WO2016026215A1

WO2016026215A1 - Multi-frequency flooding power-line carrier communication method

Info

Publication number: WO2016026215A1
Application number: PCT/CN2014/090291
Authority: WO
Inventors: 刘伟麟; 安春燕; 布米勒歌德; 李建岐; 陆阳; 赵涛; 赵勇; 陶峰; 高鸿坚; 杨冰; 褚广斌
Original assignee: 国家电网公司; 中国电力科学研究院
Priority date: 2014-08-18
Filing date: 2014-11-05
Publication date: 2016-02-25
Also published as: CN104144002B; CN104144002A

Abstract

Provided in the present invention is a multi-frequency flooding power-line carrier communication method. The method comprises the following steps: a power-line carrier communication system is initialized; a master station implements working frequency cognition for slave stations; and, the master station and the slave stations carry out multi-frequency data communication. The method selects different frequencies with respect to conditions of different slave stations/links on the basis of a frequency cognition and flooding technique, adapts to characteristics of power-line carrier network channels, increases access probability for the slave stations, and increase the range of network coverage.

Description

Multi-frequency flooding power line carrier communication method

Technical field

The invention relates to a method in the field of medium and low voltage power communication, in particular to a multi-frequency flooding power line carrier communication method.

Background technique

The power line carrier communication network has the advantage of no wiring, which can greatly reduce the network preparation cost. However, the power line carrier channel attenuation is affected by factors such as line length, network branch structure and impedance matching, and has the characteristics of large attenuation, large variation with local frequency, and frequency selective fading. In addition, the noise experienced by the slave station in the power line carrier communication network is colored noise, including not only the noise generated by the home appliance connected to the power line, but also the noise that the space radio signal is loaded onto the power line, having a large noise, changing anytime and anywhere, and frequency. Features such as selectivity. In short, the power line carrier communication environment is harsh, and it is necessary to adopt a robust communication method and system.

Frequency cognition technology and flooding technology are two robust communication technologies that can be applied in power line carrier communication networks to increase the reliability of communication. The frequency cognition technology is characterized by frequency selectivity of power line carrier channels and different channel attenuation characteristics. Based on cognitive technology, it finds the best communication frequency band for each communication link, increasing system speed and improving slave access. The purpose of probability and communication reliability. When flooding technology is adopted, any slave station forwards the data packet when it receives a data packet whose destination address is not its own address, and the destination secondary station may receive data packets from different paths multiple times. Therefore, the flooding network does not need to be networked, and the slave station does not have to have a memory capability, and the implementation is simple and robust. In addition, since all the slaves that receive the data packet participate in the forwarding, the data packet first received by the destination slave station can be regarded as the data packet from the best path, that is, the flooding technology does not need to be tested, calculated and analyzed in advance. You can find the best communication path for the slave.

In the prior art, the flooding technology is applied in the power line carrier communication network, and the flooding technology and routing technology are disclosed and compared. The flooding MAC protocol/routing algorithm suitable for PLC or smart grid is designed and evaluated. A flooding control method applied to a power line carrier communication network is also proposed. When the transmitting end does not receive a response message from the receiving end in a given time and the system rate is low, the transmitting end is restricted to the slave station. Time, and limit the number of flooding attempts in low-speed mode, throw away packets that do not need to respond to the slave, and so on.

Although the above techniques all apply flooding techniques to power line carrier communication networks, they are all applicable to single frequency communication networks. In an actual power line carrier communication network, the optimal operating frequencies of different links are different, and it is difficult to find a frequency to complete communication between most network sites. Therefore, it is necessary to provide a method for selecting the optimal operating frequency for each slave based on cognitive technology according to the condition of each slave in the network, and applying the multi-frequency communication technology and the flooding technology to the power line carrier communication network. A technical solution that fully utilizes the advantages of multi-frequency communication and flooding technology, increases the reliability of the network, and meets the real-time needs of the business.

Summary of the invention

In order to overcome the above drawbacks of the prior art, the present invention provides a multi-frequency flooding power line carrier communication method.

In order to achieve the above object, the present invention adopts the following technical solutions:

A multi-frequency flooding power line carrier communication method is improved in that the method comprises the following steps:

I. Initialization of the power line carrier communication system;

II. The primary station realizes the working frequency awareness of the slave station;

III. The primary station performs multi-frequency data communication with the secondary station.

Further, the step I includes determining that the frequency of the single or multiple equal bandwidths of the power line carrier communication system is a default operating frequency; the default operating frequencies overlap or do not overlap each other.

Further, the frequency is any frequency within a low frequency, an intermediate frequency, and/or a high frequency.

Further, the low frequency range is less than 500 kHz, the intermediate frequency ranges from 500 kHz to 1.6 MHz, and the high frequency ranges from greater than 1.6 MHz.

Further, in the step II, the primary station determines the working frequency of the secondary station according to the response of the MAC layer test data packet, including the following steps:

S201. The primary station sequentially selects a test slave station, tests a hop count, and selects a test working frequency according to the default working frequency, and adds a test frequency of each hop in the frequency map of the MAC layer test data packet. Transmitting a preamble signal by using the first hop test working frequency in a time slot corresponding to the first hop test working frequency, and transmitting a MAC layer test data packet by using the first hop test working frequency in the data slot;

S202. The slave station determines a test working frequency according to the preamble signal, and receives the MAC layer test data packet by using the test working frequency in a data slot.

S203, the slave station receives the MAC layer test data packet, determines whether the destination address of the MAC layer test data packet is itself, and if so, proceeds to step S205;

Otherwise, it is determined whether the remaining hop count is zero. If not, the process proceeds to step S204, otherwise the MAC layer test data packet is discarded.

S204. When the slave station receives the remaining hop count of the MAC layer test data packet is not zero, the slave station searches for a next hop in the frequency map of the MAC layer test data packet according to the current hop count. The working frequency is tested, the current hop count is increased by one, and the remaining hop count is decremented by one. The preamble signal is sent to the next hop test working frequency in the corresponding time interval of the next hop test working frequency in the preamble time slot of the next time slice to The next slave station sends the MAC layer test data packet to the next slave station through the next hop test working frequency in the data slot, and returns to step S202;

S205. The slave station determines a response time slice according to the remaining hop count, determines a frequency map of the MAC layer test response data packet according to the frequency map of the MAC layer test data packet, and searches for a first response working frequency of the test response. Transmitting, by the first hop test, the preamble signal by the first hop test response working frequency in the first time hop test response working frequency corresponding to the working time slot of the response time slice, and responding by using the first hop test response in the data time slot Frequency sending MAC layer test response data packet, returning to step S202;

S206. The primary station selects an uplink working frequency and a downlink working frequency for each slave station according to the response condition of the MAC layer test data packet.

S207. When selecting an operating frequency for each slave station, the master station establishes a record uplink hop count for each slave station, Routing information entries of uplink working frequency, downlink hop count, and downlink operating frequency;

When the communication frequency is selected for each link, the primary station establishes a routing information entry for each secondary station to record the number of uplink hops, the uplink each hop operating frequency, the downlink hop count, and the downlink each hop operating frequency.

Further, the MAC layer data packet includes a packet header, a payload, and a frequency map.

Further, the preamble time slot allocates a preamble time for each default working frequency, where the preamble time includes a preamble sending time, a guard time, and a processing time.

Further, the frequency map includes an operating frequency of each hop during communication between the primary station and the secondary station.

Further, the routing information table includes a downlink hop count and a downlink working frequency entry, and an uplink hop count and an uplink working frequency entry.

Further, the step III includes the following steps:

S301. The primary station views a routing information table, and adds a working frequency of each hop in a frequency map of the MAC layer data packet.

S302. In the first time slice, the primary station sends a preamble in a time corresponding to the first hop working frequency in the preamble time slot, and sends the MAC layer data packet in the data transmission time slot by using the first hop working frequency.

S303. The slave station sequentially adjusts the working frequency to the default frequency band to detect the preamble. If the slave station does not detect the preamble, it remains silent in the current time slice, otherwise, in the data transmission time slot. Receiving the MAC layer data packet by detecting a preamble frequency band;

S304, the slave station determines whether it is the destination slave station according to the MAC layer data packet, if yes, proceeds to step S309, otherwise proceeds to step S305;

S305, the slave station receives the MAC layer data packet, determines whether the remaining hop count of the MAC layer data packet is zero, if it is zero, proceeds to step S306, otherwise proceeds to step S307;

S306. The slave station that receives the MAC layer data packet whose destination address is not itself and the remaining hop count is zero, discards the MAC layer data packet, and does not perform any processing;

S307. The slave station that receives the MAC layer data packet whose destination address is not itself and whose remaining hop count is not zero is used to find a forwarding working frequency according to the frequency map and the current hop count in the MAC layer data packet, and the current hop count is obtained. Add one, the remaining hop count is reduced by one, and the MAC layer data packet is ready to be forwarded;

S308. Enter a next time slice, and the slave station that is to forward the MAC layer data packet sends a preamble in a time corresponding to the forwarding working frequency in the preamble time slot, and sends the data through the forwarding working frequency in the data transmission time slot. The MAC layer data packet returns to step S303;

S309. The destination slave station receives the MAC layer data packet.

Compared with the prior art, the beneficial effects of the present invention are:

1. The method of the present invention uses frequency cognition technology to select different frequencies for different slave stations/links, adapts to the channel characteristics of the power line carrier network, increases the access probability of the slave station, and improves the network coverage.

2. The method of the present invention enables multi-frequency communication through a preamble time slot, and can coordinate the transmission/reception operating frequency without any memory of the slave station, and is simple and robust.

3. In the method of the present invention, the MAC layer data packet carries the frequency map, and the slave station that receives the destination address not itself and the remaining hop count is not 0 data packet can decide to forward the data packet according to the frequency map and the current hop count. The working frequency can support end-to-end communication with multiple working frequencies without any memory, and the implementation is simple and reliable.

4. In the method of the present invention, the multi-frequency flooding communication mechanism can not only support single-frequency flooding of multiple frequencies, but also support multi-frequency flooding including multiple working frequencies from end to end;

The method of the invention inherits the advantage that the flooding technology does not need networking, and can quickly adapt to the change of the power grid structure; inherits the advantage that the flooding technology can transmit data to the destination slave station through the optimal path, and can be used to support real-time performance. Requires higher control services, etc. The method of the present invention has a large path gain and synergistic gain.

5. The method of the invention combines advanced frequency cognition, flooding technology and multi-frequency communication technology to realize power line carrier communication, and satisfies power line carrier communication including smart grid service including distribution automation, power consumption information collection, distributed power control, etc. Delay and reliability requirements.

6. The method of the present invention can be applied to a master-slave network including one primary station and a plurality of secondary stations, and can also be extended to a network including a plurality of primary stations and a plurality of secondary stations, and the present invention can improve the conventional power line carrier communication. The main problems of poor communication reliability, low coverage of the station, poor adaptability and large delay are suitable for the future development of the PLC carrier network.

DRAWINGS

1 is a schematic diagram of a working frequency range of a power line carrier communication in the embodiment;

2 is a schematic structural diagram of a preamble slot in the present invention;

3 is a schematic diagram of communication between a primary station and a secondary station in the embodiment;

4 is a schematic structural diagram of a MAC layer data packet in the present invention;

FIG. 5 is a flowchart of the work performed by the primary station to complete the frequency awareness of the secondary station according to the present invention; FIG.

6 is a flow chart of the operation of the primary station in the process of multi-frequency data communication between the primary station and the secondary station in the present invention;

Figure 7 is a flow chart showing the operation of the slave station in the present invention.

detailed description

The invention will now be further described with reference to the accompanying drawings.

The invention provides a multi-frequency flood line carrier communication (PLC) method based on frequency cognition and flooding technology. The method of the present invention can be applied to star and tree network topologies.

The method of the present invention is based on frequency cognition technology, and the primary station realizes the knowledge of the network topology environment and the communication working frequency, from the default frequency bands of several equal bandwidths distributed in the range of several tens of kilohertz to several tens of megahertz. The slave/link finds the communicable working frequency, adapts to the poor communication environment of the PLC, improves the access probability of the slave station, and satisfies the delay and reliability requirements of the communication. The primary station implements frequency awareness. The slave station does not need to have any learning, storage and computing capabilities, and does not need to judge the optimal working frequency. It only needs to receive the data packets sent by the primary station for corresponding operations.

The method of the present invention is based on a multi-frequency flooding technique that inherits the characteristics of multi-frequency techniques and single-frequency flooding techniques. Including: flooding technology does not need to be networked, can adapt to the change quickly when the network status changes, and the adaptability is strong; flooding technology can ensure that the power line carrier signal transmission path is the best path, which can support the relatively high delay requirement. Control services, etc.; multi-frequency flooding techniques have large path gains and synergistic gains.

The above multi-frequency flooding power line carrier communication method comprises the following steps:

Step 1: Initialization of the power line carrier communication system;

Step 2: The primary station realizes the working frequency awareness of the slave station;

Step 3: The primary station and the secondary station perform multi-frequency data communication.

Step 1 includes: determining a frequency of the plurality of equal bandwidths of the power line carrier communication system as a default operating frequency; the default operating frequencies overlapping or not overlapping each other.

The above frequencies are any frequencies within the low frequency, intermediate frequency and/or high frequency. The low frequency range is less than 500 kHz, the intermediate frequency ranges from 500 kHz to 1.6 MHz, and the high frequency ranges from greater than 1.6 MHz.

In step 2, the primary station determines the working frequency of the secondary station according to the response condition of the MAC layer test data packet; as shown in FIG. 5, FIG. 5 is a working flow chart of the primary station completing the secondary station frequency awareness according to the present invention, as shown in FIG. As shown in FIG. 6 is a working flow chart of the slave station in the present invention, and the master station completes the slave station frequency awareness specifically including the following steps:

S201, the primary station determines whether the frequency awareness of all the slave stations has been completed, then proceeds to step S209, otherwise selects the test slave station, proceeds to step S202;

S202: The primary station selects a test frequency, including a test hop count and a working frequency of each hop, and adds a test frequency of each hop in a frequency map of the MAC layer test data packet, and the first hop test in the lead time slot of the primary station Sending a preamble signal through the first hop test working frequency in a working frequency corresponding period, and transmitting a MAC layer test data packet in the data slot by using the first hop test working frequency;

S203. In each time slice, the slave station determines a test working frequency according to the preamble signal, and receives the MAC layer test data packet by using the test working frequency in a data slot.

S204, the slave station receives the MAC layer test data packet, determines whether the destination address of the MAC layer test data packet is itself, and if so, proceeds to step S206;

Otherwise, it is determined whether the remaining hop count is zero, if not zero, then proceeds to step S205, otherwise discards the MAC layer test data packet, proceeds to step S203;

S205. When the slave station receives the remaining hop count of the MAC layer test data packet is not zero, the slave station searches for the next hop test working frequency in the frequency map of the MAC layer data packet according to the current hop count, and The current hop count is increased by one, and the remaining hop count is decremented by one. The preamble signal is sent to the next slave station through the next hop test working frequency in the corresponding time of the next hop test working frequency in the preamble time slot of the next time slice. Transmitting the MAC layer test data packet to the next slave station by using the next hop test working frequency in the data slot, and returning to step S203;

S206. The slave station determines a response time slice according to the remaining hop count, determines a frequency map of the MAC layer test response data packet according to the frequency map of the MAC layer test data packet, and searches for a first response working frequency of the test response. Transmitting, by the first hop test, a preamble signal by using the first hop test response working frequency, and responding by using the first hop test in a data slot, in a first time hop test response working frequency corresponding time period of the response time slice. The working frequency sends the MAC layer test response data packet, and returns to step S203;

S207. The primary station receives the MAC layer test response data packet, and the primary station determines whether the tested communication station has a testable communication frequency greater than a predetermined value, and then selects a working frequency according to the MAC layer test response data packet for the test secondary station, and proceeds to the step. S208;

Otherwise, the primary station determines whether all frequencies have been tested, and if so, ends the frequency cognition of the test slave, proceeds to step S201, otherwise proceeds to step S202;

S208, when selecting a working frequency for each slave station, the primary station establishes a routing information entry for recording the uplink hop count, the uplink working frequency, the downlink hop count, and the downlink working frequency for each slave station, and proceeds to step S201;

When the communication frequency is selected for each link, the primary station establishes, for each secondary station, a routing information entry that records the number of uplink hops, the uplink hops, the downlink hops, and the downlink hops, and proceeds to step S201. .

S209. Perform the frequency cognition work of all the slave stations through the above steps.

The foregoing MAC layer data packet includes a packet header, a payload, and a frequency map; the preamble time slot is a default operating frequency allocation preamble time, and the preamble time includes a preamble transmission time, a guard time, and a processing time. The frequency map includes an operating frequency of each hop in the communication process between the primary station and the secondary station in the routing information table established by the primary station.

The routing information table of the primary station includes two entries, the first entry includes a downlink hop count and a downlink operating frequency, and the second entry includes an uplink hop count and an uplink working frequency.

The principle that the primary station selects the operating frequency for the secondary station may be, but is not limited to, the principle of minimum hop count, or the principle of maximum received signal to noise ratio, etc., depending on the requirements of the communication system.

In this embodiment, a routing information table of a primary station is provided, including a plurality of routing information tables in a single frequency flooding network and an end-to-end multi-frequency flooding network, as shown in Table 1 below, and Table 1 is different. The routing information table of the primary station in the frequency single-frequency flooding network; as shown in Table 2 below, Table 2 is an example of routing information table of the primary station in the multi-frequency flooding network including multiple different frequencies from end to end;

Table 1 Example of routing information table of the primary station in a plurality of single frequency flooding networks with different frequencies

Table 2: End-to-end routing information table instance table of the primary station in a multi-frequency flooding network with multiple frequencies

In step 3, the primary station and the secondary station perform multi-frequency data communication, as shown in Figures 6 and 7, and Figures 6 and 7 are respectively working flowcharts of the slave station and the master station in the process of multi-frequency data communication; the master station and the slave station The station performs multi-frequency data communication specifically including the following steps:

S301. The primary station views the routing information table, and adds the working frequency of each hop to the frequency map of the MAC layer data packet.

S302. In the first time slice, the primary station sends a preamble in a time corresponding to the first hop working frequency in the preamble slot, and sends a MAC layer data packet in the data transmission slot by using the first hop working frequency.

S308. Enter a next time slice, and the slave station that is to forward the MAC layer data packet sends a preamble in a time corresponding to the forwarding working frequency in the preamble time slot, and sends the foregoing in a data transmission time slot by using a forwarding working frequency. MAC layer data packet, returning to step S303;

S309. The destination slave station receives the MAC layer data packet.

As shown in FIG. 1 , FIG. 1 is a schematic diagram of a working frequency range of a power line carrier communication in the embodiment; in this embodiment, an operating frequency range of the power line carrier communication system spans a high frequency, an intermediate frequency, and a low frequency; in this embodiment, first, Select several equal bandwidth frequencies as the default frequency for system operation. The default frequencies may or may not overlap each other.

In this embodiment, the preamble time slot is used to implement multi-frequency communication. When multiple working frequencies are used, the receiving end knows that the transmitting end uses one of the default operating frequencies to transmit data, but it is not sure which operating frequency, and the receiving end passes the pair. The detection of the leading time slot knows the working frequency that the transmitting end specifically uses.

2 is a schematic diagram of a structure of a preamble slot in the present invention; in a preamble slot, a preamble time is allocated for each default operating frequency; a preamble time of any frequency band includes a preamble transmission time, a guard time, and a processing time. Since the default frequency used by the present invention is of equal bandwidth, the lead times for all frequencies are the same.

In the method of the present invention, the preamble time slot is located in front of the data transmission time slot for coordinating the operating frequency of the data receiving/transmitting station. For example, if the primary station decides to send the data packet through the second default frequency, the primary station sends the preamble in the time corresponding to the second default frequency, if the secondary station passes the time corresponding to the second default frequency. If the two default frequencies detect the preamble, then they receive the data through the second default frequency in the data transmission time slot.

As shown in FIG. 3, FIG. 3 is a flow chart of communication between a primary station and a secondary station in the present embodiment. In combination with the communication process of the present invention, the primary station and the secondary station, the secondary station 2, and the secondary station 3 are used in the present embodiment. The communication process of the station is further described, including the following steps:

S1. In the first time slice, the primary station sends a preamble in a time corresponding to the first hop operating frequency in the preamble time slot, and sends a MAC layer data packet in the data transmission time slot by using the first hop working frequency;

The slave station 1, the slave station 2, the slave station 3 and the destination slave station sequentially adjust the operating frequency to the default frequency bands to detect the preamble; the slave station 2, the slave station 3 and the destination slave station do not detect the preamble Remaining silent in the current time slice; detecting the preamble from the station, receiving the MAC layer data packet in the data transmission time slot by detecting the preamble frequency band;

S2. The slave station that receives the MAC layer data packet whose destination address is not itself and whose remaining hop count is not 0 is used to find the forwarding working frequency according to the frequency map and the current hop count in the MAC layer data packet, and the current hop count is added. First, the remaining hop count is reduced by one, and the MAC layer data packet is ready to be forwarded;

S3. In the second time slice, the slave station transmits the preamble in a time corresponding to the forwarding working frequency in the preamble time slot, and sends the MAC layer data packet in the data transmission time slot by using the forwarding working frequency;

The primary station, the secondary station 2, the secondary station 3, and the destination slave station sequentially adjust the operating frequency to the default frequency band to detect the preamble; the primary station, the secondary station 3, and the destination secondary station do not detect the preamble. Keep silent in the current time slice; the second preamble is detected by the station 2, and the MAC layer data packet is received in the data transmission time slot by detecting the preamble frequency band;

S4. The slave station 2 that receives the MAC layer data packet whose destination address is not its own and the remaining hop count is not 0, searches for the forwarding working frequency according to the frequency map and the current hop count in the MAC layer data packet, and adds the current hop count. First, preparing to forward the MAC layer data packet;

S5. In the third time slice, the slave station sends the time corresponding to the working frequency in the preamble time slot. Sending a preamble, sending the MAC layer data packet by forwarding a working frequency in a data transmission time slot;

The primary station, the secondary station 1, the secondary station 2, and the destination secondary station sequentially adjust the operating frequency to the default frequency band to detect the preamble; the primary station, the secondary station 1 and the secondary station 2 do not detect the preamble. Keep silent in the current time slice; the destination slave detects the preamble, and receives the MAC layer data packet by detecting the preamble frequency band in the data transmission time slot;

S6. The destination slave station receives the MAC layer data packet.

4 is a schematic structural diagram of a MAC layer data packet in the present invention; the MAC layer data packet includes a packet header, a frequency map, and a load; and the frequency map includes an operating frequency f(1) of each hop when the primary station and the destination slave station communicate, f(2)...f(n).

For example, if the default operating frequency of the network is 16, then 4 bits can be used to represent a frequency; if the maximum hop count supported by the network is 5 hops, the frequency map occupies at least 20 bits. When the primary station communicates with a certain slave station, according to the frequency cognition result, the primary station searches for the used frequency from the routing table and adds it to the frequency map. In this embodiment, the frequency map is loaded with five working frequencies f(1), f (2)...f(5). If a slave receives a packet with the hop count of 1 and the destination address is not its own, the packet hop count is increased to 2, and the packet is represented by the frequency indicated by the 5th to 8th bits in the frequency map. Send it out.

Finally, it should be noted that the above embodiments are only for explaining the technical solutions of the present invention and are not limited thereto, although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be The invention is to be construed as being limited by the scope of the appended claims.

Claims

A multi-frequency flooding power line carrier communication method, characterized in that the method comprises the following steps:

I. Initialization of the power line carrier communication system;

II. The primary station realizes the working frequency awareness of the slave station;

III. The primary station performs multi-frequency data communication with the secondary station.
The method of claim 1 wherein said step 1 comprises: determining a frequency of a single or plurality of equal bandwidths of said power line carrier communication system as a default operating frequency; said default operating frequencies overlapping or not overlapping each other; .
The method of claim 2 wherein said frequency is any frequency within a low frequency, an intermediate frequency, and/or a high frequency.
The method of claim 3 wherein said low frequency ranges from less than 500 kHz, said intermediate frequency ranges from 500 kHz to 1.6 MHz, and said high frequency ranges from greater than 1.6 MHz.
The method of claim 1, wherein in the step II, the primary station determines the operating frequency of the slave station according to the response of the MAC layer test data packet, including the following steps:

S201. The primary station sequentially selects a test slave station, tests a hop count, and selects a test working frequency according to the default working frequency, and adds a test frequency of each hop in the frequency map of the MAC layer test data packet. Transmitting a preamble signal by using the first hop test working frequency in a time slot corresponding to the first hop test working frequency, and transmitting a MAC layer test data packet by using the first hop test working frequency in the data slot;

S202. The slave station determines a test working frequency according to the preamble signal, and receives the MAC layer test data packet by using the test working frequency in a data slot.

S203, the slave station receives the MAC layer test data packet, determines whether the destination address of the MAC layer test data packet is itself, and if so, proceeds to step S205;

Otherwise, it is determined whether the remaining hop count is zero. If not, the process proceeds to step S204, otherwise the MAC layer test data packet is discarded.

S204. When the slave station receives the remaining hop count of the MAC layer test data packet is not zero, The slave station searches for the next hop test working frequency in the frequency map of the MAC layer test data packet according to the current hop count, and increases the current hop count by one and the remaining hop count by one, in the leading time slot of the next time slice. Sending, by the next hop test working frequency, the preamble signal to the next slave station in the corresponding time of the next hop test working frequency, and sending the MAC layer test data packet to the next hop test working frequency in the data slot to The next slave station returns to step S202;

S205. The slave station determines a response time slice according to the remaining hop count, determines a frequency map of the MAC layer test response data packet according to the frequency map of the MAC layer test data packet, and searches for a first response working frequency of the test response. Transmitting, by the first hop test, the preamble signal by the first hop test response working frequency in the first time hop test response working frequency corresponding to the working time slot of the response time slice, and responding by using the first hop test response in the data time slot Frequency sending MAC layer test response data packet, returning to step S202;

S206. The primary station selects an uplink working frequency and a downlink working frequency for each slave station according to the response condition of the MAC layer test data packet.

S207. When selecting a working frequency for each slave station, the primary station establishes, for each slave station, a routing information entry that records an uplink hop count, an uplink working frequency, a downlink hop count, and a downlink working frequency.

When the communication frequency is selected for each link, the primary station establishes a routing information entry for each secondary station to record the number of uplink hops, the uplink each hop operating frequency, the downlink hop count, and the downlink each hop operating frequency.
The method of claim 5 wherein said MAC layer data packet comprises a header, a payload and a frequency map.
The method of claim 6 wherein said preamble time slot allocates a preamble time for each default operating frequency, said preamble time including a preamble transmission time, a guard time, and a processing time.
The method of claim 6 wherein said frequency map comprises an operating frequency of each hop during communication between said primary station and said secondary station.
The method of claim 5, wherein the routing information table comprises a downlink hop count and a downlink working frequency entry, and an uplink hop count and an uplink working frequency entry.
The method of claim 1 wherein said step III comprises the steps of:

S301. The primary station views a routing information table, and adds a working frequency of each hop in a frequency map of the MAC layer data packet.

S302. In the first time slice, the primary station sends a preamble in a time corresponding to the first hop working frequency in the preamble time slot, and sends the MAC layer data packet in the data transmission time slot by using the first hop working frequency.

S303. The slave station sequentially adjusts the working frequency to the default frequency band to detect the preamble. If the slave station does not detect the preamble, it remains silent in the current time slice, otherwise, in the data transmission time slot. Receiving the MAC layer data packet by detecting a preamble frequency band;

S304, the slave station determines whether it is the destination slave station according to the MAC layer data packet, if yes, proceeds to step S309, otherwise proceeds to step S305;

S305, the slave station receives the MAC layer data packet, determines whether the remaining hop count of the MAC layer data packet is zero, if it is zero, proceeds to step S306, otherwise proceeds to step S307;

S306. The slave station that receives the MAC layer data packet whose destination address is not itself and the remaining hop count is zero, discards the MAC layer data packet, and does not perform any processing;

S307. The slave station that receives the MAC layer data packet whose destination address is not itself and whose remaining hop count is not zero is used to find a forwarding working frequency according to the frequency map and the current hop count in the MAC layer data packet, and the current hop count is obtained. Add one, the remaining hop count is reduced by one, and the MAC layer data packet is ready to be forwarded;

S308. Enter a next time slice, and the slave station that is to forward the MAC layer data packet sends a preamble in a time corresponding to the forwarding working frequency in the preamble time slot, and sends the data through the forwarding working frequency in the data transmission time slot. The MAC layer data packet returns to step S303;

S309. The destination slave station receives the MAC layer data packet.