Self-adaptive coding and decoding system and method based on BPSK wireless data transmission

Abstract

The invention discloses a self-adaptive coding and decoding system and method based on BPSK wireless data transmission. The method comprises the steps of self-adaptive coding, data modulation and transmission, data receiving and demodulation and self-adaptive decoding. The adaptive coding dynamically adjusts the coding period according to the data change, and reduces the phase flip energy consumption; an E-class amplifier is adopted for efficient data modulation, and rapid phase modulation is achieved by adjusting a resonant circuit; a receiving end utilizes a phase-locked loop and a comparator to accurately track carrier phase change to realize data demodulation; and the self-adaptive decoder recovers the original data by using the initially demodulated data overturning signal. Through simulation and actual tests, the average transmission rate of 3.87 Mbps (continuous flipping bit stream) and 6.99 Mbps (random bit stream) is respectively realized under the carrier frequency of 13.56 MHz, the average transmission rate of 5.73 Mbps is achieved based on the random bit stream in the actual test, and the method is suitable for various wireless communication systems needing efficient and stable data transmission and has wide application prospects. Wide application prospects and important technical values are realized.

Description

[Technical field]

[0001] The present invention belongs to the field of data transmission, and in particular, relates to an adaptive coding and decoding system and method based on binary phase-shift keying (BPSK) wireless data transmission. [Background technology]

[0002] With the improvement of health awareness, the problem of visual and hearing impairment is becoming increasingly serious worldwide, and implantable medical devices provide patients with new treatment options. Devices such as cochlear implants, retinal prostheses, and brain-computer interfaces collect environmental data outside the body and transmit it to the internal system, achieving dynamic and real-time perception of environmental conditions to help patients live a normal life. However, with the increasing complexity of the functions of these devices and the continuous improvement of user needs, more stringent requirements are placed on the speed and efficiency of wireless data transmission. Especially in the field of implantable medical devices, efficient and stable near-field wireless data transmission technology has become a hot topic for domestic and foreign scientific research institutions, enterprises, and universities to explore.

[0003] Currently, amplitude-shift keying (ASK), frequency-shift keying (FSK) and phase-shift keying (PSK) are widely used data modulation methods, which transmit data by modulating the amplitude, frequency and phase of the carrier signal respectively. Although ASK is simple and easy to demodulate, it is easily interfered by changes in coil distance and external magnetic field, and the change in carrier amplitude caused by the modulation process also greatly affects the synchronous transmission of energy. FSK modulation can resist external interference, but this comes at the cost of consuming more spectrum resources, resulting in limited data transmission rate. PSK is not affected by carrier amplitude changes and occupies a narrower spectrum bandwidth, and has great potential to achieve high data rates and high energy efficiency. In implantable medical devices, binary phase-shift keying (BPSK) with a significant 180° phase change is widely used, which can simply and efficiently achieve data demodulation through a phase-locked loop-based demodulator. However, even for the easiest-to-demodulate BPSK scheme, the data transmission rate is still limited by the demodulator. Specifically, the rapid change of the carrier phase causes the demodulator to experience a long period of unlocking and relocking. This inherent defect greatly limits the data transmission capacity of BPSK. Although some studies have attempted to shorten the demodulator's relocking establishment time through digital-assisted technology, this effort has not fundamentally solved the bottleneck problem of BPSK's data transmission rate. In practical applications, the data transmission rate of BPSK is often limited to about 1 / 6 of the carrier frequency. This limitation seriously hinders the further improvement of the data transmission speed and efficiency of implantable medical devices. [Summary of the invention]

[0004] The present invention aims at the deficiencies existing in the prior art and provides an adaptive coding and decoding method based on BPSK wireless data transmission. By intelligently adjusting the coding period and combining the efficient Class E amplifier modulation and demodulation technology, the bottleneck problem of the demodulator limiting the data transmission rate is solved.

[0005] The technical solution of the present invention is as follows:

[0006] An adaptive coding and decoding system based on BPSK wireless data transmission, characterized in that it includes:

[0007] The data adaptive encoder is used to dynamically adjust the encoding period for encoding according to the data to be transmitted, wherein when the data transmitted in this round is different from the data transmitted in the previous round, the encoding is performed using the T1 encoding period; when the data transmitted in this round is the same as the data transmitted in the previous round, the encoding is performed using the T2 encoding period, and T1>T2;

[0008] The modulator modulates the data based on a Class E amplifier and transmits it wirelessly via a near-field inductive coupling link;

[0009] A demodulator, for receiving and demodulating data transmitted via a near-field inductive coupling link, and identifying changes in the transmitted data by comparing phase changes between a carrier signal and its own feedback signal;

[0010] The data adaptive decoder is used to perform adaptive decoding according to the demodulated data to restore the original data, wherein when a data change is identified, the decoder waits N cycles to decode the changed data, and the value of N corresponds to the setting of the adaptive encoder.

[0011] Furthermore, the data adaptive encoder is implemented by a state machine, which includes five states: S0 starting reset state, S1 reading data to be transmitted state, S2 judging data state, S3 completing phase flip state, and S4 waiting N cycle state.

[0012] Furthermore, the modulator generates two resonant frequencies by controlling the input voltage Vg of the class E amplifier, and then modulates and transmits data through the resonant loop and the inductive coupling link.

[0013] Furthermore, when Vg of the class E amplifier is high, Cp in the resonant circuit is short-circuited to form a series LC resonator; when Vg is low, the resonant circuit becomes a series LCC resonator, and two different resonant frequencies are generated by controlling the high and low levels of Vg.

[0014] Furthermore, the demodulator tracks the carrier signal using a phase-locked loop, and samples and compares the carrier signal with its own feedback signal at the rising edge of the double frequency clock output by the phase-locked loop, thereby identifying changes in the transmission data.

[0015] Furthermore, the data adaptive decoder is implemented by a state machine, which is driven by the falling edge of the double frequency clock output by the phase-locked loop, and determines whether the data has changed according to the change of the demodulated Data1 signal, and decodes accordingly.

[0016] Furthermore, the T1 coding period includes at least 3.5 carrier cycles, and the T2 coding period is 1 carrier cycle.

[0017] Furthermore, the value of N is set according to actual application requirements to ensure that the decoder has enough time to stabilize and correctly decode the changed data.

[0018] Second, the present invention also provides an adaptive coding and decoding method based on BPSK wireless data transmission, which is characterized in that it includes the following steps:

[0019] Step 1) Adaptive encoding of the data to be transmitted is performed, and the adaptive encoding dynamically adjusts the encoding period according to whether the currently transmitted data is the same as the data transmitted in the previous round:

[0020] When the data is different, the phase is flipped and the T1 encoding cycle is used;

[0021] When the data is the same, no phase flip is performed, and the T2 transmission coding cycle is used, and T1>T2;

[0022] Step 2) data modulation and transmission: This is achieved by using a class E amplifier, by setting the capacitance and inductance parameters in the resonant circuit so that when the phase is switched, the resonant current phase changes by 360° within 1.5 cycles, achieving a 180° phase flip of the carrier signal, and operating at a carrier frequency of 13.56 MHz;

[0023] Step 3) Receive and demodulate data: The receiving end converts the carrier signal into a square wave signal through a comparator and injects it into a phase-locked loop as a reference clock. The phase-locked loop is used to track the carrier signal to locate the phase change. The demodulator uses the rising edge of the double frequency clock output by the phase-locked loop as the sampling point, compares the phase difference between the carrier signal and its own feedback signal, identifies the change of the transmitted data, and flips the Data1 signal at the rising edge of the double frequency clock output by the phase-locked loop to complete the preliminary demodulation of the data;

[0024] Step 4) Adaptive decoding of the encoded data: The demodulated signal Data1 containing the transmission data change information is decoded by the state machine of the adaptive decoder, which is driven by the falling edge of the double frequency clock output by the phase-locked loop. During the decoding process, the Data1 signal is sampled and judged in the D1 and D2 states. If the sampled value is the same as the previous moment, it indicates that the data has not changed. The decoder returns to the D1 state to decode the next bit of data. If the sampled value is different from the previous moment, it indicates that the data has changed. The decoder enters the D3 state and waits N cycles to decode the changed data. Finally, the real data transmitted is decoded. The value of N is set according to the actual application requirements and corresponds to the setting of the adaptive encoder.

[0025] Compared with the prior art, the present invention has the following gain effects:

[0026] 1) The present invention introduces adaptive coding technology into the BPSK system, and dynamically adjusts the coding period according to whether the currently transmitted data is the same as the data transmitted in the previous round. It breaks through the limitation of the demodulator on the overall rate in the traditional BPSK transmission scheme, and the system as a whole can transmit data at a dynamic rate of "(1~N / 2) carrier / bit", which exceeds the "(N / 2) carrier / bit" limit rate of the traditional BPSK. At the same time, by designing a state machine with five states (S0, S1, S2, S3, S4), precise control of the adaptive encoder is achieved. The design of the state machine enables the encoder to automatically select the coding period according to different data states, and accurately complete the phase flip or keep the phase unchanged.

[0027] 2) Data modulation is performed using a Class E amplifier, which has the highest theoretical energy transfer efficiency and can quickly adjust the phase. By adjusting the capacitance and inductance values ​​in the resonant circuit, the resonant current phase changes by 360° within 1.5 cycles when the Vg phase is switched (i.e., the 180° phase flip of the carrier signal), which optimizes the phase flip process and reduces phase error and distortion.

[0028] 3) The demodulator uses the rising edge of the doubled frequency clock output by the phase-locked loop as the sampling point, compares the phase of the carrier signal with its own feedback signal, and thus accurately identifies the change of the data, which not only improves the accuracy of data transmission, but also enhances the anti-interference ability of the system. Adaptive decoding is performed using the Data1 signal containing the transmission data change information. By designing a state machine with four states (D0, D1, D2, D3), the present invention realizes accurate decoding of the received signal. During the decoding process, the present invention automatically selects the decoding path and waiting period according to the value and change state of the Data1 signal, thereby accurately restoring the original data. This adaptive decoding method not only improves the reliability of data transmission, but also reduces the bit error rate.

[0029] 4) Only one adaptive encoder and one adaptive decoder are needed, both of which are composed of simple state machines, with extremely low power consumption and obvious rate improvement effect.

Brief Description of the Drawings

[0030] Figure 1 It is a working block diagram of an adaptive coding and decoding system based on BPSK wireless data transmission;

[0031] Figure 2 The schematic waveform diagram of the encoding of the adaptive encoder is shown;

[0032] Figure 3 It is the state machine implementation schematic diagram of the adaptive encoder;

[0033] Figure 4It is a system architecture diagram of an adaptive coding and decoding method based on BPSK wireless data transmission;

[0034] Figure 5 This is the state machine implementation schematic diagram of the adaptive decoder;

[0035] Figure 6 is a simulation performance result diagram of an embodiment of an adaptive coding and decoding method;

[0036] Figure 7 This is a diagram showing the actual chip performance results of an embodiment of the adaptive coding and decoding method. [Specific implementation method]

[0037] The exemplary embodiments of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present invention. It should be noted that, for those of ordinary skill in the art, several variations and improvements can also be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. In the accompanying drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity of the present invention.

[0038] The present invention first adaptively encodes the data stream to be transmitted at the transmitting end, and wirelessly transmits it through a near-field inductive coupling link, and finally the data stream is adaptively decoded at the receiving end. This method breaks the limitation of the demodulator on the overall data transmission rate in the traditional BPSK transmission scheme, and achieves a significant rate improvement with minimal resource overhead.

[0039] Figure 1 The system working block diagram of the adaptive coding and decoding method proposed in the present invention is shown, which consists of five modules: data adaptive encoder, modulator, near-field inductive coupling link, demodulator, and data adaptive decoder. Data transmission mainly includes the following steps:

[0040] (1) Data adaptive coding:

[0041] The data to be transmitted is first encoded by the adaptive encoder, and the encoding waveform is as follows: Figure 2 As shown. Adaptive coding will use a variable coding cycle according to the data to be transmitted. When the data transmitted in this round is different from the previous round, the phase needs to be flipped. In order to adapt to the demodulator's establishment and stabilization time, a long T1 coding cycle ( Figure 2 4 carrier cycles are shown); when the data transmitted in this round is the same as that in the previous round, there is no need to flip the phase, and a short T2 encoding cycle is used ( Figure 2 The above adaptive coding process can break through the limitation of demodulator stabilization time and speed up the data transmission rate. The circuit of the adaptive encoder is composed of Figure 3The simple state machine implementation shown contains five states, namely: S0, S1, S2, S3, and S4. S0 is the starting reset state of the adaptive encoder. When encoding starts, the S1 state reads a bit of data to be transmitted and makes a judgment in the S2 state. If the new data value is the same as the previous data value, it returns to the S1 state to read the next bit of data to be transmitted, and completes the short-cycle encoding of the current data (1 carrier cycle). Otherwise, the encoder enters the S3 state to complete the phase flip, and then enters the S4 state to wait for N cycles to complete the long-cycle encoding of the current changed data. N is twice the length of the long-cycle encoding, and the size of N should be set according to the actual application requirements.

[0042] (2) Data modulation and transmission:

[0043] Data modulation is done based on Class E amplifiers. Class E amplifiers not only have the highest theoretical energy transmission efficiency, but also have the ability to quickly adjust the phase. Figure 4 As shown in the figure, when Vg is high, Cp in the resonant circuit is short-circuited to form a series LC resonator; when Vg is low, the circuit becomes a series LCC resonator. Thus, Vg controls the generation of two resonant frequencies, which are expressed by formulas (1) and (2) respectively:

[0044]

[0045]

[0046] By selecting a suitable LCC value, the resonant current can follow the phase change of Vg, thereby modulating and transmitting data through the resonant loop and inductive coupling link.

[0047] (3) Data reception and demodulation:

[0048] The system converts the carrier signal into a square wave through a comparator, and uses a phase-locked loop to track the carrier to locate phase changes. The demodulator samples and compares the carrier signal with its own feedback signal at the rising edge of the doubled frequency clock output by the phase-locked loop. When the transmitted data changes, the phase of the carrier signal changes. At this time, the phase of the carrier signal flips while the phase of the feedback signal remains unchanged, so the change of the transmitted data can be identified. Figure 4 The Data1 signal in the data is used to complete the preliminary demodulation of the data.

[0049] (4) Data adaptive decoding:

[0050] The demodulated Data1 signal only contains the change information of the transmitted data. To obtain the correct data transmitted, adaptive decoding is required. The adaptive decoder is also implemented by a simple state machine, such as Figure 6As shown, it is driven by the falling edge of the double frequency clock output by the phase-locked loop. The operation of the adaptive decoder is based on the above-mentioned preliminary demodulated Data1 signal (Data1 flips on the rising edge of the double frequency clock output by the phase-locked loop). When the decoder is working, Data1 is sampled and judged in the D1 and D2 states respectively. If the sampling value at this moment is the same as the previous moment, indicating that the data has not changed, the decoder returns to D1 to decode the next bit of data. Otherwise, it indicates that the data has changed, it enters the D3 state, and waits N cycles to decode the changed data. The value of N corresponds to the setting of the adaptive encoder.

[0051] like Figure 4 As shown, the adaptive coding and decoding method based on BPSK wireless data transmission provided in this embodiment includes the following steps:

[0052] (1) Adaptive encoding of the data to be transmitted. Adaptive encoding uses a variable encoding cycle according to the actual data to be transmitted. When the data transmitted in this round is different from that in the previous round, the phase needs to be flipped and a long encoding cycle of 3.5 is used; when the data transmitted in this round is the same as that in the previous round, the phase does not need to be flipped and a short encoding cycle of 1 is used. Accordingly, when designing the circuit, the counting cycle of the adaptive encoder state machine is set to 7, as shown in Figure 3 As shown. During encoding, the S1 state reads one bit of data to be transmitted and makes a judgment in the S2 state. If the new data value is the same as the previous data value, the S1 state is returned to read the next bit of data to be transmitted, and one cycle of encoding of the current data is completed at the same time. Otherwise, the encoder enters the S3 state to complete the phase flip, and then enters the S4 state to wait for 7 cycles to complete the 3.5 cycle encoding of the current changed data.

[0053] (2) Data modulation and transmission. Data modulation is done based on the Class E amplifier. The Class E amplifier not only has the highest theoretical energy transmission efficiency, but also has the ability to quickly adjust the phase. Figure 4 As shown in the figure, when Vg is high, Cp in the resonant circuit is short-circuited to form a series LC resonator; when Vg is low, the circuit becomes a series LCC resonator. By setting Cs = 102.3pF, Cp = 12.8pF, Cr = 68.8pF, L1 = 3.029μH, and L2 = 2μH, when Vg is switched in phase, the resonant current phase changes by 360° within 1.5 cycles, and the carrier signal is flipped by 180°. The overall system operates at a 13.56MHz carrier.

[0054] (3) Receive and demodulate data. The receiving system first converts the carrier signal into a square wave through a comparator, and injects this signal into a phase-locked loop as a reference clock. The phase-locked loop is used to track the carrier to locate phase changes. The demodulator samples and compares the carrier signal with its own feedback signal at the rising edge of the double-frequency clock output by the phase-locked loop. When the transmitted data changes, the phase of the carrier signal changes. At this time, the phase of the carrier signal is reversed while the phase of the feedback signal itself remains unchanged, so the change in the transmitted data can be identified. Finally, the Data1 signal is flipped at the rising edge of the double-frequency clock output by the phase-locked loop to complete the preliminary demodulation of the data.

[0055] (4) Perform adaptive decoding of the encoded data. Adaptive decoding is performed using the Data1 signal containing information about changes in the transmitted data. The state machine of the adaptive decoder is driven by the falling edge of the double-frequency clock output by the phase-locked loop. When the decoder is working, Data1 is sampled and judged in the D1 and D2 states respectively. If the sampled value at this moment is the same as the previous moment, indicating that the data has not changed, the decoder returns to D1 to decode the next bit of data. Otherwise, indicating that the data has changed, it enters the D3 state and waits for 7 cycles to decode the changed data. In this way, the real data transmitted can be finally decoded. Figure 6 The simulation results of the system data transmission of this embodiment are shown, including two cases of data continuous flip bit stream and random bit stream, and the average rates of 3.87Mbps and 6.99Mbps are achieved respectively at a carrier frequency of 13.56MHz. Figure 7 The actual test results of the chip of this embodiment after tape-out are shown. Based on the carrier frequency of 13.56 MHz, an average transmission rate of 5.73 Mbps is achieved under random bit stream.

[0056] Those skilled in the art will appreciate that all or part of the steps to implement the above embodiments may be accomplished by hardware, or may be accomplished by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, wherein the storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0057] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various deformations or modifications within the scope of the claims, which does not affect the essential content of the present invention. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and supplements can be made, and these improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. An adaptive coding and decoding system based on BPSK wireless data transmission, characterized in that: include: The data adaptive encoder is used to dynamically adjust the encoding period for encoding according to the data to be transmitted, wherein when the data transmitted in this round is different from the data transmitted in the previous round, the encoding is performed using the T1 encoding period; when the data transmitted in this round is the same as the data transmitted in the previous round, the encoding is performed using the T2 encoding period, and T1>T2; The modulator modulates the data based on a Class E amplifier and transmits it wirelessly via a near-field inductive coupling link; A demodulator, for receiving and demodulating data transmitted via a near-field inductive coupling link, and identifying changes in the transmitted data by comparing phase changes between a carrier signal and its own feedback signal; The data adaptive decoder is used to perform adaptive decoding according to the demodulated data to restore the original data, wherein when a data change is identified, the decoder waits N cycles to decode the changed data, and the value of N corresponds to the setting of the adaptive encoder.

2. The adaptive coding and decoding system based on BPSK wireless data transmission according to claim 1, characterized in that: The data adaptive encoder is implemented by a state machine, which includes five states: S0 starting reset state, S1 reading data to be transmitted state, S2 judging data state, S3 completing phase flip state, and S4 waiting for N cycles state.

3. The adaptive coding and decoding system based on BPSK wireless data transmission according to claim 1, characterized in that: The modulator generates two resonant frequencies by controlling the input voltage Vg of the class E amplifier, and then modulates and transmits data through a resonant loop and an inductive coupling link.

4. The adaptive coding and decoding system based on BPSK wireless data transmission according to claim 3 is characterized in that: When Vg is high, the Cp in the resonant circuit of the class E amplifier is short-circuited to form a series LC resonator; when Vg is low, the resonant circuit becomes a series LCC resonator, and two different resonant frequencies are generated by controlling the high and low levels of Vg.

5. The adaptive coding and decoding system based on BPSK wireless data transmission according to claim 1, characterized in that: The demodulator tracks the carrier signal by using a phase-locked loop, and samples and compares the carrier signal with its own feedback signal at the rising edge of the double frequency clock output by the phase-locked loop, thereby identifying the change of the transmission data.

6. The adaptive coding and decoding system based on BPSK wireless data transmission according to claim 1, characterized in that: The data adaptive decoder is implemented by a state machine, which is driven by the falling edge of the double frequency clock output by the phase-locked loop. It determines whether the transmission data has changed according to the change of the demodulated Data1 signal, and decodes accordingly.

7. The adaptive coding and decoding system based on BPSK wireless data transmission according to any one of claims 1 to 6, characterized in that: The T1 coding period includes at least 2 carrier cycles, and the T2 coding period is 1 carrier cycle.

8. The adaptive coding and decoding system based on BPSK wireless data transmission according to any one of claims 1 to 6, characterized in that: The value of N is set according to actual application requirements to ensure that the decoder has enough time to stabilize and correctly decode the changed data.

9. An adaptive coding and decoding method based on BPSK wireless data transmission, characterized in that: The following steps are involved: Step 1) Adaptive encoding of the data to be transmitted is performed, and the adaptive encoding dynamically adjusts the encoding period according to whether the currently transmitted data is the same as the data transmitted in the previous round: When the data is different, the phase is flipped and the T1 encoding cycle is used; When the data is the same, no phase flip is performed, and the T2 transmission coding cycle is used, and T1>T2; Step 2) data modulation and transmission: This is achieved by using a class E amplifier, by setting the capacitance and inductance parameters in the resonant circuit so that when the phase is switched, the resonant current phase changes by 360° within 1.5 cycles, achieving a 180° phase flip of the carrier signal, and operating at a carrier frequency of 13.56 MHz; Step 3) Receive and demodulate data: The receiving end converts the carrier signal into a square wave signal through a comparator and injects it into a phase-locked loop as a reference clock. The phase-locked loop is used to track the carrier signal to locate the phase change. The demodulator uses the rising edge of the double frequency clock output by the phase-locked loop as the sampling point, compares the phase difference between the carrier signal and its own feedback signal, identifies the change of the transmitted data, and flips the Data1 signal at the rising edge of the double frequency clock output by the phase-locked loop to complete the preliminary demodulation of the data; Step 4) Adaptive decoding of the encoded data: The demodulated signal Data1 containing the transmission data change information is decoded by the state machine of the adaptive decoder, which is driven by the falling edge of the double frequency clock output by the phase-locked loop. During the decoding process, the Data1 signal is sampled and judged in the D1 and D2 states. If the sampled value is the same as the previous moment, it indicates that the data has not changed. The decoder returns to the D1 state to decode the next bit of data. If the sampled value is different from the previous moment, it indicates that the data has changed. The decoder enters the D3 state and waits N cycles to decode the changed data. Finally, the real data transmitted is decoded. The value of N is set according to the actual application requirements and corresponds to the setting of the adaptive encoder.

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