Method of handling data transmission and reception in dual connectivity

Abstract

A method of handling data transmission and reception in dual connectivity, for a communication device in a wireless communication system is disclosed. The method comprises connecting to at least two evolved base station (eNBs) including a first eNB and a second eNB in the wireless communication system, being configured a packet data convergence protocol (PDCP) entity corresponding to at least two radio link control (RLC) entities including a first RLC entity for receiving/transmitting data from/to the first eNB and a second RLC entity for receiving/transmitting data from/to the second eNB, and when detecting a radio link failure a connection to the second eNB, not initiating a radio resource control (RRC) connection re-establishment procedure for connection recovery.

Claims

1. A method of handling data transmission and reception in dual connectivity, for a first base station in a wireless communication system, comprising: the first base station connecting to a communication device in the wireless communication system; the first base station being configured a packet data convergence protocol (PDCP) entity corresponding to at least two radio link control (RLC) entities including a first RLC entity of the first base station and a second RLC entity of a second base station in the wireless communication system for receiving/transmitting data from/to the communication device; and when the first base station detects a radio link failure on a connection from the first base station to the communication device, the first base station continuing data reception/transmission from/to the communication device via the second base station.

2. The method of claim 1, further comprising: the first base station transmitting a first PDCP status report indicating at least one missing PDCP SDU, to the communication device via the second base station, whereby the communication device transmits the at least one missing PDCP SDU to the first base station with the second base station when receiving the first PDCP status report.

3. The method of claim 1, further comprising: the first base station transmitting a first PDCP status report for indicating the radio link failure on the communication device to the communication device via the second base station, whereby the communication device transmits a second PDCP status report indicating at least one missing PDCP SDU to the first base station via the second base station.

4. The method of claim 3, further comprising: the first base station transmitting the at least one missing PDCP SDU to the communication device when receiving the second PDCP status report from the communication device.

5. The method of claim 1, wherein the first base station detects the radio link failure due to a timer expiry, wherein the timer expires because the first base station cannot receives a physical layer signal from the communication device in a time period or maximum number of transmissions has been reached in the RLC entity of the first base station.

6. A method of handling data transmission and reception in dual connectivity, for a first base station in a wireless communication system, comprising: the first base station connecting to a communication device in the wireless communication system; the first base station being configured a radio link control (RLC) entity which is configured for receiving/transmitting data from/to the communication device by a second base station connecting to the communication device in the wireless communication system; and when the first base station detects a radio link failure on a connection from the first base station to the communication device, the first base station notifying the second base station of the radio link failure, whereby the second base station continuing data reception/transmission from/to the communication device.

7. The method of claim 6, wherein the first base station detects the radio link failure due to a timer expiry, wherein the timer expires because the first base station cannot receives a physical layer signal from the communication device in a time period or maximum number of transmissions has been reached in the RLC entity of the first base station.

8. A first base station of a wireless communication system for handling data transmission and reception in dual connectivity, comprising: a memory for storing program code corresponding to a process; and a processor coupled to the memory, for processing the program code to execute the process; wherein the process comprises: connecting to a communication device in the wireless communication system; being configured a packet data convergence protocol (PDCP) entity corresponding to at least two radio link control (RLC) entities including a first RLC entity of the first base station and a second RLC entity of a second base station in the wireless communication system for receiving/transmitting data from/to the communication device; and when the first base station detects a radio link failure on a connection from the first base station to the communication device, continuing data reception/transmission from/to the communication device via the second base station.

9. The first base station of claim 8, wherein the process further comprises: transmitting a first PDCP status report indicating at least one missing PDCP SDU, to the communication device via the second base station, whereby the communication device transmits the at least one missing PDCP SDU to the first with the second base station when receiving the first PDCP status report.

10. The first base station of claim 8, wherein the process further comprises: transmitting a first PDCP status report for indicating the radio link failure on the communication device to the communication device via the second base station, whereby the communication device transmits a second PDCP status report indicating at least one missing PDCP SDU to the first base station via the second base station.

11. The first base station of claim 10, wherein the process further comprises: transmitting the at least one missing PDCP SDU to the communication device when receiving the second PDCP status report from the communication device.

12. The first base station of claim 8, wherein the first base station detects the radio link failure due to a timer expiry, wherein the timer expires because the first base station cannot receives a physical layer signal from the communication device in a time period or maximum number of transmissions has been reached in the RLC entity of the first base station.

13. A first base station of a wireless communication system for handling data transmission and reception in dual connectivity, comprising: a memory for storing program code corresponding to a process; and a processor coupled to the memory, for processing the program code to execute the process; wherein the process comprises: connecting to a communication device in the wireless communication system; being configured a radio link control (RLC) entity which is configured for receiving/transmitting data from/to the communication device by a second base station connecting to the communication device in the wireless communication system; and when the first base station detects a radio link failure on a connection from the first base station to the communication device, notifying the second base station of the radio link failure, whereby the second base station continuing data reception/transmission from/to the communication device.

14. The first base station of claim 13, wherein the first base station detects the radio link failure due to a timer expiry, wherein the timer expires because the first base station cannot receives a physical layer signal from the communication device in a time period or maximum number of transmissions has been reached in the RLC entity of the first base station.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a schematic diagram of protocol structure of a macro eNB, small eNB, and a UE in dual connectivity.

(2) FIG. 2 illustrates a schematic diagram of an exemplary communication device.

(3) FIGS. 3-5 are flowcharts of an exemplary process according to the present disclosure.

DETAILED DESCRIPTION

(4) FIG. 2 illustrates a schematic diagram of an exemplary communication device 20. The communication device 20 can be the UE, macro eNB, or small eNB shown in FIG. 1. The communication device 20 may include a processing means 200 such as a microprocessor or Application Specific Integrated Circuit (ASIC), a storage unit 210 and a communication interfacing unit 220. The storage unit 210 may be any data storage device that can store program code 214, for access by the processing means 200. Examples of the storage unit 210 include but are not limited to a subscriber identity module (SIM), read-only memory (ROM), flash memory, random-access memory (RAM), CD-ROMs, magnetic tape, hard disk, and optical data storage device. The communication interfacing unit 220 is preferably a radio transceiver and can exchange wireless signals with a network (i.e. E-UTRAN) according to processing results of the processing means 200.

(5) Please refer to FIG. 3, which is a flowchart of a process 30 according to an example of the present disclosure. The process 30 is utilized in the communication device 20 (i.e. a UE) for data transmission and reception in dual connectivity. The process 30 may be compiled into a program code 214 to be stored in the storage unit 210, and may include the following steps:

(6) Step 300: Start.

(7) Step 310: Connect to at least two eNBs including a first eNB and a second eNB in the wireless communication system.

(8) Step 320: Be configured a PDCP entity corresponding to at least two RLC entities including a first RLC entity for receiving/transmitting data from/to the first eNB and a second RLC entity for receiving/transmitting data from/to the second eNB.

(9) Step 330: When detecting a radio link failure on a connection to the second eNB, not initiate a RRC connection re-establishment procedure for connection recovery.

(10) Step 340: End.

(11) According to the process 30, the UE is configured connections to a first eNB and a second eNB to receive data from the first eNB and second eNB, wherein the first eNB may be a macro eNB and the second eNB may be a small eNB. When the UE detects a radio link failure on one of the connections to the two eNBs, the UE does not initiate a RRC connection re-establishment procedure for recovering the connections to the first eNB and the second eNB. Thus, the UE can continue receiving data from the eNB which no radio link failure is detected on the other connection to. On the other hand, the UE may transmit data to the first eNB and the second eNB. If the UE detects a radio link failure on one of the two connections to the two eNBs, the UE does not initiate the RRC connection re-establishment procedure, but continues transmitting data to the eNB which no radio link failure is detected on the other connection to. With such manner, the UE can perform data reception/transmission without suspension since there is only one connection has the radio link failure, so as to avoid resource wasting.

(12) Moreover, the UE may send a first PDCP status report indicating at least one missing PDCP SDU to the eNB which no radio link failure is detected on the connection to. When the eNB receives the PDCP status report, the eNB transmits the at least one missing PDCP SDU to the UE.

(13) Note that, the UE may detect the radio link failure on a connection to an eNB due to expiry of a timer T310 for the eNB, random access problem in a MAC entity for the eNB, or maximum number of transmissions has been reached in a RLC entity for data transmission to the eNB. Moreover, when the UE detects the radio link failure on a connection to the first eNB, the UE sends a RRC message to indicate the radio link failure on the connection to the first eNB, to the second eNB. When the second eNB receives the RRC message, the second eNB transmits a PDCP status report indicating at least one missing PDCP SDU to the UE. In addition, when the UE receives the PDCP status report, the UE transmits the at least one missing PDCDP SDU to the second eNB.

(14) In an embodiment, the UE may send a first PDCP status report for indicating the radio link failure on the connection to the first eNB, to the second eNB. When the second eNB receives the first PDCP status report, the second eNB transmits a second PDCP status report indicating at least one missing PDCP SDU to the UE. When the UE receives the second PDCP status report, the UE transmits the at least one missing PDCDP SDU to the second eNB.

(15) Note that, the PDCP entity of the UE is used to transmit/receive either RRC message or internet protocol (IP) packets. In addition, the first and second RLC entities of the UE for transmitting/receiving data to the first eNB and second eNB are both in the same mode (i.e. an acknowledged mode (AM) or unacknowledged mode (UM)).

(16) Please refer to FIG. 4, which is a flowchart of a process 40 according to an example of the present disclosure. The process 40 is utilized in the communication device 20 (i.e. a macro eNB) for data transmission and reception in dual connectivity. The process 40 may be compiled into a program code 214 to be stored in the storage unit 210, and may include the following steps:

(17) Step 400: Start.

(18) Step 410: Connect to a UE in the wireless communication system.

(19) Step 420: Be configured a PDCP entity corresponding to at least two radio link control (RLC) entities including a first RLC entity of the macro eNB and a second RLC entity of a small eNB in the wireless communication system for receiving/transmitting data from/to the UE.

(20) Step 430: When detecting a radio link failure on a connection to the UE, continue data reception/transmission from/to the UE via the small eNB.

(21) Step 440: End.

(22) According to the process 40, when the macro eNB detects a radio link failure on the connection to the UE, the macro eNB keeps receiving data from the UE with the small eNB. And/Or, the macro eNB may keep transmitting data to the UE with the small eNB when the macro eNB detects the radio link failure on the connection to the UE. With such manner, data reception/transmission is not suspended since the macro eNB can receive or transmit data from or to the UE through the small eNB.

(23) In addition, the macro eNB sends a PDCP status report indicating at least one missing PDCP SDU to the UE. When the UE receives the PDCP status report, the UE transmits the at least one missing PDCP SDU to the macro eNB via the small eNB.

(24) Note that, the macro eNB may detect the radio link failure on the connection to the UE due to expiry of a timer for the UE, where the timer expires because the macro eNB cannot receives physical layer signal (e.g. channel state information (e.g. channel quality indicator)) from the UE in a time period, or maximum number of transmissions has been reached in the RLC entity of the macro eNB. Moreover, when the macro eNB detects the radio link failure on the connection to the UE, the macro eNB may send a first PDCP status report for indicating the radio link failure, to the UE via the small eNB. When the UE receives the first PDCP status report, the UE transmits a second PDCP status report indicating at least one missing PDCP SDU to the macro eNB via the small eNB. When the macro eNB receives the second PDCP status report, the macro eNB transmits the at least one missing PDCDP SDU to the UE via the small eNB.

(25) Note that, a first RLC entity of a macro eNB and a second RLC entity of a small eNB for transmitting/receiving data to the UE are both in the same mode (i.e. an acknowledged mode (AM) or unacknowledged mode (UM)).

(26) Please refer to FIG. 5, which is a flowchart of a process 50 according to an example of the present disclosure. The process 50 is utilized in the communication device 20 (i.e. a small eNB) for data transmission and reception in dual connectivity. The process 50 may be compiled into a program code 214 to be stored in the storage unit 210, and may include the following steps:

(27) Step 500: Start.

(28) Step 510: Connect to a UE in the wireless communication system.

(29) Step 520: Be configured a radio link control (RLC) entity which is configured for receiving/transmitting data from/to the UE by a PDCP entity of a macro eNB connecting to the UE in the wireless communication system.

(30) Step 530: When detecting a radio link failure on a connection to the UE, notify the macro eNB of the radio link failure, whereby the macro eNB continuing data reception/transmission from/to the UE.

(31) Step 540: End.

(32) According to the process 50, when the small eNB detects a radio link failure on the connection to the UE, the small eNB notifies the macro eNB the radio link failure and the macro eNB continues receiving/transmitting data from/to the UE. With such manner, data reception/transmission is not suspended since only connection to the small eNB has radio link failure. In other words, the UE can continuously receive/transmit data from/to the macro eNB.

(33) In addition, the macro eNB may send a PDCP status report indicating at least one missing PDCP SDU to the UE. When the UE receives the PDCP status report, the UE transmits the at least one missing PDCP SDU to the macro eNB. Similarly, the UE can send a PDCP status report indicating at least one missing PDCP SDU to the macro eNB. When the macro eNB receives the PDCP status report, the macro eNB transmits the at least one missing PDCP SDU to the UE.

(34) Note that, the small eNB may detect the radio link failure on the connection to the UE due to expiry of a timer for the UE, where the timer expires because the small eNB cannot receives physical layer signal (e.g. channel state information (e.g. channel quality indicator)) from the UE in a time period, or maximum number of transmissions toward to a RLC entity of the UE has been reached in the RLC entity of the small eNB.

(35) The abovementioned steps of the processes including suggested steps can be realized by means that could be a hardware, a firmware known as a combination of a hardware device and computer instructions and data that reside as read-only software on the hardware device or an electronic system. Examples of hardware can include analog, digital and mixed circuits known as microcircuit, microchip, or silicon chip. Examples of the electronic system can include a system on chip (SOC), system in package (SiP), a computer on module (COM) and the communication device 20.

(36) In conclusion, the present invention provides a data transmission and reception in dual connectivity, so as to avoid resource wasting.

(37) Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.