METHOD AND APPARATUS FOR PERFORMING RANDOM ACCESS IN A MOBILE COMMUNICATION SYSTEM

• US 20150223270A1
• Filed: 01/29/2015
• Published: 08/06/2015
• 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, Der Velde, Himke Van
• Granted Patent: US 10,448,427 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 for performing random access in a mobile communication system, the method comprising:

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.

2. The method of claim 1, wherein configuring an SCG cell comprises

activating the SCG cell based on information about initial SCG cell addition if the information is included in the configuration request message.

3. The method of claim 2, wherein performing random access comprises

determining whether there is uplink data present on the LCH relocated into the SCG cell;

and

triggering an SCG Buffer Status Report (BSR) and performing random access if there is uplink data present on the LCH relocated into the SCG cell.

4. The method of claim 2, wherein performing random access comprises

determining whether there is uplink data present on the LCH relocated into the SCG cell;

and

triggering an SCG Buffer Status Report (BSR) and performing contention based random access if no preamble or radio resource is reserved for random access, in case there is uplink data present on the LCH relocated into the SCG cell.

5. The method of claim 4, further comprising:

performing non-contention based random access if there is no uplink data present on the LCH relocated into the SCG cell and a preamble or a radio resource is reserved for random access.

6. The method of claim 1, wherein configuring an SCG cell comprises

activating the SCG cell based on information about SCG cell addition to an existing SCG if the information is included in the configuration request message.

7. The method of claim 6, wherein performing random access comprises

selecting a new LCH for offloading to the SCG cell from among LCHs, if there is configuration of a Logical Channel Group (LCG) for the existing SCG;

and

triggering an SCG Buffer Status Report (BSR) and performing random access if the new LCH takes higher priority over the existing LCH.

8. The method of claim 1, wherein performing random access comprises

changing the SCG cell into a master cell group if the configuration request message includes information about SCG cell change, and comparing uplink data on an LCH that corresponds to the changed SCG cell and a predetermined threshold;

and

triggering a Buffer Status Report (BSR) for the MCG and performing random access if the uplink data on the LCH is higher than the predetermined threshold.

9. A method for performing random access in a mobile communication system, the method comprising:

receiving a Serving Cell Goup (SCG) addition request message from a first eNB at a second eNB located in a service area of the first eNB;

sending a configuration request message to a UE through the first eNB in response to the SCG addition request message; and

receiving a configuration response message through the first eNB in return for the configuration request message, and performing random access with the UE.

10. The method of claim 9, wherein performing random access comprises

sending a random access request message to the UE on a downlink control channel;

and

monitoring a random access channel established on the downlink control channel, and sending a random access response message for allocation of a resource for a common control channel to the UE.

11. The method of claim 9, wherein performing random access comprises

receiving preamble information on an uplink random access channel;

establishing time sync for an uplink channel and sending the UE a random access response message for allocation of a resource for a common control channel, if the received preamble information is not a dedicated preamble; and

receiving information from the UE which includes C-RNTI, and allocating uplink/downlink radio resources for the UE if the C-RNTI is allocated to a small cell eNB (SeNB) for double connection.

12. The method of claim 9, wherein performing random access comprises

receiving preamble information on an uplink random access channel;

sending a random access response message to the UE if the received preamble information is a dedicated preamble; and

allocating uplink/downlink radio resources for the UE.

13. An apparatus for performing random access in a mobile communication system, the apparatus comprising:

a receiver for 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;

a controller for configuring an SCG cell based on the configuration request message, controlling a configuration response message in response to the configuration request message to be sent 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; and

a transmitter for sending the configuration response message under control of the controller.

14. The apparatus of claim 13, wherein the controller is configured to

activate the SCG cell based on information about initial SCG cell addition if the information is included in the configuration request message.

15. The apparatus of claim 14, wherein the controller is configured to

determine whether there is uplink data present on the LCH relocated into the SCG cell;

and

trigger an SCG Buffer Status Report (BSR) and perform random access if there is uplink data present on the LCH relocated into the SCG cell.

16. The apparatus of claim 14, wherein the controller is configured to

determine whether there is uplink data present on the LCH relocated into the SCG cell;

and

trigger an SCG Buffer Status Report (BSR) and perform contention based random access if no preamble or radio resource is reserved for random access, in case there is uplink data present on the LCH relocated into the SCG cell.

17. The apparatus of claim 16, wherein the controller is configured to

perform non-contention based random access if there is no uplink data present on the LCH relocated into the SCG cell and a preamble or a radio resource is reserved for random access.

18. The apparatus of claim 13, wherein the controller is configured to

activate the SCG cell based on information about SCG cell addition to an existing SCG if the information is included in the configuration request message.

19. The apparatus of claim 18, wherein the controller is configured to

select a new LCH for offloading to the SCG cell from among LCHs, if there is configuration of a Logical Channel Group (LCG) for the existing SCG;

and

trigger an SCG Buffer Status Report (BSR) and perform random access if the new LCH takes higher priority over the existing LCH.

20. The apparatus of claim 13, wherein the controller is configured to

change the SCG cell into a master cell group if the configuration request message includes information about SCG cell change, and compare uplink data on an LCH that corresponds to the changed SCG cell and a predetermined threshold;

and

trigger a Buffer Status Report (BSR) for the MCG and perform random access if the uplink data on the LCH is higher than the predetermined threshold.

21. An apparatus for performing random access in a mobile communication system, the apparatus comprising:

a receiver for receiving a Serving Cell Goup (SCG) addition request message from a first eNB at a second eNB located in a service area of the first eNB;

a transmitter for sending a configuration request message to a UE through the first eNB in response to the SCG addition request message; and

a controller for performing random access with the UE if a configuration response message through the first eNB is received by the receiver in return for the configuration request message.

22. The apparatus of claim 21, wherein the controller is configured to

control the transmitter to send a random access request message to the UE on a downlink control channel;

and

monitor a random access channel established on the downlink control channel, and control the transmitter to send a random access response message for allocation of a resource for a common control channel to the UE.

23. The apparatus of claim 21, wherein the controller is configured to

control the receiver to receive preamble information on an uplink random access channel;

establish time sync for an uplink channel if the received preamble information is not a dedicated preamble, and control the transmitter to send the UE a random access response message for allocation of a resource for a common control channel; and

control the receiver to receive information from the UE which includes C-RNTI, and control allocation of uplink/downlink radio resources for the UE if the C-RNTI is allocated to a small cell eNB (SeNB) for double connection.

24. The apparatus of claim 21, wherein the controller is configured to

control the controller to receive preamble information on an uplink random access channel;

control the transmitter to send a random access response message to the UE if the received preamble information is a dedicated preamble; and

allocate uplink/downlink radio resources for the UE.