Receiver Architecture for Cognitive Positioning with CDMA and OFDM signals

Abstract

This paper proposes a cognitive positioning architecture to determine which signals are present in the surrounding spectrum of a receiver. These signals are used by the cognitive positioning engine to acquire time of arrival measurements. The spectrum content is determined by a cyclostationary method and this information is used by the cognitive positioning engine to retrieve information from the adequate loops. This architecture provides a fast mechanism to infer the contents of the spectrum and improve the efficiency of the resources by allowing the cognitive positioning engine to control the acquisition and tracking loops. The performance of the spectrum sensing and positioning blocks is evaluated by considering the presence of CDMA and OFDM signals. First, the spectrum sensing block is evaluated using different input scenarios, such as presence of both, one or only noise. Cyclostationary features are used to classify the spectral contents and derive a probability of detection for each scenario. Second, the performance level of the cognitive positioning engine is discussed by considering an hypothetical scenario where several CDMA and OFDM emitters are used for determining the position of an user through a maximum likelihood approximation method.