CN113556150A - Frame detection method for power line carrier communication - Google Patents
Frame detection method for power line carrier communication Download PDFInfo
- Publication number
- CN113556150A CN113556150A CN202110576386.0A CN202110576386A CN113556150A CN 113556150 A CN113556150 A CN 113556150A CN 202110576386 A CN202110576386 A CN 202110576386A CN 113556150 A CN113556150 A CN 113556150A
- Authority
- CN
- China
- Prior art keywords
- frame detection
- data
- cross
- power line
- line carrier
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B3/00—Line transmission systems
- H04B3/02—Details
- H04B3/32—Reducing cross-talk, e.g. by compensating
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B3/00—Line transmission systems
- H04B3/54—Systems for transmission via power distribution lines
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Power Engineering (AREA)
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
Abstract
The invention discloses a frame detection method for power line carrier communication. The frame detection method relates to power line carrier communication, and comprises digital down-sampling processing, digital frequency shift, filter noise filtering, data truncation processing, energy calculation, cross-correlation calculation of a received signal and a local sequence, and frame detection processing.
Description
Technical Field
The invention relates to power line carrier system communication, in particular to implementation of a power line carrier communication frame detection method.
Background
In recent years, with the development of the communication industry, the power line network can be used as both a power line and a network cable because of the wide coverage area. Therefore, the power line network has a potential to become the best transmission mode in wired transmission communication, but effective transmission of information must be ensured. For power line carrier communication, the reliability of the system is particularly important, and if the reliability is low, the performance of the communication system is reduced, and data transmission is affected. The power line communication technology has many difficulties, such as strong signal attenuation, accompanied by multipath time delay, and more loads on the power line, and can be switched in at any time, any place and any place, so that interference of various noises is formed, and the complexity of the noises can cause serious interference to communication signals. Therefore, the robustness of the frame detection method, which is a key point in power line carrier communication, is of great significance for improving communication quality and constructing a robust communication system. The frame detection is used as a first door of the identification signal, and the high-reliability frame detection method can ensure low false detection rate and low omission factor in the environment with low signal-to-noise ratio. Therefore, a low complexity and high reliability frame detection method has been one of the main directions of signal detection research.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: in order to make up for the above-mentioned deficiencies of the prior art, a frame detection method for power line carrier communication is proposed. The method is low in calculation complexity, high in reliability and suitable for power line carrier communication in severe environments.
The technical problem of the invention is solved by the following technical scheme: the invention provides a frame detection method for power line carrier communication, which comprises the following steps:
and 6, carrying out frame detection judgment processing by using the calculated energy and the cross-correlation result.
Compared with the prior art, the invention has the advantages that:
1. through the matching of frequency shift and a filter, the influence of out-of-band noise is reduced, and the result is more stable and reliable by using the virtual real part to perform cross-correlation calculation than by using the real part only;
2. by carrying out truncation processing on the data, the complexity of cross-correlation calculation is reduced;
3. simplifying energy calculation, and only carrying out modulus summation processing on data to ensure that an energy result and a cross-correlation result keep the same order of magnitude;
4. the false detection rate caused by noise is reduced by multiplying the energy result by a coefficient to serve as a dynamic threshold;
5. and the corresponding positions of the symbol cross-correlation result and the previous symbol cross-correlation result are subjected to superposition average processing and modulus output, so that the influence of noise is reduced, the stability of a symbol peak value is ensured, and the robustness of frame detection is improved.
Drawings
The drawings are examples of the invention for further understanding and explanation and therefore should not be considered as limiting the invention. In the drawings:
fig. 1 is a process flow diagram of a frame detection method for power line carrier communication according to the present invention;
fig. 2 is a schematic diagram of cross-correlation calculation of the frame detection method for power line carrier communication according to the present invention;
fig. 3 is a cross-correlation result comparison diagram of the frame detection method for power line carrier communication according to the present invention;
FIG. 4 is a graph showing the comparison result of the frame detection success rate of the frame detection method for power line carrier communication according to the present invention;
fig. 5 is a comparison result diagram of the frame detection omission factor of the frame detection method for power line carrier communication according to the present invention.
Detailed Description
The invention will be described in further detail with reference to the following detailed description and accompanying drawings:
the present embodiment is a frame detection method for power line carrier communication, and the parameter settings are as shown in table 1 below:
TABLE 1
| Parameter(s) | Value taking |
| Frequency band | CENELEC-B in G3 PLC protocol |
| Signal to noise ratio | -8 to 6dB (data segment frequency domain signal-to-noise ratio) |
| Number of packets | 10000 (per SNR) |
In the frame detection method of the embodiment, the flow of frame detection is as shown in fig. 1, and the input data is firstly filtered and down-sampled; then, frequency shift processing is carried out on the down-sampled data, so that the effective data is shifted to zero intermediate frequency, and meanwhile, real data is changed into complex data; then filtering the data after frequency shift to filter out-of-band interference noise; and performing truncation processing on the filtered data to reduce the bit width of effective data. And respectively carrying out energy calculation and cross-correlation calculation by using the truncated data, and carrying out frame detection judgment by using the energy result and the cross-correlation result obtained by calculation to determine whether the received signal is a real frame signal.
In fig. 1, in the frame detection method of the embodiment, the frame detection process includes 6 steps:
step 1: the filter is a low pass filter and the down-sampled data rate is 0.4M.
Step 2: the frequency shift is accomplished by cyclically multiplying the data after down-sampling by [1, -j, -1, j ].
And step 3: the used filter is a low-pass filter, and the passband bandwidth is the bandwidth of the frequency point occupied by the signal.
And 4, step 4: the truncation process is carried out on the signal to reserve n bits, one sign bit and n-1 bit data which are more than 2n-1Data of-1 is reserved as 2n-1-1, less than-2n-1Is reserved as-2n-1Other data may be retained with full precision using n bits, where n is 6 in this embodiment.
And 5: this step involves energy calculation and cross-correlation calculation.
Energy calculation, in fact using amplitude instead of energy value, energy of each point is the module value of data, and the length of the sliding window of energy is calculated to be the length of one OFDM symbol.
And (4) performing cross-correlation calculation, wherein the local sequence is stored according to [ -1, 0, 1], and the lengths of the imaginary part and the real part of the local sequence are respectively the length of one OFDM symbol.
The cross-correlation calculation adopts a method that a real part and an imaginary part jointly participate in the cross-correlation calculation.
As shown in fig. 2, after the cross-correlation calculation of the imaginary real part is completed, the calculation result is overlapped with the result before the cross-correlation modulo of the previous symbol period, and then the result is averaged and then is used as the cross-correlation output result of the current symbol after the modulo processing is performed
Step 6: and carrying out frame detection judgment by using the energy calculation result and the cross-correlation calculation result.
In the step, the energy value is multiplied by a coefficient a (0< a <1, and the value of a is suggested to be 1/8-1/2) as a dynamic threshold for detecting the cross-correlation peak, wherein a is 1/4 in the embodiment.
In each symbol period, the cross-correlation peak is searched, and the peak in the symbol period is considered to be present if the maximum value in the symbol period is greater than the dynamic threshold.
The frame detection success is judged by the fact that peaks appear in three consecutive symbols and the peaks are periodic.
The peak periodicity is defined by the number of points between two peak intervals T- Δ T and T + Δ T, T being the number of points in one symbol period (in this embodiment, T is 256), and Δ T being a settable coefficient (in this embodiment, Δ T is 6).
In order to more intuitively explain the performance of the invention, firstly, cross-correlation calculation is carried out on the imaginary real part used in the embodiment, and compared with the traditional method for carrying out cross-correlation calculation only by using the real part; the frame detection method of the embodiment is then compared with the conventional frame detection method.
As shown in fig. 3, in the CENELEC-B frequency band (the number of available subcarriers is 16), a plurality of side peaks may appear in the conventional manner, and the peak value may fluctuate with the difference of the sampling point, while the peak value point is more stable and is not affected by the sampling start position as the result of performing the cross-correlation calculation using the imaginary real part in the present embodiment.
In order to verify the performance of the frame detection method of the embodiment, the method of the embodiment is compared with the conventional method, both the method and the conventional method use energy multiplied by a fixed coefficient as a dynamic threshold, three peaks are continuously detected as an identifier of successful frame detection, under the condition that almost no false detection is ensured, the positive detection rate and the negative detection rate are compared, and the comparison result is shown in fig. 4 and 5. As can be seen from the figure, by comparing the positive detection rate and the negative detection rate of the frame detection, the performance of the embodiment is improved significantly, and by simplifying the calculation, the calculation resources used by the embodiment are not much. Therefore, the embodiment is a more excellent frame detection scheme, and is suitable for complex power line environments.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several alternatives or obvious modifications can be made without departing from the spirit of the invention, and all equivalents in performance or use should be deemed to fall within the scope of the invention.
Claims (5)
1. A frame detection method for power line carrier communication, comprising the steps of:
step 1, carrying out down-sampling processing on a received signal to enable the signal rate to reach a required rate;
step 2, performing frequency shift processing on the down-sampled data, and shifting the frequency band of the data to zero intermediate frequency;
step 3, performing filter filtering processing on the data after frequency shift to filter out-of-band noise;
step 4, truncating the filtered data;
step 5, performing energy calculation on the truncated data and performing cross-correlation calculation on the truncated data and a local sequence;
and 6, carrying out frame detection judgment processing by using the calculated energy and the cross-correlation result.
2. A frame detection method for power line carrier communication according to claim 1, characterized in that:
in the step 4, the data is truncated: and completely reserving the data smaller than the threshold, and reserving the data exceeding the threshold according to the maximum value of the given bit width.
3. A frame detection method for power line carrier communication according to claim 1, characterized in that:
in the step 5, the energy calculation method includes: and carrying out modulus processing on the received data, taking a certain length as the length of a sliding window, and accumulating the data in the sliding window to obtain an energy value.
4. A frame detection method for power line carrier communication according to claim 1, characterized in that:
in the step 5, the cross-correlation calculation is a cross-correlation calculation of a virtual part and a real part, and the cross-correlation output result of the symbol is a cross-correlation result of a previous symbol (a result before modulus extraction) and a cross-correlation calculation result of the symbol and the local sequence, and the modulus output is obtained after the corresponding positions of the two are superposed and averaged.
5. A frame detection method for power line carrier communication according to claim 1, characterized in that:
in step 6, the frame detection and judgment method is as follows: and multiplying a coefficient by energy to serve as a dynamic threshold, wherein when the highest peak of the cross-correlation result of each symbol period is larger than the threshold and the periodicity of the highest peak meets the set requirement, the frame detection is successful, and otherwise, the frame detection is failed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110576386.0A CN113556150A (en) | 2021-05-26 | 2021-05-26 | Frame detection method for power line carrier communication |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110576386.0A CN113556150A (en) | 2021-05-26 | 2021-05-26 | Frame detection method for power line carrier communication |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113556150A true CN113556150A (en) | 2021-10-26 |
Family
ID=78101878
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110576386.0A Withdrawn CN113556150A (en) | 2021-05-26 | 2021-05-26 | Frame detection method for power line carrier communication |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113556150A (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040071200A1 (en) * | 2002-10-11 | 2004-04-15 | John Betz | System for direct acquisition of received signals |
| CN106571854A (en) * | 2016-11-05 | 2017-04-19 | 北京晓程科技股份有限公司 | Power carrier OFDM (orthogonal frequency division multiplexing) system frequency domain frame detection synchronization method and device |
| CN108040028A (en) * | 2017-12-22 | 2018-05-15 | 中国人民解放军国防科技大学 | OFDM system anti-interference signal detection and synchronization method based on local sequence cross-correlation detection |
| CN109769294A (en) * | 2017-11-09 | 2019-05-17 | 北京化工大学 | A kind of synchronous method based on FDD-LTE system |
| CN111107033A (en) * | 2019-12-20 | 2020-05-05 | 重庆邮电大学 | Downlink frame timing synchronization method for 5G system |
| CN111294089A (en) * | 2020-02-12 | 2020-06-16 | 西安电子科技大学 | Broadband power line carrier communication symbol synchronization method based on FPGA |
-
2021
- 2021-05-26 CN CN202110576386.0A patent/CN113556150A/en not_active Withdrawn
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040071200A1 (en) * | 2002-10-11 | 2004-04-15 | John Betz | System for direct acquisition of received signals |
| CN106571854A (en) * | 2016-11-05 | 2017-04-19 | 北京晓程科技股份有限公司 | Power carrier OFDM (orthogonal frequency division multiplexing) system frequency domain frame detection synchronization method and device |
| CN109769294A (en) * | 2017-11-09 | 2019-05-17 | 北京化工大学 | A kind of synchronous method based on FDD-LTE system |
| CN108040028A (en) * | 2017-12-22 | 2018-05-15 | 中国人民解放军国防科技大学 | OFDM system anti-interference signal detection and synchronization method based on local sequence cross-correlation detection |
| CN111107033A (en) * | 2019-12-20 | 2020-05-05 | 重庆邮电大学 | Downlink frame timing synchronization method for 5G system |
| CN111294089A (en) * | 2020-02-12 | 2020-06-16 | 西安电子科技大学 | Broadband power line carrier communication symbol synchronization method based on FPGA |
Non-Patent Citations (1)
| Title |
|---|
| 李年鑫: "低压电力线宽带载波通信系统设计及FPGA实现", 《中国优秀博硕士学位论文全文数据库(硕士)》 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3044899B2 (en) | Apparatus for coherent demodulation of digital data multiplexed in the time-frequency domain with evaluation and limit decision of the frequency response of the channel | |
| CN100527652C (en) | OFDM receiver and data demobulation method in OFDM receiver | |
| US20020172187A1 (en) | Method for data packet acquisition using split preamble | |
| EP1271823B1 (en) | Wireless communication transmitter and receiver | |
| EP0863644A2 (en) | An FFT-based multitone DPSK modem | |
| CA2143074C (en) | A .pi./4-dqpsk delay spread detection and compensation apparatus and method | |
| CN107070838B (en) | ROBO coding modulation and demodulation method based on G3-PLC frequency domain | |
| CN111756664A (en) | Short reference carrier index differential chaotic shift keying modulation and demodulation method and system | |
| US20120142302A1 (en) | Down sampling method and down sampling device | |
| CN103023529B (en) | Field programmable gate array (FPGA) based method for achieving synchronous detection of oversampling Golay sequence | |
| Zhao et al. | BER analysis of OFDM communication systems with intercarrier interference | |
| CN108123724B (en) | Communication system based on short wave narrow-band waveform | |
| JP2003517241A (en) | Multi-bit spread spectrum signaling | |
| US8743762B2 (en) | Partial DMM reception to reduce standby power | |
| CN1723648A (en) | Method for the time- and frequency-domain synchronisation of multiple devices in a transmission system with OFDM modulation | |
| CN113556150A (en) | Frame detection method for power line carrier communication | |
| CN1084979C (en) | Method and arrangement for separating signals operating in the same channel | |
| CN109286381B (en) | Automatic gain control circuit based on thermometer coding and control method | |
| CN1276632C (en) | Device and method for adjusting input gain for multiple signal formats in a data network | |
| CN114584179A (en) | Method for eliminating pulse interference in PLC time domain | |
| CN115150230A (en) | Orthogonal time-frequency space modulation system and method for improving spectrum efficiency | |
| JPH11154925A (en) | Digital transmitter | |
| CN111431833B (en) | Underwater current field communication method based on serial combination | |
| KR100542114B1 (en) | Wireless wireless communication system based on the orthogonal frequency division multiplexing and method for channel compensation | |
| AU756524B2 (en) | Demodulation and modulation circuit and demodulation and modulation method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WW01 | Invention patent application withdrawn after publication | ||
| WW01 | Invention patent application withdrawn after publication |
Application publication date: 20211026 |