Coherent acoustic array processing and localization on wireless sensor networks

Advances in microelectronics, array processing, and wireless networking have motivated the analysis and design of low-cost in-tegrated sensing, computing, and communicating nodes capable of performing various demanding collaborative space–time pro-cessing tasks. In this paper, we consider the problem of coherent acoustic sensor array processing and localization on distributed wireless sensor networks. We first introduce some basic concepts of beamforming and localization for wide-band acoustic sources. A re-view of various known localization algorithms based on time-delay followed by least-squares estimations as well as the maximum–like-lihood method is given. Issues related to practical implementation of coherent array processing, including the need for fine-grain time synchronization, are discussed. Then we describe the implemen-tation of a Linux-based wireless networked acoustic sensor array testbed, utilizing commercially available iPAQs with built-in micro-phones, codecs, and microprocessors, plus wireless Ethernet cards, to perform acoustic source localization. Various field-measured re-sults using two localization algorithms show the effectiveness of the proposed testbed. An extensive list of references related to this work is also included. Keywords—Ad hoc network, beamforming, distributed sensor network, microphone array, source localization, time synchroniza-tion, wireless network. I