CN110167115A - Wireless body area network MAC protocol, communication means and system based on wake-up mechanism - Google Patents

Abstract

The wireless body area network MAC protocol based on the wake-up mechanism, the data service in the wireless body area network is divided into three types: periodic service, on-demand service and random service, and the protocol builds a wake-up channel and a transmission channel between the coordinator and the node , the wake-up channel is used to transmit the wake-up signal, and the transmission channel is used to transmit data; and, in the periodic service and on-demand service, the coordinator sends a wake-up signal to the node through the wake-up channel to make the node enter the wake-up state; in the random service, the node passes the wake-up The channel sends a wake-up signal to the coordinator and enters the wake-up state; when different nodes have channel conflicts in transmitting data, they will first transmit random service data, and then transmit periodic service data and on-demand service data through the CSMA/CA competition mechanism. The invention provides a wake-up mechanism-based wireless body area network MAC protocol, a communication method and a system, which have lower network energy consumption and high reliability.

Description

Wireless body area network MAC protocol, communication method and system based on wake-up mechanism

technical field

The invention relates to the field of wireless body area network, in particular to a wake-up mechanism-based wireless body area network MAC protocol, a communication method and a system.

Background technique

With the development of our country's society and the improvement of people's living standards, people are paying more and more attention to health issues. However, the problem of population aging in today's society is becoming increasingly serious and has become a major challenge faced by all sectors of society. In addition, chronic diseases have also become a major public health problem that endangers the health of our people. Most of these diseases can be treated or prevented if they are detected early.

In this context, the wireless body area network technology with the main purpose of health monitoring came into being. Wireless body area network is a short-distance communication network composed of sensor nodes placed in different parts of the human body with different functions and mobile devices around the human body, which is used to monitor the physical condition of the human body or provide various wireless applications. In WBAN, the MAC protocol determines the wireless channel usage and resource allocation of nodes, which is closely related to the performance of WBAN. Therefore, it is of great significance to study the MAC protocol of WBAN to improve the performance of WBAN network.

Nowadays, the research hotspots on the MAC protocol of wireless body area network focus on several aspects: energy consumption, delay, energy efficiency, scalability, network efficiency, and algorithm complexity. At present, it is generally believed that the importance is decreasing in order, that is, how to effectively reduce energy consumption and reduce delay has become the primary consideration in the design of wireless body area network MAC protocols.

Figure 1 shows the power consumption comparison diagram of wireless communication. It can be seen from the figure that in the life cycle of the wireless body area network, the energy consumption of nodes mainly comes from the sending and receiving of radio frequency templates, and the energy consumption accounts for The least percentage is the sleep period of the node. Therefore, reducing energy consumption can be achieved by reducing sending and receiving energy consumption, avoiding idle listening, and increasing sleep time. Because the MAC protocol directly controls the radio frequency module of the node, the design of the MAC protocol in the wireless body area network has an important impact on the network energy consumption.

So far, researchers have proposed a large number of MAC protocols. On the one hand, they can reduce network energy consumption and improve network performance by reducing data traffic, reducing data conflicts, and adopting low duty cycle mechanisms.

A paper "Henna S, Sajeel M, Bashir F, et al. A fair contention access scheme for low-priority traffic in wireless body area networks [J]. Sensors, 2017, 17 (9): 1931-1951." A traffic-adaptive priority-based superframe structure that reduces contention in the CAP cycle and gives low-priority traffic a fair chance.

The document "Yang O, Heinzelman W. Modeling and Performance Analysis for Duty-Cycled MAC Protocols with Applications to S-MAC and X-MAC [J]. IEEE Transactions on Mobile Computing, 2012, 11(6): 905-921." The S-MAC adopts a low duty cycle mechanism, and the nodes will work and sleep periodically, which can reduce the energy consumption of the network due to idle listening, and adopt the method of avoiding crosstalk and message transmission, reducing crosstalk and Control overhead. This type of MAC protocol uses a duty-cycle mechanism, which saves node energy by putting the node to sleep. However, although the MAC protocol with periodic sleep can save energy and energy, it cannot process events in time during sleep, and may lose or delay urgent and important data that needs to be transmitted, resulting in serious consequences.

Another effective mechanism to reduce power consumption is to employ a wake-up scheme.

The document "Pande H, Kharat M U. Modified WiseMAC protocol for energy efficient wireless sensor networks with better throughput [C]. International Conference on Internet of Things & Applications. IEEE, 2016: 364-367." Wise-MAC proposed in front of each data frame A wake-up preamble of size equal to the sample period is transmitted to ensure that the receiver will be awake when the data portion of the packet arrives, this technique provides very low power consumption when the channel is idle.

The document "Ullah N, Khan P, Kwak K S.A very low power MAC (VLPM) protocol for wireless body area networks [J]. Sensors, 2011, 11 (4): 3717-3737." The VLPM proposed is based on the existing wake-up radio Methods The proposed low-power MAC protocol divides the traffic into uplink and downlink traffic, and the nodes are equipped with low-power wake-up transceivers to reduce energy consumption by increasing the sleep time of nodes. But this protocol is suitable for use in conditions with low traffic. For high traffic situations, optimization is required.

Contents of the invention

In order to solve the deficiencies in the prior art, the present invention provides a wake-up mechanism-based wireless body area network MAC protocol, a communication method and a system, which have lower network energy consumption and high reliability.

In order to achieve the above object, the specific solution adopted by the present invention is: a wireless body area network MAC protocol based on a wake-up mechanism. Data services in the wireless body area network are divided into three types: periodic services, on-demand services, and random services. The protocol A wake-up channel and a transmission channel are constructed between the coordinator and the node, the wake-up channel is used to transmit the wake-up signal, and the transmission channel is used to transmit data; and, in the periodic service and the on-demand service, the coordinator sends the wake-up signal to the node through the wake-up channel to Make the node enter the wake-up state; in the random business, the node sends a wake-up signal to the coordinator through the wake-up channel, and enters the wake-up state; when different nodes have channel conflicts in transmitting data, they will first transmit random business data, and then transmit through the CSMA/CA competition mechanism Periodic business data and on-demand business data.

A communication method of a wireless body area network MAC protocol based on a wake-up mechanism,

The communication process of the random business includes:

S11. The node sends a wake-up signal to the coordinator through the wake-up channel;

S12. The coordinator returns an ACK frame after receiving the wake-up signal, and then sends a beacon frame to the node;

S13. If the node does not receive the ACK frame or the beacon frame, resend the wake-up signal until the beacon frame is received;

S14. The node sends data to the coordinator through the transmission channel;

S15. The coordinator returns an ACK frame to the node after receiving the data;

S16. If the node receives the ACK frame, the communication process ends, and if the node does not receive the ACK frame, the data is sent again;

The communication process of the periodic service or the on-demand service includes:

S21. The coordinator sends a wake-up signal to the coordinator through the wake-up channel according to the set cycle;

S22, the node returns an ACK frame to the coordinator after receiving the wake-up signal;

S23. If the coordinator does not receive the ACK frame, resend the wake-up signal until the ACK frame is received;

S24. The coordinator sends a beacon frame to the node after receiving the ACK frame;

S25. After receiving the beacon frame, the node enters a waiting state to monitor the data channel;

S26. When the transmission channel is idle, the node sends data to the coordinator through the transmission channel;

S27. The coordinator returns an ACK frame to the node after receiving the data;

S28. If the node receives the ACK frame, the communication process ends, and if the node does not receive the ACK frame, it sends data again.

As a preferred solution, in S16, if the node has not received the ACK frame after sending the data several times, then the data is discarded.

As a preferred solution, in S28, if the node has not received the ACK frame after sending the data several times, the data is discarded.

A wake-up mechanism-based wireless body area network MAC protocol system includes a coordinator and several nodes wirelessly connected to the coordinator, and the nodes include a wireless wake-up circuit.

Beneficial effects: the present invention is based on the IEEE 802.15.6 communication standard, and each sensor node adds an additional ultra-low power consumption wake-up circuit, and the default state of the node is the sleep state, which can greatly reduce network energy consumption; according to different priorities It adopts different wake-up mechanisms, and adopts a conflict avoidance strategy of random backoff and waiting when multiple nodes wake up at the same time and encounters conflicts, which can ensure the real-time performance and reliability of high-priority services.

Description of drawings

Figure 1 is a comparison diagram of power consumption of wireless communication;

Fig. 2 is a schematic structural diagram of a wireless wake-up circuit in a specific embodiment of the present invention;

Fig. 3 is a schematic diagram of the state transition process of nodes in the present invention;

Fig. 4 is a schematic diagram of the channel allocation mode of the MAC protocol of the present invention;

Fig. 5 is the flow chart of the communication process of the random service in the communication method of the present invention;

Fig. 6 is a flow chart of the communication process of periodic services or on-demand services in the communication method of the present invention;

Fig. 7 is a schematic diagram of a network topology structure of a simulation experiment in a specific embodiment of the present invention;

Fig. 8 is a graph showing the variation of energy consumption with the data arrival time interval in the simulation experiment in the specific embodiment of the present invention;

FIG. 9 is a comparison diagram of delay performance of protocols in a simulation experiment in a specific embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Please refer to Figures 3 to 6, the wireless body area network MAC protocol based on the wake-up mechanism, hereinafter referred to as W-MAC, the data service in the wireless body area network is divided into three types: periodical service, on-demand service and random service A wake-up channel and a transmission channel are constructed between nodes, the wake-up channel is used to transmit wake-up signals, and the transmission channel is used to transmit data. Moreover, in the periodic service and on-demand service, the coordinator sends a wake-up signal to the node through the wake-up channel to make the node enter the wake-up state; in the random service, the node sends a wake-up signal to the coordinator through the wake-up channel, and enters the wake-up state; different nodes in When there is a channel conflict in the transmission data, the random service data is transmitted first, and then the periodic service data and on-demand service data are transmitted through the CSMA/CA competition mechanism.

Specifically, the contents and priorities of periodic services, on-demand services and random services are shown in Table 1.

Table 1 Business Classification

W-MAC is based on the IEEE 802.15.6 communication standard. Each sensor node adds an additional ultra-low power consumption wake-up circuit. The default state of the node is sleep state, which can greatly reduce network energy consumption; according to the characteristics of different priorities , adopting different wake-up mechanisms, and adopting a conflict avoidance strategy of random backoff and waiting when multiple nodes wake up at the same time encounter conflicts, which can ensure the real-time performance and reliability of high-priority services.

On the basis of the WBAN MAC protocol based on the wake-up mechanism, the present invention further provides a communication method, including a communication process of a random service and a communication process of a periodic service or an on-demand service.

The communication process of the random service includes S11 to S16.

S11. The node sends a wake-up signal to the coordinator through the wake-up channel.

S12. The coordinator returns an ACK frame after receiving the wake-up signal, and then sends a beacon frame to the node.

S13. If the node does not receive the ACK frame or the beacon frame, resend the wake-up signal until the beacon frame is received.

S14. The node sends data to the coordinator through the transmission channel.

S15. The coordinator returns an ACK frame to the node after receiving the data.

S16. If the node receives the ACK frame, the communication process ends. If the node does not receive the ACK frame, it sends the data again. If the node has sent the data several times but still does not receive the ACK frame, it discards the data.

The communication process of periodic service or on-demand service includes S21 to S28.

S21. The coordinator sends a wake-up signal to the coordinator through a wake-up channel according to a set period.

S22. The node returns an ACK frame to the coordinator after receiving the wake-up signal.

S23. If the coordinator does not receive the ACK frame, resend the wake-up signal until the ACK frame is received.

S24. The coordinator sends a beacon frame to the node after receiving the ACK frame.

S25. After receiving the beacon frame, the node enters a waiting state to monitor the data channel.

S26. When the transmission channel is idle, the node sends data to the coordinator through the transmission channel.

S27. The coordinator returns an ACK frame to the node after receiving the data.

S28. If the node receives the ACK frame, the communication process ends. If the node does not receive the ACK frame, it sends the data again. If the node sends the data several times but still does not receive the ACK frame, it discards the data.

Furthermore, the present invention also provides a WBAN MAC protocol system based on a wake-up mechanism, including a coordinator and several nodes wirelessly connected to the coordinator, the nodes include a wireless wake-up circuit, and the wireless wake-up circuit can be shown in the figure 2 shown.

The performance of the W-MAC is verified through a simulation experiment as follows.

Matlab is used as the simulation platform, and the network topology is shown in Figure 7. A star topology is adopted, and a total of 11 sensor nodes are set up, of which node 0 acts as the central node (coordinator), and the remaining 10 are general sensor nodes with different functions. Numbered from 1 to 10.

Sensor nodes use Poisson process to generate data flow, then the rate at which data packets arrive at the central node is λ, and the average arrival rate of the entire network model is (N-1)λ. Generally, different sensor nodes generate data at different rates. In order to simplify the simulation difficulty, we assume that different sensor nodes generate data at the same rate. In the simulation, we choose the communication channel frequency band of 2.4GHz, according to the actual situation of the realization process of the MAC protocol algorithm, other simulation parameters are set as shown in Table 2.

Table 2 Simulation parameter settings

Under the same simulation environment and parameters, W-MAC is compared with Wise-MAC protocol and S-MAC protocol.

First, verify the impact of data arrival time interval on network energy consumption, and the simulation results are shown in Figure 8. It can be seen from the figure that with the increase of the data arrival time interval, the energy consumption of the three protocols is gradually reduced. The competitive collisions are reduced, and the energy consumption is reduced. However, W-MAC consumes less energy overall than Wise-MAC and S-MAC because Wise-MAC and S-MAC periodically use preamble and RTS/MAC respectively. CTS, which consumes additional energy. W-MAC uses a wake-up mechanism, which can eliminate idle listening, thereby saving a lot of energy.

Next, compare the delay performance. As the data arrival time interval increases, the delay performance comparison results of the protocols are shown in Figure 9. By comparing the simulation diagrams, it can be found that as the data arrival time interval increases, Wise-MAC, The network delay of S-MAC and W-MAC is continuously reduced, and the network delay is the lowest when the data arrival time interval is 10s, but it is still higher than the MAC protocol proposed in this paper. The S-MAC protocol uses a mechanism based on CSMA/CA and adopts a typical RTS-CTS-DATA-ACK scheme, which introduces additional control overhead and thus increases delay. Although W-MAC also adopts the CSMA/CA mechanism, it adopts the wake-up mechanism and only has wireless wake-up delay and transmission delay. Therefore, compared with other MAC protocols, the total delay is the smallest.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (5)

1. the wireless body area network MAC protocol based on wake-up mechanism, in the wireless body area network data service be divided into periodic traffic, by Need business and random traffic three classes, it is characterised in that: the agreement constructs between coordinator and node wakes up channel and transmission Channel wakes up channel and is used for transmission wake-up signal, and transmission channel is used for transmission data；Also,

Coordinator sends wake-up signal so that node entrance is called out to node by waking up channel in periodic traffic and on-demand business The state of waking up；Wake-up signal is sent to coordinator by waking up channel in random traffic interior joint, and enters wake-up states；

Different nodes are when channel confliction occur in transmission data, prioritised transmission random traffic data, then pass through CSMA/CA and compete Mechanism transmission cycle business datum and on-demand business data.

2. the communication means of the wireless body area network MAC protocol based on wake-up mechanism as described in claim 1, it is characterised in that:

The communication process of the random traffic includes:

S11, node send wake-up signal to coordinator by waking up channel；

S12, coordinator return to ACK frame after receiving wake-up signal, then send beacon frame to node；

S13, wake-up signal is retransmitted if node does not receive ACK frame or beacon frame, until receiving beacon frame；

S14, node send data to coordinator by transmission channel；

S15, coordinator receive and return to ACK frame to node after data；

S16, communication process terminates if node receives ACK frame, if node does not receive ACK frame and sends data again；

The communication process of the periodic traffic or the on-demand business includes:

S21, coordinator send wake-up signal to coordinator by waking up channel according to the period of setting；

S22, node receive and return to ACK frame to coordinator after wake-up signal；

S23, wake-up signal is retransmitted if coordinator does not receive ACK frame, until receiving ACK frame；

S24, coordinator receive ACK frame and then send beacon frame to node；

S25, node monitor data channel into wait state after receiving beacon frame；

Node sends data to coordinator by transmission channel when S26, channel idle to be transmitted；

S27, coordinator receive and return to ACK frame to node after data；

S28, communication process terminates if node receives ACK frame, if node does not receive ACK frame and sends data again.

3. the wireless body area network MAC protocol based on wake-up mechanism as claimed in claim 2, it is characterised in that: in S16, if section Point, which has sent data several times and do not receive ACK frame yet, then abandons data.

4. the wireless body area network MAC protocol based on wake-up mechanism as claimed in claim 2, it is characterised in that: in S28, if section Point, which has sent data several times and do not receive ACK frame yet, then abandons data.

5. using the system of the wireless body area network MAC protocol based on wake-up mechanism as described in claim 1, it is characterised in that: Several nodes including coordinator and with coordinator wireless communication connection, node includes wireless awakening circuit.