JP2011193537A - Mobile station and communication method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile station that achieves suitable cell search processing, without increasing in scale or complicating a mobile station structure. <P>SOLUTION: A mobile station for communicating with a base station in a mobile communications system which can transmit unicast data and broadcast/multicast data, includes a receiver which receives a cell-specific pilot signal influenced by such the control of a predetermined quantity that a difference between the start phase of a cell-specific pilot signal transmitted in a subframe in which the base station transmits the unicast data, and the start phase of a cell-specific pilot signal transmitted in the following subframe is equal to the difference between the start phase of a cell-specific pilot signal transmitted in a subframe in which the base station transmits the broadcast/multicast data and the start phase of a cell-specific pilot signal transmitted in the next subframe. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a mobile station and a mobile station communication method.

  In a cellular system, generally, a mobile station performs a cell search process for searching for a cell to which a radio link is connected.

  The cell search is performed using a synchronization channel (SCH) included in a downlink radio frame. In addition to the synchronization channel, a cell-specific pilot channel or broadcast information channel (Broadcast Channel, BCH) may be used (Non-patent Document 1). An example of cell search will be described with reference to the drawings.

  FIG. 1 shows an example of the configuration of a radio frame transmitted from a base station transmitter.

  As shown in FIG. 1, the radio frame is configured by multiplexing various channels in a two-dimensional direction of time and frequency. Further, in the example shown in FIG. 1, the radio frame has ten subframes SF1 to SF10 in the time direction, and each subframe SF is composed of two slots of the first half and the second half.

  Further, in each slot, a resource uniquely determined by a symbol position (time) and a subcarrier position (frequency) is called a resource element.

  Here, as various channels multiplexed in the slot, there are a first synchronization channel (P-SCH), a second synchronization channel (S-SCH), and a pilot signal channel (P-CH).

  The first synchronization channel (P-SCH) has a common pattern for all cells, and the last symbol of slot # 0 in the first half of the first subframe SF1 and slot # 10 in the first half of the sixth subframe SF6. Time multiplexed.

  The second synchronization channel (S-SCH) has a unique pattern for the cell ID group, in which the cell IDs assigned to each cell are grouped in advance. The second synchronization channel (S-SCH) is time-multiplexed to the second symbol from the end of each slot # 0 in the first half of the first subframe SF1 and slot # 10 in the first half of the sixth subframe SF6.

  Further, the pilot signal channel (P-CH) has a cell-specific scramble code, which is information specific to the cell, and the first symbol and the fifth symbol of each slot (# 0, # 1, # 2 ...). Time multiplexed.

  Since the cell ID assigned to each cell and the cell-specific scramble code have a one-to-one correspondence, the mobile station specifies the cell-specific scramble code, thereby determining the cell ID of the cell in which it is located. Can be identified.

  For cell-specific scramble codes, use a method that uses a base station-specific pseudo-random sequence multiplied by a phase rotation sequence that is orthogonal between sectors in the same base station, or a method that uses a Generalized Chirp Like sequence as a pseudo-random sequence. Is also possible.

  FIG. 2 shows a cell search processing procedure in the mobile station. When receiving the radio format shown in FIG. 1 from the base station, the mobile station detects the correlation with the replica of the time signal of the first synchronization channel (P-SCH), which is a known pattern, as a first-stage process. The timing indicating the maximum correlation value is set as the subframe timing (step S1).

  As a second stage, fast Fourier transform (FFT) processing is performed at the timing detected in the first stage to convert it to a frequency domain signal, and a second synchronization channel (S-SCH) is extracted from the signal. Then, the correlation between the extracted second synchronization channel (S-SCH) and the candidate second synchronization channel sequence replica is taken, for example, the candidate second synchronization channel sequence showing the maximum correlation value is set as the detected second synchronization channel sequence . A cell ID group is identified from the detected second synchronization channel (step S2).

  Next, as a third stage, fast Fourier transform (FFT) processing is performed at the timing detected in the first stage to convert it into a frequency domain signal, and a pilot signal channel (P-CH) is extracted from the signal. Then, a correlation between the extracted pilot signal channel (P-CH) and the scramble code replica corresponding to the candidate cell ID included in the cell ID group detected in the second stage is obtained, for example, a candidate scramble code indicating the maximum correlation value The cell ID corresponding to is set as the detected cell ID (step S3). Thereby, the cell in the area is specified.

  By the way, in 3GPP (3rd Generation Partnership Project), the specification of multimedia broadcast / multicast communication service (MBMS: Multimedia Broadcast / Multicast Service) is being studied for standardization of next-generation mobile phone communication.

  For example, MBMS data is time-multiplexed with unicast data in subframe units. In Non-Patent Document 1, a guard interval longer than the guard interval used for unicast data is used, and the same data is transmitted from a plurality of cells at the same timing and the same frequency. Describes how to combine and improve reception quality.

  This is called a single frequency network. In this case, the same cell common pilot signal is transmitted between cells in order to demodulate the same MBMS data transmitted from a plurality of cells.

  In Non-Patent Document 2, a unicast control signal is multiplexed in a subframe assigned to MBMS data (hereinafter referred to as an MBMS subframe). For demodulation of the unicast control signal and CQI measurement, It is described that cell-specific pilot signals having different patterns between unicast cells are multiplexed in an MBMS subframe.

  The pilot signal configuration of the MBMS subframe is also described in Non-Patent Document 3. According to this configuration, in the MBMS subframe, a cell-specific pilot signal for unicast is multiplexed only on the first symbol.

  When MBMS subframes are time-multiplexed as described above, subframes having different guard interval lengths are time-multiplexed. In the initial cell search performed when the mobile station is powered on, there is no information about the guard interval length of the received subframe, so a problem occurs in the third stage of cell search.

  This problem is described in detail in Non-Patent Document 4. As a means for solving this problem, as described in Non-Patent Document 4, there is a method of devising a method for adding a guard interval of an MBMS subframe. Further, as described in Non-Patent Document 5, there is a method of using only a pilot signal in a subframe in which a synchronization channel is multiplexed at the time of initial cell search.

3GPP TR25.814 V7.0.0 3GPP TSG-RAN WG1, R1-060372, “Multiplexing of Unicast Pilot and Control Channels in E-MBMS for EUTRA Downlink”, Texas Instruments 3GPP TSG-RAN WG1, R1-070383, “Reference Signals for Mixed Carrier MBMS”, Nokia 3GPP TSG-RAN WG1, R1-060563, “Channel Design and Long CP Sub-frame Structure for Initial Cell Search”, Fujitsu 3GPP TSG RAN WG1, R1-063304 “Three-Step Cell Search Method for E-UTRA”, NTT DoCoMo, Institute for Infocomm Research, Mitsubishi Electric, Panasonic, Toshiba Corporation

  Here, when MBMS subframes are multiplexed in a radio frame, the number of resource elements of the cell-specific pilot signal in one radio frame is smaller than when all radio frames are assigned by unicast subframes (this relationship). May be the opposite case.)

  Further, the number of resource elements of the cell-specific pilot signal in one radio frame depends on how many MBMS subframes are multiplexed. For example, if the cycle of the scramble code of the cell-specific pilot signal is one radio frame, the phase of the scramble code at each transmission timing of the cell-specific pilot signal is changed by multiplexing the MBMS subframe.

Figure 3 shows that all subframes in a radio frame are assigned to unicast case 1 (case 1) and subframes # 1 and # 4 are assigned to MBMS case 2 (case 2)
Is illustrated as an example.

  In FIG. 3, the column of “cell-specific scramble code phase” indicates that the cell-specific scramble code is a cell-specific pilot signal and is arranged from the low-frequency resource elements allocated to the cell-specific pilot signal. The phase of the cell scramble code assigned to the resource element on the lowest frequency side at each signal transmission timing is shown.

  Further, the number of resource elements allocated to the cell-specific pilot signal per symbol of the cell-specific pilot signal is Np.

  In Case 1, since all subframes are assigned to unicast, there is no phase shift of the cell-specific scramble code.

  On the other hand, in case 2, since subframes # 1 and # 4 are allocated to MBMS, a phase shift of the cell-specific scramble code occurs.

  As shown in Non-Patent Document 5, even when using the cell-specific pilot signals of subframes # 0 and # 5 in which synchronization channels are multiplexed and taking a correlation, the phase shift of the cell-specific scramble code occurs. If this is the case, the phase of the cell-specific pilot signal in subframe # 5 is unknown, so blind detection or the like must be performed, resulting in an increase in processing amount and a deterioration in detection probability.

  Accordingly, an object of the present invention is to facilitate correlation detection in a mobile station. It is another object of the present invention to make the change amount of the pilot signal transmission start phase between (sub) frames a predetermined amount.

  In addition, when unicast data and MBMS subframes are multiplexed in a radio frame, correlation processing can be performed without causing a phase shift of the cell specific scramble code at each timing of the cell specific pilot signal symbol. Accordingly, it is an object of the present invention to provide a mobile station and a mobile station communication method capable of realizing an appropriate cell search process without increasing or complicating the configuration of the mobile station.

  In order to achieve the above object, the present invention is characterized by using a transmission processing method and a base station in the following mobile communication system. That is, a base station and a mobile station that performs radio communication with the base station in a cell that is a radio communication area formed by the base station, and unicast data as downlink data from the base station to the mobile station, In a cell-specific pilot signal transmission method in a mobile communication system capable of transmitting broadcast / multicast data mixedly, the base station transmits a start phase of a cell-specific pilot signal transmitted in a subframe in which the unicast data is transmitted. The difference between the start phase of the cell-specific pilot signal transmitted in the next subframe, the start phase of the cell-specific pilot signal transmitted in the subframe in which the broadcast / multicast data was transmitted, and the transmission in the next subframe Start of cell specific pilot signal to perform And the difference between the phase the same.

  Furthermore, the base station according to the present invention transmits the unicast data in a base station that forms a radio communication area for communicating with the mobile station in a mobile communication system capable of transmitting unicast data and broadcast / multicast data together. The transmission is performed in the subframe in which the broadcast / multicast data is transmitted, and the difference between the start phase of the cell-specific pilot signal transmitted in the transmitted subframe and the start phase of the cell-specific pilot signal transmitted in the next subframe. A phase control unit that performs control to make the difference between the start phase of the cell-specific pilot signal and the start phase of the cell-specific pilot signal to be transmitted in the next subframe the same.

  According to the present invention having the above characteristics, in a system in which unicast data and MBMS data are mixedly transmitted as downlink data, depending on the number of MBMS subframes allocated in the radio frame, Even when the number of resource elements allocated to a cell-specific pilot signal in a radio frame changes, correlation processing is always performed without causing a phase shift of the cell-specific scrambling code at each timing of the cell-specific pilot signal symbol. Can do.

  Therefore, it is possible to realize an appropriate cell search process without increasing the size or complexity of the mobile station, simplifying the mobile station, and improving the characteristics during the cell search process. Therefore, it is considered extremely useful in the mobile communication field.

An example of the structure of the radio | wireless frame transmitted from the base station transmission apparatus is shown. It is a figure which shows the cell search processing procedure in a mobile station. It is a figure which shows as an example the case where all the sub-frames in a radio | wireless frame are allocated to unicast, and the case where a sub-frame is allocated to MBMS. It is a block diagram which shows the principal part structure of the base station transmitter according to this invention. It is a figure which shows an example of the radio | wireless frame structure expressed in two dimensions of time and a frequency containing a MBMS sub-frame. It is a figure which shows the example controlled by the phase control part so that the phase of a cell specific scramble code may become the same in the symbol of each cell specific pilot signal. It is a block diagram which shows the structure of the principal part of the mobile station in an OFDM communication system. It is a figure explaining a 2nd Example. It is a figure which shows the phase of the cell specific pilot signal in each frequency band in a 2nd Example. It is a figure which shows the structural example of a radio | wireless frame according to a 3rd Example. It is a figure which shows the example of another radio frame according to a 3rd Example.

  Embodiments of the present invention will be described below with reference to the drawings.

[First embodiment]
FIG. 4 is a block diagram showing a main configuration of the base station transmission apparatus according to the present invention.

  4 includes a data selection unit 1, a cell-specific pilot signal channel sequence storage unit 2, a cell common pilot signal sequence storage unit 3, a pilot signal selection unit 4, a phase control unit 5, and a first synchronization channel storage. 6, a second synchronization channel storage unit 7, a channel multiplexing unit 8, a serial / parallel conversion processing unit 9, an IFFT processing unit 10, a guard interval (GI) insertion unit 11, a radio processing unit 12, and a transmission antenna 13. It is configured.

  The data selection unit 1 selects unicast data A or MBMS data B according to scheduling, and sends data for one subframe to the channel multiplexing unit 8. When MBMS data B is selected in the data selection unit 1, a phase control instruction is issued to the phase control unit 5.

The pilot signal selection unit 4 changes the selection method of the cell specific pilot signal channel sequence AA or the cell common pilot signal channel sequence AB according to the type of transmission data of the subframe, and the pilot signal is selected from the corresponding storage unit 2 or 3. Read the signal. When the data type is MBMS, the cell specific pilot signal N _{s_m for 1} MBMS subframe and the cell common pilot signal N _common for 1 MBMS subframe are stored in the cell specific pilot signal channel sequence storage unit 2 and the cell common pilot signal channel, respectively. Read from the series storage unit 3. When the data type is unicast data, cell specific pilot signals N _{s_u} for one unicast subframe are read out.

  At that time, the current phases of the cell-specific pilot signal channel sequence storage unit 2 and the cell common pilot signal channel sequence storage unit 3 are advanced by the read phase.

If the phase control unit 5 there is an instruction of the phase control, the current (phase amount corresponding to N _{S_U)} the phase of the cell-specific pilot signal channel sequence storage unit 2 - advanced by (phase amount corresponding to N _{S_M).}

  That is, the difference between the start phase of the cell-specific pilot signal transmitted in the subframe in which unicast data was transmitted and the start phase of the cell-specific pilot signal transmitted in the next subframe, and the broadcast / multicast data are transmitted. Phase control is performed so that the difference between the start phase of the cell-specific pilot signal transmitted in the subframe and the start phase of the cell-specific pilot signal transmitted in the next subframe is the same.

In other words, in a pilot signal (for example, cell-specific pilot signal) transmission method in a mobile communication system having a base station and a mobile station that performs radio communication with the base station in a cell that is a radio communication area formed by the base station, The difference between the transmission start phase of the pilot signal to be transmitted and the transmission end phase is a first unit transmission period (for example, a subframe for transmitting unicast data) and a second unit transmission period (for example, transmitting MBMS data). The base station transmits the pilot signal transmission start phase in the first unit transmission period and the pilot signal transmission start in the second unit transmission period. The difference from the phase is controlled to a predetermined difference larger than the difference between the transmission start phase and the transmission end phase (first In the example, (phase amount corresponding to N _{S_U)} - is to was adjusted to advance only the phase (phase amount corresponding to _N s_m)).

  Here, the channel multiplexing unit 8 multiplexes each channel signal (modulated data) of various channels (data channel, pilot signal channel, synchronization channel, etc.) to be transmitted to the mobile station UE (User Equipment). / Parallel conversion processing unit 9 (hereinafter sometimes abbreviated as S / P conversion processing unit) performs serial / parallel conversion on the signals (Nc modulation data) multiplexed by the channel multiplexing unit 8 and converts each of them. It is arranged (mapped) on each subcarrier.

  FIG. 5 shows an example of a radio frame configuration that includes MBMS subframes and is expressed in two dimensions of time and frequency. As an embodiment, one radio frame (RF) is composed of 10 subframes (SF), and one subframe is composed of 2 slots (SL).

  One slot is composed of 7 symbols (SB) in the case of a unicast subframe, and is composed of 6 symbols in the case of the MBMS subframe 100 because the guard interval is long.

  The cell-specific pilot signal AA is multiplexed at the first symbol a and the fifth symbol b of each slot of the unicast subframe at intervals of 6 subcarriers. However, the frequency direction arrangement of the fifth symbol b is an arrangement shifted by 3 subcarriers with respect to the frequency arrangement of the first symbol a.

  On the other hand, in the case of MBMS subframe 100, cell-specific pilot signal AA is multiplexed only at the first symbol c of the first half slot at intervals of 6 subcarriers.

  Cell common pilot signal AB is arranged at intervals of 2 subcarriers in second symbol d and fifth symbol e of each slot of MBMS subframe 100. However, the frequency direction arrangement of the fifth symbol is an arrangement shifted by one subcarrier with respect to the frequency direction arrangement of the second symbol.

  However, the cell-specific scramble code transmitted as the cell-specific pilot signal channel AA is controlled by the phase control unit 5 so that the start phase difference of the cell-specific pilot signal between subframes becomes a predetermined amount. An example is shown in FIG.

  In FIG. 6, the first subframe SF (# 1) and the third subframe (# 3) of the radio frame are assigned to unicast, and the second subframe (# 2) is assigned to MBMS. (Hereafter, the Xth subframe is referred to as a subframe (#X)).

The number of resource elements allocated to the cell-specific pilot signal channel per each cell-specific pilot signal symbol is Np. In the example shown in FIG. 6, because 1 cell-specific pilot signal symbols per unicast sub-frame is set to _4, N s_u = 4Np, cell-specific pilot signal symbols per 1MBMS subframe since 1, N _{S_U} = Np It is.

  A cell-specific scramble code is allocated from the low frequency side to the resource element assigned to the cell-specific pilot signal of the cell-specific pilot signal symbol transmitted first in the radio frame.

  In the subframe (# 2) allocated to MBMS, the cell-specific pilot signal is multiplexed only in the first symbol of the first half slot. Therefore, the cell specific scramble code assigned to the lowest frequency side of the next cell specific pilot signal is advanced by 3Np by the phase control unit 5, and becomes P (8Np).

  Similarly, each time an MBMS subframe is multiplexed, the phase of the cell-specific scramble code is advanced. As a result, the phase of the first cell-specific pilot signal symbol in each subframe is determined regardless of the presence or absence of the MBMS subframe in the radio frame.

  Returning to FIG. 4, the IFFT processing unit 10 performs IFFT processing on the modulation data arranged on each subcarrier in units of Nc corresponding to Nc subcarriers, and converts them into a time domain signal.

  The guard interval insertion unit 11 inserts a guard interval for the time domain signal.

  The radio processing unit 12 performs necessary radio processing such as frequency conversion (up-conversion) of the signal after insertion of the guard interval into a predetermined radio signal, and the radio signal is transmitted to the propagation path through the transmission antenna 13.

  Next, the configuration and operation of the mobile station corresponding to the base station described above will be described.

  FIG. 7 is a block diagram showing a configuration of a main part of a mobile station in the OFDM communication system. The mobile station shown in FIG. 7 includes, for example, a receiving antenna unit 20, a radio processing unit 21, a first stage processing unit 200, a second stage processing unit 210, a third stage processing unit 220, a guard interval removal unit 22, and an FFT. A processing unit 23 is provided.

  The first stage processing unit 200 includes a first synchronization channel replica signal storage unit 201, a correlation processing unit 202, a time averaging unit 203, and a subframe timing detection unit 204. The second stage processing unit 210 includes a second synchronization channel extraction unit 211, a correlation processing unit 212, a candidate second synchronization code storage unit 213, a time averaging unit 214, and a second synchronization code radio frame timing detection unit 215. . Further, the third stage processing unit 220 includes a cell specific pilot signal channel extraction unit 221, a candidate cell specific scramble code storage unit 222, a phase control unit 223, a correlation processing unit 224, a time averaging unit 225, and a cell specific scramble code detection unit 226. have.

  Below, the reception process of the mobile station by the said structure is demonstrated.

  Here, the receiving antenna unit 20 receives a radio signal from the base station BS described above, and the radio processing unit 21 performs necessary radio reception processing such as down-conversion processing on the radio signal received by the receiving antenna unit 20. Apply.

  As the first stage processing of the cell search by the first stage processing unit 200, the subframe is based on the correlation between the received signal from the radio processing unit 21 and the replica signal of the first synchronization channel (P-SCH) which is a known pattern. Timing is detected synchronously (FIG. 2: step S1).

  Therefore, in the first stage processing unit 200, the first synchronization channel replica signal storage unit 201 stores the first synchronization channel replica signal in advance, and the correlation processing unit 202 performs first synchronization with the received signal. The correlation with the replica signal stored in the channel replica signal storage unit 201 is obtained.

  The correlation processing result by the correlation processing unit 202 is time averaged by the time averaging unit 203 and input to the subframe timing detection unit 204. The subframe timing detection unit 204 detects the subframe timing of the received signal based on the correlation processing result by the correlation processing unit 202. For example, the timing showing the maximum correlation can be detected as the subframe timing.

  The second stage processing unit 210 performs fast Fourier transform (FFT) based on the subframe timing detected by the first stage processing unit 200 as described above as the second stage processing of the cell search (FIG. 2: step S2). Processing is performed to extract the second synchronization channel and detect the second synchronization code and frame timing.

  Therefore, the guard interval removal unit 22 is inserted into the received signal that is wirelessly processed by the reception processing unit 21 based on the subframe timing detected by the subframe timing detection unit 204 of the first stage processing unit 200. Remove.

  The FFT processing unit 23 performs FFT processing on the effective symbol after removal of the guard interval for a predetermined time interval (at least effective symbol long time), that is, FFT window, thereby converting the time domain received signal into a frequency domain signal. Convert.

  The second synchronization channel extraction unit 211 extracts a resource element in which the second synchronization channel is multiplexed from the frequency domain signal after the FFT processing by the FFT processing unit 23. On the other hand, the candidate second synchronization code used for the correlation processing in the correlation processing unit 212 is stored in the second synchronization code storage unit 213 in advance. The correlation processing unit 212 correlates the second synchronization channel extracted by the second synchronization channel extraction unit 211 and the candidate second synchronization code stored in the candidate second synchronization code storage unit 213.

  The output of the correlation processing unit 212 is averaged by the time averaging unit 214, and the second synchronization code radio frame timing detection unit 215 calculates the second synchronization code and the radio frame timing based on the correlation processing result by the correlation processing unit 212. To detect. For example, the candidate second synchronization code showing the maximum correlation can be used as the detected second synchronization code. Thereby, a cell group is identified.

The third stage processing unit 220 performs cell-specific pilot signal detection processing (FIG. 2: step S3), and the received signal after the FFT processing is the cell-specific pilot signal channel extraction unit 22.
1 is input. The cell specific pilot signal channel extraction unit 221 extracts a resource element in which a cell specific pilot signal is multiplexed from the frequency domain signal after the FFT processing by the FFT processing unit 23.

  The candidate cell-specific scramble code storage unit 222 stores in advance a replica of the candidate cell-specific scramble code used for the correlation processing in the correlation processing unit 224.

  The correlation processing unit 224 correlates the cell specific pilot signal extracted by the cell specific pilot signal channel extraction unit 221 and the candidate cell specific scramble code replica stored in the candidate cell specific scramble code storage unit 222.

  The output of the correlation processing unit 224 is time-averaged by the time averaging unit 225, and the cell-specific scramble code detection unit 226 detects the cell-specific scramble code based on the correlation processing result in the correlation processing unit 224. For example, a candidate cell specific scramble code showing the maximum correlation can be used as a detected cell specific scramble code. Thereby, the cell in which the mobile station is located is specified as a result of the cell search.

[Second Embodiment]
The second embodiment is an example in which the application of the first embodiment is applied to a system in which a downlink signal can be transmitted using any one of a plurality of frequency bands. The configuration example of the base station and the configuration of the mobile station are basically the same as the configurations shown in FIGS. 4 and 7 described above.

  FIG. 8 is a diagram for explaining the second embodiment, where I has 1200 subcarriers as a frequency band, II has 600 subcarriers, II has 300 subcarriers, and III has 144 subcarriers. This is an example of the case V having IV and 72 subcarriers.

  As a feature, in any of the frequency bands I to V having the plurality of subcarriers, the synchronization channel SCH is transmitted with a bandwidth W equal to the minimum frequency band of 72 subcarriers at the center.

  FIG. 9 shows the phase of the cell-specific pilot signal in each frequency band in the second embodiment. Even when MBMS subframes are multiplexed, the phase of each transmission timing of the cell-specific pilot signal is adjusted by the phase controller 5 (see FIG. 4) as shown in FIG.

  Further, the phase of the cell specific pilot signal is always the same in the band W of the center 72 subcarrier regardless of the frequency band.

  Here, in the initial cell search, since the frequency band of the received signal is unknown, only the signal having the bandwidth W equal to the minimum frequency band is received and the cell search is performed. In the wireless processing unit 21, an analog filter or the like is used to receive a signal having a bandwidth equal to the minimum frequency band. This may be performed after the wireless processing unit 21 using a digital filter. Or you may do both.

  The cell search first stage S1 and second stage S2 described in detail in the first embodiment are performed to detect the subframe timing, the cell ID group, and the radio frame timing. As described above, since the synchronization channel SCH is transmitted with a bandwidth W equal to the minimum frequency band at the center of the frequency band in any frequency band, it is not necessary to know which frequency band it is. The cell search first stage S1 and the second stage S2 can be performed using the synchronization channel SCH.

  Subsequently, the cell search third step S3 described in detail in the first embodiment is performed to detect a cell-specific scramble code. At this time, the phase at each transmission timing of the cell-specific pilot signal does not depend on which one is in the frequency band, and does not depend on whether the MBMS subframe is multiplexed. Even if it is not known, the cell-specific scramble code can be detected without causing a phase shift of the cell-specific pilot signal due to MBMS subframe multiplexing.

[Third embodiment]
The third embodiment is also applied on the premise of the first embodiment, and the configurations of the base station transmitting apparatus and the mobile station are the same as those described in the first embodiment.

  In the third embodiment, the cell-specific pilot signal in the MBMS subframe is transmitted only in a limited part of the band.

  This is a configuration applicable to a case where a unicast control signal is transmitted only in a limited band in an MBMS subframe.

  FIG. 10 shows a configuration example of a radio frame according to the third embodiment. That is, in the example shown in FIG. 10, subframes # 0 and # 2 are unicast subframes, and subframe # 1 is an MBMS subframe. In the MBMS subframe, the cell-specific pilot signal is multiplexed only on the center four subcarriers at the head of the subframe.

  The phase control unit 5 advances the 19th phase of subframe # 0 by 4, and sets the phase of the first cell-specific pilot signal to 23 in subframe # 1. Further, the 26th phase of subframe # 1 is advanced by 14, and the phase of the first cell-specific pilot signal is set to 40 in subframe # 2. As a result, the phase of the cell specific pilot signal can be made continuous in subframes # 0, # 1, and # 2.

  FIG. 11 is an example of another radio frame according to the third embodiment. The phase of the first cell specific pilot signal in subframe # 1 is set to 20, and the phase is continuous with the phase of the cell specific pilot signal in subframe # 0. At this time, phase control is performed so that the phase of the cell-specific pilot signal is advanced by 17 in order to continue from subframe # 1 to # 2.

(Appendix 1)
A base station and a mobile station that performs radio communication with the base station in a cell that is a radio communication area formed by the base station. As downlink data from the base station to the mobile station, unicast data and broadcast In a cell-specific pilot signal transmission method in a mobile communication system capable of transmitting mixed multicast data,
A difference between a start phase of a cell-specific pilot signal transmitted in a subframe in which the base station has transmitted the unicast data and a start phase of a cell-specific pilot signal transmitted in a next subframe;
A difference between a start phase of a cell-specific pilot signal transmitted in a subframe in which the broadcast / multicast data is transmitted and a start phase of a cell-specific pilot signal transmitted in a next subframe;
Are the same,
A cell-specific pilot signal transmission method.

(Appendix 2)
In Appendix 1,
A transmission start position in the next subframe of a cell-specific pilot signal to be transmitted in a subframe next to the subframe in which the unicast data is transmitted, and a subframe next to the subframe in which the broadcast / multicast data is transmitted The transmission start position in the next subframe of the cell-specific pilot signal to be transmitted is the same in FIG.
A cell-specific pilot signal transmission method.

(Appendix 3)
In a pilot signal transmission method in a mobile communication system having a base station and a mobile station that performs radio communication with the base station in a cell that is a radio communication area formed by the base station,
When the difference between the transmission start phase and the transmission end phase of the pilot signal to be transmitted can be different between the first unit transmission period and the second unit transmission period,
The base station determines the difference between the transmission start phase of the pilot signal in the first unit transmission period and the transmission start phase of the pilot signal in the second unit transmission period as the transmission start phase and the transmission end. Control to a predetermined difference greater than the difference from the phase,
A cell-specific pilot signal transmission method.

(Appendix 4)
In a base station that forms a wireless communication area that communicates with a mobile station in a mobile communication system that can transmit unicast data and broadcast / multicast data together,
A difference between a start phase of a cell-specific pilot signal transmitted in a subframe in which the unicast data is transmitted and a start phase of a cell-specific pilot signal transmitted in a next subframe;
A difference between a start phase of a cell-specific pilot signal transmitted in a subframe in which the broadcast / multicast data is transmitted and a start phase of a cell-specific pilot signal transmitted in a next subframe;
A phase control unit for performing the same control,
A base station in a mobile communication system comprising:

(Appendix 5)
In a mobile communication station that communicates with a base station that forms a wireless communication area in a mobile communication system that can transmit unicast data and broadcast / multicast data together,
In the base station, the difference between the start phase of the cell-specific pilot signal transmitted in the subframe in which the unicast data is transmitted and the start phase of the cell-specific pilot signal transmitted in the next subframe, and the broadcast / multicast Cells that have been controlled to have the same predetermined amount as the difference between the start phase of the cell-specific pilot signal transmitted in the subframe in which data was transmitted and the start phase of the cell-specific pilot signal transmitted in the next subframe A receiver for receiving the unique pilot signal;
A phase control unit for controlling the phase of the cell-specific pilot signal used for calculating the correlation with the received cell-specific pilot signal based on the phase calculated according to the position of the received subframe in the radio frame;
A mobile station in a mobile communication system, comprising:

(Appendix 6)
A base station and a mobile station that performs radio communication with the base station in a cell that is a radio communication area formed by the base station. As downlink data from the base station to the mobile station, unicast data and broadcast A mobile communication system capable of transmitting mixed multicast data,
A difference between a start phase of a cell-specific pilot signal transmitted in a subframe in which the base station has transmitted the unicast data and a start phase of a cell-specific pilot signal transmitted in a next subframe;
A phase control unit for making the difference between the start phase of the cell-specific pilot signal transmitted in the subframe in which the broadcast / multicast data is transmitted and the start phase of the cell-specific pilot signal transmitted in the next subframe the same With
The mobile station
A phase control unit for controlling the phase of the cell-specific pilot signal used for calculating the correlation with the received cell-specific pilot signal based on the phase calculated according to the position of the received subframe in the radio frame;
A mobile communication system comprising:

(Appendix 7)
In Appendix 6,
The subframe is multiplexed with a different number of subcarriers using one of a plurality of frequency bands, and the phase control unit in the base station supports a synchronization channel in the narrowest frequency band among the plurality of frequency bands. A mobile communication system, wherein phase control is performed so that a band to be matched coincides with a center of each of the plurality of frequency bands.

(Appendix 8)
In Appendix 6,
The cell-specific pilot signal in the subframe to which the broadcast / multicast data is allocated is transmitted only in a limited part of the band, and the phase control unit detects the phase shift from the limited part of the band, A mobile communication system configured to advance a phase of a cell-specific pilot signal in a subframe.

1 Data Selection Unit 2 Cell Specific Pilot Signal Channel Sequence Storage Unit 3 Cell Common Pilot Signal Channel Sequence Storage Unit 4 Pilot Signal Selection Unit 5 Phase Control Unit 6 First Synchronization Channel Storage Unit 7 Second Synchronization Channel Storage Unit 8 Channel Multiplexing Unit 9 Serial / parallel conversion processing unit 10 IFFT processing unit 11 Guard interval insertion unit 12 Radio processing unit 13 Transmitting antenna 20 Reception antenna 21 Radio processing unit 22 Guard interval removal unit 23 FFT processing unit 200 First stage processing unit 210 Second stage processing unit 220 Third stage processing section

Claims (2)

In a mobile station communicating with a base station in a mobile communication system capable of transmitting unicast data and broadcast / multicast data,
In the base station, the difference between the start phase of the cell-specific pilot signal transmitted in the subframe in which the unicast data is transmitted and the start phase of the cell-specific pilot signal transmitted in the next subframe, and the broadcast / multicast Cells that have been controlled to have the same predetermined amount as the difference between the start phase of the cell-specific pilot signal transmitted in the subframe in which data was transmitted and the start phase of the cell-specific pilot signal transmitted in the next subframe A mobile station comprising a receiving unit for receiving a specific pilot signal. In a mobile station communication method for communicating with a base station in a mobile communication system capable of transmitting unicast data and broadcast / multicast data,
In the base station, the difference between the start phase of the cell-specific pilot signal transmitted in the subframe in which the unicast data is transmitted and the start phase of the cell-specific pilot signal transmitted in the next subframe, and the broadcast / multicast Cells that have been controlled to have the same predetermined amount as the difference between the start phase of the cell-specific pilot signal transmitted in the subframe in which data was transmitted and the start phase of the cell-specific pilot signal transmitted in the next subframe A mobile station communication method characterized by receiving a specific pilot signal.

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