Two-way paging system and apparatus

• US 5,708,971 A
• Filed: 03/13/1995
• Issued: 01/13/1998
• Est. Priority Date: 01/11/1994
• Status: Expired due to Fees

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Dent, Paul W.
• Primary Examiner(s): VO, NGUYEN THANH
• Application Number:
  US08/402,947
• Time in Patent Office: 1,037 Days
• Field of Search: 455/33.1, 455/38.1, 455/38.3, 455/54.1, 455/54.2, 455/255, 455/343, 455/264, 455/38.2, 340/825.44, 340/311.1, 379/57, 379/58, 379/59
• US Class Current: 340/7.22
• CPC Class Codes: G08B 3/1008 Personal calling arrangements or devices, i.e. paging systems selective calling systems and call receivers H04W84/00, H04W68/00
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 21/08 the units being spaced along or adjacent to a rectilinear path waveguide fed H01Q21/0037
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H04B 7/04 using two or more spaced independent antennas
• CPC Class Codes: H04B 7/0837 using pre-detection combining H04B7/0868 takes precedence
• CPC Class Codes: H04B 7/0851 using training sequences or error signal minimizing error signal H04B7/0854
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• CPC Class Codes: H04B 7/18515 Transmission equipment in satellites or space-based relays
• CPC Class Codes: H04B 7/18532 Arrangements for managing transmission, i.e. for transporting data or a signalling message
• CPC Class Codes: H04B 7/18567 Arrangements for providing additional services to the basic mobile satellite telephony service
• CPC Class Codes: H04L 1/0069 Puncturing patterns
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 2001/0098 Unequal error protection
• CPC Class Codes: H04L 25/03331 Arrangements for the joint estimation of multiple sequences
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 84/025 with acknowledge back capability
• CPC Class Codes: H04W 88/022 Selective call receivers
• CPC Class Codes: H04W 88/185 : Selective call encoders for paging networks, e.g. paging centre devices

Abstract

Paging systems typically include a network of ground stations or orbiting satellites equipped with transmitters and antennas for transmitting paging messages to small, battery-operated paging receivers that are worn about the person, known as pagers. Conventional pagers are receive-only devices and the network receives no confirmation that paging has been successful. The present invention includes the provision of two-way pagers that contain a transmitter for transmitting an acknowledgment confirming reception of a paging message, and a network of receiving stations able to receive said acknowledgments. The network makes use of advanced phased-array antenna signal processing techniques to render the return link operable with much less transmitter power in the portable unit than employed by the base station.

Claims

1. A wireless paging unit for receiving alert messages addressed thereto transmitted by a paging network and for transmitting an acknowledgment in response to receipt thereof, comprising:

antenna means for receiving and transmitting signals;

antenna coupling means coupled to said antenna means and controlled by a control means to adapt said antenna means for one of reception and transmission;

a receiver connected via said antenna coupling means to said antenna means for receiving a signal and generating a time-of-arrival indication upon detecting a predetermined signal pattern;

said control means also for receiving said time of arrival indication and in response thereto for adapting said antenna means for transmission and for activating a transmitter at a time based on said indicated time-of-arrival; and

wherein said transmitter is coupled via said antenna coupling means to said antenna means and activated by said control means to transmit a digitally coded acknowledgment signal at said time.

2. A paging unit according to claim 1 in which said control means further comprises:

high-frequency crystal reference oscillator and counter means for determining an operating frequency of said receiver and said transmitter; and

low-frequency oscillator and counter means for determining a power-down period for said receiver and said high frequency crystal reference oscillator.

3. A paging unit according to claim 2 in which said high-frequency crystal reference oscillator and counter means is controlled during power-on periods to calibrate said low frequency oscillator and counter means.

4. A paging unit according to claim 2 in which said operating frequency determination is performed using a frequency synthesizer programmed by said control means to adaptively generate either a transmit or a receive frequency.

5. A paging unit according to claim 4 in which said transmit frequency is the same as said receive operating frequency and said receive frequency is a receive local oscillator frequency.

6. A paging unit according to claim 5 in which said receive local oscillator frequency is the same as said receive operating channel frequency.

7. A paging unit according to claim 1 in which said receiver is a homodyne receiver.

8. The wireless paging unit of claim 1, wherein said control means determines said time for activating said transmitter using said indicated time-of-arrival and a predetermined delay.

9. The wireless paging unit of claim 8, wherein said predetermined delay is 2-10 milliseconds.

10. The wireless paging unit of claim 1, wherein said control means includes a counter which is continuously incrementing to generate count values and said control means adds said indicated time of arrival, a starting state of said counter and a predetermined delay to identify a particular count value as said time for activating said transmitter.

11. The wireless paging unit of claim 10, wherein said predetermined delay is 2-10 milliseconds.

12. A wireless paging unit capable of receiving alert messages transmitted thereto from a paging network and capable of transmitting an acknowledgment of receipt thereof, comprising:

antenna means for receiving and transmitting signals;

a receiver connected to said antenna means for receiving a signal and converting said signal to numerical samples when indicated by a timing control means;

memory means for storing said numerical samples in time order of reception;

processing means for processing said stored numerical samples to determine a location in said memory means of a predetermined signal pattern and to generate a time-of-arrival indication based on said location; and

timing control means for receiving said time-of-arrival indication and for activating a transmitter to transmit a digitally coded reply with a predetermined timing related to said indicated time-of-arrival.

13. A paging unit according to claim 12 in which said timing control means, prior to activating said transmitter, adapts said antenna means from a receive state to a transmit state.

14. A paging unit according to claim 12 in which said processing means further processes said stored numerical samples to produce a frequency error indication.

15. The paging unit according to claim 14 in which said timing control means uses said frequency error indication in activating said transmitter at a desired frequency.

16. The paging unit according to claim 15 in which said frequency error indication is used by said timing control means to adjust a frequency synthesizer to generate transmit frequency which has been compensated for said frequency error.

17. The paging unit according to claim 14 in which said frequency error indication is used to correct a frequency of a crystal reference oscillator.

18. The paging unit according to claim 17 in which said crystal reference oscillator is used to control the operating channel frequency of said transmitter.

19. A wireless paging unit capable of receiving alert messages transmitted from a paging network and of transmitting a reply in response to receipt thereof, comprising:

a first oscillator means for determining a receiver power down period based on a calibration count value;

a second oscillator means for determining operating channel frequencies of said receiver and of a transmitter;

said receiver being activated by a signal controlled by said first oscillator means to receive and process a signal received on a receive operating channel frequency and to produce a time-of-arrival and frequency error indication from said received signal;

frequency correction means for using said frequency error indication to correct said second oscillator means and to use said corrected second oscillator means to perform a calibration measurement to determine said calibration count value; and

timing control means for receiving said time of arrival indication and in response thereto for activating a transmitter to transmit a digitally coded reply having a predetermined timing related to said indicated time-of-arrival and at an operating channel frequency derived from said second oscillator means and compensated for said frequency error.