User terminal and method for reselecting target cell

• US 10,251,112 B2
• Filed: 10/06/2017
• Issued: 04/02/2019
• Est. Priority Date: 04/10/2015
• Status: Active Grant

• Current Assignee: Kyocera Corporation
• Original Assignee: Kyocera Corporation
• Inventors: Fujishiro, Masato, Yamazaki, Chiharu, Chang, Henry
• Primary Examiner(s): Tran, Mong-Thuy T
• Application Number:
  US15/727,450
• Publication Number:
  US 20180035346A1
• Time in Patent Office: 543 Days
• Field of Search: 455436
• CPC Class Codes: H04J 11/0093 Neighbour cell search
• CPC Class Codes: H04W 16/32 Hierarchical cell structures
• CPC Class Codes: H04W 36/0061 of neighbour cell information
• CPC Class Codes: H04W 36/0085 Hand-off measurements
• CPC Class Codes: H04W 36/302 due to low signal strength
• CPC Class Codes: H04W 48/12 using downlink control channel
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A user terminal according to an embodiment includes a controller configured to select a target cell to be used as a serving cell from among a plurality of cells operated at different frequencies. The controller is configured to measure qualities of neighbor cells adjacent to a current serving cell at a predetermined timing even when a quality of the current serving cell satisfies predetermined quality criteria.

Claims

1. A user terminal for a mobile communication system, comprising:

a receiver configured to receive a first parameter broadcasted from a current serving cell and a second parameter broadcasted from the current serving cell; and

a controller configured to reselect a target cell to be used as a serving cell from among a plurality of cells operated at different frequencies, wherein

the first parameter is a parameter that defines a probability of performing reselection of the target cell,

the second parameter is a timer value to be set in a timer started at a timing at which a quality measurement for neighbor cells ends, and

the controller is configured to

in response to receiving the first parameter and the second parameter, periodically measure qualities of neighbor cells adjacent to the current serving cell at predetermined timings defined by the timer even when a quality of the current serving cell satisfies predetermined quality criteria,

compare a value corresponding to IMSI (International Mobile Subscriber Identity) of the user terminal with a value corresponding to the first parameter, and

reselect the target cell from among cells having a quality satisfying predetermined quality criteria, based on results of the quality measurement and the comparison.

2. The user terminal according to claim 1, wherein

the receiver is further configured to receive a reselection request signal that requests the reselection of the target cell, from the current serving cell,

the controller is further configured to measure the qualities of neighbor cells and to reselect the target cell, in response to receiving the reselection request signal, and

after reselecting the target cell, the controller is further configured to stop next reselection of the target cell until a predetermined period of time elapse from the reception of the reselection request signal.

3. The user terminal according to claim 2, wherein

the first parameter is included in a system information block different from the reselection request signal.

4. A method performed at a user terminal for a mobile communication system, comprising:

receiving a first parameter broadcasted from a current serving cell and a second parameter broadcasted from the current serving cell; and

reselecting a target cell to be used as a serving cell from among a plurality of cells operated at different frequencies, wherein

the first parameter is a parameter that defines a probability of performing reselection of the target cell,

the second parameter is a timer value to be set in a timer started at a timing at which a quality measurement for neighbor cells ends, and

the reselecting comprises;

in response to receiving the first parameter and the second parameter, periodically measuring qualities of neighbor cells adjacent to the current serving cell at predetermined timings defined by the timer even when a quality of the current serving cell satisfies predetermined quality criteria;

comparing a value corresponding to IMSI (International Mobile Subscriber Identity) of the user terminal with a value corresponding to the first parameter; and

reselecting the target cell from among cells having a quality satisfying predetermined quality criteria, based on results of the quality measurement and the comparison.