Discovery signals and network synchronization signals design in LTE

• US 9,985,762 B2
• Filed: 06/26/2017
• Issued: 05/29/2018
• Est. Priority Date: 01/28/2014
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Chen, Wanshi, Gaal, Peter, Damnjanovic, Aleksandar, Wang, Michael Mao
• Primary Examiner(s): Moutaouakil, Mounir
• Application Number:
  US15/633,621
• Publication Number:
  US 20170295002A1
• Time in Patent Office: 337 Days
• CPC Class Codes: H04L 1/1822 involving configuration of automatic repeat request [ARQ] with parallel processes
• 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: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 76/14 Direct-mode setup
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals

Abstract

Base stations (such as small cells) may support active and dormant states. To facilitate state transitions, these cells may transmit discovery signals. The transmission design of both discovery signals and network synchronization signals from small cells should provide for regular periodicity, while supporting the benefit of transitioning between active and dormant states. Disclosed is a method, a computer program product, and an apparatus that determine a first reference signal for at least one of discovery or measurement, and a second reference signal for synchronization, where both the first reference signal and the second reference signal are based on a same type of reference signal.

Claims

1. A method of wireless communication for a first base station (BS) comprising:

determining, by the first BS, one or more symbols of a first set of subframes in which at least one reference signal is to be received, wherein the at least one reference signal is for synchronization with at least a second BS, wherein discovery reference signals and the at least one reference signal for synchronization are separately managed;

refraining, by the first BS, from transmitting during the determined one or more symbols and during at least one of a first symbol or a second symbol in at least a subset of subframes in the first set of subframes, the first symbol preceding the one or more symbols in which the at least one reference signal for synchronization is received from the second BS and the second symbol being subsequent to the one or more symbols in which the at least one reference signal for synchronization is received from the second BS;

transmitting, by the first BS, a discovery reference signal during a second set of one or more symbols when the at least second BS transmits a second discovery reference signal; and

receiving the at least one reference signal for synchronization in the one or more symbols of the first set of subframes.

2. The method of claim 1, further comprising:

synchronizing with at least the second BS based on the received at least one reference signal.

3. The method of claim 1, wherein each of the first set of subframes is one of a special subframe or an uplink (UL) subframe, at least a portion of the special subframe or the UL subframe being allocated for transmission of UL signals by a user equipment (UE).

4. The method of claim 1, wherein the at least one reference signal is based on at least one of:

a cell-specific reference signal (CRS),

a primary synchronization signal (PSS),

a secondary synchronization signal (SSS);

or

a positioning reference signal (PRS).

5. The method of claim 1, wherein the at least one reference signal is based on a positioning reference signal (PRS).

6. The method of claim 5, further comprising:

using the at least one reference signal based on the PRS to synchronized with the second BS.

7. The method of claim 1, wherein the discovery reference signal and the at least one reference signal for synchronization are based on a same type of reference signal.

8. The method of claim 1, wherein the discovery reference signal is transmitted in a same subframe across cells and the at least one reference signal for synchronization is transmitted in a subframe based on a stratum level of the second BS.

9. The method of claim 1, wherein the at least one reference signal for synchronization is received in a guard period of a special subframe.

10. The method of claim 9, wherein the at least one reference signal for synchronization comprises a truncated version of a positioning reference signal (PRS).

11. The method of claim 1, further comprising:

transmitting a synchronization reference signal in a subframe when the first base station is not performing network listening.

12. The method of claim 1, wherein the at least one reference signal for synchronization comprises periodic transmission instances spanning an integer number of subframes, wherein the integer number is greater than one, the method further comprising:

receiving an indication of the integer number.

13. The method of claim 12, wherein the at least one reference signal for synchronization comprises periodic transmission instances spanning the integer number of consecutive subframes.

14. An apparatus for wireless communication at a first base station (BS), comprising:

means for determining, by the first BS, one or more symbols of a first set of subframes in which at least one reference signal is to be received, wherein the at least one reference signal is for synchronization with at least a second BS, wherein discovery reference signals and the at least one reference signal for synchronization are separately managed;

means for refraining, by the first BS, from transmitting during the determined one or more symbols and during at least one of a first symbol or a second symbol in at least a subset of subframes in the first set of subframes, the first symbol preceding the one or more symbols in which the at least one reference signal for synchronization is received from the second BS and the second symbol being subsequent to the one or more symbols in which the at least one reference signal for synchronization is received from the second BS;

means for transmitting, by the first BS, a discovery reference signal during a second set of one or more symbols when the at least second BS transmits a second discovery reference signal; and

means for receiving the at least one reference signal for synchronization in the one or more symbols of the first set of subframes.

15. The apparatus of claim 14, further comprising:

means for synchronizing with at least the second BS based on the received at least one reference signal.

16. The apparatus of claim 14, wherein each of the first set of subframes is one of a special subframe or an uplink (UL) subframe, at least a portion of the special subframe or the UL subframe being allocated for transmission of UL signals by a user equipment (UE).

17. The apparatus of claim 14, wherein the at least one reference signal is based on at least one of:

a cell-specific reference signal (CRS),

a primary synchronization signal (PSS),

a secondary synchronization signal (SSS);

or

a positioning reference signal (PRS).

18. The apparatus of claim 14, wherein the at least one reference signal is based on a positioning reference signal (PRS).

19. An apparatus for wireless communication at a first base station (BS), comprising:

a memory; and

at least one processor coupled to the memory and configured to;

determine, by the first BS, one or more symbols of a first set of subframes in which at least one reference signal is to be received, wherein the at least one reference signal is for synchronization with at least a second BS, wherein discovery reference signals and the at least one reference signal for synchronization are separately managed;

refrain, by the first BS, from transmitting during the determined one or more symbols and during at least one of a first symbol or a second symbol in at least a subset of subframes in the first set of subframes, the first symbol preceding the one or more symbols in which the at least one reference signal for synchronization is received from the second BS and the second symbol being subsequent to the one or more symbols in which the at least one reference signal for synchronization is received from the second BS;

transmit, by the first BS, a discovery reference signal during a second set of one or more symbols when the at least second BS transmits a second discovery reference signal; and

receive the at least one reference signal for synchronization in the one or more symbols of the first set of subframes.

20. The apparatus of claim 19, wherein the at least one processor is further configured to:

synchronize with at least the second BS based on the received at least one reference signal.

21. The apparatus of claim 19, wherein each of the first set of subframes is one of a special subframe or an uplink (UL) subframe, at least a portion of the special subframe or the UL subframe being allocated for transmission of UL signals by a user equipment (UE).

22. The apparatus of claim 19, wherein the at least one reference signal is based on at least one of:

a cell-specific reference signal (CRS),

a primary synchronization signal (PSS),

a secondary synchronization signal (SSS);

or

a positioning reference signal (PRS).

23. The apparatus of claim 19, wherein the at least one reference signal is based on a positioning reference signal (PRS).

24. A non-transitory computer-readable medium storing computer executable code for wireless communication at a first base station (BS), comprising code to:

determine, by the first BS, one or more symbols of a first set of subframes in which at least one reference signal is to be received, wherein the at least one reference signal is for synchronization with at least a second BS, wherein discovery reference signals and the at least one reference signal for synchronization are separately managed;

refrain, by the first BS, from transmitting during the determined one or more symbols and during at least one of a first symbol or a second symbol in at least a subset of subframes in the first set of subframes, the first symbol preceding the one or more symbols in which the at least one reference signal for synchronization is received from the second BS and the second symbol being subsequent to the one or more symbols in which the at least one reference signal for synchronization is received from the second BS;

transmit, by the first BS, a discovery reference signal during a second set of one or more symbols when the at least second BS transmits a second discovery reference signal; and

receive the at least one reference signal for synchronization in the one or more symbols of the first set of subframes.

25. The computer-readable medium of claim 24, further comprising code to:

synchronize with at least the second BS based on the received at least one reference signal.

26. The computer-readable medium of claim 24, wherein each of the first set of subframes is one of a special subframe or an uplink (UL) subframe, at least a portion of the special subframe or the UL subframe being allocated for transmission of UL signals by a user equipment (UE).

27. The computer-readable medium of claim 24, wherein the at least one reference signal is based on at least one of:

a cell-specific reference signal (CRS),

a primary synchronization signal (PSS),

a secondary synchronization signal (SSS);

or

a positioning reference signal (PRS).

28. The computer-readable medium of claim 24, wherein the at least one reference signal is based on a positioning reference signal (PRS).