Downlink Procedures For LTE/LTE-A Communication Systems With Unlicensed Spectrum

• US 20150049741A1
• Filed: 08/14/2014
• Published: 02/19/2015
• Est. Priority Date: 08/16/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Chen, Wanshi, Gaal, Peter, Malladi, Durga Prasad, Luo, Tao, Damnjanovic, Aleksandar, Bhushan, Naga, Ji, Tingfang, Wei, Yongbin
• Granted Patent: US 9,591,644 B2
• Time in Patent Office: Days
• US Class Current: 370/336
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 48/12 using downlink control channel
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 56/0005 synchronizing of arrival of multiple uplinks
• 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 72/0453 Resources in frequency domain, e.g. a carrier in FDMA

Abstract

Long term evolution (LTE)/LTE-Advanced (LTE-A) deployments with unlicensed spectrum leverage more efficient LTE communication aspects over unlicensed spectrum, such as over WIFI radio access technology. In order to accommodate such communications, various downlink procedures may be modified in order to handle communications between licensed and unlicensed spectrum with LTE/LTE-A deployments with unlicensed spectrum.

Claims

1. A method of wireless communication, comprising:

generating, at a base station configured to transmit orthogonal frequency divisional multiple access (OFDMA) communication signals over at least an unlicensed spectrum, at least one of;

one or more synchronization signals, or a system broadcast signal for transmission;

determining, by the base station, a non-clear channel assessment (non-CCA) subframe for transmission of the at least one of;

the one or more synchronization signals, or the system broadcast signal; and

transmitting, by the base station, the at least one of;

the one or more synchronization signals, or the system broadcast signal in the non-CCA subframe.

2. The method of claim 1, wherein the transmission in the non-CCA subframe is associated with a duration and a periodicity, and a ratio between the duration and the periodicity is no more than 5%.

3. The method of claim 1, further including:

detecting, by the base station, a clear CCA in a CCA subframe; and

transmitting, by the base station, at least one other of;

the one or more synchronization signals, or one other system broadcast signal in the CCA subframe in response to detecting the clear CCA.

4. The method of claim 1, wherein the non-CCA subframe in which the at least one of:

the one or more synchronization signals, or one or more system broadcast signals is transmitted is staggered over different carriers.

5. The method of claim 1, wherein the system broadcast signal comprises at least one of:

an indication of a frame structure for at least one unlicensed carrier of the base station,

a network identifier,

a bandwidth identifier identifying one of a plurality of available bandwidths associated with the base station,

an indication of a number of carriers in the unlicensed spectrum,

a number of reference signal ports,

one or more parameters associated with a random access procedure,

a system frame number, or,

information related to control channels, wherein the information comprises at least one of a size or a location of the control channels.

6. The method of claim 5, wherein the frame structure is at least one of:

a downlink-only frame structure, a mixed downlink/uplink frame structure, or an uplink-only frame structure.

7. The method of claim 1, wherein the base station includes at least one licensed carrier, and is in communication with at least one user equipment configured with one of:

a supplemental downlink (SDL), or carrier aggregation (CA) operation using a carrier in the unlicensed spectrum.

8. The method of claim 1, where the at least one of:

the one or more synchronization signals, or the system broadcast signal, is a wideband signal spanning more than 1.4 MHz.

9. The method of claim 1, wherein the transmission of the non-CCA subframe is associated with an offset, and the offset is a function of a network identifier.

10. The method of claim 1, further including, in the non-CCA subframe, at least one of:

cell-specific reference signals (CRS);

channel-state information reference signals (CSI-RS);

reference signals for enhanced physical broadcast channel (EPBCH);

or

channel user pilot signals (CUPS)/channel user beacon signals (CUBS).

11. The method of claim 1, wherein a duration of the unlicensed band cyclic prefix is less than or equal to a normal cyclic prefix associated with communications over licensed spectrum.

12. A method of wireless communication, comprising:

receiving, at a user equipment configured to receive orthogonal frequency divisional multiple access (OFDMA) communication signals over at least an unlicensed spectrum, at least one of;

one or more synchronization signals, or a system broadcast signal in a non-clear channel assessment (non-CCA) subframe from a base station; and

communicating, by the user equipment, with the base station based on the received at least one of;

one or more synchronization signals, or a system broadcast signal.

13. The method of claim 12, wherein the receiving in the non-CCA subframe is associated with a duration and a periodicity, and a ratio between the duration and the periodicity is no more than 5%.

14. The method of claim 12, further including:

detecting, by the user equipment, a clear CCA in a CCA subframe; and

receiving, by the user equipment, at least one other of;

the one or more synchronization signals, or one other system broadcast signal in the CCA subframe in response to detecting the clear CCA.

15. The method of claim 12, wherein the non-CCA subframe in which the at least one of:

the one or more synchronization signals, or one or more system broadcast signals, is received is staggered over different carriers.

16. The method of claim 12, wherein the system broadcast signal includes at least one of:

an indication of a frame structure for at least one unlicensed carrier of the base station,

a network identifier,

a bandwidth identifier identifying one of a plurality of available bandwidths associated with the base station,

an indication of a number of carriers in the unlicensed spectrum,

a number of reference signal ports,

one or more parameters associated with a random access procedure,

a system frame number, or,

information related to control channels, wherein the information comprises at least one of a size or a location of the control channels.

17. The method of claim 16, wherein the frame structure is at least one of:

a downlink-only frame structure, a mixed downlink/uplink frame structure, or an uplink-only frame structure.

18. The method of claim 12, wherein the user equipment is in communication with the base station having at least one licensed carrier, wherein the user equipment is configured with one of:

a supplemental downlink (SDL) or carrier aggregation (CA) operation using a carrier in the unlicensed spectrum.

19. The method of claim 12, wherein the at least one of:

the one or more synchronization signals, or the system broadcast signal, is a wideband signal spanning more than 1.4 MHz.

20. The method of claim 12, wherein the receiving of the non-CCA subframe is associated with an subframe offset, and the subframe offset is a function of a network identifier.

21. The method of claim 12, further including, in the non-CCA subframe, at least one of:

cell-specific reference signals (CRS);

channel-state information reference signals (CSI-RS);

reference signals for enhanced physical broadcast channel (EPBCH);

or

channel user pilot signals (CUPS)/channel user beacon signals (CUBS).

22. The method of claim 12, wherein a duration of the unlicensed band cyclic prefix is less than or equal to a normal cyclic prefix associated with communications over licensed spectrum.

23. An apparatus configured for wireless communication, comprising:

at least one processor; and

a memory coupled to the at least one processor,

wherein the at least one processor is configured;

to generate, at a base station configured to transmit orthogonal frequency divisional multiple access (OFDMA) communication signals over at least an unlicensed spectrum, at least one of;

one or more synchronization signals, or a system broadcast signal for transmission;

to determine, by the base station, a non-clear channel assessment (non-CCA) subframe for transmission of the at least one of;

the one or more synchronization signals, or the system broadcast signal; and

to transmit, by the base station, the at least one of;

the one or more synchronization signals, or the system broadcast signal in the non-CCA subframe.

24. The apparatus of claim 23, wherein the at least one processor is further configured:

to detect, by the base station, a clear CCA in a CCA subframe; and

to transmit, by the base station, at least one other of;

the one or more synchronization signals, or one other system broadcast signal in the CCA subframe in response to detecting the clear CCA.

25. The apparatus of claim 23, wherein the non-CCA subframe in which the at least one of:

the one or more synchronization signals, or one or more system broadcast signals is transmitted is staggered over different carriers.

26. The apparatus of claim 23, wherein the base station includes at least one licensed carrier, and is in communication with at least one user equipment configured with one of:

a supplemental downlink (SDL), or carrier aggregation (CA) operation using a carrier in the unlicensed spectrum.

27. An apparatus configured for wireless communication, comprising:

at least one processor; and

a memory coupled to the at least one processor,

wherein the at least one processor is configured;

to receive, at a user equipment configured to receive orthogonal frequency divisional multiple access (OFDMA) communication signals over at least an unlicensed spectrum, at least one of;

one or more synchronization signals, or a system broadcast signal in a non-clear channel assessment (non-CCA) subframe from a base station; and

to communicate, by the user equipment, with the base station based on the received at least one of;

one or more synchronization signals, or a system broadcast signal.

28. The apparatus of claim 27, wherein the at least one processor is further configured:

to detect, by the user equipment, a clear CCA in a CCA subframe; and

to receive, by the user equipment, at least one other of;

the one or more synchronization signals, or one other system broadcast signal in the CCA subframe in response to detecting the clear CCA.

29. The apparatus of claim 27, wherein the non-CCA subframe in which the at least one of:

the one or more synchronization signals, or one or more system broadcast signals, is received is staggered over different carriers.

30. The apparatus of claim 27, wherein the user equipment is in communication with the base station having at least one licensed carrier, wherein the user equipment is configured with one of:

a supplemental downlink (SDL) or carrier aggregation (CA) operation using a carrier in the unlicensed spectrum.