Common search space for machine type communications

• US 10,165,423 B2
• Filed: 06/06/2016
• Issued: 12/25/2018
• Est. Priority Date: 07/10/2015
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Rico Alvarino, Alberto, Chen, Wanshi, Xu, Hao
• Primary Examiner(s): Zhao, Wei
• Application Number:
  US15/174,678
• Publication Number:
  US 20170013391A1
• Time in Patent Office: 932 Days
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
• CPC Class Codes: H04W 4/70 Services for machine-to-machine communication [M2M] or machine type communication [MTC]
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• CPC Class Codes: H04W 68/005 Transmission of information for alerting of incoming communication
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access
• CPC Class Codes: H04W 76/28 Discontinuous transmission [DTX]; Discontinuous reception [DRX]

Abstract

Certain aspects of the present disclosure generally relate to wireless communications and more specifically to search space configuration in systems utilizing devices with limited communications resources, such as machine type communication (MTC) devices and enhanced MTC (eMTC) devices. An example method generally includes receiving a physical random access channel (PRACH) signal from a first user equipment (UE) on a first narrowband region within a wider system bandwidth and transmitting, in response to the PRACH signal, a random access response (RAR) signal in a first search space in a second narrowband region in at least a first subframe.

Claims

1. A method for wireless communications performed by a base station (BS), comprising:

receiving a physical random access channel (PRACH) signal from a first user equipment (UE) in a first narrowband region comprising one to six resource blocks (RBs) within a wider uplink (UL) system bandwidth; and

transmitting, in response to the PRACH signal, a random access response (RAR) message in a first search space, which is in a second narrowband region comprising one to six RBs within a wider downlink (DL) system bandwidth, in at least a first subframe.

2. The method of claim 1, further comprising:

transmitting a paging signal in a second search space in a third narrowband region comprising one to six RBs within the wider DL system bandwidth.

3. The method of claim 1, further comprising:

identifying a third search space in a fourth narrowband region comprising one to six RBs within the wider DL system bandwidth for transmitting RAR messages to a second UE with a different coverage enhancement (CE) level than the first UE;

transmitting information regarding the first search space and a first CE level for the first search space in a system information block (SIB); and

transmitting information regarding the third search space and a second CE level for the third search space in at least one of the SIB or another SIB.

4. The method of claim 1, further comprising:

transmitting information regarding the first search space in a system information block (SIB).

5. The method of claim 1, further comprising:

determining a RAR response window, a set of machine type communications (MTC) physical downlink control channel (MPDCCH) starting point subframes, a RAR offset number of subframes, and a bundle size for each of a plurality of coverage enhancement (CE) levels.

6. The method of claim 1, further comprising:

determining a radio frequency within the wider DL system bandwidth for paging, a time for paging, a bundle size for paging, and a set of monitoring candidates based at least on a maximum coverage enhancement (CE) level supported by the BS.

7. The method of claim 1, further comprising:

refraining from transmitting a dedicated channel to the first UE during at least a second subframe; and

transmitting at least one system information (SI) change or earthquake and tsunami warning system (ETWS) signal in a broadcast channel of the wider DL system bandwidth during at least the second subframe.

8. The method of claim 1, further comprising:

determining a set of repetitions for transmitting a downlink channel, based at least in part on a coverage enhancement (CE) level of the first UE;

determining a power boost value for the downlink channel;

transmitting an indication of the power boost value for the downlink channel; and

transmitting the downlink channel based on the set of repetitions and the power boost value.

9. The method of claim 8, further comprising determining at least one different power boost value for at least one repetition in the set of repetitions.

10. A method for wireless communications performed by a base station (BS), comprising:

scrambling a first demodulation reference signal (DM-RS) to a first UE with a first scrambling sequence initialized with a scrambling sequence initialization;

scrambling a second DM-RS to a second UE with a second scrambling sequence initialized with the scrambling sequence initialization; and

transmitting the scrambled first DM-RS to the first UE and the scrambled second DM-RS to the second UE in a same search space.

11. The method of claim 10, wherein the scrambling sequence initialization comprises a cell-specific scrambling sequence initialization.

12. A method for wireless communications performed by a user equipment (UE), comprising:

transmitting a physical random access channel (PRACH) signal to a base station (BS) in a first narrowband region comprising one to six resource blocks (RBs) within a wider uplink (UL) system bandwidth; and

receiving, in response to the PRACH signal, a random access response (RAR) message in a first search space, which is in a second narrowband region comprising one to six RBs within a wider downlink (DL) system bandwidth, in at least a first subframe.

13. The method of claim 12, further comprising:

receiving a paging signal in a second search space in a third narrowband region comprising one to six RBs within the wider DL system bandwidth.

14. The method of claim 13, further comprising:

determining a first set of repetitions for receiving a downlink channel, based at least in part on a maximum coverage enhancement (CE) level supported by the BS;

determining a received signal quality;

determining a second set of repetitions for receiving the downlink channel based at least in part on the first set of repetitions and the received signal quality; and

receiving the downlink channel based on the second set of repetitions.

15. The method of claim 14, further comprising:

receiving an indication of a power boost value for the downlink channel; and

determining the second set of repetitions for receiving the downlink channel further based on the indication of the power boost value.

16. The method of claim 15, wherein the indication of the power boost value for the downlink channel includes at least one different power boost value for at least one repetition in the first set of repetitions.

17. The method of claim 14, wherein the downlink channel is a control channel associated with a paging channel.

18. The method of claim 14, further comprising moving to a discontinuous reception mode (DRX) if the downlink channel is not received.

19. The method of claim 12, further comprising:

identifying a third search space in a fourth narrowband region comprising one to six RBs within the wider DL system bandwidth for receiving RAR messages based at least in part on a coverage enhancement (CE) level of the UE;

receiving information regarding the first search space and a first CE level for the first search space in a system information block (SIB); and

receiving information regarding the third search space and a second CE level for the third search space in at least one of the SIB or another SIB.

20. The method of claim 12, further comprising:

determining a RAR response window, a set of machine type communications (MTC) physical downlink control channel (MPDCCH) starting point subframes, a RAR offset number of subframes, and a bundle size for each of a plurality of coverage enhancement (CE) levels.

21. The method of claim 12, further comprising:

determining a radio frequency within the wider DL system bandwidth for paging, a time for paging, a bundle size for paging, and a set of monitoring candidates based at least on a maximum coverage enhancement (CE) level supported by the BS.

22. The method of claim 21, further comprising:

receiving information regarding the maximum CE level supported by the BS.

23. The method of claim 12, further comprising:

receiving at least one of a system information (SI) change or earthquake and tsunami warning system (ETWS) signal in the second narrowband region.

24. The method of claim 12, further comprising:

receiving at least one system information (SI) change or earthquake and tsunami warning system (ETWS) signal in a broadcast channel of the wider DL system bandwidth during at least a second subframe.

25. A method for wireless communications performed by a user equipment (UE), comprising:

receiving a first demodulation reference signal (DM-RS) scrambled with a first scrambling sequence initialized with a scrambling sequence initialization;

receiving a signal scrambled with the first scrambling sequence in a search space, wherein at least a second DM-RS scrambled with a second scrambling sequence initialized with the scrambling sequence initialization is transmitted in the search space; and

descrambling the signal with the first scrambling sequence.

26. The method of claim 25, wherein the scrambling sequence initialization comprises a cell-specific scrambling sequence initialization.