RF signal repeater, mobile unit position determination system using the RF signal repeater, and method of communication therefor

• US 6,501,955 B1
• Filed: 06/19/2000
• Issued: 12/31/2002
• Est. Priority Date: 06/19/2000
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Durrant, Randolph L., Scott, Logan, Reece, John K.
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): Perez-Gutierrez, Rafael
• Application Number:
  US09/596,653
• Time in Patent Office: 925 Days
• Field of Search: 455/456, 455/7, 455/11.1, 455/404, 455/521, 455/9, 455/10, 342/453, 342/457, 375/134, 375/137
• US Class Current: 455/456.1
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01S 5/0273 using multipath or indirect path propagation signals in position determination
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04B 7/155 Ground-based stations H04B7/204 takes precedence
• CPC Class Codes: H04B 7/2606 Arrangements for base station coverage control, e.g. by using relays in tunnels
• CPC Class Codes: H04W 16/26 Cell enhancers or enhancement, e.g. for tunnels, building shadow

Abstract

A RF signal repeater system is added to a wireless communications network which increases user data rates at the periphery of the cellular coverage area by boosting the downlink (base station to mobile user) signal and uplink (mobile user to base station) signal. The RF signal repeater system includes a signal tagging means that adds a unique electronic signature to the repeated signal such that position determination errors due to a non-line of sight propagation path can be corrected. The repeated signal is received and processed with a location measurement unit to determine the time of arrival and to extract the signal tag of the repeated signal. The time of arrival measurement and recovered signal tag are then processed at a mobile location center to determine the true position of the transmitter.

Claims

1. A mobile unit position determination system, comprising:

a) a signal repeater comprising;

a first antenna for communicating with a base station;

a second antenna for communicating with a mobile unit;

a first signal path for coupling signals received on the second antenna to the first antenna;

a second signal path for coupling signals received on the first antenna to the second antenna;

a first modulator inserted in the first signal path for tagging the signals coupled to the first antenna with an electronic signature identifying the signal repeater;

a mixer inserted in the first signal path for frequency translating the signals coupled to the first antenna; and

a mixer inserted in the second signal path for frequency translating the signals coupled to the second antenna;

b) a mobile unit;

c) a base station;

the base station including a location measurement unit for determining a time of arrival of signals arriving at the base station, the location measurement unit including a demodulator for extracting the electronic signature transmitted by the signal repeater; and

d) a mobile location center for processing the time of arrival measurement and the electronic signature into a position estimate of the mobile unit, the mobile location center including a database for storing the location of the signal repeater.

2. A signal repeater, comprising:

a first antenna for communicating with a base station;

a second antenna for communicating with a mobile unit;

a first signal path for coupling signals received on the second antenna to the first antenna;

a second signal path for coupling signals received on the first antenna to the second antenna;

a first modulator inserted in the first signal path for tagging the signals coupled to the first antenna with an electronic signature identifying the signal repeater;

a mixer inserted in the first signal path for frequency translating the signals coupled to the first antenna; and

a mixer inserted in the second signal path for frequency translating the signals coupled to the second antenna.

3. The signal repeater of claim 2, further comprising a second modulator inserted in the second signal path for tagging the signals coupled to the second antenna with an electronic signature identifying the signal repeater.

4. The signal repeater of claim 3, wherein the second modulator is a frequency modulator for tagging the signals coupled to the second antenna with frequency shift keying.

5. The signal repeater of claim 2, wherein the first modulator is a frequency modulator for tagging the signals coupled to the first antenna with frequency shift keying.

6. The signal repeater of claim 5, further comprising:

a mobile equivalent unit for demodulating transmissions from the base station to determine transitions between data frames in the demodulated transmissions, the mobile equivalent unit coupled to the frequency modulator to synchronize shifts in the frequency shift keying to the transitions between data frames.

7. The signal repeater of claim 6, wherein the mobile equivalent is a GSM mobile equivalent.

8. A method of communication, comprising:

providing a base station, a mobile unit, and a signal repeater all located in a cell of a wireless network;

receiving at the signal repeater a signal from either the base station or the mobile unit;

tagging the received signal with an electronic signature identifying the signal repeater, the electronic signature being generated at the signal repeater by frequency modulating the received signal; and

transmitting the tagged signal from the signal repeater.

9. The method of claim 8, wherein the frequency modulating comprises frequency shift keying the received signal, the frequency shift keying being synchronized to shift between data frames in the received signal.

10. The method of claim 9, further comprising frequency translating the tagged signal, wherein the transmitting the tagged signal comprises transmitting a frequency-translated tagged signal.

11. The method of claim 10, wherein the wireless network comprises a GSM network, the receiving at the signal repeater comprises receiving a downlink signal from the base station, the downlink signal having a frequency hopping pattern, and the transmitting the tagged signal comprises transmitting a frequency-translated tagged downlink signal having a transformed frequency hopping pattern to the mobile unit.

12. The method of claim 11, wherein the transformed hopping pattern of the repeated downlink signal is transformed from hopping pattern of the downlink signal according to an extended Mobile Allocation message.

13. The method of claim 10, wherein the received signal is on a first frequency band and the frequency-translated tagged signal is on a second frequency band.

14. A method of communication, comprising:

providing a base station, a mobile unit, and a signal repeater all located in a cell of a wireless network;

receiving at the signal repeater a signal from either the base station or the mobile unit;

tagging the received signal with an electronic signature identifying the signal repeater, the electronic signature being generated at the signal repeater by phase modulating the received signal; and

transmitting the tagged signal from the signal repeater.