CN102739328A - Error vector magnitude measurement device and method for satellite mobile communication terminal - Google Patents

Abstract

The invention discloses an error vector magnitude measurement device and a method for a satellite mobile communication terminal. The device comprises an input module, an output module, a control module, an EVM (Error Vector Magnitude) calculation module, a satellite mobile communication protocol simulation terminal module, a satellite mobile communication protocol simulation base station module, a duplexing module, a radio frequency processing module and an interface module. Through the simulation of a mobile communication channel and the calculation of error vector magnitude simulator to the actual communication process, the requirement on the testing of a satellite mobile communication system is met, and further, the vector magnitude device and the method are applicable to a GMR (Giant Magneto Resistance) system and very significant for actual engineering application.

Description

A kind of satellite mobile communication terminal vector amplitude error measurement mechanism and method

Technical field

The present invention relates to a kind of satellite mobile communication terminal vector amplitude error measurement mechanism and method, be used for the vector amplitude error of satellite mobile communication system measuring terminals signal.

Background technology

Be similar to existing general 2G communication gsm mobile communication system, GMR (GEO-Mobile Radio, geostationary orbit mobile communication) system is applied to mobile communication equally.The difference of GMR system and gsm system is that the latter is applied to land mobile communication, and all base station terminals and core net facility all are positioned at ground, and the former is applied to satellite mobile communication, and signal demand is Channel Transmission via satellite.

In the GMR system, different channels adopts different modulation modes, for main Traffic Channel (TCH3/6/9) and BCCH (BCCH), and general control channel (CCCH), the GMR system adopts π/4-CQPSK modulation system; With path channels (FACCH3) and DCCH (SDCCH), the GMR system adopts π/4-CBPSK modulation system for soon; For the DKAB signal, adopt π/4-DBPSK modulation system; Then adopt the 6PSK modulation for BACH (basic alarm channel) channel.These modulation systems are phase modulation method; On amplitude and phase place, there is error; Therefore the index that needs a kind of gauge signal range error comprehensively and phase error; On planisphere, error vector is the error degree of reaction signal clearly, therefore need utilize vector amplitude error (EVM:Error Vector Magnitude) parameter.

The EVM parameter-definition is an error signal power and all square ratio of reference signal power, representes with the percentage form.

The EVM parameter is the deviation between measuring-signal and the reference signal; In traditional method; Adopt algorithm to recover reference signal: at first will receive signal and carry out the reference signal that descrambling, despreading and phase place judgement obtain bit-level, through modulation, spread spectrum, scrambling, adding intermediate code, filtering obtains reference vector again; Error vector between reference metric vector and the measurement vector calculates the EVM desired value according to the EVM computing formula more then.The account form of this mode is complicated, and reference signal is definite on the reception basis of signals, when the error rate is high, can't judge then whether result of calculation is accurate.

Summary of the invention

Technical problem to be solved by this invention provides a kind of accuracy high satellite mobile communication terminal vector amplitude error measurement mechanism and method, can be applicable to the GMR satellite mobile communication system.

A kind of satellite mobile communication terminal vector amplitude error measurement mechanism is used for vector amplitude error (EVM) parameter of instrumented satellite GSM terminal signaling, and it is characterized in that: said measurement mechanism comprises input module; Output module, control module, EVM computing module; Satellite mobile communication protocol emulation terminal module; Satellite mobile communication protocol emulation base station module, duplex module, radio frequency processing module and interface module;

Input module links to each other with control module, and control module is accomplished the EVM computing module, satellite mobile communication protocol emulation terminal module, satellite mobile communication protocol emulation base station module, and the control of output module;

The EVM computing module produces reference vector and is sent to said pseudo-terminal module, receives first reference signal and second reference signal that said pseudo-terminal module is sent; Utilize first reference signal and the second reference signal compute vectors range error;

Satellite mobile communication protocol emulation terminal module is encoded to the reference vector that receives, modulation, and constellation mapping generates first reference signal, and this first reference signal is sent to the EVM computing module; First reference signal is carried out being sent to satellite mobile communication protocol emulation base station module after the filtering; Receive the reference signal of said anolog base station module passback, the reference signal of passback is carried out obtaining said second reference signal after the filtering, be sent to the EVM computing module with reference to letter said second;

Satellite mobile communication protocol emulation base station module and satellite mobile communication protocol emulation terminal module communicate; And control terminal to be measured passback reference signal;

Duplex module one end and satellite mobile communication protocol emulation base station module, the other end links to each other with the radio frequency processing module, accomplishes the two-way processing to sending and receiving;

The radio frequency processing module is accomplished signal is gone up down-converted;

Interface module is a radio frequency interface, and the one of which end links to each other through radio-frequency transmission line with terminal to be measured, and the other end links to each other with said radio frequency processing module.

Utilize said apparatus to carry out the method that vector amplitude error is measured:

At first import Testing requirement, comprise channel type, the work centre frequency through input module;

Under the control of control module, produce reference vector and mail to said pseudo-terminal module by the EVM computing module;

Said pseudo-terminal module is encoded to the reference vector that receives, modulation, and constellation mapping generates first reference signal, and this first reference signal is sent to the EVM computing module; First reference signal is carried out being sent to said anolog base station module after the filtering;

Filtered first reference signal that said anolog base station module will receive is sent to duplex module, arrives the radio frequency processing module through duplex module; And carry out up-conversion through the radio frequency processing module, send to terminal to be measured through interface module;

After the signal that end-on to be measured is received is handled and is reduced to reference vector, then this reference vector is handled the reference signal that obtains returning;

The reference signal of this passback arrives interface module through radio-frequency transmission line, sends into the radio frequency processing module through interface module and carries out down-converted and obtain the base band reference signal, and the base band reference signal is sent to said pseudo-terminal module through said anolog base station module;

Through said pseudo-terminal module the base band reference signal is carried out obtaining second reference signal after the filtering, said pseudo-terminal module sends to the EVM computing module with this second reference signal;

The EVM computing module utilizes first reference signal and the second reference signal compute vectors range error.

The present invention compared with prior art, advantage specific as follows:

(1) the present invention is through known forward direction reference signal, directly calculates with the reference signal of terminal to be measured passback, breaks away from the past that reference vector need carry out Calculation Method, reduced the error of calculation, improved vector amplitude error and measured accuracy.

(2) integrated simple base station and dumb terminal in the vector error measurement mechanism of the present invention only are used for satisfying the simulation of basic functions, and possess the ability of compute vectors range error.The present invention is through the simulation to mobile telecommunication channel, and the vector amplitude error of calculating and practical communication similar process satisfies the satellite mobile communication system testing requirement, is applicable to the GMR satellite mobile communication system, and is significant to practical engineering application.

(3) the present invention has fundamentally changed the method for measuring vector amplitude error.Upgraded the method that the method for recovering reference vector improves measuring accuracy than rely in the past, this device is provided with reference vector in advance, effectively prevents the influence of recovery algorithms to reference vector itself.

Description of drawings

Fig. 1 is that institute's invention measurement mechanism is formed sketch map.

Embodiment

Below in conjunction with accompanying drawing, the present invention is elaborated.

As shown in Figure 1, satellite mobile communication of the present invention terminal vector amplitude error measurement mechanism comprises like lower module:

Satellite mobile communication protocol emulation base station module: in order to measure the EVM parameter of satellite mobile communication terminal in the practical communication; Need simulate actual communication process; The anolog base station module satisfies basic communication requirement; Possess Speech Communication function and basic control function, can satisfy the mutual communication requirement at two terminals, but do not possess the access function of multiple terminals.The transmission receive channel of anolog base station module is single, is merely the communication requirement that adapts to two terminals.The anolog base station module also possesses the function through the signal of control signaling terminal to be measured passback appointment.

Satellite mobile communication protocol emulation terminal module: in order to measure the EVM parameter at the satellite mobile communication terminal in the practical communication; Need auxiliary termination function module; This pseudo-terminal module is used for simulating another terminal that is in the same point wave beam with terminal to be measured; Send communication request to anolog base station, send the known signal that the EVM computing module provides, make comparisons with the return path signal at terminal to be measured being used for.The pseudo-terminal module has burst catches, signal demodulating and decoding, modulating-coding, and the function of filtering.

Transmission duplex module: when anolog base station and terminal communication to be measured; Need when anolog base station and this terminal communication to be measured, possess transmission-receiving function simultaneously; Through the transmission duplex module signal being carried out transmit receive branching filter handles; One road signal is a signal of issuing terminal to be measured through the anolog base station module, and another road signal is the return path signal at terminal to be measured.

Radio frequency processing module: be used for radiofrequency signal is gone up down-converted, when receiving signal radiofrequency signal be adjusted into baseband signal, when sending signal baseband signal is modulated to radiofrequency signal.

Interface module: because communicating by letter between terminal to be measured and the measurement mechanism of the present invention need not propagate through antenna, thereby avoided of the influence of antenna receiving-sending performance, but passed through radio frequency interface module and the direct transmission signals of radio-frequency transmission line to EVM.The radiofrequency signal of radio frequency processing module output sends on the radio-frequency transmission line through interface module, is transferred to terminal to be measured through radio-frequency transmission line then.

EVM computing module: provide test vector to satellite mobile communication protocol emulation terminal module.

The test philosophy of vector amplitude error does, will receive reference signal Z, with known transmission reference signal R contrast, and error of calculation E=Z-R, again according to the computing formula of EVM:

$\mathrm{EVM}=\frac{\mathrm{RMS}\left(\right|E\left|\right)}{\mathrm{RMS}\left(\right|R\left|\right)}=\frac{\mathrm{RMS}\left(\right|Z-R\left|\right)}{\mathrm{RMS}\left(\right|R\left|\right)}\×100\%$

Calculate the EVM value.In this device to test process, only send frame data at every turn and receive frame data.

Input module is accomplished the input of paired domination number certificate, comprises channel type, work centre frequency etc.;

Output module is accomplished the Presentation Function to test data and current operation;

Control module is accomplished the EVM computing module, satellite mobile communication protocol emulation terminal module, the control of satellite mobile communication protocol emulation base station module and output module;

The present invention is used for the vector amplitude error of measuring terminals; During measurement; At first need terminal to be measured be connected with measurement mechanism of the present invention, concrete connected mode is for connecting through radio frequency interface, and terminal to be measured and measurement mechanism lay respectively at the two ends of radio frequency interface; Signal after the end output through radio frequency interface to radio-frequency transmission line, be transferred to the other end.

Hereinafter is defined as forward direction with the direction that device according to the invention mails to terminal to be measured, and relative vector is defined as reference vector (forward direction), and the direction that terminal to be measured is mail to this device is defined as passback, and relative vector is defined as reference vector (passback).

When measuring beginning, at first import this Testing requirement by input module (for example QWERTY keyboard), comprise channel type, the work centre frequency.Wherein channel type has determined the constellation mapping mode of signal, selects π/4-CQPSK, π/4-CBPSK, and π/4-DBPSK or 6-PSK, the work centre frequency is the headend frequency that the pseudo-terminal module in terminal to be measured and the measurement mechanism takies separately.This input process shows in output module (for example screen) all to some extent.

After the configuration information input, under the control of control module, produce reference vector (forward direction) by the EVM computing module, and mail to the pseudo-terminal module; The pseudo-terminal module processes reference vector (forward direction), mainly comprises coding, modulation; Constellation mapping, filtering forms and sends reference signal (forward direction).Detailed process mails to the EVM computing module for the signal of this reference signal (forward direction) after constellation mapping, the EVM computing module with this signal storage in buffer memory, as after the reference signal (forward direction) of compute vectors range error.Filtered reference signal mails to anolog base station in the pseudo-terminal module; Handle through anolog base station, add the control signaling, form downlink frame; And carry out up-conversion through the radio frequency processing module; Adjust to the tranmitting frequency in the practical application, send to terminal to be measured, and control passback reference signal in terminal to be measured through interface module.

After reference signal (forward direction) is received at terminal to be measured,, receive processing to received signal according to the signaling request of base station, be reduced to reference vector after, according to transmission flow reference vector is modulated to reference signal (passback).This reference signal (passback) arrives the interface module of measurement mechanism of the present invention through radio-frequency transmission line; After interface module receives reference signal (passback), send into the radio frequency processing module and carry out down-converted, become base band reference signal (passback); This base band reference signal (passback) is issued the anolog base station module; Add the control signaling by the anolog base station module, form downlink frame, issue the pseudo-terminal module.The pseudo-terminal module sends to the EVM computing module through Filtering Processing, and the base band reference signal (passback) of EVM computing module utilization passback and the transmission reference signal (forward direction) of storage are in advance handled together, and are used for the compute vectors range error.

Be that example is explained working method of the present invention with TCH 3 Traffic Channels below:

At first the user to set channel to be measured through input module be the TCH3 Traffic Channel, after control module receives the instruction from input module, the coding and the modulation system of TCH3 Traffic Channel are informed the anolog base station module, pseudo-terminal module and EVM module.Control module is informed the anolog base station module with the transmission and the receive frequency at terminal to be measured, in this example terminal to be measured is set in the 254th group of carrier wave, i.e. the dispatching centre frequency 1532937.50kHz at terminal to be measured, receiving center frequency 1634437.50kHz.

Send signaling by control module to the EVM computing module, indication test beginning, the EVM computing module produces one group of random data, and promptly reference vector sends to the pseudo-terminal module with reference vector; The pseudo-terminal module is encoded to reference vector, modulation, and π/4-CQPSK constellation mapping feeds back to the EVM computing module, and pseudo-terminal module continuation filtering forms reference signal (forward direction) and sends to the anolog base station module then; The anolog base station module receives reference signal, adds the control signaling to terminal to be measured, arrives the radio frequency processing module through duplex module in the lump; The radio frequency processing module is modulated to centre frequency 1634437.50kHz place to the signal up-conversion, sends to radio-frequency transmission line through interface module, sends terminal to be measured to through radio-frequency transmission line.

After terminal to be measured receives the signal that measurement mechanism of the present invention sends; Handle to the received signal, through down-conversion, filtering; π/4-CQPSK constellation inverse mapping; Demodulation, decoding reverts to reference vector, and the initial reference vector that this reference vector should provide with the EVM computing module in the measurement mechanism of the present invention is consistent; Encode to reference vector in terminal to be measured then, modulation, and mapping, filtering upconverts to centre frequency 1532937.50kHz place, passes back to measurement mechanism of the present invention through radio-frequency transmission line.

Measurement mechanism of the present invention receives the radiofrequency signal that send at terminal to be measured, through the radio-frequency module down-conversion, sends into the anolog base station module; The anolog base station module forwards is given the pseudo-terminal module, and the pseudo-terminal module is carried out filtering to the received signal, sends to the EVM computing module; Reference signal one union of passback reference signal that the EVM computing module will receive and transmission calculates the vector amplitude error at terminal to be measured, and in output module, shows.

Claims (2)

1. satellite mobile communication terminal vector amplitude error measurement mechanism is used for the vector amplitude error (EVM) of instrumented satellite GSM terminal signaling, and it is characterized in that: said measurement mechanism comprises input module; Output module, control module, EVM computing module; Satellite mobile communication protocol emulation terminal module; Satellite mobile communication protocol emulation base station module, duplex module, radio frequency processing module and interface module;

Input module links to each other with control module, and control module is accomplished the EVM computing module, satellite mobile communication protocol emulation terminal module, satellite mobile communication protocol emulation base station module, and the control of output module;

The EVM computing module produces reference vector and is sent to said pseudo-terminal module, receives first reference signal and second reference signal that said pseudo-terminal module is sent; Utilize first reference signal and the second reference signal compute vectors range error;

Satellite mobile communication protocol emulation terminal module is encoded to the reference vector that receives, modulation, and constellation mapping generates first reference signal, and this first reference signal is sent to the EVM computing module; First reference signal is carried out being sent to satellite mobile communication protocol emulation base station module after the filtering; Receive the reference signal of said anolog base station module passback, the reference signal of passback is carried out obtaining said second reference signal after the filtering, said second reference signal is sent to the EVM computing module;

Satellite mobile communication protocol emulation base station module and satellite mobile communication protocol emulation terminal module communicate, and control passback reference signal in terminal to be measured;

Duplex module one end and satellite mobile communication protocol emulation base station module, the other end links to each other with the radio frequency processing module, accomplishes the two-way processing to sending and receiving.

The radio frequency processing module is accomplished signal is gone up down-converted;

Interface module is a radio frequency interface, and the one of which end links to each other through radio-frequency transmission line with terminal to be measured, and the other end links to each other with said radio frequency processing module.

2. utilize the said device of claim 1 to carry out the method that vector amplitude error is measured, it is characterized in that:

At first import Testing requirement, comprise channel type, the work centre frequency through input module;

Under the control of control module, produce reference vector and mail to said pseudo-terminal module by the EVM computing module;

Said pseudo-terminal module is encoded to the reference vector that receives, modulation, and constellation mapping generates first reference signal, and this first reference signal is sent to the EVM computing module; First reference signal is carried out being sent to said anolog base station module after the filtering;

Filtered first reference signal that said anolog base station module will receive is sent to duplex module, arrives the radio frequency processing module through duplex module; And carry out up-conversion through the radio frequency processing module, send to terminal to be measured through interface module;

After the signal that end-on to be measured is received is handled and is reduced to reference vector, then this reference vector is handled the reference signal that obtains returning;

The reference signal of this passback arrives interface module through radio-frequency transmission line, sends into the radio frequency processing module through interface module and carries out down-converted and obtain the base band reference signal, and the base band reference signal is sent to said pseudo-terminal module through said anolog base station module;

Through said pseudo-terminal module the base band reference signal is carried out obtaining second reference signal after the filtering, said pseudo-terminal module sends to the EVM computing module with this second reference signal;

The EVM computing module utilizes first reference signal and the second reference signal compute vectors range error.

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