# US 2018/0324868 A1 · Narrow band physical random access channel frequency hopping patterns and detection schemes

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- Number: US 2018/0324868 A1
- Document ID: US20180324868A1
- Status: Published application
- Kind: A1
- Application number: 16/019,325
- Filed: 2018-06-26
- Published: 2018-11-08
- Earliest claimed: 2016-01-07
- Assignees: QUALCOMM Incorporated
- Applicants: QUALCOMM Incorporated
- Inventors: Peter Gaal; Renqiu Wang; Xiao Feng Wang; Hao Xu; Wanshi Chen
- Web page: https://patentgrep.com/patent/US20180324868A1

## CPC

- H04W 74/0833: Random access procedures, e.g. with 4-step access
- H04B 1/713: using frequency hopping
- H04B 1/7143: Arrangements for generation of hop patterns
- H04W 4/70: Services for machine-to-machine communication [M2M] or machine type communication [MTC]
- H04W 72/0453: Resources in frequency domain, e.g. a carrier in FDMA
- H04W 4/06: Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04B: TRANSMISSION

## Abstract

Methods, systems, and devices are described for wireless communication. Dedicated frequency resources of a physical random access channel (PRACH) may be designated for large and small frequency hops to facilitate the determination of timing offsets for PRACH transmissions. For instance, a frequency hopping pattern within the PRACH channel having a plurality of single tone transmission may include a first number of hops associated with a first frequency hopping distance (e.g., large frequency hops), and a second number of hops associated with a second frequency hopping distance (e.g., small frequency hops).

## Claims

### Claim 1

A method for wireless communication, comprising:
identifying a physical random access channel (PRACH) for communication between a base station and a user equipment (UE), the PRACH comprising a plurality of subcarriers; and
determining a frequency hopping pattern within the PRACH for a random access preamble comprising a plurality of single tone transmissions, the frequency hopping pattern comprising a plurality of frequency hops across the plurality of subcarriers, at least one frequency hop of the plurality of frequency hops being associated with a pseudo-random frequency hop distance.

### Claim 2 (depends on 1)

The method of claim 1, wherein the pseudo-random frequency hop distance is determined based on at least one of a pseudo-random linear hash function, or a pseudo-random linear cyclic shift.

### Claim 3 (depends on 1)

The method of claim 1, wherein the pseudo-random frequency hop distance is based on a number of subcarriers of the PRACH.

### Claim 4 (depends on 1)

The method of claim 1, further comprising:
detecting, by a base station, the random access preamble based at least in part on the determined frequency hopping pattern.

### Claim 5 (depends on 4)

The method of claim 4, further comprising:
determining a timing offset for uplink transmissions from the UE based at least in part on phase information in a plurality of tones of the detected random access preamble.

### Claim 6 (depends on 5)

The method of claim 5, wherein detecting the random access preamble comprises:
mapping the phase information for the plurality of tones to a sequence based at least in part on respective preamble tone intervals and respective subcarriers of the plurality of single tone transmissions; and
performing a frequency transform on the mapped sequence.

### Claim 7 (depends on 6)

The method of claim 6, wherein obtaining the timing offset comprises:
identifying a location of a maximum value of an output of the frequency transform of the mapped sequence.

### Claim 8 (depends on 7)

The method of claim 7, wherein detecting the random access preamble comprises:
comparing the maximum value with a threshold.

### Claim 9 (depends on 5)

The method of claim 5, wherein detecting the random access preamble comprises:
mapping differential phase information between two or more tones of the plurality of tones to a sequence based at least in part on the respective preamble tone intervals and respective subcarriers of the plurality of single tone transmissions; and
performing a frequency transform on the mapped sequence.

### Claim 10 (depends on 1)

The method of claim 1, further comprising:
transmitting, by the UE, the random access preamble according to the determined frequency hopping pattern.

### Claim 11

An apparatus for wireless communication, comprising:
means for identifying a physical random access channel (PRACH) for communication between a base station and a user equipment (UE), the PRACH comprising a plurality of subcarriers; and
means for determining a frequency hopping pattern within the PRACH for a random access preamble comprising a plurality of single tone transmissions, the frequency hopping pattern comprising a plurality of frequency hops across the plurality of subcarriers, at least one frequency hop of the plurality of frequency hops being associated with a pseudo-random frequency hop distance.

### Claim 12 (depends on 11)

The apparatus of claim 11, wherein the pseudo-random frequency hop distance is determined based on at least one of a pseudo-random linear hash function, or a pseudo-random linear cyclic shift.

### Claim 13 (depends on 11)

The apparatus of claim 11, wherein the pseudo-random frequency hop distance is based on a number of subcarriers of the PRACH.

### Claim 14 (depends on 11)

The apparatus of claim 11, further comprising:
means for detecting, by a base station, the random access preamble based at least in part on the determined frequency hopping pattern.

### Claim 15 (depends on 14)

The apparatus of claim 14, further comprising:
means for determining a timing offset for uplink transmissions from the UE based at least in part on phase information in a plurality of tones of the detected random access preamble.

### Claim 16 (depends on 15)

The apparatus of claim 15, wherein the means for detecting the random access preamble comprises:
means for mapping the phase information for the plurality of tones to a sequence based at least in part on respective preamble tone intervals and respective subcarriers of the plurality of single tone transmissions; and
means for performing a frequency transform on the mapped sequence.

### Claim 17 (depends on 16)

The apparatus of claim 16, wherein the means for obtaining the timing offset comprises:
means for identifying a location of a maximum value of an output of the frequency transform of the mapped sequence.

### Claim 18 (depends on 17)

The apparatus of claim 17, wherein the means for detecting the random access preamble comprises:
means for comparing the maximum value with a threshold.

### Claim 19 (depends on 15)

The apparatus of claim 15, wherein the means for detecting the random access preamble comprises:
means for mapping differential phase information between two or more tones of the plurality of tones to a sequence based at least in part on the respective preamble tone intervals and respective subcarriers of the plurality of single tone transmissions; and
means for performing a frequency transform on the mapped sequence.

### Claim 20 (depends on 11)

The apparatus of claim 11, further comprising:
means for transmitting, by the UE, the random access preamble according to the determined frequency hopping pattern.

### Claim 21

An apparatus for wireless communication, in a system comprising:
a processor;
memory in electronic communication with the processor; and
instructions stored in the memory and operable, when executed by the processor, to cause the apparatus to:
identify a physical random access channel (PRACH) for communication between a base station and a user equipment (UE), the PRACH comprising a plurality of subcarriers; and
determine a frequency hopping pattern within the PRACH for a random access preamble comprising a plurality of single tone transmissions, the frequency hopping pattern comprising a plurality of frequency hops across the plurality of subcarriers, at least one frequency hop of the plurality of frequency hops being associated with a pseudo-random frequency hop distance.

### Claim 22 (depends on 21)

The apparatus of claim 21, wherein the pseudo-random frequency hop distance is determined based on at least one of a pseudo-random linear hash function, or a pseudo-random linear cyclic shift.

### Claim 23 (depends on 21)

The apparatus of claim 21, wherein the pseudo-random frequency hop distance is based on a number of subcarriers of the PRACH.

### Claim 24 (depends on 21)

The apparatus of claim 21, wherein the instructions are further executable by the processor to:
detect, by a base station, the random access preamble based at least in part on the determined frequency hopping pattern.

### Claim 25 (depends on 24)

The apparatus of claim 24, wherein the instructions are further executable by the processor to:
determine a timing offset for uplink transmissions from the UE based at least in part on phase information in a plurality of tones of the detected random access preamble.

### Claim 26 (depends on 25)

The apparatus of claim 25, wherein the instructions are further executable by the processor to:
map the phase information for the plurality of tones to a sequence based at least in part on respective preamble tone intervals and respective subcarriers of the plurality of single tone transmissions; and
perform a frequency transform on the mapped sequence.

### Claim 27 (depends on 26)

The apparatus of claim 26, wherein the instructions are further executable by the processor to:
identify a location of a maximum value of an output of the frequency transform of the mapped sequence.

### Claim 28 (depends on 27)

The apparatus of claim 27, wherein the instructions are further executable by the processor to:
compare the maximum value with a threshold.

### Claim 29 (depends on 25)

The apparatus of claim 25, wherein the instructions are further executable by the processor to:
map differential phase information between two or more tones of the plurality of tones to a sequence based at least in part on respective preamble tone intervals and respective subcarriers of the plurality of single tone transmissions; and
perform a frequency transform on the mapped sequence.

### Claim 30 (depends on 21)

The apparatus of claim 21, wherein the instructions are further executable by the processor to:
transmit, by the UE, the random access preamble according to the determined frequency hopping pattern.

### Claim 31

A non-transitory computer readable medium storing code for wireless communication, the code comprising instructions executable by a processor to:
identify a physical random access channel (PRACH) for communication between a base station and a user equipment (UE), the PRACH comprising a plurality of subcarriers; and
determine a frequency hopping pattern within the PRACH for a random access preamble comprising a plurality of single tone transmissions, the frequency hopping pattern comprising a plurality of frequency hops across the plurality of subcarriers, at least one frequency hop of the plurality of frequency hops being associated with a pseudo-random frequency hop distance.