WO2020258410A1

WO2020258410A1 - Photoelectric hybrid single-frequency network broadcasting method and system

Info

Publication number: WO2020258410A1
Application number: PCT/CN2019/096570
Authority: WO
Inventors: 杨昉; 王甫镔; 宋健; 潘长勇; 王劲涛; 张超; 彭克武
Original assignee: 清华大学
Priority date: 2019-06-28
Filing date: 2019-07-18
Publication date: 2020-12-30
Also published as: CN110336608A

Abstract

Disclosed are a photoelectric hybrid single-frequency network broadcasting method and system, the method comprising the following steps: a control center simultaneously sending a data flow and a control signal to a radio transmitter and a visible light transmitter, and using a single-frequency network adapter to ensure synchronization between the control center and the transmitters, digital signal processing processes of the radio transmitter and the visible light transmitter before digital/analog conversion being consistent, and afterwards, different transmitters respectively performing processing according to the physical characteristics different signals so as to obtain and send radio signals and visible light signals; the receiver may receive radio signals or visible light signals separately, and may also simultaneously receive the two kinds of signals and perform different means of superimposition. The present method implements equivalent hybrid single-frequency network system architecture, saves frequency resources, improves the spectrum utilization rate, and enables the receiver to receive and merge radio signals and visible light signals, so as to achieve seamless connection of indoor and outdoor signal coverage and seamless switching of signal reception.

Description

Photoelectric hybrid single frequency network broadcasting method and system

Cross references to related applications

This application claims the priority of the Chinese Patent Application No. “201910576029.7” filed by Tsinghua University on June 28, 2019 with the title of “Optical Hybrid Single Frequency Network Broadcasting Method and System”.

Technical field

The present invention relates to the field of communication technology, in particular to a photoelectric hybrid single frequency network broadcasting method and system.

Background technique

As one of the most important sources of information and entertainment in people’s daily life, the radio broadcasting system represented by the digital television terrestrial broadcasting (DTTB) system has been widely popularized in recent decades, and radio communication technologies and standards have also been rapidly developed. development of. Compared with analog TV, digital TV has the characteristics of strong anti-interference ability, high spectrum efficiency, support for multiple multiplexing methods, and support for multiple value-added services. Compared with various radio broadcasting systems such as satellite systems and cable networks, the DTTB system based on terrestrial TV transmission towers can adapt to a more flexible and complex receiving environment. It is recognized as the most important digital TV broadcasting system and has the widest audience. .

Currently, indoor signal transmission needs are much greater than outdoor environments, but it is difficult for radio systems with wide area coverage to achieve high-quality coverage of indoor environments. This is not only because radio signals from outdoors will be shielded by the outer walls of the building, but also because the relatively dense indoor scatterers form a more complex multipath environment. In this case, the indoor wireless channel needs to be measured and modeled, and additional techniques are needed to compensate for the transmission loss of indoor radio signals in order to improve the indoor coverage performance of a radio system with wide area coverage. To think about it from another angle, you can use a wireless communication system suitable for indoor coverage to combine it with a wide-area coverage radio system to achieve wider and deeper coverage. The issues that need to be considered are the differences between different systems. Compatibility and stability of switching.

With the rapid development of light-emitting diodes (LEDs), visible light communication (VLC), as a new type of wireless optical communication technology, has gradually received extensive attention and research from academia and industry in recent years. VLC provides huge system capacity and abundant spectrum bandwidth, avoiding the problem of overcrowding and authorization of spectrum in radio-frequency radio-based solutions; VLC can also achieve extremely high symbol transmission rates, especially suitable for high density of access devices And occasions with limited network coverage. In addition, VLC has many other advantages, including universal infrastructure, wide transmission frequency, no need to occupy existing spectrum resources, no electromagnetic interference, low equipment cost, long life, safety and environmental protection, etc., which has very broad development prospects.

The indoor environment is very suitable for the application of VLC, so the existing radio system can be combined with the visible light system to extend the radio signal coverage from outdoor to indoor and maintain stable reception performance.

Summary of the invention

The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

To this end, an object of the present invention is to provide a photoelectric hybrid single frequency network broadcasting method, which improves the indoor coverage performance of the broadcasting system through the combination of a radio system and a visible light system.

Another object of the present invention is to provide a photoelectric hybrid single frequency network broadcasting system.

In order to achieve the above objective, one aspect of the present invention proposes a photoelectric hybrid single frequency network broadcasting method, which includes the following steps: Step S1, through the control center to simultaneously send data streams and control signals to the radio transmitter and the visible light transmitter, and use the single frequency network The adapter ensures the synchronization between the data stream and the radio transmitter; step S2, the radio transmitter and the visible light transmitter perform the same digital signal processing before digital/analog conversion, and then according to the physical properties of different signals The features are processed by analog signal respectively to obtain radio signals and visible light signals; step S3, the radio signal or the visible light signal is received by the receiver alone, or the radio signal and the visible light signal are received at the same time, and according to the preset Way to superimpose the radio signal and the visible light signal.

The photoelectric hybrid single frequency network broadcasting method of the embodiment of the present invention, through the combination of the radio system and the visible light system, utilizes the indoor transmission advantage of the visible light system, and compensates for the lack of indoor coverage of the radio system; The reasonable design realizes an equivalent hybrid single frequency network system architecture, saves frequency resources, and improves spectrum utilization; through the design of the receiver, it can receive and combine the two signals to achieve indoor and outdoor signal coverage The seamless connection and seamless switching of signal reception.

In addition, the photoelectric hybrid single frequency network broadcasting method according to the foregoing embodiment of the present invention may also have the following additional technical features:

Further, in an embodiment of the present invention, the radio system applied in the photoelectric hybrid single frequency network broadcasting method includes, but is not limited to, a terrestrial digital television broadcasting system, wherein the standards of the terrestrial digital television broadcasting system include but not Limited to DTMB, DTMB-A, ISDB-T, ATSC, ATSC3.0, DVB-T and DTB-T2.

Further, in an embodiment of the present invention, the step S1 further includes: the control signal is sent by a control center, and the control signal includes, but is not limited to, interleaving, channel coding, modulation, framing, Intermediate frequency points and frame structure; the single frequency network adapter adds a mega-frame initialization packet MIP to the data stream, and the mega-frame initialization packet MIP includes but is not limited to a standard frequency and a standard time.

Further, in an embodiment of the present invention, the same digital signal processing process of the radio transmitter and the visible light transmitter before digital/analog conversion includes, but is not limited to, scrambling, channel coding, modulation, interleaving, and grouping. Frame, baseband signal shaping, baseband signal up-conversion to intermediate frequency signal, digital filtering, I channel and Q channel mixing and digital/analog conversion.

Further, in an embodiment of the present invention, the step S2 further includes: after the digital/analog conversion, the radio transmitter up-converts the intermediate frequency signal into a radio frequency signal, and uses an antenna to send the radio signal to the receiver; After the digital/analog conversion of the visible light transmitter, the intermediate frequency signal is applied to the DC bias driving the light-emitting diode through an optical modulation method, and the light-emitting diode is used to send the visible light signal to the receiver.

Further, in an embodiment of the present invention, the receiver uses an antenna to receive the radio signal, uses a photodetector to receive the visible light signal, or receives a mixed signal of the radio signal and the visible light signal.

Further, in an embodiment of the present invention, when the receiver receives the mixed signal, the radio signal and the visible light signal need to be combined with different weights. The combination method includes but is not limited to the maximum ratio. Merging, equal gain merge and selective merge.

Further, in an embodiment of the present invention, the radio signal and the visible light signal each have independent signal paths and automatic gain control to ensure that both signals can be received independently.

Further, in an embodiment of the present invention, the radio transmitter and the visible light transmitter work at the same intermediate frequency to achieve an equivalent optoelectronic hybrid single-frequency network, wherein the modulus/digital of the different receiving modes The conversion process and the digital signal processing process are unified, and both are equivalent to the case of single-channel reception.

In order to achieve the above objective, another aspect of the present invention proposes a photoelectric hybrid single frequency network broadcasting system, which includes: a control module for simultaneously sending data streams and control signals to the radio transmitter and the visible light transmitter through the control center, and using The single frequency network adapter ensures the synchronization between the data stream and the transmitter; the transmitter module is used for the radio transmitter and the visible light transmitter to perform the same digital signal processing before the digital/analog conversion, and then According to the physical characteristics of different signals, analog signal processing is performed to obtain radio signals and visible light signals; the receiver module is used to receive the radio signals or the visible light signals separately through the receiver, or simultaneously receive the radio signals and the visible light signals. The visible light signal is superimposed on the radio signal and the visible light signal according to a preset manner.

The photoelectric hybrid single frequency network broadcasting system of the embodiment of the present invention, through the combination of the radio system and the visible light system, utilizes the indoor transmission advantages of the visible light system, and compensates for the lack of indoor coverage of the radio system; The reasonable design realizes an equivalent hybrid single frequency network system architecture, saves frequency resources, and improves spectrum utilization; through the design of the receiver, it can receive and combine the two signals to achieve indoor and outdoor signal coverage The seamless connection and seamless switching of signal reception.

The additional aspects and advantages of the present invention will be partly given in the following description, and partly will become obvious from the following description, or be understood through the practice of the present invention.

Description of the drawings

The above and/or additional aspects and advantages of the present invention will become obvious and easy to understand from the following description of the embodiments in conjunction with the accompanying drawings, in which:

Fig. 1 is a flowchart of a photoelectric hybrid single frequency network broadcasting method according to an embodiment of the present invention;

FIG. 2 is a flowchart of a method for broadcasting a photoelectric hybrid single frequency network according to an embodiment of the present invention;

Fig. 3 is a transmitter block diagram of a photoelectric hybrid single frequency network broadcasting method provided by an embodiment of the present invention;

4 is a schematic diagram of a signal frame structure provided by an embodiment of the present invention;

FIG. 5 is a schematic diagram of a network architecture of a photoelectric hybrid single frequency network broadcasting system provided by an embodiment of the present invention;

Fig. 6 is a schematic structural diagram of a photoelectric hybrid single frequency network broadcasting system provided by an embodiment of the present invention.

Detailed ways

The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary, and are intended to explain the present invention, but should not be construed as limiting the present invention.

Based on the applicability of VLC to indoor environments, the embodiments of the present invention combine an existing radio system with a visible light system, expand the coverage of radio signals from outdoor to indoor, and maintain stable reception performance. Compared with a single system, such a photoelectric hybrid single frequency network broadcasting system can achieve seamless connection of indoor and outdoor signal coverage and seamless switching of signal reception.

In the design of the network architecture, the single frequency network can achieve efficient and reliable signal coverage due to its advantages of saving frequency resources and improving spectrum utilization. Within the framework of a single frequency network, different transmitters broadcast the same program content synchronously on the same frequency channel, which has the advantages of compensating for time delay, saving power consumption, and overcoming near-far effects. Through reasonable design, the spectrum of the radio system and the visible light system can be adjusted and unified to form an equivalent photoelectric hybrid single-frequency networking architecture, so that the radio signal and the visible light signal can share the analog-to-digital converter, so as to realize the baseband signal Unified processing, reducing hardware costs.

In order to realize the single-frequency network architecture, a reasonable design of the radio transmitter and the visible light transmitter is required, and the focus is on the adjustment of the existing visible light transmitter. Traditional visible light transmitters mostly use baseband modulation. The digital baseband signal is converted into an analog signal by a digital-to-analog converter to directly drive the LED, and such a signal is required to be a positive real signal. In the embodiment of the present invention, the visible light transmitter no longer uses baseband modulation and a special modulation method for visible light signals, but uses intermediate frequency modulation and uses an I/Q mixer to generate real signals, which is consistent with radio signal processing. The visible light signal carrying information is loaded on the DC bias voltage driving the LED to ensure that the LED sends a positive signal.

When the receiver is near the indoor and outdoor boundary or in a similar environment, it can be considered to be within the coverage of the radio system and the visible light system at the same time, and can receive both signals at the same time. Therefore, the receiver in the embodiment of the present invention can not only independently receive the radio signal and the visible light signal, but also can receive the mixed signal of the two and perform superposition in different ways.

The photoelectric hybrid single frequency network broadcasting method and system proposed according to the embodiments of the present invention will be described below with reference to the drawings. First, the photoelectric hybrid single frequency network broadcasting method proposed according to the embodiments of the present invention will be described with reference to the accompanying drawings.

Fig. 1 is a flowchart of an opto-electronic hybrid single frequency network broadcasting method according to an embodiment of the present invention.

As shown in Figure 1, the photoelectric hybrid single frequency network broadcasting method includes the following steps:

In step S1, the data stream and control signal are simultaneously sent to the radio transmitter and the visible light transmitter through the control center, and the single frequency network adapter is used to ensure synchronization between the data stream and the radio transmitter.

Specifically, as shown in Figure 2, the control center sends data streams and control signals to the radio transmitter and the visible light transmitter at the same time, and uses a single frequency network adapter to ensure synchronization with the transmitter.

Further, in an embodiment of the present invention, step S1 also includes: the control signal is sent by the control center, the control signal includes but not limited to interleaving mode, channel coding mode, modulation mode, framing mode, intermediate frequency point and frame structure The single frequency network adapter adds the mega-frame initialization package MIP to the data stream. The mega-frame initialization package MIP includes but is not limited to information such as standard frequency and standard time.

It should be noted that the radio system used in the photoelectric hybrid single frequency network broadcasting method includes but is not limited to terrestrial digital television broadcasting systems, preferably including DTMB, DTMB-A, ISDB-T, ATSC, ATSC3.0, DVB-T , DTB-T2 and other standards.

The data stream sent by the control center is the multimedia program data to be sent by broadcasting. The sent control signal includes but is not limited to interleaving, channel coding, modulation, framing, intermediate frequency, frame structure and other information; single frequency network adapter Add Mega Frame Initialization Packet (MIP) to the data stream, including but not limited to standard frequency, standard time and other information.

The only control center controls all transmitters in the network, and each transmitter is controlled by a single frequency network adapter to realize the single frequency network architecture.

In step S2, the radio transmitter and the visible light transmitter perform the same digital signal processing before the digital/analog conversion, and then perform analog signal processing according to the physical characteristics of different signals to obtain the radio signal and the visible light signal.

That is to say, as shown in Figure 2, the digital signal processing procedures of the radio transmitter and the visible light transmitter before the digital/analog conversion are consistent, and then different transmitters process and send separately according to the physical characteristics of different signals.

As shown in Figure 3, the same digital signal processing process before digital/analog conversion in the embodiment of the present invention includes but is not limited to scrambling, channel coding, modulation, interleaving, framing, baseband signal shaping, and baseband signal up-conversion to intermediate frequency Signal, digital filtering, I-channel and Q-channel mixing, digital/analog conversion, etc.

Further, in an embodiment of the present invention, the radio transmitter and the visible light transmitter work at the same intermediate frequency frequency to realize an equivalent photoelectric hybrid single-frequency networking. Preferably, the indoor visible light system can adopt a scheme in which multiple LEDs share a light modulator to realize a single-frequency visible light network.

After the digital/analog conversion, the radio transmitter up-converts the intermediate frequency signal into a radio frequency signal, and uses the antenna to send the radio signal; after the digital/analog conversion, the visible light transmitter uses the optical modulation method to load the intermediate frequency signal on the DC driving the LED Bias, use LED to send visible light signal.

Further, in an embodiment of the present invention, step S2 further includes:

After the digital/analog conversion, the radio transmitter up-converts the intermediate frequency signal into a radio frequency signal, and uses the antenna to send the radio signal to the receiver;

After the digital/analog conversion of the visible light transmitter, through the optical modulation method, the intermediate frequency signal is loaded on the DC bias that drives the light emitting diode, and the light emitting diode is used to send the visible light signal to the receiver.

In step S3, the radio signal or the visible light signal is received by the receiver alone, or the radio signal and the visible light signal are received at the same time, and the radio signal and the visible light signal are superimposed according to a preset manner.

Specifically, the receiver can use an antenna to receive radio signals, can use a photodetector to receive visible light signals, or receive a mixed signal of radio signals and visible light signals. Among them, the radio signal and the visible light signal each have independent signal paths and automatic gain control to ensure independent reception and mixed reception of the two signals. Among them, the analog/digital conversion process and digital signal processing process of different receiving modes are unified. Both are equivalent to the case of single-channel reception. Further, in an embodiment of the present invention, when the receiver receives the mixed signal, the radio signal and the visible light signal can be combined with different weights. The combination method includes but is not limited to maximum ratio combining (MRC) and equal gain combining (EGC). ), select merge (SC), etc.

In other words, the receiver can receive radio signals or visible light signals alone, or can receive two signals at the same time, and superimpose the two signals in different combinations.

Regardless of whether the two signals are received independently or mixed, the analog/digital conversion and subsequent demodulation, decoding and other digital signal processing procedures are unified, which is equivalent to the case of single-channel reception.

The above method will be illustrated by specific embodiments below.

Example one

This embodiment shows an application in a downlink communication system for broadband digital terrestrial broadcasting. The system requires four downlink SD digital TV broadcast services within a given bandwidth, and the receiver only receives radio signals or visible light signals sent by a certain transmitter. The method flow and transmission mode involved are detailed as follows:

The control center sends data streams and control signals to the radio transmitter and visible light transmitter at the same time, and uses a single frequency network adapter to ensure synchronization with the transmitter.

The foregoing transmission service requires four-channel SD digital TV broadcast service transmission, and each signal frame is divided into four time domain sub-channels, uplink time slots, and signaling information. Each sub-channel is responsible for transmitting a service; the uplink time slot provides conditions for the sending and receiving of uplink information; and the signaling information is responsible for indicating the corresponding service according to the user's uplink signal feedback. For each sub-service of digital TV transmission in the sub-channel, the modulation method is as follows:

The system bandwidth is 8MHz, the channel bandwidth is also 8MHz, the radio signal carrier frequency is 634MHz, and the LED blinking speed is 10MHz. Refer to China's digital TV terrestrial broadcasting standard DTMB, the analog front end adopts time-domain filtering shaping, the shaping filter is selected as SRRC filter, the roll-off factor is 0.05, the basic symbol rate is selected as 7.56MHz, and the basic symbol interval is (1/7.56)us ≈0.1323us.

Considering that the randomization of the transmitted digital signal is helpful to the transmission information processing, the transmitted digital signal needs to be scrambled. The scrambling code is a pseudo-random sequence with the maximum length of the binary system, and the generator polynomial is defined as

G(x)=1+x ¹⁴ +x ¹⁵

The initial phase of this sequence is defined as 100101010000000.

Encode the scrambling result to obtain a codeword. The coding method adopted is forward error correction coding, which is formed by concatenating the outer code and the inner code. The outer code is a BCH code, and the inner code is an LDPC (7493, 3048) code with an equivalent coding rate of 0.4. Perform constellation mapping on the obtained codeword to generate complex symbols corresponding to the codeword, and the constellation mapping method is 64QAM. Time domain interleaving adopts convolutional interleaving coding based on constellation symbols. The time domain interleaving results and system information parameters form frequency domain data blocks. Each frequency domain data block is 3780 long, including 3744 data symbols and 36 system information parameter symbols. . The frequency domain data block is transformed by 3780-point IDFT to obtain the time domain data block.

TDS-OFDM is used as the framing technology, and a guard interval composed of a known auxiliary sequence and its preamble and postsynchronization is selected as the padding between time domain data blocks. Among them, the auxiliary sequence is a known PN sequence obtained by IDFT transformation , The length is 255 symbols, the preamble and postamble are cyclic extensions of the PN sequence, the preamble length is 82 symbols, the postamble length is 83 symbols, and the guard interval is 420 symbols in total. The time domain data block and the guard interval are combined into a first signal frame. In each first signal frame, PN sequences of different phases are used as auxiliary sequences according to the timing signal of the current frame.

The above-mentioned baseband signal processing process is not carried out in the control part. The control center only sends synchronized original data and control signals to each transmitter. The control signal includes the above-mentioned channel division method, signal frame structure, coding method, modulation method and other baseband signals. Processing information and parameters.

The single frequency network adapter adds the MIP including but not limited to standard frequency, standard time and other information to the data stream, and controls the intermediate frequency of all transmitters to 10MHz.

The digital signal processing process of the radio transmitter and the visible light transmitter before the digital/analog conversion is kept the same, and then different transmitters process and send separately according to the physical characteristics of different signals.

Each transmitter performs baseband processing on the original data according to the received control signal, then up-converts the baseband signal to an intermediate frequency signal with a uniform frequency point, and obtains the analog intermediate frequency through digital filtering, real part acquisition, digital/analog conversion and other signal processing processes signal.

The framing modes of different transmitters are the same. All four-channel services are time-domain framing based on control information. The schematic diagram of the frame structure is shown in Figure 4 to obtain the transmitted signal.

Since then, different transmitters send signals in different ways: the radio transmitter directly up-converts the intermediate frequency signal to a radio frequency signal, and uses an antenna to transmit the radio signal; the visible light transmitter uses the optical modulation method to load the intermediate frequency signal on the DC bias that drives the LED Above, use the drive circuit to convert the voltage signal into the current signal, which is used to drive multiple different LEDs to emit light and adjust the light intensity.

The receiver can receive radio signals or visible light signals alone, or it can receive two signals at the same time and superimpose them in different ways.

In the embodiment of the present invention, the receiver only receives the radio signal or the visible light signal sent by a certain transmitter, so it only receives a single channel, and there is no problem of selective combination. For radio signals, the receiver uses an antenna to receive and completes automatic gain control; for visible light signals, the receiver uses a photodetector to receive, detect the intensity of the light signal and convert it into an electrical signal, and also complete automatic gain control. The signal obtained in this way is actually an intermediate frequency signal. The subsequent signal processing is the same for the two signals, including but not limited to analog/digital conversion, filtering, down-conversion, etc. After obtaining the baseband signal, it is synchronized and demodulated and decoded to obtain the transmission digital Signal, and demodulate the program you need according to the instructions of the signaling information.

Example two

This embodiment provides an application in a duplex communication system for broadband wireless digital communication for selectable services. The system requires four downlink SD digital TV broadcast services within a given bandwidth, and can adjust each service according to the user's uplink feedback; the uplink is realized by WiFi, and the downlink is realized by a single-frequency network system of optical and electrical hybrid; The system can serve multiple users, and the receiver of each user simultaneously receives a radio signal and a visible light signal. The method flow and transmission mode involved are detailed as follows:

The foregoing transmission service requires four-channel SD digital TV broadcast service transmission, and each signal frame is divided into four time domain sub-channels, uplink time slots, and signaling information. Each sub-channel is responsible for transmitting a service; the uplink time slot provides conditions for the sending and receiving of uplink information; the signaling information is responsible for indicating the corresponding service according to the user's uplink signal feedback, which needs to be adjusted according to the user's uplink feedback. For each sub-service of digital TV transmission in the sub-channel, the modulation method is as follows:

The system bandwidth is 30MHz, the channel bandwidth is also 30MHz, the radio signal carrier frequency is 634MHz, and the LED blinking speed is 30MHz. The analog front end adopts frequency domain sub-carrier shaping to realize spectrum shaping. The basic symbol rate is selected as 30.00MHz, the basic symbol interval is (1/30.00)us≈0.0333us, and the effective signal bandwidth is 28MHz, and the frequency domain subcarriers outside the effective bandwidth are used to carry zero symbols (ie virtual subcarriers).

G(x)=1+x ¹⁴ +x ¹⁵

The initial phase of this sequence is defined as 100101010000000.

Encode the scrambling result to obtain a codeword. The coding method adopted is forward error correction coding, which is formed by concatenating the outer code and the inner code. The outer code is a BCH code, and the inner code is an LDPC code with a coding rate of 0.5 and a code length of 64800 bits. After bit interleaving the obtained codeword, the complex symbols corresponding to the codeword are generated by constellation mapping, and the constellation mapping method is 64QAM. Time-domain interleaving adopts convolutional interleaving coding based on constellation symbols. As a result of time-domain interleaving, pilot subcarriers and virtual subcarriers are added at predetermined positions to form frequency domain data blocks. The length of each frequency domain data block is 8192, of which the first 548 subcarriers are virtual subcarriers, among the last 7644 subcarriers, 1/6 carries pilot symbols, and 5/6 carries data symbols. The frequency domain data block is transformed by 8192-point IDFT to obtain the time domain data block.

Using CP-OFDM as the framing technology, the cyclic extension of the time domain data block is selected as the guard interval filling, and the guard interval is 512 symbols in total length. The time domain data block and the guard interval are combined into the first signal frame. Since point-to-point forwarding communication is considered in this embodiment, the address insertion unit needs to add predetermined receiving address information after the signal synchronization header.

Similarly, the above-mentioned baseband signal processing process is not carried out in the control part. The control center only sends synchronized original data and control signals to each transmitter. The control signal includes the above-mentioned channel division method, signal frame structure, coding method, and modulation method. And other baseband signal processing information and parameters.

According to the instructions in the signaling information, the service information required by each user can be obtained, and each transmitter can extract the sub-service of the corresponding time domain sub-channel. For services that users do not need, just send blank time slots. For the services required by users, different transmitters send signals in different ways: the radio transmitter directly up-converts the intermediate frequency signal into a radio frequency signal, and uses an antenna to transmit the radio signal; the visible light transmitter loads the intermediate frequency signal on the driving LED through the optical modulation method On the DC bias, a drive circuit is used to convert the voltage signal into a current signal, which is used to drive multiple different LEDs to emit light and adjust the luminous intensity.

In the embodiment of the present invention, the receiver simultaneously receives a radio signal and a visible light signal. For radio signals, the receiver uses an antenna to receive and completes automatic gain control; for visible light signals, the receiver uses a photodetector to receive, detect the intensity of the light signal and convert it into an electrical signal, and also complete automatic gain control.

Since the communication system in the embodiment of the present invention is a single-frequency network architecture, the two signals obtained in this way are both intermediate frequency signals and have the same frequency points. Different strategies can be used to combine them into one signal: if the maximum ratio is used, the two signals are adjusted. The weighting coefficient of the channel signals maximizes the combined signal-to-noise ratio; equal gain combining is used to combine the two signals with the same weight; when selective combining is used, the signal with a larger channel is selected as the combined result.

For the signal after selective combination, signal processing including but not limited to analog/digital conversion, filtering, down-conversion, etc., obtain the baseband signal after synchronization and demodulation decoding to obtain the transmission digital signal, and according to the instructions of the signaling information To demodulate the program you need.

Users have the right to choose the services they receive, and they can feed back to the transmitter through the WiFi system to adjust the signaling information to change their services. Since the coverage of the WiFi system is mainly indoors, the visible light transmitter in the photoelectric hybrid system should be received for user uplink feedback. Correspondingly, the visible light transmitter needs to add a WiFi receiving module and transmit the received information to the visible light signal transmitter.

Example three

This embodiment provides an application in a downlink communication system oriented to broadband digital terrestrial broadcasting that can be positioned. The system requires the provision of four downlink SD digital TV broadcast services within a given bandwidth; each transmitter needs to transmit related information for positioning in addition to the service data, and the indoor visible light transmitter uses a shared optical modulator solution Realize visible light single frequency networking; the receiver can receive multiple radio signals and multiple visible light signals at the same time. The method flow and transmission mode involved are detailed as follows:

The foregoing transmission service requires four-channel SD digital TV broadcast service transmission, and each signal frame is divided into four time domain sub-channels, uplink time slots, and signaling information. Each sub-channel is responsible for transmitting a service; the uplink time slot provides conditions for the sending and receiving of uplink information; the signaling information is responsible for indicating the corresponding service according to the user's uplink signal feedback, and inserting relevant information for positioning, including but It is not limited to the three-dimensional coordinates of the transmitter, the signal transmission time, etc., and varies with positioning principles and algorithms. For each sub-service of digital television transmission in the sub-channel, the modulation method is the same as in the first embodiment.

Similarly, the baseband signal processing process is not carried out in the control part. The control center only sends synchronized original data and control signals to each transmitter. The control signal includes the above-mentioned channel division method, signal frame structure, coding method, modulation method, etc. Signal processing information and parameters.

Similarly, the data processing process, framing process, signal sending process, etc. of each transmitter are the same as in the first embodiment.

The receiver in the embodiment of the present invention can simultaneously receive multiple radio signals and multiple visible light signals. For radio signals, the receiver uses an antenna to receive and completes automatic gain control; for visible light signals, the receiver uses a photodetector to receive, detect the intensity of the light signal and convert it into an electrical signal, and also complete automatic gain control.

Afterwards, the relevant information for positioning is extracted from the signaling information part of the signal frame of each signal, and the positioning algorithm and the positioning information are used to perform positioning calculations to achieve positioning.

Since the communication system in the embodiment of the present invention is a single frequency network architecture, the received multiple signals are all intermediate frequency signals with the same frequency, and the service data information except for the positioning information is the same, so the received mixed signal is Signals affected by multipath channels need to be equalized to eliminate the effects of multipath. Preferably, since each channel of the multipath caused by the single frequency network has useful power, these signal powers should be reasonably used, so the equalization process can be performed simultaneously with the subsequent selective combination of multiple channels. The combination method can be the same as that of the second embodiment. Corresponding parts in the same, can also be improved on this basis.

For the final received signal, perform signal processing including but not limited to analog-to-digital conversion, filtering, down-conversion, etc. After obtaining the baseband signal, it is synchronized and demodulated and decoded to obtain the transmission digital signal, and can be in accordance with the instructions of the signaling information To demodulate the program you need.

In summary, as shown in Figure 5, the photoelectric hybrid single frequency network broadcasting method proposed according to the embodiment of the present invention, through the combination of the radio system and the visible light system, utilizes the indoor transmission advantages of the visible light system to compensate for the radio system’s indoor coverage Insufficiency; through the reasonable design of radio transmitters and visible light transmitters, an equivalent hybrid single-frequency network system architecture is realized, which saves frequency resources and improves spectrum utilization; through the design of receivers, it can handle both signals Receiving and merging realize the seamless connection of indoor and outdoor signal coverage and seamless switching of signal reception.

Next, the photoelectric hybrid single frequency network broadcasting system according to the embodiments of the present invention will be described with reference to the accompanying drawings.

Fig. 6 is a schematic structural diagram of a photoelectric hybrid single frequency network broadcasting system according to an embodiment of the present invention.

As shown in FIG. 6, the photoelectric hybrid single frequency network broadcasting system 10 includes: a control module 101, a transmitter module 102, and a receiver module 103.

Specifically, the control module 101 is configured to simultaneously send data streams and control signals to the radio transmitter and the visible light transmitter through the control center, and use a single frequency network adapter to ensure synchronization between the data stream and the transmitter. The transmitter module 102 is used for the radio transmitter and the visible light transmitter to perform the same digital signal processing before digital/analog conversion, and then to perform analog signal processing according to the physical characteristics of different signals to obtain radio signals and visible light signals; receiver module 103 It is used to receive radio signals or visible light signals through the receiver alone, or receive radio signals and visible light signals at the same time, and superimpose the radio signals and visible light signals according to a preset method.

It should be noted that the foregoing explanation of the embodiment of the photoelectric hybrid single frequency network broadcasting method is also applicable to the system and will not be repeated here.

According to the photoelectric hybrid single frequency network broadcasting system proposed by the embodiment of the present invention, through the combination of the radio system and the visible light system, the indoor transmission advantages of the visible light system are used to compensate for the lack of indoor coverage of the radio system; The reasonable design of the transmitter realizes an equivalent hybrid single frequency network system architecture, saves frequency resources and improves spectrum utilization; through the design of the receiver, it can receive and combine the two signals, realizing indoor and outdoor Seamless connection of signal coverage and seamless switching of signal reception.

In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

In the present invention, unless otherwise clearly defined and defined, the terms "installed", "connected", "connected", "fixed" and other terms should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. , Or integrated; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, it can be the internal communication of two components or the interaction relationship between two components, unless otherwise specified The limit. For those of ordinary skill in the art, the specific meaning of the above-mentioned terms in the present invention can be understood according to specific circumstances.

In the present invention, unless expressly stipulated and defined otherwise, the first feature “on” or “under” the second feature may be in direct contact with the first and second features, or the first and second features may be indirectly through an intermediary. contact. Moreover, the "above", "above" and "above" of the first feature on the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the level of the first feature is higher than the second feature. The “below”, “below” and “below” of the second feature of the first feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the level of the first feature is smaller than the second feature.

In the description of this specification, descriptions with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean specific features described in conjunction with the embodiment or example , Structure, materials or features are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples and the characteristics of the different embodiments or examples described in this specification without contradicting each other.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above-mentioned embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can comment on the foregoing within the scope of the present invention. The embodiment undergoes changes, modifications, substitutions and modifications.

Claims

An opto-electronic hybrid single frequency network broadcasting method is characterized in that it comprises the following steps:

Step S1, sending data streams and control signals to the radio transmitter and the visible light transmitter simultaneously through the control center, and using a single frequency network adapter to ensure synchronization between the data stream and the radio transmitter;

Step S2, the radio transmitter and the visible light transmitter perform the same digital signal processing before digital/analog conversion, and then perform analog signal processing respectively according to the physical characteristics of different signals to obtain radio signals and visible light signals;

In step S3, the radio signal or the visible light signal is received by a receiver alone, or the radio signal and the visible light signal are received at the same time, and the radio signal and the visible light signal are superimposed according to a preset manner.
The photoelectric hybrid single frequency network broadcasting method according to claim 1, wherein the radio system applied in the photoelectric hybrid single frequency network broadcasting method includes, but is not limited to, a terrestrial digital television broadcasting system, wherein the terrestrial digital television The standards of the broadcasting system include but are not limited to DTMB, DTMB-A, ISDB-T, ATSC, ATSC3.0, DVB-T and DTB-T2.
The photoelectric hybrid single frequency network broadcasting method according to claim 1, wherein the step S1 further comprises:

The control signal is sent by the control center, and the control signal includes, but is not limited to, an interleaving method, a channel coding method, a modulation method, a framing method, an intermediate frequency point, and a frame structure;

The single frequency network adapter adds a mega-frame initialization packet MIP to the data stream. The mega-frame initialization packet MIP includes but is not limited to a standard frequency and a standard time.
The photoelectric hybrid single frequency network broadcasting method according to claim 1, wherein the same digital signal processing process of the radio transmitter and the visible light transmitter before digital/analog conversion includes, but is not limited to, scrambling code, channel Encoding, modulation, interleaving, framing, baseband signal shaping, baseband signal up-conversion to intermediate frequency signal, digital filtering, I-channel and Q-channel mixing, and digital/analog conversion.
The photoelectric hybrid single frequency network broadcasting method according to claim 1, wherein said step S2 further comprises:

After the digital/analog conversion, the radio transmitter up-converts the intermediate frequency signal into a radio frequency signal, and uses an antenna to send the radio signal to the receiver;

After the digital/analog conversion of the visible light transmitter, the intermediate frequency signal is applied to the DC bias driving the light-emitting diode through an optical modulation method, and the light-emitting diode is used to send the visible light signal to the receiver.
The photoelectric hybrid single frequency network broadcasting method according to claim 1, wherein the receiver uses an antenna to receive the radio signal, uses a photodetector to receive the visible light signal, or receives the radio signal and the radio signal. Mixed signal of visible light signal.
The photoelectric hybrid single frequency network broadcasting method according to claims 1 and 6, wherein when the receiver receives the mixed signal, the radio signal and the visible light signal need to be combined with different weights, wherein The method of combining includes, but is not limited to, maximum ratio combining, equal gain combining, and selective combining.
The photoelectric hybrid single frequency network broadcasting method according to claims 1 and 6, characterized in that the radio signal and the visible light signal each have independent signal paths and automatic gain control to ensure independent reception of the two signals. Hybrid reception, where the analog/digital conversion process and digital signal processing process of different reception modes are unified, and both are equivalent to the case of single-channel reception.
The photoelectric hybrid single frequency network broadcasting method according to claim 1, wherein the radio transmitter and the visible light transmitter work at the same intermediate frequency to achieve an equivalent photoelectric hybrid single frequency network.
A photoelectric hybrid single frequency network broadcasting system, which is characterized in that it comprises:

The control module is configured to simultaneously send data streams and control signals to the radio transmitter and the visible light transmitter through the control center, and use a single frequency network adapter to ensure synchronization between the data stream and the transmitter;

The transmitter module is used for the radio transmitter and the visible light transmitter to perform the same digital signal processing before digital/analog conversion, and then to perform analog signal processing respectively according to the physical characteristics of different signals to obtain radio signals and visible light signals ；

The receiver module is used to receive the radio signal or the visible light signal through a receiver alone, or receive the radio signal and the visible light signal at the same time, and combine the radio signal and the visible light signal in a preset manner Overlay.