CN105450259B - Intelligent meter data recording system multi-carrier communication module self-adaptive modulation method - Google Patents
Intelligent meter data recording system multi-carrier communication module self-adaptive modulation method Download PDFInfo
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- CN105450259B CN105450259B CN201510781265.4A CN201510781265A CN105450259B CN 105450259 B CN105450259 B CN 105450259B CN 201510781265 A CN201510781265 A CN 201510781265A CN 105450259 B CN105450259 B CN 105450259B
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- 238000004891 communication Methods 0.000 title claims abstract description 21
- 238000000034 method Methods 0.000 title claims abstract description 15
- 230000005540 biological transmission Effects 0.000 claims abstract description 16
- 230000003044 adaptive effect Effects 0.000 claims abstract description 11
- 239000000969 carrier Substances 0.000 claims description 6
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- 238000006243 chemical reaction Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B3/00—Line transmission systems
- H04B3/54—Systems for transmission via power distribution lines
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- G—PHYSICS
- G08—SIGNALLING
- G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
- G08C19/00—Electric signal transmission systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2626—Arrangements specific to the transmitter only
- H04L27/2627—Modulators
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2626—Arrangements specific to the transmitter only
- H04L27/2646—Arrangements specific to the transmitter only using feedback from receiver for adjusting OFDM transmission parameters, e.g. transmission timing or guard interval length
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
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Abstract
The invention discloses a kind of intelligent meter data recording system multi-carrier communication module self-adaptive modulation methods.This method is under the limitation of target error rate and fix power allocation, sub-carrier signal-noise ratio estimated value and multi-subcarrier signal-to-noise ratio (SNR) estimation value are obtained by the estimation of multi-carrier communication module channel gain and frame preamble data first, then the additional bit of OFDM symbol can be increased to according to signal-to-noise ratio (SNR) estimation acquisition, adaptive the distributing to of additional bit finally influences into average error rate minimum subcarrier by the increment bit error rate of subcarrier, so as to obtain the modulator approach close to optimum transmission rate, reduce the complexity of operation and be easily achieved and apply.
Description
Technical Field
The invention relates to an adaptive modulation method for an OFDM (Orthogonal frequency division Multiplexing) communication module of an intelligent meter reading system.
Background
The existing intelligent meter reading system multi-carrier communication module has the standard of G3 standard OFDM power line carrier communication technology and PRIME standard OFDM power line carrier communication technology, the PRIME standard is similar to the G3 standard, so the G3 standard is taken as an example to illustrate the defects of the prior art. The G3 standard switches each subcarrier between different modes on the basis of meeting the requirement of transmission rate or bit error rate, but each subcarrier uses the same modulation mode and transmission power, uses to close some subcarriers with serious interference to prevent interference, designs parameters such as modulation and coding according to the worst channel condition, the system includes many overheads for overcoming the worst condition, so do it to trade the cost of spectrum utilization rate and information transmission rate for reliability, the main disadvantage is as follows:
1. the robustness of the sub-carrier with larger noise interference will be weakened, so the transmission error is serious and the transmission efficiency is low.
2. For subcarriers with high signal-to-noise ratio, bandwidth is wasted by adopting a modulation mode with low transmission efficiency.
3. All subcarriers adopt the same modulation and demodulation mode, which will reduce the transmission efficiency and anti-interference capability of the whole system.
Disclosure of Invention
The invention aims to provide a non-iterative adaptive modulation method of an optimal transmission Rate for a multi-carrier communication module of an intelligent meter reading system on the premise of a given target Bit Error Rate (BER) and fixed power distribution.
The invention provides a multi-carrier communication module self-adaptive modulation method of an intelligent meter reading system, which comprises the following steps:
step 1, initializing a target bit error rate PT，PTAll sub-carriers are allocated with fixed power according to the requirement of the transmission performance of the multi-carrier communication module;
step 2, calculating the Signal-to-Noise Ratio (SNR) gamma of the subcarriern；
Step 3, the signal-to-noise ratio gamma of the sub-carrier wavenAt Pn＜PTUnder the restriction of (2), the number b of bits that can be pre-allocated is calculated for each subcarriernWherein b isnAnd PnRespectively, the bit and BER of each subcarrier, and calculating the average bit error rate
Step 4, the signal-to-noise ratio gamma of the sub-carrier wavenAnd average bit error rateCalculating the current multi-channel signal-to-noise ratio gammamcAnd average number of bits of subcarrier
Step 5, in PTUnder the limitation of (2), by γmcCalculating the maximum average number of bits per subcarrierAnd additional bits I that can be added to the OFDM symbol;
step 6, when the subcarrierCalculating the incremental bit error rate delta P on the sub-carriernI.e. calculating the increased error rate when the subcarrier is allocated with the maximum bit number, and calculating the delta PnIn ascending order of value;
step 7, add I extra bits to the lowest Δ PnThe sub-carriers of (a).
The invention has the beneficial effects that: under the limit of target error rate and fixed power distribution, the invention determines extra bits which can be distributed to subcarriers according to the signal-to-noise ratio estimated value of each subcarrier and the signal-to-noise ratio estimated value of multiple subcarriers, and distributes the extra bits to the subcarriers with the minimum influence on the average error rate, thereby adaptively adjusting the bit number of each subcarrier, obtaining a modulation method which is close to the optimal transmission rate, reducing the complexity of operation and being easy to realize and apply.
Drawings
Fig. 1 is a system structure diagram of a multi-carrier communication module of the intelligent meter reading system.
Fig. 2 is a multi-carrier communication module packet frame structure of the intelligent meter reading system.
Fig. 3 is a flow chart of the method of adaptive modulation of the present invention.
Detailed Description
The intelligent meter reading system power carrier module is directly oriented to a physical media power line which actually undertakes data transmission, and provides a physical connection for transmitting an original bit stream for upper-layer application data on the power line, so that the power carrier module directly faces various interferences and attenuations of the power line.
The invention will be further explained with reference to the drawings.
As shown in fig. 1, the sending end of the multi-carrier communication module of the intelligent meter reading system includes a forward error control encoder and an OFDM modulation module. The data to be transmitted is firstly subjected to crosstalk, RS coding, convolutional coding and interleaving processing, then adaptive modulation is carried out and IFFT conversion is carried out. The structure of the corresponding receiving end is just opposite to that of the transmitting end, the received data is firstly subjected to symbol synchronization, then FFT (fast Fourier transform) conversion is carried out, and meanwhile, the channel is estimated. And demodulating the data after FFT conversion to change the multi-system data bit into a 2-system data code stream, then performing de-interleaving, Viterbi decoding and de-crosstalk processing to finally obtain the data of the transmission end.
The frequency attenuation characteristic of the low-voltage power line determines that different subcarriers have different noise interferences, and on the premise that the bandwidth and the transmission power are fixed, in order to improve the transmission capacity of the OFDM system, an adaptive modulation mode is adopted in an OFDM carrier module, and bits are dynamically allocated according to the SNR estimation of a carrier channel.
As shown in fig. 2, the multi-carrier communication module packet frame structure of the intelligent meter reading system of the present invention includes a preamble, a frame control header and a data segment. The preamble sequence is composed of 8 identical symbols and 1.5 symbols inverted to the identical symbols, the SNR of the subcarrier is obtained by using the identical 8 symbols and the receiver channel gain estimation, and the subcarrier signal-to-noise ratio is calculated according to the following formula:
n1, 2, N, where ρn，HnAndrespectively, the signal power, channel gain estimate and noise power of the nth subcarrier, and N is the number of subcarriers used. Since the preamble sequence is known, the subcarrier signal power ρnKnowing the channel gain HnObtained from channel estimation, noise powerThe power and rho of the preamble sequence at the receiving endn×|Hn|2And subtracting to obtain the result.
The frame control header contains important information for demodulating the data frame. The frame control header is followed by data symbols, called payload.
The following describes, with reference to fig. 3, the adaptive modulation method for a multi-carrier communication module of an intelligent meter reading system, which is provided by the present invention, and the method includes the following specific implementation steps:
step 1, initializing a target bit error rate PTAll subcarriers are allocated with fixed power;
step 2, using the preamble data of the previous frame and the channel gain estimated value HnCalculating subcarrier signal-to-noise Ratio (SNR, SignalNoise Ratio):
n1, 2, N, where ρn，HnAndthe signal power, the channel gain estimation value and the noise power of the nth subcarrier are respectively, and N is the number of used subcarriers;
step 3, using sub-carrier signalNoise ratio gammanAt Pn＜PTUnder the restriction of (2), the number b of bits that can be pre-allocated is calculated for each subcarriernSum subcarrier mean error rate
Wherein, bnAnd PnBit and BER for each subcarrier, respectively;
step 4, the signal-to-noise ratio gamma of the sub-carrier wavenAnd average bit error rateCalculating the current multi-channel signal-to-noise ratio gammamcAnd average number of bits of subcarrier
Wherein,andrespectively, the average number of bits of the subcarrier and the average BER, gammamcIs the multi-channel signal-to-noise ratio;
step 5, in PTUnder the limitation of (2), by γmcCalculating the maximum average number of bits per subcarrier
Step 6, calculating the extra bits that can be added to the OFDM symbol:
step 7, when the subcarrierCalculating the incremental bit error rate delta P on the sub-carriernThat is, when calculating the maximum bit number allocated to the subcarrier, the increased error rate:
n is 1,2, whereinIs the bit error rate when the nth sub-carrier adopts maximum bit modulation, and is divided into delta PnIn ascending order of value.
Step 8, add I extra bits to the lowest Δ PnThe sub-carriers of (a). By applying a minimum Δ P to eachnDistributing maximum bit number to subcarrier, i.e. adopting maximum order modulation allowed by system, until all I extra bits are distributed or lowest delta PnThe subcarriers are allocated the maximum number of bits.
Claims (3)
1. A multi-carrier communication module self-adaptive modulation method of an intelligent meter reading system calculates extra bits which can be added to a current symbol sub-carrier through a matched formula, and finds out the sub-carrier which has the minimum influence on the average bit error rate in all sub-carriers to distribute, and is characterized in that: the adaptive modulation method of the multi-carrier communication module of the intelligent meter reading system comprises the following steps:
step 1, initializing a target bit error rate PT，PTAll sub-carriers are allocated with fixed power according to the requirement of the transmission performance of the multi-carrier communication module;
step 2, calculating the Signal-to-Noise Ratio (SNR) gamma of the subcarriern；
Step 3, the signal-to-noise ratio gamma of the sub-carrier wavenAt Pn<PTUnder the limitation of (2), calculating the maximum pre-allocatable bit number b for each subcarriernWherein b isnAnd PnRespectively, the Bit Error Rate (BER) of each subcarrier, and calculating the average Bit Error Rate (BER)
Step 4, the signal-to-noise ratio gamma of the sub-carrier wavenAnd average bit error rateCalculating the current multi-channel signal-to-noise ratio gammamcAnd average number of bits of subcarrier
Step 5, in PTUnder the limitation of (2), by γmcCalculating the maximum average number of bits per subcarrierAnd additional bits I that can be added to the OFDM symbol;
step 6, when the subcarrierCalculating the incremental bit error rate delta P on the sub-carriernI.e. calculating the increased error rate when the subcarrier is allocated with the maximum bit number, and calculating the delta PnIn ascending order of value;
step 7, add I extra bits to the lowest Δ PnThe sub-carriers of (a).
2. The adaptive modulation method for the multi-carrier communication module of the intelligent meter reading system according to claim 1, wherein the calculation of the sub-carrier signal-to-noise ratio is performed by using pilot data and a channel estimation value at a receiving end.
3. The adaptive modulation method for the multi-carrier communication module of the intelligent meter reading system according to claim 1, wherein the I extra bits are added to the lowest delta PnFor each lowest Δ P, the subcarriernDistributing maximum bit number to subcarrier, i.e. adopting maximum order modulation allowed by system, until all I extra bits are distributed or lowest delta PnThe subcarriers are allocated the maximum bits.
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| CN106506047B (en) | 2016-12-20 | 2019-05-14 | 创达特（苏州）科技有限责任公司 | A kind of carrier communication method of low-voltage power line, apparatus and system |
| CN110708091A (en) * | 2019-06-27 | 2020-01-17 | 湖南华青智能科技有限公司 | Network communication system, method and device based on power line |
| CN112763003A (en) * | 2020-10-14 | 2021-05-07 | 陕西阳光时代电气有限公司 | Data acquisition system and method based on intelligent instrument communication unit in power grid |
| CN112910699A (en) * | 2021-01-28 | 2021-06-04 | 山东山大世纪科技有限公司 | Intelligent fault detection method and device for power internet of things |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1921469A (en) * | 2006-09-14 | 2007-02-28 | 北京邮电大学 | Non-equivalent code error rate self-adaptive transmitting method for OFDM system |
| CN101483502A (en) * | 2009-02-24 | 2009-07-15 | 北京邮电大学 | Adaptive transmission method suitable for hybrid modulation mode |
| CN104283830A (en) * | 2013-07-01 | 2015-01-14 | 北京信威通信技术股份有限公司 | Self-adaptive modulating method |
| WO2015131812A1 (en) * | 2014-03-07 | 2015-09-11 | 富士通株式会社 | Signal transmission device and multicarrier communication system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1921469A (en) * | 2006-09-14 | 2007-02-28 | 北京邮电大学 | Non-equivalent code error rate self-adaptive transmitting method for OFDM system |
| CN101483502A (en) * | 2009-02-24 | 2009-07-15 | 北京邮电大学 | Adaptive transmission method suitable for hybrid modulation mode |
| CN104283830A (en) * | 2013-07-01 | 2015-01-14 | 北京信威通信技术股份有限公司 | Self-adaptive modulating method |
| WO2015131812A1 (en) * | 2014-03-07 | 2015-09-11 | 富士通株式会社 | Signal transmission device and multicarrier communication system |
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