Connected Mode Discontinuous Reception for Narrow Band Internet of Things

• US 20170318620A1
• Filed: 04/27/2017
• Published: 11/02/2017
• Est. Priority Date: 04/28/2016
• Status: Abandoned Application

• Current Assignee: HFI Innovation, Inc. (MediaTek, Inc.)
• Original Assignee: MediaTek, Inc.
• Inventors: Tseng, Li-Chuan, Johansson, Per Johan Mikael
• Application Number:
  US15/498,763
• Publication Number:
  US 20170318620A1
• Time in Patent Office: Days
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04W 4/70 Services for machine-to-machine communication [M2M] or machine type communication [MTC]
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• 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 76/28 Discontinuous transmission [DTX]; Discontinuous reception [DRX]
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A novel and efficient DRX operation mechanism is proposed to maintain the reliability and energy efficiency for NB-IOT systems. In NB-IOT systems, the length of a NB-PDCCH (with repetition) and the interval between two NB-PDCCHs are extended and can be reconfigured by eNB for each UE. The eNB can also adaptively adjusts the DRX parameters accordingly. NB-IOT UE monitors the NB-PDCCH in DRX ON duration, which is configured in number of NB-PDCCHs. Specifically, if a DRX timer duration is configured by the eNB in units of a PDCCH period, the UE should calculate the timer in terms of number of PDCCH user-specific search spaces (USSs), or in terms of PDCCH subframes by multiplying the number of PDCCH periods with the PDCCH repetition level.

Claims

1. A method comprising:

receiving a control signal by a user equipment (UE) for configuring a number of narrowband physical downlink control channel (NB-PDCCH) periods that carry downlink control information (DCI), wherein each NB-PDCCH period refers to an interval between the start of two consecutive NB-PDCCH occasions;

configuring discontinuous reception (DRX) parameters by the UE for DRX operation in radio resource control (RRC) connected mode;

determining a NB-PDCCH user-specific search space (USS) for each NB-PDCCH period, wherein each NB-PDCCH USS comprises a repetition level of NB-PDCCH subframes for NB-PDCCH transmission; and

monitoring the DCI for a monitoring time such that the UE monitors a total number of NB-PDCCH USSs during an On Duration of each DRX cycle.

2. The method of claim 1, wherein the total number of NB-PDCCH subframes equals to the number of configured PDCCH periods multiplied by the repetition level.

3. The method of claim 1, wherein the monitoring time equals to the number of configured PDCCH periods multiplied by a time duration for each PDCCH period.

4. The method of claim 3, wherein the UE extends the monitoring time when some subframes within a NB-PDCCH USS are reserved for non-PDCCH transmission.

5. The method of claim 3, wherein the UE extends the monitoring time when a NB-PDCCH USS is located at the end of a hyper frame.

6. The method of claim 1, wherein the UE enters light sleep between two consecutive NB-PDCCHs when no grant is received in the former PDCCH.

7. The method of claim 1, wherein the UE periodically monitors the NB-PDCCHs by calculating wakeup time in each DRX cycle using a modulo formula.

8. The method of claim 7, wherein the UE enters idle mode when the total number of NB-PDCCH subframes are monitored and no grant is received.

9. The method of claim 1, wherein the UE monitors the NB-PDCCHs after each media access control (MAC) protocol data unit (PDU) transmission or retransmission.

10. The method of claim 1, wherein the UE monitors the NB-PDCCHs for retransmission in a hybrid automatic retransmission (HARQ) process.

11. A user equipment (UE) comprising:

a receiver that receives a control signal for configuring a number of narrowband physical downlink control channel (NB-PDCCH) periods that carry downlink control information (DCI), wherein each NB-PDCCH period refers to an interval between the start of two consecutive NB-PDCCH occasions;

a configuration circuit that configures discontinuous reception (DRX) parameters by the UE for DRX operation in radio resource control (RRC) connected mode; and

a monitoring circuit that determines a NB-PDCCH user-specific search space (USS) for each NB-PDCCH period, wherein each NB-PDCCH USS comprises a repetition number of NB-PDCCH subframes for NB-PDCCH transmission, and wherein the UE monitors the DCI for a monitoring time such that the UE monitors a total number of NB-PDCCH USSs during an On Duration of each DRX cycle.

12. The UE of claim 11, wherein the total number of NB-PDCCH subframes equals to the number of configured PDCCH periods multiplied by the repetition number.

13. The UE of claim 11, wherein the monitoring time equals to the number of configured PDCCH periods multiplied by a time duration for each PDCCH period.

14. The UE of claim 13, wherein the UE extends the monitoring time when some subframes within a NB-PDCCH USS are reserved for non-PDCCH transmission.

15. The UE of claim 13, wherein the UE extends the monitoring time when a NB-PDCCH USS is located at the end of a hyper frame.

16. The UE of claim 11, wherein the UE enters light sleep between two consecutive NB-PDCCHs when no grant is received in the former PDCCH.

17. The UE of claim 11, wherein the UE periodically monitors the NB-PDCCHs by calculating wakeup time in each DRX cycle using a modulo formula.

18. The UE of claim 17, wherein the UE enters idle mode when the total number of NB-PDCCH subframes are monitored and no grant is received.

19. The UE of claim 11, wherein the UE monitors the NB-PDCCHs after each media access control (MAC) protocol data unit (PDU) transmission or retransmission.

20. The UE of claim 11, wherein the UE monitors the NB-PDCCHs for retransmission in a hybrid automatic retransmission (HARQ) process.