Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L27/00—Modulated-carrier systems
  • H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
  • H04L27/22—Demodulator circuits; Receiver circuits
  • H04L27/227—Demodulator circuits; Receiver circuits using coherent demodulation
• • 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
  • H04B1/69—Spread spectrum techniques
  • H04B1/707—Spread spectrum techniques using direct sequence modulation
  • H04B1/7097—Interference-related aspects
  • H04B1/711—Interference-related aspects the interference being multi-path interference
  • H04B1/7113—Determination of path profile
• • 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
  • H04B1/69—Spread spectrum techniques
  • H04B1/707—Spread spectrum techniques using direct sequence modulation
  • H04B1/709—Correlator structure
  • H04B1/7093—Matched filter type

Definitions

• the present invention relates to signal detection of wireless mobile communication, and more particularly, to a multi-selective coherent detection method and device.
• the received signal will be affected by the so-called Doppler effect, and a Doppler frequency shift will be generated relative to the transmitted signal.
• the magnitude and characteristics of this frequency shift are caused by the relative movement of the transmitter and receiver, and the signal.
• the transmission environment is determined.
• the phase of the received wireless communication transmission signal will appear as a phase rotation or even flipping. Therefore, the influence of these factors must be fully considered when detecting the signal.
• a (k) is after passing the letter
• the attenuation factor, ⁇ (1 is the phase rotation angle of the signal after it passes through the channel.
• N (k) is the additive noise.
• K is the index number of the discrete signal, and the data and signal samples are transmitted at a constant rate. The same time can also be used as the index number of the time.
• the total number of samples of the signal used for signal detection is
• Coherent signal detection method This method directly coherently accumulates signals within the range of L L ⁇ : degrees. That is, the transmitted signal and the received signal are conjugated and multiplied, and the product result is accumulated within the length of L. Finally, the result of the addition of n to the square of the modulus is used as a decision variable for coherent detection.
• n X * (k) is a conjugate complex signal of X (k).
• This detection method can obtain good detection results only when the phase of the received signal does not change much within the length of L, and the phase of the received signal does not change much within the length of L, which is difficult to achieve in some communication environments.
• This difference detection method is the same as method 2 except that the phase of the received signal remains basically unchanged in S diff Can meet its application conditions. However, when the method I also meets the application conditions (the phase of the received signal remains basically unchanged within the L length), the detection performance loss of the differential detection method is also smaller than the gain brought by the suppression of phase rotation. The detection performance is worse than the coherent detection method of method 1.
• a joint detection method This method is a combination of the above three methods.
• the size range of the Doppler frequency shift is detected (or limited) by a certain method.
• non-coherent or differential Detection method under low Doppler frequency shift, coherent detection method is used. This method is difficult to implement, and it does not provide the best detection performance.
• Method 1 is based on the assumption that the signal phase is basically unchanged within the L length range. At low frequency offsets (including Doppler frequency shift and system frequency offset, the same applies hereinafter), this condition can basically be satisfied. (The video chip rate and signal length L are the same below), can achieve a good detection effect, but under large frequency deviation, this assumption may not hold, within the length of L, the signal phase may change greatly or even occur Phase inversion, which may cause the coherent results to cancel each other out, so that the detection performance drops sharply, so that no signal can be detected.
• method 1 can also satisfy the condition that the phase is basically unchanged within the coherence length L. At this time, the non-coherent phase of method 2 has a certain performance compared to method 1. loss.
• Method 4 can get better performance under various Doppler frequency shifts.
• the method defined by the protocol brings complexity.
• the detection method requires a Doppler frequency shift estimation module, and the accuracy is difficult to guarantee. Summary of the invention
• the purpose of the present invention is to solve the problems in the above-mentioned detection methods, and propose a multi-selection coherent detection method and device to reduce the influence of phase rotation caused by frequency offset and increase the probability of signal detection.
• the multi-selective coherent detection-test method of the present invention includes the following steps:
• the multi-selection coherent detection device used in the present invention includes:
• a matched filter unit two or more branch units, and a branch selection unit.
• the input signal is input to the matched filter unit for matched filtering, and the output of the matched filter unit is sent to each branch unit, each branch unit.
• the signals are phase-adjusted and phase-accumulated, respectively, and sent to the branch selection unit, and the branch selection unit performs branch output selecting the largest mode.
• FIG. 1 is a principle block diagram of a wideband code division multiple access (WCDMA) reverse access receiving system using the method of the present invention
• WCDMA wideband code division multiple access
• Figure 3 shows a comparison of the performance of a wideband code division multiple access (WCDMA) reverse access prefix detection method.
• WCDMA wideband code division multiple access
• OPT ⁇ Z, ⁇ , t 0 ... C- ⁇ (12)
• OPT ⁇ is the selection of the optimal operator, which means that the optimal value is selected from a series of values.
• the above segments are generally equally spaced segments, but depending on the situation, they may also be unevenly spaced segments.
• phase rotation ⁇ P-1 phase rotation, where ⁇ can be any value.
• the relationship between phase rotation ⁇ and ⁇ is not limited to this expression.
• step a a coherent result X; is obtained for each segment, with a total of N mullie . h , and perform P phase adjustments on each coherent result according to step b.
• step e the optimal principle can be selected using the maximum modulus method.
• WCDMA Wideband Code Division Multiple Access
• the prefix chip length is 4096chip, at a chip rate of 3.84Mbp / s and a carrier frequency of 2GHz, and At the speed of 500Km / h required by the WCDMA protocol standard, signal phase inversion may occur completely within the range of 4096chip chips. If the aforementioned method 1 is adopted under these conditions, the performance will inevitably be reduced sharply (see curve 1 in Figure 3).
• FIG. 1 is specifically applied to the system shown in FIG. 1 as a method of the present invention.
• a received signal passes through an antenna 40 to a band-pass filter 41 for a wideband code division multiple access (WCDMA) frequency band.
• WCDMA wideband code division multiple access
• the baseband portion 42 completes the conversion of the radio frequency signal to the baseband signal and the functions of digital-to-analog conversion to obtain a baseband signal.
• the baseband signal is sent to a multi-selection coherent circuit 43 to obtain a multi-selection coherent signal.
• Multiple choice coherence The signal is sent to the multipath extraction circuit 44 for multipath extraction, and the obtained multipath information is sent to the despreading and RAKE summing circuit 45 as its first input port signal.
• the baseband signal is directly sent to the despreading and RAKE summing circuit 45 as its second input port signal.
• the despreading and RAKE summation circuit 45 performs despreading and RAKE summation on the baseband signal according to the multipath information sent from the multipath extraction circuit 44, and outputs the result after the summation.
• the multi-selection coherent detection device includes a matched filter unit, two or more branch units, and a branch selection unit.
• An input signal is input to the matched filter unit for matched filtering.
• the output is sent to each branch unit, and each branch unit performs phase adjustment and coherent accumulation on the signal and sends it to the branch selection unit.
• the branch selection unit performs the branch output that selects the largest mode.
• Each of the branch units further includes a multiplier for phase adjustment, an adder for coherent accumulation, a holder for holding data, and a delay for data delay.
• the output of the matched filtering unit is sequentially multiplied.
• the adder and adder are sent to the branch selection unit: At the same time, the adjustment series is sent to the multiplier after the retainer, and the delayer also feeds back the output of the adder to the input of the adder.
• the input signal is output through the matched filter 1, it is divided into 8 branches and sent to the multipliers 2 to 9 as their first input port signals.
• the 8 branches are identical except for the input signals of the holders 10-17.
• branch 1 includes a multiplier 2, a keeper 10, an adder 18, and a delay 26.
• the four-digit adjustment series 1, 1, and 1 are input to the holder 10, and the holder 10 holds the 1024 chip time for each adjustment series information bit, that is, the first digit of the adjustment series is output at the first 1024 chip time Information, and then the second bit of the adjustment series is output at the second 1024 chip time, the third bit of the adjustment series is output at the 1024 chip time, and the fourth 1024 chip time is output at the 4th series Bit of information.
• the output of the holder 10 is used as a second input port signal of the multiplier 2.
• the multiplier 2 can complete the 0 'or 180' phase adjustment of the output signal of the matched filter 1, and the phase-adjusted signal is sent to the adder 18 as its first input port signal, and the other input port of the adder 18 Connected to the delayer 26, the adder sums the first input port and the second input port, and then outputs to the selector 33 and the delayer 26.
• the delayer delays the signal sent from the adder 18 by a 1024 chip time, and feeds it back to the second input port of the adder 18.
• the adjustment series of input holder 11 is 1, 1, 1,-1
• the adjustment series of input holder 12 is 1, 1,-1, 1, 1
• the adjustment series of input holder 13 is 1, 1,-1, 1. -1
• the adjustment series of the input holder 17 are I,-1,-1, 1,-1. There are a total of 8 holders, and there are 8 different input adjustment series.
• the summing results of the adders 26 to 32 are sent to the selector 33 as their first to eighth input port information, respectively.
• the coherent result (recorded as 1) is output as the final detection result.
• Channel type Vehicle Class A channel
• the length L used for signal detection is divided into N miiluc .
• coherent accumulation is performed in each segment, and then N multie is performed .
• h coherent results are phase adjusted separately, and a value of an adjustment result is selected for each possible coherent result to make various possible combinations: then these possible combinations are coherently accumulated, and finally the optimal one is selected as the detection result; and according to
• the coherent detection device used in the above method includes a matched filter unit, two or more branch units, and a branch selection unit. The input signal is input to the matched filter unit, and the output of the matched filter unit is sent to each branch. Branch unit, branch selection unit, branch selection unit will select the branch with the largest modulus and output.
• the method and the device of the invention overcome the shortcomings of poor detection performance caused by the system frequency offset, phase rotation, etc., which exist in the above four methods.
• the method and the device suppress the influence of the frequency offset and phase rotation on the signal detection performance in a certain range, and improve the signal detection performance and probability.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
• Radar Systems Or Details Thereof (AREA)

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• 1999
  • 1999-11-25 CN CN99124113A patent/CN1124728C/zh not_active Expired - Lifetime
• 2000
  • 2000-06-12 US US09/830,385 patent/US6907087B1/en not_active Expired - Lifetime
  • 2000-06-12 AU AU52053/00A patent/AU5205300A/en not_active Abandoned
  • 2000-06-12 JP JP2001540549A patent/JP4424882B2/ja not_active Expired - Lifetime
  • 2000-06-12 WO PCT/CN2000/000151 patent/WO2001039530A1/zh not_active Ceased
  • 2000-06-12 KR KR1020017005671A patent/KR100659440B1/ko not_active Expired - Lifetime

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