WO2015159627A1 - Wireless communication system and data transmission device used in wireless communication system - Google Patents

Wireless communication system and data transmission device used in wireless communication system Download PDF

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WO2015159627A1
WO2015159627A1 PCT/JP2015/057788 JP2015057788W WO2015159627A1 WO 2015159627 A1 WO2015159627 A1 WO 2015159627A1 JP 2015057788 W JP2015057788 W JP 2015057788W WO 2015159627 A1 WO2015159627 A1 WO 2015159627A1
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data
spread spectrum
signal
data transmission
communication system
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French (fr)
Japanese (ja)
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井上　学
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株式会社村田製作所
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/16—Code allocation
    • H04J13/18—Allocation of orthogonal codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/06—Optimizing the usage of the radio link, e.g. header compression, information sizing, discarding information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/16—Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
    • H04W4/04—
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation

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  • the present invention relates to a wireless communication system having a data transmission device that transmits a signal subjected to spread spectrum modulation and a data reception device that receives a signal transmitted from the data transmission device.
  • a mobile communication system in which a base station apparatus and a plurality of mobile station apparatuses are connected by the DS-CDMA system is disclosed in Patent Document 1 below.
  • a signal transmitted from each mobile station apparatus to a base station apparatus is composed of a plurality of information units.
  • the first information unit is spread spectrum modulated with a system-wide spreading code.
  • the information units subsequent to the second information unit following the first information unit are subjected to spread spectrum modulation with a different spreading code for each mobile station apparatus.
  • the spreading code used for the spread spectrum of the information units subsequent to the second information unit may be assigned to each mobile station device in advance, or commanded from the base station device after transmitting the first information unit. You may do it.
  • a competition occurs between a plurality of mobile station apparatuses only when the transmission times of the first information units using a common spreading code overlap.
  • the transmission time of the first information unit is sufficiently shorter than the transmission times of all information units. This reduces the probability of access contention.
  • a communication system is constructed in which data is transferred in the uplink direction from a plurality of data transmission apparatuses to one data reception apparatus, but data is not transferred in the reverse downlink direction.
  • Such a communication system is applied, for example, to an application in which measurement results acquired by sensors such as temperature sensors installed at a large number of measurement points are transmitted to a management center.
  • a data transmission device is installed at each measurement point, and a data reception device is installed at the management center.
  • a spread spectrum communication system is an example of a communication system that is resistant to noise.
  • a data transmission device performs spread spectrum modulation on transmission data using a spread code
  • a data reception device demodulates a received signal using the same spread code.
  • the demodulation processing routine is switched in accordance with the spreading code used for the received signal.
  • the number of spreading codes to be used increases as the number of data transmission devices increases. As the number of spreading codes increases, the burden of switching the demodulation processing routine according to the spreading code increases in the data receiving apparatus.
  • the data transmission apparatus In the method of instructing the spreading code used in the data transmission apparatus from the data reception apparatus to the data transmission apparatus for each series of communications, the data transmission apparatus must have a signal reception function. Giving the data transmission device a reception function leads to an increase in power consumption and cost of the data transmission device.
  • An object of the present invention is to suppress the increase in the number of demodulation processing routines in the receiving apparatus without giving the signal receiving function to the data transmission apparatus of the spread spectrum communication method, and the probability of occurrence of a signal collision that cannot be demodulated. It is an object of the present invention to provide a radio communication system capable of suppressing an increase in the frequency.
  • a plurality of data transmission devices for transmitting signals;
  • a data receiving device that receives the signals transmitted from a plurality of the data transmitting devices,
  • the signal transmitted from each of the data transmission devices has a frame format in which a plurality of data units, which are units for performing spread spectrum modulation using a spreading code, are arranged on the time axis, and within one frame format
  • the data units adjacent to each other are spread spectrum modulated using spreading codes orthogonal to each other,
  • the number of the data units included in one frame format is the same in a plurality of the data transmission devices,
  • There is provided a communication system in which the data units at corresponding positions in the frame format of the signals transmitted from a plurality of the data transmission devices are subjected to spread spectrum modulation using the same spreading code.
  • the probability of occurrence of signal collision that cannot be demodulated by the data receiving apparatus is reduced. Since there is no need to instruct a spreading code to be used from the data receiving apparatus to the data transmitting apparatus, it is not necessary for the data transmitting apparatus to have a signal receiving function. Further, even if the number of data transmission devices increases, it is not necessary to increase the number of spreading codes to be used.
  • the spread codes used for spread spectrum modulation of a plurality of the data units in one frame format may be different and orthogonal to each other. As a result, the probability of signal collision that cannot be demodulated by the data receiving apparatus is further reduced.
  • the data transmitting device may have a function of transmitting the signal, but may not have a function of receiving a signal from the data receiving device. Thereby, it is possible to avoid an increase in power consumption and an increase in cost of the data transmission apparatus.
  • a plurality of the data transmission devices may be configured to transmit the signals independently of each other.
  • a carrier generation unit for generating a carrier;
  • a spread spectrum modulation section for generating a modulation signal;
  • a modulation unit that modulates the carrier wave based on the modulation signal;
  • An antenna for transmitting the signal modulated by the modulation unit to a data receiving device;
  • the modulation signal has a frame format in which a plurality of data units serving as units for performing spread spectrum modulation using a spreading code are arranged on a time axis, and the data units adjacent to each other in one frame format are:
  • a data transmission apparatus that is spread spectrum modulated using spreading codes that are orthogonal to each other.
  • data units adjacent to each other in one frame format are spread spectrum modulated using spreading codes orthogonal to each other, even if signals are randomly transmitted from a plurality of data transmission apparatuses, they cannot be demodulated. The probability of signal collision occurrence is reduced. Since the spreading code can be fixedly set in the data transmitting apparatus in advance, it is not necessary for the data transmitting apparatus to have a function of receiving a command for the spreading code to be used.
  • the spread codes used for spread spectrum modulation of a plurality of the data units in one frame format may be different and orthogonal to each other.
  • the data transmission device may be configured not to have a function of receiving a signal.
  • the data units adjacent to each other in one frame format are subjected to spread spectrum modulation using spreading codes orthogonal to each other, the probability of occurrence of signal collision that cannot be demodulated by the data receiving apparatus is reduced. Since there is no need to instruct a spreading code to be used from the data receiving apparatus to the data transmitting apparatus, it is not necessary for the data transmitting apparatus to have a signal receiving function. Even if the number of data transmission devices increases, the demodulation processing in the reception device can be performed by the same routine, and there is no need to increase the number of spreading codes to be used.
  • FIG. 1A is a schematic diagram of a wireless communication system according to an embodiment
  • FIG. 1B is a block diagram of a data transmission apparatus.
  • FIG. 2A is a diagram illustrating an example of a frame format of a modulated signal
  • FIG. 2B is a diagram illustrating a relationship between a received signal and a flag search interval in time series.
  • FIG. 3A is a diagram illustrating input / output data of the spread spectrum modulation unit
  • FIG. 3B is a data unit of transmission data, a spread code used for spread spectrum modulation, and a data unit of a spread spectrum modulated signal
  • FIG. FIG. 4 is a diagram for explaining demodulation processing (despreading processing) of a data unit subjected to spread spectrum modulation.
  • FIGS. 5A and 5B are timing charts of signal frames transmitted from a plurality of data transmission apparatuses of the communication system according to the embodiment.
  • FIGS. 5C and 5D are transmissions from a plurality of data transmission apparatuses of the communication system according to the comparative example.
  • FIG. 5A and 5B are timing charts of signal frames transmitted from a plurality of data transmission apparatuses of the communication system according to the embodiment.
  • FIGS. 5C and 5D are transmissions from a plurality of data transmission apparatuses of the communication system according to the comparative example.
  • FIG. 1A shows a schematic diagram of a wireless communication system according to an embodiment.
  • the wireless communication system according to the embodiment includes a plurality of data transmission devices 10 that transmit signals, and a data reception device 30 that receives signals transmitted from the data transmission devices 10.
  • the plurality of data transmission devices 10 transmit signals independently of each other in time.
  • FIG. 1B shows a block diagram of the data transmission device 10.
  • Transmission data 11 is input to the spread spectrum modulator 14.
  • the spread spectrum modulation unit 14 generates a modulated signal MS by performing spread spectrum modulation of the transmission data 11 using the spread code SC generated by the spread code generation unit 12.
  • the carrier wave generator 16 generates a carrier wave CW.
  • Modulation signal MS and carrier wave CW are input to on / off modulator 18.
  • the on / off modulator 18 performs on / off modulation (OOK) on the carrier wave CW based on the modulation signal MS. Note that other modulation schemes may be applied instead of the on / off modulation.
  • the modulated signal is radiated from the antenna 19.
  • FIG. 2A shows an example of the frame format of the modulation signal MS.
  • One frame is composed of a plurality of data units U1 to U6 having, for example, 1024 bits.
  • Each of the data units U1 to U6 is a unit for performing spread spectrum modulation.
  • FIG. 2A shows an example in which one frame is composed of six data units U1 to U6, the number of data units constituting one frame is not limited to six. Note that the number of data units included in one frame is the same among all data transmission apparatuses 10.
  • the data units U1 to U6 are each subjected to spread spectrum modulation using spreading codes SC1 to SC6 that are orthogonal to each other.
  • the spreading codes SC1 to SC6 for example, PN series spreading codes such as Gold series and M series are used. Different spreading codes are applied to two data units adjacent to each other on the time axis. For this reason, the spreading codes applied to two data units adjacent to each other on the time axis are orthogonal to each other.
  • the spreading codes SC1 to SC6 are preferably selected so that the spreading codes SC1 to SC6 applied to the plurality of data units U1 to U6 are orthogonal to each other.
  • the spreading codes applied to the data units at corresponding positions of the plurality of data transmission apparatuses 10 are the same among the plurality of data transmission apparatuses 10.
  • the preceding two data units U1 and U2 constitute a preamble field 20
  • the remaining four data units U3 to U6 constitute a data field 21.
  • the values of the data units U1 and U2 included in the preamble field 20 are equal to the spreading codes SC1 and SC2, respectively.
  • the data units U1 and U2 serve as flags for detecting the head position of the frame.
  • the spreading codes SC1 and SC2 are referred to as a first flag F1 and a second flag F2, respectively.
  • Information to be transmitted is stored in the data units U3 to U6.
  • the temperature sensor identification number and the temperature sensor identification number are sent to the data units U3 to U6.
  • the measurement result is stored.
  • a flag search process is performed on the bit string of the signal received by the data receiving device 30 (FIG. 1) for each field length of the data unit twice, that is, for each 2048 bit length.
  • a correlation operation is performed between the bit string of the 2048-bit received signal and the first flag F1 (spreading code SC1) and the second flag F2 (spreading code SC2).
  • a 2048-bit section to be subjected to correlation calculation in the received signal bit string is a flag search section 23.
  • a correlation peak is present at a position on the time axis where the first flag F1 or the second flag F2 is present. appear.
  • a peak exceeding the determination threshold appears, it is determined that the position where the peak appears (position on the time axis) in the flag search section 23 of the received signal includes the first flag F1 or the second flag F2.
  • FIG. 2B shows the relationship between the received signal and the flag search section 23 in time series.
  • a part of the data unit U1 is included in the flag search section 23 at time t1.
  • the flag search process is performed at the time t1, but no correlation peak exceeding the threshold value appears, and either the data unit U1 set to the first flag F1 or the data unit U2 set to the second flag F2 Is not detected. Further, flag search processing is performed at time t2 when the received signal is shifted by 1024 bits. At this time, the position of the data unit U1 on the time axis is specified by detecting the first flag F1 in the flag search section 23.
  • the position of the data unit U2 on the time axis is specified by detecting the second flag F2 in the flag search section 23. If the position where the data unit U1 is detected at the time t2 and the position where the data unit U2 is detected at the time t3 are the same, it is determined that the preamble field 20 (FIG. 2A) has been detected.
  • the preamble field 20 is composed of two data units U1 and U2, but the preamble field 20 may be composed of only one data unit U1. If the preamble field 20 is composed of two data units U1 and U2, flag detection accuracy can be increased.
  • a method of performing spread spectrum modulation on the transmission data 11 will be described with reference to FIGS. 3A and 3B.
  • the spread spectrum method is not limited to the following method.
  • FIG. 3A shows input / output data of the spread spectrum modulation section 14.
  • the transmission data 11 and the spread codes SC1 to SC6 generated by the spread code generator 12 are input to the spread spectrum modulator 14.
  • the transmission data 11 includes data units U1 to U6, and the data length of each data unit U1 to U6 is 10 bits. That is, each data unit U1 to U6 of the transmission data 11 takes a value from 0 to 1023.
  • the data length of each of the spreading codes SC1 to SC6 is 1024 bits.
  • the spread spectrum modulation section 14 performs spread spectrum modulation on the data units U1 to U6 of the transmission data 11 using the spread codes SC1 to SC6, respectively, and generates a spread spectrum modulated modulation signal MS.
  • Modulated signal MS includes data units U1 to U6 in which data units U1 to U6 of transmission data 11 are respectively subjected to spread spectrum modulation.
  • the data length of each of the data units U1 to U6 of the modulation signal MS is 1024 bits.
  • FIG. 3B shows one data unit U3 of the transmission data 11, a spread code SC3 used for spread spectrum modulation, and a data unit U3 of the modulation signal MS subjected to spread spectrum modulation.
  • the spread spectrum modulation unit 14 When the value of the data unit U3 of the transmission data 11 is “n”, the spread spectrum modulation unit 14 generates the data unit U3 of the modulation signal MS by cyclically shifting the spread code SC3 by n bits. That is, the values from the 0th bit to the (1023-n) th bit of the spreading code SC3 coincide with the values from the nth bit to the 1023th bit of the data unit U3 of the modulation signal MS, respectively.
  • the values from the (1023-n + 1) th bit to the 1023th bit respectively match the values from the 0th bit to the (n-1) th bit of the data unit U3 of the modulation signal MS.
  • the spread spectrum modulation method of the other data units U1, U2, U4 to U6 of the transmission data 11 is the same as the method shown in FIG. 3B. Since data units U1 and U2 are used as flags for frame detection, the bit patterns of data units U1 and U2 of modulated signal MS are equal to the bit patterns of spreading codes SC1 and SC2, respectively.
  • FIG. 4 illustrates an example in which the data unit U3 of the transmission data 11 (FIG. 3A) is “n”. Correlation between the data unit U3 of the received signal frame SF and the spreading code SC3 is performed.
  • An example of the correlation calculation result is shown in a graph 35, and another example is shown in a graph 36.
  • the horizontal axis of the graphs 35 and 36 represents the number of bits for cyclically shifting the spreading code SC3, and the vertical axis represents the correlation value.
  • a peak appears at the position of the number n of cyclic shifts in the spread spectrum modulation.
  • the determination threshold Th the data unit U3 is demodulated to the value “n”, and the demodulation process ends normally.
  • the other graph 36 when a peak exceeding the determination threshold Th does not appear, it is determined that demodulation is impossible.
  • FIG. 5A shows an example of a timing chart of signal frames SF1 and SF2 transmitted from a plurality of data transmission apparatuses 10 (FIG. 1) of the communication system according to the embodiment.
  • Each of the data units U1 to U6 of the signal frames SF1 and SF2 is subjected to spread spectrum modulation using spreading codes SC1 to SC6, respectively.
  • the spreading codes SC1 to SC6 are orthogonal to each other.
  • the data unit U1 of the signal frame SF1 and the data unit U1 of the signal frame SF2 partially overlap on the time axis. Since the data unit U1 of the preceding signal frame SF1 and the data unit U1 of the subsequent signal frame SF2 are spread spectrum modulated using the same spreading code SC1, the data unit U1 of the preceding signal frame SF1 and It is difficult to detect the data unit U1 of the subsequent signal frame SF2.
  • the second data unit U2 of the preceding signal frame SF1 and the first data unit U1 of the subsequent signal frame SF2 partially overlap on the time axis. Units U1 do not overlap.
  • the data unit U2 of the preceding signal frame SF1 and the data unit U1 of the subsequent signal frame SF2 are spread spectrum modulated using spreading codes SC2 and SC1 that are orthogonal to each other. For this reason, even if the data unit U2 of the preceding signal frame SF1 and the data unit U1 of the subsequent signal frame SF2 overlap, the data receiving device 30 (FIG. 1) can detect both separately. it can.
  • the third data unit U3 to the sixth data unit U6 of the preceding signal frame SF1 and the second data unit U2 to the sixth data unit U6 of the subsequent signal frame SF2 can be normally decoded. it can.
  • FIG. 5C shows an example of a timing chart of the signal frames SF3 and SF4 transmitted from the plurality of data transmission apparatuses 10 (FIG. 1) of the communication system according to the comparative example.
  • the data units U1 to U6 are spread spectrum modulated using the same spreading code SC1.
  • the temporal relationship between the preceding signal frame SF3 and the subsequent signal frame SF4 is the same as the relationship between the preceding signal frame SF1 and the subsequent signal frame SF2 shown in FIG. 5B. That is, the second data unit U2 of the preceding signal frame SF3 and the first data unit U1 of the subsequent signal frame SF4 partially overlap on the time axis.
  • the preceding signal frame SF3 and the first data unit U1 of the succeeding signal frame SF4 are spread spectrum modulated using the same spreading code SC1, the preceding signal frame SF3 It is difficult to detect the second data unit U2 and the first data unit U1 of the subsequent signal frame SF4.
  • the probability of signal collision that cannot be decoded can be reduced as compared with the communication system according to the comparative example.
  • the number of data transmission devices 10 that perform transmission operation at random timing is three, and the time length of one data unit is 0.05 seconds.
  • the probability that a signal collision that cannot be decoded occurs is about 1%.
  • the probability that a signal collision that cannot be decoded occurs under the same condition is about 6%.
  • the spreading codes SC1 to SC6 used for the data units U1 to U6 are fixed. Therefore, it is not necessary for the data receiving device 30 (FIG. 1) to instruct the data transmitting device 10 (FIG. 1) about the spreading code to be used. For this reason, it is not necessary for the data transmitting apparatus 10 to have a signal receiving function. As a result, it is possible to avoid an increase in cost and an increase in power consumption due to the reception function.
  • the resistance to signal collision is high.
  • the number of data transmission apparatuses 10 increases, the number of spreading codes to be used must also be increased.
  • the data receiving device 30 has to increase the number of decoding processing routines corresponding to the increase in the spreading codes to be used.
  • the number of spreading codes to be used is determined by the number of data units U1 to U6 constituting the frame. Even if the number of data transmission devices 10 increases, it is not necessary to increase the number of spreading codes to be used. For this reason, even if the number of data transmitting apparatuses 10 increases, it is not necessary to increase the number of decoding processing routines to be prepared in the data receiving apparatus 30.

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Abstract

In the present invention, a data receiving device receives signals sent from a plurality of data transmission devices. The signals sent from each of the data transmission devices have a frame format comprising a plurality of data units that become the units for doing spread spectrum modulation using a spreading code. Data units that are mutually adjacent within a single frame format are modulated using mutually orthogonal spreading codes. The number of data units included in a single frame format is the same for the plurality of data transmission devices, and data units in corresponding positions undergo spread spectrum modulation using the same spreading code. Without providing a signal receiving function to a data transmission device in a spread spectrum communication system, it is possible to suppress an increase in the number of demodulation routines in a receiving device, and suppress an increase in the probability of signal collisions that cannot be demodulated.

Description

無線通信システム、及び無線通信システムに用いられるデータ送信装置RADIO COMMUNICATION SYSTEM AND DATA TRANSMISSION DEVICE USED FOR RADIO COMMUNICATION SYSTEM
　本発明は、スペクトラム拡散変調された信号を送信するデータ送信装置と、データ送信装置から送信された信号を受信するデータ受信装置とを有する無線通信システムに関する。 The present invention relates to a wireless communication system having a data transmission device that transmits a signal subjected to spread spectrum modulation and a data reception device that receives a signal transmitted from the data transmission device.
　基地局装置と、複数の移動局装置とが、ＤＳ－ＣＤＭＡ方式で接続される移動通信システムが下記の特許文献１に開示されている。この移動通信システムでは、各移動局装置から基地局装置に送信される信号が、複数の情報ユニットで構成される。第１の情報ユニットは、システム共通の拡散コードでスペクトラム拡散変調される。第１の情報ユニットに続く第２の情報ユニット以降の情報ユニットは、移動局装置毎に異なる拡散コードでスペクトラム拡散変調される。 A mobile communication system in which a base station apparatus and a plurality of mobile station apparatuses are connected by the DS-CDMA system is disclosed in Patent Document 1 below. In this mobile communication system, a signal transmitted from each mobile station apparatus to a base station apparatus is composed of a plurality of information units. The first information unit is spread spectrum modulated with a system-wide spreading code. The information units subsequent to the second information unit following the first information unit are subjected to spread spectrum modulation with a different spreading code for each mobile station apparatus.
　第２の情報ユニット以降の情報ユニットのスペクトラム拡散に用いられる拡散コードは、予め移動局装置ごとに割り当てておいてもよいし、第１の情報ユニットを送信した後、基地局装置から指令されるようにしてもよい。 The spreading code used for the spread spectrum of the information units subsequent to the second information unit may be assigned to each mobile station device in advance, or commanded from the base station device after transmitting the first information unit. You may do it.
　複数の移動局装置間で競合が生じるのは、共通の拡散コードが用いられる第１の情報ユニットの送信時間が重なった場合のみである。第１の情報ユニットの送信時間は、全ての情報ユニットの送信時間に比べて十分短い。このため、アクセスの競合が生じる確率が小さくなる。 A competition occurs between a plurality of mobile station apparatuses only when the transmission times of the first information units using a common spreading code overlap. The transmission time of the first information unit is sufficiently shorter than the transmission times of all information units. This reduces the probability of access contention.
特開平１０－１２６３７９号公報Japanese Patent Laid-Open No. 10-126379
　複数のデータ送信装置から１つのデータ受信装置への上り方向にデータが転送されるが、逆の下り方向にはデータが転送されない通信システムが構築される場合がある。このような通信システムは、例えば、多数の測定点に設置された温度センサ等のセンサで取得された測定結果を、管理センタに送信するような用途に適用される。この通信システムにおいては、各測定点にデータ送信装置が設置され、管理センタにデータ受信装置が設置される。 In some cases, a communication system is constructed in which data is transferred in the uplink direction from a plurality of data transmission apparatuses to one data reception apparatus, but data is not transferred in the reverse downlink direction. Such a communication system is applied, for example, to an application in which measurement results acquired by sensors such as temperature sensors installed at a large number of measurement points are transmitted to a management center. In this communication system, a data transmission device is installed at each measurement point, and a data reception device is installed at the management center.
　また、一般に通信を行う場合、雑音に強い通信方式を適用することが望まれる。雑音に強い通信方式として、スペクトラム拡散通信方式が挙げられる。スペクトラム拡散通信方式では、データ送信装置が、拡散コードを用いて、送信データをスペクトラム拡散変調し、データ受信装置が、同一の拡散コードを用いて、受信した信号を復調する。データ受信装置では、受信した信号に用いられている拡散コードに応じて、復調処理のルーチンが切り替えられる。 In general, it is desirable to apply a communication system that is resistant to noise when performing communication. A spread spectrum communication system is an example of a communication system that is resistant to noise. In the spread spectrum communication system, a data transmission device performs spread spectrum modulation on transmission data using a spread code, and a data reception device demodulates a received signal using the same spread code. In the data receiving apparatus, the demodulation processing routine is switched in accordance with the spreading code used for the received signal.
　データ送信装置ごとに固有の拡散コードを割り当てる方式では、データ送信装置の数が増加するに従って、使用する拡散コードの数も増加する。拡散コードの数が増加すると、データ受信装置で、拡散コードに応じた復調処理のルーチンの切り替えの負担が大きくなる。 In the method of assigning a unique spreading code to each data transmission device, the number of spreading codes to be used increases as the number of data transmission devices increases. As the number of spreading codes increases, the burden of switching the demodulation processing routine according to the spreading code increases in the data receiving apparatus.
　データ送信装置で使用する拡散コードを、一連の通信毎に、データ受信装置からデータ送信装置に指示する方式では、データ送信装置に、信号の受信機能を持たせなければならない。データ送信装置に受信機能を持たせることは、データ送信装置の消費電力増大及びコスト増につながる。 In the method of instructing the spreading code used in the data transmission apparatus from the data reception apparatus to the data transmission apparatus for each series of communications, the data transmission apparatus must have a signal reception function. Giving the data transmission device a reception function leads to an increase in power consumption and cost of the data transmission device.
　本発明の目的は、スペクトラム拡散通信方式のデータ送信装置に、信号の受信機能を持たせることなく、受信装置における復調処理のルーチンの個数の増加を抑制し、かつ復調不能な信号衝突の発生確率の増大を抑制することが可能な無線通信システムを提供することである。 An object of the present invention is to suppress the increase in the number of demodulation processing routines in the receiving apparatus without giving the signal receiving function to the data transmission apparatus of the spread spectrum communication method, and the probability of occurrence of a signal collision that cannot be demodulated. It is an object of the present invention to provide a radio communication system capable of suppressing an increase in the frequency.
　本発明の一観点によると、
　信号を送信する複数のデータ送信装置と、
　複数の前記データ送信装置から送信された前記信号を受信するデータ受信装置と
を有し、
　前記データ送信装置の各々から送信される前記信号は、拡散コードを用いてスペクトラム拡散変調を行う単位となる複数のデータユニットが時間軸上に並ぶフレームフォーマットを有し、１つの前記フレームフォーマット内で相互に隣り合う前記データユニットは、相互に直交する拡散コードを用いてスペクトラム拡散変調されており、
　１つの前記フレームフォーマットに含まれる前記データユニットの個数は、複数の前記データ送信装置において同一であり、
　複数の前記データ送信装置から送信される前記信号の前記フレームフォーマットの、対応する位置の前記データユニットが、同一の前記拡散コードを用いてスペクトラム拡散変調されている通信システムが提供される。 According to one aspect of the invention,
A plurality of data transmission devices for transmitting signals;
A data receiving device that receives the signals transmitted from a plurality of the data transmitting devices,
The signal transmitted from each of the data transmission devices has a frame format in which a plurality of data units, which are units for performing spread spectrum modulation using a spreading code, are arranged on the time axis, and within one frame format The data units adjacent to each other are spread spectrum modulated using spreading codes orthogonal to each other,
The number of the data units included in one frame format is the same in a plurality of the data transmission devices,
There is provided a communication system in which the data units at corresponding positions in the frame format of the signals transmitted from a plurality of the data transmission devices are subjected to spread spectrum modulation using the same spreading code.
　１つの前記フレームフォーマット内で相互に隣り合うデータユニットが、相互に直交する拡散コードを用いてスペクトラム拡散変調されているため、データ受信装置で復調不能な信号衝突の発生確率が低減される。データ受信装置からデータ送信装置に、使用すべき拡散コードを指令する必要がないため、データ送信装置に信号の受信機能を持たせる必要がない。また、データ送信装置の台数が増えても、使用する拡散コードの数を増やす必要がない。 Since the data units adjacent to each other in one frame format are subjected to spread spectrum modulation using spreading codes orthogonal to each other, the probability of occurrence of signal collision that cannot be demodulated by the data receiving apparatus is reduced. Since there is no need to instruct a spreading code to be used from the data receiving apparatus to the data transmitting apparatus, it is not necessary for the data transmitting apparatus to have a signal receiving function. Further, even if the number of data transmission devices increases, it is not necessary to increase the number of spreading codes to be used.
　１つの前記フレームフォーマット内の複数の前記データユニットのスペクトラム拡散変調に用いられる前記拡散コードは、すべて異なり、相互に直交する構成としてもよい。これにより、データ受信装置で復調不能な信号衝突の発生確率が、より低減される。 The spread codes used for spread spectrum modulation of a plurality of the data units in one frame format may be different and orthogonal to each other. As a result, the probability of signal collision that cannot be demodulated by the data receiving apparatus is further reduced.
　前記データ送信装置は、前記信号を送信する機能を有するが、前記データ受信装置からの信号を受信する機能を持たない構成としてもよい。これにより、データ送信装置の消費電力の増大、及びコストの増加を回避することができる。 The data transmitting device may have a function of transmitting the signal, but may not have a function of receiving a signal from the data receiving device. Thereby, it is possible to avoid an increase in power consumption and an increase in cost of the data transmission apparatus.
　複数の前記データ送信装置は、相互に独立して前記信号を送信する構成としてもよい。 A plurality of the data transmission devices may be configured to transmit the signals independently of each other.
　本発明の他の観点によると、
　搬送波を発生する搬送波発生部と、
　変調信号を発生するスペクトラム拡散変調部と、
　前記変調信号に基づいて、前記搬送波を変調する変調部と、
　前記変調部で変調された信号を、データ受信装置に送信するアンテナと
を有し、
　前記変調信号は、拡散コードを用いてスペクトラム拡散変調を行う単位となる複数のデータユニットが時間軸上に並ぶフレームフォーマットを有し、１つの前記フレームフォーマット内で相互に隣り合う前記データユニットは、相互に直交する拡散コードを用いてスペクトラム拡散変調されているデータ送信装置が提供される。 According to another aspect of the invention,
A carrier generation unit for generating a carrier;
A spread spectrum modulation section for generating a modulation signal;
A modulation unit that modulates the carrier wave based on the modulation signal;
An antenna for transmitting the signal modulated by the modulation unit to a data receiving device;
The modulation signal has a frame format in which a plurality of data units serving as units for performing spread spectrum modulation using a spreading code are arranged on a time axis, and the data units adjacent to each other in one frame format are: There is provided a data transmission apparatus that is spread spectrum modulated using spreading codes that are orthogonal to each other.
　１つの前記フレームフォーマット内で相互に隣り合うデータユニットが、相互に直交する拡散コードを用いてスペクトラム拡散変調されているため、複数のデータ送信装置からランダムに信号を送信しても、復調不能な信号衝突の発生確率が低減される。拡散コードを、予めデータ送信装置に固定的に設定しておくことができるため、データ送信装置に、使用する拡散コードの指令を受信する機能を持たせる必要がない。 Since data units adjacent to each other in one frame format are spread spectrum modulated using spreading codes orthogonal to each other, even if signals are randomly transmitted from a plurality of data transmission apparatuses, they cannot be demodulated. The probability of signal collision occurrence is reduced. Since the spreading code can be fixedly set in the data transmitting apparatus in advance, it is not necessary for the data transmitting apparatus to have a function of receiving a command for the spreading code to be used.
　１つの前記フレームフォーマット内の複数の前記データユニットのスペクトラム拡散変調に用いられる前記拡散コードは、すべて異なり、相互に直交する構成としてもよい。このデータ送信装置は、信号を受信する機能を持たない構成としてもよい。 The spread codes used for spread spectrum modulation of a plurality of the data units in one frame format may be different and orthogonal to each other. The data transmission device may be configured not to have a function of receiving a signal.
　１つの前記フレームフォーマット内で相互に隣り合うデータユニットが、相互に直交する拡散コードを用いてスペクトラム拡散変調されているため、データ受信装置で復調不能な信号衝突の発生確率が低減される。データ受信装置からデータ送信装置に、使用すべき拡散コードを指令する必要がないため、データ送信装置に信号の受信機能を持たせる必要がない。また、データ送信装置の台数が増えても、受信装置における復調処理は同一のルーチンで行うことができ、使用する拡散コードの数を増やす必要がない。 Since the data units adjacent to each other in one frame format are subjected to spread spectrum modulation using spreading codes orthogonal to each other, the probability of occurrence of signal collision that cannot be demodulated by the data receiving apparatus is reduced. Since there is no need to instruct a spreading code to be used from the data receiving apparatus to the data transmitting apparatus, it is not necessary for the data transmitting apparatus to have a signal receiving function. Even if the number of data transmission devices increases, the demodulation processing in the reception device can be performed by the same routine, and there is no need to increase the number of spreading codes to be used.
図１Ａは、実施例による無線通信システムの概略図であり、図１Ｂは、データ送信装置のブロック図である。FIG. 1A is a schematic diagram of a wireless communication system according to an embodiment, and FIG. 1B is a block diagram of a data transmission apparatus. 図２Ａは、変調信号のフレームフォーマットの一例を示す図であり、図２Ｂは、受信信号とフラグ探索区間との関係を時系列で示す図である。FIG. 2A is a diagram illustrating an example of a frame format of a modulated signal, and FIG. 2B is a diagram illustrating a relationship between a received signal and a flag search interval in time series. 図３Ａは、スペクトラム拡散変調部の入出力データを示す図であり、図３Ｂは、送信データの１つのデータユニット、スペクトラム拡散変調に用いられる拡散コード、及びスペクトラム拡散変調された変調信号のデータユニットを示す図である。FIG. 3A is a diagram illustrating input / output data of the spread spectrum modulation unit, and FIG. 3B is a data unit of transmission data, a spread code used for spread spectrum modulation, and a data unit of a spread spectrum modulated signal FIG. 図４は、スペクトラム拡散変調されたデータユニットの復調処理（逆拡散処理）を説明する図である。FIG. 4 is a diagram for explaining demodulation processing (despreading processing) of a data unit subjected to spread spectrum modulation. 図５Ａ及び図５Ｂは、実施例による通信システムの複数のデータ送信装置から送信される信号フレームのタイミングチャートであり、図５Ｃ及び図５Ｄは、比較例による通信システムの複数のデータ送信装置から送信される信号フレームのタイミングチャートである。5A and 5B are timing charts of signal frames transmitted from a plurality of data transmission apparatuses of the communication system according to the embodiment. FIGS. 5C and 5D are transmissions from a plurality of data transmission apparatuses of the communication system according to the comparative example. FIG.
　図１Ａに、実施例による無線通信システムの概略図を示す。実施例による無線通信システムは、信号を送信する複数のデータ送信装置１０、及びデータ送信装置１０から送信された信号を受信するデータ受信装置３０を含む。複数のデータ送信装置１０は、時間的に相互に独立して信号を送信する。 FIG. 1A shows a schematic diagram of a wireless communication system according to an embodiment. The wireless communication system according to the embodiment includes a plurality of data transmission devices 10 that transmit signals, and a data reception device 30 that receives signals transmitted from the data transmission devices 10. The plurality of data transmission devices 10 transmit signals independently of each other in time.
　図１Ｂに、データ送信装置１０のブロック図を示す。送信データ１１がスペクトラム拡散変調部１４に入力される。スペクトラム拡散変調部１４は、拡散コード発生部１２で発生した拡散コードＳＣを用いて、送信データ１１のスペクトラム拡散変調を行うことにより、変調信号ＭＳを生成する。搬送波発生部１６が搬送波ＣＷを発生する。変調信号ＭＳ及び搬送波ＣＷが、オンオフ変調部１８に入力される。オンオフ変調部１８は、変調信号ＭＳに基づいて搬送波ＣＷに対してオンオフ変調（ＯＯＫ）を行う。なお、オンオフ変調に代えて、他の変調方式を適用してもよい。変調された信号が、アンテナ１９から放射される。 FIG. 1B shows a block diagram of the data transmission device 10. Transmission data 11 is input to the spread spectrum modulator 14. The spread spectrum modulation unit 14 generates a modulated signal MS by performing spread spectrum modulation of the transmission data 11 using the spread code SC generated by the spread code generation unit 12. The carrier wave generator 16 generates a carrier wave CW. Modulation signal MS and carrier wave CW are input to on / off modulator 18. The on / off modulator 18 performs on / off modulation (OOK) on the carrier wave CW based on the modulation signal MS. Note that other modulation schemes may be applied instead of the on / off modulation. The modulated signal is radiated from the antenna 19.
　図２Ａに、変調信号ＭＳのフレームフォーマットの一例を示す。１つのフレームは、例えば１０２４ビットの複数のデータユニットＵ１～Ｕ６で構成される。データユニットＵ１～Ｕ６の各々が、スペクトラム拡散変調を行う単位となる。図２Ａでは、１つのフレームが６個のデータユニットＵ１～Ｕ６で構成されている例を示したが、１つのフレームを構成するデータユニットの個数は、６個に限らない。なお、１つのフレームに含まれるデータユニットの個数は、すべてのデータ送信装置１０の間で同一である。 FIG. 2A shows an example of the frame format of the modulation signal MS. One frame is composed of a plurality of data units U1 to U6 having, for example, 1024 bits. Each of the data units U1 to U6 is a unit for performing spread spectrum modulation. Although FIG. 2A shows an example in which one frame is composed of six data units U1 to U6, the number of data units constituting one frame is not limited to six. Note that the number of data units included in one frame is the same among all data transmission apparatuses 10.
　データユニットＵ１～Ｕ６は、それぞれ、相互に直交する拡散コードＳＣ１～ＳＣ６を用いてスペクトラム拡散変調されている。拡散コードＳＣ１～ＳＣ６として、例えばゴールド系列、Ｍ系列等のＰＮ系列の拡散コードが用いられる。時間軸上で相互に隣り合う２つのデータユニットには、相互に異なる拡散コードが適用される。このため、時間軸上で相互に隣り合う２つのデータユニットに適用される拡散コードは、相互に直交する。なお、複数のデータユニットＵ１～Ｕ６にそれぞれ適用される拡散コードＳＣ１～ＳＣ６が、相互に直交するように、拡散コードＳＣ１～ＳＣ６を選択することが好ましい。複数のデータ送信装置１０（図１Ａ）の、対応する位置のデータユニットに適用される拡散コードは、複数のデータ送信装置１０の間で同一である。 The data units U1 to U6 are each subjected to spread spectrum modulation using spreading codes SC1 to SC6 that are orthogonal to each other. As the spreading codes SC1 to SC6, for example, PN series spreading codes such as Gold series and M series are used. Different spreading codes are applied to two data units adjacent to each other on the time axis. For this reason, the spreading codes applied to two data units adjacent to each other on the time axis are orthogonal to each other. The spreading codes SC1 to SC6 are preferably selected so that the spreading codes SC1 to SC6 applied to the plurality of data units U1 to U6 are orthogonal to each other. The spreading codes applied to the data units at corresponding positions of the plurality of data transmission apparatuses 10 (FIG. 1A) are the same among the plurality of data transmission apparatuses 10.
　一例として、６個のデータユニットＵ１～Ｕ６のうち、先行する２つのデータユニットＵ１、Ｕ２によってプリアンブルフィールド２０が構成され、残りの４つのデータユニットＵ３～Ｕ６によってデータフィールド２１が構成される。プリアンブルフィールド２０に含まれるデータユニットＵ１、Ｕ２の値は、それぞれ拡散コードＳＣ１、ＳＣ２に等しい。データユニットＵ１、Ｕ２は、フレームの先頭位置を検出するためのフラグとしての役割を有する。拡散コードＳＣ１、ＳＣ２を、それぞれ第１のフラグＦ１、第２のフラグＦ２ということとする。 As an example, among six data units U1 to U6, the preceding two data units U1 and U2 constitute a preamble field 20, and the remaining four data units U3 to U6 constitute a data field 21. The values of the data units U1 and U2 included in the preamble field 20 are equal to the spreading codes SC1 and SC2, respectively. The data units U1 and U2 serve as flags for detecting the head position of the frame. The spreading codes SC1 and SC2 are referred to as a first flag F1 and a second flag F2, respectively.
　データユニットＵ３～Ｕ６に、送信すべき情報が格納されている。複数の測定点に配置された温度センサで測定された温度情報を、データ受信装置３０（図１Ａ）に送信する場合には、データユニットＵ３～Ｕ６に、温度センサの識別番号、及び温度センサの測定結果が格納される。 Information to be transmitted is stored in the data units U3 to U6. When the temperature information measured by the temperature sensors arranged at a plurality of measurement points is transmitted to the data receiving device 30 (FIG. 1A), the temperature sensor identification number and the temperature sensor identification number are sent to the data units U3 to U6. The measurement result is stored.
　図２Ｂを参照して、プリアンブルフィールド２０（図２Ａ）の探索手順について説明する。データ受信装置３０（図１）で受信された信号のビット列に対して、データユニットの各々のフィールド長の２倍、すなわち２０４８ビット長ごとに、フラグ探索処理を行う。１回のフラグ探索処理において、２０４８ビットの受信信号のビット列と、第１のフラグＦ１（拡散コードＳＣ１）及び第２のフラグＦ２（拡散コードＳＣ２）との相関演算を行う。 The search procedure for the preamble field 20 (FIG. 2A) will be described with reference to FIG. 2B. A flag search process is performed on the bit string of the signal received by the data receiving device 30 (FIG. 1) for each field length of the data unit twice, that is, for each 2048 bit length. In one flag search process, a correlation operation is performed between the bit string of the 2048-bit received signal and the first flag F1 (spreading code SC1) and the second flag F2 (spreading code SC2).
　受信信号のビット列のうち、相関演算を行う対象となる２０４８ビットの区間をフラグ探索区間２３ということとする。フラグ探索区間２３内に、第１のフラグＦ１または第２のフラグＦ２が存在する場合には、第１のフラグＦ１または第２のフラグＦ２が存在する時間軸上の位置に、相関のピークが現れる。判定閾値を超えるピークが現れると、受信信号のフラグ探索区間２３内の、ピークが現れた位置（時間軸上の位置）に、第１のフラグＦ１または第２のフラグＦ２が含まれると判定される。 Suppose that a 2048-bit section to be subjected to correlation calculation in the received signal bit string is a flag search section 23. When the first flag F1 or the second flag F2 is present in the flag search section 23, a correlation peak is present at a position on the time axis where the first flag F1 or the second flag F2 is present. appear. When a peak exceeding the determination threshold appears, it is determined that the position where the peak appears (position on the time axis) in the flag search section 23 of the received signal includes the first flag F1 or the second flag F2. The
　図２Ｂは、受信信号とフラグ探索区間２３との関係を時系列で示す。時刻ｔ１において、データユニットＵ１の一部が、フラグ探索区間２３に含まれている。時刻ｔ１の時点でフラグ探索処理が行われるが、閾値を超える相関のピークは現れず、第１のフラグＦ１に設定されたデータユニットＵ１及び第２のフラグＦ２に設定されたデータユニットＵ２のいずれも検出されない。さらに、受信信号が１０２４ビットシフトした時刻ｔ２の時点でフラグ探索処理が行われる。この時点で、フラグ探索区間２３内に第１のフラグＦ１が検出されることにより、データユニットＵ１の時間軸上の位置が特定される。 FIG. 2B shows the relationship between the received signal and the flag search section 23 in time series. A part of the data unit U1 is included in the flag search section 23 at time t1. The flag search process is performed at the time t1, but no correlation peak exceeding the threshold value appears, and either the data unit U1 set to the first flag F1 or the data unit U2 set to the second flag F2 Is not detected. Further, flag search processing is performed at time t2 when the received signal is shifted by 1024 bits. At this time, the position of the data unit U1 on the time axis is specified by detecting the first flag F1 in the flag search section 23.
　さらに、受信信号が１０２４ビットシフトした時刻ｔ３において、フラグ探索区間２３内に第２のフラグＦ２が検出されることにより、データユニットＵ２の時間軸上の位置が特定される。時刻ｔ２でデータユニットＵ１が検出された位置と、時刻ｔ３でデータユニットＵ２が検出された位置とが同一である場合、プリアンブルフィールド２０（図２Ａ）が検出されたと判断される。 Furthermore, at time t3 when the received signal is shifted by 1024 bits, the position of the data unit U2 on the time axis is specified by detecting the second flag F2 in the flag search section 23. If the position where the data unit U1 is detected at the time t2 and the position where the data unit U2 is detected at the time t3 are the same, it is determined that the preamble field 20 (FIG. 2A) has been detected.
　図２Ａでは、プリアンブルフィールド２０を２つのデータユニットＵ１、Ｕ２で構成したが、１つのデータユニットＵ１のみでプリアンブルフィールド２０を構成してもよい。２つのデータユニットＵ１、Ｕ２でプリアンブルフィールド２０を構成すると、フラグの検出精度を高めることができる。 In FIG. 2A, the preamble field 20 is composed of two data units U1 and U2, but the preamble field 20 may be composed of only one data unit U1. If the preamble field 20 is composed of two data units U1 and U2, flag detection accuracy can be increased.
　図３Ａ及び図３Ｂを参照して、送信データ１１をスペクトラム拡散変調する方法について説明する。ただし、スペクトラム拡散の方法は、以下に示す方法に限定されない。 A method of performing spread spectrum modulation on the transmission data 11 will be described with reference to FIGS. 3A and 3B. However, the spread spectrum method is not limited to the following method.
　図３Ａは、スペクトラム拡散変調部１４の入出力データを示す。スペクトラム拡散変調部１４に、送信データ１１、及び拡散コード発生部１２で発生された拡散コードＳＣ１～ＳＣ６が入力される。送信データ１１は、データユニットＵ１～Ｕ６を含み、各データユニットＵ１～Ｕ６のデータ長は１０ビットである。すなわち、送信データ１１の各データユニットＵ１～Ｕ６は、０から１０２３までの値をとる。拡散コードＳＣ１～ＳＣ６の各々のデータ長は１０２４ビットである。 FIG. 3A shows input / output data of the spread spectrum modulation section 14. The transmission data 11 and the spread codes SC1 to SC6 generated by the spread code generator 12 are input to the spread spectrum modulator 14. The transmission data 11 includes data units U1 to U6, and the data length of each data unit U1 to U6 is 10 bits. That is, each data unit U1 to U6 of the transmission data 11 takes a value from 0 to 1023. The data length of each of the spreading codes SC1 to SC6 is 1024 bits.
　スペクトラム拡散変調部１４は、送信データ１１のデータユニットＵ１～Ｕ６に対して、それぞれ拡散コードＳＣ１～ＳＣ６を用いてスペクトル拡散変調を行い、スペクトラム拡散変調された変調信号ＭＳを生成する。変調信号ＭＳは、送信データ１１のデータユニットＵ１～Ｕ６がそれぞれスペクトラム拡散変調されたデータユニットＵ１～Ｕ６を含む。変調信号ＭＳのデータユニットＵ１～Ｕ６の各々のデータ長は、１０２４ビットである。 The spread spectrum modulation section 14 performs spread spectrum modulation on the data units U1 to U6 of the transmission data 11 using the spread codes SC1 to SC6, respectively, and generates a spread spectrum modulated modulation signal MS. Modulated signal MS includes data units U1 to U6 in which data units U1 to U6 of transmission data 11 are respectively subjected to spread spectrum modulation. The data length of each of the data units U1 to U6 of the modulation signal MS is 1024 bits.
　図３Ｂに、送信データ１１の１つのデータユニットＵ３、スペクトラム拡散変調に用いられる拡散コードＳＣ３、及びスペクトラム拡散変調された変調信号ＭＳのデータユニットＵ３を示す。送信データ１１のデータユニットＵ３の値が「ｎ」のとき、スペクトラム拡散変調部１４は、拡散コードＳＣ３をｎビットだけ巡回シフトさせることにより、変調信号ＭＳのデータユニットＵ３を生成する。すなわち、拡散コードＳＣ３の０ビット目から（１０２３－ｎ）ビット目までの値が、それぞれ変調信号ＭＳのデータユニットＵ３のｎビット目から１０２３ビット目までの値に一致し、拡散コードＳＣ３の（１０２３－ｎ＋１）ビット目から１０２３ビット目までの値が、それぞれ変調信号ＭＳのデータユニットＵ３の０ビット目から（ｎ－１）ビット目までの値に一致する。 FIG. 3B shows one data unit U3 of the transmission data 11, a spread code SC3 used for spread spectrum modulation, and a data unit U3 of the modulation signal MS subjected to spread spectrum modulation. When the value of the data unit U3 of the transmission data 11 is “n”, the spread spectrum modulation unit 14 generates the data unit U3 of the modulation signal MS by cyclically shifting the spread code SC3 by n bits. That is, the values from the 0th bit to the (1023-n) th bit of the spreading code SC3 coincide with the values from the nth bit to the 1023th bit of the data unit U3 of the modulation signal MS, respectively. The values from the (1023-n + 1) th bit to the 1023th bit respectively match the values from the 0th bit to the (n-1) th bit of the data unit U3 of the modulation signal MS.
　送信データ１１の他のデータユニットＵ１、Ｕ２、Ｕ４～Ｕ６のスペクトラム拡散変調方法も、図３Ｂに示した方法と同一である。なお、データユニットＵ１、Ｕ２は、フレーム検出用のフラグとして用いられるため、変調信号ＭＳのデータユニットＵ１、Ｕ２のビットパターンは、それぞれ拡散コードＳＣ１、ＳＣ２のビットパターンに等しい。 The spread spectrum modulation method of the other data units U1, U2, U4 to U6 of the transmission data 11 is the same as the method shown in FIG. 3B. Since data units U1 and U2 are used as flags for frame detection, the bit patterns of data units U1 and U2 of modulated signal MS are equal to the bit patterns of spreading codes SC1 and SC2, respectively.
　図４を参照して、スペクトラム拡散変調されたデータユニットＵ３の復調処理（逆拡散処理）について説明する。この復調処理は、データ受信装置３０（図１）で実行される。図４では、送信データ１１（図３Ａ）のデータユニットＵ３が「ｎ」である例について説明する。受信された信号フレームＳＦのデータユニットＵ３と拡散コードＳＣ３との相関演算を行う。 Referring to FIG. 4, the demodulation process (despreading process) of the spread spectrum modulated data unit U3 will be described. This demodulation process is executed by the data receiving device 30 (FIG. 1). FIG. 4 illustrates an example in which the data unit U3 of the transmission data 11 (FIG. 3A) is “n”. Correlation between the data unit U3 of the received signal frame SF and the spreading code SC3 is performed.
　相関演算結果の一例をグラフ３５に示し、他の例をグラフ３６に示す。グラフ３５、３６の横軸は、拡散コードＳＣ３を巡回シフトさせるビット数を表し、縦軸は相関値を表す。一方のグラフ３５において、スペクトラム拡散変調時における循環シフトのビット数ｎの位置にピークが現れている。このピークの高さ、すなわち相関値が判定閾値Ｔｈを超えている場合、データユニットＵ３は値「ｎ」に復調され、復調処理が正常に終了する。他方のグラフ３６に示すように、判定閾値Ｔｈを超えるピークが出現しない場合、復調不能と判定される。 An example of the correlation calculation result is shown in a graph 35, and another example is shown in a graph 36. The horizontal axis of the graphs 35 and 36 represents the number of bits for cyclically shifting the spreading code SC3, and the vertical axis represents the correlation value. In one graph 35, a peak appears at the position of the number n of cyclic shifts in the spread spectrum modulation. When the height of this peak, that is, the correlation value exceeds the determination threshold Th, the data unit U3 is demodulated to the value “n”, and the demodulation process ends normally. As shown in the other graph 36, when a peak exceeding the determination threshold Th does not appear, it is determined that demodulation is impossible.
　図５Ａに、実施例による通信システムの複数のデータ送信装置１０（図１）から送信される信号フレームＳＦ１、ＳＦ２のタイミングチャートの一例を示す。信号フレームＳＦ１、ＳＦ２の各々のデータユニットＵ１～Ｕ６は、それぞれ拡散コードＳＣ１～ＳＣ６を用いてスペクトラム拡散変調されている。拡散コードＳＣ１～ＳＣ６は、相互に直交する。 FIG. 5A shows an example of a timing chart of signal frames SF1 and SF2 transmitted from a plurality of data transmission apparatuses 10 (FIG. 1) of the communication system according to the embodiment. Each of the data units U1 to U6 of the signal frames SF1 and SF2 is subjected to spread spectrum modulation using spreading codes SC1 to SC6, respectively. The spreading codes SC1 to SC6 are orthogonal to each other.
　信号フレームＳＦ１のデータユニットＵ１と信号フレームＳＦ２のデータユニットＵ１とが、時間軸上で部分的に重なっている。先行する信号フレームＳＦ１のデータユニットＵ１と、後続の信号フレームＳＦ２のデータユニットＵ１とが、同一の拡散コードＳＣ１を用いてスペクトラム拡散変調されているため、先行する信号フレームＳＦ１のデータユニットＵ１、及び後続の信号フレームＳＦ２のデータユニットＵ１を検出することは困難である。 The data unit U1 of the signal frame SF1 and the data unit U1 of the signal frame SF2 partially overlap on the time axis. Since the data unit U1 of the preceding signal frame SF1 and the data unit U1 of the subsequent signal frame SF2 are spread spectrum modulated using the same spreading code SC1, the data unit U1 of the preceding signal frame SF1 and It is difficult to detect the data unit U1 of the subsequent signal frame SF2.
　図５Ｂに示した例では、先行する信号フレームＳＦ１の２番目のデータユニットＵ２と、後続の信号フレームＳＦ２の１番目のデータユニットＵ１とが、時間軸上で部分的に重なっているが、データユニットＵ１同士は重なっていない。先行する信号フレームＳＦ１のデータユニットＵ２と、後続の信号フレームＳＦ２のデータユニットＵ１とは、それぞれ相互に直交する拡散コードＳＣ２及びＳＣ１を用いてスペクトラム拡散変調されている。このため、先行する信号フレームＳＦ１のデータユニットＵ２と、後続の信号フレームＳＦ２のデータユニットＵ１とが重ねっていても、データ受信装置３０（図１）で、両者を分離して検出することができる。 In the example shown in FIG. 5B, the second data unit U2 of the preceding signal frame SF1 and the first data unit U1 of the subsequent signal frame SF2 partially overlap on the time axis. Units U1 do not overlap. The data unit U2 of the preceding signal frame SF1 and the data unit U1 of the subsequent signal frame SF2 are spread spectrum modulated using spreading codes SC2 and SC1 that are orthogonal to each other. For this reason, even if the data unit U2 of the preceding signal frame SF1 and the data unit U1 of the subsequent signal frame SF2 overlap, the data receiving device 30 (FIG. 1) can detect both separately. it can.
　また、先行する信号フレームＳＦ１の３番目のデータユニットＵ３～６番目のデータユニットＵ６、及び後続の信号フレームＳＦ２の２番目のデータユニットＵ２～６番目のデータユニットＵ６も、正常に復号することができる。 Also, the third data unit U3 to the sixth data unit U6 of the preceding signal frame SF1 and the second data unit U2 to the sixth data unit U6 of the subsequent signal frame SF2 can be normally decoded. it can.
　図５Ｃに、比較例による通信システムの複数のデータ送信装置１０（図１）から送信される信号フレームＳＦ３、ＳＦ４のタイミングチャートの一例を示す。比較例においては、データユニットＵ１～Ｕ６が、同一の拡散コードＳＣ１を用いてスペクトラム拡散変調されている。先行する信号フレームＳＦ３と、後続の信号フレームＳＦ４との時間的な関係は、図５Ｂに示した先行する信号フレームＳＦ１と後続の信号フレームＳＦ２との関係と同一である。すなわち、先行する信号フレームＳＦ３の２番目のデータユニットＵ２と、後続の信号フレームＳＦ４の１番目のデータユニットＵ１とが、時間軸上で部分的に重なっている。 FIG. 5C shows an example of a timing chart of the signal frames SF3 and SF4 transmitted from the plurality of data transmission apparatuses 10 (FIG. 1) of the communication system according to the comparative example. In the comparative example, the data units U1 to U6 are spread spectrum modulated using the same spreading code SC1. The temporal relationship between the preceding signal frame SF3 and the subsequent signal frame SF4 is the same as the relationship between the preceding signal frame SF1 and the subsequent signal frame SF2 shown in FIG. 5B. That is, the second data unit U2 of the preceding signal frame SF3 and the first data unit U1 of the subsequent signal frame SF4 partially overlap on the time axis.
　先行する信号フレームＳＦ３の２番目のデータユニットＵ２と、後続の信号フレームＳＦ４の１番目のデータユニットＵ１とが、同一の拡散コードＳＣ１を用いてスペクトラム拡散変調されているため、先行の信号フレームＳＦ３の２番目のデータユニットＵ２と、後続の信号フレームＳＦ４の１番目のデータユニットＵ１とを検出することが困難である。 Since the second data unit U2 of the preceding signal frame SF3 and the first data unit U1 of the succeeding signal frame SF4 are spread spectrum modulated using the same spreading code SC1, the preceding signal frame SF3 It is difficult to detect the second data unit U2 and the first data unit U1 of the subsequent signal frame SF4.
　図５Ｄに示すように、先行の信号フレームＳＦ３の６番目のデータユニットＵ６と、後続の信号フレームＳＦ４の１番目のデータユニットＵ１とが部分的に重なっている場合でも、両者を正常に復号することが困難である。 As shown in FIG. 5D, even when the sixth data unit U6 of the preceding signal frame SF3 and the first data unit U1 of the succeeding signal frame SF4 partially overlap, both are normally decoded. Is difficult.
　実施例においては、図５Ｂに示したように、２つの信号フレームＳＦ１、ＳＦ２が重なっても、同一のデータユニット同士が重なっていなければ、２つの信号フレームＳＦ１、ＳＦ２を復号することが可能である。これに対し、図５Ｃ及び図５Ｄに示した比較例では、図５Ｄに示したように、２つの信号フレームＳＦ３、ＳＦ４が、フレーム全体の一部分でも重なっていれば、２つの信号フレームＳＦ３、ＳＦ４を正常に復号することが困難である。 In the embodiment, as shown in FIG. 5B, even if two signal frames SF1 and SF2 overlap, if the same data unit does not overlap, it is possible to decode the two signal frames SF1 and SF2. is there. On the other hand, in the comparative example shown in FIGS. 5C and 5D, as shown in FIG. 5D, if the two signal frames SF3 and SF4 overlap even a part of the whole frame, the two signal frames SF3 and SF4 are overlapped. Is difficult to decrypt normally.
　上述のように、実施例による通信システムにおいては、比較例による通信システムに比べて、復号不能な信号衝突の確率を低減させることができる。一例として、ランダムなタイミングで送信動作を行うデータ送信装置１０の台数が３台、１つのデータユニットの時間長が０．０５秒の条件の下で、実施例による通信システムにおいて、３０秒の間に１回の割合で各送信装置が送信動作を行う場合に復号不能な信号衝突が発生する確率は約１％である。これに対し、図５Ｃ及び図５Ｄに示した比較例による通信システムでは、同一の条件の下で、復号不能な信号衝突が発生する確率は約６％である。 As described above, in the communication system according to the embodiment, the probability of signal collision that cannot be decoded can be reduced as compared with the communication system according to the comparative example. As an example, in the communication system according to the embodiment, the number of data transmission devices 10 that perform transmission operation at random timing is three, and the time length of one data unit is 0.05 seconds. When each transmitting apparatus performs a transmission operation at a rate of once, the probability that a signal collision that cannot be decoded occurs is about 1%. On the other hand, in the communication system according to the comparative example shown in FIG. 5C and FIG. 5D, the probability that a signal collision that cannot be decoded occurs under the same condition is about 6%.
　上述のように、実施例による通信システムにおいては、信号の衝突に起因する通信障害の発生を抑制することができる。 As described above, in the communication system according to the embodiment, it is possible to suppress the occurrence of communication failure due to signal collision.
　また、上記実施例では、データユニットＵ１～Ｕ６に用いられる拡散コードＳＣ１～ＳＣ６は固定されている。従って、データ受信装置３０（図１）がデータ送信装置１０（図１）に、使用すべき拡散コードを指令する必要がない。このため、データ送信装置１０に、信号の受信機能を持たせる必要がない。これにより、受信機能を持たせることによるコストの増加、及び消費電力の増大を回避することができる。 In the above embodiment, the spreading codes SC1 to SC6 used for the data units U1 to U6 are fixed. Therefore, it is not necessary for the data receiving device 30 (FIG. 1) to instruct the data transmitting device 10 (FIG. 1) about the spreading code to be used. For this reason, it is not necessary for the data transmitting apparatus 10 to have a signal receiving function. As a result, it is possible to avoid an increase in cost and an increase in power consumption due to the reception function.
　複数のデータ送信装置１０（図１）に、それぞれ固有の拡散コードを割り当てる通信システムでは、信号衝突に対する耐性が高い。ところが、この方式では、データ送信装置１０の台数が増えると、使用する拡散コードの個数も増やさなければならない。使用する拡散コードの個数が増えると、データ受信装置３０において、使用する拡散コードの増加に対応して、復号処理のルーチンを増やさなければならない。 In a communication system in which a unique spreading code is assigned to each of a plurality of data transmission apparatuses 10 (FIG. 1), the resistance to signal collision is high. However, in this method, when the number of data transmission apparatuses 10 increases, the number of spreading codes to be used must also be increased. When the number of spreading codes to be used increases, the data receiving device 30 has to increase the number of decoding processing routines corresponding to the increase in the spreading codes to be used.
　上記実施例による通信システムにおいては、使用する拡散コードの個数は、フレームを構成するデータユニットＵ１～Ｕ６の個数で決まる。データ送信装置１０の台数が増えても、使用する拡散コードの個数を増やす必要はない。このため、データ送信装置１０の台数が増えても、データ受信装置３０に準備すべき復号処理のルーチンの個数を増やす必要はない。 In the communication system according to the above embodiment, the number of spreading codes to be used is determined by the number of data units U1 to U6 constituting the frame. Even if the number of data transmission devices 10 increases, it is not necessary to increase the number of spreading codes to be used. For this reason, even if the number of data transmitting apparatuses 10 increases, it is not necessary to increase the number of decoding processing routines to be prepared in the data receiving apparatus 30.
　以上実施例に沿って本発明を説明したが、本発明はこれらに制限されるものではない。例えば、種々の変更、改良、組み合わせ等が可能なことは当業者に自明であろう。 Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.
１０　データ送信装置
１１　送信データ
１２　拡散コード発生部
１４　スペクトラム拡散変調部
１６　搬送波発生部
１８　オンオフ変調部
１９　アンテナ
２０　プリアンブルフィールド
２１　データフィールド
２３　フラグ探索区間
３０　データ受信装置
３５、３６　相関演算結果を示すグラフ
ＣＷ　搬送波
Ｆ１　第１のフラグ
Ｆ２　第２のフラグ
ＭＳ　変調信号
ＳＣ、ＳＣ１～ＳＣ６　拡散コード
ＳＦ、ＳＦ１～ＳＦ４　信号フレーム
Ｕ１～Ｕ６　データユニット DESCRIPTION OF SYMBOLS 10 Data transmitter 11 Transmission data 12 Spread code generator 14 Spread spectrum modulator 16 Carrier generator 18 On-off modulator 19 Antenna 20 Preamble field 21 Data field 23 Flag search section 30 Data receiver 35, 36 Graph showing correlation calculation results CW carrier wave F1 first flag F2 second flag MS modulation signal SC, SC1 to SC6 spreading code SF, SF1 to SF4 signal frame U1 to U6 data unit

Claims (7)

  1. 　信号を送信する複数のデータ送信装置と、
    　複数の前記データ送信装置から送信された前記信号を受信するデータ受信装置と
    を有し、
    　前記データ送信装置の各々から送信される前記信号は、拡散コードを用いてスペクトラム拡散変調を行う単位となる複数のデータユニットが時間軸上に並ぶフレームフォーマットを有し、１つの前記フレームフォーマット内で相互に隣り合う前記データユニットは、相互に直交する拡散コードを用いてスペクトラム拡散変調されており、
    　１つの前記フレームフォーマットに含まれる前記データユニットの個数は、複数の前記データ送信装置において同一であり、
    　複数の前記データ送信装置から送信される前記信号の前記フレームフォーマットの、対応する位置の前記データユニットが、同一の前記拡散コードを用いてスペクトラム拡散変調されている通信システム。     A plurality of data transmission devices for transmitting signals;
    A data receiving device that receives the signals transmitted from a plurality of the data transmitting devices,
    The signal transmitted from each of the data transmission devices has a frame format in which a plurality of data units, which are units for performing spread spectrum modulation using a spreading code, are arranged on the time axis, and within one frame format The data units adjacent to each other are spread spectrum modulated using spreading codes orthogonal to each other,
    The number of the data units included in one frame format is the same in a plurality of the data transmission devices,
    A communication system in which the data units at corresponding positions in the frame format of the signals transmitted from a plurality of the data transmission devices are subjected to spread spectrum modulation using the same spreading code.
  2. 　１つの前記フレームフォーマット内の複数の前記データユニットのスペクトラム拡散変調に用いられる前記拡散コードは、すべて異なり、相互に直交する請求項１に記載の通信システム。 The communication system according to claim 1, wherein the spread codes used for spread spectrum modulation of the plurality of data units in one frame format are all different and orthogonal to each other.
  3. 　前記データ送信装置は、前記信号を送信する機能を有するが、前記データ受信装置からの信号を受信する機能を持たない請求項１または２に記載の通信システム。 The communication system according to claim 1 or 2, wherein the data transmission device has a function of transmitting the signal but does not have a function of receiving a signal from the data reception device.
  4. 　複数の前記データ送信装置は、相互に独立して前記信号を送信する請求項１乃至３のいずれか１項に記載の通信システム。 The communication system according to any one of claims 1 to 3, wherein a plurality of the data transmission devices transmit the signals independently of each other.
  5. 　搬送波を発生する搬送波発生部と、
    　変調信号を発生するスペクトラム拡散変調部と、
    　前記変調信号に基づいて、前記搬送波を変調する変調部と、
    　前記変調部で変調された信号を、データ受信装置に送信するアンテナと
    を有し、
    　前記変調信号は、拡散コードを用いてスペクトラム拡散変調を行う単位となる複数のデータユニットが時間軸上に並ぶフレームフォーマットを有し、１つの前記フレームフォーマット内で相互に隣り合う前記データユニットは、相互に直交する拡散コードを用いてスペクトラム拡散変調されているデータ送信装置。     A carrier generation unit for generating a carrier;
    A spread spectrum modulation section for generating a modulation signal;
    A modulation unit that modulates the carrier wave based on the modulation signal;
    An antenna for transmitting the signal modulated by the modulation unit to a data receiving device;
    The modulation signal has a frame format in which a plurality of data units serving as units for performing spread spectrum modulation using a spreading code are arranged on a time axis, and the data units adjacent to each other in one frame format are: A data transmission apparatus that is spread spectrum modulated using spreading codes that are orthogonal to each other.
  6. 　１つの前記フレームフォーマット内の複数の前記データユニットのスペクトラム拡散変調に用いられる前記拡散コードは、すべて異なり、相互に直交する請求項５に記載のデータ送信装置。 6. The data transmission apparatus according to claim 5, wherein the spread codes used for spread spectrum modulation of a plurality of the data units in one frame format are all different and orthogonal to each other.
  7. 　信号を受信する機能を持たない請求項５または６に記載のデータ送信装置。 The data transmission device according to claim 5 or 6, wherein the data transmission device does not have a function of receiving a signal.
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