Automatic antenna selection circuit based on TDD communication system and TDD communication device

Abstract

The invention provides an automatic antenna selection circuit based on a TDD communication system and TDD communication equipment. The automatic antenna selection circuit comprises a radio frequency switch, a plurality of coupling detection circuits and a plurality of comparison circuits, a first port of the first coupling detection circuit is connected with a TDD information source, a second port is connected with the input end of the radio frequency switch, and a third port is connected with the first comparison circuit; the first port of the second coupling detection circuit is connected with the first output end of the radio frequency switch, the second port is connected with the first antenna, and the third port is connected with the second comparison circuit; the first port of the third coupling detection circuit is connected with the second output end of the radio frequency switch, the second port is connected with the second antenna, and the third port is connected with the second comparison circuit; the first comparison circuit outputs an enable signal to an enable end of the second comparison circuit according to a comparison result of the first detection signal and the reference signal; the second comparison circuit outputs a control signal to the radio frequency switch according to a comparison result of the second detection signal and the third detection signal.

Description

Technical Field

[0001] The present application relates to the field of wireless communication technologies, and particularly to an automatic antenna selection circuit and a TDD communication device based on a TDD communication system. Background Art

[0002] In a wireless communication system, the performance of an antenna directly affects the signal reception quality. Conventional wireless communication devices usually adopt a fixed antenna or a manual antenna switching method, and cannot dynamically select the optimal antenna in real time according to the signal strength, resulting in unstable communication quality. Especially in an environment with severe multipath effects and signal interference, the fixed antenna or manual switching method is difficult to meet the requirements of high-quality communication.

[0003] To solve the above problems, some automatic antenna selection schemes have been proposed in the prior art. However, these schemes usually have high complexity, high cost, and problems such as switching delay and mis-switching in practical applications. Therefore, there is an urgent need for an automatic antenna selection circuit with a simple structure, low cost, fast speed, high efficiency, and stable performance. Summary of the Invention

[0004] In view of this, the present application provides an automatic antenna selection circuit and a TDD communication device based on a TDD communication system, aiming to realize low-cost, real-time, and stable automatic antenna selection through a hardware circuit and improve the communication quality.

[0005] In a first aspect, the present application provides an automatic antenna selection circuit based on a TDD communication system, including a radio frequency switch, a plurality of coupling and detection circuits, and a plurality of comparison circuits. The plurality of coupling and detection circuits at least include a first coupling and detection circuit, a second coupling and detection circuit, and a third coupling and detection circuit. The plurality of comparison circuits at least include a first comparison circuit and a second comparison circuit;

[0006] A first port of the first coupling and detection circuit is connected to a TDD signal source, a second port is connected to an input end of the radio frequency switch, and a third port is connected to a first input end of the first comparison circuit;

[0007] A first port of the second coupling and detection circuit is connected to a first output end of the radio frequency switch, a second port is connected to a first antenna, and a third port is connected to a first input end of the second comparison circuit;

[0008] A first port of the third coupling and detection circuit is connected to a second output end of the radio frequency switch, a second port is connected to a second antenna, and a third port is connected to a second input end of the second comparison circuit;

[0009] The first input terminal of the first comparison circuit receives the first detection signal output by the first coupling and detection circuit, and the second input terminal receives a reference signal. The first comparison circuit outputs an enable signal to the enable terminal of the second comparison circuit according to the comparison result of the first detection signal and the reference signal to control the working state of the second comparison circuit;

[0010] The first input terminal of the second comparison circuit receives the second detection signal output by the second coupling and detection circuit, and the second input terminal receives the third detection signal output by the third coupling and detection circuit. The second comparison circuit outputs a control signal to the RF switch according to the comparison result of the second detection signal and the third detection signal to control the switching of the RF switch.

[0011] As described above, the present application designs an automatic antenna selection circuit including an RF switch, a plurality of coupling and detection circuits, and a plurality of comparison circuits. The first coupling and detection circuit detects the signal of the TDD (Time Division Duplexing) signal source to obtain the state of the TDD signal source, and the first comparison circuit compares the detected signal with the reference signal to output the enable signal of the second comparison circuit. Then, the second coupling and detection circuit and the third coupling and detection circuit respectively detect the signal energies of the first antenna and the second antenna and output them to the second comparison circuit for comparison, and output a control signal for controlling the switching of the RF switch according to the comparison result, so as to ensure that the TDD signal source can communicate using the antenna with stronger signal. The circuit structure of the present application is simple, can real-time detect the intensity of the received signal, and automatically select the antenna with stronger signal for communication, thereby improving the communication quality.

[0012] Optionally, the RF switch includes a single-pole multi-throw switch. The stationary terminal of the single-pole multi-throw switch is connected to the second port of the first coupling and detection circuit, the first moving terminal of the single-pole multi-throw switch is connected to the first port of the second coupling and detection circuit, and the second moving terminal of the single-pole multi-throw switch is connected to the first port of the third coupling and detection circuit.

[0013] As described above, by using a single-pole multi-throw switch as the RF switch, the number of moving terminals of the single-pole multi-throw switch can be extended to N (N≥2) to allow connection of multiple groups of antennas. By increasing the coupling and detection circuit and the comparison circuit channels, real-time detection and intelligent switching of the signal intensities of multiple antennas can be realized.

[0014] Optionally, the coupling and detection circuit includes a microstrip line coupler, a detector, and a low-pass filter;

[0015] The microstrip line coupler is used to extract the received signal energy and output a coupled signal to the detector. The detector is used to convert the coupled signal into a DC level signal and output it after being filtered by the low-pass filter.

[0016] As described above, the coupling and detection circuit, as the signal transmission circuit at the output or input end of the RF switch, can ensure wide-band coverage and high isolation by using a microstrip line coupler. It couples the signal energy on the transmission line, and after converting the coupled signal into a DC level signal through a detector, it is filtered by a low-pass filter for easy provision to the comparison circuit at the backend for comparison.

[0017] Optionally, the detector includes a diode detector or a logarithmic detector.

[0018] As described above, the detector of the present application can use a diode detector or a logarithmic detector. Among them, the diode detector converts the RF signal power into a DC voltage by utilizing the non-linear characteristics of a Schottky diode, with low power consumption, while the logarithmic detector linearly maps the input power to a logarithmic voltage output through a cascaded limiting amplifier and a logarithmic compression circuit, and the dynamic range can reach 60 dB.

[0019] Optionally, the comparison circuit includes a high-speed voltage comparator.

[0020] As described above, by using a high-speed voltage comparator to compare the input detected signal, the system timing accuracy and signal processing speed can be improved, quickly determining the magnitude relationship between two input signals and outputting a high / low level logic signal. Its response time can reach the nanosecond level, and its reference voltage signal is adjustable, thus being applicable to different signal strengths.

[0021] Optionally, the first coupling and detection circuit is used to detect the state of the TDD signal source;

[0022] When the TDD signal source is in the transmitting state, the first detected signal output by the first coupling and detection circuit is higher than the reference signal, and the first comparison circuit outputs an enabling signal with a high level, and the second comparison circuit does not work;

[0023] When the TDD signal source is in the receiving state, the first detected signal output by the first coupling and detection circuit is lower than the reference signal, and the first comparison circuit outputs an enabling signal with a low level, and the second comparison circuit works.

[0024] As described above, in a TDD system, when the TDD signal source is in the transmitting state, switching the antenna may affect the ongoing transmission. Therefore, in this application, the first coupling detection circuit is used to monitor the RF signal strength of the TDD signal source in real time. By the coordinated operation of the first comparison circuit and the second comparison circuit, intelligent switching control of the transmit / receive state is achieved. Specifically, when the signal source is transmitting, the first detection signal is higher than the reference signal, the first comparison circuit outputs a high-level enable signal, and the second comparison circuit is turned off. At this time, the RF switch does not switch. When the signal source is receiving, the first detection signal is lower than the reference signal, the first comparison circuit outputs a low-level enable signal, and the second comparison circuit is activated. At this time, the RF switch can switch.

[0025] Optionally, the second coupling detection circuit is used to extract the signal strength of the first antenna and output a second detection signal, and the third coupling detection circuit is used to extract the signal strength of the second antenna and output a third detection signal;

[0026] When the second comparison circuit is working, it outputs a control signal to the RF switch according to the comparison result of the second detection signal and the third detection signal. This control signal is used to control the RF switch to switch to the antenna with stronger signal, so that the TDD signal source communicates through the antenna with stronger signal.

[0027] As described above, by using the second coupling detection circuit and the third coupling detection circuit to extract the signal strengths of the first antenna and the second antenna respectively, and combining the real-time comparison of the second comparison circuit, it is convenient to dynamically control the RF switch to switch to the antenna with stronger signal according to the comparison result, thereby optimizing the communication performance of the TDD signal source.

[0028] In a second aspect, this application provides a TDD communication device, including the above-mentioned automatic antenna selection circuit based on a TDD communication system, which is used to optimize antenna selection in real time during time-division duplex communication.

[0029] These and other aspects of this application will become more understandable in the following description of one or more embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a circuit diagram of an automatic antenna selection circuit based on a TDD communication system provided by an embodiment of this application;

[0031] Figure 2 is a circuit diagram of a coupling detection circuit provided by an embodiment of this application.

[0032] It should be understood that in the above structural schematic diagram, the sizes and shapes of the respective block diagrams are for reference only and should not constitute an exclusive interpretation of the embodiments of the present application. The relative positions and inclusion relationships between the respective block diagrams presented in the structural schematic diagram only schematically represent the structural associations between the block diagrams, rather than limiting the physical connection manners of the embodiments of the present application. Detailed implementation manners

[0033] The following takes embodiments in conjunction with the accompanying drawings to further illustrate the technical solutions provided by the present application. It should be understood that the system structures and service scenarios provided in the embodiments of the present application are mainly for illustrating possible implementation manners of the technical solutions of the present application and should not be construed as the only limitation to the technical solutions of the present application. Those of ordinary skill in the art will know that with the evolution of the system structure and the emergence of new service scenarios, the technical solutions provided by the present application are equally applicable to similar technical problems.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. In case of inconsistency, the meaning described in this specification or the meaning derived from the content recorded in this specification shall prevail. In addition, the terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0035] The embodiments of the present application propose an automatic antenna selection circuit based on a TDD communication system, aiming to achieve low-cost, real-time, and stable antenna automatic selection through a hardware circuit and improve communication quality.

[0036] As Figure 1 shown, an automatic antenna selection circuit based on a TDD communication system provided by an embodiment of the present application includes a radio frequency switch SPDT, a plurality of coupling and detection circuits CD1, CD2, CD3, and a plurality of comparison circuits COM1, COM2;

[0037] Among them, the first port of the first coupling and detection circuit CD1 is connected to the TDD signal source Router, which is used to couple the radio frequency signal of the TDD signal source Router and convert it into a first detection signal VC1. The second port is connected to the input end of the radio frequency switch SPDT, and the third port is connected to the first input end of the first comparison circuit COM1. The first port of the second coupling and detection circuit CD2 is connected to the first output end of the radio frequency switch SPDT, and the second port is connected to the first antenna E1, which is used to couple the signal intensity of the first antenna E1 and convert it into a second detection signal VC2. The third port is connected to the first input end of the second comparison circuit COM2. The first port of the third coupling and detection circuit CD3 is connected to the second output end of the radio frequency switch SPDT, and the second port is connected to the second antenna E2, which is used to couple the signal intensity of the second antenna E2 and convert it into a third detection signal VC3. The third port is connected to the second input end of the second comparison circuit COM2.

[0038] The first input end of the first comparison circuit COM1 receives the first detection signal VC1 output by the first coupling and detection circuit CD1, and the second input end receives a reference signal VC0. The first comparison circuit outputs an enable signal VR to the enable end of the second comparison circuit COM2 according to the comparison result of the first detection signal VC1 and the reference signal VC0 to control the working state of the second comparison circuit COM2. The first input end of the second comparison circuit COM2 receives the second detection signal VC2 output by the second coupling and detection circuit, and the second input end receives the third detection signal VC3 output by the third coupling and detection circuit. The second comparison circuit outputs a control signal VC to the radio frequency switch SPDT according to the comparison result of the second detection signal VC2 and the third detection signal VC3. Through this control signal VC, the radio frequency switch SPDT can be controlled to switch and select the antenna with a stronger signal, so as to ensure that the TDD signal source can use the antenna with a stronger signal for communication.

[0039] In some embodiments, the above-mentioned radio frequency switch SPDT of the present application can adopt a high-performance single-pole multi-throw switch. The single-pole multi-throw switch can connect multiple groups of antennas by expanding the number of its moving terminals, and can realize real-time detection and intelligent switching of the signal intensities of multiple antennas by adding coupling detection circuits and comparison circuit channels. Taking a single-pole double-throw switch as an example, the single-pole double-throw switch has a fixed terminal and two moving terminals, with a switching time less than 100 nanoseconds, a working frequency range covering 0.1 GHz to 7.5 GHz, and is compatible with 802.11n / g / ac / ax, Halow, and LoRa communication standards. The fixed terminal of the single-pole double-throw switch is connected to the second port of the first coupling detection circuit CD1, one moving terminal of the single-pole double-throw switch is connected to the first port of the second coupling detection circuit CD2, and the other moving terminal of the single-pole double-throw switch is connected to the first port of the third coupling detection circuit CD3. Through the single-pole double-throw switch, dynamic switching between the first antenna E1 and the second antenna E2 can be achieved, so as to ensure that the TDD signal source can use the antenna with stronger signal for communication.

[0040] In some embodiments, as Figure 2 shown, the above-mentioned coupling detection circuits CD1, CD2, and CD3 of the present application can adopt a circuit structure composed of a microstrip line coupler and a diode detector, specifically including a microstrip line connected between the P1 port and the P2 port, resistors R1, R2, a capacitor C1, and a diode D1. Among them, the bandwidth range of the microstrip line coupler can cover 2.4 GHz to 5.9 GHz, which is suitable for multi-band wireless communication, and the coupling degree can be designed to be between -10 dB and -20 dB, so as to ensure the effective extraction of signal energy. The resistor R1 can be used to limit the current of the input signal to protect other components in the circuit from the impact of large current. The diode D1 can be used as a detection diode, and the capacitor C1 and the resistor R2 together form a low-pass filter to filter the output signal.

[0041] Based on Figure 2 shown, the working principle of the coupling detection circuit is that the input signal enters through the P1 port of the coupling detection circuit, passes through the resistor R1 and then enters the diode D1. The diode D1 filters out the AC component (usually the high-frequency component) in the input signal and only allows the DC component (low-frequency component) to pass through. When the input signal is in the positive half cycle, the diode D1 conducts, allowing current to pass through and flow to the capacitor C1 for charging; when the input signal is in the negative half cycle, the diode D1 cuts off, blocking the current. The capacitor C1 is used to store charge and smooth the high-frequency component in the output voltage, making the output voltage more stable, while the resistor R2 determines the time constant of the filter and affects the speed of the voltage response. The DC signal after detection and filtering is finally output from the P3 port to be provided to the comparison circuit at the back end.

[0042] In some embodiments, the coupling and detection circuit of the present application may also adopt a logarithmic detector. By cascading a limiting amplifier and a logarithmic compression circuit, the logarithmic detector linearly maps the input power to a logarithmic voltage output, with a dynamic range of up to 60 dB, to meet the requirements of high precision and wide dynamic range.

[0043] In some embodiments, the above-mentioned comparison circuits COM1 and COM2 of the present application may adopt high-speed voltage comparators. Through the high-speed voltage comparators, the system timing accuracy and signal processing speed can be improved, the magnitude relationship between two input signals can be quickly judged, and high / low level logic signals are output. Its response time can reach the nanosecond level, and its reference voltage signal is adjustable, so as to be applicable to different signal strengths.

[0044] Based on Figure 1 - Figure 2 the circuit shown, the working principle of the automatic antenna selection circuit provided by the embodiment of the present application is as follows:

[0045] The first coupling and detection circuit CD1 couples the radio frequency signal of the TDD source Router and converts it into a first detection signal VC1, which is then output to the first comparison circuit COM1;

[0046] The first comparison circuit COM1 compares the first detection signal VC1 with the reference signal VC0. If VC1>VC0, it indicates that the TDD source Router is transmitting a signal, and the first comparison circuit COM1 outputs a low-level enable signal VR to activate the second comparison circuit COM2; if VC1≤VC0, it indicates that the TDD source Router is not transmitting (or is receiving) a signal, and the first comparison circuit COM1 outputs a high-level enable signal VR to turn off the second comparison circuit COM2;

[0047] The second coupling and detection circuit CD2 is connected to the first output end of the radio frequency switch SPDT and the first antenna E1, couples the signal strength of the first antenna E1, and converts it into a second detection signal VC2, which is sent to the first input end of the second comparison circuit COM2;

[0048] The third coupling and detection circuit CD3 is connected to the second output end of the radio frequency switch SPDT and the second antenna E2, couples the signal strength of the second antenna E2, and converts it into a third detection signal VC3, which is sent to the second input end of the second comparison circuit COM2;

[0049] After receiving the low-level enable signal VR, the second comparison circuit COM2 starts to compare the second detection signal VC2 and the third detection signal VC3, and outputs a control signal VC to the radio frequency switch SPDT according to the comparison result. The radio frequency switch SPDT (single-pole double-throw switch) has a fixed terminal and two movable terminals. The fixed terminal is connected to the output of the first coupled detection circuit CD1, and the two movable terminals are respectively connected to the inputs of the second coupled detection circuit CD2 and the third coupled detection circuit CD3. According to the control signal VC, the radio frequency switch SPDT can switch between the two movable terminals, thereby selecting different antenna paths. If VC2 is greater than VC3, the radio frequency switch SPDT switches to the first antenna E1; if VC3 is greater than VC2, it switches to the second antenna E2, so as to ensure that the TDD signal source can always use the antenna with stronger signal for communication.

[0050] In summary, the embodiment of the present application designs an automatic antenna selection circuit including a radio frequency switch, multiple coupled detection circuits and multiple comparison circuits. Through hardware-level real-time signal detection and fast switching, it effectively solves the problem of dynamic antenna selection in the TDD system. And the embodiment of the present application has the advantages of low cost and high reliability, and is applicable to various wireless communication standards, making it have significant advantages in the Internet of Things, vehicle-to-everything network and complex wireless communication environments.

[0051] It should be noted that the embodiments described in the present application are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application usually described and illustrated in the drawings can be arranged and designed in various different configurations. Therefore, the above detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the present application claimed, but only represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0052] The terms "first, second, third, etc." or similar terms such as module A, module B, module C, etc. in the specification and claims are only used to distinguish similar objects, and do not represent a specific order for the objects. It can be understood that, under the condition of permission, the specific order or sequence can be interchanged so that the embodiments of the present application described here can be implemented in an order other than that illustrated or described here.

[0053] In the above description, the reference numerals representing steps do not necessarily mean that the steps will be executed in this order. It may also include intermediate steps or be replaced by other steps. Under the condition of permission, the order of the front and back steps can be interchanged, or they can be executed simultaneously.

[0054] The term "comprising" as used in the description and claims should not be construed as limited to the content listed thereafter; it does not exclude other elements or steps. Therefore, it should be interpreted as specifying the presence of the stated features, wholes, steps or components, but does not exclude the presence or addition of one or more other features, wholes, steps or components and their groups. Thus, the expression "an apparatus comprising devices A and B" should not be limited to an apparatus consisting only of components A and B.

[0055] As used herein, "one embodiment" or "an embodiment" means that the specific features, structures, or characteristics described in connection with the embodiment are included in at least one embodiment of the present application. Thus, the phrases "in one embodiment" or "in an embodiment" that appear throughout this specification do not necessarily all refer to the same embodiment, but may. Additionally, in various embodiments of the present application, if there is no special indication and logical conflict, the terms and / or descriptions between different embodiments are consistent and can be cross-referenced, and the technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0056] Note that the above is only a preferred embodiment of the present application and the technical principles applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and various obvious changes, re-adjustments, and substitutions can be made by those skilled in the art without departing from the protection scope of the present application. Therefore, although the present application has been described in detail through the above embodiments, the present application is not limited to the above embodiments, and without departing from the concept of the present application, more other equivalent embodiments can be included, all of which fall within the protection scope of the present application.

Claims

1. An automatic antenna selection circuit based on a TDD communication system, characterized in that: It includes a radio frequency switch, a plurality of coupling detection circuits and a plurality of comparison circuits, wherein the plurality of coupling detection circuits at least include a first coupling detection circuit, a second coupling detection circuit and a third coupling detection circuit, and the plurality of comparison circuits at least include a first comparison circuit and a second comparison circuit; The first port of the first coupling detection circuit is connected to the TDD signal source, the second port is connected to the input end of the RF switch, and the third port is connected to the first input end of the first comparison circuit; The first port of the second coupling detection circuit is connected to the first output end of the radio frequency switch, the second port is connected to the first antenna, and the third port is connected to the first input end of the second comparison circuit; The first port of the third coupling detection circuit is connected to the second output end of the radio frequency switch, the second port is connected to the second antenna, and the third port is connected to the second input end of the second comparison circuit; The first input terminal of the first comparison circuit receives the first detection signal output by the first coupling detection circuit, and the second input terminal receives a reference signal. The first comparison circuit outputs an enable signal to the enable terminal of the second comparison circuit according to the comparison result between the first detection signal and the reference signal, so as to control the working state of the second comparison circuit; The first input end of the second comparison circuit receives the second detection signal output by the second coupling detection circuit, and the second input end receives the third detection signal output by the third coupling detection circuit. The second comparison circuit outputs a control signal to the RF switch according to the comparison result of the second detection signal and the third detection signal to control the switching of the RF switch.

2. The automatic antenna selection circuit according to claim 1, characterized in that: The radio frequency switch includes a single-pole multi-throw switch, a fixed end of the single-pole multi-throw switch is connected to the second port of the first coupling detection circuit, a first moving end of the single-pole multi-throw switch is connected to the first port of the second coupling detection circuit, and a second moving end of the single-pole multi-throw switch is connected to the first port of the third coupling detection circuit.

3. The automatic antenna selection circuit according to claim 1, characterized in that: The coupling detection circuit includes a microstrip line coupler, a detector and a low-pass filter; The microstrip line coupler is used to extract the received signal energy and output the coupled signal to the detector, which is used to convert the coupled signal into a DC level signal and output it after filtering through a low-pass filter.

4. The automatic antenna selection circuit according to claim 3, characterized in that: The detector includes a diode detector or a logarithmic detector.

5. The automatic antenna selection circuit according to claim 1, characterized in that: The comparison circuit includes a high-speed voltage comparator.

6. The automatic antenna selection circuit according to claim 1, characterized in that: The first coupling detection circuit is used to detect the state of the TDD signal source; When the TDD signal source is in a transmitting state, the first detection signal output by the first coupling detection circuit is higher than the reference signal, the first comparison circuit outputs a high-level enable signal, and the second comparison circuit does not work; When the TDD signal source is in a receiving state, the first detection signal output by the first coupling detection circuit is lower than the reference signal, the first comparison circuit outputs a low-level enable signal, and the second comparison circuit operates.

7. The automatic antenna selection circuit according to claim 1, characterized in that: The second coupling detection circuit is used to extract the signal strength of the first antenna and output a second detection signal, and the third coupling detection circuit is used to extract the signal strength of the second antenna and output a third detection signal; When the second comparison circuit is working, a control signal is output to the RF switch according to the comparison result of the second detection signal and the third detection signal. The control signal is used to control the RF switch to switch to an antenna with a stronger signal so that the TDD signal source communicates through the antenna with a stronger signal.

8. A TDD communication device, characterized in that: An automatic antenna selection circuit based on a TDD communication system comprising any one of claims 1 to 7.

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