JPH1174820A - Cdma signal receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely receive a channel with high importance by realizing a small number of correlation devices, code generators, software hand-off, multi-code communication and antenna diversity and sequencing a plurality of CDMA channels with different importance and frequency of occurrence. SOLUTION: The receiver is provided with a plurality of correlation devices 103-1 to 103-4, a plurality of spread code generators 101-1 to 101-4, and a control section 102 and a code assignment table is stored in an internal memory of the control section. The table has a number of each correlation device, a code assigned to each correlation device, timing information of the code, and priority. In the case that a reception signal to be added for software hand-off, multi-code communication, and antenna diversity takes place, the assigned code number and the number of correlation devices are compared and when number of the assigned codes is more than number of correlation devices, the priority in the code assignment table and the priority of the additional reception signal are compared to discriminate whether or not a generated code to the spread code generator is made and the correlation device decides the reception signal subject to inverse spread processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cellular telephone system using a CDMA system, and more particularly to a CDMA signal receiving apparatus such as a mobile station receiver.

[0002]

2. Description of the Related Art Personal communication such as "anytime, anywhere, with anyone, and with any kind of media" is a field that is expected to develop most along with multimedia. Although personal communication is an integrated concept of wired and wireless communication, expectations for wireless communication are particularly high. In wireless communication, portable telephones have been rapidly expanding in recent years, mainly in developed countries, and the conventional analog system is not being able to cover the rapidly increasing demand. For this reason, digital systems that are excellent in subscriber capacity, communication cost, confidentiality, and communication diversity are becoming mainstream.

There are two types of digital systems, TDMA (Time Division Multiple Access) and CDMA (Code Division Multiple Access). The CDMA has been receiving the most attention because it is superior to the TDMA in terms of subscriber capacity. Technology. C
In the DMA system, a spread spectrum technique is used. Spread spectrum is a system in which the occupied frequency bandwidth of a signal is spread over a bandwidth much wider than the occupied frequency bandwidth of information using a code sequence called a spread code and transmitted.

[0004] Spread spectrum techniques include direct spread (D
There are an S) system and a frequency hopping (FH) system, but a direct spreading system is exclusively used in a cellular telephone system. In the CDMA system using DS, on the transmitting side, each mobile station performs spectrum spreading using a different spreading code, and multiplexes a signal of each code channel into the same frequency band and transmits the multiplexed signal. On the other hand, on the receiving side, by performing despreading with the same spreading code as that of the desired receiving channel, only the spectrum of the desired signal is demodulated in a narrow band, and other interference waves become wideband noise.

A CDMA system using such a spread spectrum technique has a large subscriber capacity, allows asynchronous access, is robust against multipath fading by providing a RAKE receiver, and can perform soft handoff.
It has excellent features such as strong resistance to mutual interference with other systems and high confidentiality.

[0006] In the conventional CDMA digital cellular system used in the United States, a signal transmitted on the downlink includes a certain short-period spreading code PN1 and the P-code.
The signal is spread with a signal multiplied by a long-period spreading code PN2 whose chip rate is equal to N1 and whose period is sufficiently longer than PN1. The communication channel of each user can be multiplexed by distinguishing PN1, and PN2 is a code common to each user. Further, the base stations (cells) are distinguished from each other by making the phase of the PN2 different.
As described above, in order to make the phase of the PN2 different among the base stations, each base station has a GPS (Global PoSitioning System).
m) Equipped with a receiver to synchronize between base stations.

FIG. 6 is a block diagram showing a configuration example of a baseband signal processing section in a receiving apparatus for receiving such a CDMA signal. This block includes a signal search unit 601, a control unit 602, despreading units 603-1 to 603-3, a symbol combining unit 604, and a signal processing unit 605. Here, the signal search unit 601 and the despreading units 603-1 to 603-3 are correlators that perform correlation processing with the received signal and despreading. This receiver configuration is described in "Nikkei Electronics" No. 579 (199
April 26, 3). 169-170.

Hereinafter, the operation of the baseband signal processing section will be described. A CDMA baseband signal obtained by frequency-converting a received signal into a baseband is input to the baseband signal processing unit. The baseband signal is a signal spread by the composite signal of the short-period spreading code PN1 and the long-period spreading code PN2 as described above. The signal diffused by the synthesized signal is input to a signal search unit 601 and a direct wave,
The reception timing of each path such as a reflected wave is searched. In this system, a signal (pilot channel) spread only with the PN2 code is transmitted to detect a signal level and a reception timing. Here, the present signal is despread.
Therefore, here, it is necessary to despread the PN2 code, and since the period of the PN2 is very long, a despreading method using a sliding correlation is generally used.

FIG. 7 shows the internal structure of the signal search unit 601. The signal search unit 601 includes a PN2 code generation unit 701,
DLL section (Delay Locked Loop) 702 and the DLL
Amplitude detection section 703 for obtaining correlation amplitude information from the output of section 702
It consists of. The operation of the DLL unit 702 is described in “Spread Spectrum Communication System” (by Mitsuo Yokoyama, Science and Technology Publishing Co., Ltd.), p. 290-pp. As described in detail in 311, it consists of an early phase and a late phase. However, in the description of the present invention, early phase, late
For convenience, the configuration including the punctual phase in addition to the phase
Call.

FIG. 8 shows the internal structure of the PN2 code generator 701. In FIG. 8, squares represent shift registers (delay circuits), which operate with a chip rate clock. Since the type of the PN2 code is common to each cell, only the fixed PN code can be generated. Here, a code generation shift register section 801 and a feedback tap EX-OR are used.
802. However, the control unit 6
When a code generation shift register initialization pulse is input from 02, each code generation shift register unit 801 is initialized to a preset initial value. With such an operation, the PN2 code generation unit 801 can generate PN2 at an arbitrary code phase by the control unit 602. The PN2 code obtained by the PN2 code generation unit 701 is input to the DLL unit 702.

In the DLL section 702, the PN2 code generation section 7
The correlation with the received signal is obtained by using the spreading code obtained from 01 as a reference code. The correlation amplitude is obtained by the amplitude detector 703 using the correlation output. The thus-obtained received signal amplitude information at each path timing is sent to the control section 602, and using the result, the path having the highest received power is selected by the number of despreading sections, and each of the despreading sections 603-603 is selected. The PN code phase information is sent to 1 to 3 so as to synchronize with the PN2 reception timing.

FIG. 9 shows the internal structure of each of the despreading units 603-1 to 603-3. This block differs from the signal search section 601 in that a PN1 code generation section 90 assigned to each user is provided.
2, and an PN2 code generator 901 and an EX-OR unit 903 that performs an exclusive OR operation on the output of the PN2 code generator 902 and the output of the PN1 code generator 902.

FIG. 10 shows the internal structure of the PN1 generator 902. The PN1 code is used for discriminating the user who uses the communication channel in each cell, and the PN1 code may change when the cell where the mobile exists is changed. Therefore, the type of the generated PN1 code needs to be arbitrarily set.

In this example, the PN1 generator 902
Unlike the two-code generation unit 901, the shift register unit 1001 for inputting a feedback tap switching signal for code generation and the shift register unit 10 for latching the feedback tap switching signal for code generation
02, a switch section 1004 for setting the feedback tap is further added. The code generation shift register unit 1
003 and the EX-OR unit 1005 for the feedback tap
Code generating shift register section 80 in N2 generating section 701
1 and a configuration similar to the EX-OR unit 802 for the feedback tap.

The PN1 generating section 902 has a control section 602 in addition to the code generation shift register initialization pulse.
Thus, a feedback tap setting signal for code generation and a feedback tap switching pulse are input.

Hereinafter, a shift register unit 10 for code generation will be described.
The operation of an example in which 03 is composed of seven stages will be described. First, a feedback tap setting signal is input from the control unit 602. In this example, an example is shown in which the feedback tap setting signal is serially input. For example, the rightmost feedback tap (the output of the second code generation shift register from the right).
If you want to use only the input signal "10000"
Input "0", where "1" represents logic "High" and "0" represents "Low".

Similarly, when using the rightmost and fourth feedback taps from the right, "100100" may be input serially. The number of feedback taps that can be set is only six because the output of the rightmost code generation shift register is always fed back. In this way, when the six feedback taps are input, the clock of the feedback tap setting signal input shift register unit 1001 is stopped and the latch state is set.

Next, a feedback tap switching pulse for code generation is input from the control section 602 to a shift register section 1002 for latching a feedback tap switching signal for code generation. When this signal is input, each feedback tap switching information latched in the feedback tap setting signal input shift register unit 1001 is latched in the code generation feedback tap switching signal latch shift register unit 1002.

In this way, the switch unit 1004 is controlled by the latched signal, and the code generation feedback tap is set. Further, an initial value is set in advance in the code generation shift register unit 1003,
Each time a code generation shift register initialization pulse is input, the signal latched in the shift register is initialized to an initial value.

As described above, in the PN1 generating section 902, the desired PN1 code is generated by the control section 602 by inputting the feedback tap setting signal for signal generation and the feedback tap switching pulse, and the shift register for code generation is initialized. By using a pulse, it is possible to output at a desired code phase.

Each of the despreading units 603-1 to 603-3 receives a different code generation shift register initialization pulse and generates a reference code synchronized with the pulse.
Despreading of each path used for AKE reception is realized. DL
Regarding the operation of the L section, DL in the signal search section 601 is described.
Same as L part.

In this way, each of the despreading units 603-1 to 603-1
The despread signal outputs obtained from 3 are input to the symbol combining section 604, and are combined after being subjected to timing adjustment and weighting, thereby achieving ideal path diversity maximum ratio combining.

FIG. 11 shows a rough flow of the receiving section when actually making a telephone call. Generally, when the power of the terminal is turned on (step S1101), first, the system is initialized (step S1102). Thereafter, an initial cell search operation is performed (step S1103). here,
The initial cell search is an operation that first determines which base station to communicate with.

In the present cellular telephone system, as described above, the type of PN2 code used by each base station is common and is distinguished only by the code phase, so that this operation is most performed using one type of PN code. This can be realized only by identifying a reception timing (code phase) having a large correlation amplitude. In this way, after the base station (cell) with which the call is made is determined, RAKE reception of the call channel is performed as described above (step S1104), and the call can be realized.

However, in such a system, since it is necessary to give an accurate offset to the PN2 between the base stations, it is necessary that the base stations be synchronized in time. System) It is necessary to mount a receiver. Therefore, there are problems such as an increase in the size and cost of the base station system and the need for a system for synchronization between base stations, which complicates system expansion such as addition of base stations.

In view of this problem, at present, the P
A CDMA cellular system in which the type of the code of N2 is made different has been studied. Also, in order to enable high-quality mobile communication, the same information is transmitted from two base stations to one terminal, and the terminals perform despreading of different base station signals by despreading units 603-1 and 603-1. In order to realize antenna diversity for despreading signals of different receiving antennas and high-speed mobile communication, a plurality of different short-period spreading codes are assigned to one terminal, and the terminal side simultaneously despreads plural types of short-period spreading codes. Multi-code communication and the like for performing the above are being studied.

[0027]

In such a system, it is necessary to perform individual despreading for different spreading codes and code timings using a plurality of correlators. Requires an extremely large number of correlators and code generators. Also, the common broadcast information transmitted from the base station may be transmitted on another code channel, for example, a signal search channel. In this case, a correlator, a code generator, and a demodulator that periodically receive the common broadcast information Is needed. However, soft handoff, antenna diversity, and multicode communication are not always performed, and dynamic operation is performed as needed.

The present invention has been made in view of the above problems, and realizes soft handoff, multicode communication, and antenna diversity by effectively using a small number of correlators and code generators. It is another object of the present invention to provide a CDMA signal receiving apparatus which ranks a plurality of CDMA channels having different degrees of importance and occurrence frequency and reliably receives a channel having a high degree of importance.

[0029]

The invention according to claim 1 is
CDM multiplexed by distinguishing types of spreading codes
This is a cellular telephone system that receives an A signal, has a plurality of correlators, a plurality of spreading code generators, and a reception control unit, and stores a code assignment table in a memory inside the reception control unit. A DLL (sliding correlation) and a matched filter (MF) are considered as correlators.
As the spreading code generator, a combination of a short cycle sequence generator and a long cycle sequence code generator can be considered. Further, the table holds the number of each correlator, the code assigned to each correlator, the timing information of the code, and the priority. Soft handoff, multi-code communication, when a received signal to be added for antenna diversity occurs, compare the number of allocated codes and the number of correlators, and if the number of allocated codes is larger than the number of correlators, the code allocation table By comparing the priorities of the correlators with the priorities of the additional received signals, it is possible to perform signal switching by switches of all or some of the correlators and switching of generated codes to the spreading code generator. Then, the received signal to be despread by the correlator is determined.

According to the second aspect of the present invention, priorities are assigned in order of channels having higher importance, and the code assigned to the communication channel having the highest reception level is stored in the code assignment table having the highest priority. Assigning a timing, assigning a code and a timing assigned to a common broadcast channel and a multi-code channel having the same timing as the speech channel to a code assignment table having a second priority, and a code assignment table having a third priority. , A code and a timing of a communication channel of a soft handoff destination are allocated, and a timing of an antenna diversity reception channel and a multipath reception channel are allocated to a code allocation table having the lowest priority.

[0031] The invention according to claim 3 is characterized in that the contents of the code assignment table are rewritten according to a change in the reception level due to fading.

In the CDMA signal receiving apparatus according to the present invention, the multiplexed C
A CDMA baseband signal, which receives a DMA signal and is obtained by frequency-converting the signal into a baseband, is input to a plurality of correlators numbered in advance. When the correlator is a matched filter, there is an advantage that the synchronization circuit is simplified and that a plurality of multipath signals received by the same antenna can be demodulated by one correlator.

There are a digital MF and an analog MF as a method of realizing the MF. In particular, when a matched filter is formed by analog technology, the required operating clock frequency can be suppressed, and low power consumption can be expected.

The reception control unit holds a code assignment table in an internal memory. Further, the reception control unit sets spreading codes having different types or timings as reference codes to the plurality of spreading code generators. In each of the plurality of correlators, the correlation between the input signal and the obtained reference code is obtained. When a received signal to be added for soft handoff, multicode communication, antenna diversity, RAKE reception, etc. is generated and codes are allocated to the spread code generator, the number of allocated codes is compared with the number of correlators, and the number of allocated codes is determined. If more than the number of correlators, determine the priority of the additional received signal, by comparing the priority of the code allocation table and the priority of the additional received signal, if the priority of the additional received signal is high Performs switching of the generated code to the signal changeover switches of all or some of the correlators and the spreading code generator, and does not perform the switching otherwise.
Thereby, a signal with a high priority can be effectively received. If the number of assigned codes is smaller than the number of correlators, set the codes to the spread code generator as they are and store the codes themselves or the type and code timing of the codes and the number of the set correlators in the memory in the corresponding code allocation table. Hold. As a method of comparing the number of assigned codes, it is conceivable to count the set total number of correlators and hold it at another position in the memory, and a flag is obtained by comparing this value with a predetermined total number of correlators. Thus, a method of determining whether or not the generated code needs to be replaced by a flag may be considered.

As a method of setting the priority of the reception control unit, a method of prioritizing the channels in the order of higher importance can be considered. For example, the code and the timing assigned to the speech channel with the highest reception level are held in the code assignment table having the highest priority,
The code allocation table having the second priority stores the code and timing allocated to the common broadcast channel and the multi-code channel having the same timing as the speech channel, and the soft handoff is performed to the code allocation table having the third priority. The code and the timing of the previous communication channel are held, and the code allocation table having the lowest priority has an antenna diversity reception channel,
And maintaining the timing of the multipath reception channel.

A speech channel with a high reception level is most important for stable speech channel reception. Also, the common broadcast channel and multi-code reception are not always required, but must be received whenever necessary. Also, the reception of the call channel of the soft handoff destination is more important than other multipath channels and antenna diversity for handoff without interruption,
The multipath channel and the antenna diversity reception channel have relatively low importance, but need to be received when the above-mentioned various channels are not received because they are indispensable for stable and high-quality signal reception. When the signal level of the channel currently being received with the highest priority changes due to fading and the signal with the highest reception level changes to another channel in the table, only the table is rewritten.

[0037]

FIG. 1 is a block diagram of a configuration example of a baseband signal processing unit according to a first embodiment of the present invention. This block includes spreading code generators 101-1 to 101-4, control unit 102, correlators 103-1 to 103-4, selector unit
4. Broadcast channel demodulation units 105-1 and 105-2, demodulation unit 106
-1 to 3, a symbol combining unit 107, and a signal processing unit 108.

An input signal in this block diagram is a CDM obtained by frequency-converting a received signal into a baseband.
A baseband signal. The baseband signal is spread by a spread signal obtained by multiplying a short-period spreading code PN1 and a long-period spreading code PN2 whose period is sufficiently longer than PN1 as in the conventional example. However, the PN2 code is a different type of code depending on the base station. In addition, as the baseband signal, received signals from two antennas are output in two systems, thereby enabling antenna diversity.

FIG. 2 shows the internal structure of the spreading code generator 101. This block includes a PN2 code generator 201, PN1
Code generator 202, PN2 code generator 201 output and PN
EX-O which takes the exclusive OR of the output of one code generation unit 202
An R unit 203 is provided.

The PN1 code generation section 202 has the same configuration and performs the same operation as the PN1 code generation section 902 described in the conventional example. However, as described in the conventional example, when a signal (pilot channel) spread only with the PN2 code is transmitted for signal level and reception timing detection, the PN1 code generation unit 202 is unnecessary. It is. Note that, in FIG. 2, a DLL unit 204 and an amplitude detection unit 205 show constituent elements of the correlator 103.

FIG. 3 shows the internal structure of the PN2 code generator 201. The PN2 code distinguishes base stations by different types of codes, and it is necessary that the type of PN2 code generated can be set arbitrarily. Accordingly, in this example, the shift register section 301 for inputting the feedback tap switching signal for code generation, the shift register section 302 for latching the feedback tap switching signal for code generation, the shift register section 303 for code generation, and the switch for setting the feedback tap are provided. And an EX-OR unit 305 for feedback tap.

When a code generation shift register initialization pulse is input from the control unit 102, each code generation shift register is initialized to a preset initial value.
Further, a feedback tap setting signal for code generation and a feedback tap switching pulse are input from the control unit 102. The operation is the same as that of the conventional PN1 code generator 902. As described above, the spread code generator 101 can switch the type of the PN2 code according to the control signal from the control unit 102. The spreading code generated by the spreading code generator 101 is input to the correlator 103.

The correlator 103 comprises a DLL or a matched filter, selects one of the two received signals,
It outputs a correlation output signal between the signal generated by the spread code generator 101 and the received signal. When the correlator 103 is a matched filter, there is an advantage that the synchronization circuit is simplified and that a plurality of multipath signals received by the same antenna can be demodulated by one correlator. Further, when a matched filter is formed by analog technology, the required operating clock frequency can be suppressed, and low power consumption can be expected.

In a cellular telephone system using the CDMA system, a broadcast channel signal for transmitting a control signal common to all mobile stations and a communication channel for each user may be simultaneously multiplexed using different PN1 codes and transmitted. The output of the correlator 103 is selected by the selector unit 104.

The signal correlated with the spread code of the broadcast channel by the correlator 103 is guided to the broadcast channel demodulation unit 105 by the selector unit 104, the digital signal of the broadcast channel is demodulated, and the information of the broadcast channel demodulation unit 105 is controlled. Part 10
2 is input. The broadcast channel demodulation unit may be one or plural. A signal obtained by correlating the spread code of the traffic channel with the correlator 103 is output from the selector 104.
And guided to one of the plurality of demodulation units 106,
The demodulation section 106 demodulates the digital signal of the communication channel.

The output signal of the demodulation unit 106 is RAKE-combined by the symbol combination unit 107, and the signal processing unit 108 performs signal processing in accordance with information content, for example, voice, image, data, and the like. Broadcast channel demodulators 105 are prepared as many as the number of correlators 103. For example, at the time of initial cell search, PN2 codes corresponding to base stations different from the PN1 code of the broadcast channel are assigned to all code generators 101 to generate spread codes. Then, it is conceivable that the correlator 103 correlates the broadcast channel signals of a plurality of base stations, and the demodulator 106 simultaneously demodulates the plurality of broadcast channels at high speed.

When the initial cell search operation is completed, the PN1 code and the PN2 code generated by the spreading code generator are switched, and the apparatus enters the RAKE reception of the communication channel of the specific base station. The broadcast channel does not need to be constantly demodulated, and it is often sufficient to intermittently receive information.

The codes set in the respective spread code generators 101 are all the same when the signal of a specific base station is strong.
A multipath signal of a code and an antenna diversity signal are used. If the signals from two base stations are equally strong, a different PN2 code is generated as a spread code to receive signals from two different base stations. There is a case where the signal is set and received in the device 101, so-called soft handoff can be realized.

When a certain mobile station moves from a cell of one base station to a cell of another base station, there is an advantage that if soft handoff is performed, there is no signal interruption due to switching of base stations. The configuration of the selector unit 104 may be such that the outputs of some of the correlators 103 are fixedly guided to the broadcast channel demodulation unit 105 or the demodulation unit 106.

FIG. 4 is a diagram showing another embodiment, and shows a configuration of a baseband signal processing section in a case where multicode communication is realized. In FIG. 4, one of the correlators 103 uses a second PN1 code assigned to the user to communicate more information, and uses a second PN1 code to transmit a CD on a multi-code channel.
MA multiplexed and transmitted and the corresponding second PN1
A spreading code using the code is generated from the spreading code generator 101, and the correlation is obtained by the correlator 103. The output is guided to the demodulation unit 106-3 through the selector unit 104. Since the output of the demodulation section 106-3 is different from the output of the other demodulation sections 106, it is input to the signal processing section 108 without passing through the symbol synthesis section 107, and the signal processing section 108 performs processing in accordance with the information content. Done. Operations other than the multi-code communication are the same as in the first embodiment.

As described above, the spreading code generator 101
Various codes are set for the PN1 code and the PN2 code set in the above. Various reception channels are correlated and demodulated. However, since the mobile station is required to be small, the numbers of the spreading code generators 101 and the correlators 103 cannot be so large.

On the other hand, the importance and reception frequency of the reception channel differ depending on the necessity. For example, a receiving channel during a call has the highest importance in order not to interrupt communication, and it is necessary to always receive a signal having the highest reception level during a call. Further, the multi-code channel needs to be always received during communication in order to prevent interruption of communication during multi-code reception, though the frequency of occurrence during communication is low.

The reception of the communication channel of the soft handoff destination is more important than other multipath channels and antenna diversity for a handoff without an instantaneous interruption.
The multipath channel and the antenna diversity reception channel have relatively low importance, but need to be received when the above-mentioned various channels are not received for stable and high-quality signal reception. For this reason, when a communication channel to be newly received comes out, or when performing path switching by multipath, a priority is set according to the reception channel, and it is determined whether or not to set a code in the spreading code generator 101 according to the priority. By making the determination, a channel with a higher priority can be reliably demodulated.

As for the priority, the received signal of the speech channel having the highest signal level is assigned to the highest priority, and the second priority is assigned to the common broadcast channel and the code assigned to the multi-code channel at the same timing as the speech channel. Preferably, the code and timing of the communication channel of the soft handoff destination are assigned to the third priority, and the timing of the antenna diversity reception channel and the multipath reception channel are assigned to the lowest priority. Which priority code is set to which code generator 101 is managed by a code assignment table provided in a memory (not shown) in the control unit 102.

FIG. 5 is a diagram showing an operation flow in the control unit 102 when codes are set in the spread code generator 101 in the above two embodiments. Hereinafter, the method of code setting will be described with reference to FIG.

The control unit 102 determines the priority when a code to be set occurs (S502). The number of code generators 101 is compared with the number of codes to be set (S503).
When the number of the code generators 101 is large, the setting information for the code generators such as the spreading code and the timing is stored in a code allocation table together with the priority and the code and the timing are stored in one of the code generators 101 (S504). Is set (S5
05).

If the number of codes to be set is larger than the number of code generators 101, the contents of the code allocation table are searched (S507), and if there is a spreading code generator 101 to which a code with a lower priority is set. (S50)
8) If set, the contents of the code assignment table are rewritten (S510), and the code and timing generated by the corresponding spread code generator are changed (S511).

If there is no code having a low priority in the code assignment table, the process is terminated without setting the code (S50).
9). As a result, demodulation can be reliably performed on a channel with a high priority. The reception level fluctuates while receiving the call channel, the reception channel of the maximum signal level changes,
When the channel with the highest signal level is in the code assignment table, the code assignment table is updated to the latest state by rewriting the priority of the code assignment table.

[0059]

According to the present invention, a CD for receiving a multiplexed CDMA signal by discriminating the type of spreading code.
In the MA signal receiving apparatus, soft handoff, multi-code communication, and the like can be effectively performed with a small number of correlators, and a highly important channel can be reliably demodulated.

[Brief description of the drawings]

FIG. 1 is a block diagram of a configuration example of a baseband signal processing unit according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a code generator in the baseband signal processing unit according to the first embodiment of the present invention.

FIG. 3 is a block diagram of a PN2 code generation unit in the signal search unit according to the first embodiment of the present invention.

FIG. 4 is a block diagram of a configuration example of a baseband signal processing unit according to a second embodiment of the present invention.

FIG. 5 is a flowchart for code assignment according to the first and second embodiments of the present invention.

FIG. 6 is a block diagram of a configuration example of a conventional baseband signal processing unit.

FIG. 7 is a block diagram of a signal search unit in a conventional baseband signal processing unit.

FIG. 8 is a block diagram of a PN2 code generation unit in a conventional signal search unit.

FIG. 9 is a block diagram of a despreading unit in a conventional baseband signal processing unit.

FIG. 10 is a block diagram of a PN2 code generator in a conventional despreading unit.

FIG. 11 is a flowchart of a receiving unit when making a call.

[Explanation of symbols]

101-1 to 104-4 Spreading code generator 102 Control unit 103-1 to 4 Correlator 104 Selector unit 105-1 to 2 Broadcast channel demodulation unit 106-1 to 3 Demodulation unit 107 Symbol combining unit 108 Signal processing unit 202, 701 901 PN1 generating section 201, 902 PN2 generating section 204, 702, 904 DLL section 205, 703 Amplitude detecting section 203, 903 EX-OR section 301 in PN1 code output and PN2 code output 301, 1001 For input of feedback tap switching signal for code generation Shift register section 302, 1002 Code generation feedback tap switching signal latch shift register section 303, 801, 1003 Code generation shift register section 304, 1004 Feedback tap setting switch section 305, 802, 1005 Feedback tap EX-OR section 601 Signal search unit 602 control Part 603-1～3 despreading unit 604 symbol combining unit 605 signal processing unit

Claims (3)

[Claims] 1. A CDMA signal receiving apparatus, such as a cellular telephone system, for receiving a multiplexed CDMA signal by distinguishing types of spreading codes, comprising: a plurality of correlators; a plurality of spreading code generators; In the reception control unit, a priority is given to a code and a timing to be assigned to the spreading code generator, and when code assignment equal to or more than the number of correlators occurs, a determination of code replacement is made based on the priority. CD characterized by performing
MA signal receiving device. 2. A code having the highest priority and a timing and a code assigned to a communication channel having the highest reception level are assigned as a timing, a code and a timing having a second priority are assigned as a common broadcast channel, and The code and timing assigned to the multi-code channel having the same timing as the speech channel are assigned. The code and timing of the speech channel of the soft handoff destination are assigned as the third priority, and the code and timing having the lowest priority are assigned as 2. The CDMA signal receiving apparatus according to claim 1, wherein codes and timings of an antenna diversity reception channel and a multipath reception channel are assigned. 3. The CDMA signal receiving apparatus according to claim 1, wherein the priority of code allocation is changed according to a change in the reception level.