JP2007104621A - Communication equipment and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To be synchronized with many terminals relating to communication equipment and method for performing communication with a prescribed reference timing as a reference. <P>SOLUTION: A histogram generator 160 is provided as constituted of counter groups for a number corresponding to the detection accuracy of a phase difference, the count value of a counter corresponding to the phase difference between the slot timing of reception signals and the slot timing of a present terminal is updated with a value corresponding to reception signal strength, and a phase difference distribution (histogram) is generated. A weighting window processor 162 detects the spread of the distribution on the basis of a set observation window; a phase correction amount calculator 164 outputs the phase difference for minimizing the spread of the distribution as a correction amount; and a slot timing generator 166 generates the slot timing by frequency-dividing a reference clock by a counter, and executes phase correction by presetting the phase correction amount to a frequency dividing counter at a phase correction timing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a communication apparatus and method, and more particularly to a communication apparatus and method for performing communication based on a predetermined reference timing.

  In general, in a TDMA system, a mobile terminal uses a signal from a reference station (base station) to synchronize slot timing and the like, and therefore cannot synchronize if it cannot receive a signal from the reference station. When synchronization cannot be established, the observed peripheral terminal signals are either uniformly delayed or advanced with respect to their own timing.

Similar synchronization problems occur when considering an autonomous distributed wireless network. In an autonomous decentralized network, a signal frequently occurs when a signal from a certain terminal is delayed but a signal from a certain terminal is advanced. Furthermore, since each terminal individually controls, the situation changes from moment to moment. This problem is particularly noticeable when networks formed by two different groups of mobile terminals that are out of synchronization with each other join. In this regard, in the invention of Patent Document 1, timing is controlled using an average value of the amount of synchronization deviation.
JP-A-9-46762

  However, in the method of adjusting the timing to the average value of Patent Document 1, in the situation where the delay phase and the advance phase are mixed, the intermediate timing at which neither the delay nor the advance is synchronized is determined as the synchronization timing, and any terminal There are cases where synchronization cannot be achieved.

  The present invention has been made in view of the above-described facts, and an object of the present invention is to provide a communication device capable of synchronizing with more terminals.

  In order to achieve the above object, the invention according to claim 1 is a communication device that communicates based on a predetermined reference timing, and that receives a plurality of signals transmitted from other communication devices based on each reference timing. Receiving means for receiving; detecting means for detecting a reference timing of each of the plurality of received signals; and creating a histogram of a phase difference between the reference timing of each of the detected plurality of signals and the predetermined reference timing. A specifying means for specifying a phase difference with another communication terminal that can communicate with a larger number of other communication terminals by changing the predetermined reference timing based on the generated histogram, and the specified Changing means for changing the predetermined reference timing based on the phase difference.

  That is, the present invention is a communication device that performs communication based on a predetermined reference timing.

  The receiving means of this communication apparatus receives a plurality of signals transmitted from other communication apparatuses based on each reference timing. The detecting means detects a reference timing of each of the plurality of received signals.

  The creating means creates a histogram of phase differences between the reference timing of each of the plurality of detected signals and the predetermined reference timing, and the specifying means calculates the predetermined reference timing based on the created histogram. If the change is made, the phase difference with other communication terminals that can communicate with more other communication terminals (specifically, the phase difference with the reference timing of other communication terminals) is specified.

  The changing unit changes the predetermined reference timing based on the specified phase difference.

  As described above, when communicating based on the predetermined reference timing, the phase difference with other communication terminals that can communicate with more other communication terminals when the predetermined reference timing is changed is specified and specified. Since the predetermined reference timing is changed based on the phase difference, it is possible to synchronize with more terminals.

  Here, the specifying means specifies the most frequent phase difference within at least a predetermined time range including the predetermined reference timing. That is, the specifying means may first specify the most frequent phase difference within a predetermined time range including the predetermined reference timing, and secondly, exceed the predetermined time range, The most frequent phase difference may be specified.

  According to a third aspect of the present invention, in the second aspect of the present invention, the communication is repeatedly performed every predetermined time, the predetermined time range exists within the predetermined time, and the reference timing is within the predetermined time range. A determination unit configured to determine whether or not a predetermined number or more of signals matching the predetermined reference timing have been received, and the generation unit sets an interval of the phase difference of the histogram according to a determination result of the determination unit; To change.

  That is, the determination unit determines whether or not a predetermined number of signals having a reference timing that matches the predetermined reference timing are received within the predetermined time range. If it is determined that a predetermined number or more of signals whose reference timing matches the predetermined reference timing are received within the predetermined time range, there are many other communication devices synchronized with the communication device (a predetermined number or more). It can be determined that it exists. In such a case, it is preferable to adjust the reference timing more finely. On the other hand, if it is not determined that a predetermined number or more of signals whose reference timing matches the predetermined reference timing are received within the predetermined time range, there are few other communication devices synchronized with the communication device (predetermined Less than the number). In such a case, it is not preferable to finely adjust the reference timing in order to establish synchronization as soon as possible.

  Therefore, the creation unit changes the interval of the phase difference of the histogram according to the determination result of the determination unit.

  Therefore, according to the synchronization state with other communication apparatuses, the reference timing can be appropriately adjusted with a fine accuracy when the synchronization is achieved to some extent, and with a rough accuracy when the synchronization is not achieved.

  According to a fourth aspect of the present invention, in the second aspect of the present invention, the communication is repeatedly performed every predetermined time, the predetermined time range exists within the predetermined time, and the predetermined time range is within the predetermined time range. When the reference timing is changed, the information processing apparatus further includes a determination unit that determines whether there is a phase difference between other communication terminals that can communicate with more other communication terminals, and the determination unit is determined to be present by the determination unit. If not, the average of the phase differences is specified as the phase difference, and if it is determined by the determining means that the mode difference is present, the most frequent phase difference is specified.

  That is, the determination unit determines whether or not there is a phase difference between other communication terminals that can communicate with more other communication terminals when the predetermined reference timing is changed within the predetermined time range. When it is determined that the phase difference of other communication terminals that can communicate with more other communication terminals by changing the predetermined reference timing is within the predetermined time range, as described above, There are many (a predetermined number or more) other communication devices that synchronize, and the reference timing can be adjusted more finely. Therefore, if the most frequent phase difference is specified and the reference timing is adjusted, the reference timing can be adjusted more accurately.

  On the other hand, it is determined that it is not determined that there is a phase difference between other communication terminals that can communicate with more other communication terminals when the predetermined reference timing is changed within the predetermined time range. If not, as described above, there are few other communication devices synchronized with the communication device (less than a predetermined number), and it is not preferable to specify the most frequent phase difference.

  Therefore, the specifying means specifies the average of the phase differences as the phase difference if it is not determined by the determining means, and specifies the most frequent phase difference if the determining means determines that it exists. To do.

  Therefore, it is possible to appropriately adjust the reference timing according to the synchronization state with other communication apparatuses.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the reference timing is determined based on any of a plurality of regions obtained by dividing a predetermined time, The communication is repeatedly performed at the predetermined time, and transmission and reception during the communication are performed by occupying any of the plurality of areas, and grasping means for grasping an occupation state of the plurality of areas. Further, the changing means changes the predetermined reference timing according to the grasped occupation state.

  That is, the grasping means grasps the occupation state of the plurality of areas.

  Here, when there are many occupied states in the plurality of areas, by changing the timing, the same area is used in competition between the communication apparatus and another communication apparatus, and communication is disturbed. There is a possibility that. Accordingly, it is not preferable to suddenly change the reference timing in such a state.

  On the other hand, when there are few occupation states of the plurality of areas, changing the timing is unlikely to cause competition between the communication apparatus and another communication apparatus, and the reference timing is increased. Changing it will not have much impact.

  Accordingly, the changing means changes the predetermined reference timing by adjusting a change amount according to the grasped occupation state.

  Therefore, it is possible to appropriately adjust the reference timing according to the occupation states of a plurality of areas obtained by dividing a certain time.

  According to a sixth aspect of the present invention, in the first aspect of the present invention, the detection unit is configured to detect only a signal having a signal level equal to or higher than a predetermined value from the plurality of received signals. Is extracted to detect the reference timing. This is because it is considered that other communication devices that transmit a signal with a signal level less than a predetermined value will generally not synchronize with the communication device in the near future, and there is no need to synchronize with such a communication device. Because. On the other hand, when the signal level is equal to or higher than a predetermined value, the necessity for synchronization increases as the signal level increases.

  Therefore, the creation means of the invention described in claim 7 creates the histogram of the phase difference by weighting according to the signal level.

  Therefore, the reference timing can be adjusted according to the necessity of synchronization.

  Note that the communication method according to the eighth aspect of the present invention has the same operations and effects as the communication apparatus according to the first aspect, and therefore the description thereof is omitted.

  The invention according to claim 9 is a communication device that communicates based on a predetermined reference timing, wherein the receiving unit receives a plurality of signals transmitted from other communication devices based on each reference timing, and the reception Detection means for detecting a reference timing of each of the plurality of signals, creation means for creating a histogram of phase differences between the reference timing of each of the detected plurality of signals and the predetermined reference timing, and the created The histogram is periodically expanded, a calculation area determined in one period is determined by shifting a plurality of areas in the periodically expanded histogram, and the distribution state of the histogram at each position of the determined calculation areas for one period Based on the calculation means for calculating the physical quantity representing the position, the position of the predetermined calculation area, and the physical quantity calculated by the calculation means And a, a changing means for changing the predetermined reference timing.

  The reception means, detection means, and creation means perform the same processing as in the first aspect. Then, the calculation means of the present invention periodically expands the created histogram, determines a calculation area determined in one period while shifting the calculation area by a plurality of times in the periodically expanded histogram, and the plurality of determined calculation areas A physical quantity representing the distribution state of the histogram in each is calculated.

  Then, the changing unit changes the predetermined reference timing based on the position of the calculation area for the determined one period and the physical quantity calculated by the calculating unit.

  Here, the physical quantity representing the distribution state is a physical quantity representing the spread of the histogram, for example, variance, absolute average, mean square, etc., as in claim 10, and the changing means has the spread of the histogram. The predetermined reference timing is changed based on the position of the calculation area that is minimized.

  In this way, the generated histogram is periodically extended, and a calculation area determined in one period is determined by shifting the calculation area by a plurality of times in the periodically expanded histogram, and the histograms in each of the determined calculation areas are determined. Since the physical quantity representing the distribution state is calculated and the predetermined reference timing is changed based on the position of the predetermined calculation area for one period and the physical quantity calculated by the calculation means, the predetermined reference timing Changes can be made in a short time.

  Note that the communication method according to the eleventh aspect of the present invention has the same operations and effects as the communication device according to the ninth aspect, and therefore description thereof is omitted.

By the way, the detection means of the invention described in claim 6 extracts only a signal having a signal level equal to or higher than a predetermined value from the plurality of received signals, and the creation means of the invention of claim 7 sets the signal level to the signal level. The histogram of the phase difference is created by weighting in accordance with the phase difference. In the invention according to claim 12, the creating means weights each of a plurality of received signals according to a signal level to calculate the phase difference. Create a histogram.

  According to a thirteenth aspect of the present invention, there is provided a communication device that communicates with reference to a predetermined reference timing, the receiving means for receiving a plurality of signals transmitted from other communication devices based on each reference timing, and the reception Detecting means for detecting a reference timing of each of the plurality of received signals; weighting each of the plurality of received signals according to a signal level; and a reference timing of each of the detected plurality of signals and the predetermined reference Creating means for creating a histogram of phase differences with respect to timing; a physical quantity representing a distribution state of the histogram at each position of the plurality of calculated areas determined by shifting a plurality of predetermined calculation areas in the generated histogram; Based on the position of the determined calculation area and the physical quantity calculated by the calculation means Includes a changing means for changing the reference timing, the.

  That is, the receiving means of the present invention receives a plurality of signals transmitted from other communication devices based on each reference timing, and the detecting means detects the reference timing of each of the received signals.

  The creating means weights each of the plurality of received signals according to a signal level, creates a histogram of phase differences between the reference timing of each of the detected plurality of signals and the predetermined reference timing, and calculates The means determines a predetermined calculation area by shifting a plurality of predetermined calculation areas in the generated histogram, and calculates a physical quantity representing the distribution state of the histogram at the position of each of the determined calculation areas.

  The changing unit changes the predetermined reference timing based on the position of the determined calculation area and the physical quantity calculated by the calculation unit.

  In this way, a histogram is created by weighting each of the plurality of signals according to the signal level, and the reference timing is changed based on the histogram. Therefore, the reference timing can be adjusted according to the necessity of synchronization. .

  As described above, the physical quantity representing the distribution state is a physical quantity representing the spread of the histogram, and the changing unit is configured to perform the predetermined reference timing based on the position of the calculation area where the spread of the histogram is minimized. To change.

  Specifically, as in claim 15, the creating means includes count value storage means for storing a count value for each of a plurality of phase differences, and each of the plurality of received signals is set to the signal level. The histogram is created by updating the count value of the counter value storage means corresponding to the phase difference of each signal with the value obtained by weighting accordingly.

  In this case, as in claim 16, each time the predetermined reference timing is changed, the counter further comprises count value reset means for resetting the count value stored in each count value storage means of the creation means. As shown in FIG. 17, each time the predetermined reference timing is changed, the count value reducing means for reducing the count value stored in each count value storage means of the creating means, and every time the predetermined reference timing is changed. The phase difference corresponding to the count value storage means that became the reference when the predetermined reference timing was changed last time is zero, the specifying means for specifying the phase difference value corresponding to each count value storage means, May be further provided.

  As described above, the present invention specifies the phase difference of other communication terminals that can communicate with more other communication terminals when the predetermined reference timing is changed when communicating based on the predetermined reference timing. Since the predetermined reference timing is changed based on the specified phase difference, it is possible to synchronize with more terminals.

  In addition, the present invention periodically expands the created histogram, and calculates a physical quantity representing the distribution state of the histogram in each of the defined calculation areas for one period with respect to the periodically expanded histogram. Since the predetermined reference timing is changed based on the position of the determined calculation area and the physical quantity calculated by the calculation means, the reference timing can be changed without obtaining an average value of timing deviation amounts. And can be performed in a short time.

  Furthermore, the present invention creates a histogram by weighting each of the plurality of signals according to the signal level, and changes the reference timing based on the histogram. Therefore, the reference timing is adjusted according to the necessity of synchronization. Can do.

  Hereinafter, a communication device according to a first embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the communication apparatus according to the present embodiment includes an antenna 12, a transmission / reception unit 14, a demodulation unit 16, a modulation unit 18, a communication control unit 20, and the like as reception means. The communication apparatus according to the present embodiment performs communication based on a predetermined reference timing adjusted by controlling the phase of the clock.

  The communication control unit 20 is connected to the reception control unit 20 and the reception control unit 20 connected to the demodulation unit 16, and is received by the antenna 12, and receives a plurality of signals (other signals) from other communication devices based on the respective reference timings. A reference signal generated by the reference signal generation unit 24, a reference signal generation unit 24, and a clock correction unit 32, which will be described later, as detection means for detecting a reception timing of the packet) and generating a reference signal for slot synchronization A phase difference detection unit 26 that detects a phase difference from the output clock at each slot timing, a histogram is generated from phase difference information for a predetermined time detected by the phase difference detection unit 26, and a mode value (others) In this embodiment, the clock generation unit 30 generates a feature according to the feature quantity extracted by the feature extraction unit 28 and the feature extraction unit 28 that detects the average value and the like as the mode value. Clock correction section 32 as changing means for adjusting the timing to control the clock phase, and, a transmission control unit 34 connected to the modulator 18. The phase difference detection unit 26 and the feature extraction unit 28 constitute a creation unit and a specification unit.

  Next, the operation of the present embodiment will be described.

  This communication apparatus establishes communication with other communication apparatuses and communicates. That is, between communication devices, one communication device occupies one of a plurality of slots divided into one frame, and another communication device occupies one of the other slots, based on each slot time. The transmission / reception is performed according to the reference timing adjusted as described later.

  For example, when a signal is transmitted from the communication device to another communication device, the signal is transmitted from the antenna 12 via the modulation unit 18 and the transmission / reception unit 14 in accordance with the clock timing (reference timing) adjusted by the clock correction unit 32. Send.

  On the other hand, when a signal from another communication device is received by the antenna 12, the signal is transferred to the reception control unit 22 via the transmission / reception unit 14 and the demodulation unit 16, and further transferred to another signal processing unit (not shown). Is done.

  Thus, in order to communicate with other communication apparatuses, it is important to adjust the reference timing as described above.

  Here, with reference to FIG. 2 and FIG. 3, a problem when the timing is adjusted to the average value of the conventional invention will be described.

  When a mobile body (including a communication device) moves in a group like an automobile, network merging frequently occurs. The example of FIG. 2 shows a scene where the vehicle X is newly joined to the network of the vehicle group A and the network consisting of the vehicle group B. At this time, it is considered that each network (within the vehicle group) is synchronized to some extent, but it is generally not synchronized between networks (between the vehicle groups).

  FIG. 3 shows how the slot timing is shifted when such network merging occurs. The A group and the B group shown in FIG. 3A are synchronized to some extent and have the same phase, but they are observed as being mixed at the boundary (A + B) between the A group and the B group. As a result, as shown in FIG. 3B, the phase distribution is observed in the vehicle X existing at the boundary between the A group and the B group in a form in which both the leading phase and the lagging phase are mixed. In such a situation, when the conventional averaging control is performed, the terminal X determines that the middle of both groups is the correct synchronization timing, and the timing is shifted in both groups. Absent.

  Therefore, in this embodiment, in order to avoid this problem and to synchronize with more terminals, the reference timing is adjusted as follows.

  First, the communication control process of this embodiment will be outlined.

  When a packet signal is received from another communication device by the antenna 12, the packet signal is transferred to the reception control unit 22 via the transmission / reception unit 14 and the demodulation unit 16, and the reference signal generation unit 24 receives the packet reception timing. Is detected, and a reference signal for slot synchronization is generated.

  The phase difference detection unit 26 detects the phase difference between the reference signal generated by the reference signal generation unit 24 and the clock output from the clock correction unit 32 at each slot timing.

  The feature extraction unit 28 generates a histogram from the phase difference information for a predetermined time detected by the phase difference detection unit 26, and detects a mode value, a maximum value, an average value, and the like.

  The clock correction unit 32 adjusts the timing by controlling the phase of the clock generated by the clock generation unit according to the feature amount extracted by the feature extraction unit 28.

Next, the communication control process of this embodiment will be described in detail.
When the phase difference is input from the phase difference detection unit 26 for a predetermined time, the feature extraction unit 28 starts the feature extraction processing program shown in FIG. 4, and in step 42, the number of sections S of the histogram is set to an initial value S 1, for example, 8. In step 44, a histogram is created as shown in FIG. The histogram divides the slot time T of each of a plurality of slots obtained by dividing one frame by the number of sections S, and each phase difference input within the predetermined time corresponds to a phase difference corresponding to any section. It is created by plotting the number corresponding to each phase difference.

  In step 46, the phase difference having the maximum number, that is, the mode value of the phase difference is output to the clock correction unit 32 based on the created histogram. In this way, the clock correction unit 32 that has input the most frequent phase difference cancels the phase difference based on this phase difference, that is, its own reference timing is changed to the phase difference corresponding to the most frequent value. The clock is adjusted so that the corresponding reference timing is obtained. Note that this clock adjustment may be completed in one process or may be gradually adjusted.

  In the next step 48, it is determined whether or not there are a predetermined number or more of terminals having the same timing. That is, it is determined whether a predetermined number or more of signals whose reference timing matches the reference timing of the communication apparatus have been received. If it is determined that a predetermined number or more have been received, it can be determined that there are many (a predetermined number or more) other communication devices that are synchronized with the communication device. In such a case, the reference timing is more detailed. Adjust. Therefore, the number of sections in the histogram is set more finely. That is, in step 50, it is determined whether or not the number of sections S of the histogram is S1, and if it is determined that it is S1, in step 52, the number of sections S is set to S2 (> S1), for example, 16 Etc. In the next step 58, it is determined whether or not one frame has elapsed. If it is determined that one frame time has elapsed, the process returns to step 44 to create a histogram. As described above, when a histogram is created by setting the number of sections S of the histogram to S2, for example, 16, for example, as shown in FIG. 5B, the number of sections of the phase difference is set to 16 and a histogram is created. The

  On the other hand, if it is not determined in step 48 that there are more than a predetermined number of terminals having the same timing, it is determined in step 54 whether or not the number of sections S of the histogram is set to S2, and the number of sections S is If it is set to S2, the number of sections S is set to S1 in step 56.

  In this way, when communicating based on the predetermined reference timing, the phase difference that can be communicated with more other communication terminals when the predetermined reference timing is changed is specified, and the predetermined phase difference is determined based on the specified phase difference. Since the reference timing is changed, it is possible to synchronize with more terminals.

  In the present embodiment, the case of joining the network of vehicle groups has been described as an example, but the present invention is not limited to this. For example, two vehicle groups or 30 vehicle groups are used. If the number of vehicle groups is extremely different, that is, if the number of moving body groups constituting the plurality of moving body groups is less than the number of other moving body groups by a predetermined number or more, the number of vehicle groups is small. You may make it synchronize with a vehicle group.

  Next, a second embodiment of the present invention will be described.

  Since the configuration of this embodiment is the same as that of the first embodiment, description thereof is omitted.

  Next, the operation of the present embodiment will be described. Since the operation of the present embodiment is similar to that of the first embodiment, different portions will be described below.

  By the way, when performing communication control in a time slot divided into slots, each slot is not always occupied. As shown in FIG. 6, there are cases where many slots are occupied (middle stage), while there are cases where there are many empty slots (lower stage). If the slot occupancy is high, a slight synchronization may affect other terminals, but if the slot occupancy is low and there are many empty slots, a slight synchronization shift may be allowed. Many. Therefore, in this embodiment, the reference timing is changed by adjusting the change amount of the reference timing in accordance with the slot occupancy.

  That is, when the mode value of the phase difference is input from the feature extraction unit 28, the clock correction unit 32 starts the reference timing change processing program shown in FIG. 7 and sets a variable C for counting the number of elapsed frames in step 60. In step 62, the slot occupancy is grasped. In step 64, it is determined whether the slot occupancy is high. If this occupancy is high, changing the reference timing will likely cause contention for the same slot between this communication device and other communication devices, thereby interfering with each other's communication. . It is not preferable to greatly change the reference timing in such a state. Therefore, the reference timing change amount m is set to a relatively small amount m1 (<m2). Furthermore, since a large amount of phase difference information can be obtained within a predetermined time in a state where the occupation ratio is high, the period Q of the change in the reference timing is set to a relatively small value q1 (<q2) in step 68.

  On the other hand, if it is determined that the slot occupancy is not high, even if the reference timing is changed, it is unlikely that the same slot competes with the other slot. For this reason, even if the reference timing is largely changed, the influence is not great. Therefore, in step 70, the reference timing variation m is set to a relatively large value m2 (> m1). Further, in a state where the occupation ratio is low, there is little information on the phase difference obtained within a predetermined time, and therefore, in step 72, the reference timing change period Q is set to a relatively large value q2 (> q1). For example, q1 can be 1 and q2 can be 3.

  In step 76, the clock timing is changed by the change amount m. Thereafter, after the waiting time Q has elapsed, the process returns to step 62 and the above processing is repeated.

  As described above, when the slot occupancy is high, the change amount of the reference timing is relatively small and the change period is also changed in a short period. When the slot occupancy is not high, the change amount of the reference timing is changed. Is changed relatively large, and the reference timing is changed with the reference timing change period being a relatively large period. Thus, in the present embodiment, the reference timing can be adjusted appropriately according to the slot occupancy.

  Next, a third embodiment of the present invention will be described. Since this embodiment has the same configuration as that of the first embodiment described above, description thereof is omitted.

  Next, the operation of the present embodiment will be described. Since the operation of this embodiment is similar to that of the first embodiment described above, different portions will be mainly described.

  The feature extraction unit 28 executes a feature extraction processing program shown in FIG. In step 92, a phase difference histogram is created. In step 94, it is determined whether or not there is a timing that can be synchronized with more terminals in the vicinity (within a predetermined time) of the reference timing of the communication apparatus. If the reference timing is changed, it is determined whether or not more synchronization can be achieved than the current timing, and if it is determined that synchronization can be established with more terminals, in step 98, as in the first embodiment described above. In addition, the mode value of the phase difference is extracted and output to the clock correction unit 32.

  On the other hand, if a negative determination is made in step 94 or step 96, an average value is extracted in step 100.

  The processing of this feature extraction processing program will be described in more detail with reference to FIGS. FIG. 9 shows a case where the reference timing of the communication apparatus is a minority. That is, the reference timing of this communication apparatus and the case where there are no or few other communication terminals synchronized are shown. For example, as shown in FIG. 9A, when there are few other communication terminals with a reference timing that matches the reference timing of this communication apparatus and there are relatively many communication terminals with a nearby phase difference, Synchronize the synchronization timing. On the other hand, if there is no peak in the vicinity, the average value is specified. Thereafter, for example, as shown in FIG. 9C, when synchronization with more terminals in the vicinity can be established, the reference timing is adjusted to that timing. Thereby, the reference timing is adjusted as shown in FIG.

  FIG. 10 shows processing when the reference timing of this communication terminal is majority, that is, when there are a predetermined number or more of other communication terminals synchronized with the reference timing. In the case shown in FIG. 10A, since the reference timing of the communication terminal is a peak, in this case, an average value is specified. In the case shown in FIG. 10B, since the timing of itself is a peak, the average value is specified also in this case. After that, as shown in FIG. 10C, when the own timing becomes larger than the timing in the vicinity, the control is also performed based on the average value in this case. Thereby, the reference timing is adjusted as shown in FIG.

  Next, a fourth embodiment of the present invention will be described. Since the configuration of this embodiment is the same as that of the first embodiment described above, description thereof is omitted.

  Next, the operation of the present embodiment will be described. Since the operation of the present embodiment is similar to the operation of the first embodiment described above, different portions will be mainly described.

  The reference signal generation unit 24 in the first to third embodiments described above extracts the reference signal from all received signals, and the feature extraction unit 28 is as shown in FIG. A constant histogram is created. However, there are signals to be received whose signal level is large or small. A device with a high reception level is close to the communication terminal and needs to be synchronized. On the other hand, when the reception level is low, it does not exist near the communication terminal and gradually from the network of the communication terminal. It can be determined that they are not. Therefore, it is not preferable to adjust its own reference timing in consideration of the reference timing of all communication terminals including communication terminals existing in the vicinity of this communication terminal and communication terminals that deviate from the network of this communication terminal. It is more preferable to adjust the reference timing with the communication terminal existing in the vicinity of the communication terminal. Therefore, as shown in FIG. 11B, the reference signal generation unit 24 first extracts only those whose reception level (reception power) is equal to or greater than a certain value (predetermined power). As a result of such processing, as shown in FIG. 11 (a), the histogram created based on all the received signals is limited to those whose reception level is a certain value or more, as shown in FIG. 11 (b). 11 (a), the most frequent phase difference is Δ1, but in FIG. 11 (b), for example, the one having the phase difference of Δ2 is the most frequent. There is a case. Further, as described above, when the signal level is larger, the reference timing should be adjusted more, while those having a low reception level are relatively less necessary. Therefore, weighting is performed according to the reception level, and a histogram is created as shown in FIG. Accordingly, Δ3 whose number is not so large in FIGS. 11A and 11B can be determined as the most frequent phase difference as a result of weighting in FIG. 11C. Therefore, in this embodiment, the reference timing can be adjusted as necessary for synchronization.

  In addition, only those whose reception level is a certain value or more are extracted and weighted according to the reception level of the extracted signal, but depending on the reception level of each signal including signals whose reception level is less than a certain value You may make it weight.

  Next, a fifth embodiment of the present invention will be described. Since the configuration of the present embodiment is substantially the same as that of the first embodiment, the same parts are denoted by the same reference numerals, description thereof is omitted, and only different parts are described.

  In this embodiment, instead of the phase difference detection unit 26 and the feature extraction unit 28 in the first embodiment, a histogram of the phase difference obtained in the phase difference detection unit 26 is generated, and a plurality of histograms are generated. Adjacent, that is, in the present embodiment, the histogram (cycle extension) generation unit 110 serving as a creation unit that extends the same histogram by one cycle, and the cycle expanded histogram for one cycle Apply the observation window to obtain the spread of the distribution within the observation window (dispersion, absolute average, mean square, etc.), and repeat this operation while scanning the observation window for one slot time. A window processing unit 120 that determines a timing corresponding to the position of the window as a synchronization timing. Note that the clock correction unit 32 adjusts the timing based on the synchronization timing determined by the window processing unit 120.

  By the way, when the amount of timing deviation between the own reference signal and the observed signal is detected as described above and the synchronization control is performed using the average value as a target value, the following another problem occurs. That is, FIG. 13A and FIG. 13B show the distribution of the amount of reception timing deviation of its own reference signal and the packet from the peripheral terminal. The distribution of the reception timing of packets from the peripheral terminals is the same, but the timing of the reference signal is different between FIG. 13 (A) and FIG. 13 (B). In FIG. 13A, the average value H1 and the distribution peak P1 substantially coincide with each other, whereas in FIG. 13B, the average value H2 and the distribution peak P2 are shifted.

  As in this example, the above method has a problem that a distribution shift occurs depending on how to obtain a reference signal for detecting a timing shift. This problem becomes a big problem in an autonomous communication system. Since the average value changes due to the shift of the distribution, the target value of the synchronization timing of each terminal varies. For this reason, there is a problem that the time required to establish synchronization becomes very long.

  This will be further described with reference to FIG. FIG. 14 is a diagram showing that the speed until synchronization is established varies depending on how the reference signal is acquired. Example A and Example B are examples in which the same signal is observed, but the reference is changed. In Example A shown in FIG. 14A, the processing is performed assuming that the timing of the observation signal is delayed from the reference signal. Example B shown in FIG. 14B is an example in which the timing of the observation signal is treated as being advanced from the reference signal. In Example A, the reference signal is delayed by the period t1, whereas in Example B, the reference signal is advanced by the period t2 (> t1). As can be understood by comparing these, the processing such as Example A clearly has a small amount of timing shift and is expected to establish synchronization at high speed. Conversely, when processing is performed as in Example B, the amount of timing shift is large and it takes time to establish synchronization.

  The problem of how to take the above-mentioned standard becomes particularly remarkable in synchronization in an autonomous distributed network. As in the example illustrated in FIG. 15, it is assumed that the terminals A and B are already synchronized, and the timings of the reference signals of both are the same. If terminal A detects the amount of delay with respect to the observed signal and terminal B observes the amount of advance, both perform different control at the next moment. The terminal A that observes the delay amount tries to synchronize by delaying its own reference signal, while the terminal B that observes the advance amount tries to synchronize by advancing its own signal. As a result, the terminal A and the terminal B, which should have been synchronized, are out of synchronization.

  Therefore, in this embodiment, in order to solve such a problem, a process (see FIG. 16) is performed in consideration of the periodicity of the timing deviation amount. In a time-division system in which slots are periodically cut, it is necessary to consider the periodicity and treat the half-slot delay and half-slot advance as the same.

  Specifically, first, the histogram generation unit 110 creates a histogram of the amount of timing deviation in step 150, and in step 152, as shown in FIG. 17 and FIG. A histogram is generated by periodically extending the histogram. Thereafter, in step 154, the window processing unit 120 processes the periodically expanded histogram through the observation window W corresponding to one slot time (time between two consecutive reference signals) T (see FIG. 18). Specifically, the spread of the histogram in each one-slot time T is calculated while the window W is shifted little by little, for example, 20% of the one-slot time T. Here, the spread can be obtained from variance, absolute average, square average, and the like.

  In step 156, the calculation result (histogram spread) is stored in a memory (not shown). In step 158, it is determined whether the observation window shift amount is one slot time or more. In the above example, it is determined whether or not it has been shifted five times. If it is determined that the shift amount of the observation window is not longer than one slot time, the observation window position is shifted in step 160 and the process returns to step 154. On the other hand, if the shift amount of the observation window is determined to be one slot time or more, in step 162, the window position where the spread is minimized is determined as the synchronization timing.

  When processed in this way, as shown in FIGS. 19 (A) to 19 (E), the observation window is shifted five times, and the spread of the histogram at each position is as shown in FIGS. 20 and 21, for example. , It is calculated that the spread of the histogram at the position where the observation window is shifted by 0.6 is minimum.

  In the above processing, if the same observation signal can be obtained in each communication terminal, the same timing is determined as the synchronization timing, so that terminals having different reference signal timings are controlled with the same timing as a target. .

  22A to 22C show the conventional method J in which the timing corresponding to the average value of the distribution is set as a target value without considering the periodicity, and the spread of the distribution is most considered in consideration of the periodicity of the distribution. The target value by the method (this embodiment) H which makes the timing which becomes small a target value is shown. As shown in FIG. 22A, when the timing of its own reference clock is almost at the center of the distribution, there is no significant difference between the target values. Conversely, as shown in FIGS. 22B and 22C, when the own clock timing is shifted from the center of the distribution, the target values of the method J and the method H are separated.

  As understood from FIG. 22, the target value changes depending on its own clock timing in the scheme J, whereas the scheme H always operates so as to target the center of the distribution. For this reason, compared with the scheme J, the scheme H can greatly shorten the time until synchronization is established.

  In the fifth embodiment described above, the observation time for creating the histogram in the creation means for creating the phase difference histogram is fixed regardless of the number of signals from the observed peripheral terminals. However, it may be variable according to the number of received signals. The histogram update period may be shortened when there are many signals from the peripheral terminals received, and the histogram update period may be lengthened when there are few signals from the peripheral terminals received.

  Further, by adjusting the shift amount of the observation window in the present embodiment, an effect similar to that of the third aspect can be obtained.

  Furthermore, the clock correction unit 32 according to the present embodiment may perform the same processing as in the second embodiment.

  Next, a sixth embodiment of the present invention will be described in detail.

  As shown in FIG. 23, the communication apparatus according to the present embodiment includes a phase difference detector 152 that detects the slot timing phase of the terminal at the packet reception timing, and a received signal strength detection that detects the received signal strength at the packet reception timing. 156, a histogram generation unit 160 configured with a number of counter groups corresponding to the detection accuracy of the phase difference (step size on the horizontal axis of the phase difference distribution) for generating the phase difference distribution (histogram), and detection A counter selection unit 154 that outputs a counter number of a counter that increases the counter value in accordance with the phase difference, a counter control signal generation unit 158 that generates a counter increase signal according to the detected phase difference and the received signal strength, and a setting Weighting window processing unit 162 that detects the spread of the distribution based on the observed window, and the phase difference that minimizes the spread of the distribution A correction amount is output, and after the correction amount is output, the phase correction amount calculation unit 164 that resets the counter group and the reference clock is divided by the counter to generate the slot timing, and the phase correction amount is divided by the phase correction timing. A slot timing generation unit 166 that performs phase correction by presetting the counter.

  Next, the operation of the present embodiment will be described.

  In general, in an autonomous distributed network, communication slot timings do not always match between all peripheral terminals. In addition, the intensity of signals received from peripheral terminals varies depending on the distance and the shielding situation of the terminals. In such a situation, it is important to preferentially synchronize with a terminal such as a short-distance terminal, where the received signal strength is large and the shift of the slot timing phase causes packet collision and has a large effect on the decrease in throughput. desirable.

  However, in the phase control method disclosed in Patent Document 2, the increment of the histogram generation counter group is fixed to 1 and all received signals are handled equally, so the received signal strength as described above is taken into consideration. The generated phase difference distribution cannot be generated.

  Therefore, in an autonomous decentralized network that does not have a reference station (base station), it is possible to stably establish slot synchronization of the entire system while maintaining synchronization with as many peripheral terminals as possible even in a transient state of synchronization establishment. It is also an object to provide a possible synchronization device. As described above, the present embodiment also has the same purpose as that of the fifth embodiment, but in the fifth embodiment, only a predetermined reception level (reception signal strength) is mainly greater than or equal to a certain value. In contrast to extracting and weighting according to the level to create a histogram, in this embodiment, as will be described in detail later, all received signals are targeted according to the received signal reception level. The difference is that a histogram is created by weighting. Hereinafter, the operation of the present embodiment will be described in detail.

  The histogram generation unit 160 resets the histogram generation counter group (0 to M−1) in response to the reset signal from the phase correction amount calculation unit 164.

  As shown in FIGS. 24A to 24D, the phase difference detection unit 152 latches the frequency division counter output value output from the slot timing generation unit 166 at the packet reception timing, thereby The slot timing phase difference of the peripheral terminal with respect to the slot timing phase is detected, and a phase difference signal is output.

  By the way, as shown in FIG. 24B to FIG. 24D, the frequency division counter output value has its own slot timing in an area that is temporally around this timing with reference to its own slot timing phase. The value corresponds to the phase difference from the phase. Then, when the slot timing of the peripheral terminal and its own slot timing phase match, the phase difference detection unit 152 outputs 0 of the phase difference signal as shown in FIG. If the slot timing phase of the terminal is ahead of its own slot timing phase, as shown in FIG. 24C, a phase difference signal that advances the counter by the phase difference is output, and the slot timing of the peripheral terminal Is delayed from its own slot timing phase, a phase difference signal that delays the counter by the amount of the phase difference is output as shown in FIG.

  As shown in FIG. 25, the counter selection unit 154 determines a counter number (m) to be increased according to the detected phase difference, and outputs this to the counter control signal generation unit 158.

  Here, the counter number corresponding to the phase difference is determined by searching for a value of m that satisfies the following equation.

  Here, N is a frequency division counter output value output from the slot timing generation unit 166 (the number within a predetermined period is, for example, 1020), and M is the number of counters in the histogram generation unit 160 (for example, FIG. 25). As shown in FIG. For example, if M = 17 and N = 1020, m = 11.

  The configuration of the reception signal strength detection unit 156 will be described. As shown in FIG. 26A, the reception signal strength detection unit 156 includes a memory 156A that stores a table indicating the relationship between the threshold value and the increment of the counter, and a counter. Counter enable signal generator 156B that generates an enable signal (see also FIG. 26B) having a length of time (the number of clocks) corresponding to the increment of the above, and the enable signal to the counter selected by the counter selector 154 And a selection output device 156C for selective output.

  The reception signal strength detection unit 156 configured as described above first detects the signal strength of the packet signal at the packet reception timing. Next, based on the relationship between the threshold value stored in the table and the increment of the counter, the increment of the counter is determined from the threshold corresponding to the signal intensity detected this time.

  As shown in FIG. 26B, the counter enable signal generator 156B generates an enable signal having a time length (number of clocks) corresponding to the increment of the counter, and the generated enable signal is generated by the counter selection unit 154. The selected counter 156C selectively outputs the selected counter.

  As shown in FIG. 27, the histogram generation unit 160 increments the counter to which the enable signal is input to generate a histogram.

  Further, as shown in FIG. 28, the histogram generation unit 160 sends the counter value of each counter to the FIR filter 162A in which the weighting window is set in the weighting window processing unit 162 when it is time to correct the slot timing. Load it. The FIR filter 162A passes the counter values (seven in FIG. 28) in the weighting window to the adder 162B. The adder 162B weights each counter value of the counter in the weighting window using a weighting coefficient determined according to the position in the weighting window. In FIG. 28, a weighting coefficient that increases as the distance from the center of the weighting window increases. The adder 162B adds the counter values of the counters in the weighting window thus weighted, thereby adding a feature amount of the phase difference distribution (a physical quantity representing the spread of the distribution, for example, variance (other, absolute Average, square average, etc.) are extracted. The above is repeated for one round while the FIR filter 162A cyclically shifts the data.

  The weighting factor and the weighting window are set from the phase correction amount calculation unit 164. Further, the weighting window process may be realized by software.

  Then, the memory 162C holds the weighted addition value when the center of the weighting window is set to the position of each counter.

  The phase correction amount calculation unit 164 determines the phase correction amount as follows. That is, first, based on the feature value of the phase difference distribution output from the weighting window processing unit 162, the center of the weighting window (counter number K (K = 0 to M-1) is determined as the target value of the slot timing phase, and the phase correction amount is calculated by substituting this counter number K into the following equation.

  The slot timing generator 166 executes phase correction by presetting the value of the frequency division counter based on the phase correction amount calculated by the phase correction amount calculator 164.

  Thus, as shown in FIG. 29 (A), the phase correction is executed by presetting the value of the frequency division counter based on the phase correction amount, and when the next correction timing is reached, As shown in B), the histogram generation unit 160 resets the histogram generation counter group (0 to M−1) in response to the reset signal from the phase correction amount calculation unit 164. Then, as described above, the phase correction is performed and the above is repeated, so that the optimum timing can be obtained as shown in FIG.

  As described above, in the present embodiment, since the increment of the histogram is made variable so that the slot timing phase of a packet with a large received signal strength is emphasized according to the received signal strength, a short-distance terminal As shown, the received signal strength is large, and the slot timing phase between terminals, in which the shift of the slot timing phase greatly affects the decrease in throughput, is preferentially matched, and the decrease in throughput due to packet collision is reduced.

  Further, in the present embodiment, by selecting the center of the weighting window that minimizes the value obtained by cyclically performing the weighting window processing on the generated slot timing phase difference distribution as a target value of the slot timing phase, Each terminal is controlled to have a common slot timing phase even if the slot timing reference is different. As a result, slot synchronization of the entire network can be established in a short time.

  Next, a modification of the sixth embodiment will be described. Since this modification includes the same components as those of the sixth embodiment described above, the same portions are denoted by the same reference numerals, the description thereof is saved, and different portions are described.

  That is, as shown in FIG. 30, the communication apparatus according to the present modification adds an offset value for adding an offset value for changing the correspondence between the horizontal axis of the phase difference distribution (divided phase difference range) and the counter group. And a data cyclic shift unit 161 that cyclically shifts the data so that the position of the phase difference zero becomes the center of the phase difference distribution.

  Next, the operation of the present modification will be described. Since the operation of the present modification is substantially the same as the operation of the sixth embodiment described above, only the different parts will be described below.

  In the above-described sixth embodiment, the count value of the counter of the histogram generation unit 160 is reset every time the own slot timing phase is corrected. However, in the present embodiment, such a complete reset is not performed and the influence of the past state is taken into account to some extent. Therefore, the phase correction amount calculation unit 164 adds the phase correction in addition to the processing in the sixth embodiment. At the timing, the value of the counter group of the histogram generator 160 is multiplied by λ (forgetting factor; 0 ≦ λ ≦ 1) (preset). If λ = 0, the result is the same as in the above-described embodiment.

  In this way, in this modification, since the complete reset is not performed and the influence of the past state is taken into account to some extent, the counter at the center of the counter of the histogram generation unit 160 is the same as in the above-described embodiment. When the above processing is executed assuming that the counter has a phase difference of 0, for example, the phase difference of the counter K instead of the central counter corrects the phase of its own slot timing as shown in FIG. 31A from the past state. When the correction is performed as the previous one, the position of the phase difference 0 should be the counter K at the next correction timing, but the counter value is incremented with the central counter as the position of the phase difference 0. Therefore, the correct distribution cannot be obtained.

Therefore, in this modification, every time the phase of its own slot timing is corrected, the offset adding unit 157 changes the correspondence between the horizontal axis (divided phase difference range) of the phase difference distribution and the counter group. with adding the offset value M _ofst (n), the data cyclic shift section 161 cyclically shifts the data so that the position of the phase difference zero is the center of the phase difference distribution. Since the offset value M _ofst (n) can be grasped every time the phase correction amount calculation unit 164 corrects the phase correction amount calculation unit 164, the offset addition unit 157 and the data cyclic shift unit 161 _{Specify the} shift amount M _ofst (n). The shift direction shifts to the left (in the direction of smaller numbers) when M _ofst (n)> 0, and shifts to the right (in the direction of larger numbers) when M _ofst (n) <0. is there.

  As described above, in this modification, in addition to the effects of the sixth embodiment described above, the correspondence between the phase difference distribution and the counter is changed, and the distribution is continuously updated while the phase difference distribution is maintained. By doing so, there is a further effect that stable synchronization timing control can be realized even in a situation where the number of peripheral terminals is small.

  In addition, in the present modification, the value of the counter group of the histogram generation unit is collectively set to λ times (0 ≦ λ ≦ 1) and preset at the phase correction timing, while taking into account the past effects to some extent, There is an effect that it becomes possible to follow the variation of the slot timing generated with the approach of the group.

It is a block diagram of the communication terminal of this Embodiment. It is a figure which shows a mode that two networks with respectively different reference | standard timings synthesize | combine. It is a graph which points out the problem in the case of adjusting a reference timing using the conventional average value. It is a flowchart which shows the feature extraction part processing program which the feature extraction part which concerns on 1st Embodiment performs. (A) shows a histogram with the number of sections S1, and (B) shows a histogram with the number of sections S2 (> S1). It is a timing chart which shows the size of the occupation rate of a slot. It is a flowchart which shows the reference | standard timing adjustment processing program which the clock correction | amendment part 32 concerning 2nd Embodiment performs. It is a flowchart which shows the feature extraction process program which the feature extraction part 28 which concerns on 3rd Embodiment performs. (A)-(D) are explanatory drawings explaining an effect | action in case the own timing is a minority. (A)-(D) are explanatory drawings explaining the process in case the own timing is majority. (A) is a histogram created without taking the reception level into consideration, (b) shows a histogram created using only signals whose reception level is equal to or higher than a certain value, and (c) is a reception level. It is a histogram when weighted according to. It is a block diagram of the communication terminal of 5th Embodiment. (A) And (B) is the graph which showed distribution of the reception timing shift | offset | difference amount of the own reference signal and the packet from a periphery terminal. It is a timing chart which shows that the speed to synchronization establishment changes with the method of taking a reference signal. FIG. 6 is a timing chart showing that the problem that the speed until the establishment of synchronization changes depending on how the reference signal is taken becomes particularly significant in synchronization in an autonomous distributed network. It is a flowchart which shows the processing program which the histogram (period expansion) production | generation part 110 and window processing part 120 concerning 5th Embodiment perform. It is explanatory drawing explaining the signal processing which considered the periodicity of the timing deviation amount. It is a figure which shows applying a histogram while extending a histogram by 1 period, shifting a window to this. (A)-(E) is a figure which shows the breadth of the histogram in the window of each position. It is a figure which shows the table | surface of the calculation result of three physical quantities which show the breadth of a histogram. It is a figure which shows the calculation result of three physical quantities which show the breadth of a histogram. It is a figure which shows the implementation result of this Embodiment and a prior art. It is a block diagram of the communication apparatus of 6th Embodiment. (A)-(D) is explanatory drawing explaining the detection processing content of the phase difference in a phase difference detection part, (A) shows the structure of a phase difference detection part, (B)-(D) FIG. 5 is a diagram showing a phase difference signal output in accordance with the phase difference. It is explanatory drawing explaining the principle which selects a counter based on a phase difference signal in a counter selection part. (A) is a block diagram of a received signal strength detector, and (B) is a timing chart showing an enable signal. It is the figure which showed the mode of the output of the counter control signal in a counter control signal generation part. It is a block diagram of a weighting window processing unit. (A)-(C) are explanatory drawings explaining the effect | action of 6th Embodiment. It is a block diagram of the communication apparatus of 7th Embodiment. (A)-(C) are explanatory drawings explaining the effect | action of 6th Embodiment.

Explanation of symbols

12 Antenna (receiving means)
24 Reference signal generator (detection means)
26 detector (creating means and specifying means)
28 Feature extraction unit (creating means and specifying means)
32 Clock correction unit (changing means)
110 Histogram (period extension) generator (creating means)
120 Window processing unit (calculation means)
152 Phase difference detector (creating means)
154 Counter selection unit (creating means)
156 Received signal strength detector (creating means)
158 Counter control signal generator (creating means)
160 Histogram generation unit (creation means, count value storage means)
162 Weighted window processing unit (calculation means)
164 Phase correction amount calculation unit (calculation means)
166 Slot timing generator (changing means, count value resetting means, count value decreasing means)
157 Offset addition unit (specifying means)
161 Data cyclic shift unit (specifying means)

Claims (17)

A communication device that communicates based on a predetermined reference timing,
Receiving means for receiving a plurality of signals transmitted from other communication devices based on each reference timing;
Detecting means for detecting a reference timing of each of the plurality of received signals;
Creating means for creating a histogram of phase differences between a reference timing of each of the detected signals and the predetermined reference timing;
Based on the created histogram, specifying means for specifying a phase difference with other communication terminals that can communicate with more other communication terminals by changing the predetermined reference timing;
Changing means for changing the predetermined reference timing based on the identified phase difference;
A communication device comprising:   2. The communication apparatus according to claim 1, wherein the specifying unit specifies the most frequent phase difference within at least a predetermined time range including the predetermined reference timing. The communication is repeated at regular intervals,
The predetermined time range exists within the predetermined time period;
A judgment means for judging whether or not a predetermined number of signals having a reference timing matching the predetermined reference timing are received within the predetermined time range;
The communication apparatus according to claim 2, wherein the creating unit changes an interval of the phase difference of the histogram according to a determination result of the determining unit. The communication is repeated at regular intervals,
The predetermined time range exists within the predetermined time period;
A determination means for determining whether there is a phase difference between other communication terminals capable of communicating with more other communication terminals when the predetermined reference timing is changed within the predetermined time range;
The specifying unit specifies an average of the phase differences as the phase difference when it is not determined by the determining unit, and specifies the most frequent phase difference when it is determined by the determining unit. ,
The communication device according to claim 2. The reference timing is determined based on any one of a plurality of areas obtained by dividing a predetermined time,
The communication is repeatedly performed at the predetermined time, and transmission and reception during the communication are performed while occupying any of the plurality of areas.
Further comprising grasping means for grasping the occupation state of the plurality of areas,
5. The communication apparatus according to claim 1, wherein the changing unit changes the predetermined reference timing by adjusting a change amount according to the grasped occupation state. 6. .   6. The detection unit according to claim 1, wherein the detection unit detects only the signal having a signal level equal to or higher than a predetermined value from the plurality of received signals, and detects the reference timing. The communication device according to item.   The communication apparatus according to claim 6, wherein the creating unit creates the phase difference histogram by weighting according to the signal level. A communication method for communicating based on a predetermined reference timing,
Receiving a plurality of signals transmitted from other communication devices based on each reference timing; and
Detecting a reference timing of each of the plurality of received signals;
Creating a histogram of phase differences between the reference timing of each of the plurality of detected signals and the predetermined reference timing;
Identifying a phase difference that can be communicated with more other communication terminals when the predetermined reference timing is changed based on the created histogram;
Changing the predetermined reference timing based on the identified phase difference;
A communication method comprising: A communication device that communicates based on a predetermined reference timing,
Receiving means for receiving a plurality of signals transmitted from other communication devices based on each reference timing;
Detecting means for detecting a reference timing of each of the plurality of received signals;
Creating means for creating a histogram of phase differences between a reference timing of each of the detected signals and the predetermined reference timing;
The created histogram is periodically expanded, and a calculation area determined in one period is determined by shifting a plurality of areas in the periodically expanded histogram, and the distribution state of the histogram at each position of the determined plurality of calculation areas A calculation means for calculating a physical quantity representing
Changing means for changing the predetermined reference timing based on the position of the determined calculation area and the physical quantity calculated by the calculating means;
A communication device comprising: The physical quantity representing the distribution state is a physical quantity representing the spread of the histogram,
The communication device according to claim 9, wherein the changing unit changes the predetermined reference timing based on a position of the calculation area where the spread of the histogram is minimized. A communication method for communicating based on a predetermined reference timing,
Receiving a plurality of signals transmitted from other communication devices based on each reference timing; and
Detecting a reference timing of each of the plurality of received signals;
Creating a histogram of phase differences between the reference timing of each of the plurality of detected signals and the predetermined reference timing;
The generated histogram is periodically expanded, a calculation area determined in one period is determined by periodically extending the plurality of shifts in the histogram, and the distribution state of the histogram at each position of the determined calculation areas Calculating a physical quantity representing
Changing the predetermined reference timing based on the position of the determined calculation area and the physical quantity calculated by the calculation means;
A communication method comprising:   The said preparation means weights each received said several signal according to a signal level, and produces the histogram of the said phase difference, The said any one of Claim 1 thru | or 6 characterized by the above-mentioned. Communication device. A communication device that communicates based on a predetermined reference timing,
Receiving means for receiving a plurality of signals transmitted from other communication devices based on each reference timing;
Detecting means for detecting a reference timing of each of the plurality of received signals;
Creating means for weighting each of the plurality of received signals according to a signal level and creating a histogram of phase differences between the reference timing of each of the detected plurality of signals and the predetermined reference timing;
A calculation means for calculating a physical quantity representing a distribution state of the histogram at a position of each of the determined plurality of calculation areas, while determining a plurality of predetermined calculation areas in the created histogram.
Changing means for changing the predetermined reference timing based on the position of the determined calculation area and the physical quantity calculated by the calculating means;
A communication device comprising: The physical quantity representing the distribution state is a physical quantity representing the spread of the histogram,
The communication device according to claim 13, wherein the changing unit changes the predetermined reference timing based on a position of the calculation area where the spread of the histogram is minimized. The creating means includes
A count value storage means for storing a count value for each of the plurality of phase differences,
The histogram is created by updating the count value of the counter value storage means corresponding to the phase difference of each signal with a value obtained by weighting each of the plurality of received signals according to the signal level. 15. The communication apparatus according to claim 13, wherein the communication apparatus is characterized.   The count value reset means for resetting the count value stored in each count value storage means of the creation means each time the predetermined reference timing is changed. Communication equipment. Count value decreasing means for decreasing the count value stored in each count value storing means of the creating means each time the predetermined reference timing is changed;
Each time the predetermined reference timing is changed, it is assumed that the phase difference corresponding to the count value storage means used as a reference when the predetermined reference timing was changed last time is zero, and the phase corresponding to each count value storage means. A specific means for identifying a phase difference value;
The communication device according to claim 13 or 14, further comprising:

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