US-12621747-B2 - Communication apparatus, communication method, and multi-hop relay system

Abstract

A communication apparatus in a multi-hop relay system in which a packet is transmitted and received using a flooding method in a first flooding slot and a second flooding slot each including a plurality of sub-slots, the communication apparatus performs: switching a frequency channel to be used to transmit and receive a packet between a first sub-slot and a second sub-slot in the first flooding slot; and not switching the frequency channel to be used to transmit and receive a packet within the second flooding slot, but switching the frequency channel to be used to transmit and receive a packet between a plurality of the second flooding slots.

Inventors

• Makoto Suzuki
• Sotaro Ohara

Assignees

• SONAS, INC.

Dates

Publication Date

20260505

Application Date

20231213

Priority Date

20210616

Claims (12)

1. 1 . A communication apparatus in a multi-hop relay system in which a packet is transmitted and received using a flooding method in a first flooding slot and a second flooding slot each including a plurality of sub-slots, the communication apparatus comprising: channel control unit configured to: switch a frequency channel to be used to transmit and receive a fixed- length packet, which is a synchronization packet, between a first sub-slot and a second sub-slot in the first flooding slot; and not switch the frequency channel to be used to transmit and receive a variable-length packet, which is a data packet, within the second flooding slot, but switching the frequency channel to be used to transmit and receive a variable-length packet between a plurality of the second flooding slots.
2. 2 . The communication apparatus according to claim 1 , wherein the channel control unit switches the frequency channel in accordance with a first hopping pattern for each sub-slot in the first flooding slot.
3. 3 . The communication apparatus according to claim 2 , wherein the first hopping pattern is determined based on a pseudo-random number that is synchronized between nodes.
4. 4 . The communication apparatus according to claim 1 , wherein the channel control unit switches the frequency channel to be used to transmit and receive a packet in accordance with a second hopping pattern for each of the plurality of second flooding slots.
5. 5 . The communication apparatus according to claim 4 , further comprising: identifying unit configured to identify the second hopping pattern based on a parameter of a packet received in the first flooding slot.
6. 6 . The communication apparatus according to claim 4 , wherein the second hopping pattern is determined based on a pseudo-random number that is synchronized between nodes.
7. 7 . The communication apparatus according to claim 1 , wherein a fixed-length packet is transmitted and received in the first flooding slot.
8. 8 . The communication apparatus according to claim 1 , further comprising: transmitting unit configured to transmit sensor data acquired from a sensor in a leading sub-slot of each of the second flooding slots.
9. 9 . The communication apparatus according to claim 1 , wherein the synchronization packet containing time stamp information is transmitted and received in the first flooding slot.
10. 10 . The communication apparatus according to claim 1 , wherein if a packet is received in the first sub-slot in the first flooding slot, the channel control unit identifies the frequency channel to be used to transmit and receive a packet in the second sub-slot, and the communication apparatus further comprises transfer unit configured to transfer, in the second sub-slot, the packet received in the first sub-slot.
11. 11 . A communication method for a multi-hop relay system in which a packet is transmitted and received between nodes using a flooding method in a first flooding slot and a second flooding slot each including a plurality of sub-slots, the communication method comprising: switching a frequency channel to be used to transmit and receive a fixed-length packet, which is a synchronization packet, between a first sub-slot and a second sub-slot in the first flooding slot; and not switching the frequency channel to be used to transmit and receive a variable-length packet, which is a data packet, within the second flooding slot, but switching the frequency channel to be used to transmit and receive a variable-length packet between a plurality of the second flooding slots.
12. 12 . A multi-hop relay system in which a packet is transmitted and received between nodes using a flooding method in a first flooding slot and a second flooding slot each including a plurality of sub-slots, the multi-hop relay system comprising a communication apparatus in a multi-hop relay system comprising: channel control unit configured to: switch a frequency channel to be used to transmit and receive a fixed- length packet, which is a synchronization packet, between a first sub-slot and a second sub-slot in the first flooding slot; and not switch the frequency channel to be used to transmit and receive a variable-length packet, which is a data packet, within the second flooding slot, but switching the frequency channel to be used to transmit and receive a variable-length packet between a plurality of the second flooding slots.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S) This application is a continuation of International Patent Application No. PCT/JP2022/023993 filed on Jun. 15, 2022, which claims priority to and the benefit of Japanese Patent Application No. 2021-100421 filed on Jun. 16, 2021, the entire disclosures of which are incorporated herein by reference. TECHNICAL FIELD The present invention relates to a communication apparatus that performs communication using a flooding method, a communication method, and a multi-hop relay system. BACKGROUND ART A broadcast method called flooding that uses concurrent transmission has been proposed in order to reduce power consumption of sensor nodes and increase the probability of data collection when a plurality of sensor nodes are distributed to collect data (Non-Patent Literature 1). In the flooding method using concurrent transmission, when one sensor node transmits data, one or more relay nodes that received the transmitted data transmit the same data in a broadcast manner immediately after receiving the data or after a fixed delay, thereby causing concurrent transmission of wireless signals (i.e. causing a plurality of relay nodes to transmit the same wireless signal concurrently or quasi-concurrently). By repeating this more than once, the data can be transmitted over the entire wireless communication system. In the flooding method using concurrent transmission, the same data is transmitted concurrently or quasi-concurrently. This enables the relay nodes to decode signals even if these relay nodes receive the signals from a plurality of nodes concurrently or quasi-concurrently. Furthermore, routing is not necessary either, which is advantageous as it is possible to simplify implementation and reduce power consumption. In a similar method, a time slot is allocated to each wireless communication node, which transmits data of this node using the flooding method within the time slot. A relay node that received the transmitted data relays the data in the time slot allocated thereto. In this method, the data transmitted from the transmission node is relayed such that the data ultimately reaches a data collection node by repeating the above process. (See Patent Literature 2) CITATION LIST Non-Patent Literature NPL1: F. Ferrari et al., “Efficient Network Flooding and Time Synchronization with Glossy”, IPSN'11, 2011NPL2: Chao GAO et al., “Efficient Collection Using Constructive-Interference Flooding in Wireless Sensor Networks”, The Institute of Electronics, Information and Communication Engineers Society Conference Proceedings, 2011_Communication (2), 428, 2011-08-30NPL3: Makoto Suzuki, Tomonori Nagayama, Sotaro Ohara, Hiroyuki Morikawa, “Structural Monitoring Using Concurrent Transmission Flooding,” The Institute of Electronics, Information and Communication Engineers Transactions B, No. 12, pp. 952-960, 2017 SUMMARY OF INVENTION Technical Problem In the field of wireless communications, channel hopping technology is known in which a frequency channel to be used for packet transmission is switched for the purpose of improving anti-interference performance. With the channel hopping technology, communication can continue even if a specific channel is occupied by another wireless system or the like, but the frequency channel to be used for packet transmission needs to be synchronized between the transmitting and receiving sides. The present invention has been made in view of the foregoing problem, and aims to provide a technology advantageous for performing efficient communication in a wireless communication system that performs communication by means of channel hopping using a flooding method. Solution to Problem One aspect of the present invention provides a communication apparatus in a multi-hop relay system in which a packet is transmitted and received using a flooding method in a first flooding slot and a second flooding slot each including a plurality of sub-slots, the communication apparatus comprising: channel control unit configured to: switch a frequency channel to be used to transmit and receive a packet between a first sub-slot and a second sub-slot in the first flooding slot; and not switch the frequency channel to be used to transmit and receive a packet within the second flooding slot, but switching the frequency channel to be used to transmit and receive a packet between a plurality of the second flooding slots. Another aspect of the present invention provides a communication method for a multi-hop relay system in which a packet is transmitted and received between nodes using a flooding method in a first flooding slot and a second flooding slot each including a plurality of sub-slots, the communication method comprising: switching a frequency channel to be used to transmit and receive a packet between a first sub-slot and a second sub-slot in the first flooding slot; and not switching the frequency channel to be used to transmit and receive a packet within the second floodin