## Hardware

#### 802.15.4 Radio Standard

**[Callaway02]**: Ed Callaway, Paul Gorday, Lance Hester, Jose A. Gutierrez, Marco Naeve, Bob Heile, and Venkat Bahl, "Home Networking with IEEE 802.15.4: A Developing Standard for Low-Rate Wireless Personal Area Networks," *IEEE Communications Magazine*, August 2002, pages 70-77. Online: http://www.coe.uncc.edu/~jmconrad/ECGR6090-2004-01/notes/TG4%20Comm%20Paper.pdf

#### TinyOS programming

**[Levis06]**: Philip Levis, *TinyOS Programming*, Online: http://csl.stanford.edu/~pal/pubs/tinyos-programming-1-0.pdf, June 28, 2006, 139 pages. Notes: A helpful resource for those of us involved in TinyOS programming.

## Overviews

**[Patwari05]**: N. Patwari, J. Ash, S. Kyperountas, A. O. Hero, R. M. Moses, N. S. Correal, "Locating the Nodes: Cooperative Localization in Wireless Sensor Networks", *IEEE Signal Processing Magazine*, special issue on Signal Processing in Positioning and Navigation, vol. 22, no. 4, July 2005, pp. 54-69. Online: http://www.ece.utah.edu/~npatwari/pubs/localizationMag.pdf. Notes: Just a general overview of range and angle measurement, and localization algorithm research.

**[Akyildiz02]**: I. F. Akyildiz, W. Su, Y. Sankarasubramaniam, E. Cayirci, *Computer Networks (Elsevier)*, Volume 38, Issue 4, 15 March 2002, Pages 393-422. Online: http://www.cs.umn.edu/research/mobile/seminar/FALL04/WNfiles/sensornets.pdf. Notes: A very long, but complete review of wireless sensor network research.

## Angle-of-arrival

#### Statistical models for AOA

**[Abdi02]**: Abdi, A.; Barger, J.A.; Kaveh, M. "A parametric model for the distribution of the angle of arrival andthe associated correlation function and power spectrum at the mobile station," *IEEE Transactions on Vehicular Technology*, Volume 51, Issue 3, May 2002, Pages: 425 - 434. Online: http://web.njit.edu/~abdi/T_VT_NonIsoCorrSpec_revised.pdf. Notes: This paper describes a model for angle of arrival at a receiver called the "von Mises angular distribution", which, in the log power scale, is proportional to a cosine, with peak at the mean direction of arrival. This distribution can be used to justify our approach of finding the main AOA by matching the received power vs. angle profile with a cosine.

**[Anderson02]**: Andersen, J.B.; Pedersen, K.I. "Angle-of-arrival statistics for low resolution antennas," *IEEE Transactions on Antennas and Propagation,* Volume 50, Issue 3, Mar 2002, Pages: 391 - 395. Online: http://kom.aau.dk/~pe/education/phd/litt/JBA_AP2002.pdf. Notes: This paper is a typical paper discussing statistics of angle-of-arrival. It uses a phased-array antenna. Arriving power is closely centered around the correct line-of-sight path. But this paper is for radar applications like detecting and locating planes by scattering of EM waves; the antenna is outdoors, looking at the sky, and thus doesn't experience any significant multipath problems.

**[Spencer97]**: Quentin Spencer, Michael Rice, Brian Jeffs, Michael Jensen. "A statistical model for angle of arrival in indoor multipath propagation," in Proc. of the *IEEE Vehicular Technology Conference (VTC ’97)*, Phoenix, Arizona, 1997, pages 1415--1419. Online: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.56.4072. Notes: This paper discusses measurements which characterize *both* time-of-arrival and angle-of-arrival, and it comes up with a statistical model for both simultaneously. But for our purposes, they describe the pdf of AOA as a triangle, with the maximum at the main direction of arrival. They show measurements that have an AOA standard deviation of 25.5 and 21.5 degrees, in two different buildings.

#### AOA measurement methods

**[Schmidt86]**: Schmidt, R. "Multiple emitter location and signal parameter estimation," *IEEE Transactions on Antennas and Propagation,* March 1986, Volume: 34, Issue: 3, pages 276-280. Online in IEEExplore (requires access permission, get it through lib.utah.edu: http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1143830. Notes: This is a classic paper which provides a spectral method for estimating angle-of-arrival from a phased-array antenna.

**[Durgin00]**: Durgin, G.D.; Rappaport, T.S. "Theory of multipath shape factors for small-scale fading wireless channels," *IEEE Transactions on Antennas and Propagation*, Volume: 48, Issue: 5, May 2000, pages 682-693. Online: http://www.propagation.gatech.edu/Archive/PG_WA_040906_GDD/RParchive/TransAP00.pdf. Notes: This paper provides some theory about how the Fourier series of the angular power profile is important. In particular, how the first and second Fourier series components can be used to describe the direction and width of the AOA measurement.

**[Ash04]**: J. N. Ash and L. C. Potter, “Sensor network localization via received signal strength measurements with directional antennas,” in Proceedings of the 2004 Allerton Conference on Communication, Control, and Computing, 2004. Online: http://www.ece.osu.edu/~ashj/pubs/allerton04.pdf. Notes: This paper uses a method like ours, measuring RSS using directional antenna measurements. In this paper, the antenna is pointed in one of a few (on the order of 2-4) directions. In ours, we're measuring RSS while the directional antenna is rotated to many many directions. Last year's clinic attempted to implement this method directly. However, it didn't work as well as it did in this paper, largely because indoor multipath caused big errors. Our method should be more robust to multipath.

## Localization Algorithms

**[Niculescu03]** Niculescu, D.; Nath, B. "Ad hoc positioning system (APS) using AOA," in Proceedings of the *IEEE Twenty-Second Annual Joint Conference of the IEEE Computer and Communications Societies (INFOCOM 2003)*, April 2003, Volume 3, pages: 1734- 1743. Online: http://www.cs.rutgers.edu/dataman/papers/infocom03-dragos.pdf. Notes: This paper provides a localization algorithm assuming that all nodes have AOA-measurement capability. It will be important to find out in this paper what it assumes about the accuracy of AOA measurements.

**[Rong06]**: Rong, P; Sichitiu, M.L. "Angle of Arrival Localization for Wireless Sensor Networks," in Proceedings of the *2006 IEEE 3rd Annual IEEE Communications Society on Sensor and Ad Hoc Communications and Networks, 2006 (SECON '06)*, 28-28 Sept. 2006, Volume: 1, pages 374-382. Online: http://www4.ncsu.edu/~mlsichit/Research/Publications/aoaLocalizationSecon06.pdf. Notes: This paper provides a probabilistic method for localization using AOA measurements which is more general than the [Niculescu03] algorithm.

**[Costa06]**: J. A. Costa, N. Patwari, A. O. Hero, "Distributed Weighted Multidimensional Scaling for Node Localization in Sensor Networks", *ACM Transactions on Sensor Networks*, Feb. 2006, vol. 2, no. 1, pp. 39-64. Online: http://www.ece.utah.edu/~npatwari/pubs/wmds.pdf. Notes: This paper presents the theory of the algorithm which uses RSS to do distributed localization of the nodes. This is the algorithm implemented in our DWMDS sensor network program.

**[Patwari03]**: N. Patwari, A. O. Hero, M. Perkins, N. S. Correal, R. J. O'Dea, "Relative Location Estimation in Wireless Sensor Networks", *IEEE Transactions on Signal Processing*, vol. 51, no. 8, August 2003, pp. 2137-2148. Online: http://www.ece.utah.edu/~npatwari/pubs/patwari03-print.pdf. Notes: This presents a maximum-likelihood algorithm to locate sensors using pair-wise RSS measurements. This is a centralized algorithm. Maximum likelihood is a style of algorithm that is general enough that we could use it with AOA measurements as well.

## Demonstrations / Implementations

**[Patwari06]**: N. Patwari, P. Agrawal, A. O. Hero, "Demonstrating Distributed Signal Strength Location Estimation", in *Proceedings of the Fourth Int. Conf. on Embedded Networked Sensor Systems (SenSys'06)*, Boulder, CO, Nov. 1-3, 2006, pp. 353-354. Online: http://www.ece.utah.edu/~npatwari/pubs/sensys06-patwari.pdf. (Poster and Video Clip 1, Clip 2, and Clip 3) Notes: This is a short description of the live demonstration we did using RSS-only distributed localization.