CN104579426A - Low voltage power carrier transmission algorithm - Google Patents

Abstract

The invention discloses a lower voltage power carrier transmission algorithm. The low voltage power carrier transmission algorithm distributes bits according to power line carrier communication sub channels, and on the premise of keeping a target error bit rate, the spectrum efficiency of a system achieves the best; the algorithm firstly enables the performance of the system to achieve a best threshold, then, determines the modulation mode of each sub carrier, and finally, adjusts the power of the sub carriers.

Description

A kind of low-voltage power carrier launches algorithm

Technical field

The invention belongs to the communications field, particularly relate to a kind of low-voltage power carrier and launch algorithm.

Background technology

Because low-voltage powerline carrier communication number of users is many, multiple user can not share same subcarrier, large at intelligent distribution network low-pressure end number of users, the quantity that system sends subcarrier to user can increase, this certainly will increase communications burden, causes communication quality to decline, causes the wasting of resources.This and intelligent grid idea of development are disagreed.At power carrier transmitting terminal, the serial data exported from multiple user enters subcarrier and bit distribution module, different user data is assigned on different subcarriers by this module, therefore, multi-user's subcarrier and bit distribute just quite complicated, and traditional greedy algorithm is a kind of optimum allocation algorithm of single user.

Power line carrier signal emitter, needs to distribute signal, and in signal assigning process, channel estimating is a key factor, and conventional power-line carriers emitter mainly exists following shortcoming:

(1) signal multipath effect will cause interference;

(2) signal spectrum utilance and power system capacity on the low side.

Summary of the invention

The object of the embodiment of the present invention is to provide low-voltage power carrier to launch algorithm, is intended to solve conventional power-line carriers emitter and mainly there is signal multipath effect and will cause interference, signal spectrum utilance and power system capacity problem on the low side.

The present invention realizes like this, a kind of low-voltage power carrier to be launched algorithm and is carried out allocation bit according to the capacity of power line carrier communication subchannel, first make systematic function reach optimum thresholding, then determine the modulation system of each subcarrier, finally adjust the power of each subcarrier.

Further, described low-voltage power carrier is launched algorithm and is specifically comprised:

It is N that step one, supposing the system send sub-carrier number, calculate the SNR (i) of each subcarrier, (i=0,1, ... N), the bit number of each sub-carrier is b (i), and the sub-carrier number used is Nused, is ε (i) by sub-carrier signal energy normalized.As optimum thresholding γ max=0, iterations Niteration=0;

Step 2, Δ (i) for sub-carrier bit deviation, its expression formula are

Step 3, if n=N-1, the total bit number of actual transmission value is greater than 0; Calculate max threshold:

Wherein, B _targetthe total number of bits expecting to send, N _iteration=N _iteration+ 1;

If B _total~=B _target, and N _iteration< N _{max, iteration}, then N is made _used=N, then forwards step 2 to;

If B _total> B _target, calculate Δ _max(i), Δ (i)=Δ (i)+1, repeats this step until B _total=B _target;

If B _total< B _target, calculate Δ _min(i), Δ (i)=Δ (i)-1, repeats this step until B _total=B _targrt.；

Step 4, the transmitting power adjusted on each subcarrier, make, for each subcarrier bit b (i), have P _e(i)=P _{e, target};

Wherein, P _ei () is the bit error rate of i-th subcarrier, P _{e, target}for the target bit of system requirements;

Step 5, the same ratio factor is multiplied by all subcarriers used, makes total signal power ε _total=ε _target.

Low-voltage power carrier of the present invention to be launched algorithm and is carried out allocation bit according to the capacity of power line carrier communication subchannel, under the prerequisite safeguarding target bit, the spectrum efficiency of system is made to reach optimum, first algorithm makes systematic function reach optimum thresholding, then determine the modulation system of each subcarrier, finally adjust the power of each subcarrier.

Accompanying drawing explanation

Fig. 1 is the ofdm system schematic diagram that the embodiment of the present invention provides.

Embodiment

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with embodiment, this present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain this present invention, be not intended to limit the present invention.

Below in conjunction with drawings and the specific embodiments, application principle of the present invention is further described.

OFDM technology channel estimation method can be divided into following several, divides, can be divided into least-squares estimation (LS) and Minimum Mean Squared Error estimation (MMSE) according to the criterion estimated; According to whether inserting pilot tone, blind Channel Estimation and pilot-symbol aided channel estimation can be divided into; Channel estimation method that is blind or half-blindness utilizes the character property of transmission symbol or statistical property to carry out channel estimating.To the estimation of power line carrier communication channel, the normal method adopting insertion training sequence or pilot tone, by inserting certain known symbol in the data block sent, receiving terminal is estimated channel status by the size of known symbol and position, and ofdm system principle is as Fig. 1.

System subcarrier bit and power allocation can adopt constant power algorithm, chow algorithm and gradient allocation algorithm.According to low-voltage powerline carrier communication characteristic, in conjunction with the requirement of low-voltage network power carrier communication system to message transmission rate and communication quality, comparatively gradient allocation algorithm is poor for constant power algorithm overall performance, and although gradient allocation algorithm has good self-adjusted block performance, the secondary power that can realize transmitting needed for this bit is minimum, but algorithm complex is high, also higher to equipment requirement, inapplicable low-voltage powerline carrier communication.Chow algorithm distributes at channel gain, subcarrier bit and is all better than the above two in power division, therefore in this device, power carrier launches employing Chow algorithm.

The present invention realizes like this, a kind of low-voltage power carrier to be launched algorithm and is carried out allocation bit according to the capacity of power line carrier communication subchannel, first make systematic function reach optimum thresholding, then determine the modulation system of each subcarrier, finally adjust the power of each subcarrier.

Further, described low-voltage power carrier is launched algorithm and is specifically comprised:

It is N that S101, supposing the system send sub-carrier number, calculate the SNR (i) of each subcarrier, (i=0,1, ... N), the bit number of each sub-carrier is b (i), and the sub-carrier number used is Nused, is ε (i) by sub-carrier signal energy normalized.As optimum thresholding γ max=0, iterations Niteration=0.

S102, Δ (i) for sub-carrier bit deviation, its expression formula are

S103, if n=N-1, the total bit number of actual transmission b _totalvalue is greater than 0; Calculate max threshold:

Wherein, B _targetthe total number of bits expecting to send, N _iteration=N _iteration+ 1;

If B _total~=B _target, and N _iteration< N _{max, iteration}, then Nu is made _sed=N, then forwards step S102 to;

If B _total> B _target, calculate Δ _max, (i), Δ (i)=Δ (i)+1, repeats this step until B _total=B _targrt;

If B _total< B _target, calculate Δ _min(i), Δ (i)=Δ (i)-1, repeats this step until B _total=B _target.；

S104, the transmitting power adjusted on each subcarrier, make for each subcarrier bit b (i),

There is P _e(i)=P _{e, target};

Wherein, P _ei () is the bit error rate of i-th subcarrier, P _{e, target}for the target bit of system requirements;

S105, the same ratio factor is multiplied by all subcarriers used, makes total signal power ε _total=ε _target.

Low-voltage power carrier of the present invention to be launched algorithm and is carried out allocation bit according to the capacity of power line carrier communication subchannel, under the prerequisite safeguarding target bit, the spectrum efficiency of system is made to reach optimum, first algorithm makes systematic function reach optimum thresholding, then determine the modulation system of each subcarrier, finally adjust the power of each subcarrier.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (2)

1. a low-voltage power carrier launches algorithm, it is characterized in that, described low-voltage power carrier to be launched algorithm and is carried out allocation bit according to the capacity of power line carrier communication subchannel, first systematic function is made to reach optimum thresholding, then determine the modulation system of each subcarrier, finally adjust the power of each subcarrier.

2. low-voltage power carrier as claimed in claim 1 launches algorithm, it is characterized in that, described low-voltage power carrier is launched algorithm and specifically comprised:

It is N that step one, supposing the system send sub-carrier number, calculate the SNR (i) of each subcarrier, (i=0,1, ... N), the bit number of each sub-carrier is b (i), and the sub-carrier number used is Nused, is ε (i) by sub-carrier signal energy normalized.As optimum thresholding γ max=0, iterations Niteration=0;

Step 2, Δ (i) for sub-carrier bit deviation, its expression formula are

$\mathrm{\&Delta;}\left(i\right)=b\left(i\right)-\hat{b}\left(i\right)={\log }_8(1+\frac{\mathrm{SNR}\left(i\right)}{\mathrm{\&Gamma;}+{\mathrm{\&gamma;}}_{\max }\left(\mathrm{dB}\right)})-\hat{b}\left(i\right)$

Step 3, if n=N-1, the total bit number of actual transmission b _totalvalue is greater than 0; Calculate max threshold:

Wherein, B _targetthe total number of bits expecting to send, N _iteration=N _iteration+ 1;

If B _total ^~=B _target, and N _iteration< N _{max, iteration}, then N is made _used=N, then forwards step 2 to;

If B _total> B _target, calculate Δ _max(i), Δ (i)=Δ (i)+1, repeats this step until B _total=B _target;

If B _total< B _target, calculate Δ _min(i), Δ (i)=Δ (i)-1, repeats this step until B _total=B _target.；

Step 4, the transmitting power adjusted on each subcarrier, make for each subcarrier bit b (i),

There is P _e(i)=P _{e, target};

Wherein, P _ei () is the bit error rate of i-th subcarrier, P _{e, target}for the target bit of system requirements;

Step 5, the same ratio factor is multiplied by all subcarriers used, makes total signal power ε _total=ε _target.