|Behavioral Modeling of RF and Microwave Circuits|
Circuit designers are faced with the challenge of integrating transceivers for multiple wireless standards with conflicting specifications at increasingly higher frequencies and wider modulation bandwidths. However, it is not currently possible to perform transistor level simulation of a complete integrated radio transceiver within the context of a digital wireless standard. As a result, circuit designers cannot completely verify operation of circuit performance at the system level. New analysis techniques are needed to bridge the gap between circuit simulation and system analysis to permit evaluation of circuit performance at the system level. Behavioral modeling of circuits is a viable alternative to transistor level simulation for verifying system level performance of circuits. However, time to market considerations demand that the amount of time and effort involved in generating a model should be minimized. This raises questions regarding which models and extraction techniques quickly converge to an accurate solution for representing high frequency wideband integrated circuits.
|Target Tracking in Wireless Sensor Networks|
The new trend in military and peacekeeping operations is to use Unattended Ground Sensors (UGS), which use a variety of sensor technologies (including acoustic, seismic, magnetic, electric field, and imaging) to perform remote target detection, tracking, localization and recognition. UGS’s are used in a variety of areas including border surveillance, special force operations, airfield protection, perimeter and building protection, target acquisition, situational awareness, force protection, remote monitoring, and etc. UGS’s improve the ability of tactical units to collect information and are expected to play an increasingly important role in military operations. UGS’s are deployed in the battlefield randomly using different deployment methods (e.g., via aerial deployment) and their detected information is transmitted wirelessly back to monitoring command and control stations, providing real time intelligence data. The deployed sensors are self-organizing to form a multi-hop network. Because of power limitations, UGS’s are required to process data locally, and report only the results of this analysis. Reported data includes the classification, identification and tracking of objects entering the sensor field.
This research focuses on the application of estimation and data fusion techniques to the detection, classification, localization and tracking of targets with unattended ground sensors (UGS). Tracking of multiple targets in a UGS network requires the classification of targets using a set of features extracted from measured data. These features may be taken from different sensors with modalities and hence, a collaborative signal-processing algorithm is needed in order to enhance the target tracking accuracy by combining information from different sensors.
The high peak-to-average power ratio (PAPR) of future wireless communication signals imposes stringent requirements on the linearity of RF units. RF power amplifiers (PA’s) introduce nonlinear distortion if operated in a highly power efficient regimes. Therefore, behavioral modeling of nonlinear power amplifiers is an essential step towards the development linearization schemes to overcome nonlinear distortion. Predistortion is the most common approach because of its simplicity and therefore its lower cost. Predistortion can be implemented at RF, IF or at baseband. Baseband pre-distortion methods are becoming popular because they provide a balanced trade-off between cost and performance.
|Wireless Body Area Networks|
The new vision in health care is to enable the automatic collection of body vital signs from individual patients via Wireless Body Area Networks (WBAN), the integration of this data into a patient's medical record, processing of data, and issuance of recommendations, if necessary. WBAN refers to a set of on-body sensors, actuators and monitoring tools coupled with wireless communication devices that enable continuous monitoring of the vital signs of the patient. A set of wireless sensors pass body data to a main body station (or personal server), which consolidates the data streams of all sensor modules attached. The main station then transmits the data to a health care center through a wireless communication link and the internet where a web portal is used to manage the transfer of data to a remote health care center. Current research on WBAN focuses on the development of new sensors; new radio interfaces new efficient network protocols and new medical software applications that provide Graphical User Interfaces for the interaction of humans with the network.