CN102572861A - Polarization-diversity-gain-optimization-based polarization variation method for base station - Google Patents

Abstract

The invention provides a polarization-diversity-gain-optimization-based polarization variation method for a base station, and is applied in the field of wireless communication. The polarization state of an antenna comprises two degrees of freedom, namely a polarization angle alpha and a relative phase difference phi. A polarization gain optimization scheme based on the variation of an antenna mounting angle of the base station is disclosed by recent related researches; and according to the scheme, the degree of freedom relative phase difference phi of the polarization state is overlooked. Compared with the scheme, the embodiment of the invention jointly optimizes the polarization angle alpha and the relative phase difference phi corresponding to the polarization state of a transmitting antenna of the base station. The method in the embodiment of the invention comprises the following steps that: the base station estimates a channel to acquire the statistical characteristics of the channel; the base station establishes a diversity gain optimization target model according to the statistical characteristics of the channel and the transmission polarization state; the base station solves an optimal transmission polarization state (alpha*,phi*) by adopting a swarm-intelligence-based particle swarm optimization algorithm; and the base station realizes the polarization variation of the transmitting antenna according to the (alpha*,phi*). A simulation result shows that high polarization diversity gain can be obtained by jointly optimizing the polarization angle alpha and the relative phase difference phi corresponding to the polarization state of the transmitting antenna of the base station.

Description

Based on the optimum base station polarization method of polarization diversity gain

Technical field

The invention belongs to wireless communication field, particularly based on the optimum sending method of the optimum base station polarization of polarization diversity gain.

Background technology

At wireless communication field, the possibility that experiences deep fade owing to different polarization modes simultaneously is very little, and polarization diversity can obtain effective diversity gain.Present research about polarization diversity mainly concentrates on polarization diversity and the analysis and research of space diversity performance comparison, characteristics of radio channels dispose the aspects such as influence to polarization diversity gain to influence, transmission and the reception antenna of polarization diversity gain.The final goal of these researchs all is to improve polarization diversity gain.In order to improve polarization diversity gain, from the angle of receive diversity, existing research shows that ± 45 ° of dual polarized antenna diversity receptions are receive modes of quasi-optimal.In fact, the size of receiving terminal diversity gain is simultaneously also by the antenna polarization configuration decision of making a start.Correlative study in the recent period proposes a kind of based on the polarization gain optimization scheme that changes the antenna setting angle degree, through changing the antenna setting angle degree, promptly is equivalent to change antenna polarization angle α and makes the receiving terminal polarization diversity gain maximum.Yet a polarized state can be expressed as the Jones vector form $\left[\begin{array}{c}\mathrm{Cos}\mathrm{\α}\\ {\mathrm{Sin}\mathrm{\α\; e}}^{\mathrm{J\φ}}\end{array}\right],$ Promptly a polarized state has polarizing angle α and two degrees of freedom of relative phase difference φ.Polarization gain optimization scheme based on changing the antenna setting angle degree has been ignored this degree of freedom of polarized state relative phase difference φ, only is a special case of φ=0.Polarizing angle α and relative phase difference φ that combined optimization base station transmitting antenna polarized state is corresponding can obtain higher diversity gain.

Summary of the invention

In order to make the receiving terminal polarization diversity gain maximum; Instance of the present invention provides a kind of base station end to pass through channel estimating; Set up diversity gain optimum target model; Select the optimum of match channels statistical property to send polarized state through the swarm intelligence particle swarm optimization algorithm, realize the optimum polarization transmission of base station end, said technical scheme is following:

Based on the optimum base station polarization method of polarization diversity gain, comprising:

The base station estimates that channel obtains the channel statistical characteristic;

According to channel statistical characteristic and transmission polarized state, set up diversity gain optimum target model;

Adopt the swarm intelligence particle swarm optimization algorithm to find the solution the optimum polarized state of sending;

The polarization of transmitting antenna is realized in the base station.

The beneficial effect of the technical scheme that instance of the present invention provides is:

Through estimating the channel statistical characteristic, set up diversity gain optimum target model, find the solution optimum transmitting antenna polarized state, realize that antenna for base station adapts to the polarisation channel statistical property, the optimum emission of polarization makes the receiving terminal polarization diversity gain maximum.

Description of drawings

Fig. 1: the communication system emission block diagram of the embodiment of the invention;

Fig. 2: the communication system of the embodiment of the invention receives block diagram;

Fig. 3: the optimum polarized state of the embodiment of the invention is selected block diagram;

Fig. 4: the diversity gain effect contrast figure that the embodiment of the invention is brought;

Embodiment

For making the object of the invention, technical scheme and advantage clearer, embodiment of the present invention is done to describe in detail further below in conjunction with accompanying drawing.

Referring to Fig. 1:

Modulation 100: mobile communication adopts conventional modulated, like GMSK (GaussianFilteredMinimumShiftKeying) modulation of adopting among the digital cellular mobile communication GSM (Global System of Mobile communication).

Shunt 200: be divided into two-way to one road signal, as two copies of quadrature transmitting antenna.

Optimum polarized state selects 300: channel statistic property is estimated in the base station; Set up and receive polarization diversity gain optimization objective function and channel statistical characteristic, send the polarized state relation; Through the swarm intelligence particle swarm optimization algorithm; Select optimal antenna to send polarized state, adopt the polarization technical equivalences to change the antenna polarization state.

Digital-to-analogue conversion 400: realize that digital signal is to analog signal conversion.

Orthogonal Double poliarizing antenna emission 500: the Orthogonal Double poliarizing antenna realizes that as the hardware foundation of polarization signal passes through radio-frequency antenna to the receiving terminal radiation.

Referring to Fig. 2:

Dual polarized antenna receives 600: realize that radiofrequency signal receives to analog signal.

Analog-to-digital conversion 700: realize the conversion of analog signal to digital signal.

Divide set and 800: merge the diversity reception two paths of signals, its output signal is the weighted sum of each tributary signal.Optional branch set and mode comprise equal gain combining, select merging and high specific merging etc.

Demodulation 900: from the reception signal after minute set also, recover message.

In embodiments of the present invention, referring to Fig. 3, optimum polarized state selects 300 to comprise:

Channel estimating 301: the least square channel estimating based on training sequence is carried out in time domain in the base station, obtains the dual polarization channel statistic property.The dual polarization channel of a VH-VH (can be any Orthogonal Double poliarizing antenna, receive for easy analysis adopts the vertical-horizontal dual polarized antenna to send to the vertical-horizontal dual polarized antenna) can be expressed as $\left[\begin{array}{cc}{h}_{\mathrm{Vv}}& h_{\mathrm{Vh}}\\ h_{\mathrm{Hv}}& h_{\mathrm{Hh}}\end{array}\right],$

Represent main pole power ratio (CPR), embody the selectivity of wireless scatter channel environment for polarized state, u ∈ (0,1) is presented as that vertically polarized wave is more suitable for the transmission of actual wireless scatter channel.

represents cross polarization discrimination (XPD), embodies the unpolarizing of wireless scattering environments.υ 1=ε { h _Vv, h _Vh, υ 2=ε { h _Hv, h _HhBe respectively the transmission coefficient correlation that receiving terminal is vertical and horizontal antenna obtains.σ 1=ε { h _Vv, h _Hv, σ 1=ε { h _Vh, h _HhBe respectively the reception coefficient correlation that transmitting terminal is vertical and horizontal antenna obtains.δ 1=ε { h _Vv, h _Hh, δ 2=ε { h _Hv, h _VhThe interchannel coefficient correlation of representing orthogonal polarization to cause, it is relevant relevant with contrapolarization to be respectively main poleization.Along with improving constantly of dual polarized antenna manufacture craft, υ 1, and υ 2, and σ 1, and σ 2 is approaching with zero.Therefore,, obtain u through channel estimating, x, δ 1, and δ 2.

Optimization objective function modeling and optimum polarized state are found the solution the performance of 302: one reception diversity systems and are weighed through diversity gain, and diversity gain is by the difference power of the correlation of receive diversity signal, receive diversity signal two branch roads and divide set and algorithm to determine jointly.

If the polarized state of transmitting antenna does $\left[\begin{array}{c}\mathrm{Cos}\mathrm{\α}\\ {\mathrm{Sin}\mathrm{\α}\·e}^{\mathrm{J\φ}}\end{array}\right],$ The base station obtains the channel statistic property parameters u through channel estimating, x, and δ 1, and δ 2, and then the difference power Δ (dB) of receiving terminal two signals is:

$\mathrm{\Δ}=\mathrm{abs}\left[10\log \left(\frac{A+B}{A-B}\right)\right]---\left(2\right)$

A＝[1+(1+|δ1| ²*(u-1)*x)]*cos ²α+[|δ1| ²+u-|δ1| ²*u+u*x]*sin ²α

B＝[|δ1|*cos(φ-φ1)+|δ2|*u*x*cos(φ+φ2)]*sin(2α)

φ 1 is the phase place of δ 1, and φ 2 is the phase place of δ 2.

Correspondingly, the correlation of receiving terminal two signals is:

$\mathrm{\ρ}=\frac{\sqrt{C^2+D^2}}{\sqrt{A+B}\sqrt{A-B}}---\left(3\right)$

C＝[-1+(1+|δ1| ²*(u-1)*x)]*cos ²α+[-|δ1| ²*(u-1)+u-u*x]*sin ²α

D＝[-|δ1|*sin(φ-φ1)+|δ2|*u*x*sin(φ+φ2)]*sin(2α)

It is different to handle the diversity signal mode based on concrete receiving system, can select different branch set also, and what establish the diversity system employing here is that high specific merges mode.Then optimization diversity gain object module does

$\underset{{\mathrm{\α}}^{*},{\mathrm{\φ}}^{*}}{\arg \max }\left\{G_{\mathrm{div}(\max \mathrm{imal}\_\mathrm{ratio}\_\mathrm{combine})}(\mathrm{\ρ},\mathrm{\Δ})\right\}---\left(4\right)$

St.

$\left\{\begin{array}{c}\mathrm{\α}\∈[0,\mathrm{\π}/2]\\ \mathrm{\φ}\∈(\mathrm{0,2}\mathrm{\π}]\end{array}\right.$

Wherein, Δ and ρ are with reference to formula (2), (3).

According to formula (4), adopt the swarm intelligence particle cluster algorithm, population crowd several 40, iterations 100 and inertial factor W=0.7 are set, find the solution the globally optimal solution G of optimization objective function _{Div (max imal_ratio_combine)}, i.e. optimum transmitting antenna polarized state (α under this wireless channel statistical property ^*, φ ^*).

Polarization 303: arbitrary polarized state can be expressed as through the Jones vector $\left[\begin{array}{c}\mathrm{Cos}\mathrm{\α}\\ {\mathrm{Sin}\mathrm{\α}\·e}^{\mathrm{J\φ}}\end{array}\right].$ The Orthogonal Double poliarizing antenna is adopted in the base station, and the Jones vector that vertical polarized antenna is corresponding is expressed as $\left[\begin{array}{c}1\\ 0\end{array}\right],$ The Jones vector that horizontally-polarized antenna is corresponding is expressed as $\left[\begin{array}{c}0\\ 1\end{array}\right],$ So arbitrary polarized state can be characterized by the stack of perpendicular polarization and horizontal polarization.The polarization technology is exactly to carry two paths of signals corresponding amplitude and phase place through changing the Orthogonal Double poliarizing antenna, and equivalence changes the transmitting antenna polarized state.Send polarized state (α by optimization ^*, φ ^*) and shunting sign s (t), vertical polarized antenna sends ${\mathrm{Cos}\mathrm{\α}}^{*}\·\left[\begin{array}{c}1\\ 0\end{array}\right]\·s\left(t\right),$ Horizontally-polarized antenna sends ${\mathrm{Sin}\mathrm{\α}}^{*}\·e^{{\mathrm{J\φ}}^{*}}\·\left[\begin{array}{c}0\\ 1\end{array}\right]\·s\left(t\right),$ Be equivalent to the polarization transmitting antenna to (α ^*, φ ^*).

The diversity gain effect contrast figure that Fig. 4 brings for the embodiment of the invention.Choosing based on the polarization gain optimization scheme that changes the antenna setting angle degree is the contrast scheme, G _{Div (traditional)}Represent the polarization diversity gain that this scheme obtains, D _{Div (optimized)}The receiving terminal polarization diversity gain that the expression embodiment of the invention obtains.The diversity gain that brings for comparing embodiment promotes effect, and choosing two kinds of typical radio communication scene Urban_Macro (urban macro honeycomb) and Urban_Micro (urban district microcellulor), to carry out the performance simulation contrast as shown in Figure 4.Consider the different communication scene, correspondingly be provided with channel statistical characterisitic parameter u, x, δ 1; δ 2, and Fig. 4 shows that the base station has been considered relatively only to consider polarizing angle α after polarizing angle α and two degrees of freedom of relative phase difference φ; Polarization diversity gain is under the Urban_Macro scene, as channel relevancy δ 1=0.2, during δ 2=0.2; The embodiment scheme provides extra 0.8dB diversity gain, and as channel relevancy δ 1=0.2, δ 2=0.9 embodiment scheme can provide extra 2.15dB diversity gain; Under the Urban_Micro scene, as channel relevancy δ 1=0.2, during δ 2=0.2, the embodiment scheme provides extra 0.69dB diversity gain, and as channel relevancy δ 1=0.2, during δ 2=0.9, the embodiment scheme can provide extra 1.63dB diversity gain.Therefore, compare based on the polarization gain optimization scheme that changes the antenna setting angle degree, polarizing angle α and relative phase difference φ that combined optimization base station transmitting antenna polarized state is corresponding can obtain higher diversity gain.

Claims (2)

1. based on the optimum base station polarization method of polarization diversity gain, use and wireless communication field, it is characterized in that, comprising:

The base station estimates that channel obtains the channel statistical characteristic;

According to channel statistical characteristic and transmission polarized state, set up diversity gain optimum target model;

Adopt the swarm intelligence particle swarm optimization algorithm to find the solution the optimum polarized state of sending;

The polarization of transmitting antenna is realized in the base station.

2. method according to claim 1 is characterized in that, said according to the channel statistical characteristic with send polarized state, set up diversity gain optimum target model, comprising:

The least square channel estimating based on training sequence is carried out in time domain in the base station, obtains the dual polarization channel statistic property, comprises u, x, and δ 1, and δ 2;

Set up diversity gain optimum target model:

$\underset{\underset{0<\mathrm{\&phi;}\&le;2*\mathrm{\&pi;}}{0\&le;\mathrm{\&alpha;}\&le;\mathrm{\&pi;}/2}}{\max }\left\{G_{\mathrm{div}}(\mathrm{\&rho;},\mathrm{\&Delta;},\mathrm{\&kappa;})\right\}$

ρ＝f(u，x，δ1，δ2)

Δ＝g(u，x，δ1，δ2)

Wherein ρ is two diversity signal correlations, and Δ is the dB value of two diversity signal power ratios, branch set and the mode of κ for selecting

If the polarized state of transmitting antenna does $\left[\begin{array}{c}\mathrm{Cos}\mathrm{\&alpha;}\\ {\mathrm{Sin}\mathrm{\&alpha;}\&CenterDot;e}^{\mathrm{J\&phi;}}\end{array}\right],$ The base station obtains the channel statistic property parameters u through channel estimating, x, and δ 1, and δ 2, and then the difference power Δ (dB) of receiving terminal two signals is:

$\mathrm{\&Delta;}=\mathrm{abs}\left[10\log \left(\frac{A+B}{A-B}\right)\right]$

A＝[1+(1+|δ1| ²*(u-1)*x)]*cos ²α+[|δ1| ²+u-|δ1| ²*u+u*x]*sin ²α

B＝[|δ1|*cos(φ-φ1)+|δ2|*u*x*cos(φ+φ2)]*sin(2α)

φ 1 is the phase place of δ 1, and φ 2 is the phase place of δ 2.

Correspondingly, the correlation of receiving terminal two signals is:

$\mathrm{\&rho;}=\frac{\sqrt{C^2+D^2}}{\sqrt{A+B}\sqrt{A-B}}$

C＝[-1+(1+|δ1| ²*(u-1)*x)]*cos ²α+[-|δ1| ²*(u-1)+u-u*x]*sin ²α

D＝[-|δ1|*sin(φ-φ1)+|δ2|*u*x*sin(φ+φ2)]*sin(2α)

It is different to handle the diversity signal mode based on concrete receiving system, and κ can select different branch set also, and what establish the diversity system employing here is that high specific merges mode.Optimization diversity gain object module is:

$\underset{{\mathrm{\&alpha;}}^{*},{\mathrm{\&phi;}}^{*}}{\arg \max }\left\{G_{\mathrm{div}(\max \mathrm{imal}\_\mathrm{ratio}\_\mathrm{combine})}(\mathrm{\&rho;},\mathrm{\&Delta;})\right\}$

St.

$\left\{\begin{array}{c}\mathrm{\&alpha;}\&Element;[0,\mathrm{\&pi;}/2]\\ \mathrm{\&phi;}\&Element;(\mathrm{0,2}\mathrm{\&pi;}]\end{array}\right.$

Wherein, Δ and ρ are with reference to formula (2), (3).

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