This is the fourth in the series of CAMSAP workshops, and like the other meetings in the series, CAMSAP 2011 is brimming with high quality papers at the cutting edge of the signal processing discipline. The lure of the warm sunny beaches of Puerto Rico has attracted submissions from many of the top signal processing researchers in the world, and we have done our best to put together a stimulating technical program that will provide you with fresh new perspectives on the field. With sessions on topics from MIMO radar to smart power grids, financial engineering to geolocation and cognitive radios to compressive sensing, there is something here for everyone interested in signal processing.

We express special thanks to the organizers of our eleven special sessions: Dan Fuhrmann, Daniel Palomar, Francisco Rubio, Pascal Larzabal, Arye Nehorai, Petar Djurić, Georgios Giannakis, Seung-Jun Kim, Geert Leus, Usman Khan, Aylin Yener, Martin Haardt, Eleftherios Karipidis, Volkan Cevher and Andrea Montanari. We couldn't have asked for a better set of session topics and speakers, and we appreciate their efforts in setting up the sessions and obtaining timely reviews of their papers. In addition, we had a large number of excellent regular paper submissions that have rounded out the program in several important technical areas. We also wish to thank the many reviewers who provided feedback on both the invited and regular papers; the CAMSAP Technical Program Committee handled the bulk of these reviews, and we are grateful for their prompt and expert opinions. We gratefully acknowledge the generous financial support of the [http://www.onr.navy.mil|U.S. Office of Naval Research], which sponsored our student travel grants and lower student registration fees.

Finally, we wish to recognize the special contributions of our dear friend and colleague Alex Gershman, who passed away a few months prior to the workshop. Alex was instrumental in organizing the CAMSAP workshop series, and his friendly and enthusiastic presence will be sorely missed. We dedicate this year's meeting to his memory.

Hope you enjoy the workshop!

Lee Swindlehurst and Sergiy Vorobyov Technical Program Chairs

{img src=images/ls.jpg height=100 class=photo-left desc=Swindlehurst}{img src=images/sergiy.jpg height=100 class=photo-left desc=Vorobyov}