JP2006237936A - Timing synchronizing method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a timing synchronizing technique of improving detection accuracy suppressing an increase in throughput. <P>SOLUTION: A processing unit 22 receives signals continuously without carrying out adaptive array signal processing. A synchronizing unit 28 detects control signals sent from, at least, a base station device in the received signals. The synchronizing unit 28 specifies the timing of the detected control signals. The processing unit 22 carries out adaptive array signal processing and receives the signals intermittently based on the timing specified by the synchronizing unit 28. The synchronizing unit 28 detects the control signals sent from, at least, a certain base station device in the signals that are intermittently received. The synchronizing unit 28 specifies timing of, at least, one of the detected signals. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a timing synchronization technique, and more particularly to a timing synchronization method and apparatus for detecting the timing of a received signal.

In TDMA (Time Division Multiple Access) communication or the like, digital information is generally transmitted using a plurality of time slots that divide one frame. The establishment of timing synchronization between the transmitting apparatus and the receiving apparatus of TDMA communication is realized by detecting a unique word included in the transmitted time slot in the receiving apparatus. Even a terminal device of a mobile communication system such as a mobile phone system or a second generation cordless phone system detects a unique word transmitted from a base station device. In these systems, intermittent reception may be performed during non-communication in order to reduce power consumption. Further, in order to reduce power consumption, a high-speed and high-accuracy reference oscillator and a low-speed reference oscillator are provided, and a signal received by the high-speed and high-accuracy reference oscillator is sampled when communication processing is executed. On the other hand, at the time of standby processing, a signal received by a low-speed reference oscillator is sampled (see, for example, Patent Document 1).
JP-A-8-307304

  Immediately after the terminal device of the mobile communication system is activated, the terminal device performs the above-described unique word detection in order to establish timing synchronization with the base station device. At that time, since the terminal device cannot predict the timing at which the signal should arrive, it continuously receives the signal. Further, the terminal device performs unique word detection on the continuously received signal (hereinafter, such unique word detection is referred to as “open search”). Since the open search is executed continuously, the processing amount of the open search generally increases to some extent. Also, if adaptive array signal processing is applied to the terminal device, the signal reception characteristics at the terminal device are improved as compared with the case where adaptive array signal processing is not applied. On the other hand, the processing amount of weight vector derivation in adaptive array signal processing generally increases to some extent. If an open search is executed while adaptive array signal processing is being executed, the detection accuracy of the unique word is improved. However, the processing amount becomes large.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a timing synchronization technique that improves detection accuracy while suppressing an increase in processing amount.

  In order to solve the above-described problem, a timing synchronization apparatus according to an aspect of the present invention includes: a reception unit that receives a signal without performing adaptive array signal processing; and at least one base station from a signal received by the reception unit A signal detection unit for detecting a signal from the apparatus and a specifying unit for specifying the timing of the signal detected by the signal detection unit are provided. In the receiving unit, when the timing is specified by the specifying unit, execution of adaptive array signal processing is started in a period based on the specified timing, and the signal detecting unit is configured to perform adaptive array signal processing in the receiving unit. The signal from at least one base station apparatus is detected from the received signal, and the specifying unit specifies the timing again for at least one of the signals detected by the signal detecting unit.

  According to this aspect, as the first stage, the adaptive array signal processing is not performed, but the timing is specified from the continuously received signal, and as the second stage, the adaptive stage is used based on the timing specified in the first stage. Since the timing is specified from the intermittently received signal while executing the array signal processing, the adaptive array signal processing can be executed while shifting the timing from the detection of the continuous signal. Therefore, it is possible to improve detection accuracy while suppressing an increase in processing amount.

  The signal from the base station apparatus is assigned to one of a plurality of time slots that constitute a frame, and the specifying unit may specify the timing for each of the plurality of time slots. In this case, even when a time slot is used for communication, the timing of the time slot is specified, so that communication can be executed. Further, in the second generation cordless telephone system, a plurality of base station apparatuses are frame-synchronized, and the timing of each time slot is almost synchronized. Therefore, by specifying the timing of at least one time slot, communication can be performed. Can be executed.

  The period during which the adaptive array signal processing is to be executed in the receiving unit may be the head portion of the time slot. In this case, since reception is not performed at a timing that is separated from the timing of the specified time slot by a factor corresponding to a frame synchronization error, clock accuracy, transmission timing accuracy, propagation delay, and the like, the amount of processing increases. Can be suppressed. Further, since the adaptive array signal processing is not executed except for the head portion of the time slot, an increase in the processing amount can be suppressed.

  When the signal detection unit detects a signal from at least one base station device, the signal detection unit also detects the identification number of the base station device included in the detected signal, and the specifying unit detects the signal detected by the signal detection unit. When the timing is specified again for at least one of them, the base station apparatus corresponding to the timing may be specified using the identification number of the base station apparatus. In this case, the base station apparatus corresponding to the timing can be specified while specifying the timing. In addition, when detecting a signal from at least one base station device, the signal detection unit measures the signal strength for the detected signal, and the specifying unit specifies the base station device based on the measured signal strength. May be.

  You may further provide the determination part which determines communication with the base station apparatus specified in the specific part. In this case, it is possible to proceed to the communication stage after establishing the timing synchronization.

  The signal detection unit may include a storage unit that stores the signal received by the reception unit, and a unique word detection unit that detects a unique word from the signal stored in the storage unit. The storage unit has a storage area capable of storing a signal included in at least one time slot, stores the received signal in the storage area while cyclically overwriting the signal, and the unique word detection unit stores A unique word may be detected using the data amount of a signal included in one area when the area is divided into a plurality of areas as one detection unit. In this case, even if the storage capacity of the storage area is small, the unique word detection unit is even smaller than the storage capacity. Therefore, the unique word detection process can be executed at high speed, and the detection accuracy of the unique word is reduced while reducing the storage capacity. Can be prevented.

  The storage capacity of the storage area possessed by the storage unit may be the data amount of the signal included in one time slot. The “substantially one slot” includes not only the data amount of one time slot but also the data amount obtained by adding the data amount considering processing delay to the data amount of one time slot. In this case, since the data amount of the signal included in substantially one time slot is used as a unit, the processing can be simplified.

  Another aspect of the present invention is a timing synchronization method. This method is a timing synchronization method for detecting a signal from at least one base station apparatus from a signal received without performing adaptive array signal processing, and specifying the timing of the detected signal, and the timing is specified. Then, in the period based on the specified timing, the execution of adaptive array signal processing is started, the signal from at least one base station apparatus is detected, and at least one of the detected signals is detected. To identify the timing again

  Another aspect of the present invention is also a timing synchronization method. The method includes a step of receiving a signal without performing adaptive array signal processing, and a step of identifying a timing of the detected signal while detecting a signal from at least one base station apparatus from the received signal. When the timing is specified, a step of starting execution of adaptive array signal processing in a period based on the specified timing, and a signal from at least one base station apparatus from the signal subjected to adaptive array signal processing Re-specifying timing for at least one of the detected signals while detecting.

  The signal from the base station apparatus is assigned to one of a plurality of time slots that constitute a frame, and the step of specifying the timing of the detected signal is performed even if the timing for each of the plurality of time slots is specified. Good. The period during which adaptive array signal processing is to be executed in the step of starting execution of adaptive array signal processing may be at the beginning of a time slot. The step of identifying the timing of the detected signal is a step of detecting the identification number of the base station device included in the detected signal and detecting the timing again when detecting a signal from at least one base station device. May specify the base station apparatus corresponding to the timing while using the identification number of the base station apparatus.

  You may further comprise the step which determines communication with the base station apparatus specified in the step which specifies a timing again. The step of identifying the timing of the detected signal includes a step of storing the received signal in a memory and a step of detecting a unique word from the signal stored in the memory, and the step of storing includes at least one time slot. The step of storing the received signal in the memory area while cyclically overwriting the received signal in a memory having a storage area capable of storing the included signal, and detecting the unique word is made up of a plurality of areas. A unique word may be detected using the data amount of a signal included in one area when divided as one detection unit. The storage capacity of the storage area of the memory in the storing step may be the amount of signal data included in one time slot.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

  According to the present invention, it is possible to improve detection accuracy while suppressing an increase in processing amount.

Example 1
Before describing the present invention in detail, an outline will be described. The first embodiment of the present invention corresponds to a terminal device of a second generation cordless telephone system. The terminal device performs an open search in order to establish timing synchronization with the base station device. In addition, the terminal device includes a plurality of antennas, and performs adaptive array signal processing with the plurality of antennas. The terminal device according to the present embodiment operates as follows in order to suppress an increase in processing amount due to open search and adaptive array signal processing. The terminal device performs open search while enabling one of the plurality of antennas, that is, while realizing omnidirectional antenna characteristics. If signals from predetermined base station apparatuses are received by open search, the terminal apparatus specifies the timing for these signals.

  The terminal device sets a synchronization window from the specified timing, and receives a signal while executing adaptive array signal processing during the set synchronization window (hereinafter referred to as “array search”). If a signal from a predetermined base station apparatus is received by the array search, the terminal apparatus specifies the timing for one of the signals. Moreover, communication with the base station apparatus corresponding to the specified timing is determined. In general, the open search period is defined as a predetermined value (hereinafter referred to as “first period”). Therefore, the terminal device defines a period shorter than the first period (hereinafter referred to as “second period”), and the terminal apparatus performs an open search in the period equal to or less than the second period. As a result, the terminal device ends the open search and the array search during the first period. Thus, since the open search and the array search are executed during the open search period defined in the communication system, the detection accuracy can be improved while suppressing an increase in the processing amount.

  FIG. 1 illustrates a configuration of a communication system 100 according to the first embodiment. The communication system 100 includes a terminal device 10, a first base station device 14a, a second base station device 14b, a third base station device 14c, and a fourth base station device 14d, which are collectively referred to as a base station device 14. The terminal device 10 includes a first antenna 12a, a second antenna 12b, and a fourth antenna 12d, which are collectively referred to as the antenna 12.

  The terminal device 10 synchronizes with the timing of the base station device 14 in order to communicate with any one of the plurality of base station devices 14 or with two or more base station devices 14. However, since the terminal device 10 has not established timing synchronization with any of the base station devices 14 in the initial state, the above-described open search is executed. Here, in order to clarify the explanation, it is assumed that the terminal apparatus 10 communicates with any one of the plurality of base station apparatuses 14. As a premise, it is assumed that the signal from the base station apparatus 14 is assigned to one of a plurality of time slots (hereinafter referred to as “slots”) that constitute a frame. In addition, it is assumed that frame synchronization is established among the plurality of base station apparatuses 14.

  FIGS. 2A to 2B show a frame configuration and a slot configuration. FIG. 2A shows a frame configuration of the second generation cordless telephone system, and one frame includes eight slots. Of the eight slots, slots 1 to 4 are used as downlink signals, while slots 5 to 8 are used as uplink signals. Here, out of slot 1 to slot 4 of the downlink, slot 1 transmits a control signal. FIG. 2B shows the configuration of the slot 1. Here, “R” indicates a ramp bit, “SS” indicates a start symbol, “PR” indicates a preamble, “UW” indicates a unique word, “CAC” indicates a control signal, and “CRC” Indicates a CRC code, and “G” indicates a guard bit.

  Note that the numbers described below these symbols indicate the number of bits allocated to each. As shown in the figure, one slot includes “240 bits” of data, which corresponds to “120 symbols” of data. Therefore, if the number of quantization bits for AD conversion is 8 bits, the data amount per frame is 15360 bits. On the other hand, the data amount per slot is 1920 bits. The terminal device 10 in FIG. 1 detects a unique word included in the slot 1 from the frames transmitted from the plurality of base station devices 14 during the open search and the array search, and includes the unique word. Timing synchronization is established with the base station apparatus 14 that has transmitted the slot.

  Returning to FIG. The terminal device 10 executes an array search after executing an open search. As a result of the array search, the terminal device 10 establishes timing synchronization with any one of the plurality of base station devices 14. Further, communication with the base station apparatus 14 is determined. Here, since the procedure for establishing communication with the base station apparatus 14 is a known technique, a description thereof will be omitted. The plurality of base station apparatuses 14 are connected to a network (not shown).

  FIG. 3 shows the configuration of the terminal device 10. The terminal device 10 includes a first antenna 12a, a second antenna 12b, a fourth antenna 12d, which are collectively referred to as an antenna 12, and a first radio unit 20a, a second radio unit 20b, and a fourth radio unit 20d, which are collectively referred to as a radio unit 20. , Processing unit 22, modem unit 24, IF unit 26, synchronization unit 28, and control unit 30. As signals, the first radio unit side signal 200a, the second radio unit side signal 200b, the fourth radio unit side signal 200d, the modulation / demodulation unit side signal 202, the demodulated signal 220, and the timing information signal, which are collectively referred to as the radio unit side signal 200, are provided. 222 is included.

  As a reception operation, the antenna 12 receives a radio frequency signal from a base station device 14 (not shown). Further, the antenna 12 transmits a radio frequency signal to the base station device 14 (not shown) as a transmission operation. Note that the timing of the reception operation and the transmission operation is controlled by the control unit 30 described later. The antenna 12 corresponds to the adaptive array antenna technology, and the directivity of the antenna is controlled by a processing unit 22 described later. Here, the number of antennas 12 is “4”, but other numbers may be used.

  As a reception operation, the radio unit 20 performs frequency conversion on a radio frequency signal received by the antenna 12 to derive a baseband signal. The radio unit 20 outputs the baseband signal as the radio unit side signal 200 to the processing unit 22. Generally, a baseband signal is formed by an in-phase component and a quadrature component, so it should be transmitted by two signal lines, but here, it is shown as one signal line for the sake of clarity. Shall. An AGC and A / D converter are also included. As a transmission operation, the radio unit 20 performs frequency conversion on the baseband signal from the processing unit 22 and derives a radio frequency signal. Here, a baseband signal from the processing unit 22 is also shown as a radio unit side signal 200. The radio unit 20 outputs a radio frequency signal to the antenna 12. Further, a PA (Power Amplifier) and a D / A converter are also included.

  The processing unit 22 continuously inputs a signal from the base station apparatus 14, here, the radio unit side signal 200 without performing adaptive array signal processing during the open search period. That is, the processing unit 22 validates any one of the plurality of radio unit side signals 200 and outputs it as a modulation / demodulation unit side signal 202 to the modulation / demodulation unit 24. Such processing corresponds to setting the values for the radio unit side signals 200 other than one to “0” in the weight vectors for the plurality of radio unit side signals 200. As a result, in the open search period, the modulation / demodulation unit side signal 202 is equivalent to the result received by the omnidirectional antenna.

  The processing unit 22 inputs the radio unit side signal 200 while performing adaptive array signal processing during the array search period. At this time, the radio unit side signal 200 is continuously input at a timing designated by the control unit 30 described later. The timing at which the radio unit side signal 200 is input corresponds to the timing of the slot to which the control signal is assigned. The processing unit 22 outputs the result of the adaptive array signal processing as the modulation / demodulation unit side signal 202.

  After the array search period ends, the processing unit 22 performs adaptive array signal processing on the plurality of radio unit side signals 200 as a reception operation in communication. Further, the processing unit 22 performs adaptive array signal processing on the modulation / demodulation unit side signal 202 input from the modulation / demodulation unit 24 as a transmission operation. Further, the processing unit 22 outputs a signal subjected to adaptive array signal processing as a radio unit side signal 200.

  The modem unit 24 performs demodulation on the modem unit side signal 202 from the processing unit 22 as reception processing. The modem unit 24 outputs the demodulated signal as a demodulated signal 220 to the IF unit 26. Further, the modem unit 24 performs modulation as transmission processing. The modem unit 24 outputs the modulated signal to the processing unit 22 as the modem unit side signal 202. Here, π / 4 shift QPSK (Quadrature Phase Shift Keying) corresponding to the second generation cordless telephone system is used as the modulation method. On the other hand, the demodulation performs delay detection or synchronous detection.

  The IF unit 26 is connected to a display unit (not shown) or an input unit (not shown), and outputs a demodulated signal 220 to a display unit (not shown) as reception processing. Further, the IF unit 26 inputs data from an input unit (not shown) as a transmission process and outputs the data to the modem unit 24. In the case of voice communication, the IF unit 26 serves as an interface with a microphone and a speaker (not shown).

  The synchronization unit 28 receives the demodulated signal 220. During the open search period, the synchronization unit 28 detects a control signal from at least one base station apparatus 14 from the demodulated signal 220 input continuously. In order to detect the control signal, the synchronization unit 28 holds a unique word in advance, and calculates the correlation between the held unique word and the input demodulated signal 220. Furthermore, it is assumed that the synchronization unit 28 detects the control signal when the correlation value peak is compared with the threshold value and exceeds the threshold value. The control signal “CAC” includes the identification number (hereinafter referred to as “ID”) of the base station apparatus 14 that has transmitted the control signal, and the synchronization unit 28 detects the control signal. ID is also detected. The synchronization unit 28 performs the above processing until a predetermined number of control signals are detected. When the predetermined number of control signals are detected, the open search is terminated. Moreover, even if it is a case where a predetermined number of control signals are not detected, the synchronization unit 28 ends the open search when the second period is reached. The synchronization unit 28 measures the intensity of the detected signal and stores it. However, the synchronization unit 28 continues the open search until the first period when no control signal can be detected by the open search.

  Further, in the open search period, the synchronization unit 28 specifies the timing of the detected control signal. The timing is specified by detecting the timing corresponding to the peak of the correlation value. Further, the synchronization unit 28 also specifies the timing for each of the plurality of slots from the specified timing. That is, the timing corresponding to the peak of the correlation value corresponds to the UW timing in FIG. 2B, and is converted into the timing for the slot. For example, the timing for the slot is specified by shifting the UW timing forward.

  FIG. 4 shows the data structure of information stored in the synchronization unit 28. The data is No. A column 150, a timing column 152, an ID column 154, and a reception level column 156 are configured. No. A column 150 indicates a number assigned to the detected control signal. The timing column 152 indicates the timing of the slot to which the control signal is assigned. The timing is shown as “A” to “F”, but it is assumed that a numerical value indicating the timing is actually entered. The ID column 154 indicates the ID of the base station apparatus 14 that has transmitted the control signal. The synchronization unit 28 determines a search at the timing included in the timing column 152 and outputs the fact as a timing information signal 222. That is, a slot corresponding to the timing included in the timing column 152 is an array search target. The reception level column 156 indicates the strength of the signal detected by the synchronization unit 28.

  Returning to FIG. The synchronization unit 28 also inputs the demodulated signal 220 during the array search period. Further, the synchronization unit 28 detects a control signal from at least one base station apparatus 14 from the demodulated signal 220. The detection is performed at the head portion of the slot (hereinafter also referred to as “synchronization window”). It can be said that the head portion of such a slot is a period based on the specified timing. Since the slot timing is synchronized to some extent by open search, the array search period can be limited. The timing for detecting the control signal in the array search period is different from the timing in the open search period, but the detection method and the like are the same as in the open search period. The synchronization unit 28 selects one of the detected control signals as a result of the array search, and specifies the timing for the selected control signal again. The selection is performed based on the signal strength of the control signal, for example. At that time, the synchronization unit 28 selects the control signal that maximizes the signal strength. At this time, the stored signal strength is used.

  The timing is specified in the same manner as in the open search. In addition, when the terminal device 10 communicates with a plurality of base station devices 14, the synchronization unit 28 selects a plurality of control signals and identifies timings for them. When identifying the timing, the synchronization unit 28 identifies the base station device 14 corresponding to the timing while using the ID. The synchronization unit 28 outputs the identified timing and the base station device 14 as the timing information signal 222. Note that the array search ends when at least the first period is reached.

  The control unit 30 controls the operation of the components included in the terminal device 10. When the open search ends, the control unit 30 acquires timing via the timing information signal 222. Further, the control unit 30 instructs the processing unit 22 to perform the operation at the timing, particularly the head portion of the slot. The control unit 30 instructs the processing unit 22 to execute adaptive array signal processing. On the other hand, when the array search ends, the control unit 30 acquires the base station device 14 to be communicated and the timing for the base station device 14 via the timing information signal 222. The control unit 30 determines the communication with the base station device 14 and controls the operation of the components included in the terminal device 10 so as to execute the communication with the base station device 14.

  This configuration can be realized in terms of hardware by a CPU, memory, or other LSI of any computer, and in terms of software, it is realized by a program having a timing synchronization function loaded into the memory. The functional block realized by those cooperation is drawn. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  FIG. 5 shows the configuration of the processing unit 22. The processing unit 22 includes a synthesis unit 42, a reference signal generation unit 44, a reception weight vector calculation unit 54, a separation unit 46, and a transmission weight vector calculation unit 52. The combining unit 42 includes a first multiplying unit 56 a, a second multiplying unit 56 b, a fourth multiplying unit 56 d, and an adding unit 60 that are collectively referred to as the multiplying unit 56. The separation unit 46 includes a first multiplication unit 58a, a second multiplication unit 58b, and a fourth multiplication unit 58d, which are collectively referred to as a multiplication unit 58.

  The multiplying unit 56 weights each of the radio unit side signals 200 by the received weight vector from the received weight vector calculating unit 54, and the adding unit 60 adds the output of the multiplying unit 56. Here, the added signal is shown as a modulation / demodulation unit side signal 202. Note that the processing of the multiplication unit 56 and the addition unit 60 corresponds to synthesis while performing weighting. As described above, only one of the reception weight vectors is valid during the open search period, and therefore only the first multiplication unit 56a outputs the radio unit side signal 200. The adding unit 60 outputs the input radio unit side signal 200 as it is. As a result, in the open search period, the modem unit side signal 202 becomes equal to the first radio unit side signal 200a.

  The reference signal generation unit 44 outputs a training signal stored in advance as a reference signal during the period of the training signal. During these periods, the modem unit signal 202 is determined based on a predetermined threshold value, and the result is output as a reference signal. The determination may be a soft determination instead of a hard determination. Here, as shown in FIG. 2B, communication with the terminal device is performed in a predetermined slot. In the second generation cordless telephone system, a preamble is arranged at the head portion of the slot. Since the preamble is a known signal, it corresponds to a training signal.

  The reception weight vector calculation unit 54 derives a reception weight vector based on the radio unit side signal 200, the modulation / demodulation unit side signal 202, and the reference signal. The method for deriving the reception weight vector may be any method, one of which is the derivation by the LMS (Least Mean Square) algorithm.

  The transmission weight vector calculation unit 52 estimates a transmission weight vector necessary for weighting the modulation / demodulation unit side signal 202 from the reception weight vector. The method for estimating the transmission weight vector is arbitrary, but as the simplest method, the reception weight vector may be used as it is. Alternatively, the reception weight vector may be corrected by a conventional technique in consideration of the Doppler frequency fluctuation of the propagation environment caused by the time difference between the reception process and the transmission process. Here, it is assumed that the reception weight vector is used as it is as the transmission weight vector. Since no signal is transmitted during the open search and array search periods, the transmission weight vector calculation unit 52 operates after communication is started. The multiplication unit 58 weights the modulation / demodulation unit side signal 202 with the transmission weight vector, and outputs the result to the radio unit 20.

  FIG. 6 shows the configuration of the synchronization unit 28. The synchronization unit 28 includes a signal detection unit 110, an ID acquisition unit 112, a counter 114, and a specification unit 116. The signal detection unit 110 detects a control signal, particularly a unique word, from the demodulated signal 220. As described above, the signal detection unit 110 detects the control signal based on the correlation. When the signal detection unit 110 detects the control signal, the signal detection unit 110 notifies the identification unit 116 of the detection. The above processing is executed continuously during the open search period, but is executed at the beginning of the slot during the array search period.

  The counter 114 counts up at a timing corresponding to the sampling rate of the demodulated signal 220. The counter 114 resets the value counted up in a predetermined cycle, but it is preferable that a period obtained by multiplying the predetermined cycle by an integer corresponds to a period of one frame. The above processing is executed regardless of the open search and the array search.

  The ID acquisition unit 112 acquires the ID of the base station device 14 from the demodulated signal 220. That is, as described above, the ID acquisition unit 112 acquires an ID from “CAC” in FIG. Therefore, the detection of the control signal is acquired from the signal detection unit 110, and the timing of “CAC” is specified.

  The identification unit 116 acquires the count-up value from the counter 114 when notified of the detection of the control signal from the signal detection unit 110. That is, the count-up value at the time of detection of the control signal is specified as the aforementioned timing. Further, the identifying unit 116 identifies the slot timing from the identified timing. Further, the specifying unit 116 receives the ID of the base station apparatus 14 corresponding to the specified timing from the ID acquisition unit 112. The above processing is executed regardless of the open search and the array search. In the case of open search, based on these pieces of information, the specifying unit 116 stores the data shown in FIG.

  Further, the specifying unit 116 determines the end of the open search from the number of detected control signals or the open search period. Further, when the end of the open search is determined, the specifying unit 116 outputs the end of the open search, that is, the start of the array search as the timing information signal 222. On the other hand, in the case of array search, as described above, one timing and the base station apparatus 14 are selected. Furthermore, the specifying unit 116 outputs one timing and the base station apparatus 14 as the timing information signal 222. This corresponds to an instruction for communication with the base station apparatus 14.

  FIG. 7 shows an outline of timing at which the terminal apparatus 10 should operate. A frame similar to that shown in FIG. Here, since it corresponds to the processing before the start of communication with the base station apparatus 14, slots 1 to 8 are not distinguished as uplink or downlink. Therefore, for convenience, the numbers from slot 1 to slot 8 are simply assigned to the eight slots included in the period corresponding to the frame. In the case of open search, the terminal device 10 operates in all periods of eight slots. That is, as described above, the detection of the control signal is continuously executed. As a result of the open search, the timing corresponding to the slot is detected. Here, the start timing of the slot is detected.

  Therefore, in the case of array search, as shown in the figure, the terminal device 10 operates during the period of the head portion of the slot. Note that the period of the head portion of the slot is determined based on the timing detected by the open search. As a result of the array search, it is assumed that the terminal apparatus 10 determines communication in the base station apparatus 14 corresponding to any of slot 1, slot 2, slot 6, and slot 7. The slots for communication assigned by the base station apparatus 14 are slot 4 and slot 8. One of the slot 4 and the slot 8 corresponds to an uplink slot, and the other corresponds to a downlink slot. As a result, in the case of communication, the terminal device 10 operates in the slot 4 and the slot 8. Therefore, both control signal detection and adaptive array signal processing for the entire frame can be executed at different timings.

  The operation of the terminal device 10 having the above configuration will be described. FIG. 8 is a flowchart illustrating a procedure for establishing timing synchronization in the terminal device 10. The processing unit 22 sets the characteristics of the antenna 12 to be omnidirectional, and the synchronization unit 28 performs an open search (S10). If the signal detection unit 110 detects the control signal (Y in S12), the specifying unit 116 records the timing and ID corresponding to the control signal (S14). If the signal detection unit 110 does not detect the control signal (N in S12), step 14 is skipped. If the predetermined number of timings are detected (Y in S16), or if the predetermined number of timings are not detected (N in S16), the specifying unit 116 determines whether the second period has elapsed (Y in S18). The unit 116 sets the timing for opening the synchronization window for array search (S20). On the other hand, if the second period has not elapsed (N in S18), the process returns to step 10. In the period of the set synchronization window, the processing unit 22 and the synchronization unit 28 execute an array search (S22). The identifying unit 116 identifies the base station device 14 to be a communication target and the timing (S24). The array search is executed until the end of the first period at the latest. The terminal device 10 communicates with the base station device 14 (S26).

  FIG. 9 is a flowchart showing an open search procedure. This corresponds to step 10 in FIG. The modem unit 24 demodulates the modem unit side signal 202 (S30), and outputs a demodulated signal 220. The signal detection unit 110 performs a unique word search for the modulation / demodulation unit side signal 202 (S32). In addition, the signal detection unit 110 performs a CRC (Cyclic Redundancy Check) check on the modulation / demodulation unit side signal 202 that has executed the unique word search (S34). The case where the unique word is detected and no error is detected in the CRC check corresponds to the case where the unique word is detected. When the signal detection unit 110 detects a unique word (Y in S36), the specifying unit 116 acquires the timing and ID of the control signal including the unique word (S38). On the other hand, when the signal detection unit 110 does not detect the unique word (N in S36), the process returns to step 30.

  According to the embodiment of the present invention, as the first stage, the timing is specified from the signal continuously received without performing the adaptive array signal processing, and the second stage is based on the timing specified in the first stage. In addition, since the timing is specified while performing the adaptive array signal processing in a partial period, it is possible to shift the timing between the detection of the continuous control signal and the execution of the adaptive array processing. In addition, since continuous control signal detection and adaptive array processing are executed, detection accuracy can be improved while suppressing an increase in processing amount. In addition, since the period in which adaptive array signal processing is to be executed is a part of the time slot, adaptive array signal processing can be stopped in a period other than the period. In addition, since the signal is continuously received by the omnidirectional antenna characteristic first, a signal having a certain signal strength can be detected.

  In addition, since the open search and the array search are completed during the first period, the influence on the communication system can be reduced. Further, since switching from the open search to the array search is performed according to the number of detected control signals, it is possible to reduce the situation where the control signal cannot be detected in the array search. Even if the number of control signals that can be detected in the open search is small, switching from the open search to the array search is performed after the second period has elapsed, so that switching can be executed. Even when the base station apparatus performs transmission after assigning a signal to a predetermined slot, the timing for the slot can be specified. In addition, since there is a period during which execution of adaptive array signal processing is stopped, an increase in processing amount can be suppressed. Further, the base station apparatus corresponding to the timing can be specified while specifying the timing. Further, it is possible to proceed to a communication stage after establishing timing synchronization.

(Example 2)
As in the first embodiment, the second embodiment of the present invention relates to a terminal device that executes an array search after performing an open search. In the second embodiment, the demodulated signal is stored in the memory without performing the open search in real time, and then the open search is performed on the signal stored in the memory. According to such a process, when the period required for detecting the unique word is shorter than the period required for receiving the signal, the detection process can be intermittently operated. it can. As a result, power consumption can be reduced. Further, since the signal once stored is processed, more advanced processing is possible and the detection accuracy of the unique word can be improved. However, since it is necessary to store all slots in the open search, the storage capacity of the memory necessary for processing increases.

  In the second embodiment, the storage capacity of the memory is reduced by performing the following processing. The terminal device includes a memory capable of storing a data amount corresponding to one slot, and stores received data while cyclically overwriting the memory. On the other hand, the unique word detection is performed in a data unit corresponding to 1/2 slot (hereinafter referred to as “detection unit”), and is processed at a higher speed than the storage process of data corresponding to the detection unit in the memory. As a result, the data for which the unique word detection has been executed is deleted before the data stored in the memory becomes full, so even if the memory capacity of the memory is the amount of data corresponding to one slot, the received data Unique word detection processing can be performed without loss.

  FIG. 10 illustrates a configuration of the synchronization unit 28 according to the second embodiment. Here, the processing unit 22 and the modem unit 24 are also shown. The synchronization unit 28 includes a BB controller unit 120, an OSC 122, a storage unit 124, a UW detection unit 126, and a base station information storage unit 128. The signal includes a sample counter value 204, a slot counter value 206, and a sampling clock 208. For the sake of clarity, the following processing is targeted for the open search, but the same processing is also performed for the array search.

  The OSC 122 outputs a sampling clock 208 indicating timing at regular intervals. The BB controller unit 120 assigns a number to the data included in the modulation / demodulation unit side signal 202 by the sampling clock 208, and outputs the modulation / demodulation unit side signal 202 given the number. Finally, the timing for the slot from the predetermined base station apparatus 14 is stored based on the number. Specifically, a sample counter value 204 and a slot counter value 206 are output to indicate the data number. The slot counter value 206 indicates the slot number n, and the sample counter value 204 indicates the data number m in the slot. If the slot start position is f, the timing number x of the received signal is shown as follows.

(Equation 1)
x = f + n × m
The storage unit 124 stores the modulation / demodulation unit side signal 202 at an address corresponding to the number m indicated by the sample counter value 204. The storage capacity of the storage unit 124 is the data amount for one slot, which corresponds to the maximum value of the number m described above. When the period of one slot ends, the number m is reset, so that the modem unit side signal 202 is cyclically overwritten.

  The UW detection unit 126 performs unique word detection for each signal stored in the storage unit 124 in units of detection. When a unique word is detected, the timing number of the corresponding SS is reported to the modem unit 24. In addition, a plurality of timings for one base station apparatus 14 may be detected due to the influence of the radio propagation environment, but the UW detection unit 126 selects one timing based on the received power value and the like. The UW detection unit 126 intermittently detects a unique word from the stored signal, with a period shorter than the period of one slot as one detection unit. The UW detection unit 126 detects a unique word included in a plurality of detection units in order to detect a unique word stored in a plurality of detection units in the storage unit 124.

  As described above, the modem unit 24 delay-detects the modem unit signal 202. When a report of the SS timing number is received from the UW detection unit 126, a CRC check is performed based on the corresponding CRC timing number. As a result of the CRC check, it is assumed that the timing can be detected if there is no CRC error. At that time, the UW detection unit 126 determines the SS timing number as the head timing of the slot. It should be noted that the CRC check may be performed in the synchronization unit 28 as in the first embodiment. The base station information storage unit 128 stores the timing number of the base station apparatus 14 detected during the open search and other information. Details of the stored contents will be described later.

  FIG. 11 shows the configuration of the BB controller unit 120. The BB controller unit 120 includes a sample counter 70, a slot counter 72, and a buffer 74. The sample counter 70 generates a sample counter value 204 at the timing of the sampling clock 208. One slot is 120 symbols as described above, and one symbol is sampled 100 times. Therefore, the number m indicated by the sample counter value 204 is a value from 0 to 11999. The slot counter 72 indicates a slot counter value 206. The buffer 74 associates the modem side signal 202 with the sample counter value 204 and the slot counter value 206.

  FIG. 12 shows an outline of the operation of the UW detection unit 126. Here, a case will be described in which a unique word contained in the slot x + 1 is detected with the xth slot x and the x + 1th slot x + 1 being processed. Since data corresponding to one slot is stored in the storage unit 124, data in a period indicated as “write target data” in the drawing is written with the left end as the start address. In order to detect a unique word, the UW detection unit 126 reads the data in the section indicated as “read target data” in the drawing in two steps. Furthermore, in consideration of the case where a part of the unique word is included at the beginning or end of the period of the read data, it is indicated as “UW detection target data” in the figure including the data before and after that. Unique word detection is performed during a given period. Considering the case where the unique word extends over two detection units, the UW detection target data is shifted by the data amount obtained by subtracting one symbol length from the length of the unique word with respect to the detection unit. Here, when the unique word detection is performed on the second “read target data”, the unique word is detected.

FIG. 13 shows the data structure of information stored in the base station information storage unit 128. The data structure of FIG. 13 is similar to the data structure of FIG. A column 150, a timing column 152, and an ID column 154; Here, in the timing column 152, a timing number corresponding to the head of the slot is input. Here, five base station apparatuses 14 are detected. The timing Tss corresponding to the head of the slot is derived by the following calculation based on the timing Tuw corresponding to the unique word.
(Equation 2)
Tss = Tww-Cpr-Css

  Here, Cpr represents a count value corresponding to the preamble period, and Css represents a count value corresponding to the start symbol period. That is, the timing corresponding to the head of the slot is derived by shifting the timing corresponding to the unique word forward by the preamble period and the start symbol period. The UW detection unit 126 applies Equation 1 to the timing corresponding to the heads of the plurality of slots, and derives f of Equation 1, that is, the slot start position.

  The operation of the terminal device 10 having the above configuration will be described. FIG. 14 is a flowchart illustrating processing for acquiring timing. The storage unit 124 stores the received modulation / demodulation unit side signal 202 (S60). If the modulation / demodulation unit side signal 202 is not stored in the storage unit 124 for the detection unit (N in S62), the UW detection unit 126 waits for the modulation / demodulation unit side signal 202 to be stored without performing unique word detection. On the other hand, if the modulation / demodulation unit side signal 202 is stored in the storage unit 124 for each detection unit (Y in S62), the UW detection unit 126 intermittently performs unique word detection. If the unique word cannot be detected (N in S64), the processing from step 60 is repeated.

  On the other hand, if the unique word can be detected (Y in S64), the head timing of the slot corresponding to the unique word is stored in the base station information storage unit 128 (S66). Further, the modem unit 24 demodulates the modem unit side signal 202 and stores the demodulated signal 220 in the base station information storage unit 128 (S68). Further, the modem unit 24 performs a CRC check (S70), and if there is no CRC error (Y in S72), the timing at the head of the slot is acquired (S74). On the other hand, if there is a CRC error (N in S72), the processing from step 60 is repeated.

  FIG. 15 is a flowchart showing a process for storing received data. The sample counter 70 sets sample_count to 0 (S80). Note that sample_count is the same as the data number m in the aforementioned slot. If sample_count is not 12000 or more (N in S82), the BB controller unit 120 outputs the modulation / demodulation unit side signal 202 to the storage unit 124 using the sample_count as a data storage address (S84). On the other hand, if sample_count is equal to or greater than 12000 (Y in S82), sample_count is reset. If the modulation / demodulation unit side signal 202 does not end (N in S86), 1 is added to sample_count (S88). The above processing is executed until the modem unit side signal 202 ends (Y in S86).

  The operation of the terminal device 10 having the above configuration will be described. The processing unit 22 receives the radio unit side signal 200 and outputs it as the modulation / demodulation unit side signal 202 without executing the adaptive array signal processing. The BB controller unit 120 stores the modulation / demodulation unit side signal 202 in the storage unit 124 in units of one slot while assigning a number indicating timing. The UW detection unit 126 performs unique word detection on the data stored in the storage unit 124 according to the detection unit. If a unique word is detected, the modem unit 24 performs a CRC check after demodulation. If there is no CRC error, the number corresponding to the head of the slot is stored in the base station information storage unit 128 as timing. The above operation is performed on the plurality of base station apparatuses 14, and when a predetermined condition is met, the open search is terminated. After the open search is completed, an array search is executed.

  According to the embodiment of the present invention, since the capacity for storing the received data is only a data amount corresponding to one slot, the storage capacity can be reduced. Further, since the unique word detection process can be executed in a period shorter than the process period for storing the signal received in the storage unit, the unique word detection process can be executed intermittently, and the processing efficiency can be improved. Further, since data is once stored, complicated processing is possible, and the detection probability of a unique word can be improved.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

  In the first and second embodiments of the present invention, the communication system 100 has been described as a simple mobile phone system. However, the present invention is not limited to this, and the communication system 100 may be a mobile phone system. That is, the present invention is applicable to any system that detects a unique word included in a predetermined slot and establishes timing synchronization between the base station apparatus 14 and the terminal apparatus 10. According to this modification, it can be applied to various systems.

  In the second embodiment of the present invention, the UW detection unit 126 detects a unique word in a data unit corresponding to 1/2 slot as a detection unit. However, the present invention is not limited to this, and may be, for example, 1/3 or 1/4. According to this modification, the circuit scale can be reduced. That is, the detection unit may be a data amount smaller than the storage capacity in the storage unit 124.

1 is a diagram illustrating a configuration of a communication system according to a first embodiment. FIGS. 2A and 2B are diagrams showing the frame configuration and slot configuration of FIG. It is a figure which shows the structure of the terminal device of FIG. It is a figure which shows the data structure of the information memorize | stored in the synchronizer of FIG. It is a figure which shows the structure of the process part of FIG. It is a figure which shows the structure of the synchronizer of FIG. It is a figure which shows the outline | summary of the timing which the terminal device of FIG. 3 should operate | move. 4 is a flowchart illustrating a procedure for establishing timing synchronization in the terminal device of FIG. 3. It is a flowchart which shows the procedure of the open search of FIG. FIG. 6 is a diagram illustrating a configuration of a synchronization unit according to a second embodiment. It is a figure which shows the structure of the BB controller part of FIG. It is a figure which shows the operation | movement outline | summary of the UW detection part of FIG. It is a figure which shows the data structure of the information memorize | stored in the base station information storage part of FIG. FIG. 11 is a flowchart illustrating processing for obtaining timing in the synchronization unit of FIG. 10. FIG. 11 is a flowchart showing a process for storing received data in the synchronization unit of FIG. 10.

Explanation of symbols

  10 terminal device, 12 antenna, 14 base station device, 20 radio unit, 22 processing unit, 24 modem unit, 26 IF unit, 28 synchronization unit, 30 control unit, 100 communication system, 110 signal detection unit, 112 ID acquisition unit, 114 counter, 116 identification part.

Claims (8)

A receiving unit that receives signals without performing adaptive array signal processing; and
A signal detection unit for detecting a signal from at least one base station device from the signal received by the reception unit;
A specifying unit that specifies the timing of the signal detected by the signal detection unit;
In the receiving unit, when the timing is specified by the specifying unit, in the period based on the specified timing, execution of adaptive array signal processing is started,
The signal detection unit detects a signal from at least one base station device from the signal subjected to adaptive array signal processing in the reception unit,
The timing synchronizer characterized in that the specifying unit specifies the timing again for at least one of the signals detected by the signal detection unit. The signal from the base station apparatus is assigned to one of a plurality of time slots that constitute a frame,
The timing synchronization apparatus according to claim 1, wherein the specifying unit specifies timing for each of a plurality of time slots.   The timing synchronization apparatus according to claim 2, wherein a period in which adaptive array signal processing is to be executed in the receiving unit is a head portion of a time slot. The signal detection unit detects an identification number of the base station device included in the detected signal when detecting a signal from at least one base station device,
The specifying unit uses the identification number of the base station device when specifying the timing again for at least one of the signals detected by the signal detection unit, and the base station device corresponding to the timing is also used. 4. The timing synchronization apparatus according to claim 1, wherein the timing synchronization apparatus is specified.   The timing synchronization device according to claim 4, further comprising a determining unit that determines communication with the base station device specified by the specifying unit. The signal detector is
A storage unit for storing a signal received by the reception unit;
A unique word detection unit for detecting a unique word from the signal stored in the storage unit,
The storage unit has a storage area capable of storing a signal included in at least one time slot, and stores the received signal in the storage area while cyclically overwriting the received signal,
6. The unique word detection unit detects a unique word by using, as one detection unit, a data amount of a signal included in one area when the storage area is divided into a plurality of areas. The timing synchronizer described in 1.   The timing synchronization apparatus according to claim 6, wherein a storage capacity of a storage area included in the storage unit is set to a data amount of a signal included in substantially one time slot. A timing synchronization method for detecting a signal from at least one base station device from a signal received without performing adaptive array signal processing and identifying a timing of the detected signal,
When the timing is specified, a signal from at least one base station apparatus is detected while starting execution of adaptive array signal processing in a period based on the specified timing, and among the detected signals, A timing synchronization method, wherein the timing is specified again for at least one.

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