CN104468430A - Channel parameter evaluation method for IQ imbalance type OFDM system receiver - Google Patents

Abstract

The invention discloses a channel parameter evaluation method for an IQ imbalance type OFDM system receiver. A signal estimation module of the OFDM system receiver is composed of a special pilot frequency structure. According to the channel parameter evaluation method for the IQ imbalance type OFDM system receiver, based on the pilot frequency design, the special pilot frequency structure composed of two OFDM symbols is designed, a time domain LS method based on the special pilot frequency is provided, the frequency utilization rate is extremely high, and the number of OFDM training symbols is greatly reduced.

Description

The unbalanced channel parameter estimation method of ofdm system receiver IQ

Technical field

The present invention relates to wireless communication field, particularly the unbalanced channel parameter estimation method of a kind of ofdm system receiver IQ.

Background technology

OFDM (OFDM, Orthogonal frequency division multiplexing) be a kind of multi-carrier modulation technology, the availability of frequency spectrum is higher, and the ability of anti-multipath jamming is stronger, become one of key technology of wireless mobile communications of future generation, and in ofdm system, channel parameter estimation method becomes one of focus of Chinese scholars research.

But channel conditions in wireless communications is quite complicated, radio wave is subject to the impact of the circulation ways such as reflection, refraction and scattering in transmitting procedure because of the uneven meeting of transmission medium, and the relative motion between mobile terminal can cause Doppler effect, these factors all can cause the decline of signal in transmitting procedure.In addition, mobile radio terminal is just towards portable, low in energy consumption, that price is low future development, zero intermediate frequency reciver compared with price superheterodyne receiver and power consumption all lower, therefore the design of future wireless system terminal receiver can develop towards zero intermediate frequency reciver, but it is faced with the problem affected by I road and Q road amplitude, unbalance in phase, and this can cause the decline of systematic function.

Therefore, a kind of new method is needed to solve the unbalanced channel parameter estimation problem of IQ in ofdm system receiver.

Summary of the invention

Technical problem to be solved by this invention is the defect for background technology, provides the unbalanced channel parameter estimation method of a kind of ofdm system receiver IQ, significantly to reduce OFDM training symbol number, improves band efficiency.

The present invention is for solving the problems of the technologies described above by the following technical solutions.First, the special training structure of two OFDM symbol compositions is constructed.Then, two training symbols, through multipath channel, obtain two corresponding frequency-domain received signal.Then, according to frequency domain LS method of estimation, calculate LS and estimate.For excavating its time domain specification, frequency-region signal is transformed into time domain.Finally, time-domain received signal is transformed into frequency domain.

The present invention adopts above technical scheme compared with prior art, has following technique effect:

The unbalanced channel parameter estimation method of ofdm system receiver IQ adopted, from the design of pilot tone, devise a kind of Special Pilot-aided structure be made up of two OFDM symbol, propose the time domain LS method based on Special Pilot-aided, frequency efficiency is high, and significantly reduces OFDM training symbol number.

The aspect that the present invention adds and advantage will part provide in the following description, and these will become obvious from the following description, or be recognized by practice of the present invention.

Accompanying drawing explanation

Fig. 1 is flow chart according to an embodiment of the invention.

Embodiment

Below in conjunction with the drawings and specific embodiments, illustrate the present invention further, these embodiments should be understood only be not used in for illustration of the present invention and limit the scope of the invention, after having read the present invention, the amendment of those skilled in the art to the various equivalent form of value of the present invention has all fallen within the application's claims limited range.

The unbalanced channel parameter estimation method of a kind of ofdm system receiver IQ of the present invention comprises: the channel parameter estimation method of ofdm system receiver is estimated based on the time domain LS of Special Pilot-aided, and described pilot configuration is made up of two OFDM symbol.

Preferably, the time domain LS method of estimation based on Special Pilot-aided comprises following five steps.

The first step, construct the special training structure of two OFDM symbol compositions, described structure is as follows:

$s_1=\left(\begin{array}{c}\mathrm{\η}\\ s_p\\ \mathrm{\η}\\ 0_{(N/2-1)\×1}\end{array}\right),s_2=\left(\begin{array}{c}\mathrm{j\η}\\ 0_{(N/2-1)\×1}\\ \mathrm{j\η}\\ s_p\end{array}\right)$

Wherein, represent the average power of transmission signal planisphere, s _pthe pilot signal that (N/2-1) × 1 is tieed up, and $\mathrm{tr}\left\{E\left(s_p{s}_p^H\right)\right\}=(N-1){\stackrel{\‾}{P}}_s.$

Second step, two training symbols, after multipath channel, can obtain two corresponding frequency-domain received signal:

${\tilde{z}}_a={\tilde{s}}_p\left(\mathrm{\μH}\right)+{\tilde{w}}_a,{\tilde{z}}_b=\mathrm{diag}\left\{v^{*}H\right\}{\widetilde{\stackrel{.}{s}}}_p^{\#}+{\tilde{w}}_b^{\#}$

Wherein, ${\tilde{s}}_p=\mathrm{diag}\left\{\begin{array}{c}\mathrm{\η}\\ s_p\\ \mathrm{\η}\\ s_p\end{array}\right\},{\tilde{w}}_a=\left(\begin{array}{c}-0.5j{w}_2\left(1\right)+0.5w_1\left(1\right)\\ w_1(2:N/2)\\ -0.5j{w}_2(N/2+1)+0.5w_1(N/2+1)\\ w_2(N/2+2:N)\end{array}\right),$ μ＝cos(θ/2)+jαsin(θ/2)，

${\widetilde{\stackrel{.}{s}}}_p=\mathrm{diag}\left(\begin{array}{c}\mathrm{\η}\\ {\stackrel{.}{s}}_p\\ \mathrm{\η}\\ {\stackrel{.}{s}}_p\end{array}\right),{\tilde{w}}_b=\left(\begin{array}{c}-0.5j{w}_2\left(1\right)+0.5w_1\left(1\right)\\ w_1(2:N/2)\\ -0.5j{w}_2(N/2+1)+0.5w_1(N/2+1)\\ w_2(N/2+2:N)\end{array}\right),$ ν＝αcos(θ/2)-jsin(θ/2)，

$H=F\left(\begin{array}{c}h\\ 0_{(N-L-1)\×1}\end{array}\right),$ F is normalization Fourier transform matrix, and α, θ are phase unbalance degrees; Superscript notation # is defined as:

3rd step, according to frequency domain LS method of estimation, calculates LS and is estimated as:

4th step, for excavating its time domain specification, frequency-region signal being transformed into time domain is:

5th step, then time-domain received signal is converted to frequency domain and is:

The present invention is from the design of pilot tone, and devise a kind of Special Pilot-aided structure of two OFDM symbol composition, propose the time domain LS method based on Special Pilot-aided, frequency efficiency is high, and significantly reduces OFDM training symbol number.

Claims (3)

1. the unbalanced channel parameter estimation method of ofdm system receiver IQ, is characterized in that: the channel parameter estimation method of ofdm system receiver is estimated based on the time domain LS of Special Pilot-aided, and described pilot configuration is made up of two OFDM symbol.

2. the unbalanced channel parameter estimation method of ofdm system receiver IQ according to claim 1, is characterized in that: the time domain LS method of estimation concrete steps based on Special Pilot-aided are as follows:

Step 1), construct the special training structure of two OFDM symbol compositions;

Step 2), two training symbols, through multipath channel, obtain two corresponding frequency-domain received signal;

Step 3), according to frequency domain LS method of estimation, calculate LS and estimate;

Step 4), for excavating its time domain specification, frequency-region signal is transformed into time domain;

Step 5), time-domain received signal is transformed into frequency domain.

3. the unbalanced channel parameter estimation method of ofdm system receiver IQ according to claim 2, it is characterized in that: based on the time domain LS method of estimation of Special Pilot-aided, its training structure is only made up of two OFDM symbol, and structure is as follows:

$s_1=\left(\begin{array}{c}\mathrm{\η}\\ s_p\\ \mathrm{\η}\\ 0_{(N-2-1)\×1}\end{array}\right),s_2=\left(\begin{array}{c}\mathrm{j\η}\\ 0_{(N/2-1)\×}\\ \mathrm{j\η}\\ s_p\end{array}\right)$

Wherein, represent the average power of transmission signal planisphere, s _pthe pilot signal that (N/2-1) × 1 is tieed up, and $\mathrm{tr}\left\{E\left(s_p{s}_p^H\right)\right\}=(N-1){\stackrel{\‾}{P}}_s.$