Receiving apparatus, and correction method

Abstract

To provide a receiving apparatus and a correction method to appropriately set a reception period in intermittent reception.SOLUTION: A wireless communication terminal 1 is a receiving apparatus of a TDMA system for performing intermittent reception by a reception period of a time slot and a non-reception period of a predetermined number of consecutive time slots which follow the reception period and in which reception is suspended. The receiving apparatus includes: a symbol clock controller configured to perform symbol synchronization at a synchronous word termination timing included in a time slot received for each base station in the reception period after the non-reception period, and to calculate frequency correction data of a symbol clock frequency on the basis of the number of time slots after a previous reception period and a symbol count value obtained by counting the number of symbols after that period; a memory configured to store the calculated frequency correction data for each base station; and a reception period controller configured to, when being reconnected to the base station stored in the memory, correct a reception termination timing of a time slot period on the basis of the frequency correction data of the reconnected base station.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a receiving apparatus and a correction method.

Background Art

[0002] In a wireless communication terminal that performs intermittent reception (hereinafter also referred to as a mobile station), a technique for synchronizing the symbol clock of the mobile station with the symbol clock of a base station is known. For example, Patent Document 1 discloses a technique for a mobile communication terminal that improves reception performance while suppressing power consumption during standby.

[0003]

[0004]

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technique of Patent Document 1, the length of the detection period of the unique word in the next slot is set due to a deviation in the timing of detecting the unique word. However, since the length of the reception period in the slot for detecting and correcting the synchronization deviation is not appropriate, there is a possibility that the data in the slot for detecting the synchronization deviation cannot be demodulated.

[0006] An object of the present invention is to provide a receiving apparatus and a correction method capable of making the reception period in intermittent reception appropriate.

Means for Solving the Problems

[0007] A receiving apparatus according to an aspect of the present invention performs intermittent reception by a reception period of time slots and a non-reception period for suspending reception of a predetermined number of consecutive time slots after the reception period. It is a receiving apparatus of a TDMA system that performs intermittent reception by a reception period of time slots and a non-reception period for suspending reception of a predetermined number of consecutive time slots after the reception period. In the reception period after the non-reception period, symbol synchronization is performed at the end timing of a synchronization word included in the received time slot for each base station. At the same time, based on the symbol count value obtained by counting the number of time slots and the number of symbols between them since the previous reception period, frequency correction data for each base station of the symbol clock frequency is calculated. A symbol clock control unit that calculates the frequency correction data for each base station of the symbol clock frequency, and for each base station, a memory that stores the frequency correction data calculated by the symbol clock control unit, and when reconnecting to the base station stored in the memory, based on the frequency correction data of the reconnected base station stored in the memory, a reception period control unit that corrects the end timing of reception of the time slot period in which the synchronization word included in the received time slot is detected. A symbol clock control unit that calculates the frequency correction data for each base station of the symbol clock frequency, and for each base station, a memory that stores the frequency correction data calculated by the symbol clock control unit, and when reconnecting to the base station stored in the memory, based on the frequency correction data of the reconnected base station stored in the memory, a reception period control unit that corrects the end timing of reception of the time slot period in which the synchronization word included in the received time slot is detected. A symbol clock control unit that calculates the frequency correction data for each base station of the symbol clock frequency, and for each base station, a memory that stores the frequency correction data calculated by the symbol clock control unit, and when reconnecting to the base station stored in the memory, based on the frequency correction data of the reconnected base station stored in the memory, a reception period control unit that corrects the end timing of reception of the time slot period in which the synchronization word included in the received time slot is detected. A symbol clock control unit that calculates the frequency correction data for each base station of the symbol clock frequency, and for each base station, a memory that stores the frequency correction data calculated by the symbol clock control unit, and when reconnecting to the base station stored in the memory, based on the frequency correction data of the reconnected base station stored in the memory, a reception period control unit that corrects the end timing of reception of the time slot period in which the synchronization word included in the received time slot is detected. A symbol clock control unit that calculates the frequency correction data for each base station of the symbol clock frequency, and for each base station, a memory that stores the frequency correction data calculated by the symbol clock control unit, and when reconnecting to the base station stored in the memory, based on the frequency correction data of the reconnected base station stored in the memory, a reception period control unit that corrects the end timing of reception of the time slot period in which the synchronization word included in the received time slot is detected. A symbol clock control unit that calculates the frequency correction data for each base station of the symbol clock frequency, and for each base station, a memory that stores the frequency correction data calculated by the symbol clock control unit, and when reconnecting to the base station stored in the memory, based on the frequency correction data of the reconnected base station stored in the memory, a reception period control unit that corrects the end timing of reception of the time slot period in which the synchronization word included in the received time slot is detected. It is provided with a reception period control unit that corrects the end timing of reception of the time slot period in which the synchronization word included in the received time slot is detected.

[0008] A correction method according to an aspect of the present invention is a correction method in a receiving apparatus of a TDMA system that performs intermittent reception by a reception period of time slots and a non-reception period for suspending reception of a predetermined number of consecutive time slots after the reception period. In the reception period after the non-reception period, symbol synchronization is performed at the end timing of a synchronization word included in the received time slot for each base station. At the same time, based on the symbol count value obtained by counting the number of time slots and the number of symbols between them since the previous reception period, frequency correction data for each base station of the symbol clock frequency is calculated. In the reception period after the non-reception period, symbol synchronization is performed at the end timing of a synchronization word included in the received time slot for each base station. At the same time, based on the symbol count value obtained by counting the number of time slots and the number of symbols between them since the previous reception period, frequency correction data for each base station of the symbol clock frequency is calculated. A step of calculating frequency correction data for each base station of the symbol clock frequency based on the symbol count value obtained by counting the number of time slots and the number of symbols between them since the previous reception period. For each base station, a step of calculating frequency correction data for each base station of the symbol clock frequency based on the symbol count value obtained by counting the number of time slots and the number of symbols between them since the previous reception period. A step of storing frequency correction data calculated by a control unit, and a base station stored in the memory When reconnecting to the station again, the frequency of the reconnected base station stored in the memory Based on the correction data, a step of detecting the synchronization word included in the received time slot and correcting the end timing of reception during the time slot period Including, a correction method.

Effect of the Invention

[0009] According to the present invention, the reception period in intermittent reception can be made appropriate.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited by this embodiment, and when there are a plurality of embodiments, those configured by combining each embodiment are also included. Further, in the following embodiments, the same parts are denoted by the same reference numerals to omit redundant explanations. form, and when there are a plurality of embodiments, those configured by combining each embodiment are also included. Further, in the following embodiments, the same parts are denoted by the same reference numerals to omit redundant explanations.

[0012] [Wireless Communication Terminal] The configuration of the wireless communication terminal according to the embodiment will be described with reference to FIG. 1. FIG. 1 is a block diagram showing an example of the configuration of a wireless communication terminal according to an embodiment. state is a block diagram showing an example of the configuration of a wireless communication terminal according to the embodiment.

[0013] As shown in FIG. 1, the wireless communication terminal 1 includes an antenna 10, an antenna switching unit 20, and a demodulation The circuit 30, the A / D converter 40, the D / A converter 50, the modulation circuit 60, and the control unit 70 are provided.

[0014] The wireless communication terminal 1 is a wireless communication terminal capable of intermittent reception operation. The wireless communication terminal 1 controls the antenna switching unit 20 to connect the antenna 10 to the modulation circuit 60 when transmitting a signal, turns on the power of the modulation circuit 60 and transmits the signal. When receiving a signal, the wireless communication terminal 1 controls the antenna switching unit 20 to connect the antenna 10 to the demodulation circuit 30, and turns on the power of the demodulation circuit 30 to receive the signal. Specifically, the wireless communication terminal 1 performs intermittent reception by a reception period of a time slot and a non-reception period in which reception of a predetermined number of consecutive time slots after the reception period is suspended, and has a function as a TDMA (Time Division Multiple Access) reception device. However, during the non-reception period of the intermittent reception operation, the wireless communication terminal 1 turns off the power of the demodulation circuit 30 to perform power saving operation. The antenna 10 transmits RF (Radio Frequency) to the base station. The antenna 10 receives the RF signal transmitted from the base station. The antenna switching unit 20 is controlled by the control unit 70. The antenna switching unit 20 connects the antenna 10 to either the demodulation circuit 30 or the modulation circuit 60 according to the control of the control unit 70.

[0015] The demodulation circuit 30 demodulates the RF signal received by the antenna switching unit 20 to generate an analog signal. The demodulation circuit 30 outputs the generated analog signal to the A / D converter 40. The demodulation circuit 30 outputs the generated analog signal to the A / D converter 40.

[0016] The antenna switching unit 20 is controlled by the control unit 70. The antenna switching unit 20 connects the antenna 10 to either the demodulation circuit 30 or the modulation circuit 60 according to the control of the control unit 70. The antenna switching unit 20 is controlled by the control unit 70. The antenna switching unit 20 connects the antenna 10 to either the demodulation circuit 30 or the modulation circuit 60 according to the control of the control

[0017] The demodulation circuit 30 demodulates the RF signal received by the antenna switching unit 20 to generate an analog signal. The demodulation circuit 30 outputs the generated analog signal to the A / D converter 40. The demodulation circuit 30 outputs the generated analog signal to the A / D converter 40. Oh, during the non-reception period when the wireless communication terminal 1 is in the intermittent reception operation, the demodulation circuit 30 is connected to the control unit 70 and the power is turned off, and it performs a power-saving operation. During the power-saving operation, the demodulation circuit 30 does not perform the demodulation of the RF signal.

[0018] The A / D converter 40 converts the analog signal input from the demodulation circuit 30 into a digital signal. The A / D converter 40 outputs the converted digital signal to the reception filter 71 of the control unit 70.

[0019] The D / A converter 50 converts the digital signal input from the transmission filter 79 of the control unit 70 into an analog signal. The D / A converter 50 outputs the converted analog signal to the modulation circuit 60.

[0020] The modulation circuit 60 modulates the analog signal input from the D / A converter 50 to generate an RF signal. The modulation circuit 60 outputs the generated analog signal to the antenna 10.

[0021] The control unit 70 is realized, for example, by a CPU (Central Processing Unit), an MPU (Micro Processing Unit), etc., when a program stored in a storage unit (not shown) is executed in a work area such as a RAM. That is, the control unit 70 realizes each function of the wireless communication terminal 1 in this embodiment by executing a program recorded on a computer-readable non-temporary recording medium. The control unit 70 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The control unit 70 is composed of hardware and software. ​ It may be realized in combination with A.

[0022] The control unit 70 includes a reception filter 71, a symbol detection unit 72, an FEC (Forward Error Correction) decoder unit 73, a synchronization word detection unit 74, a symbol clock control unit 7 5, a reception period control unit 76, an FEC encoder unit 77, a symbol generation unit 78, and a transmission filter 79. The control unit 70 has a function of controlling each part of the wireless communication terminal 1.

[0023] The reception filter 71 removes signal components in unnecessary bands included in the digital signal input from the A / D converter 40. The reception filter 71 outputs the digital signal from which the signal components in the unnecessary bands have been removed to the symbol detection unit 72 and the synchronization word detection unit 74. The band removed by the reception filter 71 can be arbitrarily set.

[0024] The symbol detection unit 72 determines the symbol value of the digital signal input from the reception filter 71 according to the control of the symbol clock control unit 75. Specifically, the symbol detection unit 72 determines the symbol value at the timing of the symbol clock input from the symbol clock control unit 75. The symbol detection unit 72 outputs data regarding the symbol value obtained as a result of the determination to the FEC decoder unit 73.

[0025] The FEC decoder unit 73 performs FEC decoding processing on the data regarding the symbol value input from the symbol detection unit 72.

[0026] The synchronization word detection unit 74 detects a synchronization word from the digital signal input from the reception filter 71. ​​​​​​​​​Detect the synchronization word. When the synchronization word is detected by the synchronization word detection unit 74, the symbol clock outputs a timing signal regarding the timing at which the synchronization word is detected to the lock control unit 75. Output.

[0027] When the wireless communication terminal 1 receives an RF signal, the symbol clock control unit 75 outputs a symbol clock to the symbol detection unit 72. When the wireless communication terminal 1 transmits an RF signal, the symbol clock control unit 75 outputs a symbol clock to the symbol generation unit 78. The symbol clock control unit 75 incorporates a symbol counter that counts for each symbol clock. The symbol clock control unit 75 measures the number of symbols from when the count of the symbol clock was last reset to the present by the symbol counter, and derives a symbol count value. When a timing signal is input from the synchronization word detection unit 74 when the wireless communication terminal 1 receives an RF signal, the symbol clock control unit 75 resets the output timing of the symbol clock and the symbol counter based on the timing signal. Outputs a symbol clock to the symbol detection unit 72. When the wireless communication terminal 1 transmits an RF signal, the symbol clock control unit 75 outputs a symbol clock to the symbol generation unit 78. The symbol clock control unit 75 incorporates a symbol counter that counts for each symbol clock. The symbol clock control unit 75 measures the number of symbols from when the count of the symbol clock was last reset to the present by the symbol counter, and derives a symbol count value. When a timing signal is input from the synchronization word detection unit 74 when the wireless communication terminal 1 receives an RF signal, the symbol clock control unit 75 resets the output timing of the symbol clock and the symbol counter based on the timing signal. Outputs a symbol clock to the symbol generation unit 78. The symbol clock control unit 75 incorporates a symbol counter that counts for each symbol clock. The symbol clock control unit 75 measures the number of symbols from when the count of the symbol clock was last reset to the present by the symbol counter, and derives a symbol count value. When a timing signal is input from the synchronization word detection unit 74 when the wireless communication terminal 1 receives an RF signal, the symbol clock control unit 75 resets the output timing of the symbol clock and the symbol counter based on the timing signal. Outputs a symbol clock to the symbol generation unit 78. The symbol clock control unit 75 incorporates a symbol counter that counts for each symbol clock. The symbol clock control unit 75 measures the number of symbols from when the count of the symbol clock was last reset to the present by the symbol counter, and derives a symbol count value. When a timing signal is input from the synchronization word detection unit 74 when the wireless communication terminal 1 receives an RF signal, the symbol clock control unit 75 resets the output timing of the symbol clock and the symbol counter based on the timing signal. Incorporates a symbol counter that counts for each symbol clock. The symbol clock control unit 75 measures the number of symbols from when the count of the symbol clock was last reset to the present by the symbol counter, and derives a symbol count value. When a timing signal is input from the synchronization word detection unit 74 when the wireless communication terminal 1 receives an RF signal, the symbol clock control unit 75 resets the output timing of the symbol clock and the symbol counter based on the timing signal. Measures the number of symbols from when the count of the symbol clock was last reset to the present by the symbol counter, and derives a symbol count value. When a timing signal is input from the synchronization word detection unit 74 when the wireless communication terminal 1 receives an RF signal, the symbol clock control unit 75 resets the output timing of the symbol clock and the symbol counter based on the timing signal. Derives a symbol count value. When a timing signal is input from the synchronization word detection unit 74 when the wireless communication terminal 1 receives an RF signal, the symbol clock control unit 75 resets the output timing of the symbol clock and the symbol counter based on the timing signal. When a timing signal is input from the synchronization word detection unit 74 when the wireless communication terminal 1 receives an RF signal, the symbol clock control unit 75 resets the output timing of the symbol clock and the symbol counter based on the timing signal. Based on the timing signal, the output timing of the symbol clock and the symbol counter are reset. Reset.

[0028] When the symbol clock control unit 75 resets the output timing of the symbol clock and the symbol counter, it refers to the symbol count value at this time to calculate the difference in the symbol clock between the wireless communication terminal 1 and the base station. The symbol clock control unit 75 corrects the symbol clock frequency fc of the wireless communication terminal 1 based on the calculated difference in the symbol clock and the number of time slots from the last time slot when the synchronization word was detected. The method of correcting the symbol clock frequency fc will be described later. The symbol clock Refers to the symbol count value at this time to calculate the difference in the symbol clock between the wireless communication terminal 1 and the base station. The symbol clock control unit 75 corrects the symbol clock frequency fc of the wireless communication terminal 1 based on the calculated difference in the symbol clock and the number of time slots from the last time slot when the synchronization word was detected. The method of correcting the symbol clock frequency fc will be described later. The symbol clock Calculates the difference in the symbol clock between the wireless communication terminal 1 and the base station. The symbol clock control unit 75 corrects the symbol clock frequency fc of the wireless communication terminal 1 based on the calculated difference in the symbol clock and the number of time slots from the last time slot when the synchronization word was detected. The method of correcting the symbol clock frequency fc will be described later. The symbol clock Based on the calculated difference in the symbol clock and the number of time slots from the last time slot when the synchronization word was detected, corrects the symbol clock frequency fc of the wireless communication terminal 1. The method of correcting the symbol clock frequency fc will be described later. The symbol clock Based on the calculated difference in the symbol clock and the number of time slots from the last time slot when the synchronization word was detected, corrects the symbol clock frequency fc of the wireless communication terminal 1. The method of correcting the symbol clock frequency fc will be described later. The symbol clock Corrects. The method of correcting the symbol clock frequency fc will be described later. The symbol clock The lock control unit 75 outputs frequency correction data regarding the correction result of the symbol clock frequency to the reception period control unit 76.

[0029] After the synchronization word is detected by the synchronization word detection unit 74, the reception period control unit 76 corrects the end timing of the reception in the time slot period in which the synchronization word is detected based on the frequency correction data input from the lock control unit 75. A method for correcting the end timing of the reception in the time slot period in which the synchronization word is detected will be described later. The reception period control unit 76 outputs timing correction data regarding the corrected end timing to the FEC decoding unit 73.

[0030] The FEC encoding unit 77 performs FEC encoding processing on the transmission data to be transmitted to the base station. The FEC encoding unit 77 outputs the FEC-encoded transmission data to the symbol generation unit 78.

[0031] The symbol generation unit 78 converts the FEC-encoded transmission data input from the FEC encoding unit 77 into symbol values. The symbol generation unit 78 outputs a signal regarding the symbol values at the timing of the symbol clock input from the symbol clock control unit 75 to the transmission filter 79.

[0032] The transmission filter 79 removes signal components in unnecessary bands included in the signal regarding the symbol values input from the symbol generation unit 78. The transmission filter 79 outputs the signal from which the signal components in the unnecessary bands have been removed to the D / A converter 50. The band removed by the transmission filter 79 is arbitrarily settable.

[0033] ​​​​​​​​​​[Correction Process of Symbol Clock Frequency] With reference to FIG. 2, the process of correcting the symbol clock frequency fc according to the embodiment will be described. FIG. 2 is a timing chart for explaining a method of correcting the symbol clock frequency fc. It is a timing chart.

[0034] In the timing chart shown in FIG. 2, the transmission timing of the base station, the reception timing of the wireless communication terminal 1, the intermittent reception cycle of the wireless communication terminal 1, the symbol clock of the base station, and the symbol clock of the wireless communication terminal 1 are shown. The intermittent reception cycle of the wireless communication terminal 1, the symbol clock of the base station, and the symbol clock of the wireless communication terminal 1 are shown. It is shown.

[0035] Period T1 indicates the non-reception period in the intermittent reception operation of the wireless communication terminal 1 existing within the base station area. During period T1, the wireless communication terminal 1 turns off the power of the demodulation circuit 30 to perform a power-saving operation. During period T1, the symbol clock of the base station and the symbol clock of the wireless communication terminal 1 are not synchronized. Period T1 indicates the non-reception period in the intermittent reception operation of the wireless communication terminal 1 existing within the base station area. During period T1, the wireless communication terminal 1 turns off the power of the demodulation circuit 30 to perform a power-saving operation. During period T1, the symbol clock of the base station and the symbol clock of the wireless communication terminal 1 are not synchronized. It is not synchronized.

[0036] Time point t1 indicates the timing at which the non-reception period of the intermittent reception of the wireless communication terminal 1 ends and the reception period starts. At the timing of time point t1, the wireless communication terminal 1 turns on the power of the demodulation circuit 30 to make it possible to demodulate the received signal. From time point t1 until the timing at which the reception period ends, the symbol detection unit 72 outputs data of one symbol for each symbol clock input from the symbol clock control unit 75. The FEC decoding unit 73 executes FEC decoding processing on the input data when a predetermined number of symbols are input. At the timing of time point t1, the wireless communication terminal 1 turns on the power of the demodulation circuit 30 to make it possible to demodulate the received signal. From time point t1 until the timing at which the reception period ends, the symbol detection unit 72 outputs data of one symbol for each symbol clock input from the symbol clock control unit 75. The FEC decoding unit 73 executes FEC decoding processing on the input data when a predetermined number of symbols are input. For each symbol clock input from the symbol clock control unit 75, the symbol detection unit 72 outputs data of one symbol. When a predetermined number of symbols are input, the FEC decoding unit 73 executes FEC decoding processing on the input data.

[0037] Time point t2 indicates the timing at which the wireless communication terminal 1 receives the last symbol of the synchronization word. At time point t2, the transmission slot 80, which is a time slot on the base station side, and the wireless communication ... The timing is consistent with that of reception slot 90, which is a time slot of the communication terminal 1. Therefore, at time point t2, the timing at which the wireless communication terminal 1 receives the last symbol of the synchronization word 81 is consistent with the timing at which the base station transmits the last symbol of the synchronization word 81. Here, the synchronization word detection unit 74 outputs a timing signal regarding the timing of detection of the synchronization word to the symbol clock control unit 75. The symbol clock control unit 75, according to the timing signal input from the synchronization word detection unit 74, resets the output timing of the symbol clock of the wireless communication terminal 1 and the symbol counter. In the present embodiment, the process of resetting the output timing of the symbol clock and the symbol counter is sometimes also called symbol synchronization. At this moment, the symbol clocks of the base station and the wireless communication terminal 1 are consistent.

[0038] Time point t3 indicates the timing at which the reception period of the intermittent reception of the wireless communication terminal 1 ends and the non-reception period starts. At the timing of time point t3, the wireless communication terminal 1 turns off the power supply of the demodulation circuit 30 and starts power-saving operation.

[0039] Time point t4 indicates the timing at which the reception period of the intermittent reception of the wireless communication terminal 1 ends and the reception period starts again. At the timing of time point t4, the wireless communication terminal 1 turns on the power supply of the demodulation circuit 30 to make it possible to demodulate the received signal. That is, in the example shown in FIG. 2, there are 4 reception slots 90 in one cycle. From time point t4 until the timing at which the reception period ends, the symbol detection unit 72 outputs data of one symbol for each symbol clock input from the symbol clock control unit 75. However, the wireless communication terminal 1 symbol clock Started the reception interval based on the symbol clock from the oscillator inside the lock control unit 75 As a result, the timing between the received slot and the transmission slot of the base station is shifted. Therefore , the symbol detection unit 72 cannot output the desired result.

[0040] Time point t5 indicates the timing when the wireless communication terminal 1 receives the last symbol of the synchronization word However, since the timing between the transmission slot 80 of the base station and the reception slot 9 0 of the wireless communication terminal 1 is shifted, the timing when the wireless communication terminal 1 receives the last symbol of the synchronization word 81 is also shifted from the timing when the transmitting station transmits the last symbol of the synchronization word 81. Therefore, at time point t5, the synchronization word detection unit 74 does not output a timing signal indicating the timing for detecting the synchronization word.

[0041] Time point t6 indicates the timing when the base station transmits the last symbol of the synchronization word. At the timing of time point t6, the synchronization word detection unit 74 detects the synchronization word and outputs a timing signal to the symbol clock control unit 75. Then, the symbol clock control unit 75 performs the reset of the output timing of the symbol clock of the wireless communication terminal 1 and the symbol counter in the same manner as at time point t2.

[0042] At time point t6, the symbol clock control unit 75 corrects the symbol clock frequency of the wireless communication terminal 1. Specifically, the symbol clock control unit 75 refers to the count value of the symbol number at time point t6 to calculate the difference in the symbol number between the wireless communication terminal 1 and the base station, and the result of the calculated difference and the time slot when the synchronization word was last detected Based on the number of time slots from the slot [SLOT], the symbol clock frequency is corrected. For example , in the communication format shown in FIG. 2, the number of symbols in one time slot is set to 10 . As in the example shown in FIG. 2, at the moment when the synchronization word is detected in a 4-slot period, the symbol counter of the symbol clock control unit 75 should originally be 40.

[0043] Here, it is assumed that the symbol detection unit 72 detected that the number of symbols for 4 slots is 41. This means that the symbol clock in one cycle of the wireless communication terminal 1 is one symbol faster than the symbol clock of the base station, that is, the symbol clock frequency fc is high. Based on this difference value, the symbol clock control unit 75 corrects the symbol clock frequency. In this case, the symbol clock control unit 75 sets the symbol clock frequency so as to delay the number of symbol clocks in one cycle by one symbol. That is, the symbol clock frequency fc is set to (symbol clock frequency before correction × (number of symbol clocks in one cycle - difference in the number of symbol clocks) ÷ number of symbol clocks in one cycle). Thereby, the symbol clock frequency fc of the wireless communication terminal 1 can be synchronized with the symbol clock frequency of the base station. Note that in the example shown in FIG. 2, for simplicity of explanation, it was described that the number of symbols included in one time slot is 10, but this is an example and does not limit the present invention. The number of symbols included in one time slot can be arbitrary. .

[0044] At time t7, it shows the timing when the reception interval of the intermittent reception of the wireless communication terminal 1 ends and the non-reception interval starts. At the timing of time t7, the wireless communication terminal 1 is at the demodulation circuit 30 Turn off the power to start the power-saving operation. Also, the number of symbol clocks from the end timing of the synchronization word to the end timing of the reception slot is known. At the timing of time point t7, the symbol clock frequency fc of the wireless communication terminal 1 is synchronized with the symbol clock frequency of the base station. This is because after detecting the synchronization word, the reception period control unit 76 corrects the end timing of the reception of the reception slot 90 detected based on the symbol clock corrected by the symbol clock control unit 75. Therefore, the timing at which the wireless communication terminal 1 receives the last symbol of the synchronization word 81 coincides with the timing at which the transmitting station transmits the last symbol of the synchronization word 81. As a result, after time point t7, the frequencies of the symbol clock of the base station and the wireless communication terminal 1 are synchronized. In other words, the reception period control unit 76 corrects the reception start timing and the reception end timing after the reception slot 90 in which the synchronization word is detected. The number of symbol clocks from the end timing of the synchronization word to the end timing of the reception slot is known. At the timing of time point t7, the symbol clock frequency fc of the wireless communication terminal 1 is synchronized with the symbol clock frequency of the base station. This is because after detecting the synchronization word, the reception period control unit 76 corrects the end timing of the reception of the reception slot 90 detected based on the symbol clock corrected by the symbol clock control unit 75. Therefore, the timing at which the wireless communication terminal 1 receives the last symbol of the synchronization word 81 coincides with the timing at which the transmitting station transmits the last symbol of the synchronization word 81. As a result, after time point t7, the frequencies of the symbol clock of the base station and the wireless communication terminal 1 are synchronized. In other words, the reception period control unit 76 corrects the reception start timing and the reception end timing after the reception slot 90 in which the synchronization word is detected. Time point t8 indicates the timing when the reception period of the intermittent reception of the wireless communication terminal 1 ends and the reception period starts again. At the timing of time point t8, the wireless communication terminal 1 turns on the power of the demodulation circuit 30 to make it possible to demodulate the received signal. At the timing of time point t8, the symbol clock frequency of the wireless communication terminal 1 is synchronized with the symbol clock frequency of the base station. Therefore, the timing at which the wireless communication terminal 1 receives the first symbol of the synchronization word 81 coincides with the timing at which the transmitting station transmits the first symbol of the synchronization word 81. That is, the transition timing from the non-reception period to the reception period of the intermittent reception of the wireless communication terminal 1 coincides with the timing at which the base station transmits the first symbol of the transmission slot.

[0045] Time point t8 indicates the timing when the reception period of the intermittent reception of the wireless communication terminal 1 ends and the reception period starts again. At the timing of time point t8, the wireless communication terminal 1 turns on the power of the demodulation circuit 30 to make it possible to demodulate the received signal. At the timing of time point t8, the symbol clock frequency of the wireless communication terminal 1 is synchronized with the symbol clock frequency of the base station. Therefore, the timing at which the wireless communication terminal 1 receives the first symbol of the synchronization word 81 coincides with the timing at which the transmitting station transmits the first symbol of the synchronization word 81. That is, the transition timing from the non-reception period to the reception period of the intermittent reception of the wireless communication terminal 1 coincides with the timing at which the base station transmits the first symbol of the transmission slot. At the timing of time point t8, the wireless communication terminal 1 turns on the power of the demodulation circuit 30 to make it possible to demodulate the received signal. At the timing of time point t8, the symbol clock frequency of the wireless communication terminal 1 is synchronized with the symbol clock frequency of the base station. That is, the transition timing from the non-reception period to the reception period of the intermittent reception of the wireless communication terminal 1 coincides with the timing at which the base station transmits the first symbol of the transmission slot.

[0046] In this embodiment, the symbol clock frequency of the wireless communication terminal 1 before correction is the basic It is preferable that the frequency is set higher than the symbol clock frequency of the base station. For example, as shown at time t4, the head of the reception slot of the wireless communication terminal 1 is the base station The position of the transmission slot is located before the beginning of the corresponding transmission slot of the wireless communication terminal 1. , the first symbol of the sync word 81 can be received, so that the symbol The clock frequency can be corrected.

[0047] As described above, in this embodiment, the symbol clock frequency of the base station and the The symbol clock frequency is synchronized between the wireless communication terminals 1 in this embodiment. The timing of the transition from a non-receiving section to a receiving section and the timing when the base station As a result, in this embodiment, the timing of the reception period in the intermittent reception is can be made appropriate.

[0048] In this embodiment, the symbol clock frequency of the base station and the symbol clock frequency of the wireless communication terminal 1 are In order to synchronize the clock frequency, it is not necessary to turn on the wireless communication terminal 1 early. In this embodiment, at the moment when the non-reception period is changed to the reception period, the transmission signal transmitted from the base station is Then, reception of the first symbol of the communication slot is started. This allows the terminal 1 to operate in low power mode for a longer period of time, thereby reducing power consumption. can.

[0049] [Variations] Next, a modification of this embodiment will be described.

[0050] In this embodiment, the symbol clock control unit 75 corrects the symbol clock frequency based on the difference between the set number of symbols and the measured number of symbols in one reception interval between two points. However, the present invention is not limited to this. The symbol clock control unit 75 may set the symbol clock frequency as (symbol clock frequency before correction × symbol count number ÷ number of symbol clocks in one cycle). Also, when the difference in the number of symbols is extremely small after correction of the symbol clock, etc., the reception interval for correction may be extended, for example, from the current 4 time slots to 8 slots, which is twice as many, until the next correction is performed, and the symbol clock frequency may be corrected . Each time the wireless communication terminal 1 is powered on, the symbol clock frequency may be corrected as described above, or once the correction is performed, the correction value may be stored in the internal memory of the wireless communication terminal 1 and used for correction after the second correction. Specifically, after the correction is performed once, when the wireless communication terminal 1 is powered on, the symbol clock control unit 7 5 may read the correction value stored in the memory and correct the symbol clock frequency

[0051] . That is, the wireless communication terminal 1 may start receiving signals from the base station with the symbol clock frequency corrected . In this embodiment, the base station has been described as one, but this embodiment can also be applied to a wireless communication system having a plurality of base stations . For example, in a wireless communication system having a plurality of base stations, if the symbol clock frequencies between the base stations are not synchronized . .

[0052] In this embodiment, the base station has been described as one, but this embodiment can also be applied to a wireless communication system having a plurality of base stations. For example, in a wireless communication system having a plurality of base stations in which the symbol clock frequencies between the base stations are not synchronized . ​In this case, when the wireless communication terminal 1 moves from one base station to another, the method according to the embodiment The symbol clock frequency may be corrected again by the same method. The correction value is stored in the internal memory of the wireless communication terminal 1 for each base station, and the second correction is performed thereafter. Then, after the correction is performed once, the wireless communication terminal 1 When the power is turned on, the symbol clock control unit 75 receives the symbol clock for each base station stored in the memory. The correction value of the symbol clock frequency may be read out to correct the symbol clock frequency.

[0053] Although the embodiments of the present invention have been described above, the present invention is not limited to the contents of these embodiments. In addition, the above-mentioned components are not those that a person skilled in the art can easily imagine, and are not substantially different from the above-mentioned components. In addition, the above-mentioned components are appropriately Furthermore, the above-described embodiments may be combined without departing from the spirit of the present invention. Various omissions, substitutions or modifications of components may be made. [Explanation of symbols]

[0054] 1. Wireless communication terminal 10 Antennas 20 Antenna switching unit 30 Demodulation circuit 40 A / D Converter 50 D / A Converter 60 Modulation Circuit 70 Control section 71 Receiving Filter 72 Symbol detection unit 73 FEC Decoder 74 Sync word detector 75 Symbol clock control section 76 Reception period control section 77 FEC Encoding Section 78 Symbol Generation Unit 79 Transmission filter

Claims

1. A TDMA system receiver that performs intermittent reception based on a reception period for time slots and a non-reception period during which reception of a predetermined number of consecutive time slots after the reception period is suspended, wherein in the reception period after the non-reception period, symbol synchronization is performed at the end timing of a synchronization word included in a time slot received from a base station, and based on a symbol count value obtained by counting the number of time slots and the number of symbols between them since the previous reception period, a symbol clock control unit that calculates frequency correction data for the symbol clock frequency; a memory that stores the frequency correction data calculated by the symbol clock control unit for each base station; and a reception period control unit that corrects the end timing of reception during a time slot period in which the synchronization word in the reception period is detected based on the frequency correction data stored in the memory when reconnecting to the base station again after power is turned on. A receiver comprising the above components.

2. A correction method for a TDMA system receiver that performs intermittent reception based on a reception period for time slots and a non-reception period during which reception of a predetermined number of consecutive time slots after the reception period is suspended, the method comprising: in the reception period after the non-reception period, performing symbol synchronization at the end timing of a synchronization word included in a time slot received from a base station, and calculating frequency correction data for the symbol clock frequency based on a symbol count value obtained by counting the number of time slots and the number of symbols between them since the previous reception period; storing the calculated frequency correction data for each base station; and correcting the end timing of reception during a time slot period in which the synchronization word in the reception period is detected based on the frequency correction data of the base station when reconnecting to the base station again after power is turned on. A correction method including the above steps. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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