Narrowband LTE cell search

Patent metadata

Field	Value
Publication number	US-11601901-B2
Application number	US-202017079672-A
Country	US
Kind code	B2
Filing date	Oct 26, 2020
Priority date	Jul 27, 2015
Publication date	Mar 7, 2023
Grant date	Mar 7, 2023

Abstract

Systems and methods relating to a narrowband Primary Synchronization Signal (NB-PSS) and a narrowband Secondary Synchronization Signal (NB-SSS) are disclosed. In some embodiments, a base station in a wireless network comprises a processor and storage that stores instructions executable by the processor whereby the base station is operable to transmit a NB-PSS and a NB-SSS in a narrowband portion of a downlink system bandwidth. The NB-PSS and the NB-SSS are transmitted such that more than two occurrences of the NB-PSS and more than two occurrences of the NB-SSS are transmitted over a defined time interval, each occurrence of the NB-PSS is transmitted over multiple contiguous Orthogonal Frequency Division Multiplexing (OFDM) symbols and each occurrence of the NB-SSS is transmitted over multiple contiguous OFDM symbols, and each occurrence of the NB-SSS provides an indication of a location of the occurrence of the NB-SSS within the defined time interval.

First claim

What is claimed is:

1. A base station in a wireless network, comprising:
a processor; and
storage that stores instructions executable by the processor whereby the base station is operable to:
transmit a narrowband Primary Synchronization Signal, NB-PSS, and a narrowband Secondary Synchronization Signal, NB-SSS, in a narrowband portion of a downlink system bandwidth, wherein:
multiple occurrences of the NB-PSS and multiple occurrences of the NB-SSS are transmitted over a defined time interval;
each occurrence of the NB-PSS is transmitted over multiple contiguous Orthogonal Frequency Division Multiplexing, OFDM, symbols and each occurrence of the NB-SSS is transmitted over multiple contiguous OFDM symbols; and
for each occurrence of the NB-SSS, a NB-SSS sequence for the occurrence is a function of only one particular location out of four possible locations of the occurrence of the NB-SSS within the defined time interval.

2. The base station of claim 1 wherein the narrowband portion of the downlink system bandwidth consists of 12 OFDM subcarriers.

3. The base station of claim 1 wherein the narrowband portion of the downlink system bandwidth has a bandwidth of 200 kilohertz, kHz.

4. The base station of claim 1 wherein the narrowband portion of the downlink system bandwidth has a bandwidth of 180 kilohertz, kHz.

5. The base station of claim 1 wherein the downlink system bandwidth is greater than or equal to 1.4 megahertz, MHz.

6. The base station of claim 1 wherein a NB-PSS sequence for the NB-PSS is a differentially encoded Zadoff-Chu sequence.

7. The base station of claim 1 wherein the NB-PSS provides an indication of a cell identity within a cell identity group for a respective cell.

8. The base station of claim 1 wherein the NB-SSS provides an indication of a cell identity group for a respective cell.

9. The base station of claim 1 wherein four occurrences of the NB-SSS are transmitted over a defined time interval subsequent to the defined time interval, wherein each of the four occurrences transmitted over the subsequent time interval provides an indication of one of four possible positions, within the subsequent time interval, of that occurrence of the NB-SSS.

10. A method of operation of a base station in a wireless network, comprising:
transmitting a narrowband Primary Synchronization Signal, NB-PSS, and a narrowband Secondary Synchronization Signal, NB-SSS, in a narrowband portion of a downlink system bandwidth, wherein:
multiple occurrences of the NB-PSS and multiple occurrences of the NB-SSS are transmitted over a defined time interval;
each occurrence of the NB-PSS is transmitted over multiple contiguous Orthogonal Frequency Division Multiplexing, OFDM, symbols and each occurrence of the NB-SSS is transmitted over multiple contiguous OFDM symbols; and
for each occurrence of the NB-SSS, a NB-SSS sequence for the occurrence is a function of only one particular location out of four possible locations of the occurrence of the NB-SSS within the defined time interval.

11. The method of claim 10 wherein the narrowband portion of the downlink system bandwidth consists of 12 OFDM subcarriers.

12. The method of claim 10 wherein the narrowband portion of the downlink system bandwidth has a bandwidth of 200 kilohertz, kHz.

13. The method of claim 10 wherein the narrowband portion of the downlink system bandwidth has a bandwidth of 180 kilohertz, kHz.

14. The method of claim 10 wherein the downlink system bandwidth is greater than or equal to 1.4 megahertz, MHz.

15. A wireless device in a wireless network, comprising:
a processor; and
storage that stores instructions executable by the processor whereby the wireless device is operable to:
perform a cell detection procedure based on a narrowband Primary Synchronization Signal, NB-PSS, and a narrowband Secondary Synchronization Signal, NB-SSS, received in a narrowband portion of a downlink system bandwidth, wherein:
multiple occurrences of the NB-PSS and multiple occurrences of the NB-SSS are transmitted over a defined time interval;
each occurrence of the NB-PSS is transmitted over multiple contiguous Orthogonal Frequency Division Multiplexing, OFDM, symbols and each occurrence of the NB-SSS is transmitted over multiple contiguous OFDM symbols; and
for each occurrence of the NB-SSS, a NB-SSS sequence for the occurrence is a function of only one particular location out of four possible locations of the occurrence of the NB-SSS within the defined time interval.

16. The wireless device of claim 15 wherein the narrowband portion of the downlink system bandwidth consists of 12 OFDM subcarriers.

17. The wireless device of claim 15 wherein the narrowband portion of the downlink system bandwidth has a bandwidth of 200 kilohertz, kHz.

18. The wireless device of claim 15 wherein the narrowband portion of the downlink system bandwidth has a bandwidth of 180 kilohertz, kHz.

19. The wireless device of claim 15 wherein the downlink system bandwidth is greater than or equal to 1.4 megahertz, MHz.

20. The wireless device of claim 15 wherein a NB-PSS sequence for the NB-PSS is a differentially encoded Zadoff-Chu sequence.

21. The wireless device of claim 15 wherein performing the cell detection procedure comprises:
detecting the NB-PSS; and
determining a cell identity within a cell identity group for a respective cell based on the detected NB-PSS.

22. The wireless device of claim 15 wherein performing the cell detection procedure comprises:
detecting the NB-SSS; and
determining a cell identity group for a respective cell and a frame timing for the respective cell based on the detected NB-SSS.

23. The wireless device of claim 15 wherein the defined time interval is a first defined time interval and the multiple occurrences of the NB-SSS are repeated in a second defined time interval subsequent to the first defined time interval at the same four possible positions as in the first defined time interval, and wherein each occurrence of the NB-SSS in the second defined time interval provides an indication of one of the four possible positions, within the second defined time interval, of that occurrence of the NB-SSS.

24. A method of operation of a wireless device in a wireless network, comprising:
performing a cell detection procedure based on a narrowband Primary Synchronization Signal, NB-PSS, and a narrowband Secondary Synchronization Signal, NB-SSS, received in a narrowband portion of a downlink system bandwidth, wherein:
multiple occurrences of the NB-PSS and multiple occurrences of the NB-SSS are transmitted over a defined time interval;
each occurrence of the NB-PSS is transmitted over multiple contiguous Orthogonal Frequency Division Multiplexing, OFDM, symbols and each occurrence of the NB-SSS is transmitted over multiple contiguous OFDM symbols; and
for each occurrence of the NB-SSS, a NB-SSS sequence for the occurrence is a function of only one particular location out of four possible locations of the occurrence of the NB-SSS within the defined time interval.

25. The base station of claim 1 wherein the NB-SSS sequence for the occurrence comprises two different Zadoff-Chu sequences.

26. The wireless device of claim 15 wherein the NB-SSS sequence for the occurrence comprises two different Zadoff-Chu sequences.

27. The base station of claim 1 wherein each of the four possible locations of the

Assignees

• Ericsson Telefon Ab L M

Inventors

• Lin Xingqin
• Adhikary Ansuman
• Johansson Niklas
• Wang Yi-Pin Eric

Classifications

• H04L5/001

  the frequencies being arranged in component carriers · CPC title

• H04W48/12

  using downlink control channel · CPC title

• H04W56/0015

  one node acting as a reference for the others · CPC title

• H04W56/001 Primary

  Synchronization between nodes · CPC title

• H04W4/70

  Services for machine-to-machine communication [M2M] or machine type communication [MTC] · CPC title