JP2004242246A - Wireless communication terminal with time slot synchronization scheme - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize secured communication connectivity of a wireless communication terminal, with low power consumption as well. <P>SOLUTION: The wireless communication terminal includes a radio frequency modulator/demodulator 11; a synchronization detector 12; a scheduling manager 13 outputting a reception control signal by determining either no detection of a synchronization pattern yet or completion of packet reception, and outputting synchronization window period information; and a transmission/reception controller 14 suspending the reception operation in the radio frequency modulator/demodulator. The wireless communication terminal further includes a reception slot manager 15 for managing the number of continuous idle slots, based on the synchronization pattern detection information; and a window width calculator 16 for calculating a synchronization window width based on the number of the continuous idle slots, a criterion value of the synchronization window width, and a step value. Corresponding to the packet reception condition, a synchronization window width S10 is dynamically controlled. Thus, connectivity of communication connection, as well as low power consumption, is achieved. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wireless communication terminal using a variable synchronization window that can achieve good synchronous connectivity and low power consumption in a time slot synchronization method of a time division multiplex communication system.
[0002]
[Prior art]
The operation of a time slot synchronization system using a synchronization window in a conventional time division multiplex communication system and the configuration of a wireless communication terminal will be described.
[0003]
In FIG. 11, a synchronization pattern 202 is given to a packet 201 transmitted and received between wireless communication terminals. The slave terminal detects and corrects a time slot shift between the reference terminal and the slave terminal based on the packet reception timing sent from the reference terminal, that is, the detection timing of the synchronization pattern 202. The determination and detection of the synchronization pattern 202 are performed during a fixed width synchronization window 203 provided for capturing the synchronization pattern 202 in the reception slot. The synchronization window width is determined based on information such as the accuracy of the operation clock used by the reference terminal and the slave terminal, the minimum packet transmission / reception interval, and the time slot time. If a synchronization pattern cannot be detected in the synchronization window 203, it is early determined that the slot is an empty slot where no valid received packet exists, and the reception operation of the high-frequency modulation / demodulation unit is stopped to reduce power consumption. Has been realized.
[0004]
In the example of FIG. 11, the dependent terminal can capture the synchronization pattern 202 of the packet # 1 during the synchronization window 203, and corrects the slot timing. Similarly, the synchronization pattern 202 can be detected for the packet # 2. In the case of packet # 3, since the packet from the reference terminal cannot be received due to a communication error or the like, it is treated as an empty slot, and the reception operation of the high-frequency modulation / demodulation unit is stopped after the completion of the synchronization window.
[0005]
In FIG. 12, the control circuit of the wireless communication terminal 1000 using the time slot synchronization scheme having a synchronization window includes a high frequency modulation / demodulation unit 11, a synchronization detection unit 12, a scheduling management unit 13, and a transmission / reception control unit 14.
[0006]
The radio signal S1 received during the reception slot period, that is, the packet, is subjected to demodulation processing by the high-frequency modulation / demodulation unit 11, and then input to the synchronization detection unit 12 as a demodulated signal S2. The synchronization detection unit 12 performs a synchronization pattern determination and detection process in the synchronization window period based on the synchronization window period information S3 in the reception slot from the scheduling management unit 13. The synchronization pattern detection information S4 by the synchronization detection unit 12 is notified to the scheduling management unit 13. The scheduling management unit 13 corrects the timing of the time slot between the reference terminal and the dependent terminal, and the transmission / reception time slot based on the reference value S10 of the synchronization window width. Time management. The timing correction of the time slot is performed so as to match the timing with the reference terminal at the time of the dependent terminal. Further, when the synchronization pattern is not detected or the packet reception is completed, the reception control signal S5 notifies the transmission / reception control unit 14 of the reception operation stop. The transmission / reception control unit 14 notifies the control signal S6 for stopping the reception operation of the high-frequency modulation / demodulation unit 11, and the high-frequency modulation / demodulation unit 11 stops the reception operation.
[0007]
As described above, in the time slot synchronization method using the fixed width synchronization window, the function of stopping the reception operation of the high-frequency modulation / demodulation unit 11 achieves low power consumption during the idle slot period (for example, Non-Patent Document 1). reference).
[0008]
[Non-patent document 1]
Published by BLUETOOTH SIG, BLUETOOTH SPECIFICATION Version 1.1 February 22, 2001 Edition, Baseband Specification p. 84-86
[0009]
[Problems to be solved by the invention]
Conventional wireless communication terminals of the time slot synchronization method have a fixed synchronization window, so that when a period during which packet reception cannot be performed becomes longer due to deterioration of radio wave conditions on a wireless transmission path, a communication connection is established. Easy to be cut. It is important to maintain communication connection connectivity, and for that purpose, it is necessary to increase the synchronization window width and increase the frequency of packet transmission / reception. However, this makes it difficult to reduce the power consumption of the wireless communication terminal.
[0010]
In the example of FIG. 11, it is shown that packets # 4 to # N-1 cannot be received by the dependent terminal due to the radio wave condition of the wireless communication path. During this period, the time slot shift time between the reference terminal and the slave terminal is accumulated, and when the next packet #N is received, the accumulated amount of the time slot shift time exceeds the synchronization window width. Indicates that it cannot be caught. Thereafter, packet reception becomes impossible, and the communication connection is eventually disconnected.
[0011]
In other words, in order to prevent disconnection of the communication connection, it is necessary to guarantee the frequency of packet transmission from the reference terminal to the dependent terminal and to keep the accumulated amount of time slot shift time between wireless communication terminals within the range of the synchronization window width. However, in consideration of a case where packet transmission / reception cannot be performed due to the influence of deterioration of the radio wave condition of the wireless transmission path, it is necessary to add a sufficient margin to the packet transmission / reception frequency and increase the frequency.
[0012]
In addition, it is necessary to secure a sufficient margin in consideration of variations so that the synchronization window width can be applied to all wireless communication terminals, and to set the synchronization window width to an optimal small value only in a local environment between wireless communication terminals. Setting is not allowed.
[0013]
These circumstances make it difficult to simultaneously reduce power consumption of the wireless communication terminal and ensure communication connection connectivity.
[0014]
SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to achieve compatibility between securing communication connection of a wireless communication terminal and reducing power consumption.
[0015]
[Means for Solving the Problems]
The time slot synchronization wireless communication terminal according to the present invention changes the window width of the synchronization window to a variable length in accordance with the state of the reception slot.
[0016]
The first is a method of dynamically controlling the synchronization window width depending on the packet reception state. Monitors the status of packet reception for each time slot, that is, the use or unused status of the reception slot, and sets the synchronization window width to the step value interval from the reference value according to the number of continuations of the unused slots in the reception slot. To control. In addition, the method of adjusting the synchronization window width is changed according to the operation clock accuracy of the reference terminal and the subordinate terminal, the minimum packet transmission / reception interval, the operation mode between communication terminals, the time slot time, and the like. The details will be described later.
[0017]
The second is a dynamic control method of a synchronization window width using a correlation table between a packet reception state and a time slot fluctuation amount. The packet reception status of each time slot, that is, the use / non-use status of the reception slot is monitored, and the time slot fluctuation amount, which is the time lag between the synchronization pattern detection predicted time and the synchronization pattern detection time, is calculated, and the time slot is corrected. The correlation value between the number of time slots elapsed since the execution of the above operation and the amount of time slot fluctuation is held in a correlation table, and the held value is referred to based on the number of elapsed time slots to calculate a synchronization window width. Further, the calculation result obtained by statistically processing the time slot fluctuation amount is registered in the correlation table. Further, it holds a correlation table according to the operation mode such as the operation clock accuracy of the reference terminal and the slave terminal, the minimum packet transmission / reception interval, the mode between communication terminals, and the time slot time, and performs correction processing of reference data according to the operation mode. The details will be described later.
[0018]
Further, a reference value and a step value, which are parameters of the synchronization window width, are calculated based on the amount of time slot fluctuation when packet reception is continuously performed, and this parameter is used as the synchronization window width used in the first control method. Are used as update setting values of the correlation table between the reference value and the step value of the above and the packet reception state used in the second control method and the time slot fluctuation amount.
[0019]
With these configurations, it is possible to capture and detect a synchronization pattern even when normal packet transmission / reception cannot be performed due to the radio wave condition of the wireless transmission path or the like and a time slot shift time has accumulated. In addition, by controlling dynamic change of the synchronization window width according to the packet reception status and selecting the optimum synchronization window width in the local environment between wireless communication terminals, power consumption is reduced by reducing the frequency of packet transmission and reception, and communication connection connection is reduced. Simultaneous improvement of the performance can be realized.
[0020]
More specifically, the following can be said.
[0021]
As a first solution, a wireless communication terminal according to the present invention comprises a high frequency modulation / demodulation means for performing a modulation / demodulation process of a radio signal, and a synchronization pattern detected and detected from a demodulated signal by the high frequency modulation / demodulation means based on input synchronization window period information. Synchronization detection means for outputting pattern detection information, and inputting the synchronization pattern detection information from the synchronization detection means, determining whether a synchronization pattern has not been detected or completing packet reception, outputting a reception control signal, and managing time of transmission / reception time slots. And a timing correction, and a scheduling management unit that outputs the synchronization window period information to the synchronization detection unit; and a control signal for stopping a reception operation to the high-frequency modulation / demodulation unit based on the reception control signal from the scheduling management unit. Time slot with transmission / reception control means for outputting A wireless communication terminal phases method further includes the following means. That is, a reception slot management unit that manages the number of continuations of empty slots based on the synchronization pattern detection information by the synchronization detection unit, and a reference value and a step value of the number of continuations of empty slots and the synchronization window width by the reception slot management unit. Window width calculating means for calculating a synchronization window width based on the above, and outputting the synchronization window width to the scheduling management means for time management of the transmission / reception time slot and timing correction.
[0022]
The operation of this configuration is as follows. Upon detecting the synchronization pattern, the synchronization detection means outputs synchronization pattern detection information to the scheduling management means and the reception slot management means. The receiving slot management means, which has received the synchronization pattern detection information, manages the number of continuations of unused empty slots in the receiving slot and outputs the number of continuations of empty slots to the window width calculating means. The window width calculating means, which has input the number of free slots, calculates the sync window width using the reference value and the step value of the sync window width and the number of free slots.
[0023]
For example, assuming that the reference value of the synchronization window width is Wo, the step value for adjusting the synchronization window width is Ws, and the continuation number of empty slots is n, the synchronization window width W is
W = Wo + n · Ws
The window width calculation means calculates the synchronization window width by, for example, such an operation. Then, the calculated synchronization window width is given to the scheduling management means. The scheduling management means generates synchronization window period information based on the input synchronization window width, and outputs the information to the synchronization detection means. The synchronization detecting means detects a synchronization packet in a given synchronization window period. Further, when the scheduling management means does not detect the synchronization pattern within a predetermined time or determines that the packet reception is completed, the scheduling management means stops the reception operation of the high frequency modulation / demodulation means via the transmission / reception control means by the reception control signal.
[0024]
As described above, the configuration is such that the synchronization window width for capturing the synchronization pattern is dynamically controlled in accordance with the reception state of the packet. Thus, the communication connection connectivity can be ensured by using the optimum synchronization window width, and unnecessary power consumption can be avoided to realize low power consumption.
[0025]
As a second solution, the wireless communication terminal according to the present invention, in the first solution, further comprises an operation mode determining means for determining an operation mode at a specified timing, and a reference value of a synchronization window width for each operation mode. A window parameter selecting unit that has a step value, selects a reference value and a step value of the synchronous window width corresponding to the operation mode determined by the operation mode determining unit, and outputs the selected value to the window width calculating unit. It has been.
[0026]
The operation of this configuration is as follows. The operation modes of the wireless communication terminal include the accuracy of the operation clock used by the reference terminal and the slave terminal, the communication mode defined between the wireless communication terminals, the minimum packet transmission / reception interval, the time slot time, and the like. Each operation mode has an optimum synchronization window width. To cope with this, the current operation mode is determined by the operation mode determination means, and the window parameter selection means selects the optimal window width reference value and step value according to the obtained operation mode, and the window width calculation means Give (multi-window parameter selection function). For example, in the case of a mode using a low-speed clock with low clock accuracy used in the reference terminal or the slave terminal, the fluctuation amount of the time slot shift becomes large, so that the window width reference value and the step value are set large. Here, both the synchronization window width reference value Wo and the step value Ws may be used as adjustment elements, or only one of them may be used as an adjustment element. This makes it possible to dynamically control the optimum window width in accordance with the operation mode, and to further improve the communication connection connectivity and reduce the power consumption of the wireless communication terminal. .
[0027]
As a third solution, the wireless communication terminal according to the present invention, in the first solution, further comprises a time difference between a detection time of the synchronization pattern by the synchronization detection means and a prediction time by the scheduling management means. A time slot fluctuation amount calculating means for calculating a time slot fluctuation amount; and a window width calculating means based on the time slot fluctuation amount by the time slot fluctuation amount calculating means and the free slot continuation number by the reception slot managing means. Window width reference value calculating means for calculating the reference value of the synchronous window width.
[0028]
The operation of this configuration is as follows. Originally, the reference value of the synchronization window includes a certain margin so that it can be applied to all wireless communication terminals. However, a local environment in which wireless communication is currently performed has its own unique conditions. Therefore, a time slot fluctuation amount calculating unit is provided to check the current communication condition, and a time difference between a predicted time detected by the scheduling management unit and a synchronization pattern detection time detected by the synchronization detecting unit, that is, a time slot fluctuation amount is calculated. Then, the window width reference value calculating means calculates a window width reference value based on the time slot fluctuation amount and the number of free slots, and calculates an optimum window width reference value for the obtained local wireless communication environment. Give to the means.
[0029]
For example, the obtained time slot fluctuation amount is ΔT, and the window width reference value calculated by the window width reference value calculating means based on the time slot fluctuation amount ΔT, the number n of free slots and the original synchronization window width reference value Wo. Value Wo_TnThen, Wo_Tn= F (Wo, ΔT, n). And the synchronization window width W is
W = Wo_Tn+ NWs
Can be represented by This enables dynamic control of the optimal window width according to the local wireless communication environment, and can further improve communication connection connectivity and lower power consumption as a wireless communication terminal.
[0030]
According to a fourth aspect of the present invention, in the wireless communication terminal according to the first aspect of the present invention, the wireless communication terminal further includes a time lag between a synchronization pattern detection time by the synchronization detection means and a detection prediction time by the scheduling management means. A time slot fluctuation amount calculating means for calculating a time slot fluctuation amount; and a window width calculating means based on the time slot fluctuation amount by the time slot fluctuation amount calculating means and the free slot continuation number by the reception slot managing means. A window width step value calculating means for calculating a step value of the synchronous window width.
[0031]
This is to adapt the step value to the local environment instead of the window width reference value to the local environment. That is, in order to check the condition of the current communication, the time slot fluctuation amount calculating means is provided to calculate the time slot fluctuation amount in the same manner as described above. Then, the window width step value calculating means calculates a step value of the synchronization window width based on the time slot fluctuation amount and the number of free slots, and calculates an optimum step value for the obtained local wireless communication environment. Give to the means.
[0032]
For example, the obtained time slot fluctuation amount is defined as ΔT, and the step value calculated by the window width step value calculating means based on the time slot fluctuation amount ΔT, the number of continuous empty slots n, and the original step value Ws is represented by Ws_TnThen, Ws_Tn= G (Ws, ΔT, n). And the synchronization window width W is
W = Wo + n · Ws_Tn
Can be represented by This enables dynamic control of the optimal window width according to the local wireless communication environment, and can further improve communication connection connectivity and lower power consumption as a wireless communication terminal.
[0033]
According to a fifth aspect of the present invention, in the wireless communication terminal according to the first aspect of the present invention, the wireless communication terminal according to the first aspect further comprises a time lag between a synchronization pattern detection time by the synchronization detection means and a detection prediction time by the scheduling management means. Time slot fluctuation amount calculating means for calculating a time slot fluctuation amount, and correction of a time slot based on the time slot fluctuation amount by the time slot fluctuation amount calculating means and the number of free slots continued by the reception slot managing means. A time slot fluctuation amount holding means for obtaining a correlation value between the number of elapsed time slots after the execution and the time slot fluctuation amount and storing the obtained correlation value in a correlation table is provided. Then, the window width calculating unit searches the time slot fluctuation amount holding unit based on the number of continuations of the empty slots from the reception slot management unit, and performs the correlation based on the number of elapsed time slots based on the number of continuations of the empty slots. It is configured to calculate the synchronization window width with reference to the correlation value in a table.
[0034]
The operation of this configuration is as follows. This also examines the state in the local wireless communication environment on the spot, and in the time slot fluctuation amount holding means, obtains statistics on the correlation value between the number of elapsed time slots and the time slot fluctuation amount, and stores the obtained correlation value in a correlation table. I keep it.
[0035]
Wo sets the window width reference value and step value that are optimal for the local wireless communication environment._Tn= F (Wo, ΔT, n) or Ws_Tn= G (Ws, ΔT, n) is measured as actual data according to the actual situation, rather than being calculated by the function. The resulting correlation values in the correlation table have higher accuracy than those calculated. It generally has non-linear characteristics. As a result, normal packet transmission / reception cannot be performed due to the radio wave condition of the wireless transmission path and the like, and even when a time slot shift is accumulated, a synchronization pattern can be detected. In addition, the window width control with respect to the number of vacant slots has a non-linear characteristic by the flexible setting of the time slot fluctuation amount for each continuation of the vacant slots and the registration function of the synchronization window width which is optimal in a local environment between wireless communication terminals. It is possible to further improve communication connection connectivity and reduce power consumption as a wireless communication terminal.
[0036]
According to a sixth aspect of the present invention, in the wireless communication terminal according to the fifth aspect, the time slot fluctuation amount calculated by the time slot fluctuation amount calculating means and the number of free slots continued by the reception slot managing means are further increased. A window width reference value calculating means for calculating the reference value of the synchronous window width based on the reference value, and a reference for controlling registration of the reference value or its correction value by the window width reference value calculating means to the time variation holding means. And a value update control unit.
[0037]
The operation of this configuration is as follows. Since the window width reference value calculation means actively calculates the synchronization window width reference value, the time until the entire area of the correlation table of the time slot fluctuation amount holding means is reset by packet transmission / reception between wireless communication terminals is waited. Without delay, it is possible to register the reference value in the optimal correlation table at an early stage, and realize low power consumption as a wireless communication terminal by shortening the response time to activation of the correlation table when establishing a communication connection. it can.
[0038]
According to a seventh aspect of the present invention, in the wireless communication terminal according to the fifth aspect, the time slot fluctuation amount calculated by the time slot fluctuation amount calculating means and the number of free slots continued by the reception slot managing means are further increased. A variation calculation processing means for performing a statistical calculation process of the time slot variation in accordance with the number of continuations of the vacant slot, and a registration of the calculation result by the variation calculation processing in the time slot variation holding means. And a statistic update control unit for controlling.
[0039]
The operation of this configuration is as follows. The information obtained by statistically processing the time slot fluctuation amount accumulated by the past wireless communication for each empty slot between the wireless communication terminals can be selected as the synchronization window width. The communication connection connectivity based on the window width reference value or the step value that suppresses temporal fluctuation and low power consumption can be realized.
[0040]
As an eighth solution means, the wireless communication terminal according to the present invention, in the fifth solution means, further comprises: an operation mode determining means for determining an operation mode at a prescribed timing; and an operation mode determined by the operation mode determination means. Table update control means for restricting registration access to the time slot fluctuation amount holding means, and correction calculation for correcting a correlation value referred to by the time slot fluctuation amount holding means according to the operation mode by the operation mode determination means And means.
[0041]
The operation of this configuration is as follows. Since the correlation value is corrected according to the operation mode, only one correlation table may be used for a specific operation mode. Even in a wireless communication terminal that supports a plurality of operation modes, the correlation mode can be reduced while suppressing the circuit scale. It is possible to dynamically control the width of the synchronization window according to the situation.
[0042]
As a ninth solution means, the wireless communication terminal according to the present invention, in the fifth solution means, comprises a plurality of the time slot variation holding means corresponding to each operation mode, and further determines the operation mode at a specified timing. Operating mode discriminating means, and a table updating control means for selecting one of the plurality of time slot fluctuation amount holding means in accordance with the operation mode by the operation mode discriminating means.
[0043]
The operation of this configuration is as follows. Even in a wireless communication terminal that supports multiple operation modes, it is possible to dynamically control the synchronization window width according to the operation mode, and to realize fine-grained control with a window width optimized for each operation mode, It is possible to further improve the communication connection connectivity as a terminal and reduce power consumption.
[0044]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a time slot synchronous wireless communication terminal according to the present invention will be described in detail with reference to the drawings.
[0045]
In FIG. 1, a synchronization pattern 102 is provided to a packet 101 transmitted and received between wireless communication terminals. The slave terminal detects and corrects a time slot shift between the reference terminal and the slave terminal based on the packet reception timing sent from the reference terminal, that is, the detection timing of the synchronization pattern 102. The determination and detection of the synchronization pattern 102 are performed during a variable-length synchronization window 103 provided for capturing the synchronization pattern 102 in a reception slot. The synchronization window width is determined according to the reception state of the packet 101, that is, the continuous number of empty slots. As a result, even if packet transmission / reception between wireless communication terminals cannot be performed for a certain period of time and time slot shift times accumulate, the synchronization pattern 102 for the next received packet can be captured, and communication connection connectivity can be improved. Can be. Further, for the next reception slot in which the synchronization pattern 102 can be detected, the synchronization pattern 102 for the received packet can be captured even if the synchronization window width is used as a reference value.
[0046]
Even in the situation where the synchronization window width is varied according to the packet reception state, when the synchronization pattern 102 cannot be detected in the synchronization window 103, the slot is an empty slot where no valid reception packet exists. , And the reception operation of the high-frequency modulation / demodulation unit is stopped, thereby realizing low power consumption.
[0047]
In the example of FIG. 1, the dependent terminal can capture the synchronization pattern 102 for the packet # 1 during the synchronization window 103, and corrects the slot timing. Similarly, the synchronization pattern 102 can be detected for the packet # 2. In the case of packet # 3, since the packet from the reference terminal cannot be received due to a communication error or the like, it is treated as an empty slot, and the reception operation of the high-frequency modulation / demodulation unit is stopped after the completion of the synchronization window. Further, packets # 4 to # N-1 indicate that packets cannot be received due to the radio wave condition of the wireless communication path or the like. During this period, the time lag of the time slot between the reference terminal and the slave terminal is accumulated, but the synchronization window width is expanded in conjunction with the number of free slots. Therefore, the synchronization pattern 102 can be captured even when the packet #N is received. When the next packet # N + 1 is received, the synchronization pattern is detected in the previous slot, that is, since the number of empty slots is zero, the synchronization window width is returned to the reference value and the synchronization pattern 102 is captured.
[0048]
As described above, the dynamic change control of the synchronization window width according to the packet reception state and the calculation control of the optimum synchronization window width in the local environment between the wireless communication terminals reduce the power consumption by reducing the frequency of packet transmission and reception. Simultaneous realization of improvement of communication connection connectivity becomes possible.
[0049]
(Embodiment 1)
As shown in FIG. 2, radio communication terminal 100 according to Embodiment 1 of the present invention has high-frequency modulation / demodulation unit 11, synchronization detection unit 12, scheduling management unit 13, transmission / reception control unit 14, reception slot management unit 15, window width calculation unit 16 and has a function of dynamically controlling the synchronization window width in accordance with the packet reception state.
[0050]
The radio signal S1 received during the reception slot period, that is, the packet, is subjected to demodulation processing by the high frequency modulation / demodulation unit 11, and then input to the synchronization detection unit 12 as a demodulated signal S2. The synchronization detection unit 12 determines and detects a synchronization pattern in the synchronization window period based on the synchronization window period information S3 in the reception slot from the scheduling management unit 13. The synchronization pattern detection information S4 by the synchronization detection unit 12 is notified to the scheduling management unit 13. The scheduling management unit 13 corrects the timing of the time slot between the reference terminal and the dependent terminal and manages the time of the transmission / reception time slot based on the synchronization window width S10 from the window width calculation unit 16. The timing correction of the time slot is performed so as to match the timing with the reference terminal at the time of the dependent terminal. Further, when the synchronization pattern is not detected or the packet reception is completed, the reception control signal S5 notifies the transmission / reception control unit 14 that the reception operation has stopped. The transmission / reception control unit 14 notifies the control signal S6 for stopping the reception operation of the high-frequency modulation / demodulation unit 11, and the high-frequency modulation / demodulation unit 11 stops the reception operation.
[0051]
The synchronization pattern detection information S4 by the synchronization detection unit 12 is also notified to the reception slot management unit 15 as a packet reception state for each time slot. The reception slot management unit 15 manages the number of continuations S7 of the unused empty slots in the reception slot based on the synchronization pattern detection information S4. For example, it counts up when an empty slot is detected, and clears the count when a synchronization pattern is detected. That is, it manages information corresponding to the number of slots that have elapsed since the timing of the time slot was corrected by detecting the synchronization pattern. The continuation number S7 of the empty slots is notified to the window width calculation unit 16. The window width calculation unit 16 calculates the synchronization window width S10 using the synchronization window width reference value S8 and the step value S9. As a method of calculating the synchronization window width S10, there is a method of assigning a step value S9 to one or a plurality of empty slots and controlling at a step value interval from the reference value S8. At this time, an upper threshold may be set for the synchronization window width S10.
[0052]
As a result, normal packet transmission / reception cannot be performed due to the radio wave condition of the wireless transmission path and the like, and the synchronization pattern can be detected even when the time slot shift time is accumulated. Further, since the synchronization window width can be increased, the frequency of packet transmission / reception for securing a communication connection between the reference terminal and the slave terminal can be reduced, and low power consumption as a wireless communication terminal can be realized. .
[0053]
(Embodiment 2)
Further, as shown in FIG. 3, the wireless communication terminal 200 according to the second embodiment of the present invention further includes an operation mode determining unit 17 and a window parameter selecting unit 18 in the first embodiment, and a plurality of window parameters are provided. That is, a function of selecting and assigning a reference value S8a and a step value S9a, which are optimal window parameters according to the operation mode information S11 by the operation mode discriminating unit 17, from a pair of the window step value and the reference value is provided. It is something.
[0054]
The operation mode of the wireless communication terminal includes the accuracy of the operation clock used by the reference terminal and the slave terminal, the communication mode defined between the wireless communication terminals, and the like, and a window parameter corresponding to the operation mode is set. For example, in the case of a mode using a low-speed clock with a low clock accuracy used in the reference terminal or the slave terminal, the amount of change in the time slot shift becomes large, so that the window width reference value and the step value are set large. The operation mode of the wireless communication terminal is determined by the operation mode determination unit 17 at an arbitrary timing, for example, at each start timing of the reception slot, and the operation mode information S11 obtained by the determination is notified to the window parameter selection unit 18. The window parameter selection unit 18 selects a reference value S8a and a step value S9a, which are window parameters according to the notified operation mode information S11, and notifies the window width calculation unit 16 of the selection. The window width calculation unit 16 calculates the synchronization window width S10 using the reference value S8a, the step value S9a, and the number of consecutive empty slots S7.
[0055]
This enables dynamic control of the optimal window width according to the operation mode, and achieves improvement in communication connection connectivity and low power consumption as a wireless communication terminal.
[0056]
(Embodiment 3)
In addition, as shown in FIG. 4, the wireless communication terminal 300 according to the third embodiment of the present invention further includes a time slot variation calculating unit 19 and a window width reference value calculating unit 20 in the first embodiment, It has a function that can be assigned as a reference value S8b of the synchronization window width at the time of calculating the synchronization window width using the time slot fluctuation amount S13 between the wireless communication terminals.
[0057]
The synchronization pattern detection information S4 from the synchronization detection unit 12 is notified to the time slot fluctuation amount calculation unit 19. The time slot fluctuation amount calculation unit 19 calculates the time slot fluctuation amount S13 based on the synchronization pattern detection predicted time S12 calculated by the scheduling management unit 13 and notifies the window width reference value calculation unit 20 of the time slot fluctuation amount S13. The window width reference value calculating unit 20 determines whether the number of empty slots is zero, that is, based on the time slot variation S13 and the number of continuous empty slots S7 managed by the receiving slot managing unit 15, that is, when a synchronous pattern is detected in a continuous receiving slot. The time slot fluctuation amount S13 is calculated and held as a reference fluctuation amount for one reception slot, and a result of performing correction such as margin addition is notified to the window width calculation unit 16 as a synchronization window width reference value S8b. The window width reference value calculation unit 20 can be set externally, for example, from a control microcomputer, and can set a value having a sufficient margin in advance in consideration of the performance of the wireless communication terminal or the like as an initial value. In addition, the window width reference value calculation unit 20 may perform access control so that calculation and registration can be selected.
[0058]
The window width calculation unit 16 calculates the synchronization window width S10 using the reference value S8b, the step value S9b of the synchronization window width, and the number of continuous empty slots S7.
[0059]
In the above embodiment, by setting the window width step value S9b to zero, a function having a fixed value synchronization window with the synchronization window width as the reference value S8b can also be realized.
[0060]
This makes it possible to set an optimum synchronization window width reference value between wireless communication terminals. Originally, the reference value of the synchronization window includes a certain margin so that it can be applied to all wireless communication terminals, but the reference value of the optimum small synchronization window width can be used in a local environment between wireless communication terminals. Thus, low power consumption as a wireless communication terminal can be realized.
[0061]
(Embodiment 4)
In addition, radio communication terminal 400 according to Embodiment 4 of the present invention further includes a time slot variation calculating section 19 and a window width step value calculating section 21 in Embodiment 1 as shown in FIG. It is provided with a function that can be assigned as a step value S9c of the synchronization window width at the time of calculating the synchronization window width using the time slot fluctuation amount S13 between the communication terminals.
[0062]
The synchronization pattern detection information S4 from the synchronization detection unit 12 is notified to the time slot fluctuation amount calculation unit 19. The time slot fluctuation amount calculation unit 19 calculates the time slot fluctuation amount S13 based on the synchronization pattern detection predicted time S12 calculated by the scheduling management unit 13, and notifies the window width step value calculation unit 21. The window width step value calculation unit 21 determines whether the number of empty slots is zero, that is, based on the time slot variation S13 and the number of continuous empty slots S7 managed by the reception slot management unit 15. The time slot fluctuation amount S13 is calculated and held as a reference fluctuation amount for one reception slot, and the result of the correction such as margin addition is notified to the window width calculation unit 16 as the step value S9c of the synchronous window width. Note that the window width step value calculation unit 21 can be set from outside, for example, from a control microcomputer, and can set a value having a sufficient margin as the initial value in consideration of the performance of the wireless communication terminal in advance. In addition, the window width step value calculation unit 21 may perform access control so that calculation and registration availability can be selected. The window width calculation unit 16 calculates the synchronization window width S10 using the step value S9c, the reference value S8c of the synchronization window width, and the number of continuations of empty slots S7.
[0063]
This makes it possible to set an optimal synchronization window width step value between wireless communication terminals. Originally, the step value of the synchronization window includes a certain margin so that it can be applied to all wireless communication terminals, but since the step value of the optimal small synchronization window width can be used in a local environment between the wireless communication terminals, Thus, low power consumption as a wireless communication terminal can be realized.
[0064]
(Embodiment 5)
Further, as shown in FIG. 6, radio communication terminal 500 according to Embodiment 5 of the present invention further includes a time slot fluctuation amount calculating section 19 and a time slot fluctuation amount holding section 22 in Embodiment 1. And a function of calculating a synchronization window width S10 using a correlation table between the number of empty slots and the amount of time variation created based on the reference amount of variation for each time slot between wireless communication terminals.
[0065]
The radio signal S1 received during the reception slot period, that is, the packet, is subjected to demodulation processing by the high frequency modulation / demodulation unit 11, and then input to the synchronization detection unit 12 as a demodulated signal S2. The synchronization detection unit 12 determines and detects a synchronization pattern in the synchronization window period based on the synchronization window period information S3 in the reception slot from the scheduling management unit 13. The synchronization pattern detection information S4 by the synchronization detection unit 12 is notified to the scheduling management unit 13. The scheduling management unit 13 corrects the timing of the time slot between the reference terminal and the dependent terminal and manages the time of the transmission / reception time slot based on the synchronization window width S10 from the window width calculation unit 16. The timing correction of the time slot is performed so as to match the timing with the reference terminal at the time of the dependent terminal. Further, when the synchronization pattern is not detected or the packet reception is completed, the reception control signal S5 notifies the transmission / reception control unit 14 of the reception operation stop. The transmission / reception control unit 14 notifies the control signal S6 for stopping the reception operation of the high-frequency modulation / demodulation unit 11, and the high-frequency modulation / demodulation unit 11 stops the reception operation.
[0066]
Further, the synchronization pattern detection information S4 by the synchronization detection unit 12 is notified to the reception slot management unit 15 as a packet reception state for each time slot. The reception slot management unit 15 manages the number of continuations S7 of the unused empty slots in the reception slot based on the synchronization pattern detection information S4. For example, it counts up when an empty slot is detected, and clears the count when a synchronization pattern is detected. That is, it manages information corresponding to the number of slots that have elapsed since the timing of the time slot was corrected by detecting the synchronization pattern.
[0067]
Further, the synchronization pattern detection information S4 from the synchronization detection unit 12 is notified to the time slot fluctuation amount calculation unit 19. The time slot fluctuation amount calculation unit 19 calculates the time slot fluctuation amount S13 based on the synchronization pattern detection predicted time S12 calculated by the scheduling management unit 13, and notifies the time slot fluctuation amount holding unit 22. The time slot change amount holding unit 22 is configured as a correlation table 22a that holds a correlation value between the number of elapsed time slots after the time slot correction is performed and the time slot change amount S13.
[0068]
Note that the correlation table 22a may have a time slot fluctuation amount S13 for each time slot, for each fixed time slot interval, or for each time slot area using the area designation threshold. Further, it is also possible to provide the upper limit threshold value to the number of time slots and manage the time slot fluctuation amount S13 with respect to the number of time slots equal to or more than a certain number by a representative value. In the case where management is performed using a plurality of timeslots or the number of timeslots for each area, a value corresponding to the maximum value of the number of timeslots in the corresponding section can be assigned as a representative value of the time slot variation S13.
[0069]
The correlation table 22a can be set externally, for example, from a control microcomputer, and a value having a sufficient margin can be set as an initial value in consideration of the performance of the wireless communication terminal or the like in advance.
[0070]
When the synchronization pattern is detected, it is registered in the correlation table 22a of the time slot fluctuation amount holding unit 22 based on the information of the time slot fluctuation amount S13 and the number of free slots S7 of the reception slot management unit 15. In the registration in the correlation table 22a, whether or not registration is possible may be selected, and update access control to the correlation table 22a may be performed.
[0071]
The window width calculation unit 16 refers to the correlation value S14 from the correlation table 22a of the time slot fluctuation amount holding unit 22 based on the number of free slots S7 of the reception slot management unit 15 every time the reception slot is activated, and obtains the synchronization window width S10. Is calculated.
[0072]
As a result, normal packet transmission / reception cannot be performed due to the radio wave condition of the wireless transmission path and the like, and even when a time slot shift is accumulated, a synchronization pattern can be detected. In addition, the window width control with respect to the number of vacant slots has a non-linear characteristic by the flexible setting of the time slot fluctuation amount for each continuation of the vacant slots and the registration function of the synchronization window width which is optimal in a local environment between wireless communication terminals. Therefore, it is possible to realize communication connection connectivity and optimization of low power consumption as a wireless communication terminal.
[0073]
(Embodiment 6)
The wireless communication terminal 600 according to the sixth embodiment of the present invention further includes a window width reference value calculation unit 23 and a reference value update control unit 24 in the fifth embodiment as shown in FIG. A function is provided that can be registered as a setting reference value in the correlation table of the time slot variation holding unit 22 using the time slot variation S13 between terminals.
[0074]
In the window width reference value calculation unit 23, the number of empty slots, that is, the number of consecutive reception slots, is zero based on the time slot fluctuation amount S13 of the time slot fluctuation amount calculation unit 19 and the continuous number of empty slots S7 managed by the reception slot management unit 15. Assuming that the time slot fluctuation amount S13 when the synchronization pattern is detected in step (1) is the reference fluctuation amount for one reception slot, the correction such as margin addition and the fluctuation amount for each number of time slots are calculated, and the synchronization window width reference value S15 is used as a reference. The value is registered in the correlation table of the time slot fluctuation amount holding unit 22 via the value update control unit 24. In addition, in registration in the correlation table, it is possible to select an arbitrary area, for example, an unupdated area.
[0075]
Thus, the reference value can be registered in the optimum correlation table at an early stage without waiting for the time until the entire area of the correlation table of the time slot fluctuation amount holding unit is reset by the packet transmission and reception between the wireless communication terminals. In addition, it is possible to reduce the power consumption of the wireless communication terminal by shortening the response time to the activation of the correlation table when the communication connection is established.
[0076]
(Embodiment 7)
The wireless communication terminal 700 according to the seventh embodiment of the present invention further includes a variation calculation processing unit 25 and a statistic update control unit 26 in the fifth embodiment as shown in FIG. It has a function of registering a fluctuation amount statistical value S18 obtained by statistically processing the time slot fluctuation amount S13 in the correlation table of the time slot fluctuation amount holding unit 22.
[0077]
Each time a synchronization pattern is detected by the synchronization detection unit 12, the information on the time slot fluctuation amount S13 from the time slot fluctuation amount calculation unit 19 and the number of free slot continuations S7 from the reception slot management unit 15 are notified to the fluctuation amount calculation processing unit 25. Is done. The fluctuation amount calculation processing unit 25 calculates and collects statistical information for each of the continuous number of free slots S7. The fluctuation amount statistical value S18 includes a maximum value, a minimum value, an average value of the time slot fluctuation amount S13 calculated up to now, and a margin addition to the time slot fluctuation amount S13. The required statistical operation can be selected. The fluctuation amount statistical value S18 is stored in the correlation table of the time slot fluctuation amount holding unit 22 via the statistical value update control unit 26 at an arbitrary timing, for example, when a certain period of time elapses or when the accumulation of the sample of the certain number of time slot fluctuation amounts S13 is completed. Will be transferred.
[0078]
With this, it is possible to select, as the synchronization window width, information obtained by statistically processing the time slot fluctuation amount accumulated by the past wireless communication for each empty slot between the wireless communication terminals. It is possible to realize communication connection connectivity based on the window width reference value / step value with suppressed fluctuation and low power consumption.
[0079]
(Embodiment 8)
The wireless communication terminal 800 according to the eighth embodiment of the present invention further includes an operation mode determination unit 29, a table update control unit 27, and a correction operation unit 28 in the fifth embodiment as shown in FIG. It has a function of performing a correction operation based on the operation mode information S22 on the correlation value S21 from the correlation table of the slot fluctuation amount holding unit 22.
[0080]
The operation mode of the wireless communication terminal includes the accuracy of an operation clock used by the reference terminal and the slave terminal, a communication mode defined between the wireless communication terminals, and the like. The operation mode determination unit 29 determines the operation mode of the wireless communication terminal at an arbitrary timing, for example, at each reception slot activation timing, and notifies the table update control unit 27 and the correction operation unit 28 of the operation mode information S22. When the synchronization pattern is detected, it is registered in the correlation table of the time slot fluctuation amount holding unit 22 via the table update control unit 27 based on the information of the time slot fluctuation amount S13 and the number S7 of vacant slots in the reception slot management unit 15. . Since it is necessary to store a correlation value for a single operation mode in the correlation table, the table update control unit 27 restricts access to the correlation table based on the operation mode information S22 of the operation mode determination unit 29. The correction calculation unit 28 performs a correction process on the correlation value S21 from the correlation table of the time slot fluctuation amount holding unit 22 based on the operation mode information S22. For example, in the case of a mode using a low-speed clock with a low clock accuracy used in the reference terminal or the slave terminal, a process of increasing the correlation value at a constant rate is performed because the amount of fluctuation of the time slot shift increases. The correction value S23 of the correction processing result is notified to the window width calculation unit 16, and the synchronization window width S10 is calculated.
[0081]
As a result, even in a wireless communication terminal that supports a plurality of operation modes, it is possible to dynamically control the synchronization window width according to the operation mode, and the circuit scale can be increased by having only a correlation table for a specific operation mode. It can also be suppressed.
[0082]
(Embodiment 9)
Further, as shown in FIG. 10, the wireless communication terminal 900 according to the ninth embodiment of the present invention is different from the fifth embodiment in that the operation mode discrimination unit 29 and the time slot fluctuation amount holding units 22a to 22n which can be managed for each operation mode are added. And a table update control unit 30 are added, and a correlation table between the number of empty slots and the amount of time variation created based on the reference amount of time slot variation between wireless communication terminals is provided for each operation mode.
[0083]
The operation mode of the wireless communication terminal includes the accuracy of the operation clock used in the reference terminal and the slave terminal, the communication mode defined between the terminals, and the like. The operation mode determination unit 29 determines the operation mode of the wireless communication terminal at an arbitrary timing, for example, at each activation timing of the reception slot, and notifies the table update control unit 30 of the operation mode information S22 of the determination result. When the synchronization pattern is detected, it is registered in the correlation table of the time slot variation holding unit 22 via the table update control unit 30 based on the information on the time slot variation S13 and the number S7 of vacant slots in the reception slot management unit 15. . The table update control unit 30 controls access to the correlation table corresponding to the operation mode. In addition, every time the reception slot is activated, the window width is referred to by referring to the correlation value S25 from the time slot fluctuation amount holding unit 22 for each operation mode based on the number S7 of vacant slots in the reception slot management unit 15 and the operation mode information S22. The calculation unit 16 calculates the synchronization window width S10.
[0084]
As a result, even in a wireless communication terminal that supports a plurality of operation modes, it is possible to dynamically control the synchronization window width according to the operation mode, and to realize fine control using a window width optimized for each operation mode. In addition, communication connection connectivity as a wireless communication terminal and low power consumption can be realized.
[0085]
【The invention's effect】
As described above, according to the present invention, the synchronization window width for capturing the synchronization pattern is dynamically controlled in accordance with the reception state of the packet. In addition, it is possible to secure communication connection connectivity by using an optimum synchronization window width between wireless communication terminals, and to achieve low power consumption by avoiding unnecessary power consumption.
[Brief description of the drawings]
FIG. 1 is a time slot operation diagram showing the essence of functions in a wireless communication terminal of the present invention.
FIG. 2 is a block diagram showing a configuration of a wireless communication terminal according to Embodiment 1 of the present invention.
FIG. 3 is a block diagram showing a configuration of a wireless communication terminal according to Embodiment 2 of the present invention.
FIG. 4 is a block diagram showing a configuration of a wireless communication terminal according to Embodiment 3 of the present invention.
FIG. 5 is a block diagram showing a configuration of a wireless communication terminal according to Embodiment 4 of the present invention.
FIG. 6 is a block diagram showing a configuration of a wireless communication terminal according to a fifth embodiment of the present invention.
FIG. 7 is a block diagram showing a configuration of a wireless communication terminal according to Embodiment 6 of the present invention.
FIG. 8 is a block diagram showing a configuration of a wireless communication terminal according to a seventh embodiment of the present invention.
FIG. 9 is a block diagram showing a configuration of a wireless communication terminal according to Embodiment 8 of the present invention.
FIG. 10 is a block diagram showing a configuration of a wireless communication terminal according to Embodiment 9 of the present invention.
FIG. 11 is a time slot operation diagram in a conventional technique.
FIG. 12 is a block diagram showing a configuration of a wireless communication terminal according to a conventional technique.
[Explanation of symbols]
11 High frequency modem
12 Synchronization detector
13 Scheduling management unit
14 Transmission / reception control unit
15 Receive slot management unit
16 Window width calculator
17 Operation mode discriminator
18 Window parameter selection section
19 Time slot fluctuation amount calculation unit
20 Window width reference value calculation unit
21 Window width step value calculator
22 Time slot fluctuation amount holding unit
23 Window width reference value calculation unit
24 Reference value update control unit
25 Fluctuation calculation unit
26 Statistical value update control unit
27, 30 table update control unit
28 Correction calculation unit
29 Operation mode discriminator
100, 200, 300, 400, 500, 600, 700, 800, 900 wireless communication terminals
101 packets
102 Synchronization pattern
103 Synchronization window
S1 wireless signal
S2 Demodulated signal
S3 Synchronization window period information
S4 Synchronization pattern detection information
S5 reception control signal
S6 Control signal to high-frequency line demodulator
S7 Number of free slots
S8, S8a, S8b Reference value of synchronization window width
S9, S9a, S9b Step value of synchronous window width
S10 Synchronous window width
S11 Operation mode information
S12 Synchronization pattern detection predicted time
S13 Time slot fluctuation
S14 Correlation table correlation value
S15 Synchronous window width reference value
S17 Operation mode selection signal
S18 Fluctuation statistics

Claims (9)

High frequency modulation / demodulation means for performing modulation / demodulation processing of a radio signal;
Synchronization detection means for detecting a synchronization pattern from the demodulated signal by the high-frequency modulation and demodulation means based on the input synchronization window period information and outputting synchronization pattern detection information,
Receiving the synchronization pattern detection information from the synchronization detection means, determining whether the synchronization pattern has not been detected or completing packet reception, outputting a reception control signal to perform time management and timing correction of transmission / reception time slots, and Scheduling management means for outputting information to the synchronization detection means;
A radio communication terminal of a time slot synchronization method, comprising: a transmission / reception control unit that outputs a control signal for stopping a reception operation to the high-frequency modulation / demodulation unit based on the reception control signal from the scheduling management unit.
Receiving slot management means for managing the number of continuations of empty slots based on the synchronization pattern detection information by the synchronization detection means,
The reception slot management means calculates a synchronization window width based on the continuation number of empty slots and a reference value and a step value of the synchronization window width, and controls the scheduling management means for time management of the transmission / reception time slot and timing correction. Window width calculation means for outputting the synchronization window width for the
A wireless communication terminal, wherein the synchronization window width is varied according to a state of a reception slot. Further, an operation mode determining means for determining an operation mode at a prescribed timing,
A reference value and a step value of a synchronization window width for each operation mode, and selecting a reference value and a step value of the synchronization window width corresponding to the operation mode determined by the operation mode determination means; The wireless communication terminal according to claim 1, further comprising: a window parameter selection unit that outputs. Further, a time slot fluctuation amount calculating means for calculating a time slot fluctuation amount which is a time lag between a detection time of the synchronization pattern by the synchronization detecting means and a detection predicted time by the scheduling management means,
Window width reference value calculation for calculating a reference value of the synchronous window width for the window width calculation means based on the time slot fluctuation amount by the time slot fluctuation amount calculation means and the number of free slots continued by the reception slot management means The wireless communication terminal according to claim 1, further comprising: Further, a time slot fluctuation amount calculating means for calculating a time slot fluctuation amount which is a time lag between a detection time of the synchronization pattern by the synchronization detecting means and a detection predicted time by the scheduling management means,
Window width step value calculation for calculating a step value of the synchronous window width for the window width calculation means based on the time slot fluctuation amount by the time slot fluctuation amount calculation means and the continuation number of empty slots by the reception slot management means The wireless communication terminal according to claim 1, further comprising: Further, a time slot fluctuation amount calculating means for calculating a time slot fluctuation amount which is a time lag between a detection time of the synchronization pattern by the synchronization detecting means and a detection predicted time by the scheduling management means,
On the basis of the time slot fluctuation amount by the time slot fluctuation amount calculating means and the vacant slot continuation number by the reception slot managing means, the number of elapsed time slots after the time slot is corrected and the time slot fluctuation amount And a time slot variation holding means for holding the obtained correlation value in a correlation table,
The window width calculation means searches the time slot fluctuation amount holding means based on the number of continuations of the empty slots from the reception slot management means, and in the correlation table based on the number of elapsed time slots by the number of continuations of the empty slots. The wireless communication terminal according to claim 1, wherein the wireless communication terminal is configured to calculate the synchronization window width with reference to the correlation value. Further, a window width reference value calculation means for calculating a reference value of the synchronization window width based on the time slot change amount by the time slot change amount calculation means and the number of free slots continued by the reception slot management means,
The wireless communication terminal according to claim 5, further comprising: a reference value update control unit that controls registration of the reference value or its correction value to the time variation holding unit by the window width reference value calculation unit. Further, based on the time slot fluctuation amount by the time slot fluctuation amount calculation means and the empty slot continuation number by the reception slot management means, statistical calculation processing of the time slot fluctuation amount according to the empty slot continuation number is performed. Fluctuation amount calculation processing means,
6. The wireless communication terminal according to claim 5, further comprising: a statistic update control unit that controls registration of a calculation result of the change amount calculation processing unit in the time slot change amount holding unit. Further, an operation mode determining means for determining an operation mode at a prescribed timing,
Table update control means for restricting registration access to the time slot fluctuation amount holding means according to the operation mode by the operation mode determination means,
6. The wireless communication terminal according to claim 5, further comprising: a correction operation unit that corrects a correlation value referred to by the time slot variation holding unit according to the operation mode by the operation mode determination unit. A plurality of the time slot variation holding means are provided for each operation mode,
Further, an operation mode determining means for determining an operation mode at a prescribed timing,
The wireless communication terminal according to claim 5, further comprising: a table update control unit that selects one of the plurality of time slot fluctuation amount holding units according to an operation mode determined by the operation mode determination unit.

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