JP4032584B2 - Spread spectrum demodulator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for demodulating a received spread spectrum signal, for example, provided in a spread spectrum receiver applied to a mobile station and a base station of a mobile communication system.
[0002]
[Prior art]
At present, application of spread spectrum communication to mobile communication is being actively studied. Above all, CDMA (Code Division Multiple Access), which is a multiple access method using a direct spreading method, is considered to be advantageous from the viewpoints of flexibility of service that can be supplied, effective use of frequency bands, and the like. Therefore, CDMA is standardized as one of the access methods of the third generation mobile communication system.
[0003]
In direct spread spectrum spread communication, a spread spectrum signal is created and transmitted using a spread code that is independent of the information signal to be transmitted and has a wider bandwidth than the information signal. When demodulating the spread spectrum signal, the same reference code as the spread code on the transmission side is used, and the spread spectrum signal is despread using this reference code.
[0004]
The spread spectrum signal despreading process is roughly divided into so-called active correlation processing and passive correlation processing. The active correlation process multiplies the received spread spectrum signal while shifting the reference code in time, and integrates the multiplication result over one period of the reference code to obtain a correlation value. On the other hand, the passive correlation process uses a matched filter, and obtains a correlation value by multiplying the matched filter by a tap coefficient corresponding to a spread code set in advance and a spread spectrum signal. A passive correlator typified by a matched filter generally has a more complicated structure than an active correlation element, and has a large scale. Therefore, an active correlator is generally used when configuring a spread spectrum receiver at low cost.
[0005]
FIG. 14 is a block diagram showing a configuration of a conventional spread spectrum demodulator to which an active correlator is applied. An analog baseband signal corresponding to the received spread spectrum signal is converted into a digital baseband signal by an A / D (Analog / Digital) conversion unit (not shown), and then supplied to the despreading unit 90. The despreading unit 90 performs active correlation processing based on the reference code generated by the reference code generation unit 91 to restore a symbol signal including the original symbol from the spread spectrum signal.
[0006]
The active correlation processing will be described in more detail. The active correlation processing is repeatedly performed for each symbol which is one unit after narrowband modulation. That is, assuming that a certain unit time is one slot, the active correlation process performs a multiplication process of a received signal and a reference code and an integration process of the result every time obtained by dividing one slot by the number of symbols included in one slot. Repeatedly. Thus, the original information is restored for each symbol.
[0007]
The symbol signal restored by despreading section 90 is provided to pilot synchronous detection section 92. The pilot synchronous detection unit 92 performs synchronous detection of the symbol signal based on the pilot symbol included in the symbol signal. That is, pilot synchronous detection section 92 extracts pilot symbols included in the symbol signal in pilot symbol selection section 93 and channel estimation section 94 obtains a reference phase. The pilot synchronous detector 92 delays the symbol signal by the processing delay unit 95 and then detects the symbol signal by the complex multiplier 96 based on the reference phase. Thus, the original information is restored.
[0008]
By the way, in the third generation mobile communication system, in order to provide information services and applications of various transmission rates to users, a plurality of spreading factors (SF) are selectively used as necessary. The bit rate can be changed. This is disclosed, for example, in the 3GPP (3rd Generation Partnership Project) standardization standard "TS25.211 Ver.3.0.0 (1997-0), p9 or p17", which is the standardization mechanism for third generation mobile communications. Yes.
[0009]
More specifically, in the technique disclosed in this standard, a plurality of spreading factors are set as power values of 2. The spreading factor represents how many chips of one cycle of spreading code are used to spread one symbol, and corresponds to a value obtained by dividing the chip rate by the symbol rate. On the other hand, since the chip rate determines the transmission bandwidth, it is difficult to change it unnecessarily. Therefore, if the chip rate is kept constant and the spreading factor is changed, the symbol rate changes. As a result, the bit rate changes.
[0010]
For example, if the spreading factor is set to a relatively small value, the number of symbols spread with one cycle of spreading code becomes relatively large. Therefore, the symbol rate is relatively high, and as a result, the bit rate is also high. On the contrary, if the spreading factor is set to a relatively large value, the number of symbols spread by one cycle of spreading code becomes relatively small. Therefore, the symbol rate is lowered, and as a result, the bit rate is also lowered.
[0011]
For this reason, for example, a reference code having a large spreading factor is usually assigned, and when a high-speed information service is required, a reference code having a low spreading factor can be assigned according to the demand. By doing so, it is possible to improve the service to the users while securing the number of users.
[0012]
[Problems to be solved by the invention]
As described above, it is desirable to use an active correlator as a despreader in order to manufacture a spread spectrum receiver at a low cost. Therefore, in order to manufacture a spread spectrum demodulator at low cost and improve service to users, it is conceivable to apply the technology disclosed in the above standard to a spread spectrum demodulator using an active correlator. . However, in this case, since the technique disclosed in the above-mentioned standard uses a plurality of spreading factors, there is a problem that the manufacturing period of the spread spectrum demodulator becomes longer or the manufacturing process becomes complicated.
[0013]
More specifically, as described above, if the spreading factor is changed, the symbol rate changes. On the other hand, since active correlation processing is performed every time obtained by dividing one slot by the number of symbols included in one slot, if the symbol rate changes, the execution cycle of active correlation processing must also be changed. For example, when the spreading factor is 16, multiplication processing and integration processing are repeatedly executed in one slot at a time interval of 16 chips, whereas when the spreading factor is 256, multiplication processing is performed at a time interval of 256 chips. Etc. must be repeatedly executed in one slot.
[0014]
Therefore, the interval at which the despreading process is executed, that is, the output timing of the pulse and the control signal, etc. must be made dependent on the spreading factor. Therefore, for example, if eight types of spreading factors are set, design and operation verification of operation timings of the despreading unit 90, pilot symbol selection unit 93, channel estimation unit 94, processing delay unit 95, complex multiplication unit 96, etc. are performed. Must be done for each type of spreading factor. Therefore, the manufacturing time is prolonged and the manufacturing process is complicated.
[0015]
Accordingly, an object of the present invention is to solve the above-described technical problem, apply the active correlation process as a despreading process, and to reduce the manufacturing time when a plurality of spreading factors can be changed. A demodulator is provided.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a spread spectrum demodulating spread spectrum signal including a pilot symbol and a data symbol, which is created based on a spreading code of any one of a plurality of preset spreading factors. A demodulator, Provided in each of a plurality of finger parts, By performing active correlation processing on the spread spectrum signal based on a reference code of a partial spreading factor having a length equal to or shorter than the shortest spreading factor among the plurality of spreading factors, a symbol of 1 symbol or less A partial despreading unit for obtaining a partial symbol signal consisting of partial symbols of length; A data selector for time division multiplexing and outputting the partial symbol signals output from each finger unit, and a partial symbol signal corresponding to each finger unit output from the data selector unit for synchronous detection in a time division manner. Common to each finger part Pilot synchronous detector and after synchronous detection by this pilot synchronous detector Corresponding to each finger Partial symbol signal Each time-sharing By integrating Corresponding to each finger Data symbol Respectively A symbolic integrator to restore A RAKE combining unit that performs RAKE combining of data symbols corresponding to each finger unit restored by the symbolizing integration unit; Is included.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0018]
Embodiment 1
FIG. 1 is a conceptual diagram showing a configuration of a mobile communication system to which a spread spectrum demodulator according to Embodiment 1 of the present invention is applied. This mobile communication system applies a so-called third generation mobile communication system, and applies CDMA as a communication access system. More specifically, this mobile communication system has a base station 1 and a mobile station 2 and achieves mobile communication by wirelessly communicating a spread spectrum signal between the base station 1 and the mobile station 2.
[0019]
For example, the base station 1 includes a spread spectrum transmitter 3. The spread spectrum transmitter 3 performs narrow-band modulation on communication data to create a symbol signal. Specifically, the spread spectrum transmitter 3 inserts pilot data into the communication data string and modulates the data by, for example, QPSK (Quadrature Phase Shift Keying). Thereby, a symbol signal composed of pilot symbols and data symbols is obtained. The unit length in this case is 1 symbol. The spread spectrum transmitter 3 generates a spread spectrum signal by multiplying the symbol signal by a spread code, and transmits the spread spectrum signal to the mobile station 2.
[0020]
The mobile station 2 includes a spread spectrum receiver 4. The spread spectrum receiver 4 receives the spread spectrum signal transmitted from the spread spectrum transmitter 3 and despreads the spread spectrum signal by active correlation processing to obtain a symbol signal, which is the reverse of the narrowband modulation. A narrowband demodulation process, which is a process, is performed on the symbol signal to obtain the original communication data.
[0021]
The spread spectrum transmitter 3 will be described in more detail. When spreading the symbol signal, the spread spectrum transmitter 3 spreads the symbol signal based on the spread codes having a plurality of spreading factors SF. Here, the spreading factor SF represents the number of chips in which one symbol is spread, and corresponds to a value obtained by dividing the chip rate by the symbol rate. Specifically, the spreading factor SF is a power of 2, that is, 2 ^M (For example, M = 2, 3,..., 8), and takes numerical values such as 4, 8, 16,.
[0022]
In the spread spectrum transmitter 3, the set plurality of spreading factors SF are selectively used in accordance with transmission rates suitable for providing information services and applications. More specifically, when providing a relatively low-speed information service or the like, the spread spectrum transmitter 3 uses the spread signal with a relatively large spreading factor SF to spread the symbol data. As a result, a spread spectrum signal having a relatively low symbol rate, that is, a relatively low bit rate can be obtained. On the other hand, when providing a relatively high-speed information service or the like, the spread spectrum transmitter 3 uses the spread signal with a relatively small spreading factor SF to spread the symbol data. As a result, a spread spectrum signal having a relatively high symbol rate, that is, a relatively high bit rate can be obtained.
[0023]
FIG. 2 is a diagram for explaining a difference in symbol rate due to a difference in spreading factor SF. 2A to 2E show the number of symbols included in one slot when the spreading factor SF is set to 256, 128, 64, 32, and 16, respectively. For example, as shown in FIG. 2A, when the spreading factor SF is 256 and the number of symbols contained in one slot is 10, if the spreading factor SF is changed to 128, which is half of that, FIG. As shown in b), the number of symbols is 20 times that number. When the spreading factor SF is changed to 64, 32, and 16, the numbers of symbols are 40, 80, and 160 as shown in FIGS. 2 (c) to 2 (e), respectively. That is, the symbol rate increases as the spreading factor SF decreases.
[0024]
FIG. 3 is a block diagram showing the internal configuration of the spread spectrum receiver 4. The spread spectrum receiver 4 includes a receiving unit 10. The receiving unit 10 receives a spread spectrum signal transmitted from the spread spectrum transmitter 3 of the base station 1 and gives the spread spectrum signal to the analog signal processing unit 11. The analog signal processing unit 11 creates an analog baseband signal by converting the spread spectrum signal from the carrier band to the baseband band. The analog baseband signal is given to the A / D converter 12. The A / D converter 12 converts the analog baseband signal into a digital baseband signal, and provides the digital baseband signal to the spread spectrum demodulator 13.
[0025]
The spread spectrum demodulator 13 restores the original data symbol by demodulating the digital baseband signal. More specifically, the spread spectrum demodulation unit 13 includes a partial despreading unit 14. The partial despreading unit 14 partially despreads the digital baseband signal by active correlation processing. More specifically, the partial despreading process 14 partially despreads the digital baseband signal every time corresponding to the partial spreading factor PSF using the reference code generated from the reference code generation unit 15. Here, partial despreading is a process of despreading a digital baseband signal with a reference code of a partial spreading factor PSF that is a fixed value. In the first embodiment, the partial spreading factor PSF has a length equal to the shortest spreading factor SF among the plurality of spreading factors SF set in the spread spectrum transmitter 3. ^P (P is a natural number smaller than M). Thereby, a partial symbol signal composed of partial symbols obtained by dividing one symbol at the time of transmission into one or a plurality of symbols is obtained. That is, the partial symbol has a length of one symbol or less. The partial symbol signal is given to pilot synchronous detector 16.
[0026]
The partial despreading unit 14 can be realized by software processing such as hardware or DSP. In this case, there is an effect that it can be applied to a software mobile station corresponding to a plurality of spreading factors SF. .
[0027]
The pilot synchronous detection unit 16 solves the narrow band modulation of the partial symbol signal by performing synchronous detection based on the pilot symbol in the partial symbol signal. More specifically, the pilot synchronous detection unit 16 includes a pilot symbolization integration unit 17, a channel estimation unit 18, a processing delay unit 19, and a complex multiplication unit 20. The partial symbol signal is provided to pilot symbolization integration unit 17 and processing delay unit 19.
[0028]
The pilot symbolization integration unit 17 restores pilot symbols included in the partial symbol signal. More specifically, the pilot symbolization integration unit 17 extracts a portion corresponding to the pilot symbol from the partial symbol signal provided from the partial despreading unit 14. Thereafter, the pilot symbolization integration unit 17 restores the original one-symbol-length pilot symbol by integrating a portion corresponding to the extracted pilot symbol a plurality of times. The pilot symbolization integration unit 17 gives the restored original pilot symbol to the channel estimation unit 18.
[0029]
The channel estimation unit 18 performs channel estimation based on the restored pilot symbol phase. Specifically, channel estimation unit 18 extracts a reference phase based on the phase of the pilot symbol, and provides this reference phase to complex multiplication unit 20.
[0030]
The processing delay unit 19 delays the partial symbol signal provided from the partial despreading unit 14 for a predetermined time. The predetermined time is set to a time equal to the time required for restoring the pilot symbols and extracting the reference phase. The processing delay unit 19 provides the delayed partial symbol signal to the complex multiplication unit 20.
[0031]
The complex multiplier 20 performs synchronous detection on the partial symbol signal based on the reference phase. More specifically, the complex multiplier 20 demodulates the partial symbol signal by narrowband by removing the reference phase component from the partial symbol signal. Thereby, it is possible to obtain a partial symbol signal in which the modulation is released. The demodulated partial symbol signal is provided to the symbolization integrator 21 as an output of the pilot synchronous detector 16.
[0032]
The symbolization integration unit 21 restores the original data symbol of one symbol length from the demodulated partial symbol signal. As described above, the partial symbol signal is a signal composed of partial symbols having a length of one symbol or less. Therefore, the symbolization integrator 21 reconstructs the original data symbol of one symbol length by repeatedly integrating the partial symbol signal until it becomes one symbol.
[0033]
FIG. 4 is a conceptual diagram for explaining in more detail processing from creation of a partial symbol signal to restoration of an original data symbol. As described above, the partial symbol signal is created by using the reference code of the partial spreading factor PSF having a length equal to the shortest spreading factor SF among the plurality of spreading factors SF set on the transmission side. That is, the partial despreading unit 14 multiplies the digital baseband signal and the reference code, and the multiplication result is a partial spreading factor PSF 2. ^P Discharge after integrating over the time corresponding to the chip.
[0034]
As a result, 2 ^M 1 symbol spread with a spreading code of the chip spreading factor SF is 2 ^P A partial symbol despread with a reference code of the partial spreading factor PSF of the chip can be obtained. In other words, if the ratio of the spreading factor SF and the despreading factor PSF used on the transmission side is R, the partial symbol length included in the partial symbol signal is 1 / R of one symbol.
[0035]
In this way, a partial symbol signal composed of 1 / R partial symbols of one symbol is supplied to the pilot symbolization integration unit 17 of the pilot synchronous detection unit 16. The pilot symbolization integration unit 17 extracts pilot symbols from the partial symbol signal. In this case, it is necessary to return the partial symbol to one symbol length. Therefore, the pilot symbolization integration unit 17 integrates a portion corresponding to the pilot symbol included in the partial symbol signal R times. By doing so, it is possible to restore a one-symbol pilot symbol.
[0036]
Further, a partial symbol signal composed of 1 / R partial symbols of one symbol length is given to the symbolizing integrator 21 after being subjected to synchronous detection. Even in this case, since it is necessary to return the partial symbol to one symbol, the symbolization integrator 21 integrates the partial symbol signal R times. In this way, a data symbol having a length of 1 symbol can be restored.
[0037]
As described above, according to the first embodiment, the partial despreading unit 14 only needs to perform despreading with the partial spreading factor PSF corresponding to the shortest spreading factor SF among the plurality of spreading factors SF. Timing design and operation verification need only be based on one type of partial spreading factor PSF. Further, the channel estimation unit 18, the processing delay unit 19 and the complex multiplication unit 20 need only design the operation timing for the partial spreading factor PSF. Only the pilot symbolization integration unit 17 and the symbolization integration unit 21 need to design the operation timing for all of the plurality of spreading factors SF.
[0038]
Therefore, it is possible to greatly reduce the trouble of designing the operation timing and the like as compared with the conventional technique in which the operation timing and the like must be designed in all of the plurality of spreading factors SF. Specifically, the time for designing the operation timing is roughly reduced to about half. Therefore, the manufacturing time of the spread spectrum demodulator 13 can be greatly shortened, and the manufacturing process can be greatly simplified. Therefore, the manufacturing cost of the spread spectrum demodulation unit 13 can be reduced.
[0039]
Further, even when a plurality of spread spectrum demodulation units 13 are manufactured and a spread spectrum signal created based on spreading codes of spreading factors SF as different fixed values is demodulated, the plurality of spread spectrum demodulation units 13 are manufactured. By manufacturing the spread spectrum demodulation unit 13 that performs despreading with the partial spread rate PSF having a length equal to the shortest spread rate SF among the spread rates SF, the manufacturing time of the plurality of spread spectrum demodulation units 13 is shortened. be able to.
[0040]
More specifically, let us consider a case where two types of demodulating devices, for example, a high-speed data communication demodulating device and an audio dedicated demodulating device are manufactured. The audio dedicated demodulator demodulates a spread spectrum signal created based on a relatively large spreading factor SF, for example, a 128 spreading code. The high-speed data communication demodulator demodulates a spread spectrum signal created based on a relatively small spreading factor SF, for example, 32 spreading codes. In this case, two types of spreading factors SF of 128 and 32 are set in advance. Further, the spreading factor SF in this case is expressed by a power of 2, and a relatively small spreading factor SF has a length that is 1 / power of 2 of a relatively large spreading factor SF.
[0041]
In the above case, the spread spectrum demodulator 13 that performs the despreading process using the shortest 32 reference codes of the two types of spreading factors SF as the partial spreading factor PSF is manufactured. More specifically, the spread spectrum demodulation unit 13 applied to the high-speed data communication demodulator includes a partial despreading unit 14 that performs a despreading process with 32 reference codes as the partial spreading factor PSF, and R A product including the pilot symbolization integration unit 17 and the symbolization integration unit 21 that perform integration processing at the number of times = 32/32 = 1 is manufactured. Further, the spread spectrum demodulator 13 applied to the audio dedicated demodulator includes a partial despreading unit 14 that performs a despreading process with 32 reference codes as a partial spreading factor PSF, and R = 128/32 = 4 Of the pilot symbolization integration unit 17 and the symbolization integration unit 21 that perform the integration processing at the number of times are manufactured.
[0042]
By doing so, the design and operation verification of the operation timing of the portions other than the pilot symbolization integration unit 17 and the symbolization integration unit 21 need only be performed based on one type of partial spreading factor PSF of 32. That is, the design of the operation timings of the high-speed data communication demodulator and the audio dedicated demodulator can be shared to some extent. Therefore, it is possible to greatly reduce the labor required for designing the operation timing. Therefore, the time for manufacturing the plurality of demodulation devices can be reduced as a whole, and the manufacturing process can be greatly simplified.
[0043]
In the above description, a length equal to the shortest spreading factor SF among the plurality of spreading factors SF is set as the length of the partial spreading factor PSF. However, for example, as the length of the partial spreading factor PSF, a length shorter than the shortest spreading factor SF among the plurality of spreading factors SF may be set. More specifically, the length of the partial spreading factor PSF is set to a length of 1 / integer of the shortest spreading factor SF, for example, half of the shortest spreading factor SF. This also does not change the effort required for operation timing design and the like, as in the above description.
[0044]
Embodiment 2
FIG. 5 is a block diagram showing the configuration of the spread spectrum demodulation unit 13 according to Embodiment 2 of the present invention. In FIG. 5, the same reference numerals are used for the same functional parts as in FIG.
[0045]
In the first embodiment, the case where pilot data is time-multiplexed and inserted into a data string has been described as an example. On the other hand, in the second embodiment, a case where pilot data is transmitted using a channel different from the data string is taken as an example.
[0046]
More specifically, in the second embodiment, the spread spectrum transmitter 3 spreads the pilot symbols with the first spreading code and spreads the data symbols with the second spreading code different from the first spreading code, A spread spectrum signal is created by code-multiplexing the pilot symbols with data symbols. Thus, in the second embodiment, since the pilot symbols are spread with a spreading code different from that of the data symbols, it is necessary to despread the pilot symbols and the data symbols separately on the receiving side.
[0047]
Therefore, the spread spectrum receiver 4 according to the second embodiment includes a pilot channel despreading unit 25 provided independently of the pilot synchronous detection unit 16 as a configuration for extracting pilot symbols. A digital baseband signal is supplied to the pilot channel despreading unit 25 in parallel with the partial despreading unit 14.
[0048]
The reference code generator 15 provided in the spread spectrum receiver 4 generates a first reference code that is the same chip sequence as the first spreading code and a second reference code that is the same chip sequence as the second spreading code. To do. The reference code generation unit 15 provides the first reference code to the pilot channel despreading unit 25 and the second reference code to the partial despreading unit 14.
[0049]
The pilot channel despreading unit 25 reconstructs pilot symbols by multiplying the digital baseband signal by the first spreading code. In this case, the digital baseband signal includes a pilot symbol having a length of one symbol. Therefore, unlike the first embodiment, it is possible to restore a one-symbol pilot symbol by simply performing despreading without performing R integrations. The pilot channel despreading unit 25 directly inputs the restored pilot symbol to the channel estimation unit 18 of the pilot synchronous detection unit 16.
[0050]
As described above, according to the second embodiment, even when a pilot symbol is inserted into a spread spectrum signal by code multiplexing, one kind of partial spreading factor is used in most of the spread spectrum demodulation unit 13 as in the first embodiment. Since it is only necessary to design and verify the operation timing for the PSF, it is possible to greatly reduce the effort required for designing the operation timing.
[0051]
Embodiment 3
FIG. 6 is a block diagram showing the configuration of the spread spectrum demodulator 13 according to Embodiment 3 of the present invention. In FIG. 6, the same reference numerals are used for the same functional parts as in FIG.
[0052]
The spread spectrum demodulation unit 13 according to the third embodiment is obtained by applying the configuration of the spread spectrum demodulation unit according to the first embodiment to RAKE reception. More specifically, the spread spectrum demodulation unit 13 includes a plurality of finger units 30. Each finger unit 30 separately despreads the spread spectrum signal propagated through different propagation paths based on the reference code given from the reference code generation unit 15.
[0053]
More specifically, the finger unit 30 includes a partial despreading unit 14, a pilot synchronous detection unit 16, and a symbolization integration unit 21, and further includes a first delay unit 31 and a second delay unit 32. . The first delay unit 31 delays the reference code over a time corresponding to the propagation delay time, and inputs the reference code to the partial despreading unit 14. The second delay unit 32 delays the data symbol output from the symbolization integration unit 21 over the same time as the first delay unit 31.
[0054]
In this configuration, the reference code generated by the reference code generation unit 15 is delayed by the first delay unit 31 of each finger unit 30 and then given to the partial despreading unit 14. As a result, the partial despreading unit 14 despreads the digital baseband signal at a timing according to the propagation delay time.
[0055]
The partial symbol signal obtained after despreading is synchronously detected by the pilot synchronous detector 16 and then integrated by the symbolization integrator 21 to be the original data symbol. This data symbol is delayed in the second delay unit 32. This delay time is the same as the delay time in the first delay unit 31. Therefore, the data symbols output from each finger unit 30 are timed with each other. Each finger unit 30 provides a data symbol to the RAKE combining unit 33.
[0056]
The RAKE combining unit 33 performs RAKE combining of the data symbols corresponding to the finger units 30. Thereby, a data symbol from which the influence of multipath fading is removed can be obtained.
[0057]
As described above, according to the third embodiment, even in the spread spectrum demodulation unit 13 that performs RAKE reception, the operation timing of one type of partial spreading factor PSF is almost the same as in the first embodiment. Since it is only necessary to perform design and operation verification, it is possible to greatly reduce the trouble of designing the operation timing.
[0058]
The configuration of the second embodiment may be combined with the configuration of the third embodiment. FIG. 7 is a block diagram illustrating a configuration of the spread spectrum demodulation unit 13 when the configuration of the second embodiment is combined with the configuration of the third embodiment. The spread spectrum demodulation unit 13 includes a pilot channel despreading unit 25 provided independently of the pilot synchronous detection unit 16 as a configuration for extracting pilot symbols. In this connection, each finger unit 30 includes a third delay unit 35 for providing a reference code delayed with respect to the pilot channel despreading unit 25. The delay time in the third delay unit 35 is the same as the first delay unit 31 of each finger unit 30.
[0059]
According to this configuration, even when pilot symbols are code-multiplexed and transmitted and RAKE reception is performed, in the end, most of the spread spectrum demodulator 13 has only one type of partial spreading factor PSF. Since it is only necessary to design and verify the operation timing, it is possible to greatly reduce the trouble of designing the operation timing.
[0060]
Embodiment 4
FIG. 8 is a block diagram showing the configuration of the spread spectrum demodulation unit 13 according to the fourth embodiment of the present invention. In FIG. 8, the same reference numerals are used for the same functional parts as in FIG.
[0061]
In the third embodiment, the operation timing of each finger unit 30 is set independently. On the other hand, in this Embodiment 4, the operation timing of each finger part 30 is made common.
[0062]
More specifically, the spread spectrum demodulation unit 13 includes a tapped delay unit 40. The tap delay unit 40 delays the digital baseband signal output from the A / D converter 12 over a time corresponding to the propagation delay time, and then extracts the digital baseband signal from the predetermined tap position. It gives to each finger part 30 at timing. Thereby, in each finger part 30, a process can be performed at a common timing.
[0063]
As described above, according to the fourth embodiment, the operation timing of the finger unit 30 is shared. When the operation timings of the finger units 30 are made independent as in the third embodiment, it is necessary to design and verify the operation timing of each finger unit 30 using different test patterns. However, if the operation timings of the finger units 30 are made common as in the fourth embodiment, it is only necessary to design the operation timings and verify the operations of each finger unit 30 using a common test pattern or the like. Therefore, it is possible to reduce the labor required for designing the operation timing. Therefore, the manufacturing time can be shortened and the manufacturing process can be simplified.
[0064]
The configuration of the second embodiment may be combined with the configuration of the fourth embodiment. FIG. 9 is a block diagram showing the configuration of the spread spectrum demodulation unit 13 when the configuration of the second embodiment is combined with the configuration of the fourth embodiment. The spread spectrum demodulation unit 13 includes a tapped delay unit 40 and a pilot channel despreading unit 25 provided independently of the pilot synchronous detection unit 16 as a configuration for extracting pilot symbols. In this connection, the digital baseband signal output from the tapped delay unit 40 is provided to the pilot channel despreading unit 25 and the partial despreading unit 14 in each finger unit 30. On the other hand, the reference code generation unit 15 gives the first reference code to the pilot channel despreading unit 25 of each finger unit 30 and also gives the second reference code to the partial despreading unit 14 of each finger unit 30. give.
[0065]
According to this configuration, even when a spread spectrum signal in which pilot symbols are inserted by code multiplexing is received by RAKE, the operation timing of each finger unit 30 can be made common. Compared with the case where it is independent, the effort required for the design of the operation timing and the operation verification can be greatly reduced.
[0066]
Embodiment 5
FIG. 10 is a block diagram showing a configuration of the spread spectrum demodulation unit 13 according to the fifth embodiment of the present invention. In FIG. 10, the same reference numerals are used for the same functional parts as in FIG.
[0067]
In the third embodiment, the pilot synchronous detection unit 16 is provided for each finger unit 30. On the other hand, in the fifth embodiment, the pilot synchronous detector 16 is made common to each finger unit 30, and this pilot synchronous detector 16 is used for each finger unit 30 in a time-sharing manner. Yes.
[0068]
More specifically, the spread spectrum demodulation unit 13 includes a plurality of finger units 30, one data selector unit 45, and one pilot synchronous detection unit 16. The finger unit 30 includes a first delay unit 31, a partial despreading unit 14, and a second delay unit 32. As in the third embodiment, the first delay unit 31 delays the reference code by a time corresponding to the propagation delay time. The second delay unit 32 delays the partial symbol signal output from the partial despreading unit 14 by the same time as the delay time in the first delay unit 31. In this case, the number of stages of the second delay unit 32 is R times that of the first delay unit 31. This is because the partial despreading unit 14 divides one symbol into R pieces. With the above configuration, each symbol unit 30 outputs a partial symbol signal with the timing matched.
[0069]
The partial symbol signal output from each finger unit 30 is provided to the data selector unit 45. The data selector 45 time-division multiplexes each partial symbol signal and gives it to the pilot synchronous detector 16. The pilot synchronous detector 16 performs synchronous detection on the partial symbol signals corresponding to each finger unit 30 in a time-sharing manner, and sequentially gives the demodulated partial symbol signals to the symbolizing integrator 21.
[0070]
The symbolization integration unit 21 executes a process of integrating the partial symbol signal R times in a time division manner. By doing so, the data symbols corresponding to each finger unit 30 can be obtained. Each data symbol is given to the RAKE combining unit 46 and is RAKE combined. Thus, the original data symbol is restored.
[0071]
As described above, according to the fifth embodiment, since only one pilot synchronous detector 16 is required, the circuit scale can be reduced. Therefore, the operation of the pilot synchronous detector 16 needs to be verified only once. Therefore, compared to the case where the operation timing design and operation verification of each pilot synchronous detection unit 16 must be performed for each of the plurality of finger units 30, it is possible to further reduce the effort required for the operation timing design and the like. Therefore, the manufacturing time can be further greatly shortened, and the manufacturing process can be greatly simplified.
[0072]
The configuration of the second embodiment may be combined with the configuration of the fifth embodiment. FIG. 11 is a block diagram illustrating the configuration of the spread spectrum demodulation unit 13 when the configuration of the second embodiment is combined with the configuration of the fifth embodiment. The spread spectrum demodulation unit 13 includes one pilot synchronous detection unit 16 and a pilot channel despreading unit 25 in each finger unit 30. Each finger unit 30 includes a third delay unit 35 that delays the first reference code to be provided to the pilot channel despreading unit 25. Further, each finger unit 30 includes a fourth delay unit 50 that delays the pilot symbols output from the pilot channel despreading unit 25. As a result, the pilot channel despreading unit 25 can reliably restore the pilot symbols regardless of the propagation delay time, and can output the restored pilot symbols from the finger unit 30 at the same timing.
[0073]
Furthermore, the spread spectrum demodulation unit 13 includes a pilot selector unit 51. The pilot selector unit 51 gives the pilot symbols output from each finger unit 30 to the channel estimation unit 18 in the pilot synchronous detection unit 16. More specifically, the pilot selector 51 provides time division multiplexing of pilot symbols to the channel estimator 18 in order to use the pilot synchronous detector 16 in time division.
[0074]
According to this configuration, the pilot synchronous detection unit 16 is shared by the plurality of finger units 30 even when a spread spectrum signal in which pilot symbols are inserted by code multiplexing is received. Therefore, as in the above description, the design and operation verification of the operation timing of the pilot synchronous detector 16 need only be performed for one despreading operation, and therefore the effort required for the operation timing design and the like can be further reduced. .
[0075]
Embodiment 6
FIG. 12 is a block diagram showing the configuration of the spread spectrum demodulation unit 13 according to the sixth embodiment of the present invention. In FIG. 12, the same reference numerals are used for the same functional parts as those in FIGS.
[0076]
In the fifth embodiment, each finger unit 30 operates at an independent timing. On the other hand, in this Embodiment 6, the operation timing of each finger part 30 is made common. That is, the spread spectrum demodulator 13 according to the sixth embodiment combines a common configuration of the pilot synchronous detector 16 in the fifth embodiment and a common configuration of the operation timing of the finger unit 30 in the fourth embodiment. It has become.
[0077]
More specifically, as in the fourth embodiment, the spread spectrum demodulator 13 includes a tapped delay unit 40 that applies a digital baseband signal to each finger unit 30 at the same timing. The output of the finger unit 30 is given to the data selector unit 45, and the partial symbol signal is given from the data selector unit 45 to one pilot synchronous detection unit 16 by time division. The pilot synchronous detector 16 performs synchronous detection processing of the partial symbol signal for each finger unit 30 and outputs the result to the symbolization integrator 21. The symbol integration unit 21 integrates the partial symbol signals corresponding to each finger unit 30 to restore the data symbols corresponding to each finger unit 30. Thereafter, the RAKE combining unit 46 RAKE combines the data symbols for each finger unit 30. In this way, a final data symbol can be obtained.
[0078]
As described above, according to the sixth embodiment, the pilot synchronous detection unit 16 is shared by the plurality of finger units 30, and the operation timing of the finger unit 30 is also shared. In comparison, it is possible to further reduce the effort required for operation timing design and operation verification.
[0079]
The configuration of the second embodiment may be combined with the configuration of the sixth embodiment. FIG. 13 is a block diagram showing the configuration of the spread spectrum demodulation unit 13 when the configuration of the second embodiment is combined with the configuration of the sixth embodiment. The spread spectrum demodulator 13 shares the pilot synchronous detector 16 with a plurality of finger units 30, includes a tapped delay unit 40, and further extracts each pilot symbol from the pilot synchronous detector 16 as a configuration for extracting pilot symbols. An independent pilot channel despreading unit 25 is provided in the unit 30.
[0080]
According to this configuration, even when pilot symbols are inserted into the spread spectrum signal by code multiplexing, the operation timing of each finger unit 30 can be made common, and the pilot synchronous detection unit 16 is provided with a plurality of finger units 30. Therefore, it is possible to reduce the effort required for operation timing design and operation verification.
[0081]
Other embodiments
The description of the embodiment of the present invention is as described above, but the present invention is not limited to the above-described embodiment. For example, in the above embodiment, the case where the spread spectrum receiver 4 is provided in the mobile station 2 is taken as an example. However, the spread spectrum receiver 4 may be provided in the base station 1 as a matter of course.
[0082]
【The invention's effect】
As described above, according to the present invention, in a spread spectrum demodulator in which a plurality of spreading factors are preset and active correlation processing is performed, a length equal to or shorter than the shortest spreading factor among the plurality of spreading factors. A partial symbol signal is generated by executing active correlation processing based on the reference code of the partial spreading factor having, and after performing pilot synchronous detection, the original data symbol is restored by integrating the partial symbol signal. Yes.
[0083]
Therefore, only the extraction of pilot symbols and the integration of partial symbol signals during pilot synchronous detection depend on the spreading factor used. Therefore, it is possible to reduce the effort required for designing the operation timing and the like, compared to the case where the operation timing is designed or verified according to a plurality of spreading factors in all portions. Therefore, the manufacturing time of the spread spectrum demodulator can be shortened and the manufacturing process can be simplified.
[0084]
In addition, when the partial despreading unit, the pilot synchronous detection unit, and the symbolization integration unit are respectively provided in a plurality of finger units, that is, when RAKE reception is performed, the time required for operation verification decreases in inverse proportion to the number of finger units. . Therefore, it is possible to further reduce the time and effort required for operation timing design and operation verification, and to further simplify the manufacturing time.
[0085]
Furthermore, when the spread spectrum signal is input to the finger unit at a timing corresponding to the propagation delay time, it is not necessary to operate each finger unit at an independent timing, so the operation timing design and operation verification of each finger unit is not necessary. Can be performed by the same operation timing chart. Therefore, it is possible to further reduce the labor required for designing the operation timing.
[0086]
Furthermore, even when pilot symbols are spread with a spreading code different from that of data symbols, only the extraction of pilot symbols and the integration of partial symbol signals during pilot synchronous detection depend on the spreading factor used. It is possible to reduce the time and effort required for operation timing design and operation verification.
[0087]
Furthermore, when the pilot synchronous detection unit is shared by a plurality of finger units, it is not necessary to perform the operation verification as the pilot synchronous detection unit for each finger unit. The effort required for operation verification can be further reduced. Therefore, it is possible to further shorten the manufacturing time and simplify the manufacturing process.
[0088]
Furthermore, in this case, when the spread spectrum signal is input to the finger unit at a timing according to the propagation delay time, the design and operation verification of the operation timing of each finger unit can be performed with the same operation timing chart. It is possible to further reduce the labor required for designing the operation timing.
[0089]
Furthermore, even when the pilot symbol is spread with a spreading code different from that of the data symbol, it is possible to reduce the effort required for the design of the operation timing and the operation verification as described above.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a configuration of a mobile communication system to which a spread spectrum demodulation apparatus according to Embodiment 1 of the present invention is applied.
FIG. 2 is a diagram for explaining a difference in the number of symbols due to a difference in spreading factor;
FIG. 3 is a block diagram showing a configuration of a spread spectrum receiver according to the first embodiment.
FIG. 4 is a diagram for explaining partial symbolization and symbol restoration.
FIG. 5 is a block diagram showing a configuration of a spread spectrum demodulator according to Embodiment 2 of the present invention.
FIG. 6 is a block diagram showing a configuration of a spread spectrum demodulator according to Embodiment 3 of the present invention.
FIG. 7 is a block diagram showing a configuration in the case of demodulating a spread spectrum signal in which data symbols and pilot symbols are code-multiplexed in a spread spectrum demodulator according to the third embodiment.
FIG. 8 is a block diagram showing a configuration of a spread spectrum demodulator according to Embodiment 4 of the present invention.
FIG. 9 is a block diagram showing a configuration when a spread spectrum signal in which data symbols and pilot symbols are code-multiplexed is demodulated in a spread spectrum demodulator according to a fourth embodiment.
FIG. 10 is a block diagram showing a configuration of a spread spectrum demodulator according to Embodiment 5 of the present invention.
FIG. 11 is a block diagram showing a configuration in the case of demodulating a spread spectrum signal in which data symbols and pilot symbols are code-multiplexed in a spread spectrum demodulator according to the fifth embodiment.
FIG. 12 is a block diagram showing a configuration of a spread spectrum demodulator according to Embodiment 6 of the present invention.
FIG. 13 is a block diagram showing a configuration in the case of demodulating a spread spectrum signal in which data symbols and pilot symbols are code-multiplexed in a spread spectrum demodulator according to the sixth embodiment.
FIG. 14 is a block diagram showing a configuration of a conventional spread spectrum demodulator.
[Explanation of symbols]
13 spread spectrum demodulation unit, 14 partial despreading unit, 16 pilot synchronous detection unit, 17 pilot symbolization integration unit, 21 symbolization integration unit, 25 pilot channel despreading unit, 30 finger unit, 33 RAKE combining unit, 40 with tap Delay unit, 45 data selector unit, 46 RAKE combining unit, 51 pilot selector unit.

Claims (4)

A spread spectrum demodulator that demodulates a spread spectrum signal that is created based on a spreading code of any one of a plurality of spreading factors set in advance and includes pilot symbols and data symbols,
Active correlation processing is performed on the spread spectrum signal based on a reference code of a partial spreading factor that is provided in each of a plurality of finger sections and has a length equal to or shorter than the shortest spreading factor among the plurality of spreading factors. A partial despreading unit for obtaining a partial symbol signal composed of partial symbols having a length of 1 symbol or less,
A data selector unit for time-division multiplexing and outputting the partial symbol signals output from each finger unit;
A pilot synchronous detection unit common to the finger units for synchronously detecting the partial symbol signals corresponding to the finger units output from the data selector unit in a time division manner;
Symbolizing integrators that respectively restore data symbols corresponding to the respective finger parts by integrating the partial symbol signals corresponding to the respective finger parts after the synchronous detection by the pilot synchronous detecting part in a time-sharing manner,
A spread spectrum demodulating apparatus comprising: a RAKE combining unit that performs RAKE combining of data symbols corresponding to each finger unit restored by the symbolizing integration unit. 2. The symbolizing integrator according to claim 1, wherein the symbol integration unit restores the data symbol by integrating the partial symbol signal after the synchronous detection over a number of times corresponding to a ratio of a spreading factor and a partial spreading factor of the spread signal. A spread spectrum demodulator characterized by the above. 3. The spread spectrum demodulator according to claim 1, further comprising a delay unit that outputs the spread spectrum signal to each finger unit at a timing corresponding to the propagation delay time. In any one of Claims 1 thru | or 3 , each finger part further has a pilot symbol despreading part which extracts the pilot symbol spread | diffused with the spreading code different from a data symbol from the said spread spectrum signal,
A pilot selector that outputs the pilot symbols extracted by the pilot symbol despreading unit of each finger in a time division manner;
The pilot synchronous detection unit is configured to synchronously detect a partial symbol signal corresponding to each finger unit based on a pilot symbol corresponding to each finger unit output in a time division manner from the pilot selector unit. A spread spectrum demodulator.

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