Physical Downlink Control Channel Design for Narrow Band Internet of Things

• US 20170181135A1
• Filed: 12/15/2016
• Published: 06/22/2017
• Est. Priority Date: 12/17/2015
• Status: Active Grant

• Current Assignee: MediaTek, Inc.
• Original Assignee: MediaTek, Inc.
• Inventors: Li, Xiu-Sheng, Chen, Po-Ying, Lin, Kuhn-Chang
• Granted Patent: US 10,104,651 B2
• Time in Patent Office: Days
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• 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: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority
• CPC Class Codes: H04L 5/0092 Indication of how the channel is divided
• CPC Class Codes: H04W 4/70 Services for machine-to-machine communication [M2M] or machine type communication [MTC]
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

Narrowband downlink control channel (NB-PDCCH) design for Narrowband Internet of Thing (IoT) devices is proposed. In one novel aspect, NB-PDCCH spans both first and second slots in the region of legacy physical downlink shared channel (PDSCH). A plurality of physical resource blocks (PRBs) is allocated for NB-PDCCH transmission that carry downlink control information (DCI). Furthermore, each NB-IoT device can be configured with n_PRB PRB pairs for NB-PDCCH transmission (e.g., n_PRB=1, 2, 4, or 8), and an NB-PDCCH transmission time interval (TTI) is composed by n_PRB subframes. An NB-PDCCH is encoded and occupies multiple narrowband control channel elements (NCCEs) based on aggregation level. In a preferred embodiment, each PRB pair for NB-PDCCH occupies two NCCEs.

Claims

1. A method comprising:

receiving a control signal by a user equipment (UE) to determine received physical resource blocks (PRBs) that carry downlink control information;

determining a set of candidate narrowband physical downlink control channels (NB-PDCCHs) within the PRBs, wherein each NB-PDCCH is associated with a set of narrowband control channel elements (NCCEs) for NB-PDCCH transmission;

collecting a plurality of resource elements (REs) for each NCCE, wherein each NCCE consists of a number of REs based on an NCCE to RE de-mapping rule; and

decoding the downlink control information that are mapped to the collected REs.

2. The method of claim 1, wherein one PRB is allocated for one NB-PDCCH having two NCCEs, wherein a first NCCE of the PRB is mapped to REs belonging to a first plurality of contiguous subcarriers of the PRB, and wherein a second NCCE of the PRB is mapped to REs belonging to a second plurality of contiguous subcarriers of the PRB.

3. The method of claim 1, wherein the collected REs for each NCCE are physically contiguous REs excluding REs allocated for NB-PDCCH demodulation reference signal transmission within a block of physically contiguous radio resources.

4. The method of claim 3, wherein the NB-PDCCH demodulation reference signal is a cell specific reference signal (CRS).

5. The method of claim 1, wherein the UE decodes the downlink control information in a single NCCE per NB-PDCCH transmission.

6. The method of claim 1, wherein the UE decodes the downlink control information in a plurality of NCCEs per NB-PDCCH transmission.

7. The method of claim 1, wherein the control signal defines a UE search space for the PRBs that carry the downlink control information.

8. A user equipment (UE) comprising:

a receiver that receives a control signal to determine received physical resource blocks (PRBs) that carry downlink control information in a cellular network;

a controller that determines a set of candidate narrowband physical downlink control channels (NB-PDCCHs) within the PRBs, wherein each NB-PDCCH is associated with a set of narrowband control channel elements (NCCEs) for NB-PDCCH transmission;

a collector that collects a plurality of resource elements (REs) for each NCCE, wherein each NCCE consists of a number of REs based on an NCCE to RE de-mapping rule; and

a decoder that decodes the downlink control information that are mapped to the collected REs.

9. The UE of claim 8, wherein one PRB is allocated for one NB-PDCCH having two NCCEs, wherein a first NCCE of the PRB is mapped to REs belonging to a first plurality of contiguous subcarriers of the PRB, and wherein a second NCCE of the PRB is mapped to REs belonging to a second plurality of contiguous subcarriers of the PRB.

10. The UE of claim 8, wherein the collected REs for each NCCE are physically contiguous REs excluding REs allocated for NB-PDCCH demodulation reference signal transmission within a block of physically contiguous radio resources.

11. The UE of claim 10, wherein the NB-PDCCH demodulation reference signal is a cell specific reference signal (CRS).

12. The UE of claim 8, wherein the UE decodes the downlink control information in a single NCCE per NB-PDCCH transmission.

13. The UE of claim 8, wherein the UE decodes the downlink control information in a plurality of NCCEs per NB-PDCCH transmission.

14. The UE of claim 8, wherein the control signal defines a UE search space for the PRBs that carry the downlink control information.

15. A method comprising:

transmitting a control signal from a communication device, wherein a set of physical resource blocks (PRBs) is allocated to carry downlink control information (DCI);

determining a set of candidate narrowband physical downlink control channels (NB-PDCCHs) within the PRBs, wherein each NB-PDCCH is associated with a set of narrowband control channel elements (NCCEs) to potentially carry the DCI;

mapping a plurality of resource elements (REs) to each NCCE based on an RE to NCCE mapping rule; and

encoding the DCI over the set of NCCEs to be transmitted to a UE if the DCI is intended for the UE.

16. The method of claim 15, wherein one PRB is allocated for one NB-PDCCH having two NCCEs, wherein a first NCCE of the PRB is mapped to REs belonging to a first plurality of contiguous subcarriers of the PRB, and wherein a second NCCE of the PRB is mapped to REs belonging to a second plurality of contiguous subcarriers of the PRB.

17. The method of claim 15, wherein the downlink control information is carried in a single NCCE per NB-PDCCH transmission.

18. The method of claim 15, wherein the downlink control information is carried in a plurality of NCCEs per NB-PDCCH transmission.

19. The method of claim 15, wherein the control signal defines a UE search space for the PRBs that carry the downlink control information.

20. The method of claim 19, wherein the UE search space is defined by an aggregation level of NCCEs per NB-PDCCH, a repetition number for NB-PDCCH transmission time interval (TTI) repetition, and a number of candidate NB-PDCCHs.