JP2010219877A - Wireless communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication system for easily capturing synchronism in a receiving apparatus, and communication method therefor. <P>SOLUTION: A wireless communication system for performing wireless communication according to a code division multiple access system includes: a transmitting apparatus for transmitting a radio wave by performing spread modulation on data containing synchronizing detection information and data information; and a receiving apparatus for receiving the radio wave and performing spread demodulation on the spread-modulated data to obtain the synchronizing detection information and the data information. The transmitting apparatus transmits the synchronizing detection information in the system monopolistically and transmits the data information after the lapse of a prescribed non-communication time from the transmission of the synchronizing detection information. When prescribed data are detected from the synchronizing detection information, the receiver determines data, which are received after the lapse of the non-communication time from reception of the synchronizing detection information, as data information and performs spread demodulation on the data information using the same spreading code as a spreading code used for spread demodulation of the synchronizing detection information. Thus, the receiving apparatus can easily capture synchronism of data. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a communication method, a communication program, and a wireless communication system in a wireless network, and more particularly, to synchronization acquisition in a wireless communication system that performs code division multiple access (CDMA).

  Conventionally, an apparatus that performs communication using CDMA has been proposed. CDMA is a scheme that enables multiple access by spreading narrowband modulated signals, and is used in, for example, mobile phones, GPS (Global Positioning System), wireless LAN (Local Area Network), and the like.

  CDMA modulates a signal to be transmitted by applying a spreading code sequence having a higher transmission rate than the signal, thereby spreading the signal frequency band to a wider band than the original bandwidth and transmitting the signal. On the receiving side, the original signal can be restored by demodulating the received signal using a despread code sequence correlated with the spreading code.

  Therefore, when multiple communication devices transmit signals at the same time, if the signals are spread using different spreading codes for each transmission device, the receiving side will receive each signal correctly even if those signals interfere. can do. When CDMA communication is performed between mobile stations, for example, the base station manages the spreading codes used by the mobile stations so that each mobile station can communicate using different spreading codes.

  For example, in a communication system in which four spreading codes can be used, four terminals can transmit data at an arbitrary timing at the same time. Also, the use efficiency of spreading codes can be increased by adopting an arbitrary access control method (TDMA: Time Division Multiple Access) by time division and performing data transmission timing control.

Japanese Patent Laid-Open No. 11-32007 JP-A-7-222227

  However, a conventional communication system using CDMA cannot secure sufficient performance in the synchronization processing of spreading code sequences. In the spread spectrum demodulation at the receiver, it is necessary to synchronize the spread code sequence and the despread code sequence. The correlation value between the spread code and the despread code is calculated using the preamble portion of the received data, and the correlation value is calculated. The synchronization point is detected by obtaining the peak. If multiple data are received at the same time, if the reception timings of the preamble parts of all the data match, a periodic peak can be obtained in the calculation of the correlation value, and therefore the synchronization point of both can be detected. it can. However, if the reception timings of the preamble parts do not match, it is not possible to obtain a periodic peak, and therefore it is not possible to detect a synchronization point.

  In an actual propagation environment, radio waves are affected by reflection and diffraction by various obstacles, and therefore it is impossible to receive a plurality of data in a state where the preamble reception timing and phase rotation are completely matched. Therefore, system performance degradation caused by synchronization acquisition has always been a problem for a wireless communication system using CDMA, and the conventional method cannot be sufficiently satisfied as a technology for solving such a problem. I couldn't.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a system that can sufficiently perform synchronization acquisition at a receiving terminal even when a plurality of transmitting terminals simultaneously transmit data in a CDMA communication system.

  In order to achieve such an object, the wireless communication system of the present invention includes a transmission device that spreads and modulates data including the first data and the second data by wireless radio waves, and the transmission device includes: The wireless communication system of the present invention comprises transmission timing control means for controlling the first data to be transmitted exclusively and the second data to be transmitted after a predetermined time has elapsed since the first data was transmitted. In addition, it includes a receiving device that receives radio waves and spread-demodulates spread-modulated data, and this receiving device determines that predetermined information is detected from the spread-demodulated data as first data Then, data received after a predetermined time has elapsed since the reception of the first data is determined as the second data, and the same despreading code as the despreading code used for the spread demodulation of the first data is used. Second Characterized by spread demodulation data.

  According to the present invention, since the first data required for synchronization acquisition is received without receiving interference from other data, synchronization acquisition can be easily performed. In addition, since the second data is transmitted after a lapse of a certain time since the transmission of the first data, the data necessary for the synchronization acquisition of other packets can be transmitted exclusively during the certain time. .

It is a block diagram which shows the structure of the Example of the transmitter applied to the radio | wireless communications system of this invention. It is a block diagram which shows the structure of the receiver in the Example. It is a schematic diagram which shows the radio | wireless communications system in the Example. It is a figure which shows the structure of the packet produced | generated with the transmitter shown in FIG. It is a figure explaining the no-communication time in the Example. It is a figure which shows an example of the no-communication time management table utilized with the radio | wireless communications system in the Example. It is a figure which shows the transmission method of the packet using the spreading code of the no-communication time management table shown in FIG. It is a timing chart explaining the time division control method in the radio | wireless communications system of the Example. It is a timing chart which shows the transmission timing of the packet in the transmitter shown in FIG. It is a figure which shows the time division control method in the radio | wireless communications system of this invention using a time allocation management table.

  Next, embodiments of a wireless communication apparatus and a wireless network system according to the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 show configurations of embodiments of a transmitter and a receiver applied to a wireless communication apparatus according to the present invention. The transmitter 10 and the receiver 100 are applied to, for example, the radio network system 200 shown in FIG. 3, which includes a base station 202 and a plurality of mobile terminals 204, 206, 208 using the transmitter and receiver according to the present invention. And 210, the base station and the mobile terminal communicate data packets wirelessly. FIG. 4 shows an example of a configuration of a data packet communicated in the system 200, and the packet 300 includes a preamble 302, a unique word 304, a header 306, and application data 308.

  The transmitter 10 of this embodiment generates a packet 300 and transmits it wirelessly, and includes a preamble generation unit 14, a unique word generation unit 16, a modulation unit 18, a spread processing unit 20, a header generation unit 22, and application data generation. Each unit includes a function unit 24, a modulation unit 26, a spread processing unit 28, a spread code management unit 30, a transmission timing control unit 32, and a transmission RF (Radio Frequency) unit 34. It should be noted that elements not directly related to the understanding of the present invention are omitted and redundant description is avoided. Also, the signal is indicated by the reference number of the connecting line that appears.

  The preamble generation unit 14 generates a data string 36 of the preamble 302 and passes it to the modulation unit 18. The data string 36 is a continuous data string having a predetermined pattern of 0 and 1, and is used for synchronization acquisition in the receiver 200.

  The unique word generation unit 16 generates a data string 38 of the unique word 304 and passes the data string 38 to the modulation unit 18. The data string 38 is also a continuous data string having a predetermined pattern of 0 and 1, and is used for recognizing the start of the header 306 and application data 308 in the receiver 200 in this embodiment. In this embodiment, the unique word varies depending on the spreading code used for spreading the packet 300, but the same unique word may be used for all packets. In the following description, the preamble 302 and the unique word 304 are collectively referred to as synchronization detection information 310 for convenience.

  The modulation unit 18 performs primary modulation on a data sequence including the preamble data sequence 36 and the unique word data sequence 38 by a predetermined method to generate a symbol sequence 40 and passes it to the spread processing unit 20.

  The header generation unit 22 generates the data string 42 of the header 306 and passes it to the modulation unit 26. The header data string 42 is a data string composed of fields according to a predetermined format, and is used for communication control and the like.

  The application data generation unit 24 generates a data string 44 of the application data 308 and passes it to the modulation unit 26. In the following description, the header and application data are collectively referred to as data information 312 for convenience.

  The modulation unit 26 performs primary modulation on a data sequence including the header data sequence 42 and the application data sequence 44 by a predetermined method to generate a symbol sequence 46 and passes it to the spread processing unit 28. In the transmitter 10 according to the present embodiment, the modulation detection information 310 and the data information 312 are modulated by different modulation units 18 and 26, but may be performed by any one of the modulation units.

  The spread code management unit 30 determines the spread code 48 used for the spread modulation of the symbol sequences 40 and 46, and passes it to the spread processing units 20 and 28. The spreading code only needs to be determined so that different spreading codes are used between transmitters that transmit simultaneously. In this embodiment, the spreading code is determined for each terminal, but is determined for each communication by a time table or external input. Also good.

  Further, the spreading code management unit 30 of this embodiment holds a value of no communication time used for packet transmission timing control, and searches for the value 50 of the no communication time 314 corresponding to the spreading code 48. To the transmission timing control unit 32.

  Here, the no-communication time is the time from when the synchronization detection information is transmitted until the transmission of data information is started. In the case of the packet 300, the synchronization detection information 310 is first transmitted as shown in FIG. When the no-communication time 314 elapses, transmission of the data information 312 is started. In the present embodiment, the no-communication time is determined for each spreading code by the no-communication time management table of the wireless communication system 200.

  FIG. 6 shows a no-communication time management table used in the communication system of this embodiment. The no-communication time management table 52 stores spreading codes 1, 2, 3 and 4 and the corresponding values of no-communication times 53, 54, 55 and 56. The no-communication times 53, 54, 55 and 56 are 100 μsec, 70 μsec, 40 μsec and 10 μsec, respectively.

  Referring to FIG. 7, a method for transmitting packets 58, 60, 62 and 64 spread using spreading codes 1 to 4 will be described. Since the packet 58 is spread and modulated using the spread code 1, transmission of the data information 68 is started 100 μsec after the synchronization detection information 66 is transmitted. Similarly, in the packet 60 using the spread code 2, transmission of the data information 72 is started 70 μsec after the synchronization detection information 70 is transmitted. In the packet 62 using the spread code 3, transmission of the data information 76 is started 40 μsec after the synchronization detection information 74 is transmitted. In the packet 64 using the spread code 4, transmission of the data information 80 is started 10 μsec after the synchronization detection information 78 is transmitted.

  The spread processing unit 20 performs spread modulation on the symbol sequence 40 received from the modulation unit 18 using the spread code sequence 48 to generate a chip sequence 82. The spread processing unit 20 passes the chip array 82 to the transmission timing control unit 32.

  The spread processing unit 28 performs spread modulation on the symbol sequence 46 received from the modulation unit 26 using the spread code sequence 48 to generate a chip sequence 84. The spread processing unit 28 passes the chip array 84 to the transmission timing control unit 32.

  The transmission timing control unit 32 temporarily stores the chip sequences 82 and 84 received from the spreading processing units 20 and 28 in a buffer, and passes the chip sequence 82 or 84 to the transmission unit RF unit 34 at the timing of each transmission. is there.

  The transmission timing control method in the transmission timing control unit 32 will be described in detail with reference to FIGS. The system 200 in this embodiment implements an arbitrary access control method by time division, and a period divided by time division is called a slot. In the system 200, as shown in FIG. 8, one packet can be communicated for each spreading code in each of the slots S1 and S2.

  The transmission timing of the synchronization detection information and data information in each slot will be described with reference to FIG. In the example shown in FIG. 9, the packets 58, 60, 62, and 64 using the spread codes 1 to 4 are transmitted in the slot S1, but the synchronization detection information 66, 70, 74, and 78 of each packet is the timing. Are transmitted so as not to interfere with each other. In this embodiment, even when a plurality of packets are transmitted in the same slot as described above, the synchronization detection information of each packet is controlled exclusively, that is, transmitted without interfering with other packets.

  In the present embodiment, the transmission timing of synchronization detection information is controlled by dividing each slot into a period during which only packets using a predetermined spreading code can be transmitted and a period during which all packets can be transmitted. .

  Specifically, the slot S1 in FIG. 9 is divided into periods T1, T2, T3, T4, and T5. The synchronization detection information 66 of the packet 58 using the spread code 1 is used in the period T1, and the spread code 2 is used in the period T2. The synchronization detection information 70 of the received packet 60, the synchronization detection information 74 of the packet 62 using the spread code 3 in the period T3, and the synchronization detection information 78 of the packet 64 using the spread code 4 are transmitted exclusively in the period T4. be able to. In the period T5, the data information 68, 72, 76 and 80 of all packets can be transmitted. Other slots are similarly divided.

  Therefore, the transmission timing control unit 32 controls the transmission timing of the synchronization detection information 310 and the data information 312 according to the spread code 48. For example, when the spread code 48 is the spread code 1, the synchronization detection information 310 is transmitted in the period T1, and the data information 312 is transmitted in the period T5 after the no-communication time 53 after transmitting the synchronization detection information 310. Control.

  The transmission RF unit 34 converts the chip arrays 82 and 84 received from the transmission timing control unit 32 into, for example, high-frequency radio frequency signals, and converts them into radio waves 86 and 88, respectively, for transmission.

  Here, an example of the transmission operation of the transmitter 10 in the present embodiment will be described.

  The preamble generator 14 generates a preamble data string 36, and the unique word generator 16 generates a unique word data string 38, both of which are passed to the modulator 18.

  In the modulation unit 18, the data sequences 36 and 38 are modulated to generate a symbol sequence 40. The symbol sequence 40 is sent to the diffusion processing unit 20.

  In the spreading processing unit 20, the symbol sequence 40 is spread using the spreading code 48 given from the spreading code managing unit 30, and a chip sequence 82 is generated. The chip array 82 is sent to the transmission timing control unit 32 and held until the transmission timing is reached.

  The header generation unit 22 generates a header data string 42, and the application data generation unit 24 generates application data data 44, both of which are sent to the modulation unit 26.

  In the modulation unit 26, the data sequences 42 and 44 are modulated to generate a symbol sequence 46. The symbol string 46 is sent to the diffusion processing unit 28.

  In the spreading processing unit 28, the symbol sequence 46 is spread with the spreading code 48 given from the spreading code managing unit 30, and a chip sequence 84 is generated. The chip sequence 84 is sent to the transmission timing control unit 32 and held until a predetermined transmission timing corresponding to the spread code 48 is reached.

  When it is time for the packet spread by the spread code 48 to be transmitted exclusively, the chip sequence 82 is sent to the transmission RF unit 34, converted into a radio wave 86 by the transmission RF unit 34, and transmitted. The chip array 84 is also sent to the transmission RF unit 34 at a predetermined timing based on the no-communication time 314, converted into the radio wave 88 by the transmission RF unit 34, and the no-communication time corresponding to the spread code 48 after the radio wave 86 is transmitted. Sent after 314.

  Next, the configuration of the receiver 100 according to the present embodiment will be described with reference to FIG. The receiver 100 receives radio waves transmitted from the transmitter 10, and includes a reception RF unit 102, a reception timing control unit 104, a despreading code management unit 106, a despreading processing unit 108, a demodulation unit 110, a unique unit A word detection unit 112, a despreading processing unit 114, a demodulation unit 116, and a packet analysis unit 118 are included.

  The reception RF unit 102 receives the radio waves 86 and 88 and converts them into the chip arrays 120 and 122, respectively. In the present embodiment, the receiver 100 first receives the radio wave 86 of the synchronization detection information 310 and receives the radio wave 88 of the data information 312 after a no-communication time 314 after receiving the radio wave 86. The radio wave conversion method may be a known method.

  The reception timing control unit 104 determines whether the chip sequence received from the reception RF unit 102 is a chip sequence of synchronization detection information or a chip sequence of data information. If it is a chip sequence of data information, the data is transferred to the despreading processing unit 114. In this embodiment, the reception timing control unit 104 passes the chip sequence 120 to the despreading processing unit 108 and the chip sequence 122 to the despreading processing unit 114.

  In this embodiment, the reception timing control unit 104 determines the chip sequence by determining whether the reception timing is set for the chip sequence received from the reception RF unit 102. In this embodiment, in the present embodiment, when a unique word is detected from a certain chip sequence in the subsequent processing, this chip sequence is used to measure the timing of receiving data information of the same packet as the packet of this chip sequence. For example, the determination of the chip sequence may be performed based on the time when the radio wave of the chip sequence is received by the receiver 100.

  In the present embodiment, when the unique word 304 is detected from the chip sequence 120, the reception timing of the data information 312 is set, whereby the chip sequence 122 of the data information 312 can be passed to the despreading processing unit 114. In this embodiment, since the data information 312 is received after the no-communication time 314 after the synchronization detection information 310 is received, the data information 312 is based on the despread code used for the spread demodulation of the chip sequence 120. Reception timing can be determined.

  A despreading code management unit 106 holds a despreading code used for communication in the system 200 and passes the despreading code to the despreading processing unit 108. The despread code passed from the despread code management unit 106 to the despread processing unit 108 includes a despread code 124 having a correlation with the spread code 48.

  Further, the despread code management unit 106 holds the value of the no-communication time corresponding to each despread code, and when the unique word 304 is detected from the chip sequence 120, the no-communication time 314 corresponding to the spread code 124. The value 126 is retrieved and passed to the reception timing control unit 104. The reception timing control unit 104 sets the reception timing of the data information 312 based on this value 126. Further, the despreading code management unit 106 stores that the chip sequence 120 passed to the despreading processing unit 108 has been despread using the spreading code 124, and converts the spreading code 124 to the despreading processing unit 114 as necessary. To pass.

  The despreading processing unit 108 performs spread demodulation on the chip sequence 120 received from the reception timing control unit 104 using the despreading code 124 received from the despreading code management unit 106. Spreading demodulation may be performed by a known method, and the despreading processing unit 108 detects the peak of the correlation value between the spread code 48 and the despread code 124 and synchronizes with a predetermined method to generate the symbol sequence 128. To the demodulator 110.

  In this embodiment, the despreading processing unit 108 discovers that the spreading code 124 correlates with the spreading code 48 by sequentially using a plurality of despreading codes held by the despreading code managing unit 106 for the despreading process. Alternatively, the despread code management unit 106 may select the spread code 124 and pass it to the despread processing unit 108 according to the time zone when the radio wave 86 is received.

  The demodulating unit 110 demodulates the symbol sequence 128 received from the despreading processing unit 108 by a predetermined method to generate a data sequence 130 and passes it to the unique word detecting unit 112.

  The unique word detection unit 112 detects the unique word 304 from the data string 130 received from the demodulation unit 110. The unique word may be detected by a known method. In this embodiment, the unique word detection unit 112 holds the reference unique word and detects the unique word 304 by comparing the unique word pattern of the data string 130 with the reference unique word pattern. If the patterns match, the unique word detection unit 130 passes the unique word detection notification 132 notifying the reception timing control unit 104 that the unique word 304 has been detected, and despreading to the despread code management unit 106. The information 134 of the code | symbol 124 is passed.

  In this embodiment, since the unique word is different for each spreading code, the information 134 is obtained from the unique word 304, and the despreading code management unit 106 uses the despreading code 124 for spreading demodulation of the chip sequence 120 based on the information 134. I can know that. For example, if the same unique word is used for all packets, and information on the despreading code cannot be obtained from the unique word, the information 134 may be obtained from the despreading processing unit 108, or the radio wave 86 It may be specified that the despreading code of the chip sequence 120 is the despreading code 124 from the time of receiving the check.

  The despreading processing unit 114 despreads the chip sequence 122 received from the reception timing control unit 104 to generate a symbol sequence 136 and passes it to the demodulation unit 116. In this embodiment, the despreading processing unit 114 determines from the reception timing unit 104 that the chip sequence 122 belongs to the same packet as the chip sequence 120, and from the despreading code management unit 106 to the same despreading code 124 as the chip sequence 120. Receive. The determination of the chip sequence may be performed, for example, by adding the information of the chip sequence 120 to the chip sequence 122 in the reception timing control unit 104. If the unique word is different for each transmitter, the chip sequence is determined from the header 306. It may be determined that columns 122 and 120 belong to the same packet.

  The demodulating unit 116 demodulates the symbol sequence 136 received from the despreading processing unit 114 by a predetermined method to generate a data sequence 138 and passes it to the packet analysis unit 118.

  The packet analysis unit 118 detects and analyzes the header 306 and application data 308 from the data sequence 138 by a predetermined method.

  Here, an example of the reception operation of the receiver will be described.

  In this embodiment, first, a radio wave 86 is received by the receiver 100, and the radio wave 86 is converted into a chip array 120 by the reception RF unit 102 and passed to the reception timing control unit 104.

  The reception timing control unit 104 determines whether or not the reception timing is set for the chip array 120, and the chip array 120 is transferred to the despreading processing unit 108.

  In the despreading processing unit 108, the chip sequence 120 is converted into a symbol sequence 128 and passed to the demodulation unit 110.

  In the demodulator 110, the symbol string 128 is converted into a data string 130, and the data string 130 is passed to the unique word detector 112.

  The unique word detection unit 112 detects the unique word 304. When the unique word 304 is detected, the unique timing detection notification 132 is passed to the reception timing control unit 104, and the information 134 of the despread code 124 is passed to the despread code management unit 106.

  Based on the spread code information 134, the despread code management unit 106 searches for the value 126 of the no-communication time 314 corresponding to the spread code 48 correlated with the despread code 124, and passes the value 126 to the reception timing control unit 104. It is.

  The reception timing control unit 104 sets and measures the reception timing of the radio wave 88 based on the unique word detection notification 132 and the no-communication time value 126.

  When the radio wave 88 is received by the receiver 100, the radio wave 88 is passed to the reception RF unit, converted into a chip row, and passed to the reception timing control unit 104.

  The reception timing control unit 104 determines whether or not the reception timing is set for the chip sequence 122, and the chip sequence 122 is passed to the despreading processing unit 114 together with information about the chip 120.

  In the despreading code processing unit 114, the chip sequence 122 is despread with the same despreading code 124 as the spreading code used for despreading the chip sequence 120 and converted into the symbol sequence 136, and the symbol sequence 136 is sent to the demodulation unit 116. Passed.

  In demodulator 116, symbol sequence 136 is converted to data sequence 138 and passed to packet analyzer 118.

  The packet analysis unit 118 analyzes the header 306 and the application data 308.

  When terminals participating in the wireless communication network are determined, for example, by assigning a slot that can be transmitted to each terminal and a spreading code that can be used in each slot by a time allocation table or the like, a plurality of terminals in the same slot are allocated. May be controlled not to use the same spreading code. In the example shown in FIG. 10, a time allocation table is determined for five consecutive slots, and each terminal periodically transmits data according to this time allocation table. For example, the cycle C1 includes slots S1, S2, S3, S4, and S5, and the terminal 1 can perform data transmission using the spread code 1 in the first slot S1 of the cycle C1. The terminal 1 can similarly perform data transmission using the spread code 1 in the first slot S6 of the next cycle C2.

  Further, when the number of terminals participating in the wireless communication network increases or decreases, the terminals newly added to the system autonomously determine transmission slots and available spreading codes based on the time allocation table and transmit May be.

  Each terminal may determine a transmittable slot and an available spreading code by receiving data transmitted by another terminal. Each terminal may select an available slot and spreading code according to an arbitrary algorithm or randomly.

  For example, by receiving transmission data from a neighboring terminal, after confirming the transmission status of the neighboring terminal, the available slots and spreading codes are determined according to an arbitrary algorithm, or transmission is performed by selecting at random. You may go.

  Also, if the time allocation of slots and spreading codes is periodic, a terminal newly joining the network autonomously determines unused slots and spreading codes by checking the neighboring transmission status for a certain period of time. May be used.

  Also, a management device that manages time allocation may be provided, and each terminal may communicate according to a time allocation table that is periodically sent from the time allocation management device.

  Alternatively, if all terminals can synchronize using GPS or the like, for example, the packet transmission end time information is added to the header portion of the packet, and the packet transmission end time is determined from this information. Thus, the reception start time of the next packet may be determined.

10 Transmitter
30 Spreading code manager
32 Transmission timing controller
100 receiver
104 Reception timing controller
106 Despreading code manager

Claims (8)

Data including first data and second data including predetermined information is spread-modulated and transmitted to the receiving side by radio waves, and the receiving side receives the radio waves and performs the spread-modulated data. In a wireless transmission device that performs wireless communication by a code division multiple access method to obtain first and second data by spreading demodulation
The transmission device includes transmission timing control means for controlling the transmission timing of the first and second data,
The transmission timing control means controls that the first data is transmitted exclusively in the wireless communication system, and the second data is transmitted after a predetermined time has elapsed since the first data was transmitted. A wireless transmission device.   The radio transmission apparatus according to claim 1, wherein the transmission timing and the predetermined time are determined by a spreading code used for spreading modulation of the first and second data. A transmitter that spreads and modulates data including first data including predetermined information and second data and transmits the data by radio waves;
In a wireless communication system that performs wireless communication by a code division multiple access method, including a receiving device that receives the wireless radio wave and spreads and demodulates the spread modulated data to obtain first and second data,
The transmission device includes transmission timing control means for controlling transmission timing of the first and second data,
The transmission timing control means controls the first data to be transmitted exclusively in the wireless communication system, and the second data is transmitted after a predetermined time has elapsed since the first data was transmitted,
The spread demodulation means of the receiving device performs spread demodulation on the received data and determines that the predetermined information is detected when the predetermined information is detected, and receives the first data after receiving the first data. A radio characterized in that data received after a lapse of time is determined as second data, and the second data is spread and demodulated using the same spreading code as the spreading code used for spreading and demodulating the first data Communications system.   4. The wireless communication system according to claim 3, wherein the system includes time division control means, and the transmission apparatus transmits first and second data in each divided period.   4. The wireless communication system according to claim 3, wherein the system pre-allocates a period during which data can be transmitted and a spreading code that can be used during the period to the transmitting apparatus.   6. The wireless communication system according to claim 5, wherein the period during which data can be transmitted and the available spreading codes are determined by a time table.   A transmission timing control program for causing a computer to realize the transmission timing control means according to claim 1 as its function.   A reception timing control program for causing a computer to realize the spread demodulation means according to claim 3 as its function.

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