Method and system for repeating pages

• US 5,963,846 A
• Filed: 03/31/1997
• Issued: 10/05/1999
• Est. Priority Date: 03/31/1997
• Status: Expired due to Fees

• Current Assignee: Torsal Technology Group Limited LLC (Intellectual Ventures LLC)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Kurby, Christopher Neil
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): NGUYEN, DUC M
• Application Number:
  US08/829,298
• Time in Patent Office: 918 Days
• Field of Search: 455/11.1, 455/12.1, 455/13.1, 455/13.2, 455/428, 455/458, 455/20, 455/31.1, 455/38.1
• US Class Current: 455/12.1
• CPC Class Codes: H04B 7/18567 Arrangements for providing additional services to the basic mobile satellite telephony service

Abstract

A paging repeater (22) receives (152) a paging signal (30) transmitted (138) by a low-earth orbit satellite (24) while compensating (150) for Doppler effects, modifying (156) the paging signal (30) to produce a repeat signal (40), and transmitting (166) the repeat signal shifted in both the time and frequency domains so as to preclude the generation of interference. A pager (28) receives a paging signal (30) directly from the satellite (24) while compensating (108) for Doppler effects whenever the pager (28) is unshadowed with regard to the satellite (24), or receiving a repeat signal (40) from a paging repeater (22) whenever the pager (28) is shadowed with regard to the satellite (24).

Claims

1. A method for repeating a paging message transmitted by a moving paging system base station wherein said paging message is conveyed by a first signal, said first signal being transmitted over a first frequency channel having a predetermined bandwidth, said method comprising the steps of:

increasing, by said pager, said reception bandwidth to an amount sufficiently greater than said predetermined bandwidth to contain said first frequency channel when said first frequency channel is shifted in frequency due to a Doppler effect;

reducing, by said pager, said reception bandwidth to an amount substantially equal to said predetermined bandwidth when signal strength of said first signal is insufficient for said pager to receive said first signal;

receiving, by a paging repeater, said first signal from said paging system base station, said paging repeater having a reception bandwidth sufficiently greater than said predetermined bandwidth;

adjusting by said paging repeater, said first signal to compensate for said Doppler effect so as to produce a second signal containing said paging message; and

transmitting, by said paging repeater, said second signal containing said paging message over a second frequency channel having substantially said predetermined bandwidth.

2. A method as claimed in claim 1 additionally comprising the step of placing said moving paging system base station in an orbit around the earth.

3. A method as claimed in claim 1 wherein said receiving step additionally comprises the step of establishing said reception bandwidth to contain said first frequency channel, a first guard channel, and a second guard channel.

4. A method as claimed in claim 1 wherein:

up to a maximum downward Doppler shift of said first frequency channel results from a relative divergence of said paging system base station and said paging repeater;

up to a maximum upward Doppler shift of said first frequency channel result from a relative divergence of said paging system base station and said paging repeater;

said receiving step additionally comprises the step of establishing said reception bandwidth to contain said first frequency channel, plus a first guard channel, plus a second guard channel;

said first guard channel is allocated a bandwidth sufficient, when summed with said predetermined bandwidth, to contain said first frequency channel when said first frequency channel experiences said maximum downward Doppler shift; and

said second guard channel is allocated a bandwidth sufficient, when summed with said predetermined bandwidth, to contain said first frequency channel when said first frequency channel experiences said maximum upward Doppler shift.

5. A method as claimed in claim 1 wherein said adjusting step comprises the steps of:

demodulating said first signal to obtain said paging message; and

modulating said paging message to obtain said second signal.

6. A method as claimed in claim 5 additionally comprising the step of altering said paging message after said demodulation step and prior to said modulation step.

7. A method as claimed in claim 6 wherein said altering step comprises the step of modifying a paging header within said paging message.

8. A method as claimed in claim 5 additionally comprising, after said demodulation step and prior to said modulation step, the steps of:

ascertaining from said paging message if said first signal includes an alternate paging channel;

assigning, if said first signal includes said alternate paging channel, data contained in said alternate paging channel to an alternate repeater channel; and

altering, if said first signal includes said alternate paging channel, said paging message to indicate the presence of said alternate repeater channel.

9. A method as claimed in claim 1 additionally comprising the step of locating said paging repeater proximate to a building having an interior volume such that a receiving antenna for said paging repeater is in a position to receive said first signal from said paging system base station and a transmitting antenna for said paging repeater is located within said building interior volume.

10. A communication system in which a paging message transmitted by a moving paging system base station is repeated, said paging message being conveyed by a first signal transmitted over a first frequency channel having a predetermined bandwidth, said system comprising:

a paging repeater receiver configured to receive said first signal from said paging system base station, said paging repeater receiver being configured to have a reception bandwidth sufficiently greater than said predetermined bandwidth to contain said first frequency channel when said first frequency channel is shifted in frequency due to a Doppler effect;

a paging repeater controller coupled to said receiver, said paging repeater controller being configured to adjust said first signal to compensate for said Doppler effect so as to produce a second signal containing said paging message;

a paging repeater transmitter coupled to said controller, said paging repeater transmitter being configured to transmit said second signal containing said paging message over a second frequency channel having substantially said predetermined bandwidth; and

at least one pager receiver in occasional contact with said paging repeater transmitter, said at least one pager receiver increasing a reception bandwidth to an amount sufficiently greater than said predetermined bandwidth to contain said first frequency channel when said first frequency channel is shifted in frequency due to a Doppler effect;

reducing, by said pager receiver, said reception bandwidth when said first signal is not of sufficient strength for said pager receiver to receive said first signal.

11. A communication system as claimed in claim 10 additionally comprising a satellite in which said moving base station resides, said satellite being in an orbit around the earth.

12. A communication system as claimed in claim 10 wherein:

said paging repeater receiver, controller, and transmitter are located proximate to a building having an interior volume;

said communication system additionally comprises a receiving antenna coupled to said paging repeater receiver, said receiving antenna being positioned to receive said first signal from said paging system base station; and

said communication system additionally comprises a transmitting antenna coupled to said paging repeater transmitter, said transmitting antenna being located within said building interior volume.

13. A communication system as claimed in claim 10 wherein said paging repeater receiver is configured to establish said reception bandwidth to contain said first frequency channel, a first guard channel, and a second guard channel.

14. A communication system as claimed in claim 10 wherein said controller is configured to demodulate said first signal to obtain said paging message and to modulate said paging message to obtain said second signal.

15. A communication system as claimed in claim 14 wherein said controller is further configured to alter said paging message.

16. A communication system as claimed in claim 10 wherein:

up to a maximum downward Doppler shift of said first frequency channel results from a relative divergence of said paging system base station and said paging repeater;

up to a maximum upward Doppler shift of said first frequency channel result from a relative divergence of said paging system base station and said paging repeater;

paging repeater receiver is configured to establish said reception bandwidth to contain said first frequency channel, plus a first guard channel, plus a second guard channel;

said first guard channel is allocated a bandwidth sufficient, when summed with said predetermined bandwidth, to contain said first frequency channel when said first frequency channel experiences said maximum downward Doppler shift; and

said second guard channel is allocated a bandwidth sufficient, when summed with said predetermined bandwidth, to contain said first frequency channel when said first frequency channel experiences said maximum upward Doppler shift.

17. A method for paging wherein a pager receives a paging message from one of a moving paging system base station and a substantially stationary paging repeater, said method comprising the steps of:

(a) transmitting, at said paging system base station, a first signal containing said paging message over a first frequency channel having a predetermined bandwidth;

(b) receiving, at said paging repeater, said first signal from said paging system base station, said paging repeater having a reception bandwidth sufficiently greater than said predetermined bandwidth to contain said first frequency channel when said first frequency channel is shifted in frequency due to a Doppler effect;

(c) adjusting, at said paging repeater, said first signal to compensate for said Doppler effect so as to produce a second signal containing said paging message;

(d) transmitting, at said paging repeater, said second signal over a second frequency channel having substantially said predetermined bandwidth;

(e) waking up said pager from a standby mode;

(f) adjusting, at said pager after said step (e), a pager reception bandwidth such that said pager reception bandwidth is sufficiently greater than said predetermined bandwidth to contain said first frequency channel when said first frequency channel is shifted in frequency due to said Doppler effect;

(g) receiving, at said pager after said step (f), said first signal from said paging system base station when said first signal is of sufficient strength and clarity for reception at said pager;

(h) reducing, at said pager after said step (g), said pager reception bandwidth, when said first signal from said paging system base station is of insufficient strength or clarity for reception, from said pager reception bandwidth of said step (f);

(i) receiving, at said pager after said step (h), said second signal from said paging repeater when said second signal is of sufficient strength and clarity for reception at said pager; and

(j) returning, after said step (i), said pager to said standby mode.

18. A method as claimed in claim 17 additionally comprising the steps of:

determining, at said pager, when said step (g) receives said first signal, if said pager can synchronize with said first signal;

determining, at said pager, when said pager can synchronize with said first signal, if said first signal contains said paging message;

discerning, at said pager, when said first signal contains said paging message, if said paging message is addressed to said pager; and

processing, at said pager, said paging message when said paging message is addressed to said pager.

19. A method as claimed in claim 17 additionally comprising, when said second signal in step (i) is of sufficient strength and clarity for reception, the steps of:

determining, at said pager, when said step (i) receives said second signal, if said pager can synchronize with said second signal;

determining, at said pager, when said pager can synchronize with said second signal, if said second signal contains said paging message;

discerning, at said pager, when said second signal contains said paging message, if said paging message is addressed to said pager; and

processing, said paging message when said paging message is addressed to said pager.

20. A method as claimed in claim 17 additionally comprising the step of placing said paging system base station in a low-earth orbit around the earth.