Narrowband-physical random access channel techniques

• US 10,383,151 B2
• Filed: 12/23/2015
• Issued: 08/13/2019
• Est. Priority Date: 07/17/2015
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel IP Corporation (Intel Corporation)
• Inventors: Chatterjee, Depdeep, Xiong, Gang, Rashid, Mohammad Mamunur, Wu, Tao
• Primary Examiner(s): Acolatse, Kodzovi
• Application Number:
  US15/741,283
• Publication Number:
  US 20180206271A1
• Time in Patent Office: 1,329 Days
• Field of Search: None
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04W 72/044 based on the type of the allocated resource
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access

Abstract

Disclosed are narrowband (NB)-physical random access channel (PRACH) techniques for NB-long term evolution (LTE) systems supporting cellular internet of things (CloT) and machine-type communications (MTC) deployments. Apparatus and methods are described for generating, transmitting, or receiving an NB-PRACH defined by an NB-PRACH physical structure and an NB-PRACH numerology.

Claims

1. Electronic device circuitry for a user equipment (UE) configured to use a narrowband (NB) bandwidth when performing random access of a cellular network associated with an evolved Node B (eNB) providing the NB bandwidth at a frequency band of a repurposed deployment using global systems for mobile communications (GSM) spectrum, an in-band deployment using a physical resource block (PRB) of a larger-bandwidth long term evolution (LTE) system, or a guard-band deployment using a guard band of the larger-bandwidth LTE system, the electronic device circuitry comprising:

control circuitry configured to generate an NB-physical random access channel (NB-PRACH) defined by an NB-PRACH physical structure and an NB-PRACH numerology;

the NB-PRACH physical structure including a cyclic prefix (CP), a guard time (GT), and an NB-PRACH sequence between the CP and the GT; and

the NB-PRACH numerology configured to size components of the NB-PRACH physical structure such that a beginning of the CP and an end of the GT temporally correspond with a beginning and an end of one or more LTE subframes that each have a one millisecond (1 ms) duration, and the NB-PRACH numerology configured to maintain a number of subcarriers at a subcarrier spacing to establish the NB-PRACH as having an NB-PRACH bandwidth within the NB bandwidth,

wherein the control circuitry is further configured to randomly select one NB-PRACH preamble signature and a scheduling request (SR) transmission opportunity for transmission of the NB-PRACH and an SR within one LTE subframe.

2. The electronic device circuitry of claim 1, further comprising transmit circuitry coupled to the control circuitry, the transmit circuitry configured to transmit the NB-PRACH in the frequency band and within the NB-PRACH bandwidth of about 200 kHz or less.

3. The electronic device circuitry of claim 1, in which the NB-PRACH further includes coded bits that carry information related to the SR.

4. The electronic device circuitry of claim 3, in which control circuitry is further configured to generate, in a time dimension, the SR between the NB-PRACH sequence and the GT, or after the GT.

5. The electronic device circuitry of claim 1, in which a length of the CP is different from that of a CP used for transmission of an NB-physical uplink shared channel (NB-PUSCH) and/or an NB-physical uplink control channel (NB-PUCCH).

6. The electronic device circuitry of claim 1, in which a design of the NB-PRACH sequence is based on one or more Zadoff-Chu (ZC) sequences of prime-number length.

7. The electronic device circuitry of claim 1, in which the control circuitry is further configured to select a combination of an NB-PRACH preamble signature and a scheduling request (SR) transmission opportunity based on a single selection defining a one-to-one mapping between the NB-PRACH preamble signature and the SR transmission opportunity.

8. The electronic device circuitry of claim 1, in which the NB-PRACH bandwidth is 90 kHz.

9. The electronic device circuitry of claim 1, in which the NB-PRACH includes a scheduling request (SR), and the control circuitry is configured to multiplex the NB-PRACH with the SR by frequency division multiplexing (FDM) such that the SR is configured for simultaneous transmission in an NB-physical uplink shared channel (NB-PUSCH) and/or an NB-physical uplink control channel (NB-PUCCH).

10. The electronic device circuitry of claim 1, in which the subcarrier spacing for the LTE subframe carrying the NB-PRACH is set to a smaller value than 15 kHz and is equal to that of an NB-physical uplink control channel (NB-PUCCH) and/or an NB-physical uplink shared channel (NB-PUSCH).

11. The electronic device circuitry of claim 10, in which a subcarrier spacing for a legacy PUSCH is an integer multiple of the subcarrier spacing for one or both of the NB-PRACH and the NB-PUSCH.

12. A method performed by a user equipment (UE) configured to use a narrowband (NB) bandwidth when performing random access of a cellular network associated with an evolved Node B (eNB), the method comprising:

receiving from the eNB an indication of availability of the NB bandwidth at a frequency band of a repurposed deployment using global systems for mobile communications (GSM) spectrum, an in-band deployment using a physical resource block (PRB) of a larger-bandwidth long term evolution (LTE) system, or a guard-band deployment using a guard band of the larger-bandwidth LTE system; and

generating an NB-physical random access channel (NB-PRACH) defined by an NB-PRACH physical structure and an NB-PRACH numerology;

the NB-PRACH physical structure including a cyclic prefix (CP), a guard time (GT), and an NB-PRACH sequence between the CP and the GT;

the NB-PRACH numerology configured to size components of the NB-PRACH physical structure such that a beginning of the CP and an end of the GT temporally correspond with a beginning and an end of one or more LTE subframes that each have a one millisecond (1 ms) duration, and the NB-PRACH numerology configured to maintain a number of subcarriers at a subcarrier spacing to establish the NB-PRACH as having an NB-PRACH bandwidth within the NB bandwidth; and

selecting a combination of an NB-PRACH preamble signature and a scheduling request (SR) transmission opportunity based on a single selection defining a one-to-one mapping between the NB-PRACH preamble signature and the SR transmission opportunity.

13. The method of claim 12, in which the subcarrier spacing for the NB-PRACH is different from that used for other uplink (UL) transmissions for a larger-bandwidth LTE system physical uplink control channel (PUCCH), a larger-bandwidth LTE system physical uplink shared channel (PUSCH), and/or a larger-bandwidth LTE system PRACH.

14. The method of claim 12, in which the NB-PRACH includes guard bands at its edges, and in which a size of a guard band for the NB-PRACH is smaller than that of a larger-bandwidth LTE system PRACH.

15. The method of claim 12, in which the NB-PRACH sequence comprises multiple repetitions of an NB-PRACH preamble sequence.

16. The method of claim 15, further comprising applying a cover code to the NB-PRACH preamble sequence.

17. The method of claim 15, further comprising, in response to a failure to receive a random access response (RAR) from the eNB after NB-PRACH transmissions at a first NB-PRACH repetition level, transmitting at a second NB-PRACH repetition level that is different from the first NB-PRACH repetition level.

18. An apparatus of a user equipment (UE) for accessing a narrowband (NB)-long term evolution (LTE) network connection, the apparatus comprising:

control circuitry configured to generate an NB-physical random access channel (NB-PRACH) preamble and a scheduling request (SR), the NB-PRACH preamble being for transmission in an NB-PRACH and the SR being for transmission in a physical uplink (UL) channel having a frequency band that is different from that of the NB-PRACH, the NB-PRACH having a frequency bandwidth of up to 200 kilohertz (kHz) and a transmission time duration of one or more LTE transmission time intervals (TTIs); and

the control circuitry further configured to multiplex the NB-PRACH and SR by frequency division multiplexing (FDM) for simultaneous transmission during the transmission time duration and through, respectively, the NB-PRACH and the physical UL channel,

wherein a minimum distance between cyclic shifts (NCS) for the NB-PRACH sequence is reduced compared to those of larger-bandwidth LTE PRACH sequences.

19. The apparatus of claim 18, in which the control circuitry selects NB-PRACH resources based on repetition levels or coverage classes, the NB-PRACH resources being separated based on either time-division multiplexing (TDM) for transmission in one or multiple subframes, code-division multiplexing (CDM) having different NB-PRACH preambles reserved for each repetition level or coverage class, or frequency-division multiplexing (FDM) for transmission in one or more NB bandwidths.

20. The apparatus of claim 18, in which the UE is configured to receive NB-LTE system information blocks (NB-LTE SIBs) as part of an NB-PRACH configuration signaling, and the UE, in response to the NB-PRACH configuration signaling, is configured to transmit by using a power ramping mechanism to adjust NB-PRACH transmit power based on a selected number of repetitions of the NB-PRACH sequence.

21. The apparatus of claim 18, in which the minimum distance between cyclic shifts is given by an expression NCS≥

ceil((2*R/c+DS)*(NZC/TSEQ))+gs;

where R, c, DS, NZC, TSEQ, and gs are, respectively, the target cell radius, speed of light, target maximum delay spread, NB-PRACH sequence length, NB-PRACH sequence duration, and additional guard samples.

22. The apparatus of claim 18, in which the control circuitry is configured to establish an NB-PRACH configuration based on an NB-PRACH configuration index that is less than six bits in size and code-points of the NB-PRACH configuration index that indicate an NB-PRACH preamble format among multiple NB-PRACH preamble formats, and/or that indicate time resources available for NB-PRACH transmission.

23. The apparatus of claim 22, in which the time resources available for NB-PRACH transmission are based on an expression k*f*10 ms, where k and f are, respectively, an integer value greater than or equal to one, and a ratio of downlink (DL) to uplink (UL) subcarrier spacing.

24. Electronic device circuitry for a user equipment (UE) configured to use a narrowband (NB) bandwidth when performing random access of a cellular network associated with an evolved Node B (eNB) providing the NB bandwidth at a frequency band of a repurposed deployment using global systems for mobile communications (GSM) spectrum, an in-band deployment using a physical resource block (PRB) of a larger-bandwidth long term evolution (LTE) system, or a guard-band deployment using a guard band of the larger-bandwidth LTE system, the electronic device circuitry comprising:

control circuitry configured to generate an NB-physical random access channel (NB-PRACH) defined by an NB-PRACH physical structure and an NB-PRACH numerology;

the NB-PRACH physical structure including a cyclic prefix (CP), a guard time (GT), and an NB-PRACH sequence between the CP and the GT;

the NB-PRACH numerology configured to size components of the NB-PRACH physical structure such that a beginning of the CP and an end of the GT temporally correspond with a beginning and an end of one or more LTE subframes that each have a one millisecond (1 ms) duration, and the NB-PRACH numerology configured to maintain a number of subcarriers at a subcarrier spacing to establish the NB-PRACH as having an NB-PRACH bandwidth within the NB bandwidth; and

the NB-PRACH includes a scheduling request (SR), and the control circuitry is configured to multiplex the NB-PRACH with the SR by frequency division multiplexing (FDM) such that the SR is configured for simultaneous transmission in an NB-physical uplink shared channel (NB-PUSCH) and/or an NB-physical uplink control channel (NB-PUCCH).

25. An apparatus of a user equipment (UE) for accessing a narrowband (NB)-long term evolution (LTE) network connection, the apparatus comprising:

control circuitry configured to generate an NB-physical random access channel (NB-PRACH) preamble and a scheduling request (SR), the NB-PRACH preamble being for transmission in an NB-PRACH and the SR being for transmission in a physical uplink (UL) channel having a frequency band that is different from that of the NB-PRACH, the NB-PRACH having a frequency bandwidth of up to 200 kilohertz (kHz) and a transmission time duration of one or more LTE transmission time intervals (TTIs); and

the control circuitry further configured to multiplex the NB-PRACH and SR by frequency division multiplexing (FDM) for simultaneous transmission during the transmission time duration and through, respectively, the NB-PRACH and the physical UL channel,

wherein the control circuitry is further configured to establish an NB-PRACH configuration based on an NB-PRACH configuration index that is less than six bits in size and code-points of the NB-PRACH configuration index that indicate an NB-PRACH preamble format among multiple NB-PRACH preamble formats, and/or that indicate time resources available for NB-PRACH transmission.

26. The apparatus of claim 25, in which the time resources available for NB-PRACH transmission are based on an expression k*f*10 ms, where k and f are, respectively, an integer value greater than or equal to one, and a ratio of downlink (DL) to uplink (UL) subcarrier spacing.