# US 10,313,039 B2 · Fast synchronization scheduling apparatus and method for time slotted channel hopping in congested industrial wireless network environment

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- Number: US 10,313,039 B2
- Document ID: US10313039B2
- Status: Granted
- Kind: B2
- Application number: 16/177,958
- Filed: 2018-11-01
- Published: 2019-03-07
- Granted: 2019-06-04
- Earliest claimed: 2016-12-28
- Assignees: Pusan National University Industry-University Cooperation Foundation
- Applicants: Pusan National University Industry-University Cooperation Foundation
- Inventors: Sanghwa Chung; Jaeyoung Kim
- Web page: https://patentgrep.com/patent/US10313039B2

## CPC

- H04J 3/06: Synchronising arrangements {(for television systems H04N5/04; bit-synchronisation H04L7/00)}
- H04B 17/318: Received signal strength
- H04J 3/0694: {Synchronisation in a TDMA node, e.g. TTP}
- H04W 28/0284: {detecting congestion or overload during communication (monitoring arrangements H04L43/00)}
- H04W 28/06: Optimizing {the usage of the radio link}, e.g. header compression, information sizing {, discarding information (system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365)}
- H04W 56/001: {Synchronization between nodes}
- H04W 72/0446: Resources in time domain, e.g. slots or frames
- H04J 3/10: Arrangements for reducing cross-talk between channels
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)
- H04B: TRANSMISSION
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

The fast synchronization scheduling apparatus includes: a radio frequency (RF) transmission and reception module configured to transmit and receive RF signals from nearby channels, a received signal strength indicator (RSSI) reception and storage module configured to receive RSSI values from the RF signals received from the RF transmission and reception module and store the received RSSI values, a channel sorting module configured to measure Channel Quality Estimation (CQE) values of the respective channels by putting the RSSI values of the respective channels received from the RSSI reception and storage module into a CQE formula and to sort the channels in order of highest CQE value (highest channel quality) based on the measured CQE values.

## Claims

### Claim 1

A fast synchronization scheduling method for Time Slotted Channel Hopping (TSCH) in a congested industrial wireless network environment, the fast synchronization scheduling method comprising steps of:
(a) measuring, whether an RSSI value is found to exist in each of channels;
(b) in response to no RSSI value being found to exist among all the channels as a result of the measurement in the step (a), repeating the step (a);
(c) detecting RSSI values from two of all the channels when an RSSI value is found to exist in each of the channels as a result of the measurement;
(d) measuring, Channel Quality Estimation (CQE) values of the respective channels by putting the received RSSI values of the respective channels into a CQE formula, and sorting the channels in order of highest CQE value (a highest channel quality) based on the measured CQE values;
(e) searching for coordinators in a surrounding area using an advertisement packet (ADV) received from an ADV receiver, setting a number of the found coordinators and a good group, and delivering information about channels having high CQE values to a Personal Area Network (PAN) coordinator;
(f) generating, when a time slot for an ADV is allocated to each coordinator on the basis of the information delivered from the PAN coordinator and timeslot information is received by the coordinator, an ADV message and transmitting the generated ADV message in a designated channel during the time slot; and
(g) selecting, when an ADV is not received by the time a predetermined number of slotframes have passed, a channel having the highest CQE value again on the basis of CQE values collected by that time, and returning to step (c) and proceeding with the subsequent steps.

### Claim 2 (depends on 1)

The fast synchronization scheduling method of claim 1, wherein step (f) comprises:
calculating, a number of channels classified as being part of the good group on the basis of the CQE value, and calculating a number of coordinators,
wherein when the number of coordinators is one and when the number of channels is in a range of one to three, allocating a number of channels (ADV slots) corresponding to the number of channels, and delivering information about the allocation to the one coordinator,
wherein when the number of coordinators is two and when the number of channels is one, having the one channel (an ADV slot) be primarily allocated to a coordinator with a lower numbered coordinator ID, and delivering information about the allocation to the coordinator,
wherein when the number of coordinators is two and when the number of channels is two, having the two channels be respectively allocated to the two coordinators, and delivering information about the allocation to the two coordinators,
wherein when the number of coordinators is two and when the number of channels is three, having two of the three channels be allocated to a coordinator with a lower numbered coordinator ID, having the one remaining channel be allocated to the remaining coordinator, and delivering information about the allocation to the three coordinators,
wherein when the number of coordinators is three or more, comparing the number of coordinators with the number of channels in the good group,
wherein when the number of coordinators is three or more and when the number of the channels in the good group is smaller than the number of the coordinators as a result of the comparing, having the channels in the good group be allocated to the coordinators in order of lowest numbered coordinator ID, and delivering information about the allocation to the coordinators, and
wherein when the number of coordinators is three or more and when the number of the channels in the good group is larger than or equal to the number of the coordinators as the result of the comparing, having one channel be allocated to one coordinator such that ADV messages are simultaneously transmitted in a plurality of channels, and delivering information about the allocation to the coordinators.

### Claim 3 (depends on 2)

The fast synchronization scheduling method of claim 2, wherein when the number of coordinators is one and when the number of channels is four or more, further comprising allocating three channels that are ranked as the three channels with the highest qualities (highest CQE values) among the four channels to the coordinator, and delivering information about the allocation to the coordinator.

### Claim 4 (depends on 2)

The fast synchronization scheduling method of claim 2, wherein when the number of coordinators is two and when the number of channels is four or more, further comprising allocating three channels that are ranked as the three channels with the highest qualities (highest CQE values) among the four channels to the coordinators and not using the remaining channel.