CN106102156A - Linearisation transmission method based on multiple antennas - Google Patents

Abstract

The present invention relates to wireless communication technology in order to solve existing power amplifier linearization technology higher and be not easily accomplished in engineering reality to the branch road coherence request of merit power amplifier, thus the problem affecting the quality of radio communication.The present invention provides a kind of linearisation transmission method based on multiple antennas, comprise the steps: that transmitting terminal carries out signal decomposition to sent Broad-band Modulated Signal, after the Broad-band Modulated Signal of non-constant-envelope is decomposed into multichannel constant envelope signal, each road constant envelope signal is carried out respectively power amplification, and the signal corresponding transmission antenna respectively after amplifying is launched；After receiving terminal receives each road constant envelope signal respectively by multipath reception antenna, each road constant envelope signal carrying out power amplification, and linearly synthesizes amplifying Hou Ge road constant envelope signal, the quantity of described reception antenna is identical with the quantity of transmission antenna.The present invention is applicable to wireless communication system.

Description

Multi-antenna based linearization transmission method

technical field

The invention relates to wireless communication technology, in particular to the application of a power amplifier linearization technology based on multi-antenna and constant envelope decomposition in wireless communication.

Background technique

Modern wireless communication systems are developing in the direction of high speed, wide band, and intelligence, and the frequency band resources are becoming more and more tight. In order to accommodate more communication channels within a limited spectrum range and improve spectrum utilization, OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing) and MIMO (Multi- Input&Multi-Output, multiple input multiple output) and other key technologies. Among them, the MIMO multi-antenna technology enables signals to be transmitted and received through multiple antennas at the transmitting end and the receiving end, thereby improving communication quality. It can make full use of space resources and realize multiple transmissions and multiple receptions through multiple antennas without increasing spectrum resources and antenna transmission power. Under the circumstances, the channel capacity of the system can be doubled, showing obvious advantages. On the other hand, OFDM adopts carrier orthogonal technology, and the spectrum zero point of each carrier overlaps with the zero point of adjacent carriers, which reduces the interference between carriers and further improves the frequency band utilization compared with traditional FDMA. The signals transmitted by modern wireless communication systems have the characteristics of wide frequency band and peak-to-average ratio (the dynamic range of the signal envelope is large). When such broadband signals pass through nonlinear power amplifiers, serious in-band and out-of-band distortion will occur. Increases the bit error rate of the communication system and interferes with adjacent channels. Therefore, modern wireless communication systems put forward very high requirements on the linearity of RF power amplifiers, and it is of great practical significance to improve the linearity of power amplifiers while maintaining high efficiency as much as possible. RF power amplifier linearization technology has become a key technology in the next generation wireless communication system.

The traditional power amplifier linearization method is power back, that is, the input power of the power amplifier is backed back several dB from the 1dB compression point, so that the power amplifier works in a region far away from the 1dB compression point, thereby returning to the linear amplification region. However, the power back-off method reduces the utilization efficiency of the power supply of the power amplifier and increases heat dissipation. This method of sacrificing efficiency for linearity is not advisable in many applications, and when the power back-off reaches a certain level It will no longer be possible to improve the linearity of the power amplifier. Therefore, the power back-off method is not suitable for modern wireless communication systems that have high requirements on the linearity and efficiency of power amplifiers. Aiming at the problem of power amplifier linearization, a series of power amplifier linearization and efficiency enhancement technologies have been proposed, such as feed-forward technology, negative feedback technology, LINC (Linear Amplification with Nonlinear Components), pre-distortion technology, envelope tracking (Envelope Tracking, ET ) technology, Envelope Elimination and Restoration (EER) technology, Doherty technology, etc. However, the development of these PA linearization techniques still fall short of the requirements of broadband wireless communication. The new generation of wireless communication system adopts OFDM technology with high spectrum efficiency and MIMO multi-antenna technology. The MIMO transmitting device needs multiple power amplifiers to drive the antenna. The nonlinear characteristics of each antenna are different. The current mainstream power amplifier linearization technology is used. When there are many antennas (such as pre-distortion linearization technology, etc.), it is necessary to add a number of different additional components or devices. When there are many antennas, the overhead it brings is relatively large. In order to adapt to the development of next-generation mobile communication technology, power amplifier linearization technology also needs continuous development and innovation. How to combine the characteristics of the new generation of wireless communication technology, adapt to the needs of new communication technology, and further improve the efficiency and linearity of RF power amplifier is a key problem to be solved urgently.

LINC technology is a technology that has both efficiency enhancement and linearization functions. This technology first decomposes a non-constant envelope signal into two constant-envelope phase-modulated signals, and then uses two power amplifiers with the same characteristics to analyze the two signals. The two signals are amplified separately, and finally the amplified two signals are synthesized into a linearly amplified signal by a power combiner. LINC technology can use high-efficiency non-linear power amplifiers to amplify two-way signals with constant envelopes, and the power amplifiers can work near saturation. Theoretically speaking, using LINC technology can make the efficiency of the power amplifier reach 100%, but due to the limitation of the power combiner, the overall efficiency of the power amplifier system using LINC technology is not high, and the efficiency of the lossy Wilkinson power combiner is low. The lossless Chireix-Outphasing power combiner is more efficient, but its linearity is poor. In addition, LINC technology is very sensitive to the amplitude and phase imbalance errors of the two power amplifier branches, so the two power amplifier branches are required to be as consistent as possible, but these are not easy to achieve in engineering practice.

Contents of the invention

The purpose of the present invention is to solve the problem that the existing power amplifier linearization technology requires high branch consistency of the power amplifier, which is not easy to realize in engineering practice, thus affecting the quality of wireless communication.

In order to achieve the above object, the present invention provides a linearized transmission method based on multiple antennas, comprising the following steps:

Step 1, performing signal decomposition on the broadband modulation signal to be sent, decomposing the non-constant-envelope broadband modulation signal into multiple constant-envelope signals;

Step 2, power amplifying the constant envelope signals of each channel respectively, and transmitting the amplified constant envelope signals respectively corresponding to one transmitting antenna;

Step 3. After receiving the constant envelope signals of various channels through multiple receiving antennas, the power of each constant envelope signal is amplified, and the amplified constant envelope signals of various channels are linearly synthesized. The number of the receiving antennas Same as the number of transmit antennas.

Specifically, there are two constant-envelope signals, and there are two transmitting antennas and two receiving antennas respectively.

Specifically, the specific method for signal decomposition in step 1 is as follows:

The modulation signal is expressed as

x(t)=A(t)e ^jΦ(t)

Among them, x(t) represents the modulation signal, A(t) represents the modulation amplitude of the signal, Φ(t) represents the modulation phase of the signal,

The signal decomposition of x(t) is as follows,

$\begin{array}{c}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}\\ <span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>\end{array}$

Among them, r=max(A(t)), max(A(t)) represents the maximum amplitude value of x(t), θ(t) represents the phase difference between the decomposed signal and x(t), x ₁ ( t) and x ₂ (t) represent decomposed constant envelope signals.

Specifically, in step 3, digital signal processing is used to perform linear signal synthesis, and the specific method is as follows:

The two signals received are:

The resulting signal is:

Among them, α and β represent the attenuation factors of the received signals y ₁ (t) and y ₂ (t), respectively, and represent the phases of the received signals y ₁ (t) and y ₂ (t), respectively.

Preferably, the linear combination of signals in step 3 also includes performing amplitude and phase compensation on the two received constant envelope signals, even if α=β, The synthesized signal can be expressed as:

The beneficial effects of the present invention are:

1) The present invention does not need to perform power synthesis, but directly sends out two channels, and synthesizes in a digital signal processing manner at the receiving end, so that there is no problem of power synthesizer efficiency.

2) In the present invention, two power amplifiers are used to amplify the constant-envelope signal, which greatly reduces the requirement on the linearity of the power amplifier, and the power amplifier can work in a region close to saturation, and the efficiency of the power amplifier is very high.

3) in the present invention, after the two-way signals are sent respectively, the synthesis recovery of the signals is carried out at the receiving end, and the amplitude and phase problems of the two-way signals can be relatively easily completed by using digital signal processing, and the LINC technology is to combine the two It is difficult to calibrate and adjust the amplitude and phase of the RF analog signal, and the error has a great influence on the synthesized signal.

Description of drawings

FIG. 1 is a schematic diagram of the principle of a multi-antenna-based linearized transmission method according to an embodiment;

Fig. 2 is a schematic diagram of a signal constant envelope decomposition principle of an embodiment.

detailed description

The technical solution of the present invention is described in detail below.

The present invention aims at the problem that the existing power amplifier linearization technology requires high branch consistency of the power amplifier and is not easy to realize in engineering practice, thereby affecting the quality of wireless communication, and provides a linearization transmission method based on multiple antennas , including the following steps: the transmitting end decomposes the broadband modulation signal to be transmitted, decomposes the non-constant envelope broadband modulation signal into multiple constant envelope signals, and performs power amplification on each constant envelope signal respectively, and The amplified signals are respectively transmitted corresponding to one transmitting antenna; after the receiving end receives each constant envelope signal through multiple receiving antennas, the power of each constant envelope signal is amplified, and the amplified constant envelope signal Network signals are linearly synthesized, and the number of receiving antennas is the same as the number of sending antennas.

Example

Taking the dual-antenna transceiver as an example, as shown in Figure 1, at the signal transmitting end, the broadband signal x(t) to be transmitted needs to be decomposed first, and the broadband modulation signal with a non-constant envelope is decomposed into two constant-envelope signals , the two-way signals after signal decomposition pass through two power amplifiers and then are transmitted from the two antennas respectively. Since the decomposed signal is a constant envelope signal, the requirements for the linearity of the RF power amplifier are greatly reduced, and the RF power amplifier can work at the maximum power output point (near saturation), very high efficiency can be achieved.

At the receiving end, the constant-envelope signals received by the two antennas can be synthesized to obtain the broadband modulation signal at the sending end by adopting the reverse process of the sending end.

Figure 2 schematically shows that the modulation signal x(t) is decomposed into two constant envelope signals x ₁ (t) and x ₂ (t), and the modulation signal can be expressed as:

x(t)=A(t)e ^jΦ(t)

Among them, A(t) represents the modulation amplitude of the signal, Φ(t) represents the modulation phase of the signal, the radius of the outer circle in the figure is the maximum amplitude value of the signal x(t), which is max(A(t)), and the radius of the inner circle is half of the maximum magnitude value of x(t). Any modulation signal x(t) (its maximum amplitude value does not exceed the radius value max(A(t)) of the outer circle) can be used between two constant envelope signals x ₁ (t) and x ₂ (t) and to indicate that the amplitude of the two signals is selected as a constant value max(A(t))/2, and the phase difference with x(t) is θ(t), so the modulated signal can be expressed as:

$\begin{array}{c}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}\\ <span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>\end{array}$

in

r=max(A(t))

The two signals x ₁ (t) and x ₂ (t) obtained after decomposition are signals with constant amplitude, that is, modulated signals with constant envelope.

At the receiving end, due to the difference in amplitude and phase between the two signals sent and received after decomposition compared with the original signal (the performance of time difference), the received two signals are:

The resulting signal is:

The signal at the receiving end may have differences in amplitude and phase, and if no corresponding compensation is performed, the synthesized linear signal will be distorted.

The two received signals pass through different paths, so there may be differences in the amplitude of the signals. When the signal is synthesized, the signal amplitude needs to be compensated. Based on the amplitude of one of the signals, the other is adjusted by digital signal processing. The amplitude of the two signals can be adjusted and compensated easily; and the phase error can be compensated by sending a specific training signal.

Finally, after the received signal is compensated by the corresponding amplitude and phase, even if α=β, When , the synthesized signal can be expressed as:

That is, the linear synthesis of signals can be realized, where α and β represent the attenuation factors of the received signals y ₁ (t) and y ₂ (t), respectively, and represent the phases of the received signals y ₁ (t) and y ₂ (t), respectively.

The above is an exemplary description of the technical solution of the present invention by taking the dual-antenna transceiver as an example. Those skilled in the art should understand that, according to the above embodiments, the broadband modulation signal to be transmitted is decomposed into multiple constant-envelope signals (two-way The above situation) and the situation of transmitting and receiving through multiple antennas can also be realized without paying creative labor.

Claims (5)

1. linearisation transmission method based on multiple antennas, it is characterised in that comprise the steps:

Step one, carry out signal decomposition to sent Broad-band Modulated Signal, the Broad-band Modulated Signal of non-constant-envelope is decomposed For multichannel constant envelope signal；

Step 2, each road constant envelope signal is carried out respectively power amplification, and the constant envelope signal the most corresponding after amplifying Root transmission antenna is launched；

Step 3, received each road constant envelope signal respectively by multipath reception antenna after, each road constant envelope signal is carried out power Amplify, and linearly synthesize amplifying Hou Ge road constant envelope signal, the quantity of described reception antenna and the number of transmission antenna Measure identical.

2. linearisation transmission method based on multiple antennas as claimed in claim 1, it is characterised in that described constant envelope signal Quantity is two-way, and described transmitting antenna and reception antenna are respectively two.

3. linearisation transmission method based on double antenna as claimed in claim 2, it is characterised in that step one carries out signal and divides The concrete grammar solved is as follows:

Described modulated signal is expressed as

X (t)=A (t) e^jΦ(t)

Wherein, x (t) represents modulated signal, and A (t) represents the modulation amplitude of signal, and Φ (t) represents the phase modulation of signal,

X (t) is carried out signal decomposition as follows,

$\begin{array}{c}x\left(t\right)=x_1\left(t\right)+x_2\left(t\right)\\ =\frac{r}{2}{e}^{j\left(\mathrm{\&Phi;}\left(t\right)+\mathrm{\&theta;}\left(t\right)\right)}+\frac{r}{2}{e}^{j\left(\mathrm{\&Phi;}\left(t\right)-\mathrm{\&theta;}\left(t\right)\right)}\\ =\frac{r}{2}\left(e^{j\left(\mathrm{\&Phi;}\left(t\right)+\mathrm{\&theta;}\left(t\right)\right)}+e^{j\left(\mathrm{\&Phi;}\left(t\right)-\mathrm{\&theta;}\left(t\right)\right)}\right)\end{array}$

Wherein, r=max (A (t)), max (A (t)) represent the maximum amplitude value of x (t), and θ (t) represents the signal after decomposing and x The phase contrast of (t), x₁(t) and x₂T () represents the constant envelope signal after decomposing.

4. linearisation transmission method based on double antenna as claimed in claim 3, it is characterised in that use numeral in step 3 Signal processing mode carries out linearly synthesis, and concrete grammar is as follows:

The two paths of signals received is:

The signal of synthesis is:

Wherein, α and β represents reception signal y respectively₁(t) and y₂The decay factor of (t),AndRepresent respectively and receive signal y₁(t) And y₂The phase place of (t).

5. linearisation transmission method based on double antenna as claimed in claim 4, it is characterised in that step 3 carries out holding wire Property synthesis time also include to receive two-way constant envelope signal carry out amplitude and phase compensation, even if α=β,Synthesis Signal can be expressed as