Device, network, and method for utilizing a downlink discovery reference signal

• US 9,509,469 B2
• Filed: 04/03/2014
• Issued: 11/29/2016
• Est. Priority Date: 04/04/2013
• Status: Active Grant

• Current Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Inventors: Cheng, Qian, Liu, Jialing, Xiao, Weimin
• Primary Examiner(s): Anwar, Mohammad
• Assistant Examiner(s): Dewan, Sanjay K
• Application Number:
  US14/244,515
• Publication Number:
  US 20140301301A1
• Time in Patent Office: 971 Days
• Field of Search: 370/329
• US Class Current: 1/1
• CPC Class Codes: H04L 5/00 Arrangements affording multiple use of the transmission path
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0073 Allocation arrangements that take into account other cell interferences for intercell interference mitigation or co-ordination in orthogonal multiplex systems H04J11/005
• CPC Class Codes: H04L 5/1469 using time-sharing
• CPC Class Codes: H04W 36/0072 of resource information of target access point
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B

Abstract

User equipments can achieve quick channel synchronization when establishing a connection to base stations transitioning from a sleep mode to an active mode by using discovery resource signal (DRS) processing results and cell reference signal (CRS) processing results to establish channel synchronization with a CRS antenna port. More specifically, the user equipment may be notified that the CRS antenna port and DRS antenna port are quasi-co-located (QCL), and then use DRS processing results in conjunction with CRS processing results to obtain faster channel synchronization with a CRS antenna port. This may be particularly beneficial when the target BS is transitioned from a sleep mode to an active mode in order to accept a handover of the user equipment.

Claims

1. A method for signaling comprising:

receiving, by a user equipment (UE), a discovery reference signal (DRS) transmission over a first antenna port and a cell-specific reference signal (CRS) transmission over a second antenna port, the first antenna port being different from the second antenna port, the DRS transmission being a different type of signal than the CRS transmission;

processing, by the UE, the DRS transmission to obtain a DRS processing result;

processing, by the UE, the CRS transmission to obtain a CRS processing result, the DRS transmission being received prior to the CRS transmission; and

using, by the UE, the DRS processing result in conjunction with the CRS processing result to establish channel synchronization with the second antenna port when the first antenna port and the second antenna port are quasi-co-located (QCL).

2. The method of claim 1, further comprising:

using, by the UE, the CRS processing result to establish channel synchronization with the second antenna port without using the DRS processing result to establish the channel synchronization when the first antenna port and the second antenna port are not QCL.

3. The method of claim 1, further comprising:

receiving, by the UE, a message from a network device, the message indicating that the first antenna port and the second antenna port have a QCL relationship.

4. The method of claim 1, further comprising:

determining, by the UE, that the first antenna port and the second antenna port are QCL according to a priori information of the UE.

5. The method of claim 1, further comprising:

receiving, by the UE, a handover message indicating that the UE is being handed over from a source cell to a target cell, and wherein the DRS transmission and the CRS transmission are communicated by the target cell.

6. The method of claim 5, wherein the DRS transmission is communicated over a first set of resources mapped to the first antenna port, and wherein the CRS transmission is communicated over a second set of resources mapped to the second antenna port, the first set of resources being different than the second set of resources.

7. The method of claim 5, further comprising:

communicating the DRS processing result to a network device prior to receiving the handover message, the DRS processing result being obtained during a first period, wherein the target cell operates in a sleep mode during the first period, and wherein the target cell is configured to communicate the DRS transmission without communicating the CRS when operating in a sleep mode.

8. The method of claim 7, wherein communicating the DRS processing result to the network device prompts the target cell to transition from the sleep mode to an active mode, and wherein the target cell is configured to transmit at least the CRS transmission when operating in the active mode.

9. The method of claim 5, wherein the target cell and the source cell are low power nodes.

10. The method of claim 5, wherein the target cell is a low power node and the source cell is a macro base station.

11. The method of claim 5, wherein the source cell and the target cell are associated with a common base station configured for carrier aggregation.

12. A user equipment comprising:

a processor, and

a non-transitory computer readable storage medium coupled to the processor and storing programming for execution by the processor, the programming including instructions to;

receive a discovery reference signal (DRS) transmission over a first antenna port and a cell-specific reference signal (CRS) transmission over a second antenna port, the

first antenna port being different from the second antenna port, the DRS transmission being a different type of signal than the CRS transmission;

process the DRS transmission to obtain a DRS processing result;

process the CRS transmission to obtain a CRS processing result, the DRS transmission being received prior to the CRS transmission; and

use the DRS processing result in conjunction with the CRS processing result to establish channel synchronization with the second antenna port when the first antenna port and the second antenna port are quasi-co-located (QCL).

13. The user equipment of claim 12, wherein the programming further includes instructions to:

communicate the DRS processing result to a network device prior to processing the CRS transmission, the DRS processing result being obtained during a period in which a target cell operates in a sleep mode, wherein the target cell is configured to communicate the DRS transmission without communicating the CRS when operating in a sleep mode; and

receive a handover message after communicating the DRS processing result to the network device, the handover message indicating that the user equipment is being handed over from a source cell to the target cell, and wherein the DRS transmission and the CRS transmission are communicated by the target cell, wherein communicating the DRS processing result to the network device prompts the target cell to transition from the sleep mode to an active mode, and wherein the target cell is configured to transmit at least the CRS transmission when operating in the active mode.

14. A method for discovery reference signaling, the method comprising:

sending, by a network device, a first message to a user equipment, the first message indicating that a discovery resource signal (DRS) transmission is being communicated over a first antenna port, wherein the DRS transmission is communicated-by a target cell; and

sending, by the network device, at least one additional message to the user equipment, the at least one additional message indicating both that a cell-specific reference signal (CRS) transmission is being communicated over a second antenna port, and that the second antenna port is quasi-co-located with the first antenna port, the second antenna port being different than the first antenna port, wherein the CRS transmission is communicated after the DRS transmission by the target cell, and wherein the at least one additional message indicating that that the second antenna port is quasi-co-located with the first antenna port prompts the user equipment to use a DRS processing result obtained from the DRS transmission to establish channel synchronization with the second antenna port.

15. The method of claim 14, wherein the DRS transmission is communicated over a first set of resources mapped to the first antenna port, and wherein the CRS transmission is communicated over a second set of resources mapped to the second antenna port, the first set of resources being different than the second set of resources.

16. The method of claim 14, wherein the DRS transmission and the CRS transmission are communicated by the target cell, the DRS transmission being configured with a longer duty cycle than the CRS transmission.

17. The method of claim 14, wherein the at least one additional message includes a handover message indicating that the user equipment is being handed over from a source cell to the target cell.

18. The method of claim 17, further comprising:

receiving, by the network device, a measurement report from the user equipment prior to sending the handover message to the user equipment, the measurement report comprising DRS processing results obtained from the DRS transmission during a first period, wherein the target cell operates in a sleep mode during the first period, and wherein the target cell is configured to communicate the DRS transmission without communicating the CRS transmission when operating in a sleep mode.

19. The method of claim 18, further comprising:

prompting the target cell to transition from the sleep mode to an active mode when the DRS processing results satisfy a criteria, wherein the target cell is configured to transmit at least the CRS transmission when operating in the active mode.

20. The method of claim 17, wherein the source cell is a macrocell, and wherein the target cell is a low power node.

21. The method of claim 17, wherein the source cell and the target cell are neighboring low power nodes.

22. The method of claim 17, wherein the source cell and the target cell are associated with a common base station configured for carrier aggregation.

23. A network device comprising:

a processor; and

a non-transitory computer readable storage medium storing programming for execution by the processor, the programming including instructions to;

send a first message to a user equipment, the first message indicating that a discovery resource signal (DRS) transmission is being communicated over a first antenna port, wherein the DRS transmission is communicated by a target cell; and

send at least one additional message to the user equipment, the at least one additional message indicating both that a cell-specific reference signal (CRS) transmission is being communicated over a second antenna port, and that the second antenna port is quasi-co-located with the first antenna port, the second antenna port being different than the first antenna port, wherein the CRS transmission is communicated after the DRS transmission by the target cell, and wherein the at least one additional message indicating that the second antenna port is quasi-co-located with the first antenna port prompts the user equipment to use a DRS processing result obtained from the DRS transmission to establish channel synchronization with the second antenna port.

24. The network device of claim 23, wherein the at least one additional message includes a handover message indicating that the user equipment is being handed over from a source cell to the target cell, and wherein the programming further includes instructions to:

receive a measurement report from the user equipment prior to sending the handover message to the user equipment, the measurement report comprising a DRS processing result obtained from the DRS transmission during a period in which the target cell operates in a sleep mode, wherein the target cell is configured to communicate the DRS transmission without communicating the CRS transmission when operating in a sleep mode; and

prompting the target cell to transition from the sleep mode to an active mode when the DRS processing result satisfies a criteria, wherein the target cell is configured to transmit at least the CRS transmission when operating in the active mode.

25. A method for communicating in a wireless network, the method comprising:

receiving, by a user equipment (UE), a first reference signal (RS) associated with a cell, wherein the first RS is different than a cell-specific reference signal (CRS) associated with the cell, and wherein the first RS is received at a different time than the CRS; and

performing, by the UE, a radio resource management (RRM) measurement based at least on the first RS without assuming the CRS is carried in one or more downlink subframes following a subframe carrying the first RS.

26. The method of claim 25, wherein performing the RRM measurement further comprises:

performing the RRM measurement based on the first RS under the assumption that a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical downlink shared channel (PDSCH), a physical downlink control channel (PDCCH), an enhanced physical downlink control channel (EPDCCH), a demodulation reference signal (DMRS), and a channel state information reference signal (CSI-RS) associated with the cell are not transmitted in the one or more downlink subframes following the subframe carrying the first RS.

27. The method of claim 25, wherein the UE assumes that the PSS, the SSS, the CRS, the PDSCH, the PDCCH, the EPDCCH, the DMRS, and the CSI-RS associated with the cell are not transmitted in the one or more downlink subframes following the subframe carrying the first RS when a downlink transmission of the cell is turned off.

28. The method of claim 25, wherein the UE does not assume any other signals or physical channels are present in the one or more downlink subframes following the subframe carrying the first RS for the RRM measurement based on the first RS.

29. The method of claim 25, wherein a first antenna port associated with the first RS is quasi-co-located (QCL) with a second antenna port associated with the CRS.

30. The method of claim 29, wherein the first antenna port is QCL with the second antenna port with respect to at least the average delay and Doppler shift.

31. A method for communicating in a wireless network, the method comprising:

transmitting, by a base station, a configuration signaling to a user equipment (UE), the configuration signaling configuring the UE to perform a radio resource management (RRM) measurement based at least on a first reference signal (RS) without assuming that a cell-specific reference signal (CRS) associated with the cell is carried in one or more downlink subframes following a subframe carrying the first RS, the first RS being different than the CRS, and the first RS being communicated at a different time than the CRS;

transmitting, by the base station, the first RS to the UE; and

suspending, by the base station, transmission of the CRS in one or more downlink subframes following a subframe carrying the first RS.