Communication system determining time of arrival using matching pursuit

#The present invention relates to a system and method for determining position of a user terminal or other communication equipment based on time of arrival measurements in a wireless environment.

#Measurements of times of arrival (TOA) for signals from a set of wireless base stations can aid in determining a user's position or location. For example, an LTE (long term evolution) standard receiver can determine its location (or positioning) based on LTE signaling in a way that can replace or supplement GPS or WiFi-assisted positioning strategies.

#The LTE positioning protocol, described for example in ETSI TS 136 355 version 10.0.0, which is referenced in release 10 of the LTE specification, embeds positioning reference signal (PRS) subcarriers into designated orthogonal frequency division multiplexing (OFDM) symbols over specified time intervals, sometimes called positioning occasions. The user equipment (UE) may measure the time of arrival (TOA) of PRS subcarriers from each accessible base station (which the LTE specification calls the eNodeB). The user equipment preferably measures at least one reference signal time difference (RSTD) between two different eNodeBs (one called the reference and the other called the neighbor). The reference signal time difference is related to the established measure for observed time difference of arrival (OTDOA) described in the LTE positioning protocol.

#FIG. 1 is a block diagram of apparatus to perform an observed time difference of arrival (OTDOA) measurement between two base stations using a single antenna receiver.

#FIG. 2 shows a nominal grid of subchannels used in a method for wireless transmission of data and calibration information.

#FIG. 3 shows a functional block diagram to extract the location and estimation pilots from a received sequence of symbols

#Aspects of the present invention provide communication apparatus and communication methods for measuring time of arrival (TOA) at a wireless receiver. A wireless network operating with a preferred wireless receiver according to a given standard may use this time of arrival measuring system to determine the receiver's position. The preferred wireless receiver preferably reacts to symbols designated in accordance with the standard to perform time of arrival measurements. A preferred receiver may, for example, measure time of arrival values and use those values to determine an observed time difference of arrival (OTDOA) between transmitting base stations, which can be transmitted to the network to provide position information relative to the base stations.

#In accordance with other aspects, a system or method preferably may measure time of arrival from a plurality of transmitted pilots, defined as subchannels and having modulation a priori known to the receiver. These transmitted pilots may preferably include pilots or signals other than the location pilot signals specified by the standard for use in measuring time of arrival.

#A preferred implementation of a time of arrival measuring system or method uses one or more strategies for estimating the first path from each designated base station. These strategies may, for example, include applications of iterative matching pursuit (MP) to identify the first path in a wireless channel's impulse response for each transmitting base station assigned to a receiver.