# US 2018/0027588 A1 · Channel hopping aware channel access and re-transmission

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- Number: US 2018/0027588 A1
- Document ID: US20180027588A1
- Status: Published application
- Kind: A1
- Application number: 15/450,644
- Filed: 2017-03-06
- Published: 2018-01-25
- Earliest claimed: 2016-07-19
- Assignees: Texas Instruments Incorporated
- Applicants: Texas Instruments Incorporated
- Inventors: KUMARAN VIJAYASANKAR; JYOTHSNA KUNDURU
- Web page: https://patentgrep.com/patent/US20180027588A1

## CPC

- H04W 74/0808: using carrier sensing, e.g. carrier sense multiple access [CSMA]
- H04B 1/713: using frequency hopping
- H04L 5/0012: {Hopping in multicarrier systems}
- H04L 5/0055: {Physical resource allocation for ACK/NACK (for physical mapping arrangements in ARQ protocols H04L1/1861)}
- H04W 4/80: Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication
- H04W 74/085: {collision avoidance}
- H04B 2001/7154: {with means for preventing interference}
- Y02D 30/70: in wireless communication networks
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04B: TRANSMISSION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

A method of channel access for a radio device in an asynchronous channel hopping wireless network. A backoff time is set from an Interference Avoidance Delay plus a random backoff time for transmissions from the radio device. For initial frame transmissions, an initial value for a number of backoffs (nb) and initial number of preamble detection backoffs (npdb) is set. After waiting for expiring of the initial backoff time and provided a current npdb_value <a predetermined maximum npdb value, a first CCA is performed on the radio device's receive (Rx) channel, and a value for npdb is incremented following a failure. A second CCA is performed on a target radio device's Rx channel, wherein a value for nb is incremented following a failure. Provided a not busy is determined in the second CCA the radio device transmits a frame on the target radio device's Rx channel.

## Claims

### Claim 1

A method of channel access for a first radio device in an asynchronous channel hopping wireless network having at least one target radio device, comprising:
setting a backoff time for frame transmissions from said first radio device comprising an Interference Avoidance Delay (IAD) plus a random backoff time, wherein for an initial one of said frame transmissions also setting an initial value for a number of backoffs (nb) and an initial number for a number of preamble detection backoffs (npdb);
after waiting for an expiring of said backoff time and provided a current value for said npdb <a predetermined maximum npdb value, performing a first clear channel assessment (CCA) on said first radio device's receive (Rx) channel, wherein a value for said npdb is incremented following a failure of said first CCA;
performing a second CCA on said target radio device's Rx channel, wherein a value for said nb is incremented following a failure of said second CCA, and
provided a not busy is determined in said second CCA, said first radio device transmitting a frame on said target radio device's Rx channel.

### Claim 2 (depends on 1)

The method of claim 1, wherein said first radio device includes a processor having an associated memory, and wherein said first radio device has a channel hopping aware channel access and retransmission algorithm that provides said method which is implemented in hardware including digital logic or is implemented by code in said memory run by said processor.

### Claim 3 (depends on 1)

The method of claim 1, wherein said transmitting said frame comprises a retransmission which is delayed by said backoff time using an updated value for said IAD that results in said retransmission being on a different one of said target radio device's Rx channels compared to said target radio device's Rx channel used for a most recent attempt of said transmitting said frame.

### Claim 4 (depends on 3)

The method of claim 3, wherein said transmitting said frame comprises said retransmission and wherein said setting comprises setting said IAD to ½ a target dwell time (TDT).

### Claim 5 (depends on 1)

The method of claim 1, wherein said failure of said first CCA is handled by setting an updated value for said IAD to a maximum preamble detection time and then returning to said setting said backoff time.

### Claim 6 (depends on 1)

The method of claim 1, wherein said failure of said second CCA is handled setting an updated value for said IAD equal to a maximum of an expected frame transmission time and a target dwell time (TDT) and then returning to said setting said backoff time.

### Claim 7 (depends on 1)

The method of claim 1, wherein if said second CCA is successful said first radio device moves to said transmitting said frame, further comprising waiting for an acknowledgement (ACK) from said target radio device and marking said frame for retransmission if said ACK is not received and a current number of retransmission attempts is less than a maximum number of retransmission attempts.

### Claim 8 (depends on 3)

The method of claim 3, wherein said transmitting said frame comprises said retransmission and wherein said setting comprises setting an updated value for said IAD equal to a value for a basebackoff time that is equal to a remaining target dwell time (TDT) multiplied by said nb.

### Claim 9 (depends on 8)

The method of claim 8, wherein said failure of said second CCA is handled by setting an updated value for said IAD to said value of said basebackoff time multiplied by said nb, and then returning to said setting said backoff time.

### Claim 10 (depends on 1)

The method of claim 1, wherein said target radio device comprises a plurality of said target radio devices.

### Claim 11

A wireless radio device, comprising:
a transceiver coupled to at least one antenna and a real-time clock;
a processor having an associated memory which stores code for implementing a channel hopping aware channel access and retransmission algorithm or hardware including digital logic for implementing said algorithm, said algorithm for:
setting a backoff time for frame transmissions from said radio device comprising an Interference Avoidance Delay (IAD) plus a random backoff time, wherein for an initial one of said frame transmissions also setting an initial number for a number of backoffs (nb) and an initial value for a number of preamble detection backoffs (npdb);
after waiting for an expiring of said backoff time and provided a current value for said npdb <a predetermined maximum npdb value, performing a first clear channel assessment (CCA) on said radio device's receive (Rx) channel, wherein a value for said npdb is incremented following a failure of said first CCA;
performing a second CCA on an Rx channel of a target radio device, wherein a value for said nb is incremented following a failure of said second CCA, and
provided a not busy is determined in said second CCA, a first radio device transmitting a frame on said Rx channel of said target radio device.

### Claim 12 (depends on 11)

The wireless radio device of claim 11, wherein said radio device has said hardware including said digital logic.

### Claim 13 (depends on 11)

The wireless radio device of claim 11, wherein said radio device has said code for implementing said algorithm.

### Claim 14 (depends on 11)

The wireless radio device of claim 11, wherein said transmitting said frame comprises a retransmission which is delayed by said backoff time using an updated value for said IAD that results in said retransmission being on a different one of said target radio device's Rx channels compared to said target radio device's Rx channel used for a most recent attempt of said transmitting said frame.

### Claim 15 (depends on 14)

The wireless radio device of claim 14, wherein said transmitting said frame comprises said retransmission and wherein said setting comprises setting said IAD to ½ a target dwell time (TDT).

### Claim 16 (depends on 11)

The wireless radio device of claim 11, wherein said failure of said first CCA is handled by setting an updated value for said IAD to a maximum preamble detection time and then returning to said setting said backoff time.

### Claim 17 (depends on 11)

The wireless radio device of claim 11, wherein said failure of said second CCA is handled setting an updated value for said IAD equal to a maximum of an expected frame transmission time and a target dwell time (TDT) and then returning to said setting said backoff time.

### Claim 18 (depends on 11)

The wireless radio device of claim 11, wherein if said second CCA is successful, said first radio device moves to said transmitting said frame, further comprising waiting for an acknowledgement (ACK) from said target radio device and marking said frame for retransmission if said ACK is not received and a current number of retransmission attempts is less than a maximum number of retransmission attempts.

### Claim 19 (depends on 14)

The wireless radio device of claim 14, wherein said transmitting said frame comprises said retransmission and wherein said setting comprises setting an updated value for said IAD equal to a value for a basebackoff time that is equal to a remaining target dwell time (TDT) multiplied by said nb.

### Claim 20 (depends on 19)

The wireless radio device of claim 19, wherein said failure of said second CCA is handled by setting an updated value for said IAD to said value of said basebackoff time multiplied by said nb, and then returning to said setting said backoff time.