CN114599018A - Bluetooth Mesh network routing method based on automatic channel scheduling - Google Patents

Abstract

The invention discloses a Bluetooth Mesh network routing method based on automatic channel scheduling. The method comprises the following steps: all nodes firstly establish an empty neighbor table and an empty routing table, and then periodically send a broadcast packet with a destination address as a broadcast address; the node updates a neighbor table and a routing table according to the received broadcast packet, calculates the neighbor node and the monitoring channel of the node by using the MAC address, and monitors the corresponding channel after the initialization stage is finished; when the node has data packet transmission, searching whether the routing table has the routing table item of the destination node, if yes, transmitting the packet on the monitoring channel where the next hop is located, otherwise, transmitting the packet once on the monitoring channel where each neighbor is located. When the node receives the data packet, checking whether the destination address of the data packet is the node, if so, transmitting the data packet to an upper layer for processing, otherwise, checking whether the TTL value in the data packet is less than or equal to 1, if so, discarding the data packet, otherwise, entering a packet sending process.

Description

Bluetooth Mesh network routing method based on automatic channel scheduling

Technical Field

The invention relates to a Bluetooth Mesh network routing method based on automatic channel scheduling.

Background

With the increasing popularity of the internet of things (IoT), people put higher demands on lightweight and secure communication technologies, and although smart homes, smart offices and smart cities are developing increasingly, good interoperability among internet of things devices is still a challenge. People need to perform tasks such as various room lighting, sensing and temperature control by interconnecting hundreds of internet of things devices, but since most of the devices are resource-limited and are powered by button cells, wireless communication technologies such as Wi-Fi, which have high overhead and high power consumption, are not suitable for being used in the internet of things scene.

Bluetooth, and in particular Bluetooth Low Energy (BLE), has become one of the most common internet of things solutions in the last decade. BLE is designed to cope with the limitation of large resource overhead and power consumption, but initially only a star topology is considered, and a smartphone is used as a main central control entity, so that the topology is not suitable for covering a large-scale network such as an intelligent building. Many researchers and vendors have proposed academic or proprietary solutions to such problems, overcoming these limitations through multi-hop networks based on Bluetooth mesh, but there has been no official standard for Bluetooth mesh. Until 19/7/2017, the core specification of the official Bluetooth Mesh was proposed by the Bluetooth Special Interest Group (SIG), which provided a generally accepted standard for Bluetooth Mesh networks.

The protocol proposed by the core specification of Bluetooth Mesh uses the same underlying protocol stack as BLE, thus making Bluetooth Mesh backward compatible with Bluetooth 4.0. According to the specification, a Bluetooth Mesh network can support 32767 nodes, and can have a maximum 127-hop network. Except that the low-power-consumption nodes defined in the specification have the low-power-consumption characteristic, all other nodes need to be continuously powered, namely, the nodes continuously monitor the broadcast channel of the Bluetooth, all monitored data packets need to be forwarded or transmitted to an upper layer for further processing, and the nodes do not have the low-power-consumption characteristic. The nodes in the Bluetooth Mesh communicate with each other by using a Managed flooding (Managed flooding) mode, when a node in the network needs to send a data packet, the data packet is only broadcast once on the Bluetooth broadcast channels 37, 38 and 39 in sequence without any routing strategy, and all other nodes in the radio range of the node receive the data packet. And the nodes monitoring the data packet transmit to an upper layer for processing if the destination address in the packet is the address of the nodes per se, otherwise, whether the TTL field is less than or equal to 1 needs to be judged, if so, the data packet is directly discarded, and otherwise, the TTL field is reduced by one and then the data packet is continuously forwarded.

Because the Bluetooth Mesh defined by the core specification uses a managed flooding mode to perform mutual communication between nodes, when a plurality of nodes in the network need to send data packets, all relay nodes in the network participate in forwarding the data packets, so that a large number of repeated data packets exist in the network, and the probability of data packet collision on the Bluetooth broadcast channels 37, 38 and 39 is increased. Under the situation, the bluetooth broadcast channel resource waste is serious, the communication reliability is reduced, the end-to-end delay is invisibly increased due to retransmission caused by collision problems, and the collision problem of data packets is aggravated when the bluetooth broadcast channel is deployed in a large-scale dense network, so that the expandability is insufficient.

Disclosure of Invention

The invention provides a Bluetooth Mesh network routing method based on automatic channel scheduling, aiming at overcoming the defects in the prior art.

The invention aims to improve the defects of the existing Bluetooth Mesh protocol, and change the communication mode of the Bluetooth Mesh from the purposeful management routing into the purposeful routing based on the automatic channel scheduling strategy among nodes.

In order to realize the purpose, the technical scheme adopted by the invention is as follows: a Bluetooth Mesh network routing method based on automatic channel scheduling comprises the following steps:

(1) the network topology establishment initialization process comprises the following steps:

(1.1) all nodes in the network establish an empty neighbor table and an empty routing table;

(1.2) periodically sending broadcast packets with the destination address of the broadcast address by all nodes in the network, wherein the TTL field is set to be the maximum value 127;

(1.3) all nodes in the network judge whether a packet sending node is a neighbor node according to the TTL field of a received broadcast packet, and if so, the MAC address and the mesh address of the neighbor node are recorded in a neighbor table and a routing table;

(1.4) for a data packet sent by a non-neighbor node, calculating the hop count experienced by the data packet through a TTL field in the packet, recording the address of a previous hop node for forwarding the data packet when the hop count experienced by the data packet sent by the same node is the shortest hop count, taking the address of the next hop node as the address of a destination node as the address of a source node of the currently received data packet, and updating the address of the next hop node of the destination node address and hop count information in a routing table;

(1.5) neighbor nodes of nodes in the network monitor channel calculation: the node performs Hash operation on the MAC address of the neighbor item according to the neighbor table item in the neighbor table, and performs modulus operation on the Hash operation result to obtain a monitoring channel corresponding to each neighbor, and records the monitoring channel in the neighbor table;

(1.6) each node in the network monitors the channel calculation: the node calculates the channel to be monitored by the node according to the MAC address of the node through the same Hash operation as the step (1.5), and monitors the channel after the initialization stage is finished;

(2) a transmit data packet process comprising:

(2.1) when the node has the data packet to send, searching a routing table according to the mesh address of the destination node, if the mesh address of the destination node is in the routing table, searching a channel monitored by the node with the MAC address in a neighbor table according to the MAC address field of the next hop in the routing table, and sending the data packet on the channel, otherwise, executing the step (2.2);

(2.2) according to the monitored channel where the neighbor node is located recorded in the neighbor table, sending the data packet once on the monitored channel of each neighbor;

(3) a receive data packet process comprising:

(3.1) after receiving the data packet, the node in the network checks whether the destination address in the data packet is the mesh address of the node, if so, the node transmits the data packet to the upper layer of the protocol stack for processing, and if not, the node executes the step (3.2);

and (3.2) checking whether the TTL value in the data packet is less than or equal to 1, if so, directly discarding the data packet, and otherwise, executing the packet sending process in the step (2).

Furthermore, the destination address of the routing table in the invention is the Mesh address of the node defined according to the bluetooth Mesh specification.

In the step (1.4), the address of the previous hop node forwarding the data packet is the MAC address of the previous hop node.

In step (1.4), the hash operation is modulo by 40, i.e. the number of all channels used by BLE.

The invention has the beneficial effects that: by improving the managed flooding communication mode in the existing Bluetooth Mesh network and introducing a routing strategy, the channel resources of Bluetooth are fully utilized, most redundant data packets in the network are eliminated, the collision probability of the data packets in the network is reduced, and the utilization rate of the channel resources is improved; particularly, in a scene of intensive deployment of large-scale nodes, the network performance can be obviously improved, which is specifically embodied as follows: the packet receiving rate is improved, the end-to-end time delay is reduced, and the expansibility of the network is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

FIG. 1 is a work overview of a method embodying the present invention.

FIG. 2 is a detailed workflow diagram of the method of the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings. The method comprises the following specific steps:

(1) the network topology establishment initialization process comprises the following steps:

(1.1) all nodes in the network establish an empty neighbor table and an empty routing table, wherein the neighbor table comprises the following fields: the MAC address of the neighbor node, the monitoring channel of the neighbor node and a pointer pointing to the next table entry; the routing table contains fields including: mesh address of destination node, MAC address of next hop node, hop count needed to be experienced by data packet sent to destination node, pointer pointing to next table entry;

(1.2) periodically sending broadcast packets with the destination address of broadcast address (0 xffff) by all nodes in the network, wherein TTL field is set to maximum value 127;

(1.3) all nodes in the network judge whether a packet sending node is a neighbor node according to TTL fields in received broadcast packets; specifically, when the initial TTL value minus the in-packet TTL value is 1, the packet TTL value is a neighbor node, and then MAC addresses and mesh address information of the neighbor node are respectively recorded in a neighbor table and a routing table;

(1.4) for a data packet sent by a non-neighbor node, calculating the hop count of the data packet through a TTL field in the packet; specifically, subtracting a packet-internal TTL value from an initial TTL value, recording an MAC address of a previous hop node for forwarding a data packet when the hop count of the data packet is the shortest hop count, taking the MAC address as a next hop node with a destination node address being a source node address of the currently received data packet, and updating the next hop node address and hop count information of the destination node address in a routing table;

(1.5) neighbor nodes of the nodes in the network monitor channel calculation: the node performs hash operation of a 32-bit mixing function on the MAC address of the neighbor item according to the neighbor table item in the neighbor table, and performs modulus operation with divisor being BLE available channel number 40 on the hash operation result to obtain a monitoring channel corresponding to each neighbor and record the monitoring channel in the neighbor table;

(1.6) each node in the network monitors the channel calculation: the node calculates the channel to be monitored by the node according to the MAC address of the node through the same Hash operation as the step (1.5), and monitors the channel after the initialization stage is finished;

(2) a transmit data packet process comprising:

(2.1) when the node has the data packet to send, searching a routing table according to the mesh address of the destination node, if the mesh address of the destination node is in the routing table, searching a channel monitored by the node with the MAC address in a neighbor table according to the MAC address field of the next hop in the routing table, and sending the data packet on the channel, otherwise, executing the step (2.2);

(2.2) according to the monitored channel where the neighbor node is located recorded in the neighbor table, sending the data packet once on the monitored channel of each neighbor;

(3) a receive data packet process comprising:

(3.1) after receiving the data packet, the node in the network checks whether the destination address in the data packet is the mesh address of the node, if so, the node transfers the data packet to the upper layer of the protocol stack for processing, and if not, the node executes the step (3.2);

and (3.2) checking whether the TTL value in the data packet is less than or equal to 1, if so, directly discarding the data packet, and otherwise, executing the packet sending process in the step (2).

The embodiments described in this specification are merely illustrative of implementations of the inventive concept and the scope of the present invention should not be considered limited to the specific forms set forth in the embodiments but rather by the equivalents thereof as may occur to those skilled in the art upon consideration of the present inventive concept.

Claims (1)

1. A Bluetooth Mesh network routing method based on automatic channel scheduling is characterized by comprising the following steps:

(1) the initialization process for establishing the network topology comprises the following steps:

(1.1) all nodes in the network establish an empty neighbor table and an empty routing table, wherein the neighbor table comprises the following fields: the MAC address of the neighbor node, the monitoring channel of the neighbor node and a pointer pointing to the next table entry; the routing table contains fields including: mesh address of destination node, MAC address of next hop node, hop count needed to be experienced by data packet sent to destination node, pointer pointing to next table entry;

(1.2) periodically sending broadcast packets with the destination address of broadcast address (0 xffff) by all nodes in the network, wherein TTL field is set to maximum value 127;

(1.3) all nodes in the network judge whether a packet sending node is a neighbor node according to TTL fields in received broadcast packets; specifically, when the initial TTL value minus the in-packet TTL value is 1, the packet TTL value is a neighbor node, and then MAC addresses and mesh address information of the neighbor node are respectively recorded in a neighbor table and a routing table;

(1.4) for a data packet sent by a non-neighbor node, calculating the hop count of the data packet through a TTL field in the packet; specifically, subtracting a packet-internal TTL value from an initial TTL value, recording an MAC address of a previous hop node for forwarding a data packet when the hop count of the data packet is the shortest hop count, taking the MAC address as a next hop node with a destination node address being a source node address of the currently received data packet, and updating the next hop node address and hop count information of the destination node address in a routing table;

(1.5) neighbor nodes of nodes in the network monitor channel calculation: the node performs hash operation of a 32-bit mixing function on the MAC address of the neighbor item according to the neighbor table item in the neighbor table, and performs modulus operation with divisor being BLE available channel number 40 on the hash operation result to obtain a monitoring channel corresponding to each neighbor and record the monitoring channel in the neighbor table;

(1.6) each node in the network monitors the channel calculation: the node calculates the channel to be monitored by the node according to the MAC address of the node through the same Hash operation as the step (1.5), and monitors the channel after the initialization stage is finished;

(2) a transmit data packet process comprising:

(2.1) when the node has the data packet to send, searching a routing table according to the mesh address of the destination node, if the mesh address of the destination node is in the routing table, searching a channel monitored by the node with the MAC address in a neighbor table according to the MAC address field of the next hop in the routing table, and sending the data packet on the channel, otherwise, executing the step (2.2);

(2.2) according to the monitored channel where the neighbor node is located recorded in the neighbor table, sending the data packet once on the monitored channel of each neighbor;

(3) a receive data packet process comprising:

(3.1) after receiving the data packet, the node in the network checks whether the destination address in the data packet is the mesh address of the node, if so, the node transfers the data packet to the upper layer of the protocol stack for processing, and if not, the node executes the step (3.2);

and (3.2) checking whether the TTL value in the data packet is less than or equal to 1, if so, directly discarding the data packet, and otherwise, executing the packet sending process in the step (2).

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