DISCOVERY SIGNALS AND NETWORK SYNCHRONIZATION SIGNALS DESIGN IN LTE

• US 20150215761A1
• Filed: 12/29/2014
• Published: 07/30/2015
• 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
• Granted Patent: US 9,832,629 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 a first reference signal for at least one of discovery or measurement, and a second reference signal for synchronization, wherein both the first reference signal and the second reference signal are based on a same type of reference signal;

transmitting the first reference signal in one or more symbols of a first set of subframes; and

transmitting the second reference signal in one or more symbols of a second set of subframes, where the first set of subframes and the second set of subframes differ at least by one subframe.

2. The method of claim 1, further comprising refraining from transmitting during at least one of a first symbol or a second symbol in at least a subset of subframes in the second set of subframes,

wherein the first symbol precedes the one or more symbols in which the second reference signal is transmitted and the second symbol is subsequent to the one or more symbols in which the second reference signal is transmitted.

3. The method of claim 2, wherein the first symbol is a beginning symbol in a subframe and the second symbol is an ending symbol in a subframe.

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

5. The method of claim 4, further comprising transmitting an instruction to a user equipment (UE) to refrain from transmitting signals in the at least one subframe in the second set of subframes.

6. The method of claim 1, wherein the first reference signal allows a user equipment (UE) near the first base station to discover the first base station, and wherein the second reference signal allows a second base station to synchronize with the first base station.

7. The method of claim 1, wherein the same type of reference signal is 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).

8. The method of claim 1, further comprising configuring a bandwidth for at least one of the first reference signal or the second reference signal, wherein at least one of the first reference signal or the second reference signal is transmitted using the configured bandwidth.

9. The method of claim 8, further comprising determining a downlink system bandwidth of the first BS, wherein the configured bandwidth is less than the downlink system bandwidth.

10. The method of claim 8, further comprising transmitting one or more parameters associated with at least one of the first reference signal or the second reference signal to another node, the one or more parameters comprising at least one of

the configured bandwidth,

information identifying a subframe that includes at least one of the first reference signal or the second reference signal,

a stratum level, or

an energy per resource element (EPRE) of at least one of the first reference signal or the second reference signal.

11. The method of claim 1, further comprising determining a cyclic prefix for at least one of the first reference signal or the second reference signal, wherein the determined cyclic prefix is different from a cyclic prefix of a common reference signal.

12. The method of claim 1, wherein at least one of the first set of subframes or the second set of subframes is based on a periodic configuration.

13. The method of claim 12, at least the first reference signal or the second reference signal is transmitted in two or more consecutive subframes.

14. A method of wireless communication for a user equipment (UE) comprising:

receiving at least one of a first reference signal for at least one of discovery or measurement or a second reference signal for synchronization, at least one of the first or second reference signals having a bandwidth configured by a base station (BS); and

detecting at least one BS based on at least one of the first or second reference signals.

15. The method of claim 14, wherein the bandwidth is less than a downlink system bandwidth.

16. The method of claim 14, further comprising receiving one or more parameters associated with at least one of the first reference signal or the second reference signal from the BS, the one or more parameters comprising at least one of

the configured bandwidth,

information identifying a subframe that includes at least one of the first reference signal or the second reference signal,

a stratum level, or

an energy per resource element (EPRE) of at least one of the first reference signal or the second reference signal.

17. The method of claim 16, wherein the first and second reference signals are based on a same type of reference signal, the same type of reference signal being 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. A method of wireless communication for a first base station (BS) comprising:

determining, by the first BS, one or more symbols of a 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;

refraining, by the first BS, from transmitting during the determined one or more symbols; and

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

19. The method of claim 18, further comprising synchronizing with at least the second base station based on the received at least one reference signal.

20. The method of claim 18, wherein each of the 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).

21. The method of claim 18, 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).

22. A first base station (BS) for wireless communication, comprising:

a memory; and

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

determine a first reference signal for at least one of discovery or measurement, and a second reference signal for synchronization, wherein both the first reference signal and the second reference signal are based on a same type of reference signal;

transmit the first reference signal in one or more symbols of a first set of subframes; and

transmit the second reference signal in one or more symbols of a second set of subframes, where the first set of subframes and the second set of subframes differ at least by one subframe.

23. The first BS of claim 22, wherein the at least one processor is further configured to refrain from transmitting during at least one of a first symbol or a second symbol in at least a subset of subframes in the second set of subframes, and

wherein the first symbol precedes the one or more symbols in which the second reference signal is transmitted and the second symbol is subsequent to the one or more symbols in which the second reference signal is transmitted.

24. The first BS of claim 23, wherein the first symbol is a beginning symbol in a subframe and the second symbol is an ending symbol in a subframe.

25. The first BS of claim 22, wherein at least one subframe in the second set of subframes is one of a special subframe or an uplink (UL) subframe, wherein at least a portion of the at least one subframe is allocated for transmission of UL signals by a user equipment (UE).

26. The first BS of claim 25, wherein the at least one processor is further configured to transmit an instruction to a user equipment (UE) to refrain from transmitting signals in the at least one subframe in the second set of subframes.

27. The first BS of claim 22, wherein the first reference signal allows a user equipment (UE) near the first base station to discover the first base station, and wherein the second reference signal allows a second base station to synchronize with the first base station.

28. The first BS of claim 22, wherein the same type of reference signal is a positioning reference signal (PRS).

29. The first BS of claim 22, wherein the at least one processor is further configured to configure a bandwidth for at least one of the first reference signal or the second reference signal, and wherein at least one of the first reference signal or the second reference signal is transmitted using the configured bandwidth.

30. The first BS of claim 29, wherein the at least one processor is further configured to determine a downlink system bandwidth of the first BS, wherein the configured bandwidth is less than the downlink system bandwidth.