Radio communication arrangements

• US 20020176445A1
• Filed: 04/30/2002
• Published: 11/28/2002
• Est. Priority Date: 05/01/2001
• Status: Active Grant

• Current Assignee: Uniloc 2017 LLC (SoftBank Group Corp.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Melpignano, Diego
• Granted Patent: US 7,193,989 B2
• Time in Patent Office: Days
• US Class Current: 370/480
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 68/00 User notification, e.g. alerting and paging, for incoming communication, change of service or the like

Abstract

A communications arrangement 10 is disclosed which comprises first and second communications devices MT, AP, said first device MT being adapted to enter into a page scan state in which it is receptive to transmissions on a particular page scan frequency f_ps and said second device AP being adapted to transmit a page train A which is centered around an estimate of said page scan frequency f_ps. The arrangement is characterized in that in that, under predetermined circumstances following prior communication between said devices MT, AP, said second device AP is adapted to transmit a page train A′ which has been modified to start on a frequency f(k) shifted to correspond to said estimate and preferably also truncated to avoid transmission of at least one predetermined frequency sub-train A₂ of the original page train A.

Claims

1. A communications arrangement comprising first and second communications devices, said first device being adapted to enter into a page scan state in which it is receptive to transmissions on a particular page scan frequency and said second device being adapted to transmit a page train which is centered around an estimate of said page scan frequency, characterized in that, under predetermined circumstances following prior communication between said devices, said second device is adapted to transmit a page train which has been modified to start on a frequency shifted to correspond to said estimate.

2. An arrangement according to claim 1, wherein said predetermined circumstances include a consideration of a time lapse between said prior communication and the transmission of said modified page train.

3. An arrangement according to claim 1 or claim 2, wherein said prior communication comprises a response to an inquiry procedure executed between said devices.

4. An arrangement according to any preceding claim, wherein said prior communication was terminated by a communications link failure.

5. An arrangement according to any preceding claim, wherein said modified page train is truncated, by for example said second device setting a page time-out which ensures that a second frequency sub-train of said page train is not transmitted and said page-time out preferably being set before said modified page train is transmitted.

6. An arrangement according to any preceding claim, wherein said page scan frequency is shifted on the basis of at least one of clock offset information and a network address relating to said first device.

7. An arrangement according to any preceding claim, wherein said first device comprises a master unit in a set of master units, and said second device comprises a slave unit, said modified page train comprising part of a series of page trains used by said slave unit to page a plurality of master units in said set and said series of page trains preferably comprising page trains respectively modified such that each starts on an estimate of the page scan frequency of one of said plurality of master units being paged and preferably being truncated such that a respective frequency sub-train thereof is not transmitted.

8. A arrangement according to any one of claims 1 to 6, wherein said first device comprises a slave unit amongst a plurality of slave units and said second device comprises a master unit, said modified page train comprising part of a series of page trains used by said master unit to page a plurality of said slave units sequentially, each said page train in said series being modified such that it starts on an estimate of the respective page scan frequency of a slave unit in said series and each said modified page train preferably being truncated such that a respective frequency sub-train thereof is not transmitted.

9. A arrangement according to claim 8, wherein said sequential paging is used by said master unit to respond to multiple requests from slave units for handoffs.

10. A arrangement according to any one of claims 1 to 6, wherein the or each said modified page train is used to attempt reconnection of a communications link previously in place between said devices, the or each said first device preferably being adapted to enter into a continuous said page scan state on detection of a breakdown in said previously existing communications link and preferably to remain in said page scan state for at least a predetermined period to wait for a said page train.

11. A arrangement according to claim 10, wherein said second device attempts to re-establish said previously existing connection by repeating said modified page train a plurality of times.

12. A arrangement according to any preceding claim, wherein the or each said second device stops paging the or each said first device at the end of a page time-out event, said time-out preferable being settable by or in the or each said second device.

13. An arrangement according to any preceding claim, including determining, from reception or not of responses to said modified page train from the or each said first device, whether or not the or each said first device is within communications range of said second device.

14. A communications device suitable for use in an arrangement according to any preceding claim, wherein said communications device is adapted to page at least one further communications device using a page train centered around a page scan frequency of said further communications device, wherein, under predetermined circumstances following prior communication between said devices, said communications device is adapted to transmit a page train which has been modified to start on a frequency shifted to correspond to said estimate.

15. A device according to claim 14, wherein said predetermined circumstances include a consideration of a time lapse between said prior communication and the transmission of said modified page train.

16. A device according to claim 14 or claim 15, wherein said prior communication comprises a response to an inquiry procedure executed between said device and a said further device.

17. A device according to any one of claims 14 to 16, wherein said prior communication was terminated by a communications link failure.

18. A device according to any one of claims 14 to 17, wherein said modified page train is truncated, preferably by said device setting a page time-out which ensures that a second frequency sub-train of said page train is not transmitted, said page-time out preferably being set before said modified page train is transmitted.

19. A device according to any one of claims 14 to 18, wherein said page scan frequency is estimated from at least one of clock offset information and a network address relating to said further device.

20. A device according to any one of claims 14 to 19 comprising an access point or a mobile terminal, preferably of a Bluetooth arrangement.

21. A method of operating a communications arrangement comprising first and second communications devices, said first device being adapted to enter into a page scan state in which it is receptive to transmissions on a particular page scan frequency and said second device being adapted to transmit a page train centered around an estimate of said page scan frequency of said first device, the method including said second device transmitting, under predetermined circumstances following prior communication between said devices, a page train which has been modified to start on a frequency shifted to correspond to said estimate.

22. A method according to claim 21, including truncating said modified page train, preferably by setting a page time-out which ensures that a frequency sub-train of said page train is not transmitted.

23. A method according to claim 21 or claim 22, including estimating said page scan frequency on the basis of at least one of a clock offset and an address of said first device.

24. A method according to any one of claims 21 to 23, used for handing off said first device from said second device to a further device.

25. A method according to any one of claims 21 to 24, used for re-establishing a lost connection between said devices.

26. A method according to any one claims 21 to 25, used by said second device to establish connections with multiple said first devices.

27. A method according to any one of claims 21 to 26, said communications arrangement comprising a Bluetooth arrangement and the or each said first and second devices respectively comprising access points and mobile terminals or mobile terminals and access points thereof.