Method and apparatus for increasing accuracy for locating cellular mobile station in urban area

A method for increasing accuracy for locating a cellular mobile station in an urban area, the method comprising the steps of:

• 1) determining whether there is a synchronous measurement request;
• 2) if there is no synchronous measurement request, proceeding to step 4);
• 3) if there is a synchronous measurement request, initiating synchronous measuring management for an assistant locating apparatus, including opening and closing transmission of RTD measuring pilot frequency;
• 4) determining whether there is a locating request;
• 5) if there is no locating request, going to step 1;
• 6) if there is a locating request, determining an approximate location of the mobile station to be located with a time of arrival, TDOA, and sector information of a base station;
• 7) determining whether to open and/or close transmission of a locating pilot frequency from an adjacent assistant locating apparatus according to the approximate location of the mobile station;
• 8) if an assistant locating pilot frequency is opened, measuring the TDOA again, and then determining whether the measurement for the mobile station to be located is completed;
• 9) if the measurement for the locating mobile station is completed, closing transmission of locating pilot frequency from the assistant locating apparatus, and if the measurement for the locating mobile station is not completed, repeating determination of whether the measurement for the locating mobile station is completed;
• 10) searching for and processing multi-paths, identifying NLOS paths according to channel codes of the mobile station to be located, and requesting the assistant locating apparatus to report NLOS path identification result;
• and
• 11) estimating location of the mobile station with measurement of assistant pilot frequency signals and the NLOS path identification result to obtain a more accurate location of the mobile station.

An assistant locating apparatus comprising

• an air interface transmitting/receiving antenna;
• a transmitting/receiving unit B connected to the air interface transmitting/receiving antenna;
• a channel-processing unit B connected to the transmitting/receiving unit B;
• a locating measurement unit-oriented antenna that opens/closes transmission of a RTD measuring pilot frequency;
• a mobile station-oriented transmitting/receiving antenna that opens/closes transmission of an assistant locating pilot frequency;
• a transmitting/receiving unit A that is connected to the locating measurement unit-oriented antenna and the mobile station-oriented transmitting/receiving antenna via a first feed line and a second feed line, respectively, the transmitting/receiving unit A comprises a transmitting unit and a receiving unit, wherein the transmitting unit sends RF signals to the locating measurement unit-oriented antenna and the mobile station-oriented transmitting/receiving antenna independently through symmetric circuits, wherein the channel-processing unit A controls transmission time and modulation mode of the RF signals, wherein the receiving unit comprises a RF filter, a down frequency converter, and a multi-path receiver, and wherein the receiving unit is controlled by the channel-processing unit A and at the same time provides maximum a ratio consolidation output and a multi-path distribution output;
• a channel-processing unit A that comprises a demodulating/decoding unit, an assistant locating pilot frequency or RTD measuring pilot frequency codes-generating unit, an assistant locating pilot frequency transmission control unit, and a RTD pilot frequency transmission control unit;
• a LOS path identification unit that identifies LOS paths and NLOS paths according to the multi-path distribution of LOS paths and NLOS paths;
• a managing unit, which is responsible for communicating with a base station controller and for controlling the LOS path identification unit, channel-processing unit A, and channel-processing unit B.