CN102665229B - Testing platform and testing method for WLAN product - Google Patents
Testing platform and testing method for WLAN product Download PDFInfo
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Abstract
The invention relates to a testing platform for a WLAN (Wireless Local Area Network) product, which comprises a WLAN testing transmitting system and a WLAN testing receiving system, wherein the WLAN testing transmitting system comprises a radio frequency transmitter testing module and a transmitting signal hardware processing module; and the WLAN testing receiving system comprises a radio frequency receiver testing module and a receiving signal hardware processing module. Correspondingly, the invention also relates to a testing method for the WLAN product. In the testing method, by a series of steps, the testing platform for the WLAN product, which is designed by the invention, is called to test the WLAN product so as to evaluate the advantages and disadvantages of the WLAN product.
Description
Technical field
The present invention relates to a kind of Wireless LAN Equipments test platform and method of testing thereof.
Background technology
Over nearly 20 years, wireless communication technology is advanced by leaps and bounds, the distance having furthered rapidly between people.In the end of the year 2007, Ministry of Industry and Information of China issues 3G (3rd Generation) licence plate, has formally pulled open the curtain in 3G epoch.According to statistics, in the end of the year 2011, the 3G subscription number of China has broken through 1.28 hundred million, expects the end of this year these data and will exceed 300,000,000, continues to present the impetus of blowout.What the sharply rising of mobile subscriber's quantity brought is that data volume breaks out and the problem of existing bandwidth wretched insufficiency.Certainly, these problems can temporarily be covered by network upgrade and bandwidth dilatation, but for telex network and the mobile Internet access of peak period, depend the raw mode improving equipment alone and cannot meet these business demands, and will face huge cost pressure.And in the traffic carrying capacity of mobile communication, have 70% to produce at indoor nomadic state, so WLAN (wireless local area network) (is called for short to WLAN, being the abbreviation of Wireless Local Area Network) technology supplements and upgrading as mobile communication, just can solve well the difficult problem of transmission rate, bandwidth tolerance limit and facility cost.
Taking WCDMA as example, realizing HSDPA (high speed downlink packet access) afterwards, theoretical downstream rate side reaches 7.2Mbps, and three kinds, this or China theoretical speed of download of 3G network present stage is the highest, and other is if TD-SCDMA and CDMA2000 are only about 3Mbps; And WLAN just than outstanding many, with regard to its main product 802.11g, the theoretical maximum of transmission rate is 54Mbps, actual speed is generally also between 16-30Mbps.These than 3G network fast upper 10 times, flow cost has but reduced nearly seventy percent simultaneously.As for construction cost also than 3G network low half.
In addition, the two uses regional complementarity.The coverage property of 3G is suitable for wide area and metropolitan area, supports high-speed mobile; WLAN is suitable for metropolitan area focus and indoor environment.Therefore, the senior executive of Duo Jia operator all to represent to add WLAN in different occasions be the optimal solution that 3G technology is alleviated the immense pressure that the wireless data traffic that grows with each passing day causes network.
As can be seen here, WLAN (wireless local area network) is not eliminated because of scientific and technological development, has shone on the contrary brand-new life under the overall background in 3G epoch.Therefore can expect, in the coming years, the output of commercial Wireless LAN Equipments (as wireless network card etc.) will significantly promote, and what bring thus is the problem that how to ensure properties of product.This comprises correct generation and the transmitting of wireless signal, the information in reception, recovery and analytic signal etc.This just makes commercial product before the sale of dispatching from the factory, must be through tight test process, to guarantee that the above link can not make a mistake.So, just require a radio frequency transceiver that conforms with local area network communication standard as test platform, be used for and other products between transmit wireless signal, reached test its performance object.
In numerous WLAN standard, IEEE 802.11g is undoubtedly nowadays most widely used agreement.Compared with 802.11 consensus standards before, it has two main features: it uses OFDM modulation (OFDM) technology in 2.4GHz frequency range, makes more than message transmission rate brings up to 20Mbps; 802.11g standard can interconnect with the system of 802.11b, coexists in same WAP (wireless access point) (AP) network, and new standard is still supported DSSS/CCK technology, has ensured backwards compatibility.Original like this wlan system can be level and smooth to the transition of high-speed radio local area network (LAN), extended the useful life of IEEE 802.11b product, reduce user's investment.
Therefore, the quality of measuring for Wireless LAN Equipments has determined the development and utilization of Wireless LAN Equipments, but existing measuring technique not only cannot precisely realize and measuring parameter, and measuring process is loaded down with trivial details, has brought inconvenience to measurement.
Summary of the invention
Technical problem to be solved by this invention is to provide one and is applied in radio communication and apparatus measures field, is applicable to the Wireless LAN Equipments test platform of the performance test of commercial wireless network product.
Corresponding therewith, another technical problem that will solve of the present invention is to provide one and is applied in radio communication and apparatus measures field, is applicable to the method for testing of the Wireless LAN Equipments of the performance test of commercial wireless network product.
The present invention is in order to solve the problems of the technologies described above by the following technical solutions: the present invention has designed a kind of Wireless LAN Equipments test platform, comprises Wireless LAN testing emission system and Wireless LAN testing receiving system; Described Wireless LAN testing emission system comprises radio frequency sending set test module and the hardware processing module that transmits, radio frequency sending set test module converts data to be transmitted, form baseband complex signal, the hardware processing module of transferring to transmit is processed and is generated radio magnetic wave, and launches by antenna; Described Wireless LAN testing receiving system comprises radio-frequency transmitter test module and receives signal hardware processing module, receive signal hardware processing module by antenna reception radio magnetic wave, and process and obtain receiving sequence, pass to again radio-frequency transmitter test module and carry out corresponding inverse transformation, restore information.
As a preferred technical solution of the present invention: described in the hardware processing module that transmits comprise radio-frequency signal generator, described radio-frequency signal generator comprises vector modulator, signal generator and continuous wave generator; Described reception signal hardware processing module comprises rf signal analysis instrument, and described rf signal analysis instrument comprises low-converter, 16Bit if digitization instrument and continuous wave generator.
Corresponding therewith, the present invention is in order to solve the problems of the technologies described above by the following technical solutions: the present invention has designed a kind of method of testing of Wireless LAN Equipments, comprises the steps:
Steps A. generate a group data stream and simulate the frame of MAC layer by PN sequence generator, as armed information, and the working frequency range of selected data transmission rate and radiofrequency signal;
Data flow described in Wireless LAN Equipments transmitting to be measured receiving step A for step B., calculates bit information error rate;
The also data flow described in receiving step A of Wireless LAN Equipments test platform transmitting of the present invention's design for step C., calculates equally bit information error rate, and records the radio frequency parameter in radio-frequency transmitter test module;
Data flow described in the Wireless LAN testing emission system step of transmitting A of the present invention's design for step D., and with Wireless LAN Equipments reception signal to be measured, observe the variation of bit information error rate;
Step e. by data flow described in Wireless LAN Equipments step of transmitting A to be measured, and with Wireless LAN testing receiving system reception signal, observe bit information error rate, and record the radio frequency parameter in radio-frequency transmitter test module;
Step F. finally related data is compared, according to the quality of protocol of wireless local area network design code evaluation Wireless LAN Equipments to be measured, obtain data results.
As a preferred technical solution of the present invention: in described step F, related data comprises bit information error rate, radio frequency parameter, frame synchronization moment position, spectrogram and planisphere.
As a preferred technical solution of the present invention: described radio frequency parameter comprises that low-converter gain, outside gain, frequency mixer level, intermediate frequency power output, rf attenuation and intermediate frequency decay.
As a preferred technical solution of the present invention: described data results comprises frame synchronization moment position, bit information error rate, time domain waveform figure, spectrogram, planisphere and error message.
As a preferred technical solution of the present invention: in described Wireless LAN Equipments method of testing, transmitting-receiving data flow is ERP-OFDM pattern; Wherein data streams comprises: first successively the frame of MAC layer is carried out framing, scrambling, convolutional encoding, interweaved and mapping, inverse fast Fourier transform and interpolation protection interval by radio frequency sending set test module, then by transmit hardware processing module to signal arrange the modulation of waveform, IQ road, high power amplifies, and sends by antenna; Receiving data stream comprises: receive signal hardware processing module by antenna reception radio magnetic wave; and radio magnetic wave is carried out to linear prower amplifier HeIQ road successively and detects, then by radio-frequency transmitter test module successively to signal carry out synchronously, channel estimating, equilibrium, deletion protect that interval, fast Fourier transform, inverse mapping deinterleave, decoding, descrambling and parse for frame.
As a preferred technical solution of the present invention: under described ERP-OFDM pattern, in transmitting data flow step, also comprise the pilot sub-carrier operation between map operation and inverse fast Fourier transform operation.
As a preferred technical solution of the present invention: described interpolation protection is spaced apart the data Replica of 16 bits after each OFDM symbol to before this symbol, forms prefix, at the unremitting Nature Link in interface point place; Described removal protection is spaced apart the data of initial 16 bits of removing each OFDM symbol.
As a preferred technical solution of the present invention: in described Wireless LAN Equipments method of testing, transmitting-receiving data flow is ERP-DSSS/CCK pattern, wherein data streams comprises: first successively the frame of MAC layer is carried out to framing, scrambling, coding and spread spectrum by radio frequency sending set test module, then by transmit hardware processing module to signal carry out the modulation of IQ road, high power amplifies, and send by antenna; Receiving data stream comprises: receive signal hardware processing module by antenna reception radio magnetic wave, and radio magnetic wave is carried out to linear prower amplifier HeIQ road successively and detects, then by radio-frequency transmitter test module successively to signal carry out synchronously, channel estimating, equilibrium, despreading, decoding, descrambling and parse for frame.
To sum up, a kind of Wireless LAN Equipments test platform of the present invention and method of testing thereof adopt above technical scheme compared with prior art, have following technique effect:
(1) the present invention has realized a Wireless LAN Equipments test platform based on virtual instrument technique, and this platform is to design under the specification that meets WLAN (wireless local area network);
(2) native system can be tested the WLAN terminal on market, receives by mutual the sending out mutually of signal, observes, compares radio frequency parameter and data results, comprehensively passes judgment on properties of product;
(3) the Wireless LAN Equipments test platform self of the present invention design also can complete the transmission of wireless signal, and the standard of the design specification adhere rigidly to WLAN (wireless local area network) of this test platform, therefore can with the intercommunication of other standards Realization of Product.
Brief description of the drawings
Fig. 1 is the integrated stand composition of Wireless LAN Equipments test platform data streams in the present invention;
Fig. 2-1st, the system block diagram of data streams under ERP-OFDM pattern in the present invention;
Fig. 2-2nd, the system block diagram of receiving data stream under ERP-OFDM pattern in the present invention;
Fig. 3 is the data scrambler of ERP-OFDM system in the present invention;
Fig. 4 is the convolution coder of ERP-OFDM system in the present invention;
Fig. 5 is the remaining and insertion dummy argument process of deleting that in the present invention, encoding rate is R=3/4;
Fig. 6-1st, adopts the modulating-coding planisphere of BPSK modulation system in the present invention;
Fig. 6-2nd, adopts the modulating-coding planisphere of QPSK modulation system in the present invention;
Fig. 6-3rd, adopts the modulating-coding planisphere of 16-QAM modulation system in the present invention;
Fig. 6-4th, adopts the modulating-coding planisphere of 64-QAM modulation system in the present invention;
Fig. 7-1st, the system block diagram of data streams under ERP-DSSS/CCK pattern in the present invention;
Fig. 7-2nd, the system block diagram of receiving data stream under ERP-DSSS/CCK pattern in the present invention;
Fig. 8 is the data scrambler of ERP-DSSS/CCK system in the present invention;
Fig. 9 is the data de-scrambling device of ERP-DSSS/CCK system in the present invention;
Figure 10 is sliding window schematic diagram in the present invention;
Figure 11 is thick synchronization program figure in the present invention;
Figure 12 is the smart synchronization program based on ERP-OFDM frame preamble code in the present invention;
Figure 13 is correlator configuration figure in the present invention;
Figure 14 is the smart synchronization program based on ERP-DSSS/CCK frame preamble code in the present invention;
Figure 15 is the channel estimation module of ERP-OFDM pattern in the present invention;
Figure 16 is the schematic diagram of auto-adaptive fir filter in the present invention;
Figure 17 is the channel estimation module of ERP-DSSS/CCK pattern in the present invention;
Figure 18 is the workflow diagram of modular instrument in the present invention;
Figure 19 is transmitter driver in the present invention;
Figure 20 is receiver driver in the present invention;
Figure 21 is the schematic diagram that adds protection interval operation in the present invention.
Embodiment
Below in conjunction with Figure of description, the specific embodiment of the present invention is described in further detail.
As shown in Figure 1, the present invention has designed one and has been applied in radio communication and apparatus measures field, is applicable to the Wireless LAN Equipments test platform of the performance test of commercial wireless network product.
Corresponding therewith, another technical problem that will solve of the present invention is to provide one and is applied in radio communication and apparatus measures field, is applicable to the method for testing of the Wireless LAN Equipments of the performance test of commercial wireless network product.
The present invention is in order to solve the problems of the technologies described above by the following technical solutions: the present invention has designed the present invention and designed a kind of Wireless LAN Equipments test platform, comprises Wireless LAN testing emission system and Wireless LAN testing receiving system; Described Wireless LAN testing emission system comprises radio frequency sending set test module and the hardware processing module that transmits, radio frequency sending set test module converts data to be transmitted, form baseband complex signal, the hardware processing module of transferring to transmit is processed and is generated radio magnetic wave, and launches by antenna; Described Wireless LAN testing receiving system comprises radio-frequency transmitter test module and receives signal hardware processing module, receive signal hardware processing module by antenna reception radio magnetic wave, and process and obtain receiving sequence, pass to again radio-frequency transmitter test module and carry out corresponding inverse transformation, restore information.
As a preferred technical solution of the present invention: described in the hardware processing module that transmits comprise radio-frequency signal generator, described radio-frequency signal generator comprises vector modulator, signal generator and continuous wave generator; Described reception signal hardware processing module comprises rf signal analysis instrument, and described rf signal analysis instrument comprises low-converter, 16Bit if digitization instrument and continuous wave generator.
A kind of Wireless LAN Equipments test platform of the present invention's design is in concrete enforcement, described transmitting in hardware processing module and reception signal hardware processing module, radio-frequency signal generator is that NI PXIe-5673E, rf signal analysis instrument are that NI PXIe-5663, vector modulator are that NI PXIe-5611, signal generator are that NI PXIe-5450, continuous wave generator are that NI PXI-5652, low-converter are that NI PXIe-5601,16Bit if digitization instrument are NI PXIe-5622.
NI PXIe-5673E is the RF Vector Signal Generator that a centre frequency reaches as high as 6.6GHz, can produce the instant bandwidth of 100MHz and the transmitting power of 10dBm.By means of NI PXIe-5673E, can generate different waveforms, comprise all kinds of modulated waveforms, Multjtone and other random waveforms.It is made up of NI PXIe-5611 vector modulator, NI PXIe-5450 signal generator and NI PXI-5652 continuous wave generator.NI PXIe-5663 rf signal analysis instrument can provide highest frequency to reach the Vector Signal Analysis ability of 26.5GHz and 50MHz instant bandwidth, powerful protection against noise interference characteristic also makes it win good reputation: when frequency is during in 800MHz, phase noise is only-129dBc/Hz; While being positioned at 1GHz, also can not exceed-165dBm/Hz makes an uproar at the end.Identical with signal generator, it is also made up of three radio frequency boards, is respectively NI PXIe-5601 low-converter, NI PXIe-562216Bit if digitization instrument and NI PXI-5652 continuous wave generator.Here NI PXI-5652 continuous wave generator and NI PXIe-5673E radio-frequency signal generator are all used to provide local oscillation signal, and require the same homophase frequently of carrier wave of the generation on both sides.
Corresponding therewith, the present invention is in order to solve the problems of the technologies described above by the following technical solutions: the present invention has designed a kind of method of testing of Wireless LAN Equipments, comprises the steps:
Steps A. generate a group data stream and simulate the frame of MAC layer by PN sequence generator, as armed information, and the working frequency range of selected data transmission rate and radiofrequency signal;
Data flow described in Wireless LAN Equipments transmitting to be measured receiving step A for step B., calculates bit information error rate;
The also data flow described in receiving step A of Wireless LAN Equipments test platform transmitting of the present invention's design for step C., calculates equally bit information error rate, and records the radio frequency parameter in radio-frequency transmitter test module;
Data flow described in the Wireless LAN testing emission system step of transmitting A of the present invention's design for step D., and with Wireless LAN Equipments reception signal to be measured, observe the variation of bit information error rate;
Step e. by data flow described in Wireless LAN Equipments step of transmitting A to be measured, and with Wireless LAN testing receiving system reception signal, observe bit information error rate, and record the radio frequency parameter in radio-frequency transmitter test module;
Step F. finally related data is compared, according to the quality of protocol of wireless local area network design code evaluation Wireless LAN Equipments to be measured, obtain data results.
Wherein, calculating bit information error rate is that transmitting terminal records information to be launched by global variable; Receiving terminal draws information sequence after resolving and receiving signal, and the two is isotopic number more not, draws bit information error rate BER.
As a preferred technical solution of the present invention: in described step F, related data comprises bit information error rate, radio frequency parameter, frame synchronization moment position, spectrogram and planisphere.
As a preferred technical solution of the present invention: described radio frequency parameter comprises that low-converter gain, outside gain, frequency mixer level, intermediate frequency power output, rf attenuation and intermediate frequency decay.
As a preferred technical solution of the present invention: described data results comprises frame synchronization moment position, bit information error rate, time domain waveform figure, spectrogram, planisphere and error message.
As shown in Fig. 2-1,2-2, as a preferred technical solution of the present invention: in described Wireless LAN Equipments method of testing, transmitting-receiving data flow is ERP-OFDM pattern; Wherein data streams comprises: first successively the frame of MAC layer is carried out framing, scrambling, convolutional encoding, interweaved and mapping, inverse fast Fourier transform and interpolation protection interval by radio frequency sending set test module, then by transmit hardware processing module to signal arrange the modulation of waveform, IQ road, high power amplifies, and sends by antenna; Receiving data stream comprises: receive signal hardware processing module by antenna reception radio magnetic wave; and radio magnetic wave is carried out to linear prower amplifier HeIQ road successively and detects, then by radio-frequency transmitter test module successively to signal carry out synchronously, channel estimating, equilibrium, deletion protect that interval, fast Fourier transform, inverse mapping deinterleave, decoding, descrambling and parse for frame.
" PLCP " of data streams refers to framing, and the frame that is MAC layer adds frame head, comprises the lead code of receiver for synchronous and channel estimating in frame head, also has the information such as speed, length of mac frame; " PLCP " of receiving data stream refers to parse for frame, removes the frame head adding before, again obtains the frame of MAC layer; " HPA ": high power amplifier is amplified to low level signal the desired high power levels of long-distance transmissions, to prevent from occurring the excessive exhaustion of signal power in transmitting procedure on transmitter; " LPA ": linear power amplifier, refer to the amplifier that the amplitude of output signal is directly proportional to input signal amplitude, be used for input signal to be amplified to the power level place needing; " add GI " and add protection interval.
As a preferred technical solution of the present invention: described interpolation protection is spaced apart the data Replica of 16 bits after each OFDM symbol to before this symbol, forms prefix, at the unremitting Nature Link in interface point place; Described removal protection is spaced apart the data of initial 16 bits of removing each OFDM symbol.Because the signal transmission of ERP-OFDM emission mode is a series of OFDM symbol, transmitted in mutually orthogonal subchannel by 64 subcarriers successively, and each OFDM symbol has 64.In order farthest to eliminate intersymbol interference, can before each OFDM symbol, insert a segment information as protection interval (Guard Interval, GI), but the interchannel interference that can bring like this destroys the orthogonality between subchannel.So adopt the protection interval of Cyclic Prefix (Cyclic Prefix) form; as shown in figure 21; by the data Replica of 16 bits after each OFDM symbol to before this symbol; form prefix; at the unremitting Nature Link in interface point place; like this, OFDM symbol 64+16=80 bit (1 bit=1) altogether, removal GI namely removes the data of initial 16 bits of each OFDM symbol.
Wherein, for the Wireless LAN Equipments test platform data streams of ERP-OFDM pattern:
(1) scrambling and descrambling
Data field will be through the scrambling of scrambler before encoding, and the generator polynomial of scrambler is as follows, and structure as shown in Figure 3.
S (x)=x
7+ x
4+ 1 formula 1
Plus sige in figure represents XOR.Before scrambling, the initial condition of scrambler should be made as pseudo-random non-zero value, needs equally a descrambler to carry out restoring data at receiving terminal, and the structure of descrambler is identical with scrambler, for data are not made mistakes, also will ensure the synchronism of scrambling, descrambling.
(2) convolutional encoding
The object of convolutional encoding be make in each OFDM symbol, there is half, 1/3 or 1/4 position is the redundant digit for error correction.Encoding rate depends on the speed of data, refers to table 2.1.The generator polynomial that convolution coder adopts is g
0=O133, g
1=O171, wherein O represents octal number, the structure of encoder is as Fig. 4.The data that are labeled as " A " being positioned at data " B " before in the time that encoder is exported.In the time that encoding rate is 1/2, the data of output are coded data; If 2/3 or 3/4, need to adopt " deleting remaining " technical side can obtain coded data; Accordingly, receiver is wanted first to insert dummy argument " 0 " in original deleted position, then decoding in the time of decoding.The general viterbi algorithm that adopts of decoding, Fig. 5 has illustrated in the time that encoding rate is 3/4, deletes the remaining step with inserting dummy argument.
(3) data interlacing
Data after coding also will, through twice displacement, be called data interlacing.Each coding figure place N with single OFDM symbol
cBPSfor the length interweaving.Displacement for the first time guarantees that adjacent bits of coded is mapped on non-conterminous subcarrier; Displacement for the second time guarantees that adjacent bits of coded is alternately mapped in the high significance bit and low order of planisphere, to avoid the long-time appearance of the mapping (enum) data that only has low order.Equally, receiving terminal also needs the contrary interleaving process of two step displacements.
Twice displacement interweaving depends on respectively following two formula:
I=(N
cBPS/ 16) (kmod 16)+floor (k/16) k=0,1 ..., N
cBPS-1 formula 2
J=s × floor (i/s)+(i+N
cBPS-floor (16 × i/N
cBPS)) mod si=0,1 ..., N
cBPS-1 formula 3 in above two formulas, the numbering before k represents to interweave, i is the sequence number after replacing for the first time, j is the order after having interweaved, s is determined by following formula.
S=max (N
bPSC/ 2,1) formula 4
(4) modulation mapping
The subcarrier of OFDM can adopt the modulation system of BPSK, QPSK, 16-QAM, 64-QAM, and speed is depended in concrete selection equally.The planisphere that modulation adopts, as shown in Fig. 6-1,6-2,6-3,6-4, these mapping relations are that data, after ovennodulation, can be mapped as a sequence of complex numbers, i.e. { the form of d|I+jQ} according to the principle design of Gray code.For the mapping to all can obtain identical average power, need to be multiplied by normalized factor k to sequence of complex numbers
mOD, k
mODdetermine according to modulation system, refer to table 1.
The corresponding relation of table 1 normalization factor and modulation system
As a preferred technical solution of the present invention: under described ERP-OFDM pattern, in transmitting data flow step, also comprise the pilot sub-carrier operation between map operation and inverse fast Fourier transform operation.
In order to ensure in occurrence frequency skew or exist phase noise to disturb in the situation that, receiver still can carry out stable relevant detection, need in OFDM symbol, insert 4 pilot signals.It is in-21 ,-7,7,21 sub-carrier positions that these 4 pilot signals are inserted in respectively label.For several continuous OFDM symbols, the polarity of the pilot tone that adjacent-symbol inserts is also different, and the polarity of pilot tone is by initial condition entirely by the output sequence of the scrambler of " 1 " is determined, this sequence is a periodic sequence that length is 127 points.Certainly, this sequence will be passed through necessary cyclic extensions, to mate the number of OFDM symbol.After inserting pilot tone, the data that obtain just can, by 64 bit groupings, then have been carried out inverse fast Fourier transform IFFT.
As shown in Fig. 7-1,7-2, as a preferred technical solution of the present invention: in described Wireless LAN Equipments method of testing, transmitting-receiving data flow is ERP-DSSS/CCK pattern, wherein data streams comprises: first successively the frame of MAC layer is carried out to framing, scrambling, coding and spread spectrum by radio frequency sending set test module, then by transmit hardware processing module to signal carry out the modulation of IQ road, high power amplifies, and send by antenna; Receiving data stream comprises: receive signal hardware processing module by antenna reception radio magnetic wave, and radio magnetic wave is carried out to linear prower amplifier HeIQ road successively and detects, then by radio-frequency transmitter test module successively to signal carry out synchronously, channel estimating, equilibrium, despreading, decoding, descrambling and parse for frame.
Wherein, for the Wireless LAN Equipments test platform data streams of ERP-DSSS/CCK pattern:
(1) scrambling and descrambling
The frame of physical layer, before band spectrum modulation, need to pass through scrambler, and as shown in Figure 8, the generator polynomial of scrambling is structure
G (x)=z
-7+ z
-4+ 1 formula 5
For long PLCP, the initial condition of scrambler is [110 1100], wherein z
1=1 ..., z
7=0.And the PLCP of short lead code is in contrast, with [0,011 011] to scrambler initialization.
Because the feedback configuration between scrambler and descrambler is synchronous, so receiving terminal needn't be known the initial condition of scrambler in advance.Descrambling multinomial is identical with scrambling, and the structure of descrambler is as Fig. 9, and certainly, this is not unique structure.
For the scrambling/descrambling operation under ERP-OFDM pattern and ERP-DSSS/CCK pattern, according to the transmission rate of selected data, determined which kind of pattern of this data acquisition, the concrete principle of correspondence is: " ERP-OFDM pattern " comprises 6,9,12,18,24,36,48,54; " ERP-DSSS/CCK pattern " comprises 1,2,5.5,11, and unit is Mbps.Apply respectively the scrambling/descrambling operation under different mode.
(2) basis modulation and spread spectrum
ERP-DSSS/CCK has specified four kinds of speed and corresponding modulation system.Basic access speed (1Mbps, 2Mbps) has adopted the modulation system of differential phase keying (DPSK) and high speed chip spread spectrum; Spreading rate be based on CCK modulation technology the data rate of 5.5Mbps and 11Mbps, mode separately will be described respectively below.
Differential phase keying (DPSK) is the basis of DSSS system.It is encoded to data with the phase difference of signal transmission.Therefore the absolute phase of waveform is unimportant, importantly the difference of phase place.It can overcome the problem of separating timing phase inversion.In DSSS system, 1Mbps has adopted the modulation system of DBPSK, and 2Mbps is DQPSK.The coding schedule of the two is respectively shown in table 2 and table 3.
Table 2 1Mbps DBPSK coding schedule
| Input bit | Phase difference |
| 0 | 0 |
| 1 | π |
Table 3 2Mbps DQPSK coding schedule
| Dibit pattern | Phase difference |
| 00 | 0 |
| 01 | π/2 |
| 11 | π |
| 10 | 3π/2(-π/2) |
Data after coding utilize the Barker code of 11 to expand its frequency spectrum:
+1，-1，+1，+1，-1，+1，+1，+1，-1，-1，-1
Output order is from left to right, and first code element is alignd with a starting point that sends symbol, and the duration of each spread spectrum is 11 Baud Lengths.
(3) CCK modulation
The extended code length of CCK modulation is 8 and based on complement form, in 802.11g, obtains this 8 plural code words by following formula:
formula 6
In formula, c is code word, c={c
0..., c
7, c
0send at first, therefore, as long as obtain
can obtain the extended code of output.Wherein
to adjust whole sequence initial phase, by the front two d of input message
0, d
1determine d
0, d
1encode based on DQPSK, obtain
coding rule defines as table 4, and the variation of phase place is by counterclockwise rotation.Because be differential coding, so
phase place change with previous symbol
relevant.For first CCK symbol of PSDU, it
just depend on the phase place of last symbol of PLCP head above.
Table 4 DQPSK coding schedule
| d 0，d 1 | Even sign change phase place | Odd symbol variation phase |
| 00 | 0 | π |
| 01 | π/2 | 3π/2(-π/2) |
| 11 | π | 0 |
| 10 | 3π/2(-π/2) | π/2 |
All the other of an input message common value that determines three phase places of residue.Rule is as follows:
For 5.5Mbps, data, with 4 bit groupings, are encoded, and each grouping is d
0, d
1, d
2, d
4.D
0, d
1as mentioned above, d
3, d
4by following three formula, calculate
with
formula 7
Table 5QPSK coding schedule
| Data dibit (d i，d i+1) | Phase place |
| 00 | 0 |
| 01 | π/2 |
| 10 | π |
| 11 | 3π/2(-π/2) |
In the time that speed is 11 Mbps, produce the information data that each CCK symbol needs 8 bits, i.e. d
0, d
1, d
2, d
3, d
4, d
5, d
6, d
7, front two produces phase place according to table 4 equally
rear six groupings between two, form data dibit (d
2, d
3), (d
4, d
5), (d
6, d
7), then the QPSK specifying according to table 5 is respectively encoded to
with
note the difference of table 5 and table 3, what adopt here is binary coding, but not Gray code.
Calculate after four phase places according to table 4 and table 5, in substitution formula 6, just can draw the spread spectrum code character of CCK, head and the tail form the plural bit stream before transmitting after connecting successively.
For " detection of IQ road ", corresponding to " modulation of IQ road " of radio frequency sending set test module, what radio frequency sending set test module produced is baseband complex signal, " modulation of IQ road " is to extract real part and imaginary part, form respectively I road and Q road, then IQ two paths of signals is modulated respectively, form electromagnetic wave, still stack up according to plural form, then transmitting.Radio-frequency transmitter test module will carry out " detection of IQ road " to received signal, demodulation again after the electromagnetic wave on separation I road and Q road, reduction baseband complex signal.
As shown in Fig. 2-2,7-2, for Wireless LAN Equipments test platform receiving data stream:
1. simultaneous techniques
(1) slightly synchronous
In realization, frame synchronization can be divided into again thick synchronous and smart synchronous.Slightly synchronously do not need reference sequences, the principle of employing remains the variation according to list entries power, in the time that useful signal enters receiver, because its power is apparently higher than the power of noise in surrounding environment, so the performance number of list entries can be undergone mutation.At this moment just can determine the noise sequence that is sampled as before performance number sudden change, the scope of both having dwindled frame initial time after removal, has reduced smart synchronous computing, has also improved the latter's accuracy.
Slightly synchronously can pass through two synchronous slide window implementation, as shown in figure 10.Two identical windows of size keep constant window gap, slide backward from the starting point of receiving sequence with identical step-length, and the performance number of the interior short sequence of window separately is once just calculated in every movement, and two values are compared.If pre-sampled point is abundant, the front end of receiving sequence must have noise, also just means that the power ratio of two windows is infinitely close to 1 while starting; In the time that useful signal progressively enters the tail end of window 2, the power ratio of two windows is no longer 1.Experiment shows, as long as there is the sampled point of 1,2 useful signal to enter window 2, its power can far exceed the performance number of window 1 short-and-medium sequence at once.Because two windows have an overlay segment, so difference power must be the sequence generation in the first two window gaps, because of a scope that window gap is exactly useful signal original position after this.
Thick synchronization program based on LabVIEW as shown in figure 11.The length of two sliding windows is 50, and step-length is 10, and window gap is also 10, in the time that the power ratio of two windows is less than decision value, can determine that the initial time of frame has entered in preset range, now stop circulation, intercept the sequence after window 1, further obtain concrete original position.
(2) essence is synchronous
In the frame of ERP-OFDM, comprise 10 Short Training periodic sequences, 16 points of each sequence, amount to 160 points.Here utilized just periodicity and the autocorrelation of short training sequence to realize smart synchronous computing.
Noise signal is random signal, and random signal due to can not repeat produce, therefore noise signal can not and other sequences between produce correlation, there is not cross-correlation.So while carrying out related calculation with the noise sequence of 16 points or noise, useful signal mixed sequence and short training sequence, its correlation must be less than the cross correlation value between short training sequence.Therefore, can progressively remove remaining noise samples point by sliding window equally.Can be referring to Figure 12 according to the smart synchronization program based on ERP-OFDM frame preamble code of this principle design.
In program, the length of two sliding windows is all 144, is the total length of 9 short training sequences; Window gap is 16; In addition sliding step is 1.Obviously, when first window has loaded first 9 of 10 Short Training periodic sequences just, when another must load the sequence in rear 9 cycles, the cross correlation value maximum of two windows.Now the original position of first window is exactly the beginning of complete frame data.Certainly, this is to remove the relative position after partial noise, and before therefore adding, " rough position " of thick synchronous output is the accurate moment that simultaneous operation draws.In the drawings, two windows start to slide backward from the first place of the result sequence of thick synchronous output, each slip all will be calculated the cross correlation value of two short sequences in window, pass through again and previous comparison, higher value is left in register, and the original position of first window in corresponding moment of larger correlation is recorded in variable " relative position ".After several times slide, the value of finally staying in variable has been exactly the synchronous result of essence.Finally, according to relative position, again remove noise residual in receiving sequence, output signal sequence.
No matter the frame of ERP-DSSS/CCK form adopts the modulating mode of which kind of speed, and its lead code is all with the Barker code expansion of 11, therefore in the time receiving, will utilize well the autocorrelation of Barker code.The essence of ERP-DSSS/CCK pattern synchronously realizes based on this principle.
Checking correlation just need to be used correlator, and the correlator configuration based on 11 Barker codes as shown in figure 13.Receiving sequence is exported 1bit in shift register at every turn, and the data and the contraposition of Barker code word that are shifted in rear 11 registers are multiplied each other at every turn, more cumulative summation, as this output.
In the time that the lead code SYNC field through spread spectrum is alignd with 11 Barker code head and the tail in correlator, cross-correlation obtains maximum, and this maximum can be every 11 appearance once, this be because lead code after 11 translations, expanding by character late 11 bits that form can there is the situation that head and the tail align again with Barker code, therefore presents periodically.If contain noise in 11 registers of correlator, the Barker code frequency expansion sequence not matching with fixed codeword in other words conj.or perhaps, the output of correlator all there will not be crest.So, when multiple all after dates appear continuously in correlation peak, just can judge that first of correlator list entries of first peak value of generation is exactly first Bit data of PPDU.Record its label in receiving sequence, certainly, this is also " relative position " of a relative and thick synchronized result.
As shown in figure 14, this section of program is divided into three parts, and pseudo-peak is adjudicated and gone to correlator, peak value.Correlator comprises related operation and asks mould, related operation to utilize loop body to get successively " thick synchronized result " 11, cumulative summation after multiplying each other with 11 Barker code step-by-steps; Delivery is asked energy more subsequently.Now observe the waveform of correlation, have some continuous crests.Then judge peak value according to threshold value, and the sequence number of peak value is recorded in array 4.Module has been used sequential organization body " to remove pseudo-peak ", totally two frames here, and after the program having completed in the first frame, a frame after just can moving.In the first frame, take out adjacent two in array 4 with while loop structure at every turn and count, ask poor rear 11 remainders of removing, remainder is that 0 counter adds 1, otherwise directly enters circulation next time.After the each counting of counter, check whether its value has reached C, and C gets 10 here.When stopping circulation after full 10 times of counter meter, deduct 10 × 11=110, " relative position " asked by the value in array 4 now.Need counter O reset afterwards, to carry out computing next time, Here it is arranges the object of the second frame." relative position " adds that " rough position " is exactly synchronous result.
2. channel estimation and equalization algorithm
(1) channel estimation and equalization of ERP-OFDM pattern
ERP-OFDM pattern has been taked the way of frequency domain equalization, and by LS (Least Square) algorithm for estimating, i.e. least square criterion, releases the estimated value of channel, and design on this basis frequency-domain equalizer, adjusts the overall characteristic of channel.
Because transmitting of ERP-OFDM system is a series of OFDM symbol, and in the moment of signal transmitting, the channel that transmits each symbol is almost consistent.Therefore can select a known OFDM symbol of receiver to carry out channel estimating to ERP-OFDM system, then by the symbol of equalizer correction loading section.This known symbol generally uses the long training sequence of preamble field.
If transmit as X, receiving signal is Y, and the impact of wireless channel is corresponding is H, calculates for LS algorithm
require it can make to receive the reception signal after signal and estimation model
square error minimum,
meet
So establish cost function J be
After deriving, have
As shown in figure 15, in program, first intercept two long sequence symbols in synchronization frame, after addition, divided by 2, try to achieve mean value.Because the frame of ERP-OFDM form has done one time IFFT in the time launching, frequency signal has originally been transformed to time domain, and LS algorithm is derived based on frequency domain, so the FFT that will try again converts back frequency domain the signal receiving again.Then according to formula 10, on each subcarrier, do division one time, divided by the long symbol before transmitting, can obtain the channel parameter of estimating.
Try to achieve after the parameter of channel, other OFDM symbols that receive in signal carry out equilibrium according to following formula:
Balanced object is to restore as much as possible the signal before transmitting at receiving terminal, so the signal after equilibrium
be infinitely close to transmitting order X.When programming, remain and on each subcarrier, do division one time, i.e. step-by-step is divided by the impulse response of channel.
(2) channel estimation and equalization of ERP-DSSS/CCK pattern
The person of being different from, ERP-DSSS/CCK pattern is in time domain, to adjust the characteristic of channel, realization equilibrium.By the modeling to wireless channel, can know that multi-path channel can be approximated to be a time-limited FIR filter, the impulse response that solves channel is exactly the coefficient that solves the each tap of filter.
Ask the tap coefficient of filter will use sef-adapting filter, so-called sef-adapting filter refers to: the tap coefficient ω of N rank FIR filter
0ω
1..., ω
n-1can automatically regulate according to the size of evaluated error e (n), make certain cost function minimum.Figure 16 is the schematic diagram of auto-adaptive fir filter.
The present invention arranges cost function according to LMS algorithm, requires the mean square error minimum between output signal and the reference signal of sef-adapting filter.So cost function J is defined as:
J=E{|e (n) |
2}=E{|d (n)-y (n) |
2formula 12
According to steepest descent method, the iterative formula of obtaining the tap coefficient of LMS adaptive algorithm is again
ω (n)=ω (n-1)+2 μ (n) e (n) x (n) formula 13
μ (n) in formula is the constant sequence of controlling evaluated error e (n) convergence rate and filter stability, is called convergence factor.
For the selection of convergence factor, when the present invention has adopted a kind of " first search, rear convergence ", become the thought of convergence factor:
μ in formula
0be a fixing convergence parameter, τ represents time search constant.
The LabVIEW program of writing according to above principle can be shown in Figure 17.Programming be 11 rank sef-adapting filters, have two nested loop bodies.Outer circulation is got 11 bit data at every turn and is sent into filter, and interior circulation is for calculating the output y (n) of each iteration postfilter.Deduct output valve by reference signal and be evaluated error, be recorded in array " error ", and can watch by oscilloscope the convergence situation of error.The whole zero setting of coefficient of filter when initial, is realized and being upgraded by the relevant parameter of stack when each iteration, and numerical value is kept in shift register, for circulation time next time.Here the convergence factor parameter μ choosing
0=0.1, time search constant τ is 20.
In addition, LabVIEW provides the driver of various modular instruments, by cooperatively interacting of multiple driver, and the correct setting of instrument parameter, just can manipulate controller and call radio-frequency module work.The general flow figure of modular instrument work as shown in figure 18.Equally, the configuration of software also should be followed this principle.
1. transmitter driver
As shown in figure 19, table 6 is explanations of the driver module to using in program, and mainly the input parameter to each VI and the function of realization are described.
Module in table 6 transmitter driver
Associative list 6 and Figure 19 can find out, driver module is interconnective by instrument handle (instrument han dle), comprising the input parameter of all VI above in handle.Instrument operating procedure is as follows:
(1) first program is used " niRFSA Initialize " VI initialization instrument." resource name " refers to the instrument title that needs startup, and the input is here the logical resource name of PXIe-5673E, i.e. " RFSG ";
(2) configure instrument parameter then.Set required centre frequency, transmitting power and the I/Q speed of radiofrequency signal by three parameter configuration module, and generate required initial phase, sampling interval and the baseband complex signal etc. of analog waveform.The radiofrequency signal of 802.11g system works in the ISM band of 2.4GHz, retains the licensed band of exempting from using to industry (Industrial), scientific research (Scientific) or Medical Devices (Medical).Concrete channel distribution and the visible table 7 of centre frequency of each channel.
The channel plan of table 7 2.4GHz frequency band
(3) then data are write in instrument.Need to load and start I/Q modulation module (niRFSG Configure IQ Enabled), resampling module (rfsg_Resample and Write) and electromagnetic wave transmitting (niRFSG Initiate) and stop module (niRFSG Abort), make the electromagnetic wave can repeat its transmission by a loop structure body here, certainly, this is for same Frame;
(4) finally need to close instrument (niRFSG close), or in the time of data exception, show run-time error.
2. receiver driver
The hardware module of receiver, because want the work such as settling signal reception, data sampling, frequency spectrum demonstration, so driver slightly complicated is mainly reflected in the configuration of parameter, is shown in Figure 20.Table 8 is functional descriptions of driver module in program.
The workflow of receiver hardware is as follows:
(1) instrument initialization.Receiving unit uses " niRFSA Initial " to start instrument, corresponding, the logical resource name " RFSA " that its " resource name " should be PXIe-5663, and generate handle with this;
(2) configure instrument parameter.The parameter in this stage is mainly divided into three parts, is respectively the trigger parameter of signal reception, sampling parameter and the desired parameter of demonstration frequency spectrum of A/D conversion.
1) trigger parameter that signal receives
First be the receive mode of instrument, PXIe-5663 provides two kinds of receive modes, is respectively IQ and Spectrum.If will carry out to the received signal demodulation analysis, need instrument to be set as the former; If will carry out to the received signal power spectrumanalysis, need instrument to be set as Spectrum mode.Native system mainly carries out Base-Band Processing to the received signal, thereby should be IQ by this setting parameter; Then be maximum power and the centre frequency of expecting to receive signal.Centre frequency need to be identical with arranging of transmitter, and by " IQ carrier Frequency ", input frame is inputted in the interface of receiver, and maximum power is that reserved parameter is set as-45dB here in order to ensure to receive the integrality of signal; Finally need to select to trigger the type of subsystem, this parameter can be divided into again digital edge-triggered subsystem, software and trigger three kinds of subsystem and power trigger subsystems, here adopted power trigger subsystem pattern, determine according to power trigger levels when instrument starts to receive signal sampling, minimum noise samples point is stored in the memory space of instrument guaranteeing, thereby has saved valuable internal memory.In the time that the performance number of reception signal starts to rise and arrives trigger value, triggering system work.
2) sampling parameter of A/D conversion
Comprise sample frequency and sampling number etc. to received signal.The IQ speed of ERP-OFDM signal is 20Mbps, ERP-DSSS/CCK signal be 11Mbps, according to nyquist sampling law, sample rate at least should be the twice of speed, so here according to the system pattern that do not pass through, corresponding sample rate is set respectively; Sampling number represents the number of the sampled point that instrument provides altogether, and this wherein also comprises the data of noise signal naturally.Which kind of frame format due to no matter, the maximum of its PSDU part can not exceed 4095 eight hytes, so as long as ensure that sampling number is greater than 40000.In addition, also have a reference clock to choose, this parameter has four kinds of selections: Onboard clock, and RedIn, ClkIn and PXI_Clk, these different selections are corresponding to the connection method of different tri-sub-module input mouths of composition PXIe-5663.This is set as PXI_Clk by native system.
3) show frequency spectrum desired parameters
In order to observe the spectrogram that receives signal on receiver, need to use following parameter: carrier frequency, demonstration bandwidth, spectrum mode and resolution bandwidth.Carrier frequency with above mention identical, set according to table 5.2; Show that bandwidth refers to the spectrum width presenting on receiver, if arrange little, frequency spectrum show imperfect, otherwise signal spectrum relative narrower cannot be carried out observation and analysis to it.Here according to the bandwidth of ERP-OFDM signal be 20MHz, ERP-DSSS/CCK signal be 22MHz and be set as 40MHz; Average mode has been chosen RMS (root mean square) pattern, i.e. signal effective value representation; Resolution bandwidth is an important parameter of spectrum analyzer, can identify the minimum frequency space of two signals in order to characterize instrument, if the sigtnal interval is less than the value of resolution bandwidth, instrument cannot distinguish.So to two tight two adjacent signals, its resolving power depends on the resolution bandwidth of spectrum analyzer.Here be set to 150kHz.
4) Transfer Parameters
Calling " niRFSA commit " writes above-mentioned parameter in the internal memory of PXIe-5663.
(3) data read and module loading.Contrary with transmitting terminal, the hardware module of receiver need to read out the I/Q data in instrument, to carry out follow-up operation, as samples and consigns to band receiver of base and carry out the processing such as synchronous, balanced, finally obtains initial PSDU information.Meanwhile, signal, after frequency domain is processed, can also be observed its spectrogram at receiving terminal, uses the reason of loop structure the same with transmitter here, is in order to observe repeatedly waveform.Specifically inform that by " niRFSA Initate " VI instrument parameter has configured, can start to receive data; By " niRFSA Fetch IQ " module, the data that are stored on PXIe-5663 internal memory after sampling are transferred in the internal memory of controller, timeout parameter value is wherein set as-1, represents that this operation will be waited for always until trigger event produces; Re-use " niRFSA Abort " VI and stop the initialized I/Q data read operation by " niRFSA Initate ".
(4) finally merge the error message of band receiver of base and driver, close instrument by " niRFSA close " VI.
The module of table 8 receiver driver
By reference to the accompanying drawings embodiments of the present invention are explained in detail above, but the present invention is not limited to above-mentioned execution mode, in the ken possessing those of ordinary skill in the art, can also under the prerequisite that does not depart from aim of the present invention, makes a variety of changes.
Claims (7)
1. a method of testing for Wireless LAN Equipments test platform, is characterized in that, Wireless LAN Equipments test platform comprises Wireless LAN testing emission system and Wireless LAN testing receiving system; Described Wireless LAN testing emission system comprises radio frequency sending set test module and the hardware processing module that transmits, radio frequency sending set test module converts data to be transmitted, form baseband complex signal, the hardware processing module of transferring to transmit is processed and is generated radio magnetic wave, and launches by antenna; Described Wireless LAN testing receiving system comprises radio-frequency transmitter test module and receives signal hardware processing module, receive signal hardware processing module by antenna reception radio magnetic wave, and process and obtain receiving sequence, pass to again radio-frequency transmitter test module and carry out corresponding inverse transformation, restore information; Method of testing comprises the steps:
Steps A. generate a group data stream and simulate the frame of MAC layer by PN sequence generator, as armed information, and the working frequency range of selected data transmission rate and radiofrequency signal;
Data flow described in Wireless LAN Equipments transmitting to be measured receiving step A for step B., calculates bit information error rate;
Data flow described in described Wireless LAN Equipments test platform transmitting receiving step A for step C., calculate equally bit information error rate, and record radio frequency parameter in radio-frequency transmitter test module and frame synchronization starting point, time domain waveform figure, planisphere, the spectrogram data of received signal;
Data flow described in described Wireless LAN testing emission system step of transmitting A for step D., and with Wireless LAN Equipments reception signal to be measured, observe the variation of bit information error rate;
Step e. by data flow described in Wireless LAN Equipments step of transmitting A to be measured, and with Wireless LAN testing receiving system receive signal, observe bit information error rate, and record radio frequency parameter in radio-frequency transmitter test module and frame synchronization starting point, time domain waveform figure, planisphere, the spectrogram data of received signal;
Step F. finally related data is compared, according to the quality of protocol of wireless local area network design code evaluation Wireless LAN Equipments to be measured, obtain data results, wherein, related data comprises bit information error rate, radio frequency parameter, frame synchronization moment position, time domain waveform figure, spectrogram and planisphere.
2. method of testing according to claim 1, is characterized in that: described radio frequency parameter comprises low-converter gain, outside gain, frequency mixer level, intermediate frequency power output, rf attenuation and intermediate frequency decay.
3. method of testing according to claim 1, is characterized in that: described data results comprises frame synchronization moment position, bit information error rate, time domain waveform figure, spectrogram, planisphere and error message.
4. method of testing according to claim 1, is characterized in that: in described method of testing, transmitting-receiving data flow is ERP-OFDM pattern; Wherein said Wireless LAN Equipments test platform data streams comprises: first successively the frame of MAC layer is carried out framing, scrambling, convolutional encoding, interweaved and mapping, inverse fast Fourier transform and interpolation protection interval by radio frequency sending set test module, then by transmit hardware processing module to signal arrange the modulation of waveform, IQ road, high power amplifies, and sends by antenna; Described Wireless LAN Equipments test platform receiving data stream comprises: receive signal hardware processing module by antenna reception radio magnetic wave; and radio magnetic wave is carried out to linear prower amplifier HeIQ road successively and detects, then by radio-frequency transmitter test module successively to signal carry out synchronously, channel estimating, equilibrium, deletion protect that interval, fast Fourier transform, inverse mapping deinterleave, decoding, descrambling and parse for frame.
5. method of testing according to claim 4, is characterized in that: under described ERP-OFDM pattern, in transmitting data flow step, also comprise the pilot sub-carrier operation between map operation and inverse fast Fourier transform operation.
6. method of testing according to claim 4, is characterized in that: described interpolation protection is spaced apart the data Replica of 16 bits after each OFDM symbol to before this symbol, forms prefix, at the unremitting Nature Link in interface point place; Described deletion protection is spaced apart the data of initial 16 bits of removing each OFDM symbol.
7. method of testing according to claim 1, it is characterized in that: in described method of testing, transmitting-receiving data flow is ERP-DSSS/CCK pattern, wherein said Wireless LAN Equipments test platform data streams comprises: first successively the frame of MAC layer is carried out to framing, scrambling, coding and spread spectrum by radio frequency sending set test module, then by transmit hardware processing module to signal carry out the modulation of IQ road, high power amplifies, and send by antenna; Described Wireless LAN Equipments test platform receiving data stream comprises: receive signal hardware processing module by antenna reception radio magnetic wave, and radio magnetic wave is carried out to linear prower amplifier HeIQ road successively and detects, then by radio-frequency transmitter test module successively to signal carry out synchronously, channel estimating, equilibrium, despreading, decoding, descrambling and parse for frame.
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| CN104618299B (en) * | 2015-02-15 | 2017-11-03 | 东南大学 | A kind of channel estimation methods tested towards IEEE 802.11ac RF consistencies |
| US9825717B2 (en) * | 2015-07-08 | 2017-11-21 | Litepoint Corporation | Method for testing a radio frequency (RF) data packet signal transceiver using implicit synchronization |
| CN108292968B (en) * | 2015-11-30 | 2022-03-15 | 索尼集团公司 | Method for efficient channel access, mobile communication system and mobile communication device |
| US9942074B1 (en) | 2016-11-30 | 2018-04-10 | Micron Technology, Inc. | Wireless devices and systems including examples of mixing coefficient data specific to a processing mode selection |
| US10027523B2 (en) | 2016-11-30 | 2018-07-17 | Micron Technology, Inc. | Wireless devices and systems including examples of mixing input data with coefficient data |
| CN108964808B (en) * | 2017-05-23 | 2021-10-26 | 广东顺德中山大学卡内基梅隆大学国际联合研究院 | Radio frequency transceiver chip test system for wireless local area network |
| CN111193557B (en) * | 2018-11-14 | 2023-09-19 | 广东新岸线科技有限公司 | Calibration tester for ultra-high-speed wireless local area network |
| US10886998B2 (en) | 2019-02-22 | 2021-01-05 | Micron Technology, Inc. | Mixing coefficient data specific to a processing mode selection using layers of multiplication/accumulation units for wireless communication |
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| CN101674142A (en) * | 2009-09-24 | 2010-03-17 | 苏州博联科技有限公司 | Production test system of large-scale short-distance wireless data transmission equipment |
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