METHOD AND APPARATUS FOR HANDOVER, AND METHOD OF DETERMINING DELAY PARAMETER IN WIRELESS COMMUNICATION SYSTEM

• US 20120276946A1
• Filed: 04/30/2012
• Published: 11/01/2012
• Est. Priority Date: 04/29/2011
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Lee, Sook Jin, Yoon, Hyunsoo, SUNG, Nak Woon, Shin, Seungjae
• Granted Patent: US 8,886,251 B2
• Time in Patent Office: Days
• US Class Current: 455/525
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 36/04 Reselecting a cell layer in multi-layered cells
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/32 by location or mobility data, e.g. speed data

Abstract

When a handover apparatus of a user terminal enters a small scale cell within a macrocell area in a state that it is connected to a macrocell, the handover apparatus acquires a delay parameter of the small scale cell and delays handover for a time period of the delay parameter of the small scale cell and determines handover to the small scale cell. Thereby, handover to the small scale cell for a temporal user of the small scale cell can be reduced.

Claims

1. A method in which a user terminal that is connected to a macrocell performs handover to a small scale cell within a macrocell area, the method comprising:

determining whether a handover criterion is satisfied for a time period of a delay parameter of the small scale cell when the user terminal enters the small scale cell; and

determining handover to the small scale cell when the handover criterion is continuously satisfied for the time period of the delay parameter.

2. The method of claim 1, further comprising receiving the delay parameter from a network management entity.

3. The method of claim 2, wherein the receiving the delay parameter comprises receiving the delay parameter from the network management entity through a control channel or a control message.

4. The method of claim 1, wherein the determining of whether a handover criterion is satisfied comprises:

receiving a signal from a base station of the macrocell and a base station of the small scale cell for the time period of the delay parameter;

determining whether the handover criterion is satisfied using the received signals for the time period of the delay parameter;

generating a timer variable and calculating a delay time whenever the handover criterion is satisfied; and

determining the handover when the delay time is larger than or equal to the time of the delay parameter.

5. The method of claim 4, wherein the calculating of a delay time comprises calculating the delay time by a difference between a generation time of the timer variable and a time at which the handover criterion is satisfied.

6. The method of claim 4, wherein the determining of whether a handover criterion is satisfied using the received signal comprises determining that the handover criterion is satisfied when intensity of a signal that is received from the base station of the macrocell is smaller than a signal threshold of the base station of the macrocell and when intensity of a signal that is received from the base station of the small scale cell is larger than a signal threshold of the base station of the macrocell.

7. The method of claim 1, wherein the delay parameter is acquired by applying numerical estimation to staying time measurement data of user terminals within an area of the small scale cell.

8. The method of claim 7, wherein the determining of whether a handover criterion is satisfied comprises:

generating a timer variable whenever the handover criterion is satisfied for a time period of the delay parameter;

removing the timer variable when the handover criterion is not satisfied again for the time period of the delay parameter; and

determining the handover and removing the timer variable when the handover criterion is satisfied for the time period of the delay parameter,

wherein the staying time measurement data are measured using a generation time and a removal time of the timer variable and a connection holding time with a base station of the small scale cell.

9. The method of claim 8, further comprising periodically reporting a generation time and a removal time of the timer variable and whether handover is performed to a base station of the small scale cell or a network management entity.

10. The method of claim 1, further comprising determining a temporary user and sustaining a connection to a base station of the macrocell when a handover criterion is not continuously satisfied for the time period of the delay parameter.

11. An apparatus for determining handover of a user terminal to a small scale cell within a macrocell area in a macrocell, the apparatus comprising:

a handover determining unit that acquires a delay parameter of the small scale cell and delays handover for the time period of the delay parameter of the small scale cell and then determines the handover when the user terminal enters the small scale cell; and

a handover performing unit that starts handover with the user terminal and the small scale cell when the handover is determined.

12. The apparatus of claim 11, wherein the handover determining unit determines handover to the small scale cell when a handover criterion is continuously satisfied for the time period of the delay parameter and sustains a connection to the macrocell when the handover criterion is not satisfied again for the time period of the delay parameter.

13. The apparatus of claim 12, wherein the handover determining unit determines whether the handover criterion is satisfied using intensity of signals that are received from a base station of the macrocell and a base station of the small scale cell.

14. The apparatus of claim 12, wherein the handover determining unit calculates a delay time by generating a timer variable whenever a handover criterion is satisfied for the time period of the delay parameter and determines handover to the small scale cell when the delay time is larger than or equal to the time of the delay parameter.

15. The apparatus of claim 14, wherein the handover determining unit removes the timer variable when the handover criterion is not satisfied again or when the handover is determined for the time period of the delay parameter.

16. The apparatus of claim 15, further comprising a reporting unit that periodically reports a generation time and a removal time of the timer variable to a network management entity,

wherein the network management entity calculates the delay parameter using the generation time and the removal time of the timer variable and a connection holding time of user terminals within an area of the small scale cell.

17. The apparatus of claim 16, wherein the handover determining unit receives the delay parameter from the network management entity through a control channel or a control message.

18. A method of determining a delay parameter in a network management entity that manages a small scale cell within a macrocell area, the method comprising:

calculating staying time measurement data of user terminals within a small scale cell area;

calculating a delay parameter by applying numerical estimation to the staying time measurement data; and

transmitting the delay parameter to a user terminal that enters the small scale cell in a state in which it is connected to the macrocell,

wherein handover to the small scale cell is delayed by the user terminal for a time period of the delay parameter.

19. The method of claim 18, wherein the calculating of staying time measurement data comprises:

receiving a connection holding time of user terminals in which the small scale cell has been connected to a base station from a base station of the small scale cell;

receiving a generation time of a timer variable that is generated whenever a handover criterion is satisfied for the time period of the delay parameter and a removal time of the removed timer variable when a handover criterion is not satisfied again for the time period of the delay parameter and when the handover is determined in the small scale cell from user terminals, having received the delay parameter; and

calculating the staying time measurement data using the connection holding time and a generation time and a removal time of the timer variable.

20. The method of claim 18, wherein the transmitting of the delay parameter comprises transmitting the delay parameter through a control channel or a control message.