Null tone transmission in an unlicensed or shared spectrum

Patent metadata

Field	Value
Publication number	US-2016286404-A1
Application number	US-201615080217-A
Country	US
Kind code	A1
Filing date	Mar 24, 2016
Priority date	Mar 26, 2015
Publication date	Sep 29, 2016
Grant date	—

Abstract

Systems, methods, and apparatuses for detecting interference caused by a wireless local area network (WLAN) and a wireless wide area network (WWAN) node operating in an unlicensed or shared spectrum is disclosed. In accordance with the present disclosure, a base station may generate a null tone pattern for one or more subframes transmitted to the UE. The null tone pattern may include one or more null tones mapped to consecutive symbols in each resource block to detect interference. Accordingly, a UE may monitor a wireless channel from a base station for a null tone transmission. The UE may detect a null tone pattern by decoding a known physical layer channel to identify the null tone pattern. In some aspects, the UE may generate channel estimates, decode allocated resources, determine timing of future transmissions and/or establish communication with the base station based on the identified null tone pattern.

First claim

What is claimed is:

1 . A method for wireless communications, comprising:
determining a null tone density for at least one subframe; generating a null tone pattern for the at least one subframe based on the null tone density; and transmitting the null tone pattern.

2 . The method of claim 1 , wherein the null tone pattern comprises a null tone in at least consecutive symbols in each resource block.

3 . The method of claim 1 , wherein transmitting the null tone pattern comprises transmitting the null tone pattern to at last one user equipment (UE).

4 . The method of claim 1 , wherein transmitting the null tone pattern comprises transmitting the null tone pattern over an unlicensed or shared spectrum.

5 . The method of claim 1 , wherein the UE is configured to detect, based on the null tone pattern, interference caused by a wireless local area network (WLAN) or a wireless wide area network (WWAN) operating in the unlicensed or shared spectrum.

6 . The method of claim 1 , wherein generating the null tone pattern for the at least one subframe comprises:
identifying a demodulation reference signal (DMRS) tone associated with the at least one subframe; and mapping the at least one null tone to avoid collision with the DMRS tone.

7 . The method of claim 1 , wherein generating the null tone pattern for the at least one subframe comprises:
identifying a cell specific reference signal (CRS) tone associated with the at least one subframe; and puncturing the null tone pattern by CRS.

8 . The method of claim 1 , wherein generating the null tone pattern for at least one subframe comprises modifying the null tone pattern for a resource block by applying a vertical shift to the null tone pattern.

9 . The method of claim 1 , wherein generating the null tone pattern for at least one subframe comprises:
identifying a synchronization signal associated with the at least one subframe, wherein the synchronization signal is at least one of primary synchronization signal (PSS) and secondary synchronization signal (SSS); and puncturing the null tone pattern by one of PSS and SSS.

10 . The method of claim 1 , wherein transmitting the null tone pattern to the at least one UE comprises:
identifying one or more subframes that include at least one null tone; and signaling to the UE the one or more identified subframes.

11 . The method of claim 1 , wherein transmitting the null tone pattern to the at least one UE comprises:
determining whether the null tone pattern is assigned to all resource blocks based on the null tone density; and scheduling a system information block (SIB) upon determining that the null tone pattern is not assigned to all resource blocks, wherein the scheduling comprises transmitting the SIB in the resource blocks in which there is no null tone transmission.

12 . The method of claim 1 , wherein determining the null tone density for the at least one subframe and generating the null tone pattern is in response to detecting interference from a wireless local area network (WLAN) signal on at least one orthogonal frequency-division multiplexing (OFDM) symbol associated with the at least one subframe.

13 . The method of claim 12 , further comprising:
activating the null tone pattern generation based on detecting the interference from the WLAN signal.

14 . The method of claim 1 , further comprising:
permitting at least one synchronization signal to puncture the null tone pattern.

15 . The method of claim 1 , further comprising:
rate matching at least one of enhanced physical downlink control channel (ePDCCH) or a physical downlink shared channel (PDSCH) around the null tone pattern.

16 . The method of claim 1 , further comprising:
configuring the null tone pattern to be same for one or more base stations associated with a public land mobile network.

17 . The method of claim 1 , further comprising:
puncturing at least one of enhanced physical downlink control channel (ePDCCH) or a physical downlink shared channel (PDSCH) in the at least one subframe.

18 . An apparatus for wireless communications, comprising:
means for determining a null tone density for at least one subframe; means for generating a null tone pattern for the at least one subframe based on the null tone density; and means for transmitting the null tone pattern.

19 . The apparatus of claim 18 , wherein the null tone pattern comprises a null tone in at least consecutive symbols in each resource block.

20 . The apparatus of claim 18 , wherein means for generating the null tone pattern for the at least one subframe comprises:
means for identifying a demodulation reference signal (DMRS) tone associated with the at least one subframe; and means for mapping the at least one null tone to avoid collision with the DMRS tone.

21 . The apparatus of claim 18 , wherein means for generating the null tone pattern for the at least one subframe comprises:
means for identifying a cell specific reference signal (CRS) tone associated with the at least one subframe; and means for puncturing the null tone pattern by CRS.

22 . The apparatus of claim 18 , wherein means for generating the null tone pattern for at least one subframe comprises means for modifying the null tone pattern for a resource block by applying a vertical shift to the null tone pattern.

23 . The apparatus of claim 18 , wherein means for generating the null tone pattern for at least one subframe comprises:
means for identifying a synchronization signal associated with the at least one subframe, wherein the synchronization signal is at least one of primary synchronization signal (PSS) and secondary synchronization signal (SSS); and means for puncturing the null tone pattern by one of PSS and SSS.

24 . A computer-readable medium storing code for wireless communications, the code comprising instructions executable to:
determine a null tone density for at least one subframe; generate a null tone pattern for the at least one subframe based on the null tone density; and transmit the null tone pattern.

25 . The computer-readable medium of claim 24 , wherein the null tone pattern comprises a null tone in at least consecutive symbols in each resource block.

26 . The computer-readable medium of claim 24 , wherein the instructions executable to generating the null tone pattern for the at least one subframe further comprises instructions executable to:
identify a demodulation reference signal (DMRS) tone associated with the at least one subframe; and map the at least one null tone to avoid collision with the DMRS tone.

27 . The computer-readable medium of claim 24 , wherein the instructions for generating the null tone pattern for the at least one subframe further comprises instructions executable to:
identify a cell specific reference signal (CRS) tone associated with the at least one subframe; and puncture the null tone pattern by CRS.

28 . The computer-readable medium of claim 24 , wherein the instructions for generating the null tone pattern for the at least one subframe further comprises instructions executable to modify the null tone pattern for a resource block by applying a vertical shift to the null tone pattern.

29 . An apparatus for wireless communications, comprising:
a processor; a memory coupled to the processor, the memory

Assignees

• Qualcomm Inc

Inventors

• Rico Alvarino Alberto
• Chendamarai Kannan Arumugam
• Zhang Xiaoxia
• Xu Hao
• Yerramalli Srinivas
• Luo Tao

Classifications

• H04L5/0051

  of dedicated pilots, i.e. pilots destined for a single user or terminal · CPC title

• H04L5/003 Primary

  Arrangements for allocating sub-channels of the transmission path · CPC title

• H04L27/0006

  Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio (for spectrum sharing between different networks H04W16/14) · CPC title

• H04L5/001 Primary

  the frequencies being arranged in component carriers · CPC title

• H04B17/345

  Interference values ({signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]} H04B17/336) · CPC title