Medium-distance wireless transmission method

Abstract

The invention discloses a middle-distance wireless transmission method which comprises the following steps: S1, terminal equipment sends a connection request frame through a master control frequency band, and the connection request frame comprises an equipment ID and a signal strength RSSI value; s2, after the gateway receives the request, calculating a channel quality index based on an RSSI value, and dynamically allocating the channel quality index to an auxiliary frequency band based on a result; s3, the main control frequency band adopts FSK modulation to transmit a control instruction, and the auxiliary frequency band adopts QPSK-OFDM modulation to transmit a data packet; s4, during data transmission, collecting channel parameters once every 10ms, if the packet loss rate is gt; and 5%, the auxiliary frequency band is switched to pi / 4-DQPSK modulation transmission. The method has the beneficial effects that the channel quality index is calculated based on the RSSI value and is dynamically allocated to the auxiliary frequency band or the main control frequency band based on the result, a dual-frequency-band cooperative transmission mechanism is ingeniously adopted, and the modulation mode is dynamically switched by monitoring the channel quality in real time, so that the reliability of data packet transmission is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of Internet of Things, in particular to a middle-distance wireless transmission method. BACKGROUND

[0002] The existing single-band middle-distance wireless transmission has the following main defects: firstly, the single-band transmission is limited by the available spectrum width and cannot meet the large-scale data transmission demand of modern power systems. Traditional wireless communication technology often shows problems such as insufficient bandwidth and transmission delay when facing large-scale data transmission, and this bandwidth limitation is particularly obvious in scenarios that require video or a large amount of sensing data to be transmitted; secondly, in a complex electromagnetic environment, single-band devices are easily affected by the same frequency interference, for example, the 2.4GHz frequency band has Bluetooth, WiFi and other short-distance wireless technologies, and household microwave ovens are also in this frequency band range, which results in a large number of users, and the compatibility and coexistence of devices are problems that need to be faced, while the 433MHz frequency band is interfered by interphone, vehicle-mounted communication devices, etc., and adopts single frequency point operation, which cannot effectively resist the multipath effect caused by shielding, resulting in unreliable communication. SUMMARY

[0003] The purpose of the present application is to overcome the shortcomings of the prior art and provide a middle-distance wireless transmission method.

[0004] The purpose of the present application is achieved by the following technical solution: a middle-distance wireless transmission method, comprising the following steps:

[0005] S1: the terminal device sends a connection request frame through the main control frequency band, which contains the device ID and the signal strength RSSI value;

[0006] S2: after the gateway receives the request, the channel quality index is calculated based on the RSSI value , and based on the result, it is dynamically allocated to the auxiliary frequency band;

[0007] S3: the main control frequency band uses FSK modulation to transmit control instructions, and the auxiliary frequency band uses QPSK-OFDM modulation to transmit data packets;

[0008] S4: during data transmission, the channel parameters are collected every 10ms, and if the packet loss rate is >5%, the auxiliary frequency band is switched to π / 4-DQPSK modulation transmission.

[0009] Preferably, in step S2, the channel quality index further comprises the following steps:

[0010] S21: filter the input RSSI value to obtain ;

[0011] S22: calculate the path loss,

[0012] ;

[0013] wherein, is the reference distance, is the actual distance between the terminal and the gateway, is the path loss under the reference distance, is the path loss exponent, is a random variable caused by shadow fading, obeying normal distribution , is the standard deviation of shadow fading,

[0014] S23: calculate the environmental compensation value,

[0015] ;

[0016] wherein, is the weather compensation value, is the obstacle compensation value;

[0017] S24: calculate the channel quality index ,

[0018] ;

[0019] ;

[0020] ;

[0021] wherein, is the average packet loss rate in the past 60 seconds

[0022] Preferably, in step S2, when , the link is failed; when , the link quality level is poor, and the link is assigned to the primary frequency band; when , the link quality level is medium, and the link is assigned to the secondary frequency band; when , the link quality level is good, and the link is assigned to the secondary frequency band; when , the link quality level is excellent, and the link is assigned to the secondary frequency band.

[0023] Preferably, in step S3, the specific steps of the primary frequency band transmitting the control instruction are as follows:

[0024] S31: encapsulate the instruction, and convert the digital signal into a constant envelope analog signal;

[0025] S32: perform Gaussian pulse shaping,

[0026] ;

[0027] ;

[0028] S33: The receiving end receives and then carries out time delay frequency discrimination demodulation and clock synchronization.

[0029] Preferably, in step S33, the formula of time delay frequency discrimination demodulation is:

[0030] ;

[0031] wherein, is the frequency discrimination sensitivity.

[0032] Preferably, in step S33, the specific steps of clock synchronization are:

[0033] S33.1: Collecting signals at three time points,

[0034] ;

[0035] wherein, is the bit period, is the sampling time

[0036] calculating the lead-lag voltage difference,

[0037] ;

[0038] carrying out cumulative average,

[0039] ;

[0040] S33.2: Carrying out symbol checking,

[0041] ;

[0042] ;

[0043] S33.3: Updating the phase of the sampling clock,

[0044] .

[0045] The present application has the following advantages: the present application calculates the channel quality index based on the RSSI value , and dynamically allocates to the auxiliary frequency band or the main frequency band based on the result, ingeniously adopts the dual-band cooperative transmission mechanism, dynamically switches the modulation mode through real-time monitoring of the channel quality, and improves the reliability of data packet transmission. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is the structural schematic diagram of the method flow of the medium distance wireless transmission method. DETAILED DESCRIPTION

[0047] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Generally, the components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative work fall within the scope of protection of the present application.

[0049] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0050] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0051] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly understood by those skilled in the art, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0052] In the description of the present application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "arrangement", "installation", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0053] In the present embodiment, as shown in Figure 1 A medium distance wireless transmission method, comprising the following steps:

[0054] S1: The terminal device sends a connection request frame through the master frequency band, containing the device ID and signal strength RSSI value;

[0055] S2: After the gateway receives the request, it calculates the channel quality index based on the RSSI value , and dynamically allocates to the auxiliary frequency band based on the result;

[0056] S3: The master frequency band uses FSK modulation to transmit control instructions, and the auxiliary frequency band uses QPSK-OFDM modulation to transmit data packets;

[0057] S4: During data transmission, channel parameters are collected every 10ms, and if the packet loss rate is >5%, the auxiliary frequency band switches to π / 4-DQPSK modulation transmission. Based on the RSSI value, the channel quality index is calculated , and based on the result, it is dynamically allocated to the auxiliary frequency band or the master frequency band, and the dual-band cooperative transmission mechanism is ingeniously used, which dynamically switches the modulation mode by real-time monitoring of channel quality, improving the reliability of data packet transmission.

[0058] Further, in step S2, the channel quality index is calculated and further comprises the following steps:

[0059] S21: Filter the input RSSI value to obtain ; Specifically, the main function of filtering the input RSSI value is to eliminate impulse noise.

[0060] S22: Calculate the path loss,

[0061] ;

[0062] wherein, is the reference distance, is the actual distance between the terminal and the gateway, is the path loss under the reference distance, is the path loss index, is a random variable caused by shadow fading, which follows a normal distribution , is the standard deviation of shadow fading. Specifically, the path loss index is dynamically selected according to the environment, for example, 3.2 in urban areas and 2.7 in suburban areas, and the typical value is 4.8dB.

[0063] S23: Calculate the environmental compensation value,

[0064] ;

[0065] wherein, is the weather compensation value, obstacle compensation value;

[0066] S24: calculating channel quality index ,

[0067] ;

[0068] ;

[0069] ;

[0070] wherein, is the average packet loss rate in the past 60 seconds. Specifically, in step S23, when the weather is sunny, is 0; when the weather is rainy, is 2.3; when the weather is snowy, is 4.1; when the weather is foggy, is 1.2. When there is no obstacle blocking, is 0; when the obstacle is metal, is 8.7; when the obstacle is concrete, is 6.2; when the obstacle is glass, is 3.1.

[0071] Further, in step S2, when , the link is invalid; when , the link quality level is poor, and the primary frequency band is allocated; when , the link quality level is medium, and the secondary frequency band is allocated; when , the link quality level is good, and the secondary frequency band is allocated; when , the link quality level is excellent, and the secondary frequency band is allocated.

[0072] In this embodiment, in step S3, the specific steps of the primary frequency band transmitting control instructions are as follows:

[0073] S31: packaging the instructions and converting the digital signal into a constant envelope analog signal;

[0074] S32: performing Gaussian pulse shaping, which mainly compresses the signal bandwidth and suppresses adjacent channel interference,

[0075] ;

[0076] ;

[0077] S33: after receiving, the receiving end performs delay frequency discrimination demodulation and clock synchronization. Specifically, in step S33, the formula for delay frequency discrimination demodulation is:

[0078] ;

[0079] wherein, is the frequency discrimination sensitivity, which mainly converts the frequency variation into voltage variation to recover the original bit. Further, in step S33, the main function of the clock synchronization is to eliminate the sampling clock offset and reduce the bit error rate. The specific steps of the clock synchronization are as follows:

[0080] S33.1: Collecting signals at three time points,

[0081] ;

[0082] wherein, is the bit period, is the th sampling time

[0083] Calculate the lead-lag voltage difference,

[0084] ;

[0085] Perform cumulative average,

[0086] ;

[0087] S33.2: Perform symbol checking,

[0088] ;

[0089] ;

[0090] S33.3: Update the phase of the sampling clock,

[0091] .

[0092] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to part of the technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A medium-distance wireless transmission method, characterized by: The following steps are involved: S1: The terminal device sends a connection request frame through the master frequency band, which includes the device ID and signal strength RSSI value; S2: After receiving the request, the gateway calculates the channel quality index based on the RSSI value , and dynamically allocate to auxiliary frequency bands based on the results; S3: The main control band uses FSK modulation to transmit control commands, and the auxiliary band uses QPSK-OFDM modulation to transmit data packets; S4: During data transmission, channel parameters are collected every 10 ms. If the packet loss rate is greater than 5%, the auxiliary frequency band is switched to π / 4-DQPSK modulation transmission.

2. The mid-range wireless transmission method according to claim 1, wherein: In step S2, the channel quality index is calculated The following steps are also included: S21: Filter the input RSSI value to obtain ; S22: Calculate path loss, ； in, is the reference distance, is the actual distance between the terminal and the gateway, is the path loss at the reference distance (31.5dB), is the path loss exponent (dynamically selected based on the environment classifier, e.g., 3.2 in urban areas and 2.7 in suburban areas), is a random variable caused by shadow fading and obeys the normal distribution , is the standard deviation of shadow fading (typical value 4.8dB, fixed), S23: Calculate the environmental compensation value, ； in, is the weather compensation value, is the obstacle compensation value; S24: Calculate channel quality index , ； ； ； in, The average packet loss rate in the past 60 seconds.

3. The mid-range wireless transmission method according to claim 2, wherein: In step S2, when When the link fails; when When the link quality level is poor, it is allocated to the master frequency band; when When the link quality level is medium, it is allocated to the auxiliary frequency band; when When the link quality level is good, it is allocated to the auxiliary frequency band; when When the link quality level is excellent, it is allocated to the auxiliary frequency band.

4. The mid-range wireless transmission method according to claim 3, wherein: In step S3, the specific steps of transmitting the control instruction of the master frequency band are as follows: S31: Encapsulate the instruction and convert the digital signal into a constant envelope analog signal; S32: Perform Gaussian pulse shaping, ； ； S33: After receiving, the receiving end performs delayed frequency detection demodulation and clock synchronization.

5. The mid-range wireless transmission method according to claim 4, wherein: In step S33, the formula for delayed frequency discrimination demodulation is: ； in, is the frequency discrimination sensitivity.

6. The mid-range wireless transmission method according to claim 5, wherein: In step S33, the specific steps of clock synchronization are: S33.1: Collect signals at three time points, ； in, is the bit period, For the Sampling time Calculate the lead-lag voltage difference, ； Perform cumulative averaging, ； S33.2: Perform symbol check, ； ； S33.3: Update the phase of the sampling clock. 。

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