Cooperative Localization in Wireless Ad Hoc and Sensor Networks

The need for highly accurate position information is of great importance in many commercial, public safety, and military applications. With the integration of GPS into cell phones, in conjunction with WiFi localization, we are entering a new era of ubiquitous location-awareness. In the coming years, we will see the emergence of high-definition location-awareness applications: localization systems that operate in the harsh communication environments where GPS does not operate, such as inside buildings and in caves, still providing submeter localization accuracy which is not currently feasible with GPS. Reliable localization in such conditions is a key enabler for a wide variety of applications including logistics, security tracking (the localization of authorized persons in high-security areas), medical applications (the monitoring of patients), search and rescue (communications with fire fighters or natural disaster victims), control of home appliances, automotive safety, and military systems, as well as in the large set of emerging wireless sensor network (WSN) applications. Other nonconventional applications of location information include networking protocols that take advantage of position information to improve the performance of routing algorithms (georouting), as well as enabling interference avoidance techniques in future cognitive radios. One of the major requirements for most applications based on wireless ad hoc and sensor networks is accurate node localization even in the absence of infrastructure (anchor nodes). In fact, sensed data without position information is often less useful. Due to several factors (e.g., cost, size, power) only a small fraction of nodes obtain the position information of the anchor nodes. In this case, a node has to estimate its position without a direct interaction with anchor nodes; and a cooperation between nodes is needed in a multihop fashion. In some applications none of the nodes is aware of its absolute position (anchor-free) and only relative coordinates are estimated instead. Whether the localization techniques are based on signal strength or on signal time-of-flight, measurement errors are unavoidable, especially in cluttered environments. Robust estimation signal processing schemes as well as cooperative localization algorithms are useful to improve localization accuracy. The goal of this special issue is to bring together contributions from signal processing, communications, and related communities, with particular focus on fundamental limitations, signal processing, and new algorithm design methodologies of cooperative localization systems. The understanding of fundamental localization performance limits in cooperative networks in the presence of unreliable measurements is of great importance since the knowledge of such limits can also help …