Handover technique for wireless communications enabled devices

• US 9,369,936 B2
• Filed: 03/19/2008
• Issued: 06/14/2016
• Est. Priority Date: 04/02/2007
• Status: Active Grant

• Current Assignee: British Telecommunications PLC (BT Group PLC)
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: Chin, Choong M, Low, Andy Ly, Chien, Su Fong
• Primary Examiner(s): Chang, Kent
• Assistant Examiner(s): AU, SCOTT D
• Application Number:
  US12/594,500
• Publication Number:
  US 20100130206A1
• Time in Patent Office: 3,009 Days
• Field of Search: 455436-445
• US Class Current: 1/1
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 36/36 by user or terminal equipment

Abstract

A method of triggering a network handover controlled by a communications device in a communications system comprising a plurality of networks with which the communications device can perform a handover operation to, the method comprising the steps of: determining a signal characteristic of each available candidate network in said communications system; forecasting a future value of said signal characteristic; determining a future handover margin for said signal characteristic of the network connection established by said communications device; determining if another available candidate network signal characteristic exceeds said handover margin at a future time, and if so, performing a handover operation to said other available candidate network, wherein said future handover margin for said signal characteristic is varied dynamically in dependence on said forecasted signal characteristic.

Claims

1. A method of triggering a network handover in a communications system comprising a mobile communications device and a plurality of network access points, wherein a plurality of said network access points provide at least one signal to said mobile communications device, the method comprising:

determining one or more signal characteristics of each communications channel available to the mobile communications device to establish communications with a network access in said communications system;

forecasting a future value of each said signal characteristic;

forecasting a future handover margin for each said signal characteristic; and

determining if, at a predetermined future point in time, another communications channel is available to another network access point for the mobile communications device to handover to from the current communications channel established with the current network access point by determining if the future value of a signal characteristic of said other communications channel is predicted at that time to exceed the value of the equivalent signal characteristic of the current communications channel at that time by at least the value of the handover margin predicted at that time,

wherein the future handover margin is dynamically dependent on the predicted probability of a trigger error occurring.

2. A method as claimed in claim 1, wherein the method further comprises:

the mobile communications device controlling the handover operation to said other network access point via said other communications channel.

3. A method as claimed in claim 1, wherein the forecasted value of said handover margin for each said signal characteristic is varied dynamically in dependence on the forecasted value of the respective signal characteristic.

4. A method as claimed in claim 1, wherein at least one said signal characteristic is determined at a network access point.

5. A method as claimed in claim 1, wherein at least one said signal characteristic is determined at the mobile communications device.

6. A method as claimed in claim 1, wherein at least one said signal characteristic comprises a received signal strength index (RSSI) of a signal between a network access point and the mobile communications device.

7. A method of triggering a network handover controlled by a communications device in a communications system comprising a plurality of networks with which the communications device can perform a handover operation to, the method comprising the steps of:

determining a signal characteristic of each available candidate network in said communications system;

forecasting a future value of said signal characteristic;

determining a future handover margin for said signal characteristic of the network connection established by said communications device;

determining if another available candidate network signal characteristic exceeds said handover margin at a future time, and if so, performing a handover operation to said other available candidate network, wherein said future handover margin for said signal characteristic is dynamically varied in response to said forecast signal characteristic, and

wherein the future handover margin is dynamically dependent on the predicted probability of a trigger error occurring.

8. A method as claimed in claim 7, wherein the margin varies with the location of the communications device.

9. A method as claimed in claim 8, wherein the margin varies with the number of candidate networks.

10. A method as claimed in claim 8, wherein a trigger error comprises a false trigger error.

11. A method as claimed in claim 8, wherein the trigger error comprises a false non-trigger.

12. Apparatus arranged to perform a method of triggering a network handover in a communications system comprising a mobile communications device and a plurality of network access points, wherein a plurality of said network access points provide at least one signal to said mobile communications device, the apparatus comprising:

one or more signal processors arranged to determine one or more signal characteristics of each communications channel available to the mobile communications device to establish communications with a network access point in said communications system;

one or more forecasters arranged to forecast a future value of each said signal characteristic;

one or more forecasters arranged to a future handover margin for each said signal characteristic; and

one or more processors arranged to determine if, at a predetermined future point in time, another communications channel is available to another network access point for the mobile communications device to handover to from the current communications channel established with the current network access point by;

determining if the future value of a signal characteristic of said other communications channel is predicted at that time to exceed the value of the equivalent signal characteristic of the current communications channel at that time by at least the value of the handover margin predicted at that time,

wherein the future handover margin is dynamically dependent on the predicted probability of a trigger error occurring.

13. A communications system arranged to implement a method of triggering a network handover controlled by a communications device in said communications system, the system comprising:

a plurality of candidate networks with which the communications device can perform a handover operation to;

one or more signal processors to determine one or more signal characteristics of each signal detected for an available candidate network in said communications system;

one or more data stores arranged to store data on said signal characteristics as time-series data;

one or more processor components arranged to;

forecast a future value of one or more of said detected signal characteristics from time-series data;

determine a future handover margin for said signal characteristic of the network connection established by said communications device;

determine if another available candidate network signal characteristic exceeds said handover margin at a future time, and if so,

control the performance of a handover operation to said other available candidate network, wherein said future handover margin for said signal characteristic is dynamically varied in response to said forecasted signal characteristic, and

wherein the future handover margin is dynamically dependent on the predicted probability of a trigger error occurring.

14. A communications system as claimed in claim 13, wherein the trigger error comprises a false trigger.

15. A communications system as claimed in claim 13, wherein the trigger error comprises a false non-trigger.