Method and apparatus for performing random access in a mobile communication system

• US 10,356,821 B2
• Filed: 10/08/2015
• Issued: 07/16/2019
• Est. Priority Date: 01/29/2014
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Woo-Seong, Kim, Soeng-Hun, Van Der Velde, Himke
• Primary Examiner(s): Lee, Jae Y
• Assistant Examiner(s): Guadalupe Cruz, Aixa A
• Application Number:
  US14/879,020
• Publication Number:
  US 20160037562A1
• Time in Patent Office: 1,377 Days
• CPC Class Codes: H04L 5/00 Arrangements affording multiple use of the transmission path
• CPC Class Codes: H04W 36/0005 Control or signalling for completing the hand-off
• CPC Class Codes: H04W 36/0077 of access information of target access point
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 74/006 in the downlink, i.e. towards the terminal
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B

Abstract

The present disclosure relates to a method and apparatus for performing random access in a user equipment for a small cell e-NB with a small cell service area in heterogeneous e-NB cell carrier integration (dual connectivity or inter-eNB carrier aggregation) in mobile communication systems. In accordance with an aspect of the present disclosure, a method for performing random access in a mobile communication system is provided. The method includes receiving a configuration request message for configuring a Serving Cell Group (SCG) from a second eNB located in a service area of a first eNB through the first eNB; configuring an SCG cell based on the configuration request message, and sending a configuration response message in response to the configuration request message to the second eNB through the first eNB; and performing random access if there is uplink data present on a logic channel (LCH) relocated into the SCG cell.

Claims

1. A method by a terminal communicating with a master base station and a secondary base station, the method comprising:

receiving, from a master base station, a message to change a primary secondary cell (PSCell) of a secondary cell group (SCG) associated with a secondary base station, the message including configuration information related to the SCG;

changing the PSCell to a new PSCell based on the message;

identifying whether the configuration information related to the SCG includes mobility control information related to the SCG;

starting a timer with a timer value included in the mobility control information related to the SCG based on the configuration information including the mobility control information related to the SCG;

starting to synchronize to a downlink of the new PSCell based on the configuration information including the mobility control information related to the SCG;

initiating a random access procedure on the new PSCell based on preamble information included in the mobility control information related to the SCG based on the configuration information including the mobility control information related to the SCG; and

transmitting, to the master base station, a response message in response to the message,

wherein the timer is stopped in response to the random access procedure being completed successfully.

2. The method of claim 1, wherein initiating the random access procedure comprises performing contention based random access based on no dedicated preamble or radio resource being reserved for the random access in the preamble information.

3. The method of claim 1, wherein initiating the random access procedure comprises performing non-contention based random access based on a dedicated preamble or a radio resource being reserved for the random access in the preamble information.

4. The method of claim 1, wherein the timer value is set by the secondary base station.

5. The method of claim 1, wherein performing the random access procedure comprises,

sending specific preamble or MAC control element corresponding to SCG C-RNTI to the secondary base station.

6. The method of claim 5, wherein sending specific preamble or MAC control element to the secondary base station is for confirming success of a change to the new PSCell.

7. A method by a master base station communicating with a terminal and a secondary base station, the method comprising:

transmitting, to a terminal, a message to change a primary secondary cell (PSCell) of a secondary cell group (SCG) associated with a secondary base station, the message including configuration information related to the SCG;

performing a random access procedure on a new PSCell based on preamble information; and

wherein a timer, which is started with a timer value included mobility control information related to the SCG being the configuration information including the mobility control information related to the SCG, is stopped in the terminal in response to the random access procedure being completed successfully, and

wherein the terminal initiates the random access procedure on the new PSCell based on the preamble information included in the mobility control information related to the SCG based on the configuration information including the mobility control information related to the SCG,

wherein the terminal starts to synchronize to a downlink of the new PSCell based on the configuration information including the mobility control information related to the SCG.

8. The method of claim 7, wherein performing the random access procedure comprises performing contention based random access in response to no dedicated preamble or radio resource being reserved for the random access in the preamble information.

9. The method of claim 7, wherein performing the random access procedure comprises performing non-contention based random access in response to a dedicated preamble or a radio resource being reserved for the random access in the preamble information.

10. A terminal communicating with a master base station and a secondary base station, the terminal comprising:

a transceiver; and

a processor coupled with the transceiver and configured to;

receive, from a master base station, a message to change a primary secondary cell (PSCell) of a secondary cell group (SCG) associated with a secondary base station, the message including configuration information related to the SCG;

change the PSCell to a new PSCell based on the message,

identify whether the configuration information related to the SCG includes mobility control information related to the SCG,

start a timer with a timer value included in the mobility control information related to the SCG based on the configuration information including the mobility control information related to the SCG,

start synchronizing to a downlink of the new PSCell based on the configuration information including the mobility control information related to the SCG,

initiate, via the transceiver, a random access procedure on the new PSCell based on preamble information included in the mobility control information related to the SCG based on the configuration information including the mobility control information related to the SCG, and

transmit, to the master base station, a response message in response to the message,

wherein the timer is stopped in response to the random access procedure being completed successfully.

11. The terminal of claim 10, wherein the processor is further configured to perform contention based random access in response to no dedicated preamble or radio resource being reserved for the random access in the preamble information.

12. The terminal of claim 10, wherein the processor is further configured to perform non-contention based random access in response to a dedicated preamble or a radio resource being reserved for the random access in the preamble information.

13. A master base station communicating with a terminal and a secondary base station, the master base station comprising:

a transceiver; and

a processor coupled with the transceiver and configured to;

transmit, to a terminal, a message to change a primary secondary cell (PSCell) of a secondary cell group associated with a secondary base station (SCG), the message including configuration information related to the SCG,

perform, a random access procedure on a new PSCell based on preamble information, and

receive, from a terminal, a response message in response to the message,

wherein a timer, which is started with a timer value included in mobility control information related to the SCG based on the configuration information including the mobility control information related to the SCG, is stopped in the terminal in response to the random access procedure being completed successfully, and

wherein the terminal initiates the random access procedure on the new PSCell based on the preamble information included in the mobility control information related to the SCG based on the configuration information including the mobility control information related to the SCG,

wherein the terminal starts to synchronize to a downlink of the PSCell based on the configuration information including the mobility control information related to the SCG.

14. The master base station of claim 13, wherein the processor is configured to perform contention based random access in response to no dedicated preamble or radio resource being reserved for the random access in the preamble information.

15. The master base station of claim 13, wherein the processor is configured to perform non-contention based random access in response to a dedicated preamble or a radio resource being reserved for the random access in the preamble information.