Apparatus and method for mobile unit positioning

• US 20030003924A1
• Filed: 06/25/2002
• Published: 01/02/2003
• Est. Priority Date: 06/26/2001
• Status: Active Grant

• Current Assignee: BenQ Corporation (Qisda Corporation)
• Original Assignee: BenQ Corporation (Qisda Corporation)
• Inventors: Lin, Tsui-Tsai
• Granted Patent: US 7,139,584 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

An apparatus for mobile positioning and a method therefor are disclosed for determining the location of a mobile unit in a wireless communication system. First, an angle of arrival of a wireless signal transmitted by a mobile unit and being incident on a base station is determined by using an arrival angle estimator including a switched cross-correlator, an accumulator, and a phase detector. Next, the distance between the mobile unit and the base station is estimated according to timing information provided by the base station, such as timing-advance parameter of global system for mobile communications. The mobile unit is then positioned according to the angle of arrival and the distance between the base station and the mobile unit. Mobile positioning can be achieved according to the invention, using one base station without substantially modifying the existing base stations. In addition, the performance of positioning can be significantly improved.

Claims

1. A method of a mobile unit positioning, for using in a base station of a wireless communication system for positioning the mobile unit according to a wireless signal transmitted by the mobile unit, the base station including a first antenna and a second antenna, the first antenna outputting a first communication signal according to the wireless signal and the second antenna outputting a second communication signal according to the wireless signal, the method comprising the steps of:

transmitting the wireless signal by the mobile unit;

calculating a distance between the mobile unit and the base station according to timing information provided by the base station;

(a) calculating an angle of arrival which the wireless signal makes with respect to the base station, according to the first communication signal and the second communication signal; and

positioning the mobile unit according to the angle of arrival and the distance.

2. The method according to claim 1, wherein said step (a) comprises the steps of:

performing a cross-correlation operation of the first communication signal and the second communication signal to calculate a cross-correlation parameter; and

determining the angle of arrival according to the cross-correlation parameter and a relative position between the first antenna and the second antenna.

3. The method according to claim 1, wherein said step (a) comprises the steps of:

setting a count value to m;

setting a parameter p to zero;

(b) receiving the first communication signal during a time period (2k);

(c) receiving the second communication signal during a time period (2k+1);

(d) calculating a cross-correlation parameter by a performing cross-correlation operation of the first communication signal and the second communication signal; and

(e) obtaining the sum of the parameter p and the cross-correlation parameter as a sum parameter and setting the value of the parameter p to the sum parameter;

(f) determining whether k is less than m;

if so, adding 1 to k and proceeding to said step (b);

(g) generating an average cross-correlation parameter according to the sum parameter; and

(h) determining the angle of arrival according to the average cross-correlation parameter and the relative position of the first antenna and the second antenna;

wherein k and m are integers.

4. An arrival angle estimator for determining an arrival angle, the arrival angle being an incident angle of a radio signal from a mobile unit with respect to a base station, the base station including a first antenna and a second antenna, the first antenna being used for receiving the radio signal and producing a first communication signal according to the radio signal received by the first antenna, the second antenna being used for receiving the radio signal and producing a second communication signal according to the radio signal received by the second antenna, the arrival angle estimator comprising:

a switched cross-correlator for receiving the first communication signal and the second communication signal in a time-switching manner, performing a cross-relational operation on the first communication signal and the second communication signal, and outputting a plurality of cross-correlation parameters;

an accumulator, coupled to the switched cross-correlator, for receiving the cross-correlation parameters and outputting an average of the cross-correlation parameters according to the cross-correlation parameters; and

a phase detector, coupled to the accumulator, for receiving the average of the cross-correlation parameters and outputting an arrival angle according to the average of the cross-correlation parameters.

5. The arrival angle estimator according to claim 4, wherein the switched cross-correlator comprising:

a multiplexer for receiving the first communication signal and the second communication signal and outputting a multiplexed signal; and

a multiplication unit coupled to the multiplexer for receiving the multiplexed signal and outputting the plurality of the cross-correlation parameters according to the multiplexed signal.

6. The arrival angle estimator according to claim 5, wherein the multiplexer according to a clock signal alternately selects one of the first communication signal and the second communication signal as a selected communication signal, and outputs the multiplexed signal according to the selected communication signal.

7. The arrival angle estimator according to claim 4, wherein the multiplication unit, according to the clock signal, performs multiplication of the multiplexed signal during a kth time period and the multiplexed signal during a k+lth time period and outputs the product thereof as one of the cross-correlation parameters.

8. A locating method for using in a wireless communication system, the locating method comprising the steps of:

determining a distance between a mobile unit and a base station, based on timing information from the mobile unit;

calculating an arrival angle of a radio signal from the mobile unit according to the radio signal from the mobile unit, wherein the arrival angle is the incident angle of the radio signal with respect to the base station;

determining a location of the mobile unit, based on the distance and the arrival angle.

9. The method according to claim 8, wherein the base station includes a first antenna and a second antenna, the first antenna is used for receiving the radio signal and producing a first communication signal according to the radio signal, the second antenna is used for receiving the radio signal and producing a second communication signal according to the radio signal, and the base station determines the arrival angle by calculating a cross-correlation parameter according the first communication and the second communication signal.