CN115426009A - LTE modulation and demodulation method and device for frequency spectrograph - Google Patents
LTE modulation and demodulation method and device for frequency spectrograph Download PDFInfo
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- CN115426009A CN115426009A CN202210912829.3A CN202210912829A CN115426009A CN 115426009 A CN115426009 A CN 115426009A CN 202210912829 A CN202210912829 A CN 202210912829A CN 115426009 A CN115426009 A CN 115426009A
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- 238000012545 processing Methods 0.000 claims abstract description 3
- 238000001228 spectrum Methods 0.000 claims description 12
- 238000010586 diagram Methods 0.000 claims description 6
- 230000002159 abnormal effect Effects 0.000 claims description 4
- 230000005540 biological transmission Effects 0.000 claims description 3
- 230000009466 transformation Effects 0.000 claims 1
- 238000012360 testing method Methods 0.000 abstract description 6
- 238000005259 measurement Methods 0.000 abstract description 4
- 238000004891 communication Methods 0.000 abstract description 2
- 238000005516 engineering process Methods 0.000 description 3
- 238000010295 mobile communication Methods 0.000 description 3
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
- H04B1/12—Neutralising, balancing, or compensation arrangements
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/30—Monitoring; Testing of propagation channels
- H04B17/309—Measuring or estimating channel quality parameters
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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
- H04L27/2627—Modulators
- H04L27/2628—Inverse Fourier transform modulators, e.g. inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] 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
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2649—Demodulators
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Abstract
The invention belongs to the technical field of communication, and provides a frequency spectrograph LTE modulation and demodulation method, which comprises the following steps: firstly, modulating and demodulating a frequency spectrograph LTE, and acquiring system synchronization information after analyzing a PSS/SSS channel; secondly, carrying out channel estimation by the LTE modulation and demodulation of the frequency spectrograph according to the port; step three, the port identification module completes signal port identification as a basis for equalization processing; and step four, the equalizer further performs noise suppression according to the port activation state, and further optimizes the signal. The invention also provides a frequency spectrograph LTE modulation and demodulation device. Under the scene of effectively identifying the channel port, the channel equalization realization process is optimized, and the accuracy and precision of the measurement test are improved.
Description
Technical Field
The invention belongs to the technical field of communication, and particularly relates to a frequency spectrograph LTE modulation and demodulation method and device.
Background
With the development of modern mobile communication technology, the combination of a frequency spectrograph and a public mobile communication network is tighter and tighter, the modem plug-in corresponding to 3G/4G/5G is more and more perfect, and the modem technology has become another soul of the frequency spectrograph. A major branch of spectrum analyzers, hand-held spectrum analyzers, is also playing an increasingly important role in the deployment and maintenance of mobile communication networks. Different from general terminal equipment, modulation and demodulation in a handheld frequency spectrograph needs to meet more and more test and experiment requirements of users. For example, in the LTE system modem, how to quickly and effectively obtain the port information of the signal and effectively utilize the port information to quickly and effectively evaluate the signal quality is a key to analyze the MIMO technology of the LTE system.
According to the 3gpp protocol, the port information is implicit in the physical broadcast channel, and only the sending port information can be obtained according to the terminal implementation manner, which has three results: the single port (port 0), the two ports (port 0, port 1) and the four ports (port 0, port1, port2, port 3), the port identification mode can not meet the test requirement, and only one port usually works in the test; or channel equalization is performed according to the 4 ports, in the scheme, noise is removed from other ports of the effective port, and noise of other ports is introduced by adopting the 4-port equalization, so that some test measurement errors are caused.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a method and a device for modulating and demodulating a frequency spectrograph LTE (long term evolution), which are used for optimizing a channel equalization implementation process and improving the accuracy and precision of measurement and test under the scene of effectively identifying a channel port.
In order to solve the technical problems, the invention provides two technical solutions,
in a first aspect, a spectrum analyzer LTE modulation and demodulation method includes: firstly, a frequency spectrograph LTE modulates and demodulates, and obtains system synchronization information after analyzing a PSS/SSS channel; secondly, carrying out channel estimation by the LTE modulation and demodulation of the frequency spectrograph according to the port; step three, the port identification module completes signal port identification as a basis for equalization processing; and step four, the equalizer further performs noise suppression according to the port activation state, and further optimizes the signal.
And further, adding a step five, and deducting abnormal constellation point information introduced by an inactivated port from a demodulation constellation diagram by combining the actual MIMO transmission process.
Further, the spectrum analyzer LTE modulates and demodulates the pilot information according to the port0 to the port3 as a local signal.
Further, the channel estimation result of each port is subjected to IDFT conversion, and is converted into a time domain signal from a frequency domain, so that the time domain channel estimation result of each port is obtained.
Further, the power value of the time domain channel estimation result of each port is calculated, and the maximum value is found.
Further, there are 4 ports, and the channel estimation finds the maximum power value from the 4 port-related powers.
In a second aspect, an LTE modem apparatus for a spectrum analyzer includes a signal receiver, a channel estimation apparatus, a domain signal converter, and a port identification module, where the port identification module is configured to calculate a time domain correlation power and search for a maximum correlation peak; and entering the port identification process to obtain activated port information.
Further, the device also comprises an equalizer, wherein the equalizer is used for further carrying out noise suppression and further optimizing the signal.
Has the advantages that:
the invention can effectively analyze the port combination, provides basis for subsequent detection, selects the optimal equalizer according to the port activation state, further inhibits the system noise by the equalizer, reduces the influence of the equalizer on the measurement, improves the detection reliability, and can eliminate abnormal constellation points by combining an MIMO mode and improve the user interface perception.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
fig. 1 is a block diagram of a spectrometer LTE demodulation implementation;
fig. 2 is a diagram of a spectrum analyzer LTE demodulation apparatus;
FIG. 3 is a flow chart of port identification;
fig. 4 is a diagram of equalizer optimization.
Detailed Description
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it should be understood that they are presented herein only to illustrate and explain the present invention and not to limit the present invention.
The embodiment is as follows:
1) The method comprises the following steps that 1) in an LTE (Long term evolution) system, PSS/SSS (Power System synchronization/second-frequency signal) channels are analyzed to obtain system synchronization information;
2) The method comprises the steps that channel estimation is carried out on a frequency spectrograph LTE modulation and demodulation according to 4 ports, namely, channel estimation is carried out on a received signal according to pilot frequency information from port0 to port3, and the received signal is recorded as cstPort0Freqz, cstPort1Freqz, cstPort2Freqz and cstPort3Freqz, and a reference for generation of a port pilot frequency signal is a 3gpp.211 protocol; an LS (least square method) and MMSE (minimum mean square error) channel estimation scheme is adopted;
3) After the frequency domain channel estimation result is compensated with 0, the channel estimation result is a power of 2, IFFT fast operation transform is used to convert the frequency domain into a Time domain signal, cstPort0Time = IFFT ([ cstPort0Freqz 0 ]), other ports are similarly calculated, and the Time domain channel estimation result of each port can be obtained and recorded as: cstPort0Time, cstPort1Time, cstPort2Time, cstPort3Time, 0 in the above formula representing 0 vector; in different signal bandwidths, the lengths of 0 vectors are not consistent, and the 0 vectors with 112 lengths in the 20M bandwidth can be selected to form 512-point IFFT. The following description will be given by taking lte 20M bandwidth as an example.
4) Calculating power values of 512 complex numbers of time domain channel estimation of each port, and finding a maximum value, wherein the calculation formula is as follows: maxcstPort0TimeCorrPower = max (abs (cstPort 0 Time)); the other ports are calculated similarly and are respectively MaxcstPort0TimeCorrPower, maxcstPort1TimeCorrPower, maxcstPort2TimeCorrPower and MaxcstPort3TimeCorrPower; the maximum value of the relevant power indicates the relevant power value of the pilot frequency and the local pilot frequency of each port, and the greater the relevant power value, the pilot frequency information of the port is probably contained in the received signal;
5) Finding the maximum power value from the 4 port-related powers, which is recorded as:
MaxPowerCorr＝max{MaxcstPort(0\1\2\3)TimeCorrPower}；
6) When MaxPowerCorr = MaxcstPort0TimeCorrPower, it indicates that port0 is valid; setting validity judgment thresholds (A x MaxPowerCorr) of other ports at the moment, and if the other ports meet the condition, indicating that the other ports are valid activated ports; if the threshold setting is not met, the port is considered inactive. Only the port0 is activated, the system only supports a single port, and the system performs channel estimation and equalization according to the single port; the port1 is also activated, the port 2/the port3 is not activated, the system supports the port 0/the port1 at the moment, and channel estimation and equalization are carried out according to the 2 ports; if one of the ports 2/3 is active, it indicates that the system supports 4 ports (i.e. the ports that are not active at this time are also considered to be active, i.e. the system does not separately activate ports 0 and 3), otherwise it supports 2 ports.
7) When MaxPowerCorr = MaxcstPort1TimeCorrPower indicates that port1 is activated, a threshold is determined according to port validity (a × MaxPowerCorr), if port0 is not activated, the system is considered to support port1 at this time, and other ports are not activated; if the port0 is activated, one of the port 2/port 3 is activated, the system supports 4 ports, otherwise, the system supports 2 ports;
8) When MaxPowerCorr = MaxcstPort2TimeCorrPower indicates that port2 is activated, a threshold is determined according to port validity (a × MaxPowerCorr), if port0 is not activated, the system is considered to support only port2 at this time, and other ports are not activated; if Port0 is activated, the system is considered to support 4 ports;
9) According to the rule of 6) 7) 8), for the ports which are not activated, the channel estimation result of the ports is directly set to be 0 in the receiver equalization process, and the influence of the inactive ports on link quality analysis is reduced.
10 If only port0 is active, the equalizer selects a single-port equalization process; if port 0/port 1 is active, the equalizer selects 2 ports for equalization; if port 0/1/2/3 is active, 4 ports are used for balancing; if only the port1 is activated, 2 ports are selected for equalization, and the channel estimation result of the port0 is set to be 0; only port 2/port 3 is activated, 4 ports are selected for equalization, and the channel estimation results of other ports are set to be 0.
11 In conjunction with the actual MIMO transmission process, the abnormal constellation point information introduced due to the inactive port is subtracted from the demodulation constellation diagram. For example, for 4 ports SFBC (transmit diversity technique), assuming port0 or port1 is active, the constellation points output by port 2/port 3 can be eliminated; assuming that only port2 or port3 is active, the constellation points output by port 0/port 1 can be culled.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A frequency spectrograph LTE modulation-demodulation method is characterized by comprising the following steps:
firstly, modulating and demodulating a frequency spectrograph LTE, and acquiring system synchronization information after analyzing a PSS/SSS channel;
secondly, carrying out channel estimation by the LTE modulation and demodulation of the frequency spectrograph according to the port;
step three, the port identification module completes signal port identification as a basis for equalization processing;
and step four, the equalizer further performs noise suppression according to the port activation state, and further optimizes the signal.
2. The spectrum analyzer LTE modulation-demodulation method of claim 1, characterized in that: and adding a step five, and deducting abnormal constellation point information introduced by the inactivated port from the demodulation constellation diagram by combining the actual MIMO transmission process.
3. The method of claim 1 for spectrum analyzer LTE modulation and demodulation, characterized in that: and the frequency spectrograph LTE modulation and demodulation takes the pilot frequency information from the port0 to the port3 as a local signal.
4. The spectrum analyzer LTE modulation-demodulation method of claim 3, characterized in that: and performing IDFT transformation on the channel estimation result of each port, and converting the channel estimation result from the frequency domain into a time domain signal to obtain the time domain channel estimation result of each port.
5. The spectrum analyzer LTE modulation-demodulation method of claim 4, characterized in that: and calculating the power value of the time domain channel estimation result of each port and finding the maximum value.
6. The spectrum analyzer LTE modulation-demodulation method according to any one of claims 3-5, characterized in that: there are 4 ports and the channel estimation finds the maximum power value from the 4 port-related powers.
7. An apparatus of a spectrum analyzer LTE modem, comprising a signal receiver, a channel estimation apparatus, and a domain signal converter, characterized in that: the device also comprises a port identification module, wherein the port identification module is used for calculating the time domain correlation power and searching the maximum correlation peak value; and entering the port identification process to obtain activated port information.
8. The apparatus of a spectrometer LTE modem of claim 7, wherein: the device also comprises an equalizer, wherein the equalizer is used for further carrying out noise suppression and further optimizing the signal.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102315904A (en) * | 2011-09-05 | 2012-01-11 | 新邮通信设备有限公司 | Method for optimizing physical uplink control channel detection and measurement |
| CN110011744A (en) * | 2018-12-26 | 2019-07-12 | 一诺仪器（中国）有限公司 | Port detecting method, system and terminal |
| US20190235600A1 (en) * | 2016-10-24 | 2019-08-01 | Fujitsu Technology Solutions Intellectual Property Gmbh | Computer system having at least one interface and method of restricting power output |
| CN111555991A (en) * | 2020-05-06 | 2020-08-18 | Oppo广东移动通信有限公司 | Receiving device, terminal, equalization processing method, device and storage medium |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102315904A (en) * | 2011-09-05 | 2012-01-11 | 新邮通信设备有限公司 | Method for optimizing physical uplink control channel detection and measurement |
| US20190235600A1 (en) * | 2016-10-24 | 2019-08-01 | Fujitsu Technology Solutions Intellectual Property Gmbh | Computer system having at least one interface and method of restricting power output |
| CN110011744A (en) * | 2018-12-26 | 2019-07-12 | 一诺仪器（中国）有限公司 | Port detecting method, system and terminal |
| CN111555991A (en) * | 2020-05-06 | 2020-08-18 | Oppo广东移动通信有限公司 | Receiving device, terminal, equalization processing method, device and storage medium |
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Application publication date: 20221202 |