JP4928996B2 - Wireless communication apparatus and system - Google Patents

Description

  The present invention relates to a wireless communication apparatus and a wireless communication system, and more particularly to a wireless communication system in which a plurality of terminals form one network.

In a conventional wireless ad hoc network, for example, when a parent terminal selects a parent terminal candidate from a plurality of child terminals and communicates the priority order, if the broadcast signal is not broadcast for a predetermined time, the parent terminal candidate has priority. It becomes a new parent terminal according to the rank and transmits a notification signal. By doing in this way, the period when a parent terminal does not exist can be shortened, and the terminal which wants to participate in a network can start communication with a parent terminal immediately (for example, refer patent document 1).
JP 2005-6327 A

  In a system that assumes a broadband system of several gigahertz and does not know where the notification signal is transmitted, in order to specify the frequency of the notification signal and its information, a method of sequentially scanning a narrow band, Although there are methods for obtaining a spreading gain, it takes time to specify a broadcast signal. If an attempt is made to receive a notification signal without taking a long time, the probability of reception failure increases, and a terminal that wants to newly join the network cannot receive the notification signal and starts operating as a parent terminal. That is, in general ad hoc communication, a terminal that wants to newly join a network first searches for a parent terminal. If the parent terminal cannot be found, the terminal itself becomes the parent terminal. For this reason, when the network load is high and the reception operation time of the parent terminal is long, the parent terminal may be disturbed and the system throughput of the network may be significantly reduced.

  The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide a wireless communication apparatus and system capable of improving the system throughput of a network.

A communication method as one aspect of the present invention includes:
The first wireless communication device transmits a beacon and a first notification signal including frequency information of the beacon,
A 2nd radio | wireless communication apparatus transmits the 2nd alerting | reporting signal containing the frequency information of the said beacon with the frequency different from a said 1st alerting | reporting signal.
A communication method as one aspect of the present invention includes:
The first wireless communication device transmits a beacon and a first notification signal including frequency information of the beacon,
A 2nd radio | wireless communication apparatus transmits the 2nd alerting | reporting signal containing the frequency information of the said beacon with the same frequency as a said 1st alerting | reporting signal.

A wireless communication system as one aspect of the present invention includes:
First transmission means for transmitting a beacon;
Second transmitting means for transmitting a first notification signal including frequency information of the beacon;
A first wireless communication device including:
A second wireless communication device including: a third transmission unit configured to transmit a second notification signal including frequency information of the beacon at a frequency different from that of the first notification signal.

A wireless communication device according to an aspect of the present invention includes:
Communication means for communicating with a first wireless communication device for transmitting a beacon and a first notification signal including frequency information of the beacon;
Transmitting means for transmitting a second notification signal including frequency information of the beacon at a frequency different from that of the first notification signal;
Is provided.

  According to the wireless communication apparatus and system of the present invention, the system throughput of the network can be improved.

  Hereinafter, embodiments of the present invention will be described.

Hereinafter, a wireless communication apparatus and system according to embodiments of the present invention will be described in detail with reference to the drawings. Note that the wireless communication device may be referred to as a terminal.
FIG. 1 shows a system configuration example of the present embodiment. Terminals 101 to 107 form one network (hereinafter also referred to as a system) and can communicate data with each other using signals in a communication frequency band (hereinafter referred to as a main band). Here, the terminal 101 operates as a parent terminal. The parent terminal transmits a notification signal and a beacon for a terminal newly joining the network. Each terminal in the network transmits a data communication signal at a frequency and time slot specified by the parent terminal.

  FIG. 2 shows a conceptual diagram of a notification signal and a beacon transmitted from the parent terminal. The broadcast signal 201 is a signal that can be demodulated when a terminal newly joining the network continuously receives a relatively long time (for example, several tens of frames: 1 frame is 4 ms), and is transmitted from the parent terminal. Information on the frequency and timing of the beacon 202. The beacon transmitted from the parent terminal includes network-specific information, and a terminal that wants to participate in the network uses this information to make a network participation request to the parent terminal. The beacon is transmitted once per frame by the parent terminal. The parent terminal 101 and the child terminal 102 to the child terminal 107 perform data communication 203 using a frequency or time different from the notification signal 201 and the beacon 202. Data communication 203 is used for communication within the same network.

  The parent terminal 101 selects a broadcast signal transmitting terminal from among the child terminals in the network. The selection method will be described later with reference to FIG. 6, FIG. 7, and FIG. The opportunity to select may be made periodically or when the terminal newly joins the network. Here, it is assumed that the parent terminal 101 has selected the child terminal 103 and the child terminal 104 as broadcast signal transmission terminals. The parent terminal 101 notifies the notification signal transmission instruction information 108 and 109 to the child terminal 103 and the child terminal 104 selected as the notification signal transmission terminal. The notification signal transmission instruction information includes information necessary for the notified child terminal to transmit the notification signal. Here, it is assumed that the notification signal transmission instruction information includes the ID of the other party to be notified, the timing for transmitting the notification signal, the period, and the transmission length. Examples of other information include a frequency band, a frequency hopping pattern, and a spreading code at which the broadcast signal transmitting terminal transmits the broadcast signal. Receiving the notification signal transmission instruction information 108 and 109, the child terminals 103 and 104 become notification signal transmission terminals and start transmitting the notification signal according to the instruction information. In addition, when changing the notification signal transmission terminal, the notification signal transmission instruction corresponding to the notification signal stop instruction information for the parent terminal to return from the notification signal transmission terminal to the normal child terminal is similar to the notification signal transmission instruction information. Send to the terminal.

  FIG. 3 shows a specific example of the notification signal. The notification signal 201 in FIG. 3 is the same as the notification signal 201 in FIG. The notification signal 201 includes two narrow band signals 301 and 302. The narrowband signals 301 and 302 are, for example, ASK (Amplitude Shift Keying) signals, and transmit the same baseband signal simultaneously in two frequency bands separated by a frequency of Δf. When using PSK (Phase Shift Keying), transmission is performed using differential phase modulation in which information is added to the phase difference between one signal and the other. Δf is a value unique to the system, and each terminal has a known value. The child terminal receives the cross-correlation between the narrowband signals 301 and 302.

  4 and 5 show the relationship between the notification signal transmitted by the parent terminal and the notification signal transmitted by the notification signal transmitting terminal. In particular, the relationship shown in FIG. 4 is a major feature of the embodiment of the present invention.

  In FIG. 4, the notification signal 401 of the parent terminal 101 and the notification signals 405 and 406 of the notification signal transmission terminals 103 and 104 are transmitted simultaneously at different frequencies, that is, in parallel. The notification signal 401 and the set of the notification signals 405 and 406 include the same information (frequency and timing information of the beacon 202). That is, a set of notification signals 405 and 406 including the same information as the notification signal 401 is transmitted by two notification signal transmission terminals in a time division manner. That is, the notification signal transmission instruction information 108 and 109 transmitted from the parent terminal 101 to the notification signal transmission terminals 103 and 104 includes the same information as the notification signal 401 in parallel with the transmission of the notification signal 401 by the parent terminal 101. An instruction to transmit the notification signal in time division by the notification signal transmission terminals 103 and 104 is included. As described above, the notification signal transmission instruction information includes the timing, period, transmission length, frequency band, and the like of transmitting the notification signal. Therefore, in parallel with the transmission of the notification signal by the parent terminal 101, 2 Two broadcast signal transmitting terminals can transmit broadcast signals in a time division manner. In this example, the two notification signal transmitting terminals 103 and 104 transmit the notification signal in a time division manner, but the parent terminal 101 transmits the notification signal transmission instruction information to only one notification signal transmitting terminal. Only one notification signal transmitting terminal may transmit the notification signal in parallel with the transmission of the notification signal by the parent terminal. Here, the notification signal transmission terminal 103 that transmits the notification signal 405 cannot receive the data communication signal 403 because the transmission signal thereof becomes interference. Similarly, it is very difficult for the notification signal transmitting terminal 104 that transmits the notification signal 406 to receive the data communication signal 404. For this reason, it is necessary to assign slots so that one terminal does not transmit and receive at the same time.

  The notification signal 401 and the notification signals 405 and 406 notify the frequency and timing of the beacon 402 over several tens of frames. During this time, even when the interference signal 407 is generated and the parent terminal 101 has to stop the notification signal 401, the notification signal 406 of the notification signal transmission terminal 104 is continuously transmitted. That is, even if it becomes difficult for the child terminal to receive the notification signal of the parent terminal 101, the child terminal can receive the notification signal because there is the notification signal transmitting terminal 104. Therefore, a terminal that newly joins the network can receive the beacon 402 without having to redo the reception of the notification signal from the beginning. When the terminal 101 detects the occurrence of the interference signal 407, the terminal 101 stops transmission in the frequency band (transmission of the notification signal 401), performs carrier sense in the main band, and then again transmits the notification signal in the band without the interference signal. Start sending. Note that it may be difficult for the child terminal to receive the notification signal from the parent terminal depending not only on the interference but also on the position of the parent terminal. Assuming such a case, it is desirable that the notification signal transmitting terminal 104 is located far from the parent terminal.

  In FIG. 5, the notification signal 501 of the parent terminal 101 and the notification signals 505 and 506 of the notification signal transmission terminals 103 and 104 are transmitted in a time division manner. Data communication signals 503 and 504 are signals transmitted from the child terminal and received by the parent terminal 101. Here, it is assumed that the data communication signals 503 and 504 are transmitted by the notification signal transmitting terminals 103 and 104. At this time, when the parent terminal 101 receives the data communication signal 503 and the data communication signal 504, if the notification signal 501 is transmitted, the transmission signal transmitted by the parent terminal 101 is transmitted to the receiving side of the parent terminal 101. It becomes difficult to receive signals due to large interference. For this reason, the parent terminal 101 does not transmit the notification signal during the reception operation, and instructs the selected notification signal transmission terminals 103 and 104 to transmit the notification signal during the reception operation of the parent terminal. By issuing such an instruction, the parent terminal 101 and the notification signal transmission terminals 103 and 104 transmit the notification signal in a time division manner.

  The notification signal 501 and the notification signals 505 and 506 notify the frequency and timing of the beacon 502 over several tens of frames. In FIG. 5, the notification signal 501 of the parent terminal and the notification signals 505 and 506 of the notification signal transmitting terminal are transmitted at different frequencies, but may be transmitted at the same frequency. During this time, when the parent terminal 101 receives the data communication signals 503 and 504, even if the notification signal is transmitted from the notification signal transmitting terminal in a time-division manner even when the transmission of the notification signal has to be stopped. Since it is continuously transmitted, a terminal newly participating in the network can receive the beacon 502 without having to restart reception of the notification signal from the beginning. Assuming such a case, it is desirable that the notification signal transmitting terminal 104 is located near the parent terminal.

  4 and 5 show an example in which a notification signal that can be received by the terminal is transmitted even if the terminal does not know the frequency band in which the notification signal is transmitted. In addition to this, there may be a case where a notification signal that cannot be received unless the terminal knows the frequency band in which the notification signal is transmitted is transmitted. At this time, even if the notification signal transmitted by the parent terminal is stopped when the notification signal transmitting terminal transmits the notification signal in the same frequency band as the notification signal transmitted by the parent terminal, the terminal that wants to participate in the network Can receive the notification signal. However, in this case, it is assumed that the terminal that wants to participate in the network knows the frequency band of the broadcast signal transmitted by the parent terminal. Such a notification signal that the terminal cannot receive without knowing the frequency and a notification signal that can be received without knowing the frequency band in which the notification signal is transmitted may exist simultaneously. Further, the notification signal described with reference to FIGS. 4 and 5 may be applied to any notification signal.

  FIG. 6 shows a sequence diagram when the parent terminal determines whether or not the child terminal becomes a notification signal transmitting terminal when participating in the network. The terminals 611 and 612 that have not yet joined the network of the parent terminal 610 receive the notification signal transmitted by the parent terminal or the notification signal transmission terminal, and receive the beacon transmitted by the parent terminal, thereby obtaining network information. It shall be. When a request for participation in the network, that is, a request for channel assignment for data communication occurs in the child terminal 611, the child terminal 611 notifies the parent terminal 610 of a request for participation in the network (step S601). Receiving the network participation request, the parent terminal 610 performs broadcast signal transmission terminal selection processing using signal power or the like (step S602). In the broadcast signal transmission terminal selection process, the parent terminal 610 measures the signal power of the network participation request signal, estimates the distance from the child terminal based on the magnitude, and determines the child located at a desired distance depending on the processing content. Select a terminal. The broadcast signal transmission terminal selection process will be described later with reference to FIG. In this example, the case where the terminal 611 is not designated as the broadcast signal transmitting terminal is shown. In this case, the parent terminal 610 notifies only the answer regarding the network participation request. Here, the permission notification regarding the network participation request is notified to the child terminal 611 (step S603).

  Next, it is assumed that a request for participation in the network is generated in the child terminal 612 and the request for participation in the network is notified to the parent terminal 610 (step S604). At this time, the parent terminal 610 performs notification signal transmission terminal selection processing in the same manner as described above (step S605). Here, when the parent terminal 610 determines to select the child terminal 612 as the notification signal transmission terminal, the parent terminal 610 notifies the child terminal 612 of permission notification regarding the network participation request (step S606), and notification signal transmission instruction information Is also notified (step S607).

  The broadcast signal transmission instruction information may include information such as information to be carried on the broadcast signal, frequency band, spreading code, beam direction, transmission power, etc. in addition to the broadcast signal timing information to be transmitted by the child terminal 612. The notification signal transmission timing may specify the timing at which the parent terminal 610 performs the reception operation so that the child terminal 612 transmits the notification signal during the reception operation of the parent terminal 610. In addition, in consideration of the case where the parent terminal 610 stops the notification signal due to the generation of an interference signal or the like, the parent terminal 610 may be specified to be transmitted in time division with other notification signal transmission terminals. When a frequency band is specified, if a frequency band having a low frequency correlation with the frequency band of the notification signal transmitted by the parent terminal 610 is specified, the possibility that the notification signal cannot be transmitted simultaneously when an interference signal is generated can be reduced. When designating the beam direction, it is possible to prevent the terminal from receiving the beacon of the parent terminal 610 from receiving the notification signal by directing the beam toward the center of the network or toward the parent terminal. The notification signal transmission instruction information is transmitted from the parent terminal 610 by, for example, a beacon or a data communication signal.

  The terminal 612 that has received the notification signal transmission instruction information performs notification signal transmission start processing according to the content of the notification signal transmission instruction information (step S608). If there is no clear instruction of the frequency band for transmitting the notification signal in the notification signal transmission instruction information, the child terminal 612 performs carrier sense in the main band and transmits the notification signal in a band in which no interference signal exists. The notification signal transmitted by the child terminal 612 includes information necessary for receiving the beacon transmitted by the parent terminal, similarly to the notification signal transmitted by the parent terminal.

  FIG. 7 shows a sequence diagram when the notification signal transmitting terminal is periodically selected from the child terminals. It is assumed that child terminal 711 and child terminal 712 have already joined the network of parent terminal 710 and have been assigned channels for data communication. The child terminal 711 and the child terminal 712 periodically transmit a measurement packet for the parent terminal to estimate the signal power and the arrival direction (steps S701 and S703). It is desirable to use a known signal for the measurement packet so that power measurement is easy. In addition, when a narrowband signal is transmitted, the power may be significantly reduced due to frequency selective fading. Therefore, the signal may be a wideband signal or a plurality of narrowband signals may be transmitted using several frequency bands. You may do it. For example, the parent terminal 710 estimates the reception power and arrival direction of a known signal and selects a desired child terminal.

  The parent terminal 710 that has received the measurement packet from the child terminal 711 performs broadcast signal transmission terminal selection processing (step S702), and determines whether or not the child terminal 711 should be selected as the broadcast signal transmission terminal. Here, the parent terminal 710 determines that the child terminal 711 should not be selected as the notification signal transmission terminal, and no subsequent action is taken. The parent terminal 710 that has received the measurement packet 603 from the child terminal 712 similarly performs notification signal transmission terminal selection processing (step S704), and determines that the parent terminal 710 should select the child terminal 712 as the notification signal transmission terminal. And At this time, the parent terminal 710 transmits notification signal transmission instruction information to the child terminal 712 (step S705), and the child terminal 712 that has received the notification signal transmission instruction information performs notification signal transmission start processing according to the instruction (step S705). S706). Note that the broadcast signal transmission instruction information also includes information on whether the broadcast signal is transmitted simultaneously at different frequencies as illustrated in FIG. 4 or whether the broadcast signal is transmitted in time division as illustrated in FIG.

FIG. 8 shows a block diagram of an example of a wireless communication apparatus.
First, each part will be described along the receiving operation. A radio frequency signal received from the antenna 812 is converted from a radio frequency signal to a baseband signal having a main band frequency bandwidth by the RF / IF processing unit 801. The baseband signal is converted into a digital signal by the ADC 802.

  The power measurement processing unit 803 is used to measure the signal power of the signal from the child terminal when operating as the parent terminal. The signal power from the child terminal is calculated using, for example, RSSI (received-signal intensity) of the signal band. The measurement timing is notified from the control processing unit 806 when a network participation request is received from a child terminal or when a power measurement packet is received. Here, it is assumed that the power measurement packet is periodically transmitted from the child terminal, and the control processing unit 806 knows its cycle. The measured signal power is stored in a terminal category DB (DB: database) 811 via the control processing unit 806.

  The notification signal reception processing unit 804 is used to receive a notification signal from the parent terminal when the terminal operates as a child terminal. Information of the notification signal obtained by the notification signal reception processing unit 804, that is, information such as frequency and timing necessary for receiving the beacon of the parent terminal is notified to the control processing unit 806.

  The data signal reception processing unit 805 is used when receiving transmission signal from the parent terminal or the child terminal or a beacon from the parent terminal or receiving the notification signal transmission instruction information. When receiving a beacon, information necessary for receiving the beacon is received from the control processing unit 806, and after receiving the beacon, information necessary for network participation included in the beacon and slot allocation information for data communication are transmitted to the control processing unit. 806 is notified. When receiving transmission data from a parent terminal or a child terminal, slot allocation information is received from the control processing unit 806, and reception processing is performed in accordance with the received slot allocation information.

Next, each part will be described along the transmission operation.
The broadcast signal transmission processing unit 809 creates a broadcast signal and transmits it to the DAC 808 when the terminal is operating as a parent terminal. The beacon information to be put on the notification signal is received from the control processing unit 806.

  The data signal transmission processing unit 810 receives data from the control processing unit 806 and performs data transmission to the parent terminal or the child terminal, beacon transmission, and the like. Signals output from the notification signal transmission processing unit 809 and the data signal transmission processing unit 810 are converted into analog signals by the DAC 808, converted into radio frequency signals by the RF / IF processing unit 807, and then output from the antenna 812.

In addition to the above processing, the control processing unit 806 performs data exchange with a higher layer and broadcast signal transmission terminal determination processing.
The terminal category database 811 stores information on child terminals in the network when operating as a parent terminal.

FIG. 9 shows a block diagram of an example of the notification signal reception processing unit 804.
The signal input from the ADC 802 is converted in frequency by Δf in the complex multiplication processing unit 901. Thereafter, the complex conjugate processor 902 takes the complex conjugate, and the complex multiplier 903 multiplies the input signal from the ADC 802 and the complex conjugate signal. In this way, a phase difference vector between the two narrowband signals 301 and 302 in FIG. 3 is obtained. By passing this through an LPF (Low Pass Filter) 904 that matches the symbol band of the broadcast signal, a reception result for the signal transmitted from the parent terminal can be obtained. The matched filter 905 performs matched filter processing on this result, thereby establishing synchronization and obtaining information on the notification signal.

  By adopting this configuration, the child terminal can receive the broadcast signal without knowing which frequency band broadcast signal in the main band exists. Even if a plurality of terminals transmit a notification signal, if the content of the notification signal is the same and Δf is equal, reception is possible without particular awareness. For this reason, the notification signal transmitting terminal can transmit the notification signal at an arbitrary frequency.

FIG. 10 shows an example of database information held by the parent terminal.
The parent terminal has a database (terminal category database 811) registered for the child terminals in the network. The terminal category database 811 registers received power from the child terminal, priority for becoming a broadcast signal transmission terminal of the child terminal, and broadcast signal transmission terminal type information.

  Received power is ranked according to its strength. Here, grouping is performed in five stages from 1 to 5, and 5 is a terminal having the strongest power. If the terminal is a system that performs transmission power control, it is necessary to normalize using the transmission power of the child terminal.

  The priority is an index indicating whether or not the child terminal is suitable as a broadcast signal transmitting terminal, and is determined by the parent terminal using a certain standard, or the child terminal notifies the parent terminal. Here, grouping is performed in six stages from 0 to 5, where 0 is a terminal that cannot transmit a broadcast signal, and 5 is a child terminal that is most likely to be a broadcast signal transmission terminal. Here, when an example of a child terminal that is likely to be a notification signal transmitting terminal is given, for example, it is a power supply continuation time, and the priority changes depending on a time during which power can be continuously supplied. For example, a terminal that is connected to an AC power source and does not need to worry about power consumption has a higher priority. Conversely, a terminal that has a battery operation and a low battery level has a low priority. In addition, as a result of interference detection in the main band performed by the terminal, the priority is lowered in a terminal where interference is frequently detected, and the priority is set in a terminal in which interference is not detected for a long time in one frequency band in the main band. Make it high.

  The broadcast signal transmitting terminal type indicates how the broadcast signal transmitting terminal transmits the broadcast signal. For example, a terminal registered as “Freq” uses a frequency different from that of the parent terminal as shown in FIG. 4 in a case where the parent terminal cannot transmit the notification signal due to the interference signal. At the same time, a notification signal is transmitted. In consideration of the case where the terminal registered as “Time” cannot transmit the notification signal during the receiving operation, the terminal transmits the notification signal in time division with the notification signal of the parent terminal as shown in FIG. Yes.

FIG. 11 shows an example of a flow for the parent terminal to update the database value and determine the broadcast signal transmitting terminal. This operation is performed in steps S602, S605, S702, and S704.
First, the parent terminal measures the signal power from the child terminal (step S1101). For this signal power measurement, a network participation request signal from a child terminal may be used, or a power measurement packet may be used. Next, the value of the terminal category database 811 is updated according to the measured signal power (step S1102). Using the update result, N terminals with high received power (N is an integer of 1 or more) are selected as the notification terminal 1 from terminals having a priority of 1 or more (step S1103). That is, a terminal located near the parent terminal is selected. Here, the notification terminal 1 is a terminal that transmits a notification signal in a time division manner with the notification signal of the parent terminal in consideration of the case where the parent terminal cannot transmit the notification signal during the reception operation. If the received power is in the same category and there are N or more, a terminal with a higher priority is selected.

  Furthermore, using the update result, M terminals (M is an integer equal to or greater than 1) with low received power are selected as the notification terminal 2 from terminals having a priority of 1 or greater (step S1104). That is, a terminal located far from the parent terminal is selected. Here, the notification terminal 2 is a terminal that transmits a notification signal at the same time as the notification signal of the parent terminal using a frequency different from that of the parent terminal, in case the parent terminal cannot transmit the notification signal due to the interference signal. is there. If the received power is in the same category and there are M or more, a terminal with a higher priority is selected. Finally, if there is a change in the notification terminal column of the database, notification signal transmission instruction information or notification signal stop instruction information is notified to the corresponding terminal (step S1105).

  In the case of the terminal arrangement as shown in FIG. 12, how the database and the broadcast signal transmitting terminal change will be specifically described.

  Assume that the parent terminal has a terminal category database 811 as shown in FIG. 10, and terminals A to F operate as child terminals. Further, it is assumed that N = 1 and M = 2. When the terminal G notifies the parent terminal of the network participation request, the parent terminal uses the network participation request to measure the received power and determine its category, and also uses the terminal status included in the network participation request. Determine the priority category. Using this information, the terminal category database 811 is updated. The parent terminal further enters a determination process for a broadcast signal transmitting terminal.

  As shown in FIG. 13, when the signal power of the terminal G is 1 and the priority is 2, the received power is the lowest category and higher than the priority of the terminal F. Signal 2 is “Freq”), and the terminal F is changed from the broadcast signal transmitting terminal to a normal child terminal. As a result, a notification signal stop notification is transmitted to terminal F, and a notification signal transmission notification is transmitted to terminal G.

FIG. 14 shows a block diagram of another example of the wireless communication apparatus. In the following, the same parts as those already described are designated by the same reference numerals and the description thereof is omitted.
First, each unit will be described along the receiving operation. In FIG. 14, four antennas are illustrated, but it is sufficient that the number of antennas can create two or more patterns. If many are installed, the number of directivity patterns increases and it becomes easy to grasp the position of the terminal, but there are drawbacks such as an increase in the size of the wireless communication device.

  A radio frequency signal received from the antenna 812 is converted from a radio frequency signal to a baseband signal having a main band frequency bandwidth by the RF / IF processing unit 801. The baseband signal is converted into a digital signal by the ADC 802.

  In response to an instruction from the control processing unit 1402, the antenna directivity processing unit 1401 rotates the phase of the reception signal and adds the respective signals, thereby outputting a reception signal with enhanced antenna directivity according to the instruction. The power measurement processing unit 803 is used to measure the signal power from the child terminal when operating as the parent terminal. The signal power from the child terminal is calculated using, for example, RSSI of the signal band. The measurement timing is notified from the control processing unit 1402 when a network participation request is received from a child terminal or when a power measurement packet is received. Here, it is assumed that the power measurement packet is periodically transmitted from the child terminal, and the control processing unit 1402 knows its cycle. The measured signal power is stored in the terminal category DB 1403 via the control processing unit 1402.

  The notification signal reception processing unit 804 is used to receive a notification signal from the parent terminal when the terminal operates as a child terminal. Data of the notification signal obtained by the notification signal reception processing unit 804, that is, information such as frequency and timing necessary for receiving the beacon of the parent terminal is notified to the control processing unit 1402. When the notification signal reception processing unit 804 performs notification signal reception processing, the antenna directivity processing unit 1401 is preferably controlled to be omni (omnidirectional).

  The data signal reception processing unit 805 is used when receiving transmission data from the parent terminal or the child terminal and a beacon from the parent terminal. When receiving a beacon, information necessary for receiving the beacon is received from the control processing unit 1402, and after receiving the beacon, the data signal reception processing unit 805 is used for information necessary for network participation included in the beacon and data communication. The slot allocation information is notified to the control processing unit 1402. When receiving transmission data from the parent terminal or the child terminal, the data signal reception processing unit 805 receives the slot allocation information from the control processing unit 1402 and performs reception processing according to this.

  Next, each unit will be described along the transmission operation. Broadcast signal transmission processing section 809 creates a broadcast signal and transmits it to antenna directivity processing section 1404 when the terminal is operating as a parent terminal or broadcast signal transmission terminal. The beacon information to be put on the notification signal is received from the control processing unit 1402 by the notification signal transmission processing unit 809. The data signal transmission processing unit 810 receives data from the control processing unit 1402 and performs data transmission to a parent terminal or a child terminal, beacon transmission, and the like. Signals output from the notification signal transmission processing unit 809 and the data signal transmission processing unit 810 are input to the antenna directivity processing unit 1404.

  Based on an instruction from the control processing unit 1402, the antenna directivity processing unit 1404 rotates the phase of the signal to the DAC 808 corresponding to each antenna and outputs it. For example, in the notification signal transmission process, in consideration of the case where the parent terminal becomes unable to transmit the notification signal during the receiving operation, when transmitting the notification signal in time division with the notification signal of the parent terminal, the directivity is not created, It is good to send to become omni. In addition, in the case where the parent terminal cannot transmit a notification signal due to an interference signal, when the notification signal is transmitted simultaneously with the notification signal of the parent terminal using a frequency different from that of the parent terminal, Forming the beam in the direction of the terminal can improve the system throughput without unnecessarily widening the network. At this time, the directivity parameter may be instructed by the parent terminal, or the broadcast signal transmitting terminal may estimate the beacon arrival direction using the arrival direction estimation technique, recognize the direction of the parent terminal, The sex parameter may be determined. A signal output from the antenna directivity processing unit 1404 is converted into an analog signal by the DAC 808, converted into a radio frequency signal by the RF / IF processing unit 807, and then output from the antenna 812.

  In the embodiment corresponding to FIG. 14, the antenna pattern is formed by digital signal processing, but may be performed by analog signal processing. Further, the antenna pattern may be formed by physically changing the direction of the antenna.

  In addition to the above processing, the control processing unit 1402 performs data exchange with an upper layer, broadcast signal transmission terminal determination processing, and antenna directivity determination processing. The terminal category database 1403 holds information on child terminals in the network when operating as a parent terminal.

FIG. 15 shows an example of database information held by the parent terminal (configuration shown in FIG. 14).
The parent terminal has a terminal category database 1403 registered for the child terminals in the network. Here, the received power from the child terminal, the priority for becoming the broadcast signal transmission terminal of the slave terminal, the broadcast signal transmission terminal Type information and classified antenna pattern groups are registered. Received power is ranked according to its strength. The received power is stored for each antenna pattern. Here, grouping is performed in five stages from 1 to 5, and 5 is a terminal having the strongest power. If the terminal is a system that performs transmission power control, it is necessary to normalize using the transmission power of the child terminal. The priority is an index indicating whether or not the child terminal is suitable as a broadcast signal transmitting terminal, and is determined by the parent terminal using a certain standard, or the child terminal notifies the parent terminal. Here, grouping is performed in six stages from 0 to 5, where 0 is a terminal that cannot transmit a broadcast signal, and 5 is a child terminal that is most likely to be a broadcast signal transmission terminal. Here, as an example of the ease of becoming a notification signal transmitting terminal, for example, a terminal that is connected to an AC power source and does not need to worry about power consumption has a higher priority, battery operation, and battery A terminal with a low remaining amount has a low priority. In addition, as a result of interference detection in the main band performed by the terminal, the priority is lowered in a terminal where interference is frequently detected, and the priority is set in a terminal in which interference is not detected for a long time in one frequency band in the main band. Make it high. The broadcast signal transmitting terminal type indicates how the broadcast signal transmitting terminal transmits the broadcast signal. For example, a terminal registered as “Freq” uses a frequency different from that of the parent terminal as shown in FIG. 4 in a case where the parent terminal cannot transmit the notification signal due to the interference signal. At the same time, a notification signal is transmitted. In consideration of the case where the terminal registered as “Time” cannot transmit the notification signal during the receiving operation, the terminal transmits the notification signal in time division with the notification signal of the parent terminal as shown in FIG. Yes.

FIG. 16 illustrates a reception power update method, antenna pattern grouping method, and broadcast signal transmission terminal selection method in the parent terminal database of FIG. In the present embodiment, it is assumed that the antenna pattern is an antenna pattern in which null is directed in one direction, and power is measured. Hereinafter, the same steps as those already described are denoted by the same reference numerals and description thereof is omitted.
First, before measuring the signal power from the child terminal, the parent terminal forms one of the antenna patterns that the parent terminal has (step S1601). When the signal power from the child terminal is measured using the network participation request signal, for example, when a signal such as a postamble following the network participation request is transmitted, an antenna pattern is formed. When the measurement is performed periodically, an antenna pattern is formed when a power measurement packet transmitted from the child terminal is received. After forming the antenna pattern, the signal power from the child terminal is received (step S1101). For this signal power measurement, a network participation request signal from a child terminal may be used, or a power measurement packet may be used. Next, the terminal category database 1403 is updated using the measured signal power value according to the antenna pattern (step S1102). These operations are performed for all antenna patterns (step S1602). For example, in the case of the database of FIG. 15, the loop is repeated five times from step S1601 to step S1602.

  When power measurement is completed for all antenna patterns (Yes in step S1602), antenna pattern grouping is performed using the database update result (step S1603). First, a terminal whose signal power is greatly reduced only for a specific antenna pattern is found. The terminal classifies the corresponding antenna pattern into a group of patterns, assuming that the terminal exists in the direction in which the null faces. Here, in determining whether or not the signal power is greatly reduced, for example, when there is a pattern indicating a low power of 20 dB or more from the average signal power of all patterns of the corresponding terminal, the null of the pattern is recommended. I think that there is a terminal in the direction. Also, if any pattern has the same power on average, it cannot be put into the antenna pattern group. Using this procedure, all terminals are classified.

  Among all the pattern groups, N terminals having high received power are selected as the notification terminal 1 from terminals having a priority of 1 or higher (step S1604). The notification terminal 1 is the same as described above.

  After that, for each group, M terminals with low received power are selected as the notification terminal 2 from terminals having a priority of 1 or higher (step S1605). The notification terminal 2 is the same as described above. Finally, if there is a change in the notification terminal column of the database, notification signal transmission instruction information or notification signal stop instruction information is notified to the corresponding terminal (step S1105). Note that although priority 1 or higher is set in steps S1604 and S1605, this may be determined as appropriate and need not be limited to priority 1.

In the case of the terminal arrangement as shown in FIG. 17, the antenna pattern and database update method will be specifically described.
It is assumed that the parent terminal has a database having the contents as shown in FIG. 15 and terminals A to G operate as child terminals. It is assumed that M = 1. The parent terminal forms several antenna patterns when the terminal transmits a power measurement packet. For example, four types of patterns 1 to 4 are formed: an omni pattern as shown by a circle in FIG. 17 and a pattern in which a null is directed in one direction as shown in FIGS. Each time these patterns are changed, the received power is measured using the power measurement packet from the terminal. When receiving a power measurement packet from the terminal B, the measured power is significantly reduced only when the antenna pattern 1 has a null facing the terminal B. In the example of FIG. 15, when the power from terminal B is measured with another antenna pattern, the received power is “3”, but only in the case of pattern 1, it is “0”. Therefore, the terminal B determines that the terminal exists in the direction in which the antenna pattern 1 is turned to null, and determines the pattern group as the pattern 1. Similarly, when the signal power is received by the antenna pattern 2, the signal power of the terminal C is decreased, so that the terminal C is classified into the pattern group 2. For terminal E and terminal G, in this example, since there is no antenna pattern in the null-facing direction, the received power is almost constant and no grouping is performed.

  After the grouping is performed, the parent terminal further enters a determination process for a broadcast signal transmitting terminal. In the situation of FIG. 15, since only one terminal B and terminal D exist in pattern group 1 and pattern group 4, each is selected as a broadcast signal transmitting terminal. In the pattern group 2, although the terminal C exists, the priority is 0, and it cannot be selected as the broadcast signal transmission terminal. Therefore, the terminal C is not selected as the broadcast signal transmission terminal. For pattern group 3, there are two terminals. Here, since M = 1, one terminal is selected. Here, since the priority of terminal F is higher than that of terminal A, terminal F is selected as the broadcast signal transmitting terminal.

  In this example, the position of the terminal is estimated and classified using the antenna pattern. For example, a GPS is installed in the terminal, the position information is notified to the parent terminal, and the parent terminal registers in the database. At this time, the GPS position information may be registered in association with the terminal information. In this case, terminals having close positions may be grouped as one group, and a notification signal notification terminal may be selected from the group.

  Here, how the terminal obtains the received signal when the parent terminal transmits the notification signal in FIG. 3 in a frequency band different from that of the notification signal transmitting terminal will be described using equations.

のように表せる。また、報知信号送信端末の報知信号のベースバンド信号をB(t)、報知信号送信端末の報知信号の搬送波周波数のうち低い方をf3、高い方をf4とする。ここで、Δf = f4-f3であるものとする。この時、報知信号送信端末が送信する報知信号は

となる。 The baseband signal of the notification signal of the parent terminal is A (t), the lower one of the carrier frequencies of the notification signal of the parent terminal is f1, and the higher one is f2. Here, it is assumed that Δf = f2−f1. Then, the notification signal transmitted by the parent terminal is

It can be expressed as Also, let B (t) be the baseband signal of the broadcast signal of the broadcast signal transmission terminal, f3 be the lower carrier frequency of the broadcast signal of the broadcast signal transmission terminal, and f4 be the higher one. Here, it is assumed that Δf = f4-f3. At this time, the notification signal transmitted by the notification signal transmitting terminal is

It becomes.

、報知信号送信端末から子端末までのf3,f4における伝搬路を

とすると受信信号r(t) は以下のように表せる

これに対して受信処理を行い、LPF(1MHz)で高周波成分を取り除くと、

となる。＊は複素共役を表す。親端末の報知信号のベースバンド信号であるA(t)と報知信号送信端末の報知信号のベースバンド信号であるB(t)が同一信号であれば、受信側で特殊な処理をすることなく、また、送信周波数f1, f2, f3, f4によらず、２パスの最大比合成による受信が可能となる。 Assume that Δf is sufficiently small and that the propagation paths in f1 and f2 are sufficiently correlated and can be considered identical. Similarly, assume that f3 and f4 have the same propagation path characteristics. The propagation path in f1 and f2 from the parent terminal to the child terminal that receives the broadcast signal

, The propagation path in f3, f4 from the broadcast signal transmitting terminal to the child terminal

Then, the received signal r (t) can be expressed as

On the other hand, when receiving processing and removing high frequency components with LPF (1MHz),

It becomes. * Represents a complex conjugate. If A (t), which is the baseband signal of the broadcast signal of the parent terminal, and B (t), which is the baseband signal of the broadcast signal of the broadcast signal transmitting terminal, are the same signal, there is no special processing on the receiving side. In addition, reception by the maximum ratio combining of two paths is possible regardless of the transmission frequencies f1, f2, f3, f4.

  Next, description will be made using a specific example. FIG. 22 shows the positions of the parent terminal, the child terminal, and the notification signal transmitting terminal. The distance from the parent terminal to the child terminal is 30 m, and the distance from the notification signal transmitting terminal to the child terminal is 5 m. The parent terminal and the broadcast signal transmitting terminal transmit the broadcast signal as a signal having a bandwidth of 1 MHz with power of −40 dBm / MHz. The parent terminal transmits a beacon signal with a power of -40 dBm / MHz as a signal having a bandwidth of 50 MHz. Since the slave terminal does not know which frequency band the broadcast signal is transmitted to, the slave terminal collectively receives the 1000 MHz bandwidth using a 1000 MHz filter, and performs a 1 MHz broadcast signal reception process. After receiving the notification signal, the beacon signal from the parent terminal is subjected to signal reception processing using a 50 MHz band filter. The broadcast signal is spread to gain. The information is 20 Symbols (the number of bits of 1 Symbol depends on the modulation method). If this information can be received, the child terminal can make a network participation request to the parent terminal and can be told the location of the beacon. The frequency band is assumed to use the 6 GHz band, assuming free propagation loss and no multipath and transmission path changes.

  Since the slave terminal does not know the frequency at which the broadcast signal is present, the slave terminal collectively receives a band (1000 MHz) where the broadcast signal is considered to be transmitted. It is greatly affected. In a situation where the broadcast signal transmitting terminal does not transmit a broadcast signal, the received SNR can be calculated as −33.51 dB. From this point, when trying to obtain SNR = 11.21 dB, the spreading factor must be 29600 times in order to obtain a spreading gain of 44.71 dB. This takes 592 ms to transmit a 20 Symbol signal. However, since the broadcast signal transmitting terminal at a distance of 5 m from the terminal transmits the broadcast signal simultaneously with the parent terminal, the received SNR becomes -17.82 dB, and the spreading gain only needs to be 29.03 dB. .21dB can be obtained. This means that 16 msec is sufficient to transmit a 20 Symbol signal. For this reason, the time required for the slave terminal to complete receiving the synchronization signal can be shortened to 1/37.

  In this state, when the child terminal receives a beacon signal transmitted from the parent terminal, the child terminal can know the frequency band of the beacon signal, so a 50 MHz filter that matches the bandwidth of the beacon signal is used. Can be used. For this reason, even if the parent terminal transmits at -40 dBm / MHz, which is the same as the broadcast signal, the reception SNR of the child terminal is -3.51 dB, and it is possible to perform sufficient communication by obtaining a spreading gain of several dB. Become.

  Thus, the present proposal is an effective means when the size of the area that can receive the notification signal and the size of the area that can receive other data signals are greatly different. For example, even if the terminal is outside the area where the notification signal of the parent terminal can be received, the notification signal can be reliably received from the notification signal transmitting terminal.

  According to the embodiment described above, even when the parent terminal cannot receive the notification signal from the parent terminal during the reception operation, the notification signal from the notification signal transmission terminal is used to request the participation in the network. It becomes easy for the terminal to have to participate in the network.

  In addition, since broadcast signals are transmitted from a plurality of terminals using different frequencies, it is easy for a terminal having a request to participate in the network to participate in the network due to the antenna diversity effect and the frequency diversity effect. Become. Since it becomes easy for a terminal having a request to participate in the network to participate in the network, unintentional parent terminals can be prevented from standing up and the system throughput of the network can be improved.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The figure which shows an example of the system configuration | structure of this embodiment. The conceptual diagram of the alerting | reporting signal and beacon which are transmitted from a parent terminal. The figure which shows an example of an alerting | reporting signal. The figure which shows the relationship between the alerting signal which a parent terminal transmits, and the alerting signal which an alerting signal transmission terminal transmits. The figure which shows the relationship between the alerting signal which a parent terminal transmits, and the alerting signal which an alerting signal transmission terminal transmits. The sequence diagram of a notification signal transmission terminal determination at the time of a child terminal joining a network. The sequence diagram in the case of regularly selecting a notification signal transmission terminal from a child terminal. The block diagram of the radio | wireless communication apparatus of this embodiment. The block diagram of the alerting signal reception process part of FIG. The figure which shows an example of the content of the database which a parent terminal has. The flowchart for updating the value of a database and determining a notification signal transmission terminal. The figure which shows an example of terminal arrangement | positioning. The figure which shows an example of the content of the database which a parent terminal has. The block diagram of the radio | wireless communication apparatus different from FIG. 8 of this embodiment. The figure which shows an example of the content of the database which the parent terminal of the structure of FIG. 14 has. 15 is a flowchart for reception power update, grouping, and broadcast signal transmission terminal selection by the parent terminal of FIG. The figure which shows an example of terminal arrangement | positioning. The figure which shows an example of an antenna pattern. The figure which shows an example of an antenna pattern. The figure which shows an example of an antenna pattern. The figure which shows an example of an antenna pattern. The figure which shows an example of a parent terminal, a child terminal, and an alerting signal transmission terminal.

Explanation of symbols

101, 610, 710 ... parent terminal, 102, 103, 104, 107, 611, 612, 711, 712 ... child terminal, 108 ... broadcast signal transmission instruction information, 201, 401, 405, 406, 501, 505 ... broadcast signal 202, 402, 502 ... beacon, 203 ... data communication, 301 ... narrowband signal, 403, 404, 503, 504 ... data communication signal, 407 ... interference signal, 603 ... measurement packet, 801 ... RF / IF processor 802 ... ADC, 803 ... power measurement processing unit, 804 ... notification signal reception processing unit, 805 ... data signal reception processing unit, 806 ... control processing unit, 807 ... RF / IF processing unit, 808 ... DAC, 809 ... notification signal Transmission processing unit, 810... Data signal transmission processing unit, 811, 1403 ... terminal category database, 812 ... antenna, 90 ... complex multiplication processing section, 902 ... complex conjugate processor, 903 ... complex multipliers, 905 ... matched filter 1401 ... antenna directivity processing unit, 1402 ... control unit, 1404 ... antenna directivity processing unit.

Claims (10)

The first wireless communication device transmits a beacon and a first notification signal including frequency information of the beacon,
A communication method in which a second wireless communication device transmits a second notification signal including frequency information of the beacon at a frequency different from that of the first notification signal.   The communication method according to claim 1, wherein the first wireless communication device notifies the second wireless communication device of instruction information so as to transmit the second notification signal.   2. The communication method according to claim 1, wherein each of the first and second notification signals includes a first signal and a second signal transmitted at a frequency that is a Δf frequency away from the first signal. .   4. The communication method according to claim 3, wherein each of the first notification signal and the second notification signal is transmitted by placing information on a phase difference between the first signal and the second signal.   The communication method according to claim 1, wherein the second wireless communication device notifies the first wireless communication device of a priority according to a time during which power can be continuously supplied.   2. The communication method according to claim 1, wherein there are a plurality of the second wireless communication devices, and each transmits the second notification signal in a time division manner.   The communication method according to claim 1, wherein the second wireless communication device transmits the second notification signal toward the first wireless communication device. The first wireless communication device transmits a beacon and a first notification signal including frequency information of the beacon,
A communication method in which a second wireless communication device transmits a second notification signal including frequency information of the beacon at the same frequency as the first notification signal. First transmission means for transmitting a beacon;
Second transmitting means for transmitting a first notification signal including frequency information of the beacon;
A first wireless communication device including:
A wireless communication system comprising: a second wireless communication device including: a third transmission unit configured to transmit a second broadcast signal including frequency information of the beacon at a frequency different from that of the first broadcast signal. Communication means for communicating with a first wireless communication device for transmitting a beacon and a first notification signal including frequency information of the beacon;
Transmitting means for transmitting a second notification signal including frequency information of the beacon at a frequency different from that of the first notification signal;
A wireless communication device comprising:

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