.M. Roth, V.I. Smirnov and L.B. Glebov, Coupled-wave analysis of apodized volume gratings, Opt. Express, (12), 6642-6653 2004

**Network Traffic Measurements, Visualization,**

**Analysis & Modeling**

This project examines new models for application and connection level traffic on the Internet. The objective is to better understand the impact of this traffic on network congestion. Features of Internet traffic such as its non- Poisson statistics and long range dependence are a point of departure from typical traffic on circuit switched networks. As packet traffic progresses from the user application to its destination across a network, it undergoes a variety of transformations. These linear and/or nonlinear transformations give rise to structural features in an otherwise random traffic stream. The result is high variability in the network traffic mix. Identifying and controlling the source of these traffic features is important in real-time resource allocation and network traffic engineering. The work in this project uses measured network data to identify the feature space required to model Internet usage. Traffic generation from end users, network protocols and video-coders are considered. Non-linear time-series models will be used to characterize connection and application level traffic. These models have the flexibility to address a range of traffic types from short-range dependent stochastic processes to those with self-similar and deterministic features. At the application level, particular attention is paid to the generation of layered variable bit rate video and into the influence of encoding parameters on traffic characteristics, model parameters and performance. The time-series modeling framework will be used to design optimal rate control algorithms with perceptual and network driven cost constraints. The traffic models obtained will allow one to assess and control end systems and provide network level control for problematic traffic sources. The results will also provide quantitative evaluation of what types of traffic can be superposed to yield suitable statistical multiplexing gains. In conjunction with the research effort, a graduate and undergraduate curriculum in the network performance area will be developed. The courses and projects will support the development of end-to-end problem solving skills. The aim is to integrate research and interdisciplinary ideas from engineering and physical sciences into the solution of telecommunications related problems.