阅读说明：本技术 一种主动式智能反射表面设计方法 (Active intelligent reflection surface design method ) 是由 梁应敞 龙睿哲 于 2020-03-30 设计创作，主要内容包括：本发明属于无线通信设备技术领域,具体涉及一种主动式智能反射表面设计方法。本发明采用M个基于负阻抗电路的反射单元构成智能反射表面,每个反射单元通过有源电路具备负阻抗特性,每个反射单元包含K个可选的负阻抗电路,反射单元通过开关改变接入负阻抗Z<Sub>L</Sub>来改变入射信号的相位与幅度的大小,通过改变负阻抗电路负载的电抗值,即可实现反射单元到天线阻抗的匹配。本发明的方法可用于各类通信系统中,通过对入射信号进行相位调整与幅度放大,极大地增强了入射信号的强度,从而提升无线通信的传输效率。(The invention belongs to the technical field of wireless communication equipment, and particularly relates to a design method of an active intelligent reflection surface. The invention adopts M reflection units based on negative impedance circuit to form an intelligent reflection surface, each reflection unit has negative impedance characteristic through an active circuit, each reflection unit comprises K selectable negative impedance circuits, and the reflection units change access negative impedance Z through switches L The phase and amplitude of the incident signal are changed, and the impedance value of the load of the negative impedance circuit is changed, so that the impedance of the antenna can be matched by the reflection unit. The method can be used in various communication systems, and greatly enhances the strength of the incident signal by carrying out phase adjustment and amplitude amplification on the incident signal, thereby improving the transmission efficiency of wireless communication.)

1. An active intelligent reflection surface design method is characterized in that M reflection units based on a negative impedance circuit are adopted to form an intelligent reflection surface, each reflection unit enables load impedance to have negative impedance characteristics by adding an active circuit, each reflection unit comprises K selectable negative impedance circuits, and the reflection units change access negative impedance Z through switches_LTo change the phase and amplitude of the incident signal, i.e. the reflection coefficient is:

wherein Z is_AIs the antenna impedance;

to the loading bias voltage of V_biasFor power P_inFrequency of f_inThe impedance value of the negative impedance circuit load is:

Z_L(f_in,V_bias,P_in)＝-R_L+jX_L,R_L>0

wherein, -R_LAnd X_LRespectively representing the resistance and reactance of a negative impedance circuit load, by varying the reactance of the negative impedance circuit load so that X_L＝-X_A，X_AThe equivalent reactance of the antenna is represented, i.e. the matching of the reflection unit to the antenna impedance can be achieved.

2. The method according to claim 1, wherein the active intelligent reflective surface is a reflective surface, the negative impedance circuit comprises a tunnel diode, a bias voltage, a bias capacitor, a bias inductor, a direct current filter capacitor, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6, one end of the first resistor R1 is connected with a switch, the other end of the first resistor R1 is connected with one end of the second resistor R2 through the direct current filter capacitor, the other end of the second resistor R2 is connected with the bias voltage after passing through the third resistor R3 and the bias inductor in sequence, a connection point of the second resistor R2 and the third resistor R3 is connected with the anode of the tunnel diode after passing through the fourth resistor R4 and the fifth resistor R6 in sequence, the cathode of the tunnel diode is grounded, and a connection point of the fourth resistor R4 and the fifth resistor R5 is grounded after passing through the sixth resistor R6 and the bias capacitor in sequence.

Technical Field

The invention belongs to the technical field of wireless communication equipment, and particularly relates to a design method of an active intelligent reflection surface.

Background

With the explosive development of the mobile internet and the internet of things, the future communication network faces the huge traffic and huge connection challenges brought by the continuous growth of equipment. In particular, in the 6G new vision, the communication network needs to implement ultra-massive traffic communication at Tbps level, and ultra-massive connection communication supporting tens of terminals per square meter. There is a need for a new transmission technique that achieves high spectral efficiency and energy efficiency.

In recent years, intelligent reflective surfaces can deploy multiple reflective units to intelligently reprogram wireless channels, thereby improving the transmission quality of signals. Because the arrangement is simple and complex active radio frequency circuit devices such as a digital-to-analog converter, an oscillator, an up-converter, a power amplifier and the like are not needed, the intelligent reflective surface communication is regarded as a next-generation communication technology with high spectral efficiency and high energy efficiency.

The traditional intelligent reflection surface communication system needs to be provided with a large-scale passive reflection unit to solve the problems of weak self reflection capability, large path loss and the like, so that the circuit cost, the space cost and the energy consumption cost are greatly improved. The active reflection unit based on the negative impedance design can reflect and amplify incident signals by introducing the active circuit, so that the self reflection capability is greatly improved, and the signal transmission efficiency is improved. Existing active reflection units have been widely used in reflective communication systems to increase the transmission range of the system. The intelligent reflective communication system can further improve the signal transmission performance by utilizing the active reflection unit, thereby improving the frequency spectrum utilization efficiency.

Disclosure of Invention

In view of the above problems, the present invention provides a method for designing an active intelligent reflective surface communication device based on negative impedance, and the active intelligent reflective surface device of the present invention can be used for assisting wireless communication signal transmission, thereby further improving the spectrum efficiency and energy efficiency of a wireless communication system. Specifically, in the active intelligent reflection surface, each independent reflection unit can realize negative impedance characteristics by using an active circuit, and phase adjustment is performed on incident signals so that multiple paths of reflection signals are mutually enhanced or cancelled at a receiver, and meanwhile amplitude amplification is performed on the incident signals.

The technical scheme adopted by the invention is as follows:

an active intelligent reflection surface design method adopts M reflection units based on a negative impedance circuit to form an intelligent reflection surface, each reflection unit has a negative impedance characteristic through an active circuit, each reflection unit comprises K selectable negative impedance circuits, and the reflection units change access negative impedance Z through switches_LTo change the phase and amplitude of the incident signal, i.e. the reflection coefficient is:

wherein Z is_AIs the antenna impedance; reflection unit with non-linear calculation based on positive impedance design²The invention introduces a negative impedance load into the reflection unit of the intelligent reflection surface, thereby realizing the reflection amplification of the incident signal.

To the loading bias voltage of V_biasFor power P_inFrequency of f_inThe impedance value of the negative impedance circuit load is:

Z_L(f_in,V_bias,P_in)＝-R_L+jX_L,R_L>0

wherein, -R_LAnd X_LRespectively representing the resistance and reactance of a negative impedance circuit load, by varying the reactance of the negative impedance circuit load so that X_L＝-X_A，X_AThe equivalent reactance of the antenna is represented, i.e. the matching of the reflection unit to the antenna impedance can be achieved.

Considering the antenna resistance as having Z_A＝R_A+jX_AFor a negative impedance reflecting element, the reflection coefficient is

As can be seen from the above equation, the magnitude of the reflection coefficient is greater than 1, so that the reflection unit based on the negative impedance can achieve amplification of the incident signal. The negative impedance load mentioned above can be realized by a tunnel diode and an active device such as a Complementary Metal Oxide Semiconductor (CMOS).

As a preferable mode, in the scheme of the present invention, the negative impedance circuit is constructed based on a tunnel diode, and includes a tunnel diode, a bias voltage, a bias capacitor, a bias inductor, a dc filter capacitor, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6, one end of the first resistor R1 is connected to the switch, the other end of the first resistor R1 is connected to one end of the second resistor R2 through the dc filter capacitor, the other end of the second resistor R2 is connected to the bias voltage through the third resistor R3 and the bias inductor in sequence, a connection point between the second resistor R2 and the third resistor R3 is connected to an anode of the tunnel diode through the fourth resistor R4 and the fifth resistor R6 in sequence, a cathode of the tunnel diode is grounded, and a connection point between the fourth resistor R4 and the fifth resistor R5 is connected to the ground through the sixth resistor R6 and the bias capacitor in sequence.

The active intelligent reflection surface equipment has the beneficial effects that the active intelligent reflection surface equipment can be used in various communication systems, and the equipment greatly enhances the intensity of incident signals by carrying out phase adjustment and amplitude amplification on the incident signals, so that the transmission efficiency of wireless communication is improved. The scheme is simple to implement, can prove to be capable of realizing transmission efficiency higher than that of a communication system without active intelligent surface assistance, and has strong application value.

Drawings

FIG. 1 illustrates an active intelligent reflective surface apparatus configuration of the present invention;

FIG. 2 shows a block diagram of a negative impedance implementation proposed by the present invention;

figure 3 illustrates an active intelligent reflective surface assisted wireless communication system contemplated by the present invention;

figure 4 shows a performance curve of signal-to-noise ratio versus reflection unit amplitude for an active intelligent reflective surface assisted wireless communication system contemplated by the present invention.

Detailed Description

The invention is described in detail below with reference to the following figures and examples:

take an active intelligent reflective surface based on negative impedance as an example. As shown in FIG. 1, the present invention contemplates the deployment of M (M ≧ 1) negative-impedance-based reflective units on an active intelligent reflective surface device; each reflecting unit has K (K is more than or equal to 1) load impedances (including negative impedance) which can be selected; the negative impedance can be implemented by a tunnel diode based circuit as shown in fig. 2 (the negative impedance implements the circuit in a variety of ways, only one of which is the tunnel diode circuit implementation). In the circuit of FIG. 2, C_dcIs a DC filter capacitor, C_biasTo bias capacitance, L_biasFor biasing the inductance, V_biasIs a bias voltage, R_i1.. 6 is a resistor, and the overall circuit impedance Z can be made by designing a specific resistance value_LMatching the antenna resistance.

Based on the active intelligent reflective surface apparatus designed in fig. 1, the present invention takes the following active intelligent reflective surface assisted communication system as an example to further describe the performance and the available method of the active intelligent reflective surface in detail.

As shown in FIG. 3, the communication system assisted by an active intelligent reflective surface is considered in the present invention, wherein M (M ≧ 1) reflective units based on negative impedance are deployed in the active intelligent reflective surface device, and both the transmitter and the receiver are single antennas. Assuming that the transmitter transmission signal s (n) is a signal with zero mean variance 1 and the transmission power is p_t. The receiver signal y (n) can be expressed as follows

Wherein the content of the first and second substances,representing a direct link channel from the sender to the receiver,representing the channel from the transmitter to the intelligent reflective surface device,representing the intelligent reflective surface device to receiver channel, which together constitute the intelligent reflective surface auxiliary channel;is a diagonal matrix of reflection coefficients of the intelligent reflective surface, where_m∈{₁,₂,...,_KM is 1, M denotes a reflection coefficient of the M-th reflection unit, and the reflection coefficient is_kCan be selected by switching its switch on the impedance load via the reflection unitAnd (5) realizing. For convenience, each reflection coefficient may be expressed asa_mAnd theta_mThe amplitude and the phase of the mth reflection coefficient are represented, and for the active intelligent reflection surface equipment, the amplitude of the reflection coefficient can be larger than 1;andrespectively representing Gaussian white noise vectors introduced into a receiver and an intelligent reflecting surface device, and covariance matrixes of the Gaussian white noise vectors are respectivelyAnd andrespectively represents the noise power of the received signal at the receiver and the active intelligent reflecting surface, and (I represents an identity matrix).

The received signal-to-noise ratio at the receiver is:

simulation results are given below to verify the effectiveness of the active intelligent reflective surface design described above. We consider an emulation design where the active intelligent reflective surface has M-1 and the channel gain has a value of h₁|²＝0.2|h₂|²＝0.5，|g|²0.8, and the phase of the reflection unit of the intelligent reflection surface has theta arg (h)₁)-arg(h₂) -arg (g) wherein arg () represents a phase angle taking operation. The phase selection may be such that the signal of the intelligent reflective auxiliary link is added in phase with the signal of the direct link. Taking into account the signal-to-noise ratio of the transmission

Fig. 4 compares the influence curve of the design of the active intelligent reflective surface on the signal-to-noise ratio of the wireless communication under the condition of changing the amplitude of the reflective unit. It can be seen that the design (a ═ a) is designed at the optimum amplitude, compared to the case without active smart reflective surface (a ═ 0) and with passive smart reflective surface (a ═ 1) only^*) In the following, the active intelligent reflection surface provided by the invention can provide better signal-to-noise ratio improvement. Therefore, the design of the active intelligent reflection surface provided by the invention has strong practical value and improves the transmission performance of the auxiliary communication system.