CN100571052C - The receiver that is used for a CDMA communication system - Google Patents
The receiver that is used for a CDMA communication system Download PDFInfo
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- CN100571052C CN100571052C CNB2006100067257A CN200610006725A CN100571052C CN 100571052 C CN100571052 C CN 100571052C CN B2006100067257 A CNB2006100067257 A CN B2006100067257A CN 200610006725 A CN200610006725 A CN 200610006725A CN 100571052 C CN100571052 C CN 100571052C
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Abstract
The receiver that is used for a CDMA communication system includes a signal receiving terminal; One data output unit is used for the signal that received according to this signal receiving terminal, exports a plurality of data sequences; One control unit is used for a plurality of data sequence numbers in the output of this data output unit during less than one first value, exports the data sequence of maximum signal strength in these a plurality of data sequences; One first multiplication unit is used for the signal that this signal receiving terminal is received be multiply by the data sequence that this control unit is exported; One high pass filter unit is with the direct current component that removes the signal that this first multiplication unit exports; And one second multiplication unit, be used for the data sequence that this control unit is exported be multiply by the signal that this high pass filter unit is exported.
Description
Technical field
The present invention relates to a kind of receiver that is used for a CDMA communication system, particularly relate to a kind of receiver of strengthening the signal receiving efficiency.
Background technology
In wireless telecommunication system, code division multiple access (Code Division Multiple Access) technology is a kind of exhibition communication (Spread-Spectrum) frequently technology, that its major advantage is is anti-interference, multipath suppresses (Multipath Rejection), and multitask access etc., except that strengthening the signal reliability and promoting the confidentiality, also can make a plurality of independent users share same passage.CDMA (Code Division Multiple Access) is to be based upon on pseudo-random (Pseudo-random) the sign indicating number basis of (or claiming to intend mess code), the frequency spectrum of modulated data is widened, form with similar noise is sneaked in the environment, thereby makes the transmission signal can transmit in channel and can not detected by the earwig.Therefore, CDMA (Code Division Multiple Access) has been widely used in wireless telecommunication system, as: third generation mobile system (3
RdGeneration Mobile Communication System), global positioning system (Global Positioning System) etc.
In the wireless telecommunication system of a code division multiple access, servomechanism installation (transmission ends) can be by different base station signals to client device (receiving terminal).Because the distance of client device and each base station may not be identical, and may be subjected to interference such as landform, atural object, make client device be subjected to the influence of " closely far problem " (Near-Far Problem), cause client device can't lock the more weak signal of power.So-called " nearly problem far away " is meant by different base station and is emitted in the signal of client device that the more weak signal of power is subjected to the interference of the stronger signal of power, causes client device can't lock the more weak signal of power.In the third generation mobile system, ground floor (physical layer) agreement is used the intensity of power control instruction control base station output signal, and the intensity unanimity that each mobile phone signals is received in the place, base station is to overcome " nearly problem far away ".Yet, in global positioning system, be with unidirectional emission (One-way Ranging) broadcast mode by the satellites transmits signal to receiving terminal, so intensity of the uncontrollable satellite signals of receiving terminal, so that receiving terminal can be subjected to the influence of " nearly problem far away ", and cause that receiving terminal can't correctly be located, navigation etc., ask for an interview following explanation.
It is benchmark with the space that global positioning system is one, utilizes a system of radio wave and time difference measuring distance, and it can provide position data, speed and time accurately.The position calculation principle of receiver, broadcast the ranging code (Ranging Codes) that gets off by satellite, measure the launch time of its satellite signals via receiver, again with receiver on time of reception do a comparison, can utilize time difference and transfer rate calculate satellite and receiver between distance.Wherein, ranging code can be divided into two kinds, and one is C/A sign indicating number (Coarse/Acquisition Codes), comparatively rough according to the resulting accuracy of this yard, the special open user who gives general commercial use; Another kind is P sign indicating number (PrecisionCodes), because the minimum length in time of P sign indicating number (claim sheet again, Chip) shorter, can access location more accurately, be generally military use, do not discuss at this.Each satellite all has independent and fixing C/A sign indicating number to recognize that for receiver except the C/A sign indicating number, most important is exactly the satellite data information code.On satellite, this information code can be done convolution (Convolution) with the C/A sign indicating number, is modulated on the carrier wave again.Whether normally the data that this information code comprises have the parts running coefficient etc. of data, ionospheric propagation delay parameter and calculating UTC of launch time, timing alignment data, satellite itself and other satellite of primary track data (Almanac Data), information code of Precise Orbit data (Ephemeris), other satellite of the satellite of this information code of emission itself.
The position calculation principle of receiver is to utilize the triangle positioning principle basically.When receiver is received the signal that a satellite transmits, be converted into the position data at place via inner microprocessor, just can know this satellite from receiver how far and its direction there.When two satellite signals, the position that receiver calculates is two circular scope that spherical signal intersection forms.When the 3rd satellite signals, can be in three spherical signals produce two plotted points, one of them intersection point can arrive earth surface, and the opposite side of satellite in space more then then can be made the longitude and latitude of user position.Further, when receiving four satellite-signals, just can make the longitude and latitude and the height of user position.Therefore, generally speaking, the receiver of existing global positioning system need receive that the satellite signals more than four just can correctly locate.
Because the receiver of existing global positioning system need be received the satellite signals more than four and just can correctly locate, if in the satellite signals that receiver received, the intensity of the intensity of a certain satellite signals above other satellite signals is arranged, will cause receiver to be subjected to the influence of " nearly problem far away ", only lock onto the stronger satellite signals of power, and can't lock the more weak satellite signals of power.For instance, when the user uses vehicle navigation device in the metropolitan area, may be subjected to cloud thickness, windshield, high building and influence such as cover, and be subjected to propagated loss (Propagation Loss), multi-path propagation effect (MultipathPropagation Effect), capture-effect (Shadowing Effect), signal attenuating effect (FadingEffect), signal delay diffusion influences such as (Delay Spread), so that satellite signals intensity is inconsistent, thereby be subjected to the influence of " near far away problem ", can't carry out accurate localization.
Summary of the invention
Therefore, main purpose of the present invention promptly is to provide a kind of receiver that is used for a CDMA communication system.
The present invention discloses a kind of receiver that is used for a CDMA communication system, include a signal receiving terminal, be used for receiving signal; One data output unit is used for the signal that received according to this signal receiving terminal, and output is corresponding to a plurality of data sequences of a plurality of pseudo noise codes; One control unit is used for a plurality of data sequence numbers in the output of this data output unit during less than one first value, exports the data sequence that has maximum relatively signal strength in these a plurality of data sequences; One first multiplication unit is used for the signal that this signal receiving terminal is received be multiply by the data sequence that this control unit is exported; One high pass filter unit is with the direct current component that removes the signal that this first multiplication unit exports; And one second multiplication unit, be used for the data sequence that this control unit is exported be multiply by the signal that this high pass filter unit is exported, and export the result to this signal receiving terminal.
Description of drawings
Fig. 1 is the schematic diagram of an existing code division multiple access system.
Fig. 2 is used for the schematic diagram of the receiver of a CDMA communication system for preferred embodiment of the present invention.
Fig. 3 receives the schematic diagram of the more weak data sequence of the stronger data sequence of a power and a power for the receiver of Fig. 2.
The reference numeral explanation
100 code division multiple access systems
102 pseudo-random code generators
104 local pseudo-random code generators
200 receivers
202 signal receiving terminals
204 data output units
206 control units
208 first multiplication units
210 high pass filter unit
212 second multiplication units
P1, P2 data sequence
Embodiment
The present invention is by in the CDMA communication system, and the characteristic that each pseudo noise code is only relevant with itself reaches the purpose of strengthening the signal receiving efficiency.At first, please refer to Fig. 1, Fig. 1 is the schematic diagram of an existing code division multiple access system 100.For clarity sake, Fig. 1 only draws the relevant signal of pseudo noise code.When transmission ends was desired dateout signal b (t) to receiving terminal, data signals b (t) can multiply each other with the pseudo noise code signal c (t) that a pseudo-random code generator 102 is exported, that is
m(t)＝b(t)×c(t)
According to the fourier transform theorem, the multiply each other frequency spectrum of gained of two signals equals the convolution of two signal spectrum components.Because data signals b (t) be narrow frequency signal, and pseudo noise code signal c (t) is the wideband signal, so both frequency spectrums of modulating (multiplying each other) signal m (t) approximate the frequency spectrum of pseudo noise code signal c (t), and promptly modulating signal m (t) is a wideband signal.Modulating signal m (t) can be subjected to the influence of interchannel noise i (t), makes the reception signal r (t) of receiving terminal be
r(t)＝m(t)+i(t)
＝b(t)×c(t)+i(t)
For demodulation signal r (t), be provided with a local pseudo-random code generator 104 in the receiving terminal, be used for exporting the pseudo noise code signal c (t) identical with pseudo-random code generator 102.The pseudo noise code signal c (t) that local pseudo-random code generator 104 is exported can get signal z (t) after multiplying each other with signal r (t), so
z(t)＝c(t)×r(t)
=c
2(t) * b (t)+c (t) * i (t) (formula 1)
One desirable pseudo noise code signal is only relevant with itself, that is signal is a unit pulse signal (Impulse Signal) on the frequency spectrum axle at oneself the multiply each other signal of gained on the time domain, is constant (as 1) at time shaft.As can be known
c
2(t)=1, to all t
Then (formula 1) can be simplified to
z(t)＝b(t)+c(t)×i(t)
In other words, signal z (t) has comprised the product of simple data signals b (t) and noise i (t) and pseudo noise code signal c (t).Because data signals b (t) is narrow frequency signal, noise i (t) is the wideband signal with the product of pseudo noise code signal c (t), therefore as long as select suitable filter, allows most (c (t) * i (t)) to filter, and just can obtain data signals b (t).
Therefore, as shown in the above description, the pseudo noise code signal is constant from the signal of gained of multiplying each other at time shaft on time domain.The present invention promptly utilizes these characteristics, strengthens the signal receiving efficiency of the receiver of CDMA communication system.Please refer to Fig. 2, Fig. 2 is used for the schematic diagram of the receiver 200 of a CDMA communication system for preferred embodiment of the present invention.For clarity sake, Fig. 2 only draws a signal receiving terminal 202, a data output unit 204, a control unit 206, one first multiplication unit 208, a high pass filter unit 210, and one second multiplication unit 212 of receiver 200.When receiver 200 runnings, earlier by the wireless signal of an antenna (not being plotted among Fig. 2) reception corresponding to different pseudo noise code signals, and wireless signal is converted to digital signal by an analog-to-digital converter (not being plotted among Fig. 2), be sent to signal receiving terminal 202.204 signals that received according to signal receiving terminal 202 of data output unit are exported a plurality of data sequences corresponding to a plurality of pseudo noise codes, and export the result to control unit 206.Control unit 206 can during less than a particular value, be exported data sequence to the first multiplication unit 208 that has maximum relatively signal strength in these a plurality of data sequences in a plurality of data sequence numbers of data output unit 204 output.In addition, control unit 206 also can export a plurality of data sequences of data output unit 204 outputs to a signal processing unit (not being plotted among Fig. 2), handles to carry out signal.First multiplication unit 208 is used for the signal that signal receiving terminal 202 is received be multiply by the data sequence that control unit 206 is exported, and export the result to high pass filter unit 210, to remove the direct current component of the signal that first multiplication unit 208 exported by high pass filter unit 210.Then, second multiplication unit 212 multiply by the signal of control unit 206 outputs with the signal of high pass filter unit 210 outputs, and exports the result to the signal receiving terminal.That is to say that if the data sequence number of data output unit 204 output is during less than a particular value, the data sequence that has maximum relatively signal strength in the data sequence that control unit 206 can be exported data output unit 204 is sent to first multiplication unit 208.By first multiplication unit 208 signal that signal receiving terminal 202 is received be multiply by the data sequence that control unit 206 is exported, the data sequence that multiply each other certainly signal and the power of the data sequence that available power is stronger is stronger and the signal that multiplies each other of other data sequence.The signal of gained is a constant at time shaft because the pseudo noise code signal multiplies each other on time domain certainly, therefore after the processing via high pass filter unit 210, the part of constant can be filtered (constant is a baseband signal).After the signal of high pass filter unit 210 output multiplies each other with the stronger data sequence of power again, the part of data sequence that can power is stronger is eliminated, and obtain the signal of the stronger data sequence of inactivity, solve the more weak data sequence of power for the data output unit.
For instance, please refer to Fig. 3, suppose that the data sequence that the signal receiving terminal is received is P1 and P2, wherein the power of data sequence P1 is strong than the power of data sequence P2.Therefore, data output unit 204 can solve data sequence P1.If required data sequence number is 2, then control unit 206 can be sent to first multiplication unit 208 with data sequence P1.Therefore, the output signal of first multiplication unit 208 is (P1 * P1+P1 * P2).Because P1 * P1 equals constant, so the output signal of high pass filter unit 210 is (P1 * P2).In like manner, the signal that exports signal receiving terminal 202 to of second multiplication unit 212 is P2.Thus, data output unit 204 can solve the more weak data sequence P2 of power and not be subjected to the influence of data sequence P1.
As previously mentioned, in global positioning system, each satellite can be done convolution with the C/A sign indicating number with information code and be modulated on the carrier wave, and every satellite all has independently C/A sign indicating number.When starting satellite fix, four satellite signals of the minimum needs of receiver.If when relatively strong, can make receiver be subjected to the influence of nearly problem far away, and can't solve the signal of other satellite output from the signal power of a certain satellite.By the present invention, receiver 200 demodulates power stronger satellite signals (being P1 shown in Figure 3) relatively earlier, pass through first multiplication unit 208, high pass filter unit 210 again, reach the influence removal of second multiplication unit 212 satellite signals that power is stronger, thereby demodulate more weak satellite signals (being P2 shown in Figure 3).Thus, when the user uses vehicle navigation device in the metropolitan area, be subjected to cloud thickness, windshield, high building and influence such as cover, so that when satellite signals intensity is inconsistent, receiver 200 of the present invention can overcome the influence of nearly problem far away, and demodulate the more weak satellite signals of power, and then accurately finish runnings such as location, navigation.
The above only is preferred embodiment of the present invention, and all equalizations of doing according to claim of the present invention change and modify, and all should belong to covering scope of the present invention.
Claims (7)
1. receiver that is used for a CDMA communication system includes:
One signal receiving terminal is used for receiving signal;
One data output unit is used for the signal that received according to this signal receiving terminal, and output is corresponding to a plurality of data sequences of a plurality of pseudo noise codes;
One control unit is used for a plurality of data sequence numbers in the output of this data output unit during less than one first value, exports the data sequence that has maximum relatively signal strength in these a plurality of data sequences;
One first multiplication unit is used for the signal that this signal receiving terminal is received be multiply by the data sequence that this control unit is exported;
One high pass filter unit is with the direct current component that removes the signal that this first multiplication unit exports; And
One second multiplication unit is used for the data sequence that this control unit is exported be multiply by the signal that this high pass filter unit is exported, and exports the result to this signal receiving terminal.
2. receiver as claimed in claim 1, wherein this data output unit is used for the correlation of the signal exported according to this signal receiving terminal and this a plurality of pseudo noise codes, exports a plurality of data sequences corresponding to these a plurality of pseudo noise codes.
3. receiver as claimed in claim 1, wherein this control unit was used for a plurality of data sequence numbers in the output of this data output unit less than 4 o'clock, exported the data sequence that has maximum relatively signal strength in these a plurality of data sequences.
4. receiver as claimed in claim 1, wherein this control unit also is used for exporting a plurality of data sequences of this data output unit output to a signal processing unit, handles to carry out signal.
5. receiver as claimed in claim 1, it also comprises:
One antenna is used for receiving wireless signal; And
One analog-to-digital converter is electrically connected in this antenna and this signal receiving terminal, after the wireless signal that is used for that this antenna is received is converted to digital signal, is sent to this signal receiving terminal.
6. receiver as claimed in claim 1, wherein this CDMA communication system is a third generation mobile system.
7. receiver as claimed in claim 1, wherein this CDMA communication system is a global positioning system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006100067257A CN100571052C (en) | 2006-02-07 | 2006-02-07 | The receiver that is used for a CDMA communication system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006100067257A CN100571052C (en) | 2006-02-07 | 2006-02-07 | The receiver that is used for a CDMA communication system |
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| Publication Number | Publication Date |
|---|---|
| CN101018072A CN101018072A (en) | 2007-08-15 |
| CN100571052C true CN100571052C (en) | 2009-12-16 |
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|---|---|---|---|
| CNB2006100067257A Expired - Fee Related CN100571052C (en) | 2006-02-07 | 2006-02-07 | The receiver that is used for a CDMA communication system |
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| Country | Link |
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