CN1645762A - Power controlling method for frequency-selective single carrier partitional transmitting system - Google Patents

Abstract

The method includes following steps: 1) after the communication between transmission and reception end is build up, the reception end figures out the relevant balanced SNR according to modulation mode and error rate; 2) the reception end selects the available subchannel based on the message of channel state, at the time of ensuring the balanced SNR, figures out the required reception SNR, and then figures out the signal power required by transmit end according to the reception SNR of reception end and link consumption; the power value of transmitting signal is defined as control message of power PT, and is fed back to the transmit end through feedback channel; 3) the transmit end adjusts the transmitting power and signal based on the received power control message and label information of subchannel.

Description

Poewr control method in the selecting frequency single carrier wave blocking transmission system

(1) technical field

The present invention relates to wideband digital communications method.Belong to the broadband wireless communication technique field.

(2) background technology

The communication technology has obtained tremendous development since nearest decades, particularly nineteen nineties, people's daily life and development and national economy have been produced far-reaching influence.And the future communications technology is just developing towards the direction of broadband high-speed, therefore many wideband digital transmission technologys are subjected to paying close attention to widely, the single carrier of OFDM (hereinafter to be referred as OFDM:Orthogonal FrequencyDivision Multiplexing) and frequency domain equalization (hereinafter to be referred as SC-FDE:Single Carrier withFrequency Domain Equalization) is exactly two kinds of wideband digital transmission technologys of being paid attention to by people, they all belong to the piecemeal transmission technology, and the degree that present OFDM is paid close attention to will be considerably beyond SC-FDE, and in multiple standards, become support technology, for example: the IEEE802.11a in the WLAN (wireless local area network) (WLAN:Wireless Local Area Network), the HiperLAN/2 of ETSI (ETSI:European Telecommunication Standard Institute), the IEEE802.16 in the wireless MAN (WMAN:Wireless Metropolitan Area Network); Various high-speed digital subscriber lines (xDSL:Digital Subscriber Line) in the cable data transmission all are based on the standard of OFDM technology.SC-FDE is not adopted by these standards, just is the physical layer transmission technology with the common suggestion of OFDM in IEEE802.16.

OFDM is a kind of multi-carrier transmission technology, and it is divided into N parallel mutually orthogonal narrowband subchannels to whole broad-band channel with N subcarrier.Ofdm system has many noticeable advantages: 1. very high spectrum efficiency; 2. realize fairly simple; 3. anti-multipath interference performance and anti-fading ability are strong; 4. can utilize channel condition information (being self adaptation OFDM technology) further to improve spectrum efficiency or the like.

Self adaptation OFDM technology can be utilized channel condition information, signal transmitting power is changed with the variation of channel situation, promptly certain at the biography code check, and satisfy under certain error rate requirement situation, make the total emission power minimum, thereby realize power control, reduce transmitted power as far as possible, improve power utilization.

These advantages make OFDM become the research focus over past ten years just, so that are considered to the support technology of future communications, particularly broadband wireless communications.But many shortcomings of ofdm system self, particularly its peak-to-average power is more excessive than (being called for short PAPR:Peakto Average Power Ratio), limiting its practical paces, and existing SC-FDE has above-mentioned all advantages except that the 4th of OFDM, and the PAPR problem that does not have OFDM, performance and efficient are suitable substantially with OFDM.It is people's development on the basis of research OFDM, this SC-FDE system equally takes the piecemeal transmission with OFDM, and adopt CP (if adopt zero padding (being called for short ZP:Zero Padding) mode, and with the be added to front of this frame of every frame hangover, then identical) with the CP effect, so just can be converted into circular convolution to the linear convolution of signal and channel impulse response, and eliminate the inter-frame-interference that multipath causes.And adopt simple frequency-domain equalization technology just can eliminate intersymbol interference at receiving terminal, for example: balanced and least mean-square error (the being called for short MMSE:Minimum Mean Square Error) equilibrium of ZF (being called for short ZF:Zero Forcing).

The SC-FDE system compares with OFDM, does not have the PAPR problem.And being ofdm system itself, the PAPR problem is difficult to the problem that solves with low-cost (spectrum efficiency and power efficiency) mode.Therefore the SC-FDE technology is subjected to increasing attention at present.Simply introduce the Mathematical Modeling of traditional SC-FDE system below.

The SC-FDE system is s (n) at the frame time-domain signal that transmitting terminal sends, (n=0,1,, N-1), pass through time-variant multipath channel, the impulse response of channel is h (n), (n=0,1, L-1), be subjected to the interference of additive white Gaussian noise (AWGN:AdditiveWhite Gaussian Noise) in the signals transmission, establishing noise is w (n), (n=0,1 ... N-1), remove after the CP, the time-domain signal r (n) that receives is:

r(n)＝s(n)h(n)+w(n)，(n＝0，1，…，N-1) (1)

Wherein, "  " expression circular convolution computing.

At receiving terminal signal is done discrete Fourier transform (DFT) (hereinafter to be referred as DFT:Discrete Fourier Transform) and transform to frequency domain, according to the time domain convolution theorem of DFT, resulting frequency-region signal is

R(k)＝S(k)·H(k)+W(k)，(k＝0，1，…，N-1) (2)

Wherein, R (k), S (k), H (k), W (k) they are respectively r (n), s (n), h (n), w (n) does the frequency domain symbol of N point DFT, and, H (k), (k=0,1 ..., N-1) be the frequency domain response of channel.Through the later frequency-region signal of zero forcing equalization be

$\tilde{S}\left(k\right)=S\left(k\right)+\frac{W\left(k\right)}{H\left(k\right)}=S\left(k\right)+\tilde{W}\left(k\right),(k=\mathrm{0,1},\·\·\·,N-1)----\left(3\right)$

At last, signal is done inverse discrete Fourier transform (hereinafter to be referred as IDFT:Inverse Discrete Fourier Transform) become time domain again and adjudicate, obtain the data of transmitting terminal transmission.

From (3) formula as can be seen, the signal that finally obtains is compared with the actual signal of transmission and is had error, and this error is caused by noise, especially exists under the situation about declining deeply a little at channel and can too amplify noise, can make signal produce distortion when in addition, using MMSE balanced.If utilized channel condition information in the SC-FDE system, these problems just obtain alleviating.Therefore, the applicant has proposed a kind of single carrier block transmission method of frequency selection method and (has applied for national inventing patent, number of patent application: 200410036439.6), overcome the shortcoming that traditional SC-FDE system can not utilize channel condition information, this new SC-FDE system has higher systematic function and efficient.

The performing step of the single carrier block transmission method of this frequency selection method is divided into:

The first step is found out available subchannels, and whether channel be can be used as mark, then the subchannel label information is sent to transmitting terminal by backward channel

The channel condition information H (k) that the receiving terminal basis estimates, (k=0,1 ..., N-1), from N subchannel, (the individual available subchannels of M≤N), the label of establishing this M available subchannels is k to select M from big to small according to amplitude gain _i(i=0,1 ..., M-1), and with remaining subchannel forbidding, use 1 bit information, promptly each subchannel of " 0 " or one token is available or unavailable, Here it is the needed subchannel label information of transmitting terminal, if receiving terminal is made the DFT that N is ordered, promptly total N subchannel, the subchannel label information that feeds back to transmitting terminal has the N bit, then this N bit information is beamed back transmitting terminal by backward channel.

In second step, change signal spectrum according to the subchannel label information

After transmitting terminal receives that receiving terminal sends the subchannel label information of returning, just can come transmission signals with M available subchannels, like this to a frame M SC-FDE symbol s (n), (n=0,1 ..., M-1), make M point DFT and transform to frequency domain:

$S\left(i\right)=\underset{n=0}{\overset{M-1}{\mathrm{\Σ}}}s\left(n\right)e^{-j\frac{2\mathrm{\π}}{M}\mathrm{ni}},(i=\mathrm{0,1},\·\·\·,M-1)----\left(4\right)$

Just obtain the frequency-region signal that M is ordered, with the k that elects _i, (i=0,1 ..., M-1) individual available subchannels H (k _i), (i=0,1,, M-1) transmission i frequency-region signal S (i), (i=0,1 ..., M-1), promptly on the signal spectrum point of available subchannels correspondence, place and want frequency domain signal transmitted, and the signal spectrum point zero setting that will forbid the subchannel correspondence also can be filled some non-information datas, so just obtain the new frequency-region signal S ' of a frame (k), (k=0,1,, N-1), counting is N:

$S^{\′}\left(k\right)=\left\{\begin{array}{cc}S\left(i\right),& k=k_i\\ 0,& k\≠k_i\end{array}\right.,(k=\mathrm{0,1},\·\·\·,N-1)----\left(5\right)$

Then, to S ' (k), (k=0,1 ..., N-1) make N point IDFT:

$s^{\′}\left(n\right)=\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}{S}^{\′}\left(k\right)e^{j\frac{2\mathrm{\π}}{N}\mathrm{nk}},(n=\mathrm{0,1},\·\·\·,N-1)----\left(6\right)$

Become time-domain signal, IDFT counts and is greater than N during oversampling, HFS zero setting, this time-domain signal made D/A after, modulate again and send.

The 3rd step, select the signal that transmits on the available subchannels, then the signal of electing is carried out equilibrium, and conversion returns time domain and adjudicates, finally obtain the data of transmitting.

Receiving terminal receives signal, and the time domain discrete signal that removes behind the CP is:

r′(n)＝s′(n)h(n)+w(n)，(n＝0，1，…，N-1) (7)

It is made the DFT that N is ordered:

$R^{\′}\left(k\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{r}^{\′}\left(n\right)e^{-j\frac{2\mathrm{\π}}{N}\mathrm{nk}},(k=\mathrm{0,1},\·\·\·,N-1)----\left(8\right)$

And:

R ' (k)=(k) H (k)+W (k) of S ', (k=0,1 ..., N-1) (9) just can select M the signal R (k on the available subchannels according to the subchannel label information like this _i), (i=0,1 ..., M-1), then with available subchannels Parameter H (k in the channel condition information that estimates _i), (i=0,1 ..., M-1), the signal of electing is carried out equilibrium; Can select one of following three kinds of balanced ways:

1, zero forcing equalization,

2, least mean-square error equilibrium,

3, mixed equilibrium, promptly a part of subchannel zero forcing equalization, and another part subchannel is balanced with least mean-square error; With the zero forcing equalization is that example is described:

$\tilde{S}\left(k_i\right)=\frac{R\left(k_i\right)}{H\left(k_i\right)},(i=\mathrm{0,1},\·\·\·,M-1)----\left(10\right)$

Order

$\tilde{S}\left(i\right)=\tilde{S}\left(k_i\right),(i=\mathrm{0,1},\·\·\·,M-1)----\left(11\right)$

It is made the IDFT that M is ordered:

$\tilde{s}\left(n\right)=\frac{1}{M}\underset{i=0}{\overset{M-1}{\mathrm{\Σ}}}\tilde{S}\left(i\right)e^{j\frac{2\mathrm{\π}}{M}\mathrm{ni}},(n=\mathrm{0,1},\·\·\·,M-1)----\left(12\right)$

These group data are just adjudicated and can be recovered initial data.

(3) summary of the invention

The single carrier block transmission method of frequency selection method utilizes channel condition information, can avoid declining a little deeply to frequency selective fading channels, thereby significantly improve the performance of system.Communication system generally has certain error performance requirement, and the parameter of decision systems error performance is the balanced back signal to noise ratio that can obtain, the ratio of promptly balanced back signal power and noise power.Therefore the present invention proposes a kind of Poewr control method of the blocking transmission system based on frequency selection method, guaranteeing that balanced back signal to noise ratio satisfies under the situation of system's error performance requirement, reduce sending signal power as much as possible, can effectively save transmitted power.

The method of this power control may further comprise the steps:

(1) after receiving-transmitting sides was set up and communicated by letter, receiving terminal was the error rate according to modulation system with the systematic function that requires to reach, and calculated corresponding required balanced back signal to noise ratio, and promptly the ratio of signal power and noise power after the equilibrium is designated as SNR _Eq

(2) receiving terminal is chosen available subchannels according to the channel condition information that obtains, and is guaranteeing that balanced back signal to noise ratio is SNR _EqThe time, calculate required received signal to noise ratio, calculate the required signal power of making a start by received signal to noise ratio and link attenuation again, claim that this transmission signal power value is power control information P _T, send transmitting terminal to by feedback channel.

(3) transmitting terminal is regulated transmitted power according to the power control information and the subchannel label information that receive, sends signal.

Below above step is elaborated:

In (1) step, receiving terminal calculates required balanced back signal to noise ratio according to modulation system and the systematic function that requires to reach

By analysis, the SC-FDE system has very strong antijamming capability, when channel estimation errors and synchronous error can be ignored, after the receiving terminal equilibrium, multipath channel is equivalent to Gaussian channel, be equivalent to the interference that whole system only is subjected to white Gauss noise, adopt the different modulating mode to reach the needed signal to noise ratio of the requirement error rate in the Gaussian channel, be the required balanced back signal to noise ratio snr of this system _CqIts computational methods just can find in general textbook, for example John.G.Proakis shows, and (DigitalCommunications 4 for " digital communication " (the 4th edition) of being published by McGraw-Hill Cos (The McGraw-Hill Companies.Inc) ^ThEdition) 254-283 page or leaf; When considering channel estimation errors and synchronous error, can estimate the error range of real system and the signal to noise ratio of loss by measurement, at this moment the computational methods of loss signal to noise ratio can will suitably increase SNR with reference to relevant document _EqTo offset signal to noise ratio owing to these errors losses.

In (2) step, receiving terminal calculates the required signal power of transmitting terminal according to channel condition information and required balanced back signal to noise ratio and link attenuation, forms power control information

The balanced back signal to noise ratio decision systems error rate, and balanced back signal to noise ratio is by received signal to noise ratio and balanced way decision.The balanced way difference, balanced back signal power is just different with noise power, and the received signal to noise ratio that needs is also different, and received signal to noise ratio and the decision of link attenuation send signal power, it is also just different then to send signal power; Wherein, the measurements and calculations method of received signal to noise ratio can not be described at this with reference to pertinent literature, is example below with the zero forcing equalization, calculates to send signal power:

Suppose the bilateral power spectral density of white Gauss noise

The channel condition information H (k) that receiving terminal obtains according to channel estimating, (k=0,1 ..., N-1), (the individual available subchannels of M≤N), establishing M the subchannel subscript of choosing is k to select M from big to small according to amplitude gain _i, (i=0,1 ..., M-1), the channel gain of these subchannels is | H (k _i) |, (i=0,1 ..., M-1).The noise gross power of the every frame in then balanced back is:

${\mathrm{\&sigma;}}^2=E\left(\underset{i=0}{\overset{M-1}{\mathrm{\&Sigma;}}}{\left|\frac{N\left(k_i\right)}{H\left(k_i\right)}\right|}^2\right)=\frac{{\mathrm{<figure-callout\; id="0"\; label="N"\; filenames="A20051004231500112.png"\; state="\{\{state\}\}">N</figure-callout>}}_0}{2}\underset{i=0}{\overset{M-1}{\mathrm{\&Sigma;}}}{\left|\frac{1}{H\left(k_i\right)}\right|}^2\left(W\right)----\left(13\right)$

Known required balanced back signal to noise ratio is SNR _Eq, the required received signal power of then every frame is:

$P_R={\mathrm{\&sigma;}}^2\&CenterDot;{\mathrm{SNR}}_{\mathrm{eq}}=\frac{{\mathrm{<figure-callout\; id="0"\; label="N"\; filenames="A20051004231500112.png"\; state="\{\{state\}\}">N</figure-callout>}}_0}{2}\&CenterDot;{\mathrm{SNR}}_{\mathrm{eq}}\underset{i=0}{\overset{M-1}{\mathrm{\&Sigma;}}}{\left|\frac{1}{H\left(k_i\right)}\right|}^2\left(W\right)----\left(14\right)$

Consider the link attenuation, establishing the link attenuation is L, and then required transmission signal power is:

$P_T=\frac{P_R}{L}=\frac{{\mathrm{<figure-callout\; id="0"\; label="N"\; filenames="A20051004231500112.png"\; state="\{\{state\}\}">N</figure-callout>}}_0}{2}\&CenterDot;\frac{1}{L}\&CenterDot;{\mathrm{SNR}}_{\mathrm{eq}}\underset{i=0}{\overset{M-1}{\mathrm{\&Sigma;}}}{\left|\frac{1}{H\left(k_i\right)}\right|}^2\left(W\right)----\left(15\right)$

By feedback channel this performance number is formed power control information and pass to transmitting terminal.

In (3) step, transmitting terminal is regulated transmitted power according to the power control information and the subchannel label information that receive, chooses available subchannels, sends signal

Transmitting terminal makes to send the required transmission power value that gross power equals to feed back according to the power control information that receives, and sends signal; In actual applications, the transmitted power of system should be slightly larger than the transmission power value of feedback, leaves certain surplus, to guarantee the more stable of signal to noise ratio control, reaches system requirements.

The present invention is based on the blocking transmission system of frequency selection method, according to resulting channel condition information, by change to send after the equilibrium of signal power control receiving terminal signal to noise ratio be a definite value to control the error rate be a definite value, thereby realize control to the transmitting terminal signal power.Like this, change the power that sends signal, further improved power utilization according to the quality of channel status.

(4) description of drawings

Fig. 1 is a system block diagram of realizing method proposed by the invention.

Fig. 2 takes the 16QAM modulation system, chooses 208 available subchannels, and the control error rate is 10 ^-4The time the received signal to noise ratio curve.

Fig. 3 takes the 16QAM modulation system, chooses 208 available subchannels, and the control error rate is 10 ^-4The time emulation resulting error rate.

Among the figure: 1. information source module, 2. sign map module, 3.FFT module (M point), 4. signal spectrum conversion module, 5.IFFT module (N point), 6. power control module, 7. add Cyclic Prefix (CP) module, 8.D/A module, 9. intermediate frequency and rf modulations module, 10. channel, 11. radio frequency and intermediate frequency demodulation module, 12.A/D module, 13. go the CP module, 14. gain control module, 15.FFT module (N point), 16. the signal spectrum inverse transform block, 17. balance modules, 18.IFFT module (M point), 19. judging module, 20. channel estimating and signal power computing module, 21. synchronization modules, 22. backward channels

(5) embodiment

Embodiment:

Fig. 1 has provided the system block diagram of realizing method proposed by the invention, and each module effect is as follows:

Information source module 1: the data that generation will be transmitted.

Sign map module 2: when modulation system was selected QAM or MPSK, the data map that information source is produced was on the planisphere corresponding points.

M point FFT module 3: every frame M mapping signal is transformed to frequency domain, obtain the frequency-region signal that the M of signal is ordered.

Signal spectrum conversion module 4: send the subchannel label information of returning by backward channel 22 according to receiving terminal, the M point frequency-region signal of module 3 outputs is placed on the corresponding frequency spectrum point of M available subchannels, and the corresponding frequency spectrum point zero setting of forbidding subchannel, or fill non-information data, just obtain the new SC-FDE frequency-region signal of a frame N point.This module need (number of patent application: 200410036439.6) method of introducing be programmed, and is realized by the general digital signal processing chip according to the patent of invention of mentioning in the background technology.

N point IFFT module 5: the frequency-region signal that will newly obtain transforms to time domain again.

Power control module 6: regulate the transmission signal power according to the power control information that receives.

Add CP module 7: every frame data that will obtain add Cyclic Prefix.

D/A module 8: with digital signal conversion is analog signal.

Intermediate frequency and rf modulations module 9: if use this system under wireless environment, need make rf modulations to signal could the antennas emission.Need sometimes earlier signal to be modulated to carry out the intermediate frequency amplification on the intermediate frequency, remake rf modulations, at last the modulated signal antennas is launched.(for example: xDSL) use down this system, then do not need to do rf modulations, do not need antenna to transmit yet, but will move signal spectrum beyond the voice channel frequency band yet, guaranteeing does not influence speech transmissions in the transmission data if at cable environment.

Channel 10: the wire message way of transmission signals or wireless channel.

Synchronization module 21: the method by parameter Estimation (for example: blind estimation and based on the estimation of auxiliary data) obtains the various synchrodatas that system needs.Synchronization module is given radio frequency and intermediate frequency demodulation module 11 with the Frequency Synchronization data; Give analog-to-digital conversion module 12 with the sampling rate synchrodata; Regularly synchrodata is given CP module 13.

Radio frequency and intermediate frequency demodulation module 11: in wireless environment, the signal spectrum that reception antenna receives is moved low frequency from radio frequency or intermediate frequency.Before demodulation, need the frequency deviation that causes with in the Frequency Synchronization data correction signal transmission course.

A/D module 12: analog signal after the demodulation is transformed to digital signal.A/D need sample to analog signal, provides the crystal oscillator of clock signal need follow the crystal oscillator frequency of transmitter D/A module identical, otherwise will cause the sampling rate error.Therefore it is synchronous to carry out sampling rate before A/D.

Go CP module 13: Cyclic Prefix is removed.At this moment just have the problem of judging when frame data begin, therefore going needs to do regularly synchronously before the CP.

Gain control module 14:, eliminate the influence of power control to signal constellation point according to power control information.

N point FFT module 15: the signal transformation that will remove CP is to frequency domain.

Channel estimating and send signal power computing module 20: with syncsort seemingly, also need to obtain CSI blind Channel Estimation that commonly used generally is and based on the channel estimating of auxiliary data by parameter Estimation.Select available subchannels after estimating CSI, give balance module 17 these available subchannels parameters; Simultaneously whether available according to channel, with 1 bit information (" 0 " or " 1 ") mark, form the subchannel label information, give signal spectrum inverse transform block 16 and backward channel 22 simultaneously, beam back the signal spectrum conversion module 4 of transmitting terminal by backward channel the subchannel label information; Go out required transmission signal power according to reaching the required balanced back snr computation of the different error rates, pass to gain control module 14 and backward channel 22, beam back the power control module 6 of transmitting terminal by backward channel.The power control section branch of this module need be programmed according to the method that the present invention introduces, and is realized by the general digital signal processing chip.

Signal spectrum inverse transform block 16: according to channel estimating and send the subchannel label information that signal power computing module 20 is sent here, find out the M point frequency-region signal that carries by available subchannels in the received signal.This module need (number of patent application: 200410036439.6) method of introducing be programmed, and is realized by the general digital signal processing chip according to the patent of invention of mentioning in the background technology.

Balance module 17: with the available subchannels parameter that channel estimating and transmission signal power computing module 20 are sent here, the signal that signal spectrum inverse transform block 16 is elected carries out equilibrium.Balanced way can be selected one of following three kinds of balanced ways: zero forcing equalization, least mean-square error equilibrium, mixed equilibrium (that is: a part of subchannel zero forcing equalization, and the least mean-square error equilibrium of another part subchannel).

M point IFFT module 18: M frequency-region signal of signal after the equilibrium transformed to time domain.

Judging module 19: finish the judgement of time-domain signal according to planisphere.

Backward channel 22: subchannel label information and power control information are beamed back transmitting terminal.

When channel estimation errors and synchronous error can be ignored, after the receiving terminal equilibrium, multipath channel is equivalent to Gaussian channel, be equivalent to the interference that whole system only is subjected to white Gauss noise, adopt the different modulating mode to reach the needed signal to noise ratio of the requirement error rate in the Gaussian channel, be the required balanced back signal to noise ratio snr of this system _EqError rate calculation in the Gaussian channel can be shown with reference to John.G.Proakis, by " digital communication " (the 4th edition) (Digital Communications 4 of McGraw-Hill Cos (The McGraw-Hill Companies.Inc) publication ^ThEdition) the 278th page.

This embodiment simulation parameter:

Simulated environment: Matlab7.0

Subchannel sum: N=256

The available subchannels number, promptly every frame SC-FDE data symbol number: M=208.

CP length: 32

Sign map: 16QAM

The error rate of control is: 10 ^-4

Link attenuation: L=1 (be 0dB, do not consider the link attenuation here)

Synchronously and channel estimating: perfect estimation, promptly there are not error in synchronization parameter and channel estimation results

Under the situation of not considering link attenuation and synchronization parameter and channel estimation errors, can be illustrated more clearly in technique effect of the present invention.

Fig. 2 and Fig. 3 have provided the received signal to noise ratio curve of this embodiment of the present invention in 100 channel samples and the error rate situation of being controlled, wherein channel samples is taken from SUI-5 channel (one of test channel of advising in IEEE 802.16 standards), and wherein the unit of Fig. 2 signal to noise ratio snr is dB.From simulation result, as can be seen, through these 100 different channels samples the time, differ about 3.1dB (near the horizontal horizontal line among Fig. 2 the ordinate 18.65dB is represented the average received signal to noise ratio) between the maximum of received signal to noise ratio and the mean value.If do not take Poewr control method, system often sends signal power to guarantee to have stable error performance according to the worst channel conditions design.If this explanation system has adopted the Poewr control method can be than not adopting this method significantly to save power, the transmitting power that can save about 3.1dB under the Poewr control method of the present invention simulated conditions in the present embodiment.And what as can be seen from Figure 3 this embodiment can control the error rate is relatively stable.

For avoiding confusion, following explanation done in some nouns of being mentioned in this specification:

1. balanced back signal to noise ratio: signal power is with the ratio of noise power after balanced.

2. symbol: be meant the data of information bit after ovennodulation mapping (also claiming sign map).It generally is the plural number that a real part and imaginary part are integer.

3. a frame signal: for OFDM, a frame signal is meant N symbol doing the IFFT conversion at transmitting terminal, is meant at receiving terminal and is removing N the symbol that CP does the FFT conversion later on.For SC-FDE, a frame signal is meant N information symbol between adjacent two CP at transmitting terminal, is meant at receiving terminal and is removing N the symbol that CP does the FFT conversion later on.For the SC-FDE system that the method that proposes by the present invention realizes, a frame signal is meant M symbol doing the FFT conversion at transmitting terminal, is meant M symbol doing the IFFT conversion in equilibrium later at receiving terminal.

4. subchannel: for OFDM, the SC-FDE baseband signal, a subchannel is meant Frequency point behind receiving terminal FFT.For radio-frequency channel, a subchannel is meant one section frequency spectrum of radio-frequency channel.

Claims (4)

1. the Poewr control method in the selecting frequency single carrier wave blocking transmission system, it is characterized in that: the method for this power control may further comprise the steps:

(1) after receiving-transmitting sides was set up and communicated by letter, receiving terminal was the error rate according to modulation system with the systematic function that requires to reach, and calculated corresponding required balanced back signal to noise ratio, and promptly the ratio of signal power and noise power after the equilibrium is designated as SNReq;

(2) receiving terminal is chosen available subchannels according to the channel condition information that obtains, when guaranteeing that balanced back signal to noise ratio is SNReq, calculate required received signal to noise ratio, calculate the required signal power of making a start by received signal to noise ratio and link attenuation again, claim that this transmission signal power value is power control information P _T, send transmitting terminal to by feedback channel;

(3) transmitting terminal is regulated transmitted power according to the power control information and the subchannel label information that receive, sends signal.

2. the Poewr control method in the selecting frequency single carrier wave blocking transmission system according to claim 1, it is characterized in that: described step (1) adopts following method to realize: when channel estimation errors and synchronous error can be ignored, after the receiving terminal equilibrium, multipath channel is equivalent to Gaussian channel, be equivalent to the interference that whole system only is subjected to white Gauss noise, adopt the different modulating mode to reach the needed signal to noise ratio of the requirement error rate in the Gaussian channel, be the required balanced back signal to noise ratio snr of this system _EqWhen considering channel estimation errors and synchronous error, can estimate the error range of real system and the signal to noise ratio of loss by measurement, suitably increase SNR _EqTo offset signal to noise ratio owing to these errors losses.

3. the Poewr control method in the selecting frequency single carrier wave blocking transmission system according to claim 1, it is characterized in that: described step (2) adopts following method to realize: the balanced back signal to noise ratio decision systems error rate, and balanced back signal to noise ratio is by received signal to noise ratio and balanced way decision, the balanced way difference, balanced back signal power is just different with noise power, the received signal to noise ratio that needs is also different, and received signal to noise ratio and the decision of link attenuation send signal power, and it is also just different then to send signal power; Wherein, the measurements and calculations method of received signal to noise ratio can be example with the zero forcing equalization with reference to pertinent literature below, calculates to send signal power:

Suppose the bilateral power spectral density of white Gauss noise The channel condition information H (k) that receiving terminal obtains according to channel estimating, (k=0,1 ..., N-1), (the individual available subchannels of M≤N), establishing M the subchannel subscript of choosing is k to select M from big to small according to amplitude gain _i, (i=0,1 ..., M-1), the channel gain of these subchannels is | H (k _i) |, (i=0,1 ..., M-1), the noise gross power of the every frame in then balanced back is:

${\mathrm{\&sigma;}}^2=E\left(\underset{i=0}{\overset{M}{\mathrm{\&Sigma;}}}{\left|\frac{N\left(k_i\right)}{H\left(k_i\right)}\right|}^2\right)=\frac{N_0}{2}\underset{i=0}{\overset{M-1}{\mathrm{\&Sigma;}}}{\left|\frac{1}{H\left(k_i\right)}\right|}^2\left(W\right)$

Known required balanced back signal to noise ratio is SNR _Eq, the required received signal power of then every frame is:

$P_R={\mathrm{\&sigma;}}^2\&CenterDot;{\mathrm{SNR}}_{\mathrm{eq}}=\frac{N_0}{2}\&CenterDot;{\mathrm{SNR}}_{\mathrm{eq}}\underset{i=0}{\overset{M-1}{\mathrm{\&Sigma;}}}{\left|\frac{1}{H\left(k_i\right)}\right|}^2\left(W\right)$

Consider the link attenuation, establishing the link attenuation is L, and then required transmission signal power is:

$P_T=\frac{P_R}{L}=\frac{N_0}{2}\&CenterDot;\frac{1}{L}\&CenterDot;{\mathrm{SNR}}_{\mathrm{eq}}\underset{i=0}{\overset{M-1}{\mathrm{\&Sigma;}}}{\left|\frac{1}{H\left(k_i\right)}\right|}^2\left(W\right)$

By feedback channel this performance number is formed power control information and pass to transmitting terminal.

4. the Poewr control method in the selecting frequency single carrier wave blocking transmission system according to claim 1, it is characterized in that: transmitting terminal is according to the power control information that receives in the described step (3), make to send the required transmission power value that gross power equals to feed back, send signal.

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