JP2010056741A - Receiving apparatus, reception control method, and reception control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce processing such as resynchronization processing and receiving processing of other synchronizing signals, and to reduce power to be consumed for the processing. <P>SOLUTION: A receiving apparatus for intermittently receiving synchronizing signals of at least two sorts and more transmitted from a transmitting apparatus so as to be used for time synchronization includes: a reception control part for measuring time for the time synchronization; a time lag detection part for detecting a time lag of time measured by the reception control part based on differences between the intermittently received synchronizing signals and a previously stored synchronizing signal; and a time lag detection signal determination part for determining synchronizing signals to be used for detection in the time lag detection part based on the measurement accuracy of time in the reception control part and sorts of codes to be used for the synchronizing signals. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a reception device, a reception control method, and a reception control program.

At present, the Evolved Universal Terrestrial Radio Access (hereinafter referred to as EUTRA) for the purpose of speeding up the communication speed by introducing a part of the technology considered for the fourth generation into the frequency band of the third generation mobile communication system. (Referred to as 3rd Generation Partnership Project) (Non-Patent Document 1).
In EUTRA, it is decided to adopt an OFDMA (Orthogonal Frequency Division Multiplexing Access) scheme that is resistant to multipath interference and suitable for high-speed transmission as a communication scheme. In addition, detailed specifications relating to upper layer operations such as data transfer control and resource management control related to EUTRA realize low delay and low overhead, and the adoption of simpler techniques as much as possible is being promoted.

  In the cellular mobile communication system, since a mobile station apparatus receives a signal transmitted from a base station apparatus in a cell or sector that is a communication area of the base station apparatus, synchronization between the slot and the frame in the radio frame of the base station apparatus is performed. It is necessary to take The base station apparatus transmits a synchronization channel SCH having a predetermined configuration, obtains a correlation with the synchronization channel SCH stored in advance in the mobile station apparatus, and synchronizes with the base station apparatus by detecting the synchronization channel SCH. . In EUTRA, a primary synchronization channel P-SCH (Primary SCH) and a secondary synchronization channel S-SCH (Secondary SCH) are prepared as synchronization channels SCH.

As shown in FIG. 9, the mobile station apparatus acquires slot synchronization (step 1) by taking a time domain correlation between the replica signal of the primary synchronization channel P-SCH and the received signal, and further acquires the secondary synchronization channel S. -SCH replica signal and received signal are correlated in time domain or frequency domain, and frame synchronization is obtained by the obtained transmission pattern of secondary synchronization channel S-SCH, and for identifying a base station apparatus A cell ID (Identification: identification information) is specified (step 2). By specifying the cell ID, it is possible to uniquely specify a downlink reference signal sequence used for downlink signal demodulation, reception quality measurement, and synchronization maintenance.
Such a series of control, that is, steps until the mobile station apparatus synchronizes with the base station apparatus and further specifies the cell ID of the base station apparatus is called cell search processing.

Further, the mobile station apparatus notifies the mobile communication system such as a mobile phone network of the cell location in which the mobile station apparatus is located through the base station apparatus, and the mobile communication system transmits information on the cell in which the mobile station apparatus is located. Is registered (hereinafter referred to as location registration). Thereby, the mobile communication system transmits a signal addressed to the mobile station device to the base station device of the cell where the location registration has been performed, and the mobile station device receives a signal addressed to itself from the base station device. Is possible.
The mobile station apparatus that has performed location registration can detect the presence or absence of a communication call addressed to itself (hereinafter referred to as a paging request) by demodulating the paging channel (PCH).

 In a communication system, when a mobile station apparatus receives an incoming call, it is necessary to notify the mobile station apparatus accordingly. The network manages the location information of the mobile station device in the location registration area, and broadcasts that all mobile station devices in the location registration area where the mobile station device is registered are received. Notice. This procedure is called paging. Paging is performed from all base station apparatuses accommodated in the registered location registration area to the mobile station apparatus. Since the mobile station apparatus constantly monitors the PCH signal in the idle mode (standby state), the mobile station apparatus can recognize the paging for the own apparatus, and the location registration area and ID included in the paging request can be recognized. When a predetermined parameter such as a location registration area or ID stored therein matches, a response is returned to the network.

Next, an outline of the main physical channels and transport channels of WCDMA related to paging will be briefly described.
The paging indicator channel PICH is a downlink common channel and exists in a pair with a paging channel PCH (Paging Channel) of a transport channel corresponding to the second common control physical channel S-CCPCH to which a signal for paging is mapped. Then, the presence / absence of voice call (CS: Circuit Switch) or packet call (PS: Packet Switch) incoming call information for each incoming call group that is a collection of mobile station devices is transmitted. When the mobile station apparatus belonging to the incoming call group #n is notified that there is an incoming call for the incoming call group #n in the paging indicator channel PICH, the corresponding radio mapped to the second common control physical channel S-CCPCH The paging channel PCH in the frame is received to determine whether there is an incoming call.

The paging indicator channel PICH is a channel set for the purpose of reducing an intermittent reception IR (Intermittent Reception) ratio in order to improve battery saving of the mobile station apparatus. The paging indicator channel PICH transmits a short paging indicator PI (Paging Indicator) to the mobile station apparatus belonging to the incoming call group #n to notify the presence / absence of an incoming call to the mobile station apparatus. The device normally receives only this paging indicator PI. The mobile station apparatus receives the paging channel PCH corresponding to the paging indicator PI only when notified by the paging indicator PI that there is an incoming call.
Since the paging indicator PI is grouped into a plurality of incoming groups #n and the incoming frequency per incoming group #n can be extremely low, the mobile station device in the idle mode can receive only a short paging indicator PI. The frequency of receiving the signal of the long paging channel PCH (the amount of information is large) can be extremely low.

Further, paging in EUTRA will be described. Before explaining paging, FIG. 10 shows an example of a radio signal configuration of a downlink signal in EUTRA.
In FIG. 10, the horizontal axis represents the time axis, and the vertical axis represents the frequency axis. The radio frame is configured with a frequency domain (BR) composed of a set of a plurality of subcarriers on the frequency axis and a region composed of a constant transmission time (slot) as a unit. (Non-Patent Document 1)
A transmission time constituted by an integral multiple of one slot is called a subframe. Further, a group of a plurality of subframes is called a frame. FIG. 10 shows a case where one subframe is composed of two slots. A region divided by a certain frequency region (BR) and one slot length is called a resource block. One frame is composed of 10 subframes. BW in FIG. 10 indicates the system bandwidth, and BR indicates the bandwidth of the resource block.

  FIG. 11 is a diagram illustrating an example of a primary synchronization channel P-SCH, a secondary synchronization channel S-SCH, and a downlink reference signal in a frame of EUTRA. In the figure, one subframe is composed of 14 OFDM symbols. Further, 1BR is assumed to be composed of 12 subcarriers. As shown in FIG. 11, the secondary synchronization channel S-SCH and the primary synchronization channel P-SCH are 6BR at the center of the transmission frequency band of the base station apparatus, and are transmitted at the 6th and 7th OFDM symbols of subframes # 0 and # 5, respectively. Is done. The downlink reference signal differs depending on the number of transmission antennas of the base station apparatus, but is always arranged in the first OFDM symbol of each subframe regardless of the number of antennas. In addition, a physical downlink control signal is arranged at a location other than the downlink reference signal in the first n OFDM symbols (1 ≦ n ≦ 3) of each subframe.

  In EUTRA paging processing, in the frame configuration, the mobile station apparatus receives a signal corresponding to a paging indicator PI included in a physical downlink control signal arranged at the head of each subframe. The mobile station apparatus that has received the signal demodulates information corresponding to the paging channel PCH included in the OFDM symbol after the physical downlink control signal of the subframe, and confirms the presence / absence of a signal addressed to itself.

  Although the mobile station device needs to monitor a signal for paging, a delay of several hundred ms to several seconds is not a big problem in the case of a voice call or mail arrival. In other words, it is possible to arrange paging at intervals of several hundred ms to several seconds, and the mobile station apparatus can receive radio waves only in the section where the paging is arranged and check whether there is paging addressed to itself. it can. It is possible to save power by stopping the wireless transmission / reception operation other than the intermittent reception period.

The mobile station apparatus that has performed the synchronization process by the cell search process described above performs the reception process of the downlink reference signal, the synchronization channel SCH, and the paging signal (communication request signal) by the intermittent reception process. At this time, since the time measurement accuracy performed by each of the base station device and the mobile station device is different, a synchronization time shift (hereinafter referred to as a synchronization time shift) may occur depending on the time measurement accuracy of each device. is there.
In order to correct this synchronization time lag, the mobile station apparatus uses a known signal (for example, primary synchronization channel P-SCH, secondary synchronization channel S-SCH, or downlink reference signal) sent from the base station apparatus at a known timing. The synchronization is maintained by detecting the synchronization time shift using this known signal and correcting the synchronization time shift.
In WCDMA, a known signal for correcting a synchronization time shift is a long code PN code or the like.

One method for correcting the synchronization timing shift in WCDMA is described in Patent Document 1. In Patent Document 1, the mobile station apparatus receives and holds a 64-bit long code PN code at the start of intermittent reception, and sets a code assumed to be received by time m before the intermittent reception timing as an initial phase. Thereafter, the envelope value is accumulated by despreading sequentially using the held received code and the phase from the initial phase to time 2 m. By detecting the maximum value from the accumulated envelope value, the actual reception timing in the range of ideal timing ± m of intermittent reception can be detected. If the maximum value is below the predetermined threshold value, it is assumed that the value is out of the range of ± m, and resynchronization processing (search operation), which is cell resynchronization processing, is performed.
In this way, since long-cycle signals can always be received in WCDMA, synchronization correction can be performed relatively easily. However, in EUTRA, since long-cycle signals are not used as known signals, Since the above method cannot be used, it is necessary to perform correction using a synchronization channel or a downlink reference signal.

In EUTRA, since the received signal is normally subjected to FFT processing and handled as a frequency domain signal, it is desirable that detection of a synchronization time shift can also be detected in the frequency domain.
If the received signal F ′ of the downlink reference signal in the frequency domain is shifted in time τ from the correct timing, the received signal F of the downlink reference signal when there is no time shift stored in advance by the mobile station apparatus (formula (1)) It is shown by Formula (2) using

Here, e is the number of Napiers (base of natural logarithm), j is an imaginary unit, ω is the frequency (angular velocity) of the subcarrier, and f (t) is a received signal in the time domain.
The mobile station apparatus detects e ^{jθ (ω)} by detecting the received signal F ′ (ω) of the downlink reference signal and dividing F (ω). Here, since the phase θ (ω) is a periodic value, in order to uniquely detect the synchronization time shift τ, the phases θ (ω ₁ ), θ (ω) at certain frequencies ω ₁ and ω ₂ are used. ₂ ), that is, θ (ω ₁ ) −θ (ω ₂ ) needs to satisfy −π <θ (ω ₁ ) −θ (ω ₂ ) <π. In this case, the equation (2), the synchronization time shift τ, τ = - (θ ( ω 1) -θ (ω 2)) / (ω 1 -ω 2) as can be uniquely detected.

_{Incidentally, θ (ω 1) -θ (} ω 2) _{is, -π <θ (ω 1)} -θ (ω 2) < If a value other than [pi, the one [pi more values are the following value - [pi] Therefore, the synchronization time lag τ cannot be uniquely detected. In this case, the mobile station apparatus cannot maintain synchronization, and requires another synchronization process (hereinafter referred to as resynchronization process).
The method for detecting the synchronization time difference τ is the same for the synchronization channel SCH. In order to detect a wider synchronization time shift τ, ω ₂ −ω ₁ = Δω needs to be set small. Hereinafter, the correction of the synchronization time shift τ (processing for shifting τ to 0 by shifting the signal reception timing by τ) is referred to as synchronization time shift correction.

Of the primary synchronization channel P-SCH, secondary synchronization channel S-SCH, and downlink reference signal currently being studied by EUTRA, the primary synchronization channel P-SCH and the secondary synchronization channel S-SCH are arranged on all subcarriers. However, with regard to the downlink reference signal, the arrangement of every 6 subcarriers is being studied. In a simple comparison, the synchronization time lag τ using the primary synchronization channel P-SCH and the secondary synchronization channel S-SCH can be detected, that is, the range in which the synchronization time lag can be corrected is considered to be 6 times that of the downlink reference signal. Can do.
When a plurality of orthogonal codes using phase rotation is used as the downlink reference signal, for example, the phase rotation is [0, 0, 0, 0, 0,...], [0, 2 / 3π, 4 / 3π, 6 / 3π (= 0), 8 / 3π (= 2 / 3π), ...], [0, 4 / 3π, 8 / 3π, 12 / 3π (= 0), 16 / 3π (= 4 When three orthogonal codes shifted by 2 / 3π are used as downlink reference signals, when downlink reference signals (interference radio waves) from a plurality of sectors and base station apparatuses are received, θ When the value of (ω ₁ ) −θ (ω ₂ ) is equal to or larger than π / 3, which is half of the phase difference 2 / 3π, the phase rotation applied to the downlink reference signal is identified from the phase rotation caused by the synchronization time shift. Can not be. Therefore, the range in which the synchronization time shift τ can be detected is −π / 3 <Δωτ <π / 3, and the range in which the synchronization time shift can be corrected using the downlink reference signal is narrowed.

The range in which synchronization time deviation correction in EUTRA can be performed in consideration of the above method is described in Non-Patent Document 2, and the value is ± 1... When orthogonal codes using phase rotation are used for the downlink reference signal. 9 [μs], and ± 5.6 [μs] when the orthogonal code is not used. In WCDMA, the range in which the synchronization time deviation can be corrected is ± 33 [μs].
As described above, when the synchronization time shift τ is small, the synchronization time shift τ can be corrected using the downlink reference signal. However, when the shift is large, two locations (one location in 5 ms) are placed. It is necessary to correct using the synchronization channel SCH. This means that it is necessary for the mobile station apparatus to demodulate a subframe including the synchronization channel SCH in addition to a subframe in which data is received.

Further, in Patent Document 2, a timer is counted, and a technique for correcting the DRX cycle timing from a deviation before and after that is corrected, or a low-accuracy clock that measures a DRX cycle is corrected using a high-accuracy clock used at the time of communication. Techniques are described.
3GPP TS (Technical Specification) 36.211, Physical Channels and Modulation. V8.0.0 http: // www. 3 gpp. org / ftp / Specs / html-info / 36211. htm Nokia, “Performance of Orthogonal Sequences for Reference Signals”, R1-080289, 3GPP TSG-RAN WG1 Meeting # 51bis, Seville, Spain 18u18 18 Japanese Patent Laid-Open No. 11-284599 JP-A-9-93185

However, in the maintenance of synchronization, the range of the magnitude of the time shift that can be detected differs depending on the type of sign of the synchronization signal used for detecting the synchronization time shift. In the conventional technique, since the synchronization time lag is not detected based on the type of code of the synchronization signal, the conventional receiving apparatus cannot maintain the synchronization if the synchronization time lag is too large to detect, and again There is a drawback that power is consumed in the synchronization processing (hereinafter referred to as re-synchronization processing) and other synchronization signal reception processing capable of detecting a synchronization time shift.
Further, in the technique described in Patent Document 2, resynchronization processing is performed even in a receiver in the same communication system due to a difference in measurement accuracy of time such as a difference in accuracy of a quartz oscillator of a timer used in the receiver. There is a receiving apparatus that is necessary and a receiving apparatus that is not necessary, and a receiving apparatus that requires resynchronization processing has a drawback in that power is consumed for the processing.
As described above, in the receiving apparatus of the conventional technique, depending on the type of the code of the synchronization signal used for detecting the synchronization time lag, it is necessary to perform processing such as resynchronization processing and reception processing of other synchronization signals. However, there is a disadvantage that power is consumed.

  The present invention has been made in view of the above points, and an object of the present invention is to reduce processing such as resynchronization processing and reception processing of other synchronization signals, and to reduce power consumed in the processing. An object of the present invention is to provide a receiving device, a receiving control method, and a receiving control program.

(1) The present invention has been made to solve the above-described problem, and one aspect thereof is a receiving apparatus that intermittently receives at least two types of synchronization signals used for time synchronization transmitted from a transmitting apparatus. A reception control unit that measures time for the time synchronization; and a time shift detection unit that detects a time shift measured by the reception control unit due to a difference between the synchronization signal received intermittently and the synchronization signal stored in advance. A time shift detection signal determination unit that determines the synchronization signal used for detection by the time shift detection unit based on the measurement accuracy of time in the reception control unit and the type of code used for the synchronization signal; Is provided.
According to the above configuration, the receiving device detects a time difference measured for time synchronization with the transmitting device, based on the time measurement accuracy of the device itself and the type of code used for the synchronization signal. Since the synchronization signal to be used is determined, time synchronization can be performed using an appropriate signal capable of maintaining synchronization, and power consumption can be reduced by reducing resynchronization processing.

(2) Further, according to one aspect of the present invention, the time lag detection signal determination unit may detect the time lag so that the time lag detection unit can uniquely detect a time lag measured by the reception control unit. The synchronization signal used for detection by the unit is determined.
According to the above configuration, the receiving apparatus determines the synchronization signal used for detection by the time shift detection unit so that the time shift measured by the reception control unit can be uniquely detected. Can be detected and the synchronization can be maintained, and the power consumption of the synchronization processing and resynchronization processing by other means can be reduced.

(3) In addition, according to an aspect of the present invention, the transmission apparatus receives a communication request signal transmitted in a subframe that is a transmission interval at which a signal is transmitted, and transmits at least two types of synchronization. The signal is a first synchronization signal arranged in each subframe and a second synchronization signal arranged in the predetermined subframe, and the interval between the arranged subcarriers is the first synchronization signal. A second synchronization signal that is smaller than an interval between subcarriers in which the signal is arranged, and the time shift detection signal determination unit prioritizes the first synchronization signal over the second synchronization signal, The synchronization signal used for detection by the time shift detection unit is used.
According to the above configuration, the reception device is arranged for each subframe, and gives priority to the first synchronization signal arranged in the subframe in which the communication request signal is arranged, and the synchronization signal for detecting a time lag Therefore, the first synchronization signal and the communication request signal can be received by the same reception process, and the power related to reception is reduced compared to the case where each signal is received individually in different subframes. be able to.

(4) According to another aspect of the present invention, the receiving apparatus receives information indicating a type of code used for the synchronization signal transmitted by another transmitting apparatus adjacent to the transmitting apparatus, and detects the time lag. The signal determination unit uses the time deviation detection unit for detection based on the measurement accuracy of time in the reception control unit, the type of code used for the synchronization signal, and the type of code represented by the received information. Determine the synchronization signal.
According to the above configuration, the reception apparatus determines the synchronization signal used for detection by the time shift detection unit based on a type of code used for the synchronization signal transmitted by another transmission apparatus adjacent to the transmission apparatus. Therefore, even when the range in which the time lag can be detected differs depending on the type of code used for the synchronization signal transmitted by the other transmission device, the time lag can be reliably detected to maintain synchronization. Therefore, it is possible to reduce the power consumption required for the synchronization processing by other means and the resynchronization processing.

  (5) Further, according to one aspect of the present invention, the information indicating the type of code used for the synchronization signal transmitted by another transmitting apparatus is the type of signal transmitted by the other transmitting apparatus, and the time shift The detection signal determination unit detects the time deviation based on the measurement accuracy of time in the reception control unit, the type of code used for the synchronization signal, and the type of signal transmitted by the other transmission device. The synchronization signal to be used is determined.

(6) Further, according to one aspect of the present invention, the code used for the synchronization signal includes an orthogonal code using phase rotation, and the type of the code used for the synchronization signal is a type representing the phase rotation amount. Including.
According to the above configuration, the receiving apparatus determines the synchronization signal used for detection by the time shift detection unit according to whether or not the type of code used for the synchronization signal is an orthogonal code using phase rotation. Therefore, even when an orthogonal code using phase rotation is used, it is possible to reliably detect an accurate time lag and maintain synchronization. The power consumption for the synchronization process can be reduced.

  (7) According to another aspect of the present invention, in the reception control method in the reception device that intermittently receives at least two types of synchronization signals used for time synchronization transmitted from the transmission device, the reception device includes the time synchronization. The difference between the first process for measuring the time for and the intermittently received synchronization signal and the synchronization signal stored in advance is detected by the receiving apparatus to detect the time difference measured in the first process The synchronization used by the second process for detection in the second process based on the time measurement accuracy in the first process and the type of code used for the synchronization signal in the second process. A third step of determining the signal.

  (8) Further, according to one embodiment of the present invention, a reception device that intermittently receives at least two types of synchronization signals used for time synchronization transmitted from a transmission device, and that receives time for measuring the time for the time synchronization. Control means, time difference detection means for detecting a time difference measured by the reception control means due to the difference between the intermittently received synchronization signal and the synchronization signal stored in advance, time measurement accuracy in the reception control means, Based on the type of code used for the synchronization signal, the time shift detection means functions as time shift detection signal determination means for determining the synchronization signal used for detection.

  According to the present invention, the receiving apparatus detects a time lag to be measured for time synchronization with the transmitting apparatus based on the time measurement accuracy in the own apparatus and the type of code used for the synchronization signal. Since the synchronization signal to be used is determined, time synchronization can be performed using an appropriate signal capable of maintaining synchronization, and power consumption can be reduced by reducing resynchronization processing for performing time synchronization again. .

<About communication systems>
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a conceptual diagram of a communication system 1 according to an embodiment of the present invention.
In this figure, the communication system 1 is configured to include base station apparatuses A1 and A2 (transmitting apparatus) and mobile station apparatuses B1 to B3 (receiving apparatus). In this figure, a base station apparatus A1 and a base station apparatus A2 are adjacent base station apparatuses, and communicate with each other via a mobile phone network C.
Hereinafter, the base station apparatus A1 and the mobile station apparatuses B1 and B2 will be described, but the same applies to the base station apparatus A2 and the mobile station apparatus B3.

Since the mobile station apparatuses B1 and B2 communicate with the base station apparatus A1, as will be described later, the mobile station apparatuses B1 and B2 synchronize the slots and frames with the base station apparatus A1 by cell search processing (hereinafter referred to as synchronization processing).
After performing this synchronization processing, the mobile station apparatuses B1 and B2 receive a call from the base station apparatus A1 until there is a call for communication addressed to the own apparatus such as an incoming call addressed to the own apparatus (hereinafter referred to as a paging request). A signal is received to enable communication. At this time, the mobile station apparatuses B1 and B2 intermittently receive a signal from the base station apparatus A1 (hereinafter referred to as intermittent reception) in order to reduce power consumption.
In addition, the mobile station devices B1 and B2 measure time by using the time counting function of the own device in order to maintain synchronization with the base station device A1. The measurement accuracy of this time varies depending on the functions and quality of the mobile station apparatuses B1 and B2.

  On the other hand, the signals received intermittently by the mobile station devices B1 and B2 include a downlink reference signal (first synchronization signal), which is a known signal used for time synchronization, and a synchronization channel SCH (Synchronization Channel), as described later. Synchronization signal). The downlink reference signal is also a signal used for propagation path compensation.

  First, the mobile station apparatuses B1 and B2 use the downlink reference signal transmitted by the base station apparatus A1 to cause a time synchronization time shift with the base station apparatus A1 caused by time measurement accuracy (hereinafter referred to as a synchronization time shift). Is detected and the synchronization time shift is corrected (hereinafter referred to as synchronization time shift correction) to maintain synchronization (hereinafter referred to as synchronization maintenance processing). The range of the magnitude of the time shift that can detect this synchronization time shift is limited by the time measurement accuracy of each of the mobile station apparatuses B1 and B2 and the synchronization signal used for detecting the synchronization time shift. In addition, when the synchronization time difference cannot be detected, the mobile station apparatuses B1 and B2 need to perform resynchronization processing.

In this embodiment, the mobile station apparatuses B1 and B2 detect the synchronization time shift using the downlink reference signal based on the time measurement accuracy of the own apparatus and the type of code used for the downlink reference signal. It is determined whether or not
As a result of the determination, when the mobile station apparatuses B1 and B2 can detect the synchronization time shift using the downlink reference signal, the synchronization time shift detection is performed using the downlink reference signal arranged in the same subframe as the paging signal. Then, the synchronization maintaining process is performed and the paging signal is received. As a result of the determination, when the mobile station apparatuses B1 and B2 cannot detect the synchronization time shift using the downlink reference signal, the synchronization channel SCH is different in a subframe different from the subframe in which the paging signal is to be arranged. , Detects a synchronization time shift using the received synchronization channel SCH, performs synchronization maintenance processing, and receives a paging signal.
In this way, the communication system 1 synchronizes using an appropriate synchronization signal that can detect a synchronization time shift based on the time measurement accuracy of the own device and the type of code used for the downlink reference signal. Maintenance processing can be performed, and power consumption can be reduced by reducing resynchronization processing and synchronization channel SCH reception processing.

  Hereinafter, cell search processing (synchronization processing) between the mobile station devices B1 and B2 and the base station device A1, processing for intermittently receiving signals from the base station device A1, radio frame configuration, and synchronization maintenance processing will be described. Next, the configuration and operation of the apparatus according to the present embodiment will be described.

<About cell search processing>
Hereinafter, the cell search process will be described.
In the communication system 1, since the mobile station apparatuses B1 and B2 receive a signal transmitted from the base station apparatus A1 in a cell or sector that is a communication area of the base station apparatus A1, a radio frame of the base station apparatus A1 described later is received. It is necessary to synchronize the slot and frame in The base station apparatus A1 transmits the synchronization channel SCH having a predetermined configuration, correlates with the synchronization channel SCH stored in advance in the mobile station apparatuses B1 and B2, and detects the synchronization channel SCH, thereby the base station apparatus Synchronize with A1. Here, there are a primary synchronization channel P-SCH (Primary SCH) and a secondary synchronization channel S-SCH (Secondary SCH) as the synchronization channel SCH.

FIG. 2 is a flowchart showing cell search processing according to the present embodiment.
The mobile station apparatuses B1 and B2 obtain slot synchronization (step 1) by correlating the replica signal of the primary synchronization channel P-SCH and the received signal in the time domain, and further replicating the secondary synchronization channel S-SCH. The signal and the received signal are correlated in the time domain or the frequency domain, and the frame synchronization is obtained by the obtained transmission pattern of the secondary synchronization channel S-SCH, and the cell ID (for identifying the base station apparatus A1) Identification (identification information) is specified (step 2). By specifying the cell ID, it is possible to uniquely specify a downlink reference signal sequence used for downlink signal demodulation, reception quality measurement, and synchronization maintenance.
Such a series of control, that is, the steps until the mobile station apparatuses B1 and B2 synchronize with the base station apparatus A1 and specify the cell ID of the base station apparatus A1 is called cell search processing.

Further, the mobile station devices B1 and B2 notify the mobile communication system 1 such as a mobile phone network of cell information in which the mobile device is located through the base station device A1, and the mobile communication system 1 Information on the cell where B2 is located is registered (hereinafter referred to as location registration). As a result, the mobile communication system 1 transmits signals addressed to the mobile station devices B1 and B2 to the base station device A1 of the cell where the location registration has been performed. It becomes possible to receive a signal addressed to the apparatus.
The mobile station devices B1 and B2 that have not performed location registration, or the mobile station devices B1 and B2 that have moved from the cell to which location registration has been performed to another cell, the base station device A1 of the cell detected by the cell search process. To communicate and perform location registration.
The mobile station apparatuses B1 and B2 that have performed location registration can detect the presence or absence of a paging request by demodulating the paging signal arranged in the paging channel (PCH).

<Intermittent reception processing>
Hereinafter, the intermittent reception process will be described.
FIG. 3 is a timing chart illustrating the intermittent reception process according to the present embodiment. In this figure, the horizontal axis is the time axis.
This figure shows that the mobile station apparatus B1 repeats reception and sleep to intermittently receive signals from the base station apparatus A1 in order to reduce power consumption. Also, the mobile station device B1 periodically performs this intermittent reception. The time from this reception time to the next reception time is called a DRX cycle.

This figure shows that the mobile station apparatus B1 receives the paging signal p1 addressed to the mobile station apparatus B1 transmitted by the base station apparatus A1, and then receives the data signal p2 addressed to the mobile station apparatus B1. .
In this way, the mobile station apparatus B1 detects the paging signal addressed to itself, and only when it detects it, makes the reception possible by increasing the interval at which reception is possible and receiving the data signal addressed to itself. Time can be reduced, and power consumption enabling reception can be reduced.
The base station apparatus A1 arranges the paging signal p1 so that the paging signal p1 can be received when the mobile station apparatus B1 is receiving intermittently.

<About wireless frame configuration>
The radio frame configuration according to this embodiment will be described below.
FIG. 4 is an explanatory diagram illustrating the configuration of a radio frame according to the present embodiment. In this figure, the horizontal axis is the time axis, and the vertical axis is the frequency axis.
The radio frame is configured with a frequency domain (BR) composed of a set of a plurality of subcarriers on the frequency axis and a region composed of a constant transmission time (slot) as a unit. A transmission time constituted by an integral multiple of one slot is called a subframe. Further, a group of a plurality of subframes is called a frame.
FIG. 4 shows a case where one subframe is composed of two slots. A region divided by a certain frequency region (BR) and one slot length is called a resource block. One frame is composed of 10 subframes. BW in FIG. 4 indicates the system bandwidth, and BR indicates the bandwidth of the resource block.

FIG. 5 is an explanatory diagram for explaining the arrangement of signals according to the present embodiment. In this figure, the vertical axis is the frequency axis and the horizontal axis is the time axis.
This figure shows an example of the arrangement of the primary synchronization channel P-SCH, secondary synchronization channel S-SCH, and downlink reference signal in the frame. In this figure, one subframe is composed of 14 OFDM symbols. One BR is composed of 12 subcarriers.

In this figure, the secondary synchronization channel S-SCH and the primary synchronization channel P-SCH are 6BR at the center of the transmission frequency band of the base station apparatus, and are arranged in the 6th and 7th OFDM symbols of subframes # 0 and # 5, respectively. Indicates. The broadcast information channel is arranged in the same subframe as the synchronization channel SCH.
Further, in this figure, the downlink reference signal is always arranged in the first OFDM symbol of each subframe. Also, it is indicated that the physical downlink control signal is arranged at a location other than the downlink reference signal in the first n OFDM symbols (1 ≦ n ≦ 3) of each subframe.
In the TDD (Time Division Duplex) system as well, the above arrangement is applied to the subframes assigned to the downlink.

Here, in the primary synchronization channel P-SCH and the secondary synchronization channel S-SCH, signals are arranged on all subcarriers. Further, the downlink reference signal is arranged every 6 subcarriers.
As will be described later, due to the difference in arrangement of the subcarriers, the synchronization channel SCH and the downlink reference signal have different ranges in which the synchronization time shift can be detected.

<About synchronization maintenance processing>
The mobile station apparatuses B1 and B2 that have performed the synchronization process by the cell search process described above perform the reception process of the downlink reference signal, the synchronization channel SCH, and the paging signal by the intermittent reception process. At this time, since the time measurement accuracy performed by each of the base station device A1 and the mobile station devices B1 and B2 is different, a synchronization time shift may occur depending on the time measurement accuracy of each device.
In order to correct this synchronization time lag, the mobile station apparatuses B1 and B2 transmit a known signal (for example, primary synchronization channel P-SCH, secondary synchronization channel S-SCH, or downlink) sent from the base station apparatus A1 at a known timing. Reference signal) is received, a synchronization time lag is detected using this known signal, and synchronization time lag correction is performed to perform synchronization maintenance processing.

For example, the mobile station apparatuses B1 and B2 can detect a synchronization time shift using the downlink reference signal as follows.
The received signal F ′ (ω) of the downlink reference signal in the frequency domain is shifted by time τ from the correct timing due to time measurement accuracy, that is, when the synchronization time shift is τ, the mobile station apparatuses B1 and B2 Using the received signal F (ω) (formula (3)) of the downlink reference signal when there is no synchronization time shift τ stored in advance, it is expressed by formula (4).

Here, e is the number of Napiers (base of natural logarithm), j is an imaginary unit, ω is the frequency (angular velocity) of the subcarrier, and f (t) is a received signal in the time domain.
The mobile station devices B1 and B2 detect the received signal F ′ (ω) of the downlink reference signal and divide F ^(ω) to detect e ^{jθ (ω)} . Here, since the phase θ (ω) is a periodic value, in order to uniquely detect the synchronization time shift τ, the phases θ (ω ₁ ), θ (ω) at certain frequencies ω ₁ and ω ₂ are used. ₂ ), that is, θ (ω ₁ ) −θ (ω ₂ ) needs to satisfy −π <θ (ω ₁ ) −θ (ω ₂ ) <π. In this case, the synchronization time shift τ can be uniquely detected from the equation (4) as τ = − (θ (ω ₁ ) −θ (ω ₂ )) / (ω ₁ −ω ₂ ).

_{Incidentally, θ (ω 1) -θ (} ω 2) _{is, -π <θ (ω 1)} -θ (ω 2) < If a value other than [pi, the one [pi more values are the following value - [pi] Therefore, the synchronization time lag τ cannot be uniquely detected. In this case, the mobile station apparatus cannot maintain synchronization and needs resynchronization processing.
Here, since −ωτ is a phase rotation, if the phase difference between certain frequencies ω ₁ and ω ₂ , that is, ω ₂ τ−ω ₁ τ = Δωτ is −π <Δωτ <π, θ ( By detecting ω ₁ ) and θ (ω ₂ ), the synchronization time shift τ can be uniquely detected.
If Δωτ takes a value other than −π <Δωτ <π, it cannot be determined whether it is a value less than −π or a value greater than or equal to π, so that the synchronization time shift τ cannot be uniquely detected. In this case, the mobile station apparatus cannot maintain synchronization, and requires another synchronization process (hereinafter referred to as resynchronization process).

Further, the sampling interval Δω = ω ₂ −ω ₁ in the frequency domain differs between the downlink reference signal and the synchronization channel SCH. The synchronization channel SCH arranged in all subcarriers has a smaller Δω than the downlink reference signal arranged every 6 subcarriers, that is, the range in which the synchronization time shift τ can be uniquely detected.

When orthogonal codes are used for the downlink reference signal, m codes (hereinafter referred to as 2π / m shift codes) shifted by 2π / m (m is a natural number) are used. In this case, in consideration of interference radio waves from other sectors and base station apparatuses, the range in which the synchronization time shift τ can be detected is −π / m <Δωτ <π / m.
For example, when the cell is divided into three sectors and three codes shifted by 2π / 3 are used, the phase rotation is [0, 0, 0, 0, 0,...], [0, 2 / 3π. , 4 / 3π, 6 / 3π (= 0), 8 / 3π (= 2 / 3π), ...], [0, 4 / 3π, 8 / 3π, 12 / 3π (= 0), 16 / 3π When three orthogonal codes shifted by 2 / 3π as (= 4 / 3π),... Are used as downlink reference signals, downlink reference signals (interfering radio waves) from a plurality of sectors and base station apparatuses are received. , Θ (ω ₁ ) −θ (ω ₂ ) is equal to or greater than π / 3, which is half of the phase difference 2π / 3, and phase rotation caused by a phase shift applied to the downlink reference signal and a synchronization time shift Cannot be identified. Therefore, the range in which the synchronization time shift τ can be detected is −π / 3 <Δωτ <π / 3, and the range in which the synchronization time shift can be corrected using the downlink reference signal is narrowed.
The method for detecting the synchronization time difference τ is the same for a known signal, for example, the synchronization channel SCH.

<Configuration of base station device>
Hereinafter, configurations of the base station apparatuses A1 and A2 (hereinafter referred to as base station apparatus a1) according to the present embodiment will be described.
FIG. 6 is a schematic block diagram illustrating the configuration of the base station apparatus a1 according to this embodiment.
The base station apparatus a1 includes an upper layer a11, a coding unit a12, a modulation unit a13, a transmission unit a14, a control unit a15, a reception unit a16, a demodulation unit a17, and a data processing unit a18. In FIG. 6, only the outline of the configuration related to the description of the present embodiment is shown.

The upper layer a11 comprehensively controls the operation of each unit. The upper layer a11 includes a transmission signal information notification unit a111.
The transmission signal information notification unit a111 transmits the transmission signal information including the type of the downlink reference signal, the DRX cycle, the transmission time of the synchronization channel SCH, and the position information of the paging signal to the coding unit a12, the modulation unit a13, and the transmission unit a14. To the mobile station apparatuses B1 and B2. Here, the type of the downlink reference signal is, for example, “m” when the code used for the downlink reference signal is an orthogonal code using phase rotation and a 2π / m shift code is used. When the orthogonal code using phase rotation is not used, “1” is set.

The encoding unit a12 encodes data such as traffic data and control data input from the upper layer a11 based on transmission control information input from the control unit a15. The control data includes a broadcast information channel, a downlink shared control channel, and the like.
The encoding unit a12 outputs the encoded data to the modulating unit a13.

The modulation unit a13 modulates the data input from the encoding unit a12 based on the transmission control information input from the control unit a15, and outputs the data to the transmission unit a14.
The transmission unit a14 appropriately power-controls the data input from the modulation unit a13 based on the transmission control information input from the control unit a15, and then multiplexes the data with the downlink reference signal and the synchronization channel SCH, and arranges them in the channel And it transmits to mobile station apparatus B1 and B2 via an antenna (not shown).

The control unit a15 outputs the above-described transmission control information included in the control information input from the upper layer a11 to each unit (encoding unit a12, modulation unit a13, and transmission unit a14) related to transmission.
In addition, the control unit a15 outputs the reception control information included in the control information input from the higher layer a11 to each unit (reception unit a16, demodulation unit a17, and data processing unit a18) related to reception.

The receiving unit a16 receives the signals transmitted from the mobile station devices B1 and B2 at the frequency indicated by the reception control information input from the control unit a15 via an antenna (not shown). The reception unit a16 down-converts the received signal into a baseband signal and outputs the signal to the demodulation unit a17.
The demodulation unit a17 demodulates the signal input from the reception unit a16 based on the reception control information input from the control unit a15 and the propagation path estimation result using the uplink reference signal, and the demodulated data is a data processing unit Output to a18.

The data processing unit a18 extracts traffic data and control data from the data input from the demodulation unit a17 and outputs the traffic data and control data to the upper layer a11. The control data includes the quality information (base station device data) of the base station device a1 measured by the mobile station devices B1 and B2, the cell ID of the neighboring cell, the quality information of the neighboring cell, and the neighboring cell. Data related to neighboring peripheral base station devices, such as the type of code used for the downlink reference signal to be used, information indicating whether the cell is a cell that transmits only the MBMS (Multimedia Broadcast Multicast Service) signal (Peripheral base station apparatus data) is included.
For example, the control data in the base station apparatus A1 in FIG. 1 includes data related to the base station apparatus A2 as peripheral base station apparatus data.

<Configuration of mobile station device>
Hereinafter, the configuration of mobile station apparatuses B1 to B3 (hereinafter referred to as mobile station apparatus b1) according to the present embodiment will be described.
FIG. 7 is a schematic block diagram illustrating the configuration of the mobile station apparatus b1 according to this embodiment.
The mobile station device b1 includes an upper layer b11, a coding unit b12, a modulation unit b13, a transmission unit b14, a control unit b15, a reception control unit b16, a reception unit b17, a demodulation unit b18, a synchronization unit b19, a data processing unit b20, and a synchronization A maintenance unit b21 (time shift detection unit) is included. In addition, the transmission signal information receiving unit b111, the detectable cycle storage unit b112, the synchronization maintaining process determining unit b113 (time shift detection signal determining unit), the synchronization correcting unit b114, the receiving control unit b16, the receiving unit b17, and the demodulation of the upper layer b11 The unit b18, the synchronization unit b19, the data processing unit b20, and the synchronization maintaining unit b21 correspond to the reception device E1. FIG. 7 shows only the outline of the configuration related to the description of the present embodiment.

The upper layer b11 comprehensively controls the operation of each unit. The upper layer b11 includes a transmission signal information reception unit b111, a detectable cycle storage unit b112, a synchronization maintenance process determination unit b113, and a synchronization correction unit b114.
The transmission signal information reception unit b111 receives the transmission signal information transmitted from the base station apparatus a1 via the reception unit b17, the demodulation unit b18, and the data processing unit b20. The transmission signal information receiving unit b111 outputs the received transmission signal information to the synchronization maintaining process determining unit b113.

  The detectable cycle storage unit b112 associates the type of the downlink reference signal with the maximum DRX cycle (hereinafter referred to as the maximum detectable DRX cycle) that makes it possible to uniquely detect the synchronization time shift τ for the type of signal. And store in advance.

For example, when the type of code used for the downlink reference signal is an orthogonal code using phase rotation, the maximum detectable DRX cycle T1 [s] corresponding to the type of downlink reference signal (value is other than “1”) is: When the accuracy of the quartz crystal resonator of the timer included in the reception control unit b16 is P [ppm], T1 = τ ₁ / P. Here, tau ₁ is a tau ₁ satisfying Δωτ ₁ = π / m. In this embodiment, T1 when the type of the downlink reference signal is 3 is used. For example, when P = 1.17 ppm, T1 = 1.59 [s].
When the type of code used for the downlink reference signal is not an orthogonal code using phase rotation, the maximum detectable DRX cycle T2 [s] corresponding to the type of downlink reference signal (value is “1”) is received control. When the accuracy of the quartz oscillator of the timer included in the part b16 is P [ppm], T2 = τ ₂ / P. Here, tau ₂ is a tau ₂ satisfying Δωτ ₂ = π. In the present embodiment, for example, when P = 1.17 ppm, T2 = 4.78 [s].

In the present embodiment, the maximum detectable DRX cycle calculated in advance as described above is stored in advance. However, the present invention is not limited to this, and the mobile station device b1 sets the accuracy P of the quartz oscillator of the timer. The maximum detectable DRX cycle may be calculated from P stored in advance, or may be calculated from the measured P by measuring the accuracy P of the quartz oscillator of the timer.
In the present embodiment, the time measurement accuracy is the time measurement accuracy and the accuracy of the quartz crystal unit of the timer. However, the present invention is not limited to this, and correction processing for the reception time count in the mobile station device b1 is performed. It may be time information at the time of execution, or information obtained by adding movement speed information obtained from GPS (Global Positioning System) / Doppler shift amount to the above information, and the maximum value of the synchronization time shift τ Any information can be used as long as it can be calculated.

The synchronization maintaining process determination unit b113 receives the downlink reference signal type, the DRX cycle, the transmission time of the synchronization channel SCH, and the position information of the paging signal as the transmission signal information from the transmission signal information reception unit b111. The synchronization maintaining process determining unit b113 reads out the maximum detectable DRX cycle corresponding to the type of the input downlink reference signal from the detectable cycle storage unit b112, compares it with the input DRX cycle, and will be described later. In b21, a synchronization signal (in this embodiment, a downlink reference signal or a synchronization channel SCH) used for detecting the synchronization time shift τ is determined (hereinafter, the determined synchronization signal is referred to as a time shift detection signal). Details of the method for determining the time shift detection signal will be described later.
The synchronization maintaining process determination unit b113 outputs control information for detecting the synchronization time shift τ using the time shift detection signal to the synchronization maintaining unit b21.

Further, the synchronization maintaining process determination unit b113 outputs the information on the time shift detection signal and the reception timing for receiving the time shift detection signal to the reception control unit b16. Specifically, when the time shift detection signal is a downlink reference signal, the synchronization maintenance process determination unit b113 receives a reception time (hereinafter, intermittent reception time) when the time indicated by the DRX cycle has elapsed since the time when the synchronization process or the resynchronization process was performed. Is output as the reception timing. On the other hand, when the time shift detection signal is the synchronization channel SCH, the synchronization maintaining process determination unit b113 is a reception time of the synchronization channel SCH calculated from the transmission time of the synchronization channel SCH, and is a paging signal indicated by the position information of the paging signal The reception time immediately before the reception timing (hereinafter referred to as SCH reception time before paging) is output as the reception timing.
In addition, the synchronization maintaining process determining unit b113 uses the synchronization channel SCH as a loss of synchronization when a data error continues for a predetermined number of times or more due to error detection such as CRC check of data input from the data processing unit b20. The control information for performing the resynchronization process is output to the control unit b15.

  The synchronization correction unit b114 detects the synchronization time lag τ included in the synchronization signal output from the synchronization maintaining unit b21, and receives control information for correcting the synchronization time lag of the accumulated synchronization time via the control unit b15. Output to. The synchronization correction unit b114 outputs control information for correcting the synchronization time deviation every time a synchronization signal is input from the synchronization maintaining unit b21. For example, when the synchronization time shift τ is detected using the downlink reference signal, control information for correcting the synchronization time shift is output every intermittent reception.

The encoding unit b12 encodes data such as user data, traffic data, and control data input from the upper layer b11 based on transmission control information input from the control unit b15.
The control data includes uplink reference signals, uplink shared control channel data, and the like, and the quality information (base station device data) of the base station device a1 measured by the mobile station device b1, and cell IDs of neighboring cells. , Data related to neighboring base station devices such as quality information of neighboring cells (neighboring base station device data) are included. Also, the transmission control information includes transmission timing and multiplexing method regarding uplink channels, arrangement information of transmission data of each channel, information regarding modulation and transmission power.
The encoding unit b12 outputs the encoded data to the modulating unit b13.

The modulation unit b13 modulates the data input from the encoding unit b12 based on the transmission control information input from the control unit b15, and outputs the modulated data to the transmission unit b14.
The transmission unit b14 appropriately controls the power of the data input from the modulation unit b13 based on the transmission control information input from the control unit b15, and arranges the data in each channel via an antenna (not shown). It transmits to base station apparatus a1.

The control unit b15 outputs the above-described transmission control information included in the control information input from the upper layer b11 to each unit (encoding unit b12, modulation unit b13, and transmission unit b14) related to transmission.
The control unit b15 receives the reception control information included in the control information input from the upper layer b11 (reception control unit b16, reception unit b17, demodulation unit b18, synchronization unit b19, data processing unit b20). , And the synchronization maintaining unit b21). The reception control information includes, for example, information on the frequency at which the transmission signal of the base station apparatus a1 is received, reception time and multiplexing method regarding the downlink channel, arrangement information of reception data of each channel, information on modulation and transmission power.

The reception control unit b16 controls the reception unit b17 to receive the time shift detection signal at the reception time of the reception timing input from the synchronization maintenance process determination unit b113.
Further, the reception control unit b16 measures a time for time synchronization with the reception unit b17. That is, the reception control unit b16 measures the time for time synchronization.

The receiving unit b17 receives the signal transmitted from the base station apparatus a1 through an antenna (not shown) at the frequency indicated by the reception control information input from the control unit b15. The reception unit b17 down-converts the received signal into a baseband signal and outputs the signal to the demodulation unit b18 and the synchronization unit b19.
The receiving unit b17 performs intermittent reception or SCH reception according to the control of the reception control unit b16.
In addition, the receiving unit b17 performs synchronization time deviation correction according to the control information input from the synchronization correcting unit b114 via the control unit b15.

  The demodulator b18 demodulates the OFDM symbol by demodulating the signal input from the receiver b17 based on the reception control information input from the controller b15 and the propagation path estimation result using the downlink reference signal. The symbol data is output to the data processing unit b20. Further, the demodulator b18 outputs the demodulated downlink reference signal to the synchronization maintaining unit b21.

The synchronization unit b19 performs time synchronization and cell ID identification from the synchronization channel SCH input from the reception unit b17. The synchronization unit b19 outputs the synchronization channel SCH to the synchronization maintaining unit b21, and the synchronization unit b19 outputs a synchronization signal as an identification result to the upper layer b11.
The data processing unit b20 extracts traffic data and control data from the data input from the demodulation unit b18 and outputs the traffic data and control data to the upper layer b11.

The synchronization maintaining unit b21 is a downlink reference signal input from the demodulating unit b18 or a synchronization channel input from the synchronizing unit b19 according to the control information output from the synchronization maintaining process determining unit b113 input via the control unit b15. SCH is used to detect a correlation with a downlink reference signal stored in advance or a synchronization channel SCH. The synchronization maintaining unit b21 detects the phase rotation θ (ω ₁ ), θ (ω ₂ ) based on the detected correlation, and the downlink reference signal or the synchronization channel SCH input from the control unit b15 is arranged. Τ is calculated using the subcarrier frequency interval Δω. That is, the synchronization maintaining unit b21 detects the synchronization time difference τ measured by the reception control unit b16 based on the difference between the synchronization signal intermittently received by the reception unit b17 and the synchronization signal stored in advance.

The synchronization maintaining unit b21 receives the synchronization channel SCH indicated by the control information output from the synchronization maintaining process determining unit b113 or the downlink reference signal by the receiving unit b17 and is input via the demodulating unit b18 or the synchronizing unit b19. Every time, the synchronization time shift τ is detected.
The synchronization maintaining unit b21 outputs a synchronization signal including the detected synchronization time difference τ to the upper layer b11.

<Operation of mobile station device>
Hereinafter, the operation of the mobile station apparatus b1 will be described.
FIG. 8 is a flowchart for explaining the operation of the mobile station apparatus b1 according to this embodiment. In addition, before starting the operation | movement of this figure, the mobile station apparatus b1 is a state before performing intermittent reception.
The mobile station apparatus b1 reads the maximum detectable DRX cycles T1 and T2 (S1001). Normally, T1 <T2 is set, but when the accuracy of the crystal resonator of the mobile station device b1 is low, T1 = T2 may be obtained.

  The mobile station apparatus b1 acquires the DRX cycle, paging position information in the frame, and the type of the downlink reference signal from the base station apparatus a1 of the cell in which the mobile station apparatus is located (S1002). Note that the type of the downlink reference signal may be included in the broadcast information broadcast by the base station apparatus a1, and is used for the frame configuration used in the base station apparatus a1 (normal transmission to the mobile station apparatus b1). The type may be identified by using a normal frame configuration and an extended frame configuration used for services such as MBMS.

Next, the mobile station apparatus b1 determines whether or not the type of code used for the downlink reference signal acquired from the base station apparatus a1 is an orthogonal code using phase rotation (S1003).
When it is determined in step 1003 that the type of code used for the downlink reference signal is not an orthogonal code using phase rotation (No), the mobile station apparatus b1 sets the maximum detectable DRX cycle T to T2. (S1004). On the other hand, if it is determined in step S1003 that the type of code used for the downlink reference signal is an orthogonal code using phase rotation (Yes), the mobile station apparatus b1 determines the maximum detectable DRX cycle T. T1 is set (S1005).

Next, the mobile station apparatus b1 determines whether the DRX cycle acquired from the base station apparatus a1 is larger than the maximum detectable DRX cycle T (S1006).
If it is determined in step S1006 that the DRX cycle acquired from the base station apparatus a1 is larger than the maximum detectable DRX cycle T (Yes), the mobile station apparatus b1 stops the reception process and then performs the next reception process. The wake-up time Twa (reception timing) is set as the pre-paging SCH reception time (S1007).
On the other hand, when it is determined in step S1006 that the DRX cycle acquired from the base station apparatus a1 is equal to or less than the maximum detectable DRX cycle T (No), the mobile station apparatus b1 uses the time Twa as the intermittent reception time. (S1008).

The mobile station apparatus b1 stops the reception process and starts measuring with a timer (S1009). The mobile station apparatus b1 determines whether or not the time indicated by the timer is before the time Twa (S1011).
When it is determined in step S1011 that the time indicated by the timer is before the time Twa (Yes), the mobile station apparatus b1 performs the determination process in S1011. On the other hand, when it is determined in step S1011 that the time indicated by the timer is a time after time Twa (No), the mobile station device b1 determines that the DRX cycle acquired from the base station device a1 is It is determined whether or not it is larger than the maximum detectable DRX cycle T determined based on the measurement accuracy of time (S1012).

  If it is determined in step S1012 that the DRX cycle acquired from the base station apparatus a1 is larger than the maximum detectable DRX cycle T (Yes), the mobile station apparatus b1 receives the synchronization channel SCH from the base station apparatus a1. (S1013). The mobile station apparatus b1 performs synchronization maintenance processing using the received synchronization channel SCH (S1014).

On the other hand, when it is determined in step S1012 that the DRX cycle acquired from the base station apparatus a1 is equal to or less than the maximum detectable DRX cycle T (No), the mobile station apparatus b1 determines that the subframe in which paging is to be arranged. Is received, and the synchronization maintaining process is performed using the received downlink reference signal (S1015).
When synchronization maintenance processing is performed using a downlink reference signal, since the downlink reference signal is arranged at the first OFDM symbol of all subframes, the first OFDM symbol of the same subframe as the subframe in which the paging signal is arranged Can be received. In this case, since the downlink reference signal and the paging signal can be received by the same reception process, the power related to reception can be reduced compared to the case where each signal is received individually. Also, since the paging signal can be received immediately after the synchronization maintaining process, the paging signal can be received immediately after the synchronization maintaining process, and an accurate paging signal can be received.

  As described above, according to the present embodiment, the mobile station apparatus b1 is used to detect a time lag to be measured for time synchronization with the base station apparatus a1 based on the time measurement accuracy in the own apparatus. Determine the synchronization signal. Thereby, according to the measurement accuracy of the time of the mobile station apparatus b1, time synchronization can be performed using an appropriate signal that can maintain synchronization, and by reducing the resynchronization process for performing time synchronization again Power consumption can be reduced.

  In the above embodiment, the mobile station device b1 uses the synchronization signal used by the synchronization maintaining unit b21 for detection according to the type of code used for the downlink reference signal used by the base station device a1 in which the mobile station device is located. decide. Furthermore, the mobile station apparatus b1 may determine the synchronization signal used for detection by the synchronization maintaining unit b21 according to the type of code used for the neighboring cell, that is, the downlink reference signal used by the adjacent base station apparatus. .

In this case, in addition to the determination in step S1003 of FIG. 8, the mobile station device b1 includes an orthogonal code using phase rotation in the type of code used for the downlink reference signal used by neighboring cells included in the control data. If the type of code used for the downlink reference signal used by the cell that is located and the neighboring cell includes an orthogonal code using phase rotation, the process of step S1005 is performed.
That is, the mobile station apparatus b1 receives information on the type of code used for the downlink reference signal transmitted by the other base station apparatus a1 adjacent to the base station apparatus a1, and the synchronization maintenance process determination unit b113 receives the received downlink The synchronization maintaining unit b21 determines a synchronization signal used for detection according to whether or not the type of code used for the reference signal is an orthogonal code using phase rotation.

Further, the mobile station apparatus b1 may determine the type of code used for the downlink reference signal based on information indicating whether or not the cell transmits only the MBMS signal. That is, the type of code used for the downlink reference signal is determined based on the type of signal transmitted by the base station apparatus a1.
For example, in a cell that transmits only an MBMS signal, there is a high possibility that the type of code used for the downlink reference signal is an orthogonal code using phase rotation, so the maximum detectable DRX cycle T is set to a short time. Time synchronization can be performed using an appropriate signal capable of maintaining synchronization, and power consumption can be reduced by reducing resynchronization processing for performing time synchronization again.

In the above embodiment, the mobile station apparatus b1 selects the value of the maximum detectable DRX cycle T according to whether or not the type of code used for the downlink reference signal is an orthogonal code using phase rotation. The synchronization maintaining unit b21 determines the synchronization signal used for detection. However, the present invention is not limited to this. For example, even if the value of the maximum detectable DRX cycle T is selected for each 2π / m shift code. Good.
For example, when P = 1.17 ppm, the mobile station apparatus b1 changes to step S1001 in FIG. 8 and sets the maximum detectable DRX cycle T1 corresponding to the 2π / 3 shift code to T1 = 1.59 [s]. , The maximum detectable DRX cycle T3 corresponding to the π / 3 (2π / 6) shift code is T3 = 0.79 [s], and the maximum detectable DRX cycle T2 when not a quadrature code using phase rotation , T2 = 4.78 [s]. Then, the mobile station apparatus b1 determines the type of code used for the downlink reference signal instead of step S1003 in FIG. 8, and changes to steps S1004 and S1005 according to the type of code used for the downlink reference signal. Any one of T1 to T3 is set in the maximum detectable DRX cycle T.

  Moreover, in the said embodiment, although the mobile station apparatus b1 determines with the kind of code | symbol of a downlink reference signal, this invention is not limited to this, The synchronous channel P-SCH uses the orthogonal code | symbol using phase rotation. It is possible to change the values of T1 and T2 depending on whether they are used. Furthermore, when P-SCH of orthogonal code using phase rotation is used, it is possible to widen the range of correction of synchronization deviation by performing synchronization correction processing using only S-SCH.

  Note that a part of the mobile station device b1 in the above-described embodiment, for example, the transmission signal information receiving unit b111, the synchronization maintaining process determining unit b113, the synchronization correcting unit b114, and the synchronization maintaining unit b21 may be realized by a computer. . In that case, a program for realizing the control function is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read by a computer system built in the mobile station apparatus and executed. It may be realized. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” is a medium that dynamically holds a program for a short time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, In such a case, a volatile memory inside a computer system serving as a server or a client may be included, and the one holding a program for a certain period of time may be included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the scope of the present invention. It is possible to

1 is a conceptual diagram of a communication system according to an embodiment of the present invention. It is a flowchart which shows the cell search process which concerns on this embodiment. It is a timing chart explaining the intermittent reception processing concerning this embodiment. It is explanatory drawing explaining the structure of the radio | wireless frame which concerns on this embodiment. It is explanatory drawing explaining arrangement | positioning of the signal which concerns on this embodiment. It is a schematic block diagram explaining the structure of the base station apparatus which concerns on this embodiment. It is a schematic block diagram explaining the structure of the mobile station apparatus which concerns on this embodiment. It is a flowchart explaining operation | movement of the mobile station apparatus which concerns on this embodiment. It is a flowchart which shows the cell search process which concerns on a prior art. It is explanatory drawing explaining the structure of the radio | wireless frame which concerns on a prior art. It is explanatory drawing explaining arrangement | positioning of the signal which concerns on a prior art.

Explanation of symbols

A1, A2, a1 ... base station apparatus, B1 to B3, b1 ... mobile station apparatus a11 ... upper layer, a12 ... encoding part, a13 ... modulation part, a14 ... transmission part , A15 ... control unit, a16 ... reception unit, a17 ... demodulation unit, a18 ... data processing unit, a111 ... transmission signal information notification unit b11 ... upper layer, b12 ... Code part, b13 ... modulation part, b14 ... transmission part, b15 ... control part, b16 ... reception control part, b17 ... reception part, b18 ... demodulation part, b19 ... Synchronization unit, b20 ... data processing unit, b21 ... synchronization maintaining unit (time shift detection unit), b111 ... transmission signal information receiving unit, b112 ... detectable cycle storage unit, b113 ... synchronization Maintenance processing determination unit (time shift detection signal determination unit), b114 ... synchronization correction unit

Claims (8)

In a receiving apparatus that intermittently receives at least two types of synchronization signals used for time synchronization transmitted from a transmitting apparatus,
A reception control unit for measuring time for the time synchronization;
Due to the difference between the intermittently received synchronization signal and the synchronization signal stored in advance, a time shift detection unit that detects a time shift measured by the reception control unit;
A time shift detection signal determination unit that determines the synchronization signal used for detection by the time shift detection unit based on the measurement accuracy of time in the reception control unit and the type of code used for the synchronization signal;
A receiving apparatus comprising: The time lag detection signal determining unit determines the synchronization signal used for detection by the time lag detection unit so that the time lag detection unit can uniquely detect a time lag measured by the reception control unit. The receiving apparatus according to claim 1. Receiving a communication request signal that is transmitted in a subframe that is a transmission interval at which the transmission device transmits a signal;
The at least two types of synchronization signals are a first synchronization signal arranged for each subframe and a second synchronization signal arranged in the predetermined subframe, and are arranged subcarriers A second synchronization signal whose interval is smaller than the interval of the subcarriers in which the first synchronization signal is arranged,
3. The time shift detection signal determination unit prioritizes the first synchronization signal over the second synchronization signal, and uses the time shift detection unit as the synchronization signal used for detection. The receiving device described in 1. The receiving device receives information indicating the type of code used for the synchronization signal transmitted by another transmitting device adjacent to the transmitting device;
The time lag detection signal determination unit is configured to determine whether the time lag detection unit is based on the time measurement accuracy in the reception control unit, the type of code used for the synchronization signal, and the type of code represented by the received information. The receiving apparatus according to claim 1, wherein the synchronization signal used for detection is determined. Information indicating the type of code used for the synchronization signal transmitted by another transmitting device is the type of signal transmitted by the other transmitting device,
The time lag detection signal determination unit is configured to determine the time lag detection unit based on the time measurement accuracy in the reception control unit, the type of code used for the synchronization signal, and the type of signal transmitted by the other transmission device. The receiver according to claim 4, wherein the synchronization signal used for detection is determined. The code used for the synchronization signal includes an orthogonal code using phase rotation,
The receiving apparatus according to claim 1, wherein the type of code used for the synchronization signal includes a type representing the amount of phase rotation. In a reception control method in a receiving apparatus that intermittently receives at least two types of synchronization signals used for time synchronization transmitted from a transmitting apparatus,
A first process in which the receiving device measures time for the time synchronization;
A second process in which the receiver detects a time lag measured in the first process due to a difference between the intermittently received synchronization signal and a previously stored synchronization signal;
The receiver determines the synchronization signal used for detection in the second process based on the time measurement accuracy in the first process and the type of code used for the synchronization signal. And the process
A reception control method comprising: In the computer of the receiving device that intermittently receives at least two types of synchronization signals used for time synchronization transmitted from the transmitting device,
Reception control means for measuring time for the time synchronization;
A time lag detecting means for detecting a time lag measured by the reception control means due to a difference between the intermittently received synchronization signal and a synchronization signal stored in advance;
A time lag detection signal determining means for determining the synchronization signal used for detection by the time lag detecting means based on the measurement accuracy of time in the reception control means and the type of code used for the synchronization signal;
Reception control program to function as.

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