JP3795326B2 - CDMA receiving apparatus and CDMA receiving method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a receiving apparatus in a base station of a mobile communication system using, for example, a CDMA system, and is particularly suitable for use as a matched filter for synchronization supplementation and synchronization holding for demodulating a code-multiplexed radio signal. The present invention relates to a CDMA receiving apparatus and a CDMA receiving method.
[0002]
[Prior art]
In recent years, the number of mobile phone subscribers has increased dramatically, and mobile communication operators have adopted a CDMA (Code Division Multiple Access) system in order to accommodate more subscribers. As is well known, a transmission device (transmitter) multiplies data to be transmitted by a spread code (Spread Code) such as a Pseudo Noise code (PN code) to generate spread data and up-convert it. Thus, a code-multiplexed radio signal (RF signal: Radio Frequency signal) is transmitted. Then, the receiving device (receiver) receives the RF signal, down-converts, and further multiplies the down-converted signal by the same replica code (despreading code) as the spreading code to despread (Despread). ) To demodulate.
[0003]
FIG. 19 is a diagram illustrating a main part of a CDMA receiver. The receiving apparatus 50 shown in FIG. 19 is provided in a base station in mobile communication. The receiving device 50 receives the code-multiplexed RF signal at the antenna 50a. This received signal is band-limited by a band-pass filter (band-limiting) 50b, amplified by a low noise amplifier (LNA) 50c, and input to a frequency converter 50d. The frequency converter 50d has a local oscillator (not shown), down-converts the signal output from the LNA 50c using a local signal output from the local oscillator, and outputs a baseband signal.
[0004]
Further, the baseband signal is converted into digital data by an analog / digital converter (A / D converter) 50e. The digital data is input to each of the delay profile measuring unit 50h and the despreading processing unit 50f.
Further, the delay profile measuring unit 50h shown in FIG. 19 measures a delay profile in order to obtain path timing. The delay profile measuring unit 50h includes a matched filter (digital matched filter) 51a and an averaging processing unit (Σ) 51b.
[0005]
As is well known, a receiving apparatus receives delayed waves that have arrived through a plurality of propagation paths (multipaths) having different distances, and thus generates a plurality of signals having time intervals corresponding to the distance difference. . This multipath characteristic is defined as various parameters in transmission experiments and simulations. Here, a parameter representing how much the delay amount spreads in the time direction is called a delay profile, and represents the shape of the spread of the power distribution with respect to the delay time. Note that the dispersion value of the delay profile is called a delay spread.
[0006]
FIG. 20A is a diagram illustrating an example of the delay profile measuring unit 50h. The delay profile measuring unit 50h shown in FIG. 20A includes 4-tap shift registers (hereinafter, may be abbreviated as registers) 60a and 60b, and four EXOR circuits 60c. Here, the receiver knows the spreading code used by the transmitter, and loads the replica code from the code generator 50j to the register 60b. The matched filter 51a loads the digital data input from the A / D converter 50e into the register 60a, and EXORs the replica code loaded into the register 60a by the EXOR circuit 60c and the digital data. The results are added by the averaging processing unit 51b, and the added value is output as the number (correlation value) in which the data and the code match.
[0007]
FIG. 20B is a diagram for explaining the delay profile measurement method, and shows an example of the relationship between time and the number of matches. In the delay profile measuring unit 50h, first, the matched filter 51a stores the replica code “1001” in the register 60b, and then inputs the received data “1001” to the register 60a bit by bit. When the leading “1” of the received data is input to the register 60a, the corresponding replica code is “1”, so the number of matches is 1. Further, after one chip time, the received data shifted is “01”. At this time, since the corresponding replica code is “10”, the number of matches is zero. Further, after one chip time, the received data shifted is “001”, and the corresponding replica code is “100”, so the number of matches is 1. Since the shifted received data is “1001” and the corresponding replica code is also “1001”, all the bits match and the number of matches is output as 4.
[0008]
Accordingly, the delay profile measuring unit 50h shown in FIG. 19 measures the delay profile, outputs the correlation value of the delay profile, and outputs the correlation value to the delay amount / path detecting unit 50i as the reception level. The correlation value is output corresponding to the time, and the value of the correlation value output changes corresponding to the reception level.
Next, the delay amount / path detection unit 50i will be described with reference to FIGS.
[0009]
FIGS. 21A to 21C are diagrams for explaining the operation of the delay amount / path detection unit 50i. In FIG. 21A, (1) represents a direct arrival wave (direct wave), and (2) and (3) both represent a delayed arrival wave (delayed wave). The receiving device receives the RF signal in a state where all the waves appear to overlap.
Further, data {circle around (1)} to {circle around (3)} shown in FIG. 21 (b) each have a delay time corresponding to the wave shown in FIG. 21 (a). Then, the delay amount / path detection unit 50i detects the number of incoming waves and the delay time by using previously input delay profile data. Further, the delay amount / path detection unit 50i calculates the path timing at which the direct wave and the delayed wave arrive, and the code generation unit 50g uses the pulses (1) to (3) shown in FIG. To be notified.
[0010]
Here, the reason why the receiving device obtains the path timing is to improve the quality of the received signal by combining the plurality of incoming waves and using, for example, maximum ratio combining.
Next, the despreading processing unit 50f shown in FIG. 19 despreads the digital data by multiplying the digital data by a replica code, and the function is realized by, for example, a sliding correlator. In order to obtain this replica code, a code generator 50g is provided.
[0011]
In addition, the despreading processing unit 50f receives the timing for matching the beginning of the replica code and the beginning of the digital data from the delay amount / path detecting unit 50i. This timing is referred to as path timing, and corresponds to a time delay interval between the direct wave and the delayed wave observed by the receiving apparatus.
Then, the despreading processing unit 50f detects the correlation by synchronizing the digital data with the replica code. This correlation detection function is realized by a sliding correlator.
[0012]
FIG. 22A is a diagram for explaining the despreading process. The despreading processing unit 50f shown in FIG. 22A performs processing corresponding to each of the direct wave and the delayed wave in the multipath, and a replica code is stored in advance in the code generation unit 50g. . Then, the despreading processing unit 50f receives the path timing measured by the delay profile measuring unit 50h via the delay amount / path detection unit 50i. Based on the path timing, the despreading processing unit 50f The correlation is calculated.
[0013]
Further, by this correlation calculation, the digital data is demodulated and the original data is demodulated. FIG. 22B is a diagram showing an example of a time chart showing the despreading operation between the replica code and the received data. The digital data is EXORed with the replica code, and the processed received data is generated.
As described above, at the time of CDMA reception, the receiving apparatus detects the correlation by synchronizing the spread code multiplied by the received data with the despread code used for despread demodulation. This correlation detection is performed using a matched filter.
[0014]
FIG. 23 is a diagram showing an example of the configuration of the matched filter 51a. In the matched filter 51a shown in FIG. 23, the A / D converted digital data has m stages (m represents a natural number. In FIG. 23, 256 stages). ) Flip-flops (FF: Flip Flop, hereinafter referred to as “tap”). On the other hand, the replica code is also loaded into a shift register (256 stages in FIG. 23) consisting of m stages of FFs, and when 256 chips of data are loaded, the replica code is stored in the latch unit (latch circuit, latches 1 to 256 and (Represented). Then, every other received data sequentially loaded into the shift register is extracted from the tap output and input to the adder. That is, the matched filter 51a has a large number of taps and latches.
[0015]
FIG. 24 is a diagram showing a time chart showing the relationship between received data and tap output. The 256 tap output (256 tap output) to 254 tap output (254 tap output) shown in FIG. 24 are shifted by one clock (1 CLK). Note that this one clock cycle is the reciprocal of the sampling rate of the A / D converter, and is 1 / 15.36 MHz (megahertz).
[0016]
Various techniques related to the matched filter have been proposed.
Japanese Laid-Open Patent Publication No. 2000-101473 (hereinafter referred to as publicly known document 1) discloses a matched filter device that can greatly reduce power consumption.
Japanese Patent Application Laid-Open No. 11-127134 (hereinafter referred to as “publicly known document 2”) can perform cell search at higher speed, can cope with multimedia transmission, and has multipath fading. A signal receiving apparatus in the DS-CDMA cellular system that can receive a signal with good reception quality even in an environment in which it occurs is disclosed.
[0017]
[Problems to be solved by the invention]
However, only the received data generated by one call (channel) can be processed using one matched filter in the base station. In addition, since the base station uses diversity, the base station needs to provide a plurality of matched filters in order for the base station to simultaneously acquire delay profiles for a plurality of received waves.
[0018]
Furthermore, since the circuit scale of the matched filter itself is large, providing a plurality of matched filters in the receiving device of the base station increases the circuit scale and wastes power consumption.
In addition, when the mobile station crosses adjacent sectors (area obtained by dividing one cell into six), the load of the base station is increased. That is, the base station must process received signals from four antennas, two antennas provided in the sector from which the mobile station is traversed and two antennas provided in the sector to which the mobile station is traversed. Don't be. Therefore, a very large circuit is required for the base station to despread the received signal from each antenna.
[0019]
Also, the correlation value output from the matched filter is selected from among a plurality of correlation values that has the maximum number of matches. Therefore, since the circuit scale is large for the correlation calculation, it is difficult to provide a matched filter for each call.
Therefore, in order to process a plurality of calls, the receiving apparatus has to measure the delay profile by using the matched filter and occupying the matched filter for each call.
[0020]
FIG. 25 is a diagram for explaining channel time division. Each of ch1 (channel 1) to ch16 (channel 16) shown in FIG. 25 represents a call received by the base station. Then, the receiving device of the base station assigns one matched filter to 16 calls of channels 1 to 16 by time division. Here, the longer the number of calls, the longer the time that one matched filter is occupied. Therefore, the time interval T allocated to each call becomes longer. A longer matched filter allocation interval T means a longer delay profile measurement period.
[0021]
FIGS. 26A and 26B are diagrams for explaining delay profile measurement periods. The reception levels shown in FIGS. 26A and 26B are based on the first measurement and the second measurement, respectively. Here, the base station performs the second despreading for the same channel using the replica code used for the first time.
[0022]
Therefore, when a mobile station in communication moves in a cell (or sector) at a high speed and moves away from the base station, the base station cannot accurately despread the received data, and errors increase. It becomes impossible to follow the change of the delay profile. For this reason, the base station causes a deterioration in the quality of the demodulated data for the received wave.
Moreover, the technique described in the publicly known document 1 aims at power saving, and does not mention the circuit scale.
[0023]
Furthermore, the technique described in the publicly known document 2 uses a plurality of matched filters and adaptively controls the correlation processing executed in the matched filters according to the operation state. Is not mentioned.
The present invention has been devised in view of such problems, and in a receiving apparatus of a base station using the CDMA system, it is not necessary to use a matched filter without mounting a plurality of matched filters, and a circuit is provided. It is an object of the present invention to provide a CDMA reception apparatus and a CDMA reception method that can perform a plurality of call processing without increasing the scale and can follow a mobile station moving at high speed.
[0024]
[Means for Solving the Problems]
  For this reason, the CDMA receiver of the present invention has one of received data caused by each of a plurality of code-multiplexed radio frequency signals and one of the same copy data as one of the plurality of received data. A plurality of unit matched filters for multiplying the selection data by the replica code and adding and outputting the multiplication result.SaidwirelessfrequencyBased on the delay profile measurement unit that outputs each reception level of the signal and the reception level output from the delay profile measurement unitThe abovewirelessfrequencyOutputs the timing of signal arrival and delay profile measurement unitControl the selection action atMultiple unit matched filterswhileofControl connection statusAnd a delay amount output unitThe
[0025]
  The delay amount output unit isSpecified based on the number of tap stages to which multiple unit matched filters are connectedThe plurality of operation modes may be configured to be switched and controlled in consideration of the number of blocks representing the number of blocks combined with a predetermined number of unit matched filters among the plurality of unit matched filters.Yes.
  The delay amount output unit includes at least one of a case where a new call occurs, a case where the reception state is stable, and a case where the correlation level of the delay profile is reduced.SaidIt can also be configured to switch between operating modesThe
[0026]
  The CDMA receiver of the present invention isDue to each of multiple radio frequency signals code-multiplexedOne of the received data andSame as one of multiple received dataA selector that selects one of the copy data and holds and outputs the selected data;SaidThe selection data output from the selector is multiplied by the replica code, and the multiplication result is added and output, and a plurality of blocks having a unit matched filter that outputs the selection data by delaying are provided, and the preceding block is provided. Delayed selection dataIn the next blockThe multiple blocks are connected in multiple stages to be input to the selector,SaidMultiple blocksInThe selector selects and outputs one of a plurality of received data other than those input to a plurality of blocks up to the preceding stage and the selection data delayed in the preceding block. And a delay profile measurement unit configured to output each reception level of the radio signal, and based on the reception level output from the delay profile measurement unit,wirelessfrequencyOutput the path timing when the signal arrives,Control selector selection in the multiple blocksMultiple unit matched filterswhileofControl connection statusIt is characterized by having a delay amount output sectionThe
[0027]
  In addition, a CDMA reception method includes a plurality of code-multiplexed radios.frequencyMultiple radios by despreading at least one of the signalsfrequencySpecific radio of one of the signalsfrequencyA despreading step for outputting processed data on the signal, a measuring step for measuring a delay profile of the processed data output in the despreading step for a predetermined time, and a specific radio based on the delay profile obtained by the measurementfrequencyA reception level output step for outputting the reception level of the signal, and a plurality of unit matched filters based on the reception levelwhileofConnection statusIt is characterized by having a switching step for switchingThe
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
(A) Description of the first embodiment of the present invention
FIG. 1 is a configuration diagram of a mobile communication system according to a first embodiment of the present invention. A mobile communication system (hereinafter sometimes abbreviated as a system) 20 shown in FIG. 1 provides a telephone service, a data transmission service, and an information providing service using a CDMA system. A plurality of mobile stations 21.
[0029]
Here, the base station 22 is a fixed station, for example, which is connected to a telephone network or the Internet network, and a plurality of call data (channel data) from the network side is code-multiplexed using several tens to 100 types of spreading codes. Then, the code-multiplexed RF signal is transmitted to the mobile station 21 and the RF signal transmitted from the mobile station 21 is received. Furthermore, the mobile station 21 communicates wirelessly with the base station 22 and is, for example, a mobile phone or a mobile information terminal.
[0030]
The RF signals transmitted and received between the mobile station 21 and the base station 22 all reach the antennas of the mobile station 21 and the base station 22 through a plurality of multipaths having different distances. Accordingly, the mobile station 21 and the base station 22 receive both the direct wave and the delayed wave (reflected wave) that is reflected by the building 23a and the mountain (natural object) 23b. For this reason, the delayed wave reaches the receiving devices of the mobile station 21 and the base station 22 after a time corresponding to the distance difference from the arrival of the direct wave.
[0031]
Then, the receiving device of the base station 22 demodulates the delayed wave and generates a reception pulse. The received pulse generated by the delayed wave is called a delayed pulse. This delay pulse has a spread in the time direction, and this spread is defined as a delay profile.
The cell 61 shown in FIG. 1 is divided into six sectors 62 with the base station 22 as the center.
[0032]
Hereinafter, a signal flow from the mobile station 21 to the base station 22 will be mainly described. The base station 22 shown in FIG. 1 also has a transmission device, and the mobile station 21 has a reception device, but details of the flow of transmission from the base station 22 to the mobile station 21 are omitted. .
FIG. 2 is a diagram illustrating a main part of the receiving device of the base station 22 according to the first embodiment of the present invention. A CDMA mobile receiver (CDMA receiver, hereinafter referred to as receiver) 25 shown in FIG. 2 is provided in the base station 22 and receives a code-multiplexed RF signal. , 50-8, a despreading processing unit 50f, replica code generation units (code generation units) 50g, 50j, and a delay profile measurement unit 1 (hereinafter referred to as “delay spread measurement unit 1”). And a delay amount / path detection unit (delay amount output unit) 8.
[0033]
Here, each of the RF units 50-1 to 50-8 receives the code-multiplexed RF signal transmitted from each of the plurality of mobile stations 21, and includes an antenna 50a, a bandpass filter 50b, A low noise amplifier 50c, a frequency converter 50d, and an A / D converter 50e are provided.
Here, the antenna 50a receives a code-multiplexed RF signal, and the band-pass filter 50b limits the frequency component determined by the specifications of the system 20 in the RF signal output from the antenna 50a. This is to improve the SN (Signal Noise) ratio. The antenna 50a can transmit an RF signal.
[0034]
The low noise amplifier 50c amplifies the RF signal output from the bandpass filter 50b with low noise and outputs the amplified RF signal. For example, an amplifier IC (Integrated Circuit) is used. Further, the frequency converter 50d performs frequency conversion on the amplified signal output from the low noise amplifier 50c, and has a local oscillator and a mixer that can output a local signal having a radio frequency band, although not shown. . In addition, the frequency of the local oscillator can be changed.
[0035]
In addition, the A / D converter 50e performs analog / digital conversion on the amplified signal output from the frequency converter 50d. The A / D converter 50e uses, for example, an IC, and there are a plurality of types of digital output bits. For this reason, the A / D converter 50e is used to output 16-bit data in total in order to improve the accuracy of the digital conversion value. Here, 8 bits out of 16 bits represent the I channel, and 8 bits represent the Q channel.
[0036]
As a result, the code-multiplexed RF signal is received by each of the antennas 50a of the RF units 50-1 to 50-8, the RF signal is band-limited by the band pass filter 50b, and amplified by the low noise amplifier 50c. The amplified signal is input to the frequency converter 50d. Further, the baseband signal obtained by frequency-converting the RF signal using the local signal from the local oscillator is obtained by the frequency converter 50d, and this baseband signal is converted into 16-bit digital data by the A / D converter 50e. It is converted.
[0037]
In addition, one call is processed by using one RF unit 50-1 by the above analog / digital conversion. This one call represents one channel and corresponds to reception data # 1 described later. Similarly, each of the RF units 50-2 to 50-8 processes a call different from that of the RF unit 50-1, and corresponds to each of received data # 2 to # 8 described later.
[0038]
The RF units 50-1 to 50-8 each have a transmission unit, although not shown. That is, each transmission unit first modulates data to be transmitted using, for example, QPSK (Quadrature Phase Shift Keying), code spreads, upconverts the spread data to generate an RF signal, The RF signal is transmitted from the antenna 50a.
[0039]
The despreading processing unit 50f despreads the digital data output from each of the RF units 50-1 to 50-8, and this function is realized by, for example, a sliding correlator. That is, the despreading processing unit 50f receives the path data for matching the beginning of the replica code (despreading code) and the beginning of the received data from the delay amount / path detecting unit 50i, thereby converting the received data into the replica code. The correlation is detected in synchronization with the above. This path timing corresponds to a time delay interval between the direct wave and the delayed wave observed by the receiving device 25.
[0040]
Each of the replica code generation units 50g and 50j generates a replica code, and this function is realized by, for example, a cyclic shift register. The despreading processing unit 50f multiplies the digital data by the replica code input from the code generating unit 50g to despread the digital data, and outputs the despread data as received data. Demodulation is performed by a circuit at a subsequent stage.
[0041]
Further, the measurement unit 1 is the same as one of the reception data # 1 to # 8 and one of the plurality of reception data # 1 to # 8 resulting from, for example, eight RF signals that are code-multiplexed. One of the copy data is selected, selection data (reception data # 1 to # 8 or reception data # 0) is held and output, the selection data is multiplied by the replica code, and the multiplication result is added and output 8 The unit matched filters 2a to 2h are provided and output the respective reception levels of the RF signals.
[0042]
That is, the measuring unit 1 measures the delay profile of the received wave, estimates the path timing of the received wave based on the measurement result, and notifies the despreading processing unit 50f.
Here, the reception data # 0 represents the same copy data as one of the eight types of reception data # 1 to # 8.
[0043]
FIG. 3 is a block diagram of the measurement unit 1 according to the first embodiment of the present invention, and a delay amount / path detection unit 8 is connected to the measurement unit 1. The measurement unit 1 shown in FIG. 3 includes a divided matched filter 13 that performs despreading, and an average calculation unit 11 that averages the output from the divided matched filter 13.
The divided matched filter 13 will be described with reference to FIGS. 4 and 5, and the average calculator 11 will be described with reference to FIG.
[0044]
FIG. 4 is a block diagram of the divided matched filter 13 according to the first embodiment of the present invention. The divided matched filter 13 shown in FIG. 4 includes eight selectors (SEL) 3a to 3h and eight pieces. Unit matched filters (hereinafter sometimes abbreviated as “matched filters”) 2 a to 2 h and a full adder 12. The selectors 3a to 3h are provided on the input side of the matched filters 2a to 2h, respectively. The selector 3a and the matched filter 2a form one block, and these blocks are connected in eight stages. ing. In the following description, only the matched filter 2a (or the matched filters 2b to 2h) that does not include the selectors 3a to 3h may be referred to as a block.
[0045]
The divided matched filter 13 receives data (reception data # 1 to # 8) corresponding to eight calls output from the RF units 50-1 to 50-8. . Here, the reception data # 0 is the same copy data as one of the eight types of reception data # 1 to # 8. For example, reception data # 0 is serial reception data when a delay profile is acquired in a 256-tap matched filter configuration, and is input to the selector 3a on the input side.
[0046]
The selector 3a receives received data # 0 and received data # 1, and selects one of them to output selected data (received data # 0 or # 1). The selector 3a receives a coupling control signal from the coupling control unit 7 (see FIG. 3), selects the reception data # 1 when the logic of the coupling control signal is 1, and receives the data # 0 when the logic is 0. Is selected and output. The functions of the selector 3a and selectors 3b to 3h described later are realized by logic circuits. Note that the logic of the coupling control signal can be reversed. This coupling control signal will be described later with reference to FIGS. 9A to 9C.
[0047]
The output selection data is input to the matched filter 2a.
FIGS. 5A and 5B are diagrams showing examples of connection relationships of the selectors 3a to 3h according to the first embodiment of the present invention. Each of the selectors 3a to 3h shown in FIG. 5A is configured to receive the received data # 1 to # 8 and the coupling control signal, and the selector 3a receives the received data # 0. Have been entered.
[0048]
Furthermore, each of the selectors 3a to 3h can be connected as shown in FIG. That is, the selector 3a receives the received data # 0, # 1 and the coupling control signal, and the selector 3b receives the received data # 0, # 2 and the coupling control signal.
In FIG. 4, for example, code-multiplexed RF signals transmitted by eight mobile stations 21 on each channel are transmitted to eight RF units 50-1 to 50-8 at the base station 22 (see FIG. 3). Are demodulated respectively. That is, since each of the eight channels of received data # 1 to # 8 is input and processed, the measuring unit 1 can selectively process each call.
[0049]
The matched filter 2a (see FIG. 4) calculates the correlation between the digital data and the replica code, and includes 32 first taps 1 to 32 (shown as taps 1 to 32), 32 EXOR circuits, 32 latches 1 to 32 (labeled as latches 1 to 32), 32 second taps (to which a despread code is input), and one adder And have.
[0050]
Here, each of the 32 first taps 1 to 32 is equal to the number of taps 32 for holding the received data, and functions as a finite state holding unit representing a binary value of 0 or 1. These functions are realized by a flip-flop (FF). Further, these 32 first taps 1 to 32 are connected in cascade (in series) so as to function as one shift register for received data (see FIG. 6 described later). That is, the bit string of the received data # 1 is shifted to tap 32, tap 31,.
[0051]
As a result, the unit matched filter 2a can adaptively combine / divide the other unit matched filters 2b to 2h with 32 taps as a basic unit, and can process received data efficiently.
Each of the 32 second taps also holds a binary value of 0 or 1, and is realized by a flip-flop. These 32 second taps are connected in cascade to function as one despreading shift register, and the bit string of the replica code shifts the 32 second taps in order. It has become.
[0052]
Furthermore, each of the 32 latches 1 to 32 can output a replica code. Each of these latches 1 to 32 latches (captures) the value of 0 or 1 of 32 second taps. Here, whether or not to latch the value is controlled by a code latch enable signal (enable signal) input from the outside. For example, when the logic of the enable signal is 1, the latch units 1 to 32 latch the respective values of the 32 second taps. When the logic of the enable signal is 0, for example, 32 latches. The latch of each value of the tap is stopped. Note that this logic can be reversed.
[0053]
Next, the 32 EXOR circuits each EXOR the outputs from the 32 first taps 1 to 32 and the outputs from the 32 latches 1 to 32 and input the EXOR results to the adder. Is. The adder adds the EXOR results from the 32 EXOR circuits and outputs the result. Accordingly, the 32 EXOR circuits and the adder cooperate to function as an arithmetic unit. The EXOR circuit and the adder are realized by a logic circuit.
[0054]
Furthermore, since all of the matched filters 2b to 2h in the measurement unit 1 are the same as or have the same function as the matched filter 2a, redundant description is omitted.
In addition, the divided matched filter 13 includes a full adder 12. The full adder 12 adds all the calculation results output from the matched filters 2a to 2h and outputs the full addition result. The full adder 12 is realized by a logic circuit.
[0055]
As a result, the received data # 1 is input to the matched filter 2a, despread, and the correlation value is input to the full adder 12. Further, the bit string of the reception data # 1 input to the matched filter 2a sequentially shifts the shift register including the first taps 1 to 32.
Subsequently, the selector 3b receives the received data # 2 and the output from the matched filter 2a, selects one of them and outputs the selected data (the received data # 2 or the output from the matched filter 2a). is there. For example, as shown in FIG. 5 (a) or 5 (b), the selector 3b also receives the coupling control signal. When the logic of the coupling control signal is 1, the received data # 2 is output, and 0 In this case, the tap 1 of the matched filter 2a is output. The output selection data is input to the matched filter 2b.
[0056]
Thus, when the logic of the coupling control signal is 1, the selectors 3a and 3b select the received data # 1 and # 2 and input them to the matched filters 2a and 2b, respectively, and independently despread for different calls. Is done. That is, the matched filters 2 a and 2 b despread the channels 1 and 2 in parallel, and the calculation result is input to the full adder 12.
[0057]
When the logic of the coupling control signal is 0, the selectors 3a and 3b select the reception data # 0 and the output of the matched filter 2a, respectively. That is, the matched filters 2a and 2b function as a 64-tap correlator. Also at this time, the despread calculation result is input to the full adder 12.
In the following description, in order to distinguish the form of the number of tap stages when the divided matched filter 13 is divided / combined, for example, 32 tap × 8 parallel is called a 32-tap configuration, and 256 taps × 1. The book may be referred to as a 256 tap configuration.
[0058]
In this way, the matched filters 2a and 2b are separated or combined by the combination control signal.
Similarly, each of the selectors 3c to 3h receives the received data # 3 to # 8 and the output from the matched filters 2b to 2g, and selects one of these to select the selected data (received data # 3 to # 8). Or output from the matched filters 2b to 2g). For example, as shown in FIG. 5A or FIG. 5B, these selectors 3c to 3h also receive a coupling control signal, and when the logic of the coupling control signal is 1, received data # 3 to # 8. When the value is 0, the first tap 31 of the matched filter 2b to the first tap 31 of the matched filter 2g are output. The output selection data is input to an averaging processing unit 4 described later.
[0059]
Thereby, when the logic of the coupling control signal is 1, the selectors 3a to 3h select the received data # 1 to # 8, respectively, and these received data # 1 to # 8 are respectively matched with the matched filters 2a to # 8. It is input to 2h and despread in parallel for eight different calls.
When the logic of the coupling control signal is 0, the selectors 3a to 3h select the output of the reception data # 0 and the matched filters 2a to 2g, respectively. Therefore, the divided matched filter 13 has a 256 tap configuration. That is, one block of the matched filter 2a is formed by 32 taps 1 to 32 and one adder, and eight blocks are connected in cascade, so that the divided matched filter 13 has 256 taps. It becomes a configuration.
[0060]
Therefore, the measurement unit 1 includes one of the received data # 1 to # 8 and one of the eight received data # 1 to # 8 resulting from each of the eight types of code-multiplexed RF signals, for example. Selector 3a (or 3b-3h) for selecting and holding selected data (received data # 1 to # 8 or received data # 0) by selecting one of the same copy data, and selected data output from selector 3a An 8-stage block having a unit matched filter 2a (or 2b to 2h) for delaying and outputting the selected data is provided while multiplying the replica code and adding and outputting the multiplication result, and in the preceding block The eight blocks are connected in multiple stages so that the selection data delayed in this manner is input to the selector 3b (or selectors 3c to 3h).
[0061]
The measurement unit 1 also includes eight types of received data # 1 other than those in which the 8-stage selectors 3a to 3h are input to a plurality of blocks up to the previous stage among the eight types of received data # 1 to # 8. One of .about. # 8 and selection data delayed in the preceding block are selected and output, and the respective reception levels of the RF signals are output.
[0062]
The delay amount / path detection unit 8 outputs the path timing at which the RF signal arrives based on the reception level output from the measurement unit 1, and the eight types of unit matched filters 2 a to 2 h are output to the measurement unit 1. A combination control signal relating to the division / combination is output.
For example, when focusing on the matched filter 2c and the selector 3c, the selector 3c includes two blocks (a block made up of the selector 3a and the matched filter 2a, a selector 3b, a matched filter, and so on) of received data # 1 to # 8. Received data # 3 other than the received data # 1 and # 2 input to the block 2b) and selection data (matched filter 2b of the matched filter 2b) delayed in the preceding block (block consisting of the selector 3b and the matched filter 2b) Output) is selected and output.
[0063]
As described above, the measurement unit 1 switches to either the 256 tap configuration or the 32 tap configuration according to the call reception state based on the coupling control signal, and acquires the delay profile.
As a result, even when the number of calls increases, the base station 22 can shorten the cycle of the path timing notification.
[0064]
Further, in FIG. 3, the outputs of the matched filters 2 a to 2 h are respectively input to the average calculation unit 11. Specifically, this output corresponds to amplitude data. Then, the average calculation unit 11 calculates the delay profile value output from each of the blocks in which 1, 2, 4 and 8 unit matched filters 2a to 2h are combined among the 8 unit matched filters 2a to 2h. An average value is output on average, and includes eight selectors 9 and eight averaging processing units 4 connected to each of the eight selectors 9. All outputs from the matched filters 2 a to 2 h are input to the average calculation unit 11. Further, the average calculation unit 11 averages only correlation data for received data and a replica code, and outputs the average value.
[0065]
FIG. 6 is a diagram for explaining the averaging process according to the first embodiment of the present invention. The average calculation unit 11 shown in FIG. 6 includes a selector 9 and an averaging processing unit 4. Here, the selector 9 selects and outputs one of the output (amplitude data) of the matched filter 2a and the output (amplitude data) of the full adder 12, and this function is realized by a logic circuit, for example. The
[0066]
The averaging processing unit 4 performs averaging processing by cyclic addition. The power conversion unit 4a outputs the square data by squaring the amplitude data, and the square output from the power conversion unit 4a. An adder 4b that cumulatively adds data and a dual-port memory (hereinafter sometimes abbreviated as a memory) 4c that stores the added value in the adder 4b are configured. Here, the power conversion unit 4a, the adder 4b, and the memory 4c are realized by, for example, a square circuit, a logic circuit, and a RAM (Random Access Memory), respectively.
[0067]
In addition, since what has the same code | symbol as what was shown in this FIG. 6 and mentioned above has the same thing or the same function, further description is abbreviate | omitted.
As a result, the amplitude data from the full adder 12 (see FIG. 3) is squared by the averaging processing unit 4 and output. That is, first, the amplitude data input from the selector 9 is squared by the power conversion unit 4a, and the squared square data is directly written into the memory 4c via the adder 4b. Next, the square data squared by the power conversion unit 4a is added to the first square data stored in the memory 4c by the adder 4b, and the added value is written to the memory 4c. Similarly, the amplitude data input to the selector 9 is squared, and the square data is cumulatively added to the data written in the memory 4c. Therefore, the average value of the square data is calculated.
[0068]
Next, this averaging process will be described in further detail with reference to FIGS.
FIG. 7 is a diagram showing a format example of received data according to the first embodiment of the present invention. The slot row 14 shown in FIG. 7 has a plurality of slots 1 to n (n is a preset natural number of 2 or more), and each slot 1 to n has a pilot symbol. Then, the averaging processing unit 4 in the base station 22 cumulatively adds the delay profiles for each of the slots 1 to n, finally calculates one delay profile, and the delay obtained by the addition The path is detected based on the profile.
[0069]
FIGS. 8A to 8C are diagrams each showing a reception level in the averaging processing according to the first embodiment of the present invention, where the horizontal axis indicates the number of the added slot, and the vertical axis indicates the correlation value level. Is displayed. Here, the correlation value level corresponds to a delay profile.
The correlation value level shown in FIG. 8A is averaged using only slot 1, and the peak value is obtained as, for example, “3FF” in hexadecimal by the matched filters 2a to 2h. Since this value can be expressed as “11 1111 1111” in binary, it is output as a 10-bit peak value.
[0070]
By the way, the delay profile using only slot 1 has errors such as instantaneous fluctuations. For this reason, the base station 22 cumulatively adds a plurality of slots in order to obtain a more accurate value.
The correlation value level shown in FIG. 8B is obtained by adding the slots 1 and 2. Here, for example, the averaging processing unit 4 obtains the peak value “3FF” for the slot 1, obtains the peak value “3FF” for the slot 2, and calculates the peak value of the slot 1 and the peak value of the slot 2. When the full addition is performed, a carry occurs in the result of the full addition, and the number of bits for displaying the peak value becomes 11 bits.
[0071]
Further, the correlation value level shown in FIG. 8C is obtained by performing full addition for all of slots 1 to n, and the addition result is represented by (10 + n) bits. As a result, the delay profiles from the plurality of slots 1 to n are averaged, and a large peak value appears larger, and the error variation is canceled.
Therefore, the measuring unit 1 can detect a pulse and measure a delay profile where a peak value occurs.
[0072]
As described above, the base station 22 can receive the RF signals from the plurality of mobile stations 21, obtain a delay profile for these RF signals with high accuracy, and can separate the mobile stations 21.
Next, the delay amount / path detection unit 8 shown in FIG. 3 outputs the path timing at which the RF signal arrives based on the reception level output from the measurement unit 1, and eight matched values for the measurement unit 1. A combination control signal related to the division / combination of the filters 2a to 2h is output, and includes a path level determination unit group 5a including eight path level determination units (path level determination circuits) 5, and eight path detection units. (Path detection) 6 and a coupling control unit (MF coupling control) 7 are provided.
[0073]
Here, the path level determination unit 5 outputs a coupling control signal based on the average value output from the average calculation unit 11 and a preset threshold value. This function is realized by hardware and software. This threshold is determined in consideration of various parameters in the system 20 in, for example, experiments and simulations, and is set in advance.
[0074]
Thereby, the base station 22 measures the delay profile based on the specification of the system 20.
FIGS. 9A to 9C are diagrams for explaining the path timing according to the first embodiment of the present invention. The waveform shown in FIG. 9A schematically shows the relationship between time and reception level in the base station 22. The peak of the reception level attached with 1 shown in FIG. 9A represents a direct wave of the RF signal transmitted by one mobile station 21, and the peaks attached with 2, 3 Each represents a delayed wave from the mobile station 21.
[0075]
Then, the path level determination unit 5 (see FIG. 3) outputs a signal that shifts to the 256-tap configuration to the measurement unit 1 when the received path level decreases based on the threshold value. Yes. As a result, an optimum threshold can be set according to the traffic status and physical status of the system 20 without increasing the circuit scale. Also, the plurality of path level determination units 5 are all the same, and when the divided matched filter 13 has a 256-tap configuration, the signal from the matched filter 2h is determined. Further, when the divided matched filter 13 has a 32-tap configuration, the signals from each of the matched filters 2a to 2h are determined separately.
[0076]
The path detection unit 6 detects and outputs path timing for at least each channel. This function is realized by hardware and software. That is, the path detection unit 6 detects path timing for each of the reception data # 1 to # 8.
Each pulse shown in FIG. 9B represents an example of a path timing signal output from the delay amount / path detection unit 8. That is, the arrival of the direct wave (peak 1) and the arrival of the delayed wave (peaks 2 and 3) are respectively input from the delay amount / path detection unit 8 to the code generation unit 50g. .
[0077]
Further, the coupling control unit 7 controls switching / coupling of the eight matched filters 2 a to 2 h based on the coupling control signal output from the delay amount / path detection unit 8. The function of the coupling control unit 7 is realized by hardware and software.
FIG. 9C shows an example of code generation timing of the code generator 50g. Then, by inputting the path timing signal from the delay amount / path detection unit 8, the code generation unit 50g can know the head of the path of the direct wave (peak 1). In other words, the path timing signal represents the first bit of the replica code, and the code generator 50g starts to generate the first bit of the replica code when the path timing signal is input.
[0078]
Therefore, the measurement unit 1 is provided with code generation units 50g and 50j that generate replica codes, and the delay amount / path detection unit 8 is configured to input a coupling control signal to the code generation units 50g and 50j. It will be. As a result, the base station 22 can follow the movement of the high-speed mobile station 21 and can accurately detect the path timing even when the divided matched filter 13 is in parallel.
[0079]
More specifically, the coupling control unit 7 included in the delay amount / path detection unit 8 switches, for example, three types of operation modes defined based on the number of tap stages to which the eight matched filters 2a to 2h are connected. , Switching control. The three types of operation modes mean a case where a new call is generated, a case where the reception state is stable, and a case where the correlation level of the delay profile is lowered.
[0080]
That is, the coupling control unit 7 switches the operation mode in any of these three types. Therefore, by providing one divided matched filter 13, the receiving device 25 can measure a delay profile for a plurality of channels without using the divided matched filter 13.
Specifically, the combination control unit 7 selects three types of operation modes, for example, a block in which 1, 2, 4, and 8 matched filters 2a to 2h out of 8 unit matched filters 2a to 2h are combined. Switching control is performed in consideration of the number of blocks representing the number.
[0081]
In other words, the coupling control unit 7 has at least three types of operation modes of a 32-tap configuration (32 taps × 8 parallel), a 256-tap configuration (256 taps × 1 parallel), and a 128-tap configuration (128 taps × 2 parallel). Can be switched. Thereby, the delay profiles of a plurality of calls can be measured using one matched filter without degrading the quality of received data.
[0082]
Further, the combination control unit 7 gives priority to each of the eight types of calls. Specifically, priority is given based on at least three cases: when a newly added call occurs, when the delay profile peak value of any call falls below a predetermined threshold, and during normal operation. The order is decided. Thereby, an appropriate operation change is possible.
[0083]
Then, the operation mode of the divided matched filter 13 shown in FIG. The block composed of the selector 3a and the matched filter 2a operates individually according to the parallel number or operates as a 256 tap configuration. Specifically, the operation mode is switched as described below.
[0084]
In the CDMA reception method of the present invention, first, the divided matched filter 13 despreads at least one of, for example, eight types of RF signals that have been code-multiplexed, and one of the eight types of RF signals. Process data for a specific RF signal (any of eight types) is output (despreading step).
Next, the measurement unit 1 measures the delay profile of the processing data output in the despreading step, for example, for 256 × (1 / N) seconds (measurement step).
[0085]
Subsequently, the path level determination unit 5 compares the reception level of the specific RF signal with a preset threshold value based on the delay profile obtained by measurement (comparison step).
Then, the coupling control unit 7 changes the time interval of 256 × (1 / N) seconds based on the comparison in the comparison step (operation mode change step).
[0086]
As described above, when the reception condition is good, the delay profile can be measured for each of the eight calls with a 32-tap configuration. In addition, when the reception state deteriorates as described above, the delay profile is measured for one call by the 256 tap configuration, so that measurement with higher accuracy is possible.
Furthermore, in the CDMA reception method of the present invention, first, the divided matched filter 13 despreads at least one of, for example, eight types of RF signals that are code-multiplexed, and one of the eight types of RF signals. Process data for one specific RF signal is output (despreading step).
[0087]
Next, the measurement unit 1 measures the delay profile of the processing data output in the despreading step for 256 × (1 / N) seconds (measurement step).
Subsequently, the path level determination unit 5 outputs the reception level of the specific RF signal based on the delay profile obtained by measurement (reception level output step).
The combination control unit 7 switches the division / combination of the eight unit matched filters 2a to 2h based on the reception level (switching step).
[0088]
As described above, by providing one divided matched filter 13, it is possible to measure the delay profile of eight calls without reusing them. In addition, in this way, the delay profiles of eight channels can be individually measured using one divided matched filter 13 without degrading the quality of received data.
The reception method of the CDMA system of the present invention configured as described above will be described in detail with reference to FIGS.
[0089]
First, the mobile station 21 transmits data to the base station 22, and the receiving device 25 in the base station 22 processes the received RF signal. Here, the coupling control unit 7 switches the 256 tap configuration or the 32 tap configuration in the received operation mode. Specifically, the connection control unit 7 switches the tap configuration in each of the following operation modes (1-1) to (1-3).
[0090]
(1-1) When a newly added call occurs
(1-2) When the reception state is stable
(1-3) When the correlation level of the delay profile decreases during the call
Here, when the operation mode (1-3) is entered, the operation is switched by the path level determination unit 5. Based on a preset threshold value, the divided matched filter 13 shifts to a 256-tap configuration when the path level decreases.
[0091]
Hereinafter, each of these operation modes will be described in detail.
(1-1) When a newly added call occurs
The measuring unit 1 measures the delay profile with a 256 tap configuration.
FIG. 10 is a configuration diagram of the matched filter when a new call is generated according to the first embodiment of the present invention. Further, what is shown in FIG. 10 and has the same reference numeral as that described above has the same or similar function, and therefore further explanation is omitted.
[0092]
Here, when the measurement unit 1 newly starts receiving channel 1, the coupling control unit 7 acquires delay profile data so that the 32-tap divided matched filter 13 is connected in an 8-stage cascade. .
FIG. 11 is a diagram showing a time width of a delay profile when a new call is generated according to the first embodiment of the present invention. Here, when the sampling rate of the A / D conversion of the received data is N [MHz], the time width of the delay profile to be measured is set to 256 × (1 / N) seconds.
[0093]
(1-2) When the communication state is stable
When the first pass timing notification is completed, the measurement unit 1 measures the delay profile using one of the 32-tap configurations.
FIG. 12 is a configuration diagram of the matched filter at the time of stable communication according to the first embodiment of the present invention, and has a 32-tap configuration. Moreover, what is shown in this FIG. 12 and has the same code | symbol as what was mentioned above has the same thing or the same function, Therefore Further description is abbreviate | omitted.
[0094]
FIG. 13 is a diagram showing the time width of the delay profile during stable communication according to the first embodiment of the present invention. The time width of the measured delay profile is 256 × (1 / N) seconds. The darkly colored portion shown in FIG. 13 is a time that is not used, and the time that is used is only 32 × (1 / N) seconds. Therefore, the time width during which the measurement unit 1 measures the delay profile is shortened.
[0095]
(1-3) When the correlation level of the delay profile is lowered during a call, the coupling control unit 7 again sets the split-type matched filter 13 having a 32-tap configuration to a 256-tap configuration.
This is because the path level always varies. In other words, the propagation path may increase fading due to increased interference or increased vehicle speed. For this reason, in the path level determination, when the data value of the measured delay profile becomes smaller than a preset threshold value, the coupling control unit 7 again sets the divided matched filter 13 having the 32-tap configuration to 256 taps. In addition, the time width of the delay profile for measurement is expanded.
[0096]
FIG. 14 is a diagram showing the time width of the delay profile when the correlation value of the delay profile is lowered according to the first embodiment of the present invention. The time width of the measured delay profile is 256 × (1 / N) seconds. The portion other than the dark color portion shown in FIG. 14 is used time, which is only 32 × (1 / N) seconds. Therefore, when the peak value of the measured delay profile falls below the threshold level, the time width is expanded.
[0097]
FIG. 15 is a diagram showing a time width of the delay profile when the peak value of the delay profile according to the first embodiment of the present invention falls below a threshold value. And the measurement part 1 continues measuring a delay profile in this state until it exceeds a threshold value again.
FIG. 16 is a diagram showing the time width of the delay profile when the peak value of the delay profile according to the first embodiment of the present invention exceeds the threshold value. The portion other than the dark color portion shown in FIG. 16 is used time, which is only 32 × (1 / N) seconds. When a delay profile value exceeding the predetermined threshold shown in FIG. 16 is detected, the divided matched filter 13 returns to the 32-tap configuration again.
[0098]
As described above, since the coupling control unit 7 changes the connection form of the divided matched filter 13 according to the delay profile, efficient reception is possible.
Further, when receiving and processing a plurality of calls, the combination control unit 7 determines the priority order of the plurality of calls according to the cases shown in the following (2-1) to (2-3).
(2-1) When a newly added call occurs
The divided matched filter 13 is changed to a 256 tap configuration.
[0099]
(2-2) When the delay profile peak value of any channel falls below a predetermined threshold
The divided matched filter 13 is changed to a 256 tap configuration.
(2-3) Normal operation
The divided matched filter 13 is changed to a 32-tap configuration.
[0100]
For example, when the measurement unit 1 performs reception processing for eight channels in parallel, one of the 32-tap matched filters 2a to 2h is assigned to each channel one by one.
Therefore, the measurement unit 1 does not wait for the acquisition of the delay profile, and the cycle of the path timing notification is constant. As a result, it is possible to receive a plurality of channels without increasing the circuit scale.
[0101]
Further, when the peak value of the delay profile of any call falls below a predetermined threshold, the combination control unit 7 combines the eight 32 taps assigned to each channel again, and the measurement unit 1 focuses on only calls whose peak value is below. In this case, for other calls, use of the matched filters 2a to 2h is restricted, so that the cycle of the path timing notification becomes longer. For this reason, for newly added calls, the use of the matched filters 2a to 2h is assigned with the highest priority, and the path timing is notified as soon as possible.
[0102]
FIGS. 17A and 17B are diagrams for explaining coupling / separation of the matched filter according to the first embodiment of the present invention. As shown in FIG. 17A, when the peak value of each call exceeds a preset threshold value, the combination control unit 7 assigns 32-tap matched filters 2a to 2h to each call. . In this case, the cycle of the path timing notification for each call is not affected by the reception state of other calls and is always a constant cycle.
[0103]
Also, as shown in FIG. 17B, for example, when the peak value of channel 3 falls below a preset threshold value, the coupling control unit 7 assigns the divided-type matched 32-bit configuration assigned to each call. The filter 13 is canceled and the configuration is changed to the 256 tap configuration, whereby the measurement unit 1 mainly determines the delay profile of the channel 3.
In this way, the divided matched filter 13 can be divided into a plurality of portions, and when the call state is stable such that the peak value of the delay profile exceeds the threshold value, the delay profile measurement of each call is performed. The period is always a constant period.
[0104]
In addition, since the cycle of the path timing notification is constant, it is possible to follow the moving speed of the mobile station. Furthermore, by making the matched filter a split type, it is possible to shorten the cycle of the path timing notification even if the number of calls increases.
Furthermore, when there is a new call or a decrease in the peak value level of the delay profile as described above, as a regular process, a 32 tap × 8 parallel configuration is connected in cascade to form a 256 tap configuration. Since the delay profile can be measured, processing according to the reception status can be performed, and processing can be performed without increasing the circuit scale.
[0105]
(A1) Description of Modification of First Embodiment of the Present Invention
FIG. 18 is a diagram illustrating a main part of the receiving device of the mobile station 21 according to the modification of the first embodiment of the present invention. A CDMA mobile receiver (CDMA receiver, hereinafter abbreviated as receiver) 25a shown in FIG. 18 is provided in the mobile station 21 and receives a code-multiplexed RF signal. The RF unit 50-1, the despreading unit 50f, the code generation units 50g and 50j, the delay profile measurement unit (measurement unit) 1, the delay amount / path detection unit (delay amount output unit) 8, Is configured.
[0106]
Here, the receiving device 25a differs from the receiving device 25 shown in FIG. 2 in that there is only one RF unit 50-1. For example, eight types of code-multiplexed RF signals are input via one antenna 50a, and the eight types of RF signals are input to the despreading processing unit 50f and the measurement unit 1, respectively, and are different. The code is multiplied and processed.
[0107]
In other words, a plurality of channels obtained by the antenna 50a are despread using different codes and separated.
In addition, since what has the same code | symbol as what was shown in this FIG. 18 and mentioned above has the same thing or the same function, further description is abbreviate | omitted.
Also in the modified example of the first embodiment, the RF signal 50-1 of the RF unit 50-1 receives the code-multiplexed RF signal, and eight types of calls are received in a lump, and the band-pass filter 50b and the low-noise amplifier are received. 50c, frequency converter 50d and A / D converter 50e are converted into digital data, respectively. Further, each of the despreading processing unit 50f and the measurement unit 1 performs reception processing for each call individually.
[0108]
With such a configuration, the measurement unit 1 of the reception device 25a measures the delay profile of the received wave, and estimates the path timing of the incoming received wave based on the measurement result. Here, the divided matched filter 13 and the path level determination unit 5 respectively compare a threshold value of a preset path level with the peak of the detected correlation value, and send the value to the delay amount / path detection unit 8. Enter. Then, the delay amount / path detection unit 8 notifies the despreading processing unit 50f of the delay amount based on the path timing, and the combination control unit 7 selects the operation mode of 32 taps × 8 blocks or 256 taps × 1. The switching process is performed.
[0109]
Further, the combination control unit 7 controls the combination / division of the division type matched filter 13 and cascades 32 taps × 8 parallels when there is a new call or a decrease in the peak value level of the delay profile. , And change to a 256 tap configuration to measure the delay profile.
Thus, the receiving device 25a can follow the moving speed of the mobile station 21. Further, even if the number of calls increases, the cycle of path timing notification can be shortened.
[0110]
In this way, processing according to the reception status can be performed, and processing can be performed without increasing the circuit scale.
(B) Other
The present invention is not limited to the above-described embodiments and modifications thereof, and various modifications can be made without departing from the spirit of the present invention.
[0111]
The receiving device 25 (25a) of the present invention is not limited to the CDMA system, and can be applied when another system is used.
As the above spreading code, another code can be used instead of the PN code.
The RF unit has eight channels for simplicity of explanation, but this number can be 16 or more, or can be changed according to the number of subscribers.
[0112]
The coupling control unit 7 is provided in the delay amount / path detection unit 8, but can be provided independently outside the delay amount / path detection unit 8, or can be provided inside the delay profile measurement unit 1. It can also be provided. Even if such a modified embodiment is used, the superiority of the present invention is not impaired.
Although the example of the coupling control signal is shown as 1 bit, it can be composed of a plurality of bits so as to transmit additional information. The enable signal can also be displayed by a plurality of bits.
[0113]
The above threshold value is set in advance, but the receiving device 25 (25a) can also obtain this threshold value by adaptively changing it during reception or calculating it according to the reception status.
(1) and (2) shown in FIG. 1 mean that the mobile station 21 in communication moves in the cell 61 (or sector 62) at a high speed and moves away from the base station 22. Even in this case, the base station 22 can follow the high-speed movement of the mobile station 21.
[0114]
4, the matched filters 2b to 2h are the same as or similar to the configuration of the matched filter 2a shown in FIG.
In FIG. 9A, t₁, T₂, T_ThreeIndicates the times when the peaks 1, 2 and 3 appear, respectively.
In the measurement unit 1 shown in FIG. 10, the operating signal line is indicated by a solid line, the non-operating signal line (virtual line) is indicated by a two-dot chain line, and the coupling control unit 7 and the selectors 3a to 3h A dotted line between the lines indicates a control line. Here, the selector 3a selects the reception data # 0 and the reception data # 1, and the data is shifted through the matched filters 2a to 2h. The calculation results output from each of the matched filters 2 a to 2 h are fully added by the full adder 12, and the full addition result is input to the selector 9. Further, a channel 1 path timing notification is output from the path detection unit 6 via the averaging processing unit 4 and the path level determination unit 5. In addition, a coupling control signal is output from the path level determination unit 5 to the coupling control unit 7, and the coupling control unit 7 controls the selectors 3a to 3h.
[0115]
11, 13, 14, 15, and 16 represent seconds.
In the measurement unit 1 shown in FIG. 12, the operating signal line is indicated by a solid line, the non-operating signal line (virtual line) is indicated by a two-dot chain line, and the coupling control unit 7 and the selectors 3a to 3h A dotted line between the lines indicates a control line. Here, the received data # 8 is input to the matched filter 2h, passes through the matched filter 2h, the selector 9, the averaging processing unit 4 and the path level determination unit 5, respectively, and the channel detection unit 6 notifies the channel 1 path timing. Is output. In addition, a coupling control signal is output from the path level determination unit 5 to the coupling control unit 7, and the coupling control unit 7 controls the selectors 3a to 3h.
[0116]
Ch in FIG. 17 means a channel.
(C) Appendix
(Supplementary note 1) One of received data resulting from each of a plurality of code-multiplexed radio frequency signals and one of a plurality of received data and the same copy data are selected and held and output. A delay profile measuring unit that has a plurality of unit matched filters that multiply the selected data and the replica code and add and output the multiplication result, and that outputs each reception level of the radio signal, and the delay profile Based on the reception level output from the measurement unit, the path timing at which the radio signal arrives is output, and a coupling control signal related to division / combination of the plurality of unit matched filters is output to the delay profile measurement unit. A CDMA receiving apparatus comprising a delay amount output unit.
[0117]
(Appendix 2) The delay amount output unit
The CDMA system reception according to appendix 1, wherein the switching control is performed by switching a plurality of operation modes defined based on the number of tap stages to which the plurality of unit matched filters are connected. apparatus.
(Supplementary Note 3) Each of the plurality of unit matched filters of the delay profile measuring unit is
A finite state holding unit equal to the number of taps holding received data;
A number of latch units equal to the number of taps capable of outputting a replica code;
The CDMA system according to appendix 1, characterized by comprising an arithmetic unit that multiplies the output from the finite state holding unit and the output from the latch unit, adds the multiplication results, and outputs the result. Receiver.
[0118]
(Supplementary Note 4) The delay amount output unit
The plurality of operation modes are configured to perform switching control in consideration of the number of blocks representing the number of blocks to which a predetermined number of unit matched filters of the plurality of unit matched filters are combined. The CDMA receiver according to appendix 1.
[0119]
(Supplementary Note 5) The delay amount output unit
The CDMA system according to appendix 4, wherein at least three types of operation modes can be switched between a 32-tap configuration of 8 blocks, a 256-tap configuration of 1 block, and a 128-tap configuration of 2 blocks. Receiver.
(Supplementary Note 6) The delay profile measurement unit includes a replica code generation unit that generates the replica code.
The CDMA receiving apparatus according to appendix 1, wherein the delay amount output unit is configured to input the coupling control signal to the replica code generation unit.
[0120]
(Appendix 7) The delay amount output unit
The present invention is characterized in that the operation mode is switched when at least one of a new call occurs, a reception state is stable, and a correlation level of a delay profile is lowered. CDMA receiver according to appendix 1.
[0121]
(Supplementary Note 8) The delay profile measurement unit
An average calculator that averages the delay profile values output from each of the blocks to which a predetermined number of unit matched filters of the plurality of unit matched filters are combined, and outputs an average value;
The delay amount output unit
The CDMA system according to claim 1, further comprising a path level determination unit that outputs the coupling control signal based on the average value output from the average calculation unit and a predetermined threshold value. Receiver.
[0122]
(Supplementary Note 9) The delay amount output unit further includes:
9. The CDMA receiving apparatus according to appendix 8, characterized by comprising a path detection unit that detects and outputs path timing for at least each channel.
(Supplementary Note 10) One of received data caused by each of a plurality of code-multiplexed radio frequency signals and one of a plurality of received data and the same copy data are selected and held and output. And a unit matched filter that multiplies the selection data output from the selector and the replica code, adds the multiplication result and outputs the result, and outputs the selection data with delay. In addition, the plurality of blocks are connected in multiple stages so that the selection data delayed in the preceding block is input to the selector.
The selector of the plurality of blocks includes one of a plurality of received data other than those input to the plurality of blocks up to the previous stage among the plurality of received data, and the selection data delayed in the block of the previous stage And a delay profile measurement unit configured to output each reception level of the radio signal,
Based on the reception level output from the delay profile measuring unit, the arrival timing of the radio signal is output, and a combined control signal for dividing / combining the plurality of unit matched filters is output to the delay profile measuring unit. A CDMA receiving device, characterized by comprising a delay amount output unit for outputting.
[0123]
(Supplementary Note 11) The delay amount output unit
The priority of multiple calls is based on at least three types of cases: when a newly added call occurs, when the delay profile peak value of any channel falls below a predetermined threshold, and during normal operation The CDMA receiving device according to appendix 1, wherein the receiving device is configured to be attached to the CDMA system.
[0124]
(Supplementary Note 12) A despreading step of despreading at least one of a plurality of code-multiplexed radio signals and outputting processing data for one specific radio signal of the plurality of radio signals;
A measurement step of measuring a delay profile of the processing data output in the despreading step for a predetermined time;
A comparison step of comparing a reception level of the specific radio signal with a predetermined threshold based on the delay profile obtained by the measurement;
A CDMA reception method, comprising: an operation mode change step for changing the predetermined time interval based on the comparison in the comparison step.
[0125]
(Supplementary Note 13) A despreading step of despreading at least one of a plurality of code-multiplexed radio signals and outputting processing data for one specific radio signal of the plurality of radio signals;
A measurement step of measuring a delay profile of the processing data output in the despreading step for a predetermined time;
A reception level output step of outputting the reception level of the specific radio signal based on the delay profile obtained by the measurement;
A CDMA reception method comprising: a switching step for switching division / combination of a plurality of unit matched filters based on the reception level.
[0126]
【The invention's effect】
  As described in detail above, the CDMA receiver of the present invention.PlacementAnd CDMA receptionTo the lawAccording to this, the following effects or advantages can be obtained.
  (1) The CDMA receiver of the present invention has a plurality of unit matched filters that hold and output selection data, multiply the selection data by a replica code, and add and output the multiplication result.frequencyBased on the delay profile measurement unit that outputs each reception level of the signal and the reception level output from the delay profile measurement unit,wirelessfrequencyOutputs the timing of signal arrival and delay profile measurement unitControl the selection action atMultiple unit matched filterswhileofControl connection statusThe delay amount output sectionYeahTherefore, when the call state is stable, the delay profile measurement period of each call is always a constant period. In addition, since the cycle of the path timing notification is constant, it is possible to follow the moving speed of the mobile station. Furthermore, even if the number of channels increases, the path timing notification cycle can be shortened.The
[0127]
  (2) The delay amount output unitSpecified based on the number of tap stages to which multiple unit matched filters are connectedThe plurality of operation modes may be configured to be switched and controlled in consideration of the number of blocks representing the number of blocks combined with a predetermined number of unit matched filters among the plurality of unit matched filters. When there is a new call addition or a decrease in the peak value level of the delay profile, as an irregular process, for example, a unit matched filter is connected in cascade with 32 taps × 8 parallels, or by a 256 tap configuration. Since the delay profile can be measured, processing can be performed according to the reception status, and processing can be performed without increasing the circuit scale.The
[0128]
  (3) When the delay amount output unit is at least one of a case where a new call occurs, a case where the reception state is stable, and a case where the correlation level of the delay profile is lowered,SaidIt may be configured to switch the operation mode, and in this way, reception processing of a plurality of channels can be performed without increasing the circuit scale.The
[0129]
  (4) According to the CDMA receiving apparatus of the present invention, the selector, the selection data output from the selector, and the replica code are multiplied and the multiplication result is added and output, and the selection data is delayed and output. A plurality of blocks having a unit matched filter are provided, and the selection data delayed in the preceding block isIn the next blockThe multiple blocks are connected in multiple stages so that they are input to the selector.InThe selector selects and outputs one of a plurality of received data other than those input to a plurality of blocks up to the preceding stage and the selection data delayed in the preceding block. And wirelessfrequencyA delay profile measurement unit configured to output each reception level of the signal is provided, and based on the reception level output from the delay profile measurement unit.,wirelessfrequencyOutput the path timing when the signal arrives,Control selector selection in the multiple blocksMultiple unit matched filterswhileofControl connection statusThe delay timing output section is configured to reduce the path timing notification cycle even if the number of channels increases.The
[0130]
  (5) According to the CDMA reception method of the present invention, a plurality of code-multiplexed radiosfrequencyMultiple radios by despreading at least one of the signalsfrequencySpecific radio of one of the signalsfrequencyA despreading step for outputting processed data on the signal, a measuring step for measuring a delay profile of the processed data output in the despreading step for a predetermined time, and a specific radio based on the delay profile obtained by the measurementfrequencyA reception level output step for outputting the reception level of the signal, and a plurality of unit matched filters based on the reception levelwhileofConnection statusSince the delay profile is measured with a separate tap configuration when the reception status is good and when it deteriorates, more accurate measurement is possible.The
[0131]
(6) The delay amount output unit may be configured to perform switching control by switching a plurality of operation modes defined based on the number of tap stages to which a plurality of unit matched filters are connected. For example, by providing one division type matched filter, it is possible to measure the delay profile for a plurality of channels without reusing them.
[0132]
(7) Each of the plurality of unit matched filters of the delay profile measuring unit includes a finite state holding unit equal to the number of taps holding received data, a number of latch units equal to the number of taps capable of outputting a replica code, and a finite state. An arithmetic unit that multiplies the output from the holding unit and the output from the latch unit, adds the multiplication results, and outputs the result may be configured. As described above, it is possible to adaptively combine / divide with other unit matched filters to process received data efficiently.
[0133]
(8) The delay amount output unit may be configured to be able to switch at least three types of operation modes of a 32-tap configuration, a 256-tap configuration, and a 128-tap configuration, and in this way, the quality of received data is reduced. Without this, the delay profiles of a plurality of channels can be measured using one matched filter.
(9) The delay profile measurement unit may include a replica code generation unit that generates a replica code, and the delay amount output unit may be configured to input a coupling control signal to the replica code generation unit. In this way, the base station can follow the movement of the high-speed mobile station.
[0134]
(10) An average calculation unit that outputs a mean value by averaging a delay profile value output from each of blocks in which a predetermined number of unit matched filters are combined among a plurality of unit matched filters. In addition, the delay amount output unit may be configured to include a path level determination unit that outputs a coupling control signal based on an average value output from the average calculation unit and a predetermined threshold, as described above. In this case, an optimum threshold value can be set according to the traffic status and physical status of the system without increasing the circuit scale.
[0135]
(11) The delay amount output unit may further include at least a path detection unit that detects and outputs a path timing for each channel. In this way, the unit matched filters are individually parallelized. Even when processing in a state, the path timing can be detected.
(12) When the delay amount output unit gives priority to a plurality of calls, a newly added call occurs, a delay profile peak value of any channel falls below a predetermined threshold, and a normal operation It may be configured to give based on at least three kinds of cases, and in this way, an appropriate operation change can be made.
[0136]
(13) A despreading step that despreads at least one of the plurality of code-multiplexed radio signals and outputs processing data for one specific radio signal of the plurality of radio signals, and a despreading step A measurement step for measuring a delay profile of output processing data for a predetermined time, a comparison step for comparing a reception level of a specific radio signal with a predetermined threshold based on the delay profile obtained by the measurement, and a comparison in the comparison step And the operation mode changing step for changing the interval of a predetermined time based on the above. When the reception condition is good, for example, the unit matched filter of 32 taps is set to 8 parallels, and the delay is set for each of the 8 channels. Profiles can be measured.
[0137]
(14) A despreading step of despreading at least one of the plurality of code-multiplexed radio signals and outputting processing data for one specific radio signal of the plurality of radio signals, and a despreading step A measurement step for measuring a delay profile of the output processing data for a predetermined time, a reception level output step for outputting a reception level of a specific radio signal based on the delay profile obtained by the measurement, and a plurality of units based on the reception level Since it is configured with a switching step for switching the division / combination of the matched filter, when the reception situation deteriorates, for example, a 256-tap configuration can be used to measure the delay profile for one channel, and a more accurate measurement Is possible.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a mobile communication system according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a main part of a receiving apparatus of a base station according to the first embodiment of the present invention.
FIG. 3 is a block diagram of a measurement unit according to the first embodiment of the present invention.
FIG. 4 is a block diagram of a divided matched filter unit according to the first embodiment of the present invention.
FIGS. 5A and 5B are diagrams showing examples of connection relationships of selectors according to the first embodiment of the present invention. FIG.
FIG. 6 is a diagram for explaining an averaging process according to the first embodiment of the present invention.
FIG. 7 is a diagram illustrating a format example of received data according to the first embodiment of the present invention.
FIGS. 8A to 8C are diagrams illustrating reception levels in the averaging process according to the first embodiment of the present invention.
FIGS. 9A to 9C are diagrams for explaining path timing according to the first embodiment of the present invention. FIG.
FIG. 10 is a configuration diagram of a matched filter when a new call is generated according to the first embodiment of the present invention.
FIG. 11 is a diagram showing a time width of a delay profile when a new call is generated according to the first embodiment of the present invention.
FIG. 12 is a configuration diagram of a matched filter in stable communication according to the first embodiment of the present invention.
FIG. 13 is a diagram showing a time width of a delay profile during stable communication according to the first embodiment of the present invention.
FIG. 14 is a diagram showing a time width of the delay profile when the correlation value of the delay profile is lowered according to the first embodiment of the present invention.
FIG. 15 is a diagram illustrating a time width of the delay profile when the peak value of the delay profile according to the first embodiment of the present invention falls below a threshold value.
FIG. 16 is a diagram illustrating a time width of the delay profile when the peak value of the delay profile according to the first embodiment of the present invention exceeds a threshold value.
FIGS. 17A and 17B are diagrams for explaining coupling / separation of the matched filter according to the first embodiment of the present invention.
FIG. 18 is a diagram illustrating a main part of a receiving apparatus of a mobile station according to a modification of the first embodiment of the present invention.
FIG. 19 is a diagram illustrating a main part of a CDMA receiver.
20A is a diagram illustrating an example of a delay profile measurement unit, and FIG. 20B is a diagram for describing a delay profile measurement method.
FIGS. 21A to 21C are diagrams for explaining the operation of the delay amount / path detection unit.
22A is a diagram for explaining a despreading process, and FIG. 22B is a diagram showing an example of a time chart showing a despreading operation between a replica code and received data.
FIG. 23 is a diagram illustrating an example of a configuration of a matched filter.
FIG. 24 is a diagram showing a time chart showing the relationship between received data and tap output.
FIG. 25 is a diagram for explaining channel time division;
FIGS. 26A and 26B are diagrams for explaining delay profile measurement periods, respectively. FIGS.
[Explanation of symbols]
1 Delay profile measurement unit
2a ~ 2h Unit matched filter
3a-3h, 9 selector
4 Averaging processing section
4a Power converter
4b Adder
4c dual port memory
5 Pass level judgment part
5a Pass level judgment unit group
6 Path detector
7 Coupling control unit
8,50i Delay / path detector (delay output unit)
11 Average calculator
12 Full adder
13 Divided matched filter
14 slot train
20 Mobile communication system
21 Mobile station
22 Base station
23a building
23b natural products
25,25a CDMA receiver
50a antenna
50b Bandpass filter
50c low noise amplifier
50d frequency converter
50e A / D converter
50-1 to 50-8 RF section
50f Despreading processing unit
50g, 50j replica code generator
52 Control signal output section
60a, 60b shift register
61 cells
62 sectors

Claims (5)

Selecting one of the received data resulting from each of the plurality of code-multiplexed radio frequency signals and the same copy data as one of the plurality of received data, holding and outputting the selected data; and A plurality of unit matched filters that multiply the selected data and the replica code and add and output the multiplication results, and a delay profile measuring unit that outputs the respective reception levels of the radio frequency signals;
Based on the reception level output from the delay profile measuring unit outputs the path timing of the arrival of radio frequency signals, said plurality of units matched filter to control the selection operation in the delay profile measuring unit A CDMA receiver comprising a delay amount output unit for controlling a connection state between the CDMA receivers. The delay amount output unit
A plurality of operation modes of said plurality of units matched filters are defined based on the number of tap stages to be connected, the number of blocks representing the number of blocks a predetermined number of units matched filter from the unit matched filter of the plurality of bound The CDMA receiving apparatus according to claim 1, wherein the switching control is performed in consideration of the switching control. The delay amount output unit
If the new call is generated, if at least one of the case where the correlation level for and the delay profile received state is stable is lowered, based on the number of tap stages of said plurality of units matched filter is connected 2. The CDMA receiving apparatus according to claim 1, wherein the receiving apparatus is configured to switch a plurality of prescribed operation modes. A selector that selects one of the received data resulting from each of the plurality of code-multiplexed radio frequency signals and one of the plurality of received data and the same copy data, and holds and outputs the selected data; A plurality of blocks each including a unit matched filter that multiplies the selection data output from the selector and a replica code, adds the multiplication result, outputs the result, and outputs the selection data after delay; The plurality of blocks are connected in multiple stages so that the selection data delayed in the block is input to the selector in the next block ,
The selector in the plurality of blocks has one of a plurality of received data other than those input to the plurality of blocks up to the preceding stage among the plurality of received data, and the selection data delayed in the preceding block And a delay profile measurement unit configured to output each reception level of the radio frequency signal.
Based on the reception level output from the delay profile measurement unit, and outputs the path timing of the arrival of radio frequency signals, among the plurality of units matched filter controls the selector selecting operation in said plurality of blocks A CDMA system receiver characterized by comprising a delay amount output unit for controlling a connection state . A despreading step of despreading at least one of the plurality of code-multiplexed radio frequency signals and outputting processing data for one specific radio frequency signal of the plurality of radio frequency signals;
A measurement step of measuring a delay profile of the processing data output in the despreading step for a predetermined time;
A reception level output step of outputting a reception level of the specific radio frequency signal based on the delay profile obtained by the measurement;
A CDMA reception method comprising: a switching step of switching a connection state between a plurality of unit matched filters based on the reception level.

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