JPH11145933A - System and equipment for spread spectrum communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the privacy of communication while maintaining high speed in synchronism capture. SOLUTION: When exchanging the main body of a transmission between first and second spread spectrum communication equipment while spreading it by using a spread code, during the period of that communication, the kind of a spread code sequence to be applied is cyclically or irregularly changed. After synchronism is once established, the kind of the spread code sequence is changed at suitable time intervals so that the privacy of communication can be improved. Further, the number of bits in a frame header is almost equal and high-speed pull-in setting ability is not lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication system and apparatus, and is suitably applied to, for example, a CDMA (code division multiple access) mobile communication system.

[0002]

2. Description of the Related Art In a CDMA mobile communication system, a multiple spreading method has been proposed in which a part of a once-spread code sequence is spread again in order to reduce the synchronization detection time of a long-period code sequence. For example, a method has been proposed in which a header (a pattern for synchronization acquisition) is added to data and only the header part is spread twice.

[0003]

The feature that the synchronization is easily acquired by the multiple spreading method is, conversely, that the synchronization is easily acquired by others. for that reason,
In terms of communication confidentiality (security), this was an element that could be a weak point. In particular, the smaller the number of bits in the header portion, the easier it is to acquire synchronization.

In order to make it difficult for others to acquire the synchronization, the number of bits in the header part is increased. In such a case, even the original receiving side requires a long time to acquire the synchronization. It will cost.

[0005] Therefore, there is a need for a spread-spectrum communication system and apparatus that further enhances confidentiality of communication while maintaining high-speed synchronization acquisition.

[0006]

According to a first aspect of the present invention, a transmission signal body is spread and transmitted between a first and a second spread spectrum communication apparatus using a spreading code. In the spread spectrum communication method, the type of spread code sequence to be applied is changed during communication between the first and second spread spectrum communication apparatuses.

According to a second aspect of the present invention, there is provided a spread-spectrum communication having spread code generating means for generating a spread code, and spread modulation means for spreading a transmission signal body using the spread code from the spread code generating means. In the device, based on the agreement with the opposed spread spectrum communication device, the type of the spread code sequence generated from the spread code generating means, the spread code sequence type change control means for changing during the transmission period of the transmission signal body, It is characterized by having.

Further, a third invention provides a spread code estimating means for estimating a spread code phase in a received signal to generate a spread code, and despreading the received signal using a spread code from the spread code estimating means. In a spread spectrum communication apparatus having a despreading means, a type of a spread code sequence generated from the spread code estimating means is changed during a reception period of the reception signal based on an agreement with an opposite spread spectrum communication apparatus. The present invention is characterized in that it has a spreading code sequence type change control means for causing it to change.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following embodiments of the present invention, once synchronization has been achieved, the type of spreading code sequence is changed at appropriate time intervals to maintain high-speed synchronization pull-in capability. It is intended to enhance security. That is, a new technical idea that is more appropriate to be called code hopping than frequency hopping is introduced for the first time.

(A) First Embodiment Hereinafter, a first embodiment in which a spread spectrum communication system and apparatus according to the present invention are applied to a mobile communication system of a multiplex spread CDMA system will be described in detail with reference to the drawings. .

FIG. 1 is a functional block diagram showing a main part of a transmission configuration of, for example, a traffic channel of a base station or a mobile station. FIG. 2 is a block diagram of a mobile station or a base station corresponding to the transmission configuration. FIG. 2 is a functional block diagram showing a main part of the configuration.

In FIG. 1, the transmission components of the traffic channel include a framing unit 11, an error correction encoding unit 1
2. information modulator 13, spreading modulator 14, spreading code generator 15, header adding unit 16, header spreading code generator 1
7, a frequency converter 18, a main controller 19, and a code controller 20.

The framing unit 11 is provided with user information destined for the opposite mobile station or base station output by a user information buffer unit (not shown). Framing unit 11
Is for converting the user information into a frame and providing the frame to the error correction encoding unit 12. The error correction coding unit 12 performs error correction coding on the frame of the input user information and supplies the frame to the information modulation unit 13. As the error correction coding method here, for example, a convolution coding method is applied. The information modulation unit 13 performs information modulation (for example, BPS) on an input signal regardless of the type of information.
K, QPSK, etc.) to be provided to the spread modulator 14.

The spread modulator 14 spreads and modulates the information-modulated signal using a spread code (for example, a PN code) provided from a spread code generator 15, and a header adder 16.
To give. Here, the spreading code generation unit 15
Under the control of the code control unit 20, as described later, a different spreading code sequence is set for each multiple of a frame integer (the integer does not have to be a fixed value; in the first embodiment, a fixed value). It is generated and given to the spread modulator 14.

The header adding section 16 spreads the pattern of the frame header (mainly for synchronization acquisition) with the spreading code for the header given from the spreading code generating section 17 for the signal, and outputs the signal from the spreading modulation section 14. To the frequency conversion unit 18. Here, the header spreading code generator 17 also controls the frame integer (the integer does not have to be a fixed value, as described later) under the control of the code controller 20; in the case of the first embodiment, A different spreading code sequence is generated for each (fixed value) times and given to the header adding unit 16.

The frequency conversion unit 18 up-converts the frequency of the output signal from the header addition unit 16 to a radio frequency band (RF band). The RF signal obtained in this manner is power-amplified by a power amplifier (not shown), and is then given to a shared antenna via a shared antenna (not shown) and radiated to space.

The main controller 19 basically controls the entire base station or mobile station and executes call processing. In the first embodiment, the main control unit 19
In the case of negotiation for allocating a traffic channel or the like between the mobile station or the main control unit of the base station and the like, the spreading code and the header output from the spreading code generator 15 and the header spreading code generator 17 are used. The type change pattern information of the code sequence of the spreading code is exchanged with the main control unit of the opposing mobile station or base station and shared. The main control unit 19 provides the code control unit 20 with information necessary for changing the type of the spreading code, such as the type change pattern information and timing information for changing the type of the generated spreading code sequence.

In the case of negotiation between the base station and the main control unit of the mobile station for sharing the type change pattern information, the main control unit on the side of the base station takes the initiative and sets the plurality of mobile stations. The type change pattern information is determined so that the spread codes of the two do not become the same at the same time.

The code control unit 20 is based on the information from the main control unit 19, and the code sequence of the spread code output from the spread code generation unit 15 and the header spread code generation unit 17 and the code sequence of the header spread code ) Is changed as appropriate.

Next, the operation of the traffic channel transmission configuration shown in FIG. 1 will be briefly described.

In the frame switching section 11, the user information is divided into frames of a predetermined length, then subjected to error correction coding in an error correction coding section 12, and further subjected to information modulation in an information modulation section 13. It is provided to the spread modulator 14.

A spreading code sequence of a type determined at that time under the control of the main control unit 19 and the code control unit 20 is supplied from the spreading code generation unit 15 to the spreading modulation unit 14. Spread modulation is performed using a spreading code. The main control unit 19 also controls the header adding unit 16.
And a header spreading code sequence of a type determined at that time under the control of the code control unit 20.
In the header adding unit 16, the pattern of the frame header is spread using the header spreading code from the header spreading code generation unit 17, added to the signal from the spread modulation unit 14, and added to the frequency conversion unit 18. Given to.

The signal output from the header adding unit 16 is
As in the conventional case, after the frequency conversion, transmission power control (power amplification), and other processing are performed, the light is radiated into space.

Next, a configuration for receiving a traffic channel will be described with reference to FIG.

In FIG. 2, the receiving components of the traffic channel include a frequency converter 30, a despreader 31, a spreading code estimator 32, a switch 33, a header despreader 34,
It has a spreading code estimating unit for header 35, an information demodulating unit 36, an error correction decoding unit 37, a frame decomposing unit 38, a main control unit 39, and a code control unit 40.

The frequency converter 30 down-converts an RF band received signal, which is captured by a transmitting / receiving antenna (not shown) and input to a receiving configuration via an antenna transmitting / receiving duplexer (not shown), and converts the signal into a baseband frequency band. This is given to the despreading unit 31.

The despreading unit 31 uses the spreading code given from the spreading code estimating unit 32 for the baseband signal from the frequency conversion unit 30 and performs a reverse process of the process performed by the spreading modulation unit 14. It is to spread. Here, the spreading code estimating unit 32 incorporates a matched filter or a sliding correlator, etc., and estimates (synchronizes with) a spreading code phase for a control channel in a baseband signal to generate a spreading code. . Also, the spreading code estimation unit 32
Generates the type itself of the spreading code sequence instructed by the code control unit 40.

The switch section 33 passes only the signal from the despreading section 31 arriving during the period designated by the header despreading section 34 and supplies it to the information demodulation section 36. The header despreading unit 34 uses the header spreading code from the header spreading code estimating unit 35 to recognize the frame header portion in the signal from the despreading unit 31 and performs control to instruct passage only during the frame information period. A signal is given to the switch unit 33. The header spread code estimating unit 35 also incorporates a matched filter or a sliding correlator, etc., and estimates the phase of the header spread code in the output signal from the despreading unit 31 to generate a header spread code.
Further, the header spreading code estimating unit 35 generates the type of the header spreading code sequence specified by the code control unit 40.

The information demodulation unit 36 operates when the output signal of the switch unit 33 is given. The information demodulation unit 36 performs information demodulation, which is the reverse process of the process performed by the information modulation unit 13, on the output signal. And gives it to the error correction decoding unit 37. The error correction decoding unit 37 includes the error correction encoding unit 12
And performs error correction decoding, which is the reverse process of the process described above, and gives the result to the frame decomposition unit 38. Frame disassembly unit 38
Is to decompose the signal of the frame unit given from the error correction decoding unit 37, and assemble and output the user information that the opposing base station or mobile station tried to transmit.

The main control section 39 basically controls the entire base station or mobile station and executes call processing. As described above, in the first embodiment,
The main control unit 39 is configured to perform a spread code estimating unit 32 in a negotiation or the like for allocating a traffic channel with the main control unit 19 of the opposing base station or mobile station.
And the change pattern information of the code sequence of the spreading code and the spreading code for the header output from the spreading code estimating unit 35 for the header is exchanged with the main control unit 19 of the opposing base station or mobile station and shared. The main control unit 39 provides the code control unit 40 with information necessary for changing the type of the spread code sequence, such as the change pattern information and timing information for changing the type of the generated spread code sequence.

The code control unit 40, based on the information from the main control unit 39, outputs the code sequence of the spread code and the header spread code output from the spread code estimating unit 32 and the header spread code estimating unit 35. ) Is changed as appropriate.

The change pattern transmitted and received by the main control unit 19 of the transmission configuration and the main control unit 39 of the reception configuration may be determined by the base station alone, but also has a relationship with peripheral base stations. A base station control device or a radio system control station which is a higher-level device than a base station and a mobile station may be determined from the control aspect of the entire system.

Next, the operation of the traffic channel receiving configuration shown in FIG. 2 will be briefly described.

A reception signal in the RF band, which is captured by a transmission / reception shared antenna (not shown) and input to the reception configuration via the antenna transmission / reception duplexer, is down-converted in the frequency converter 30 and converted into a baseband frequency band. It is provided to the despreading unit 31.

The despreading unit 31 is supplied with a kind of spreading code sequence determined at that time under the control of the main control unit 39 and the code control unit 40 from the spreading code estimating unit 32. The baseband signal from the conversion unit 30 is subjected to despreading, which is the reverse process of the process performed by the spreading modulation unit 14, using the spreading code given from the spreading code estimation unit 32.

The header despreading unit 34 is supplied with a header spreading code sequence of a type determined at that time under the control of the main control unit 39 and the code control unit 40 from the header spreading code estimating unit 35, The despreading unit 34 recognizes the frame header portion of the signal from the despreading unit 31 using the header spreading code from the header spreading code estimating unit 35, and outputs the frame information of the signal from the despreading unit 31. Only passes through the switch unit 33.

In the information demodulation unit 36, the switch unit 3
3 is demodulated, the error correction decoding section 37 performs error correction decoding, the frame decomposing section 38 decomposes the signal in units of frames, and the opposite base station or mobile station transmits the signal. The attempted user information is assembled.

FIG. 3 is a functional block diagram showing a detailed configuration of the spreading code generator 15 in the first embodiment.

In FIG. 3, the spreading code generator 15 includes a plurality (N) of original spreading code generators 50-1 to 50-N;
It has a selection switch 51, a code conversion unit 52, and a frame timing generation unit 53.

Each of the original spreading code generators 50-1,..., 50-
N each generate a different type of spreading code sequence, and perform an output operation in a frame period in which only one of the original spreading code generation units 50-n specified by the code control unit 20 exists. Each original spreading code generator 50
-1,..., 50-N are for generating different types of spreading code sequences due to different generator polynomials in the case of a PN code, for example. Also, for example, in one PN code generator that generates a PN code sequence having a very long cycle according to the same generator polynomial, by providing output taps at positions where the phases are sufficiently different, functionally different types are provided. A plurality of original spreading code generators 50 for generating a spreading code sequence of
,..., 50-N may be realized.

Under the control of the code control unit 20, the selection switch 51 selects a spread code from the original spread code generation unit 50-n which is performing an effective output operation during the frame period, and sends the selected spread code to the code conversion unit 52. Is to give.

The code conversion section 52 forms a spread code for one frame from the spread code given from the selection switch 51 and gives it to the spread modulation section 14 (see FIG. 1). For example, assuming that X-times spreading is performed and the period of the spreading code sequence of the original spreading code generating unit 50-n is Y bits,
If Y is greater than or equal to X, X bits are cut out of the Y bits to form a spreading code in the current frame. Conversely, if Y is less than X, Y bits are repeated to form X bits (Y Is not necessarily an integer), thereby forming a spread code in the current frame.

When X bits are cut out of Y bits, the cutout range may be determined by the base station and the mobile station. Further, when forming an X-bit spreading code by repeating Y bits, the Y bits need not be the period of the spreading code sequence of the original spreading code generation unit 50-n.

The frame timing generator 53 outputs the code control unit 20 every predetermined number of frames (for example, one frame).
For switching the type of spreading code sequence.

The general function of the code control unit 20 has been described above. In the case of the first embodiment, the code control unit 20
Specifically, it functions as follows. That is, although not shown (see FIG. 1), the code control unit 20 is given a selection pattern of the original spread code generation units 50-1 to 50-N for outputting a spread code from the main control unit 19. The code control unit 20 includes the frame timing generation unit 5
3 instructs to switch the type of spreading code sequence, the original spreading code generation unit 50 that has been selected on the selection pattern until now.
The original spreading code generator 50-m and the selection switch 51 are controlled so as to select the spreading code from the original spreading code generator 50-m next to -n.

With the above detailed configuration, the spreading code generator 15 can generate a spreading code of a different type of spreading code sequence for each predetermined number of frames (for example, one frame).

The detailed configuration of the header spreading code generator 17 is the same as the detailed configuration of the spreading code generator 15 shown in FIG.
2 and a detailed configuration for generating a spread code and a header spread code other than the synchronization acquisition configuration of the header spread code estimator 35 are the same as the detailed configuration of the spread code generator 15 shown in FIG. The detailed description of the operation is omitted. Of course, the circuit of FIG. 3 can be shared by the transmitting side and the receiving side.

As described above, according to the first embodiment, the types of the spreading code sequence and the header spreading code sequence are changed every predetermined number of frames.
The confidentiality of the communication can be increased as compared with the related art. In this case, the number of bits of the frame header is almost the same as that of the conventional art, so that the high-speed synchronization pull-in capability is not reduced.

In a service capable of retransmission control such as packet communication, the same content may be transmitted and received a plurality of times, and the confidentiality can be reduced by that amount. The form is valid.

Even if a plurality of types of spreading code sequences are combined under the condition that they do not overlap in the same period, the number of combinations is large, and there are many mobile stations simultaneously communicating with one base station or its neighboring base stations. However, a spreading code can be assigned so as to avoid collision. Conversely, it is expected that the base station can accommodate more mobile stations than before.

(B) Second Embodiment Next, a first embodiment in which a spread spectrum communication system and apparatus according to the present invention are applied to a mobile communication system of a multiplex spread CDMA system will be described in detail with reference to the drawings. I do.

Also in the second embodiment, the schematic configuration of the transmission configuration and the reception configuration of the traffic channel can be shown in FIGS. 1 and 2 according to the above-described first embodiment. Therefore, description of the schematic configuration and operation of the transmission configuration and the reception configuration of the traffic channel is omitted. 1 and 2 are also used in the following description.

The second embodiment is different from the first embodiment mainly in the configuration for changing the code sequence of the spreading code and the spreading code for the header.

FIG. 4 is a functional block diagram showing the detailed configuration of the spreading code generator 15 in the second embodiment. The same and corresponding parts as those in FIG. 3 according to the first embodiment are shown in FIG. The same reference numerals are given.

In FIG. 4, the spreading code generator 15 of the second embodiment is such that the frame timing generator 53 of the first embodiment is omitted, and the main controller 19 also instructs the switching timing of the type of spreading code. The other components are the same as those of the first embodiment.

In the second embodiment, the main control unit 19 transmits information specifying the switching timing of the type of the spread code sequence to the main control unit 39 (see FIG. 2) in the opposed reception configuration. , And instructs the code control unit 20 to switch the type of the spread code sequence at a timing according to the information.

Here, the exchange of information defining the switching timing between the two main control units 19 and 39 may be performed together with the type change pattern at the time of the initial negotiation for the call connection.

At the time of the initial negotiation for the call connection, only the type of the first spreading code sequence is determined, and then, for example, from the main control unit of the base station to the other main control unit. Alternatively, the switching may be instructed by transmitting the type of the spread code sequence after switching through an associated control channel associated with the traffic channel or a common control channel common to a plurality of traffic channels.
In this case, the main control unit of the base station (1) does not execute the switching of the type of the spread code sequence when the number of traffic channels provided for communication is small, and instructs the switching when the number increases. (2) Switching may be instructed by the passage of time irrespective of regular or irregular, and (3) Switching may be performed based on the state of propagation path characteristics (bit error rate etc.). It may be instructed.

In any case, in the second embodiment, when the main control unit 19 instructs the switching of the type of the spread code sequence, the code control unit 20 transmits a new code indicated by the main control unit 19. The original spreading code generator 50-m and the selection switch 51 are controlled so as to select the spreading code from the original spreading code generator 50-m.

In the second embodiment, the detailed configuration of the header spreading code generator 17 is the same as the detailed configuration of the spreading code generator 15 shown in FIG. The detailed configuration for generating the spread code and the header spread code excluding the synchronization acquisition configuration of the code estimator 32 and the header spread code estimator 35 is the same as the detailed configuration of the spread code generator 15 shown in FIG. Therefore, illustration and detailed description of the operation are omitted.

According to the second embodiment, as in the first embodiment, confidentiality can be improved without delaying synchronization pull-in.

Further, according to the second embodiment, the switching timing of the type of the spreading code sequence and the type of the spreading code sequence for the header is also controlled by the main control unit. Can be further enhanced. In addition, there is an effect that the types of the spread code sequence and the header spread code sequence after the switching can be arbitrarily changed after the start of communication.

(C) Third Embodiment Next, a third embodiment in which a spread spectrum communication system and apparatus according to the present invention are applied to a mobile communication system of a multiplex spread CDMA system will be described in detail with reference to the drawings. I do.

Also in the third embodiment, if a schematic configuration of a transmission configuration and a reception configuration of a traffic channel is illustrated, it can be represented in FIGS. 1 and 2 according to the first embodiment. Therefore, description of the schematic configuration and operation of the transmission configuration and the reception configuration of the traffic channel is omitted. 1 and 2 are also used in the following description.

The third embodiment is different from the first embodiment mainly in a component for changing a code sequence of a spreading code and a header spreading code.

FIG. 5 is a functional block diagram showing the detailed configuration of the spreading code generator 15 in the third embodiment. The same and corresponding parts as those in FIG. 3 according to the first embodiment are described. The same reference numerals are given. FIG. 6 is a block diagram showing a detailed configuration example of the original spreading code generator 50 in FIG.

In FIG. 5, the spread code generator 15 of the third embodiment is different from the spread code generators 50-1 to 50-N and the selection switch 51 of the first embodiment in FIG. Is provided with one original spreading code generating section 50 as shown in FIG.

In the case of the example shown in FIG.
Represents a plurality (32 in FIG. 6) of shift register elements SR
1 to SR32 and a plurality (three in FIG. 6) of exclusive OR elements ExOR1 to ExOR3, which are PN generators.
Similarly, the shift register elements SR1 to SR32 load the load values A1 to A32 given by the code control unit 20 according to the load command LD given from the code control unit 20, and perform a shift operation by applying a clock (not shown) to spread the spread code. What happens.

Here, when the load values A1 to A32 are changed, the phase of the long-period PN code changes abruptly, as if a different type of PN code were generated.

Although not shown in the code controller 20 (see FIG. 1), the main controller 19 sends load values A1 to A1.
When the selection pattern of A32 is given and the switching of the type of the spread code sequence is instructed from the frame timing generation unit 53, the code control unit 20 sets the next load values A1 to A32 and the load command LD on the selection pattern. Is given to the original spreading code generation section 50, and the type of the spreading code sequence (here, the type having a significantly different phase is also called the different type)
To change.

In the third embodiment, the detailed configuration of the header spreading code generator 17 is the same as the detailed configuration of the spreading code generator 15 shown in FIG. The detailed configuration for generating the spread code and the header spread code excluding the synchronization acquisition configuration of the code estimator 32 and the header spread code estimator 35 is the same as the detailed configuration of the spread code generator 15 shown in FIG. Therefore, illustration and detailed description of the operation are omitted.

According to the third embodiment, as in the first embodiment, the confidentiality can be improved without delaying synchronization pull-in.

Further, according to the third embodiment, it is expected that a configuration for generating a plurality of types of spreading code sequences and a header spreading code sequence can be made simpler than the first and second embodiments. You.

The technical idea that the main control unit directly instructs the switching timing and the like as in the second embodiment,
The embodiment may be configured by combining the technical idea of providing only one original spreading code generator as in the third embodiment and generating a plurality of types of spreading codes and header spreading codes. Of course.

(D) Fourth Embodiment Next, a fourth embodiment in which the spread spectrum communication system and apparatus according to the present invention are applied to a mobile communication system of a multiplex spread CDMA system will be described in detail with reference to the drawings. I do.

Also in the fourth embodiment, if a schematic configuration of a transmission configuration and a reception configuration of a traffic channel is illustrated, it can be represented in FIGS. 1 and 2 according to the above-described first embodiment. Therefore, description of the schematic configuration and operation of the transmission configuration and the reception configuration of the traffic channel is omitted. 1 and 2 are also used in the following description.

The fourth embodiment is different from the first embodiment mainly in that a code table is used as a configuration for changing a code sequence of a spread code and a spread code for a header.

FIG. 7 is a functional block diagram showing a detailed configuration of the spreading code generator 15 in the fourth embodiment. FIG. 8 is an explanatory diagram showing the configuration of the code table unit 56 in FIG.

In FIG. 7, the spread code generator 15 of the fourth embodiment has a frame timing generator 53, a search key generator 54, a table search unit 55, and a code table unit 56.

As shown in FIG. 8, the code table section 56 includes N types of spreading code sequences CODE # 1 to CODE # N.
Is stored. N types of spreading code sequence CO
Different combinations in which DE # 1 to CODE # N are taken out one by one and arranged are switching patterns RND # 1 to RND #
N. For example, the switching pattern RND
# 1 is a spread code sequence CODE # 1, CODE # (N-
3), CODE # 2,..., CODE # 9 in that order.

In the case of the fourth embodiment, each type of stored spreading code sequence CODE # 1,.
The number of bits of N is equal to the number of bits per frame (M bits). Note that each type of spreading code C
If the number of bits of ODE # 1,..., CODE # N is different from the number of bits per frame (M bits), the code conversion unit 52 similar to the first to third embodiments described above.
Is required in the subsequent stage of the table search unit 55.

The frame timing generator 53 according to the fourth embodiment has a built-in counter that counts cyclically from 1 to N, updates the count value at each switching timing of the spread code sequence, and updates the count value (switching value). Pattern RND # j
Is specified to the search key generating unit 54.

In the case of the fourth embodiment, any one of the above-described switching patterns RND # j is shared between the main control unit 19 (see FIG. 1) in the transmission configuration and the main control unit 39 in the reception configuration. The switching pattern RND # j is provided to the search key generator 54 via the code controller 20.

The search key generation unit 54
From the switching pattern RND # j given via the PC and the count value given from the frame timing generator 53 to form information (search key) for causing the code table 56 to search for a spread code sequence, and to search the table. Part 5
Give 5 An encryption or decryption method as described later with reference to FIGS. 11 and 12 may be applied to the generation of the search key.

As a result, table search section 55 stores the spread code sequence corresponding to the search key in code table section 56.
, And is provided to the spread modulation unit 14.

In the fourth embodiment, the detailed configuration of the spreading code generator 17 for the header is the same as the detailed configuration of the spreading code generator 15 shown in FIG. The detailed configuration for generating the spreading code and the header spreading code except for the synchronization acquisition configuration of the code estimating unit 32 and the header spreading code estimating unit 35 is the same as the detailed configuration of the spreading code generating unit 15 shown in FIG. Therefore, illustration and detailed description of the operation are omitted.

According to the fourth embodiment, as in the first embodiment, confidentiality can be enhanced without delaying synchronization pull-in. In particular, if the switching pattern RND # j is also changed during communication by exchanging information using the control channel, the confidentiality can be further enhanced.

Further, according to the fourth embodiment, since the code table is used in the configuration for switching the type of the spread code sequence or the type of the spread code sequence for the header, the configuration is simplified by software processing in many cases. Things.

Hereinafter, the manner of ownership of the code table will be described with reference to a modified embodiment of the fourth embodiment.

In the above description, the base station and the mobile station are fixedly provided with the code table. However, the contents (code table) of the code table may be rewritten. For example, the base station control station or the radio system control station may determine a code table used by the base station and the mobile station and store the code table in the code table section of the base station and the mobile station. In this case, the determination method may be, for example, the area to which the base station belongs, the current time zone, and the mobile station grouped according to the remainder obtained by dividing the identification number of the mobile station by a predetermined value. The code table to be used may be determined. In this case, since the code table to be used is not unique from the viewpoint of a third party, the confidentiality can be further improved.

If the system does not allow the switching pattern RND # j to be changed during communication as code table information at the mobile station, the switching pattern RN
D # j may be owned.

The technical idea that the main control unit directly instructs the switching timing and the like as in the second embodiment,
It is a matter of course that the embodiment may be configured in combination with the technical idea of selecting and generating a plurality of types of spreading codes or header spreading codes using the code table as in the fourth embodiment.

In the above description of the fourth embodiment, the code table 56 stores the spread code itself. However, the spread code is encrypted and stored (encrypted code). As a configuration, for example, FIG.
), A configuration for decrypting the encrypted spread code obtained by the search in the table search unit 55 (see FIG. 14 described later).
May be provided to output the spread code that has been decrypted.

(E) Fifth Embodiment Next, a fifth embodiment in which the spread spectrum communication system and apparatus according to the present invention is applied to a mobile communication system of a multiplex spread CDMA system will be described in detail with reference to the drawings. I do.

Also in the fifth embodiment, if a schematic configuration of a transmission configuration and a reception configuration of a traffic channel is illustrated, it can be represented in FIGS. 1 and 2 according to the first embodiment. Therefore, description of the schematic configuration and operation of the transmission configuration and the reception configuration of the traffic channel is omitted.

In the fifth embodiment, the spread code sequence type switching information transmitted / received for switching the type of the spread code sequence or header spread code sequence between the base station and the mobile station is transmitted / received as it is. Rather, it is characterized in that it is processed and transferred. That is, the fifth embodiment utilizes encryption and encryption / decryption techniques. The specific contents of the spread code sequence type switching information are the same as those of the first type described above.
-It depends on the fourth embodiment. For example, in the case of the fourth embodiment, the content itself of the code table and the switching pattern RND # j correspond.

FIG. 9 is a block diagram showing a processing configuration on the transmitting side of the spreading code sequence type switching information of the base station and the mobile station. FIG. 10 is a block diagram showing the spreading code sequence type of the base station and the mobile station. It is a block diagram which shows the reverse processing structure in the receiving side of switching information.

In FIG. 9, the spreading code sequence type switching information is provided to an encryption unit 60, and is encrypted by the encryption unit 60 to form encrypted spreading code sequence type switching information. The encrypted spreading code sequence type switching information is transmitted to the opposing mobile station or base station via, for example, a control channel. In the case of the fifth embodiment, the encryption method in the encryption unit 60 may be any method using a key.

In the case of the fifth embodiment, the encryption unit 60
Is provided with a common key held in a common key holding unit 61 and a temporarily assigned key held in a temporarily assigned key holding unit 62. The encryption unit 60 identifies the common key and the temporarily assigned key Encryption is performed using a combination (either addition processing or connection processing) as an encryption key.

Here, the common key held in the common key holding unit 61 is common to the entire mobile communication system.

On the other hand, the temporary assignment key held in the temporary assignment key holding section 62 is assigned by, for example, a base station control station or a radio system control station. The assignment timing of the temporary assignment key is arbitrary, and depends on the switching method and timing of the type of the spreading code sequence or the header spreading code sequence. For example, (1) every call connection, (2) every plural frames, (3) In addition, there is a case where the manager (base station control station or radio system control station) determines that it is necessary. When the administrator (base station control station or radio system control station) determines that it is necessary, (1) when a certain time or time zone comes, (2) when traffic becomes tight, (3) This is the case where an abnormal access from a third party is confirmed.
The exchange of the temporarily assigned key is performed by a control channel, that is, (1) an associated control channel of the air interface,
(2) Through the designated time channel of the common control channel of the air interface. Further, the temporary assignment key includes (1) all users (for example, when changing according to the time zone), (2) users who have grouped (as a grouping method, mobile station identification information is divided by a remainder after being divided by a set value),
(3) Users who receive a certain service (such as data communication) and (4) users who are in a certain area may share the service.

A temporary assignment key is assigned to a plurality of users (mobile stations).
This does not cause a problem because the spreading code sequence type switching information exchanged between the base station and the mobile station differs depending on the writing user.

In the mobile station or the base station to which the encrypted spread code sequence type switching information formed by the configuration of FIG. 9 is given from the opposing base station or the mobile station, as shown in FIG. Uses the encryption key determined by the common key held in the common key holding unit 61 and the temporarily assigned key held in the temporarily assigned key holding unit 62 to transmit the encrypted spread code sequence type switching information. It performs encryption / decryption and extracts spreading code sequence type switching information.

According to the fifth embodiment, as in the first embodiment, confidentiality can be improved without delaying synchronization pull-in.

Further, according to the fifth embodiment, the spread code sequence type switching information transmitted and received for switching the type of the spread code sequence or the type of the spread code sequence for the header between the base station and the mobile station is encrypted. Since transmission and reception are performed, and a part of the encryption key is a temporarily assigned key that can be changed, the confidentiality of communication can be improved in this aspect as well.

As a modified example of the fifth embodiment, as shown in FIGS. 11 and 12, a public key for a mobile station or a base station is applied instead of a common key for the entire system. Can be mentioned. In this case, the public key is also different depending on the mobile station and the base station, so that the confidentiality of the communication can be further improved.

(F) Sixth Embodiment Next, a sixth embodiment in which the spread spectrum communication system and apparatus according to the present invention is applied to a mobile communication system of a multiplex spread CDMA system will be described in detail with reference to the drawings. I do.

In the above-described first to fifth embodiments, both the base station and the mobile station have a configuration capable of generating one of a plurality of types of spreading code sequences. On the other hand, the sixth embodiment has a configuration in which only one of the base station and the mobile station can generate any of a plurality of types of spreading code sequences, and switches to the next type with respect to the other. before,
The following type of spreading code sequence is transmitted.

FIG. 13 shows a transmitting side configuration of the next type of spread code sequence, and FIG. 14 shows a receiving side configuration of the next type of spread code sequence.

In FIG. 13, the spreading code generation unit 15
For example, such as having a code table unit shown in FIG.
While the current spread code is being generated, the next type of spread code can be simultaneously generated from another output terminal. The spreading code generator 15 supplies the current spreading code to the spreading modulator 14 (see FIG. 1) (not shown), and the next type of spreading code to the encryption structure. As the encryption configuration, the same configuration (60 to 62) as that of the above-described fifth embodiment can be applied, and the description thereof is omitted. The encrypted spread code thus obtained is transmitted to the opposing mobile station or base station, for example, via a control channel.

In the mobile station or the base station to which such an encrypted spread code is given, a spread code after switching is obtained by the same decryption structure (65 to 67) as in the fifth embodiment. To the spreading code estimation unit 32. The spreading code estimating unit 32 includes, for example, a buffer for buffering the switched spreading code, and when the switching of the type of spreading code sequence is instructed from a timing generator (not shown), the spread code The code is generated from that point.

According to the sixth embodiment, as in the first embodiment, confidentiality can be enhanced without delaying synchronization pull-in.

Further, according to the sixth embodiment, a configuration capable of generating any of a plurality of types of spreading code sequences is provided in one of the base station and the mobile station, and the spreading code itself is transmitted to the other. Therefore, the configuration of one of the base station and the mobile station can be simplified. Although the spread code itself is transmitted / received for code hopping, it is transmitted / received after being encrypted, so that confidentiality is not reduced.

As a modification of the sixth embodiment, as shown in FIGS. 15 and 16, a public key for a mobile station or a base station is applied instead of a common key for the entire system. Can be mentioned.

(G) Seventh Embodiment Next, a seventh embodiment in which the spread spectrum communication system and apparatus according to the present invention are applied to a mobile communication system of a multiplex spread CDMA system will be described in detail with reference to the drawings. I do.

The seventh embodiment is a combination of the above-mentioned new technical idea of code hopping and conventional frequency hopping.

FIG. 17 is a functional block diagram showing a main part of a transmission configuration for a traffic channel of a base station or a mobile station according to the seventh embodiment, which is the same as FIG. The reference numerals are attached. FIG.
Is a functional block diagram showing a main part of a reception configuration corresponding to the transmission configuration of the mobile station or the base station according to the seventh embodiment. The same reference numerals are given to the same and corresponding parts as those in FIG. 2 described above. Is shown.

The two main controllers 19 and 39 also share information for switching the radio frequency band (RF band).
For example, a period in which the same RF band is used is a time for switching a plurality of types of spreading code sequences in time series, and is selected to be an integral multiple of a frame period.

When it is time to change to a new frequency, the main control unit 19 gives the new frequency information to the frequency control unit 70 to instruct switching of the RF band. At this time, the frequency control unit 70 , The carrier frequency from the variable local oscillator in the frequency converter 18 is controlled to be the designated frequency.

On the other hand, when it is time to change to a new frequency, the main control unit 39 of the reception configuration
1, the new frequency information is given, and the switching of the RF band is instructed. At this time, the frequency control unit 71 sets the carrier wave frequency from the variable local oscillator in the frequency conversion unit 30 to the instructed frequency. Control.

The switching between the types of the spreading code sequence and the spreading code sequence for the header is executed as in the above-described embodiments.

As described above, according to the seventh embodiment,
Since the new technical idea of code hopping is combined with the conventional frequency hopping, the confidentiality of communication can be improved more than in the above embodiments.

(H) Eighth Embodiment In each of the embodiments described above, the spread spectrum communication system and apparatus according to the present invention are applied to a mobile communication system of a multiplex spread CDMA system.

The eighth embodiment adopts a general single spreading method instead of the multiple spreading method. In the eighth embodiment, a main part of a transmission configuration for a traffic channel of a base station or a mobile station is shown in a functional block diagram of FIG. 19, and a reception configuration corresponding to the transmission configuration of the mobile station or the base station is shown. The main part is shown in the functional block diagram of FIG. 20, and the function of each part is the same as that of the corresponding element of the first embodiment described above.

According to the eighth embodiment, since code hopping is employed, confidentiality of communication can be improved.

(I) Ninth Embodiment In the ninth embodiment, the above-described code hopping is introduced into a multi-code transmission system for transmitting one piece of user information using a plurality of code channels. Things.

FIG. 21 is a functional block diagram showing a main part of a transmission configuration for a traffic channel of a base station or a mobile station according to the ninth embodiment, which is the same as FIG. The reference numerals are attached. FIG.
Is a functional block diagram showing a main part of a reception configuration corresponding to the transmission configuration of the mobile station or the base station according to the ninth embodiment. The same reference numerals as in FIG. Is shown.

In FIG. 21, the framing unit 11 includes:
The user information destined for the opposing mobile station or base station output by the user information buffer unit (not shown) is provided, and the framing unit 11 divides the user information into a plurality of streams (FIG. 21).
, And the user information of each of the divided sequences is framed, and the A processing units 70-1 to 70-7
Give to 0-3.

Each of the A processing units 70-1,..., 70-3 has, for example, an error correction coding unit, an information modulation unit, a spread modulation unit, and a spread code generation unit as shown in FIG. , And sequentially performs error correction coding, information modulation, and spread modulation on the signal from the framing unit 11 and supplies the signal to the corresponding orthogonal transform units 71-1 to 71-3.

Each orthogonal transform unit 71-1,..., 71-3 is assigned an orthogonal code that is orthogonal to each other, and signals from the corresponding A processing units 70-1,. Is orthogonally transformed using the orthogonal code assigned to itself, and the converted signal is given to the combining unit 72 to be superimposed.

The frequency conversion section 18 up-converts the frequency of the output signal from the synthesis section 72 to a radio frequency band (RF band). The RF signal obtained in this manner is power-amplified by a power amplifier (not shown), and is then given to a shared antenna via a shared antenna (not shown) and radiated to space.

In the case of the ninth embodiment, when the main control unit 19 instructs the switching of the type of the spread code sequence, the code control unit 20 transmits the A processing unit 70-1 for each sequence.
.., The type of the spread code sequence generated for the spread code generator in 70-3 is controlled. here,
The code control unit 20 controls the spreading code generation units in the A processing units 70-1,..., 70-3 for each stream to generate different types of spreading codes in the same period.

Next, the configuration of the receiving side will be described. In FIG. 22, a frequency conversion unit 30 captures a shared transmission / reception antenna (not shown), down-converts an RF band reception signal input to a reception configuration via an antenna shared duplexer (not shown), and converts the signal to a baseband frequency band. The data is converted and supplied to the orthogonal inverse conversion units 75-1 to 75-3.

The orthogonal inverse transform units 75-1,..., 75-3
Are used to transform the corresponding orthogonal transform units 71-1,..., 71
-3, which is the inverse process of the process of -3, and is applied to the corresponding B processing units 76-1,..., 76-3.

Each of the B processing units 76-1,..., 76-3 is composed of, for example, a despreading unit, a spreading code estimating unit, an information demodulating unit, and an error correcting decoding unit as shown in FIG. , 75-3, and sequentially performs despreading, information demodulation, and error correction decoding on the signals from the corresponding inverse orthogonal transform units 75-1,.

The frame disassembling section 38 includes a B processing section 76-
1,..., 76-3 are decomposed respectively, and are multiplexed to assemble and output user information to be transmitted by the opposing base station or mobile station.

In the case of the ninth embodiment, when the main control unit 39 instructs the switching of the type of the spread code sequence, the code control unit 40 transmits the B processing unit 76-1 of each sequence.
,..., The type of the spreading code sequence generated for the spreading code estimating unit in 76-3 is switched. here,
The code control unit 40 controls the spreading code estimation units in the B processing units 76-1,..., 76-3 for each sequence to generate different types of spreading codes in the same period.

According to the ninth embodiment, since code hopping is introduced into a multi-code transmission mobile communication system, communication confidentiality in a multi-code transmission mobile communication system can be improved.

(J) Other Embodiments In the above, the configuration example of the code table is shown in FIG. 8, but it is needless to say that the configuration of the code table is not limited to this. For example, as shown in FIG. 23 (B), identification information CID # j is added to each type of spreading code CODE # j, and the variation pattern RND # i of the type of spreading code sequence is obtained as shown in FIG. As shown in A), the information may be defined by a combination of identification information CID #j.

In each of the embodiments relating to the multiplex spreading method, code hopping is shown for both the normal spreading code sequence and the header spreading code sequence. May be.

Further, in each of the above embodiments, the technical idea of code hopping is applied to the traffic channel. However, code hopping may be applied to other channels.

Furthermore, each of the above embodiments is characterized in that the CDMA
Although the present invention is applied to a mobile communication system of the system, code hopping may be applied to a spread spectrum communication system of one-to-one communication.

[0143]

As described above, according to the present invention, the transmission and reception of a transmission signal body between the first and second spread spectrum communication apparatuses using a spreading code is performed during the communication period. Since the type of spreading code sequence to be applied is changed, the confidentiality of communication can be enhanced without complicating the synchronization acquisition method.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a traffic channel transmission configuration according to a first embodiment.

FIG. 2 is a block diagram illustrating a traffic channel reception configuration according to the first embodiment.

FIG. 3 is a block diagram illustrating a detailed configuration around a spread code generator according to the first embodiment;

FIG. 4 is a block diagram illustrating a detailed configuration around a spread code generation unit according to a second embodiment.

FIG. 5 is a block diagram showing a detailed configuration around a spread code generator according to a third embodiment.

FIG. 6 is a block diagram illustrating a detailed configuration example of an original spreading code generation unit according to a third embodiment.

FIG. 7 is a block diagram illustrating a detailed configuration around a spread code generator according to a fourth embodiment;

FIG. 8 is an explanatory diagram illustrating a configuration example of a code table according to a fourth embodiment.

FIG. 9 is a block diagram illustrating an encryption configuration according to a fifth embodiment.

FIG. 10 is a block diagram illustrating an encryption / decryption configuration according to a fifth embodiment.

FIG. 11 is a block diagram illustrating an encryption configuration according to a modified embodiment of the fifth embodiment.

FIG. 12 is a block diagram showing an encryption / decryption configuration according to a modified embodiment of the fifth embodiment.

FIG. 13 is a block diagram illustrating an encryption configuration according to a sixth embodiment.

FIG. 14 is a block diagram illustrating an encryption / decryption configuration according to a sixth embodiment;

FIG. 15 is a block diagram showing an encryption configuration according to a modified embodiment of the sixth embodiment.

FIG. 16 is a block diagram showing an encryption / decryption configuration according to a modified embodiment of the sixth embodiment.

FIG. 17 is a block diagram illustrating a traffic channel transmission configuration according to a seventh embodiment.

FIG. 18 is a block diagram illustrating a traffic channel reception configuration according to a seventh embodiment.

FIG. 19 is a block diagram illustrating a traffic channel transmission configuration according to an eighth embodiment.

FIG. 20 is a block diagram illustrating a traffic channel reception configuration according to an eighth embodiment.

FIG. 21 is a block diagram illustrating a traffic channel transmission configuration according to a ninth embodiment.

FIG. 22 is a block diagram illustrating a traffic channel reception configuration according to a ninth embodiment.

FIG. 23 is an explanatory diagram showing another configuration example of the code table.

[Explanation of symbols]

14: Spread modulator, 15: Spread code generator, 16: Header addition unit, 17: Spread code generator for header, 18: Frequency converter, 19: Main controller, 20: Code controller, 30
... frequency conversion unit, 31 ... despreading unit, 32 ... spreading code estimation unit, 34 ... header despreading unit, 35 ... header spreading code estimation unit, 39 ... main control unit, 40 ... code control unit, 50, 5
0-1 to 50-N: original spreading code generator, 51: selection switch, 52: code converter, 53: frame timing generator, 54: search key generator, 55: table search unit, 56: code table unit , 60 ... encryption unit, 61,
66 common key holding unit, 61a ... partner public key holding unit, 6
6a: Self-public key holding unit, 62, 67: Temporarily assigned key holding unit, 70: Frequency control unit, 71: Frequency control unit.

Claims (14)

[Claims] 1. A spread spectrum communication system for transmitting and receiving a transmission signal body by using a spreading code between a first and a second spread spectrum communication device, wherein the first and second spread spectrum communication devices A type of spreading code sequence to be applied during communication in the communication. 2. The spread spectrum communication system according to claim 1, wherein the change of the type of the spread code sequence is executed at predetermined intervals. 3. The spread spectrum communication system according to claim 1, wherein the type of said spread code sequence is changed irregularly according to a communication situation. 4. The spread spectrum communication system according to claim 1, wherein a propagation path frequency is also changed during communication between said first and second spread spectrum communication apparatuses. . 5. The method according to claim 1, wherein the change pattern of the type of the spread code sequence is transmitted and received between the first and second spread spectrum communication devices before the transmission signal body communicates. The spread spectrum communication method according to claim 1. 6. The first type of the spread code sequence after the change or the spread code sequence after the change is transmitted by the first channel during communication of the transmission signal main body through a channel different from the communication channel of the transmission signal main body. 5. The spread spectrum communication system according to claim 1, wherein said second spread spectrum communication device supplies said second spread spectrum communication device to said second spread spectrum communication device. 7. The first and / or second spread spectrum communication apparatus encrypts and holds the spread code sequence or information for specifying the spread code sequence, and decrypts and generates a spread code. The spread spectrum communication system according to any one of claims 1 to 6. 8. The method according to claim 1, wherein information to be exchanged between the first and second spread spectrum communication apparatuses for switching the type of the spread code sequence is encrypted and transmitted. The spread spectrum communication method described in 1. 9. The spread spectrum communication system according to claim 7, wherein the encryption keys used in the encryption and decryption are a common key and a one-time allocation key. 10. An encryption key used in the encryption and decryption is a device key fixedly assigned to one of the first and second spread spectrum communication devices and a temporarily assigned key. The spread spectrum communication method according to claim 7 or 8, wherein: 11. When there are a plurality of said second spread-spectrum communication devices communicating with said first spread-spectrum communication device, switching of the type of said spread code sequence is performed for all of said second spread-spectrum communication devices. The spread spectrum communication method according to any one of claims 1 to 10, wherein: 12. When there are a plurality of said second spread spectrum communication apparatuses communicating with said first spread spectrum communication apparatus, a plurality of said second spread spectrum communication apparatuses are grouped and belong to the same group. The spread spectrum communication method according to any one of claims 1 to 11, wherein, in communication with the second spread spectrum communication apparatus, a plurality of types of the spread code sequences that can be used as switching targets are the same. 13. A spread spectrum communication apparatus comprising: a spread code generating means for generating a spread code; and a spread modulation means for spreading a transmission signal body using the spread code from the spread code generating means. A spread code sequence type change control unit that changes a type of a spread code sequence generated by the spread code generation unit in a period during transmission of the transmission signal body based on an agreement with a communication device. Spreading communication device. 14. A spread code estimating means for estimating a spread code phase in a received signal to generate a spread code, and a despreading means for despreading the received signal using a spread code from the spread code estimating means. In a spread spectrum communication apparatus, based on an agreement with an opposite spread spectrum communication apparatus, a spread code sequence type change control for changing a type of a spread code sequence generated by the spread code estimating means during a reception period of the received signal. A spread spectrum communication device comprising: