CN113098556B - Data modulation negotiation method, system and terminal - Google Patents
Data modulation negotiation method, system and terminal Download PDFInfo
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- H—ELECTRICITY
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
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- H04L1/0047—Decoding adapted to other signal detection operation
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- H—ELECTRICITY
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- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
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Abstract
The invention provides a data modulation negotiation method, a system and a terminal, which combine a linear frequency modulation technology with a direct sequence spread spectrum technology, and the system can correctly demodulate at a low signal-to-noise ratio, has large link budget and strong anti-interference capability, ensures higher reliability under the condition of lower signal-to-noise ratio, and has the characteristics of high link budget and low signal-to-noise ratio demodulation. The method comprises the steps of obtaining a spread spectrum factor through a modulation negotiation process between a sending end and a receiving end, sending and receiving data through a mode of combining a linear modulation spread spectrum technology and a direct sequence spread spectrum technology, and increasing the reliability of the system by using a method of increasing the direct sequence spread spectrum factor after the linear modulation spread spectrum and the direct sequence spread spectrum are combined.
Description
Technical Field
The present invention belongs to the field of communication technology, and in particular, to a data modulation negotiation method, system, and terminal.
Background
At present, the communication technology mostly adopts 400M, 800M and power line coupling communication modes, and the power line carrier coupling mode is a mode that a power line carrier signal is connected with a power line through a coupling device.
The antenna coupling is adopted between the carrier machine and the power line at first, and the capacitor coupling is adopted later, so that the carrier machine and the power line are used for many years. For example, the connection mode of the conjunction device is classified into a ground coupling mode and a conjunction mode. Although it is relatively economical in equipment. And more channels can be organized in a line, but the transmission attenuation is greater. When the coupled phase has short-circuit ground fault, the channel reliability is poor. The phase vivid mode requires two package switches and two line wave traps at the coupling point. Compared with the phase-to-ground reporting method, although the transmission attenuation is doubled, the reliability is higher when the line fails, and the signaling interference is smaller. In order to solve the contradiction of bright transmission and large attenuation of long-distance and high-voltage power line carrier channels, the mutual accident party is adopted at home and abroad to ensure the reliability of important channel transmission. For double-force lines on the same pole, one wire of each loop can be used to form a phase-tumbler so that even if one loop is not powered and grounded, the channel will not increase the number of hairs of the interrupter to be in Po-Xiang-Conjue. The conventional communication scheme has the advantages of low link budget, poor interference resistance and short transmission distance.
In the prior art, the existing Lora scheme adopts a coding mode of Chirp modulation and hamming codes, wherein the hamming codes can only realize error correction of inversion of 1-bit code elements, the interference resistance of Chirp modulation and Turbo codes is not high, and the required bandwidth is exponentially increased when each traditional linear modulation spreading factor is increased by one bit. I.e. the chip time required for an increase of the spreading factor by one bit or the modulation bandwidth required. Therefore, when the communication system has a definite limitation on the frame length or bandwidth, the use of the chirp spread spectrum method may cause a waste of resources in time or frequency. Direct sequence spread spectrum communication can increase the spread spectrum length according to the link budget requirement, but has poor interference resistance.
Therefore, obtaining a communication modulation negotiation method with high interference rejection and reliability at low snr becomes an urgent problem in the art.
Disclosure of Invention
In view of the above problem, the present invention provides a data modulation negotiation method, where the method includes:
the sending end sends a lead code to the receiving end;
the receiving end calculates the error rate according to the lead code, obtains a spread spectrum factor according to the error rate table look-up, and sends a guidance numerical value corresponding to the spread spectrum factor to the sending end;
the sending end receives the guide value and obtains a spread spectrum factor according to the table lookup of the guide value;
and the transmitting end modulates the application data by using the spreading parameters corresponding to the spreading factors.
Further, the spreading factor includes a linear modulation spreading factor and a direct sequence spreading factor.
Further, the transmitting end receives the index value after the end of the protection time slot.
Further, the step of modulating the application data by the transmitting end using the spreading parameters corresponding to the spreading factors includes the following steps:
adding cyclic redundancy check to the application data, and using channel coding to the added application data;
performing direct sequence spread spectrum on the application data after channel coding;
performing frame mapping on the application data subjected to direct sequence spread spectrum;
performing linear modulation spread spectrum serial-parallel conversion on the application data after frame mapping;
and modulating the application data after serial-parallel conversion by using the linear modulation spread spectrum factor obtained by table lookup, and sending the application data in an analog mode.
The invention also provides a data modulation and transmission method, which comprises the following steps:
the sending end sends a lead code to the receiving end;
the sending end receives a feedback guide value sent by the receiving end and looks up a table according to the guide value to obtain a spread spectrum factor;
and the transmitting end modulates the application data by using the spreading parameters corresponding to the spreading factors and transmits the application data.
The data modulation and transmission method further comprises the following step of modulating the application data by the transmitting end by using the spreading parameters corresponding to the spreading factors:
adding cyclic redundancy check to the application data, and using channel coding to the added application data;
performing direct sequence spread spectrum on the application data after channel coding;
performing frame mapping on the application data subjected to direct sequence spread spectrum;
performing linear modulation spread spectrum serial-parallel conversion on the application data after frame mapping;
and modulating the application data after serial-parallel conversion by using the linear modulation spread spectrum factor obtained by table lookup, and sending the application data in an analog mode.
Further, the transmitting end receives the index value after the end of the protection time slot.
The invention also provides a data modulation receiving method, which comprises the following steps:
a receiving end receives a lead code sent by a sending end;
the receiving end calculates the error rate according to the lead code, obtains a spread spectrum factor according to the error rate table look-up, and sends a guidance numerical value corresponding to the spread spectrum factor to the sending end;
and the receiving end receives the application data according to the spreading parameters corresponding to the spreading factors.
Further, in the step of receiving, at the receiving end, the application data according to the spreading parameter corresponding to the spreading factor, the method specifically includes:
carrying out linear modulation and demodulation on the received application data;
performing serial-parallel conversion on the demodulated application data;
despreading the application data after the series-parallel conversion by using a spreading factor of direct sequence spread spectrum;
decoding the despread data;
and performing cyclic redundancy check on the decoded application data, if the check is passed, transmitting the demodulated application data to a data application layer, otherwise, discarding the data.
The present invention also provides a data modulation negotiation system, which comprises: a transmitting end and a receiving end, wherein:
the sending end is used for sending the lead code to the receiving end;
the receiving end is used for calculating the error rate according to the lead code, looking up a table according to the error rate to obtain a spreading factor, and sending a guidance numerical value corresponding to the spreading factor to the sending end;
the sending end is used for receiving the guide value and looking up a table according to the guide value to obtain a spread spectrum factor;
and the sending end is used for modulating the application data by using the spreading parameters corresponding to the spreading factors.
The present invention also provides a terminal, including:
modulation unit, lead code sending unit, spread spectrum unit, receive feedback unit, look up table unit, lead code receiving unit, demodulation unit, bit error rate computational element, feedback unit, despreading unit, wherein:
the modulation unit is used for modulating the lead code; the lead code sending unit is used for sending the modulated lead code to the lead code receiving unit; the receiving feedback unit is used for receiving the index value; the table look-up unit is used for looking up a table to obtain a spreading factor; the spread spectrum unit is used for modulating and spreading the application data;
the lead code receiving unit is used for receiving a lead code; the demodulation unit is used for demodulating the lead code; the error rate calculation unit is used for calculating an error rate; the feedback unit is used for sending a guide numerical value to the sending end; the despreading unit is used for despreading the application data.
Furthermore, the terminal also comprises a cyclic redundancy check unit and a serial-parallel conversion unit;
the cyclic redundancy check unit is used for performing cyclic redundancy check on the transmitted/received application data;
the serial-parallel conversion unit is used for realizing serial and parallel conversion of application data in a channel.
Further, the terminal also comprises a channel coding unit and a data mapper;
the channel coding unit is used for carrying out channel coding on application data;
the data mapper is used for mapping the input end application data to the frame of the receiving end application data.
Further, the terminal further includes a channel decoding unit, and the channel decoding unit is configured to perform channel decoding on the application data.
The invention also provides a data frame sending/receiving method, which comprises the following steps:
sending/receiving a data frame carrying data, wherein the data frame consists of a lead code time slot, a protection time slot, a serial number time slot and an application data time slot;
transmitting/receiving a preamble in the preamble slot;
and transmitting/receiving index values with spread spectrum factor modulation table symbols in the sequence number time slots.
The data modulation negotiation method, the system and the terminal combine the linear frequency modulation technology and the direct sequence spread spectrum technology, the system can correctly demodulate at a low signal-to-noise ratio, the link budget of the system is large, the anti-interference capability is strong, the higher reliability is ensured under the condition of a lower signal-to-noise ratio, and the data modulation negotiation method, the system and the terminal have the characteristics of high link budget and low signal-to-noise ratio demodulation. The method comprises the steps of obtaining a spread spectrum factor through a modulation negotiation process between a sending end and a receiving end, sending and receiving data through a mode of combining a linear modulation spread spectrum technology and a direct sequence spread spectrum technology, and increasing the reliability of the system by using a method of increasing the direct sequence spread spectrum factor after the linear modulation spread spectrum and the direct sequence spread spectrum are combined. The direct sequence spreading factor is increased by one bit, each chip only brings the time broadening of one code element, and for a system, the spreading step size is smaller, so that the resources can be more fully utilized. The system can correctly demodulate under the condition of low signal-to-noise ratio, has large link budget and strong anti-interference capability, and ensures higher reliability under the condition of lower signal-to-noise ratio. In addition, the modulation mode of the invention is selected according to the condition of the current channel, and the modulation mode can be flexibly configured without restarting.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
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 some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a flow chart of a modulation negotiation process according to an embodiment of the present invention;
FIG. 2 is a diagram illustrating a slot structure according to an embodiment of the present invention;
FIG. 3 is a detailed flowchart of a modulation negotiation process according to an embodiment of the present invention;
fig. 4 is a flowchart of a modulation scheme at a transmitting end according to an embodiment of the present invention;
FIG. 5 is a flowchart illustrating a modulation scheme at a receiving end according to an embodiment of the present invention;
FIG. 6 is a flowchart of an application data sending process according to an embodiment of the present invention;
fig. 7 is a flowchart of an application data receiving process according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the embodiment of the present invention, the communication between heavy haul trains is taken as an example for illustration, and the communication negotiation manner without departing from the essential protection scope of the present invention is within the protection scope of the present invention. The running section of the heavy-duty train is not covered by a ground network generally, so that how to realize the real-time information interaction of the position of the heavy-duty train in a region without the coverage of communication infrastructure is realized, the reliability of point-to-point communication of the heavy-duty train is improved, and the method has important significance for improving the transport capacity and the transport capacity of the heavy-duty train and increasing the transport efficiency.
Frequency Division Multiplexing (FDM) is the Division of the total bandwidth for a transmission channel into several sub-bands (or sub-channels), each of which transmits 1 channel of signals. The total frequency width of frequency division multiplexing is required to be larger than the sum of the frequencies of all the sub-channels, and meanwhile, in order to ensure that signals transmitted in all the sub-channels do not interfere with each other, an isolation band is required to be arranged among all the sub-channels, so that all the paths of signals are ensured not to interfere with each other (one of conditions). The frequency division multiplexing technology is characterized in that signals transmitted by all sub-channels work in a parallel mode, and transmission time delay can be not considered when each path of signals is transmitted, so that the frequency division multiplexing technology is widely applied.
Fig. 1 is a flowchart of a modulation negotiation process according to an embodiment of the present invention, in fig. 1, a sending end sends a preamble to a receiving end; the receiving end calculates the error rate according to the lead code, obtains the spreading factor according to the error rate table look-up, and sends a guidance value corresponding to the spreading factor to the sending end; the transmitting end receives the guide value and looks up a table according to the guide value to obtain a spreading factor; and the transmitting end modulates the application data by using the spread spectrum parameters corresponding to the spread spectrum factors. Through the modulation negotiation process, the invention has higher reliability under the condition of low signal-to-noise ratio, and simultaneously has the characteristics of high link budget and low signal-to-noise ratio demodulation. The spread spectrum factor is obtained through the modulation negotiation process between the sending end and the receiving end, data sending and receiving are carried out through a mode of combining a linear modulation spread spectrum technology and a direct sequence spread spectrum technology, after the linear modulation spread spectrum technology and the direct sequence spread spectrum technology are combined, the reliability of the system is improved by using a method for increasing the direct sequence spread spectrum factor, the system can correctly demodulate under the condition of low signal-to-noise ratio, the link budget of the system is large, the anti-interference capability is strong, and the higher reliability is ensured under the condition of lower signal-to-noise ratio.
In order to better describe the communication negotiation manner of the present invention, an embodiment of the present invention further provides a data sending method, including: the sending end sends a lead code to the receiving end; the sending end receives a feedback guide value sent by the receiving end and looks up a table according to the guide value to obtain a spread spectrum factor; and the transmitting end modulates the application data by using the spreading parameters corresponding to the spreading factors.
The embodiment of the invention also provides a data modulation receiving method, which comprises the following steps: a receiving end receives a lead code sent by a sending end; the receiving end calculates the error rate according to the lead code, obtains the spread spectrum factor according to the error rate table look-up, and sends a guidance value corresponding to the spread spectrum factor to the sending end; and the receiving end receives the application data according to the spread spectrum parameters corresponding to the spread spectrum factors.
Illustratively, the present invention is described by taking a communication system of two vehicle-mounted radio stations as an example, and the sending-end vehicle-mounted radio station 1 uses f1Frequency point transmission, f2Frequency point receiving, receiving end vehicle station 2 uses f2Frequency point transmission, f1The frequency point receiving, transmitting and receiving are divided into two parts. The method comprises the following steps: obtaining a modulation mode according to the error rate of the lead code; step two: and transmitting the application data by using the modulation mode. In the embodiment of the present invention, the communication between two vehicle-mounted radio stations is used for example, and in the actual application process, the connection communication between two communication devices is within the protection scope of the present invention without departing from the essential content of the communication in the embodiment of the present invention.
The data transmission is realized by a frame structure, the frame structure consists of time slots, and the data transmission function is distributed by dividing different time slot structures in the frame.
FIG. 2 is a diagram illustrating a structure of a time slot according to an embodiment of the present invention, where in FIG. 2, a time slot of a transmitting end and a time slot of a receiving end are represented by f1The frequency point is, for example, as shown in part A of FIG. 2, a time slot structure of the sending end of the station 1, which isThe middle frame is composed of four sub-slots, T0 is the initial node of the sub-slot, TprFor transmitting pilot transmission time slots, TgapTo protect time slots, TindReceiving time slots, T, for sequence numbersinfoTransmitting a time slot for the application data; as shown in part B of FIG. 2, the slot structure at the receiving end of station 2 is shown, where a frame is composed of four sub-slots, T0 is the initial node of the sub-slot, TprFor receiving pilot transmission time slots, TgapTo protect time slots, TindFor transmitting time slots, T, for sequence numbersinfoA slot is received for application data.
In fig. 2, G denotes a guard slot. In the pilot transmission time slot, the sending end radio station 1 sends a series of Preamble codes (preambles) with known sequences, performs quadrature phase shift coding (QPSK) on the Preamble codes, and then sends the Preamble codes to the receiving end radio station 2. Receiving end radio station 2 receives the preamble in the preamble time slot, transmitting end radio station 2 demodulates the received preamble, calculates error rate according to the known preamble sequence and the demodulated preamble, and simultaneously obtains the spreading factor of linear modulation spread spectrum and the spreading factor of direct sequence spread spectrum according to the error rate table lookup, and forms Index numerical value (Index numerical value with spreading factor sequence number) of the modulation table symbol carrying the spreading factor;
the sending pilot frequency sending time slot is followed by a protection time slot, and the protection time slot ensures that the data links of the sending end and the receiving end do not interfere with each other and ensures the stability of the data transmission system.
The protection time slot is a serial number receiving time slot or a serial number sending time slot, the receiving end feeds back Index values to the sending end in the serial number sending time slot, and the sending end receives the Index values fed back by the sending end in the serial number receiving time slot synchronously;
and then, a data sending time slot is formed after the serial number receiving time slot, a data receiving time slot is formed after the serial number sending time slot, the sending end radio station 1 obtains a linear modulation spreading factor and a direct sequence spreading factor for modulation based on Index numerical value table lookup in the data sending time slot, sends application data, and the receiving end radio station 2 completes de-spreading and data receiving processes based on the linear modulation spreading factor (Chirp SF) and the direct sequence spreading factor (DSSS SF) obtained by table lookup.
Based on the above data sending and receiving method, the whole process is a data modulation negotiation method, and fig. 3 shows a specific flowchart of the modulation negotiation process in the embodiment of the present invention:
a sending end radio station 1 modulates and sends a lead code by using an orthogonal phase shift coding mode;
the receiving end radio station 2 demodulates the received lead code sent by the radio station 1 and calculates the error rate according to the known lead code sequence;
the receiving end radio station 2 obtains a Chirp modulated spreading factor and a direct sequence spread spreading factor according to the calculated error rate table lookup, and sends an Index value of the Index to the radio station 1, wherein the Index value is the Index value with the sequence number of the spreading factor;
a sending end radio station 1 obtains a spreading factor of linear modulation spread spectrum and a spreading factor of direct sequence spread spectrum according to a received Index numerical value table look-up;
the sending end radio station 1 modulates the application data by using the spread spectrum parameters corresponding to the spread spectrum factors obtained by table lookup, and sends the modulated application data to the receiving end radio station 2;
and the radio station 2 demodulates the application data sent by the radio station 1 according to the spread spectrum parameters obtained by table lookup, and receives the application data after demodulation.
Based on the above modulation negotiation process, the embodiment of the present invention further provides a flow chart of a modulation scheme process at the transmitting end, and as shown in fig. 4, the modulation negotiation scheme at the transmitting end is as follows:
the sending end radio station 1 uses QPSK modulation mode to modulate and send lead codes (the lead code sequences of the sending end and the receiving end are known);
after the end of the protection time slot, the sending end radio station 1 receives the serial number of the modulation mode, where the modulation mode is Chirp SF = max (maximum value of spreading factor of linear modulation spread spectrum);
a sending end radio station 1 receives the guide value, and looks up a table to obtain a spread spectrum factor modulated by Chirp and a spread spectrum factor spread by a direct sequence;
and modulating the application data by the spread spectrum parameter corresponding to the spread spectrum factor of the sending end radio station 1, and sending the application data to the radio station 2.
Based on the above modulation negotiation process, fig. 5 is a flow chart of a modulation scheme process at the receiving end according to the embodiment of the present invention, and the modulation negotiation scheme at the receiving end is as follows:
the receiving end radio station 2 demodulates the received lead code, and calculates the error rate by comparing with the known lead code sequence, wherein the modulation mode is QPSK;
the receiving end obtains a spreading factor of linear modulation spread spectrum and a direct sequence spreading factor according to the calculated error rate table lookup, and obtains a spreading factor of Chirp modulation and a spreading factor of direct sequence spread spectrum according to the error rate after the end of the protection time slot;
sending an Acknowledgement Character (ACK) with a modulation table serial number to a sending terminal radio station 1), wherein the modulation mode is Chirp SF = max;
and the receiving end is used for obtaining the spread spectrum factor of the linear modulation spread spectrum according to the calculated error rate table lookup and receiving the application data sent by the sending end radio station 1 by using the spread spectrum parameter corresponding to the direct sequence spread spectrum factor.
The process that the transmitting end transmits the application data based on the spread spectrum factor modulation spread spectrum reduces the error rate, and when the same spread spectrum multiple is used, the effect is better than that of other spread spectrum, as shown in fig. 6, the specific steps are as follows:
1.1, a sending end radio station 1 obtains application data to be sent;
1.2, adding Cyclic Redundancy Check (CRC), checking whether data transmission is wrong or not, and ensuring the correctness and the integrity of the data transmission;
1.3, 1/3Turbo channel coding is used for the application data which is processed by the CRC;
1.4, spreading the coded application data according to the direct sequence spreading factor obtained by table look-up;
1.5, performing frame mapping on the application data subjected to direct sequence spread spectrum to enable the data stream to be mapped into a receiving end frame structure from a sending end frame structure;
1.6, performing serial-parallel conversion on the data subjected to the direct sequence spread spectrum in the step 1.4 according to the linear modulation spread spectrum factor;
1.7, modulating by using a linear modulation spread spectrum factor obtained by table lookup;
1.8, sending by an analog mode.
After the sending end radio station 1 sends out the data, the receiving end radio station 2 carries out the application data receiving process synchronously, has reduced the bit error rate, when using the same spread spectrum multiple, better than other spread spectrum effects, refer to fig. 7, specifically as follows:
2.1, receiving application data sent by a sending end radio station 1, and demodulating the application data in a linear modulation spread spectrum mode;
2.2, performing serial-parallel conversion on the data subjected to linear modulation and demodulation;
2.3, using the spreading factor of direct sequence spread spectrum obtained by table look-up in the modulation negotiation process to perform despreading again on the data in the step 2.2;
2.4, Turbo decoding is carried out on the despread data;
and 2.5, performing Cyclic Redundancy Check (CRC), if the CRC passes, transmitting the demodulated application data to a data application layer, and otherwise, discarding the data.
The present invention also provides a data negotiation system, including: a transmitting end and a receiving end, wherein:
the sending end is used for sending the lead code to the receiving end;
the receiving end is used for calculating the error rate according to the lead code, looking up a table according to the error rate to obtain a spreading factor, and sending a guidance numerical value corresponding to the spreading factor to the sending end;
the sending end is used for receiving the guide value and looking up a table according to the guide value to obtain a spread spectrum factor; and the sending end is used for modulating the application data by using the spreading parameters corresponding to the spreading factors.
Further, to better describe the negotiation method of the present invention, an embodiment of the present invention further provides a terminal, including:
modulation unit, lead code sending unit, spread spectrum unit, receive feedback unit, look up table unit, lead code receiving unit, demodulation unit, bit error rate computational element, feedback unit, despreading unit, wherein:
the modulation unit is used for modulating the lead code; the lead code sending unit is used for sending the modulated lead code to the lead code receiving unit; the receiving feedback unit is used for receiving the index value; the table look-up unit is used for looking up a table to obtain a spreading factor; the spread spectrum unit is used for modulating and spreading the application data;
the lead code receiving unit is used for receiving a lead code; the demodulation unit is used for demodulating the lead code; the error rate calculation unit is used for calculating an error rate; the feedback unit is used for sending a guide numerical value to the sending end; the despreading unit is used for despreading the application data.
Furthermore, the terminal also comprises a cyclic redundancy check unit and a serial-parallel conversion unit; the cyclic redundancy check unit is used for performing cyclic redundancy check on the transmitted/received application data; the serial-parallel conversion unit is used for realizing serial and parallel conversion of application data in a channel.
Further, the terminal also comprises a channel coding unit and a data mapper; the channel coding unit is used for performing Turbo channel coding on application data; the data mapper is used for mapping the input end application data to the frame of the receiving end application data; the terminal also comprises a channel decoding unit, and the channel decoding unit is used for Turbo channel decoding of the application data.
The invention includes data transmission system and modulation negotiation system based on special time slot structure, the modulation negotiation process of the data is realized in the time slot structure, realize data transmission and modulation negotiation through sending end and receiving end, the embodiment of the invention provides a data frame sending/receiving method, including: sending/receiving a data frame carrying data, wherein the data frame consists of a lead code time slot, a protection time slot, a serial number time slot and an application data time slot; transmitting/receiving a preamble in a preamble slot; index values with spreading factor modulation table symbols are transmitted/received in the sequence number slots.
Furthermore, the data frame of the invention is composed of a lead code time slot, a protection time slot, a serial number time slot and an application data time slot in sequence.
The present invention also provides a data frame transmitting/receiving system, which includes:
a sending unit, configured to send a data frame carrying data;
the device comprises a storage unit and a processing unit, wherein the storage unit is used for storing a data frame, and the data frame comprises a lead code time slot, a protection time slot, a serial number time slot and an application data time slot. Specifically, a preamble is transmitted/received in a preamble slot; index values with spreading factor modulation table symbols are transmitted/received in the sequence number slots.
Further, the present invention provides a data frame sending method, including:
sending a data frame carrying data, wherein the data frame consists of a lead code time slot, a protection time slot, a serial number receiving time slot and an application data sending time slot;
sending a preamble in a preamble slot; index values with spreading factor modulation table symbols are received in the sequence number receive slots.
The invention also provides a data frame receiving method, which comprises the following steps:
receiving a data frame carrying data, wherein the data frame consists of a lead code time slot, a protection time slot, a serial number sending time slot and an application data receiving time slot;
receiving a preamble in a preamble slot; index values with spreading factor modulation table symbols are transmitted in the sequence number transmission slots.
Furthermore, the four sub-time slots are a lead code time slot, a protection time slot, a serial number receiving time slot and an application data sending time slot at a sending end;
the receiving end is divided into a lead code time slot, a protection time slot, a serial number sending time slot and an application data receiving time slot.
The sending and receiving of the lead code are realized in the lead code time slot;
the protection time slot can ensure that the data links of the sending end and the receiving end are not interfered with each other, and simultaneously ensure the stability of a data transmission system;
transmitting a guidance numerical value with a spread spectrum factor modulation table symbol in a sequence number transmitting time slot;
receiving a guide numerical value with a spread spectrum factor modulation table symbol in a sequence number receiving time slot;
transmitting application data in the application data transmission time slot;
application data is received in an application data reception slot.
The embodiment of the invention also provides a data frame sending system, which comprises: a sending unit, configured to send a data frame carrying data; the device comprises a storage unit and a sending unit, wherein the storage unit is used for storing a data frame, and the data frame consists of a lead code time slot, a protection time slot, a serial number receiving time slot and an application data sending time slot.
Specifically, the preamble slot is used for transmitting a preamble; the sequence number receiving time slot is used for receiving a guide numerical value with a spread spectrum factor modulation table symbol; the protection time slot is used for ensuring that data links of the sending end and the receiving end are not interfered with each other and ensuring the stability of a data transmission system; the application data transmission slot is used for transmitting application data.
The embodiment of the invention also provides a data frame receiving system, which comprises: a receiving unit, configured to receive a data frame carrying data; the device comprises a storage unit and a data processing unit, wherein the storage unit is used for storing a data frame, and the data frame comprises a lead code time slot, a protection time slot, a serial number sending time slot and an application data receiving time slot.
Specifically, the preamble slot is used for receiving a preamble; the sequence number sending time slot is used for sending a guidance numerical value with a spread spectrum factor modulation table symbol; the protection time slot is used for ensuring that data links of the sending end and the receiving end are not interfered with each other and ensuring the stability of a data transmission system; the application data receiving slot is for receiving application data.
The data modulation negotiation method, the system and the terminal combine the linear frequency modulation technology and the direct sequence spread spectrum technology, the system can correctly demodulate at a low signal-to-noise ratio, the link budget of the system is large, the anti-interference capability is strong, the higher reliability is ensured under the condition of a lower signal-to-noise ratio, and the data modulation negotiation method, the system and the terminal have the characteristics of high link budget and low signal-to-noise ratio demodulation. The method comprises the steps of obtaining a spread spectrum factor through a modulation negotiation process between a sending end and a receiving end, sending and receiving data through a mode of combining a linear modulation spread spectrum technology and a direct sequence spread spectrum technology, and increasing the reliability of the system by using a method of increasing the direct sequence spread spectrum factor after the linear modulation spread spectrum and the direct sequence spread spectrum are combined. The direct sequence spreading factor is increased by one bit, each chip only brings the time broadening of one code element, and for a system, the spreading step size is smaller, so that the resources can be more fully utilized. The system can correctly demodulate under the condition of low signal-to-noise ratio, has large link budget and strong anti-interference capability, and ensures higher reliability under the condition of lower signal-to-noise ratio. In addition, the modulation mode of the invention is selected according to the condition of the current channel, and the modulation mode can be flexibly configured without restarting.
Although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (15)
1. A data modulation negotiation method, characterized in that the method comprises:
the sending end sends a lead code to the receiving end;
the receiving end calculates the error rate according to the lead code, obtains a spread spectrum factor according to the error rate table look-up, and sends a guidance numerical value corresponding to the spread spectrum factor to the sending end;
the sending end receives the guide value and obtains a spread spectrum factor according to the table lookup of the guide value;
and the transmitting end modulates the application data by using the spreading parameters corresponding to the spreading factors.
2. The data modulation negotiation method of claim 1, wherein the spreading factor comprises a linear modulation spreading factor and a direct sequence spreading factor.
3. The data modulation negotiation method of claim 1,
and the transmitting end receives the index value after the protection time slot is finished.
4. The data modulation negotiation method of claim 1, wherein the step of modulating the application data by the transmitting end using the spreading parameters corresponding to the spreading factors comprises the steps of:
adding cyclic redundancy check to the application data, and using channel coding to the added application data;
performing direct sequence spread spectrum on the application data after channel coding;
performing frame mapping on the application data subjected to direct sequence spread spectrum;
performing linear modulation spread spectrum serial-parallel conversion on the application data after frame mapping;
and modulating the application data after serial-parallel conversion by using the linear modulation spread spectrum factor obtained by table lookup, and sending the application data in an analog mode.
5. A method for modulating and transmitting data, the method comprising:
the sending end sends a lead code to the receiving end;
the method comprises the steps that a sending end receives a feedback guide value sent by a receiving end, and a spread spectrum factor is obtained according to table lookup of the guide value, wherein the feedback guide value corresponds to the spread spectrum factor obtained by the receiving end according to the error rate calculation of a lead code;
and the transmitting end modulates the application data by using the spreading parameters corresponding to the spreading factors and transmits the application data.
6. The data modulation transmission method according to claim 5,
in the step of modulating, at the transmitting end, the application data by using the spreading parameters corresponding to the spreading factors, the method specifically includes:
adding cyclic redundancy check to the application data, and using channel coding to the added application data;
performing direct sequence spread spectrum on the application data after channel coding;
performing frame mapping on the application data subjected to direct sequence spread spectrum;
performing linear modulation spread spectrum serial-parallel conversion on the application data after frame mapping;
and modulating the application data after serial-parallel conversion by using the linear modulation spread spectrum factor obtained by table lookup, and sending the application data in an analog mode.
7. The data modulation transmission method according to claim 5,
and the transmitting end receives the index value after the protection time slot is finished.
8. A data modulation receiving method, characterized in that the method comprises:
a receiving end receives a lead code sent by a sending end;
the receiving end calculates the error rate according to the lead code, obtains a spread spectrum factor according to the error rate table look-up, and sends a guidance numerical value corresponding to the spread spectrum factor to the sending end;
and the receiving end receives the application data according to the spreading parameters corresponding to the spreading factors.
9. The data modulation receiving method according to claim 8, wherein the step of receiving, at the receiving end, the application data according to the spreading parameter corresponding to the spreading factor specifically includes:
carrying out linear modulation and demodulation on the received application data;
performing serial-parallel conversion on the demodulated application data;
despreading the application data after the series-parallel conversion by using a spreading factor of direct sequence spread spectrum;
decoding the despread data;
and performing cyclic redundancy check on the decoded application data, if the check is passed, transmitting the demodulated application data to a data application layer, otherwise, discarding the data.
10. A data modulation negotiation system, the system comprising: a transmitting end and a receiving end, wherein:
the sending end is used for sending the lead code to the receiving end;
the receiving end is used for calculating the error rate according to the lead code, looking up a table according to the error rate to obtain a spreading factor, and sending a guidance numerical value corresponding to the spreading factor to the sending end;
the sending end is used for receiving the guide value and looking up a table according to the guide value to obtain a spread spectrum factor;
and the sending end is used for modulating the application data by using the spreading parameters corresponding to the spreading factors.
11. A terminal, characterized in that the terminal comprises:
modulation unit, lead code sending unit, spread spectrum unit, receive feedback unit, look up table unit, lead code receiving unit, demodulation unit, bit error rate computational element, feedback unit, despreading unit, wherein:
the modulation unit is used for modulating the lead code; the lead code sending unit is used for sending the modulated lead code to the lead code receiving unit; the receiving feedback unit is used for receiving the index value; the table look-up unit is used for looking up a table to obtain a spreading factor; the spread spectrum unit is used for modulating and spreading the application data;
the lead code receiving unit is used for receiving a lead code; the demodulation unit is used for demodulating the lead code; the error rate calculation unit is used for calculating an error rate; the feedback unit is used for sending a guide numerical value to the sending end; the de-spreading unit is used for de-spreading the application data;
the error rate calculation unit calculates an error rate according to the lead code received by the lead code receiving unit, the table look-up unit is used for looking up a table according to the error rate to obtain a spreading factor, and the feedback unit sends a guidance numerical value corresponding to the spreading factor;
the receiving feedback unit is used for receiving the guide numerical value, the table look-up unit is used for looking up a table according to the guide numerical value to obtain a spreading factor, the spreading unit modulates and transmits application data by using spreading parameters corresponding to the spreading factor, and the despreading unit is used for despreading the application data received by the spreading parameters corresponding to the spreading factor.
12. The terminal of claim 11, wherein the terminal further comprises a cyclic redundancy check unit, a serial-to-parallel conversion unit;
the cyclic redundancy check unit is used for performing cyclic redundancy check on the transmitted/received application data;
the serial-parallel conversion unit is used for realizing serial and parallel conversion of application data in a channel.
13. The terminal of claim 11, wherein the terminal further comprises a channel coding unit, a data mapper;
the channel coding unit is used for carrying out channel coding on application data;
the data mapper is configured to map the application data onto a frame of the application data.
14. The terminal of claim 11,
the terminal also comprises a channel decoding unit, and the channel decoding unit is used for carrying out channel decoding on the application data.
15. A data frame transmission/reception method, comprising:
sending/receiving a data frame carrying data, wherein the data frame consists of a lead code time slot, a protection time slot, a serial number time slot and an application data time slot;
transmitting/receiving a preamble in the preamble slot;
and transmitting/receiving index values with spread spectrum factor modulation table symbols in the sequence number time slots.
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