JP5150754B2 - Base station apparatus and synchronization channel transmission method - Google Patents

Description

  The present invention relates to a radio communication system to which orthogonal frequency division multiplexing OFDM (Orthogonal Frequency Division Multiplexing) is applied in the downlink, and more particularly to a base station apparatus, a mobile station apparatus, and a synchronization channel transmission method.

  Long Term Evolution (LTE) has been studied by W-CDMA standardization organization 3GPP as a successor to W-CDMA and HSDPA, and as a radio access system, downlink is OFDM and uplink SC-FDMA (Single-Carrier Frequency Multiple Access) has been studied (see, for example, Non-Patent Document 1).

  OFDM is a method in which a frequency band is divided into a plurality of narrow frequency bands (subcarriers) and data is transmitted on each frequency band, and the subcarriers interfere with each other even though they partially overlap on the frequency. By arranging them closely, it is possible to achieve high-speed transmission and increase frequency utilization efficiency.

  SC-FDMA is a transmission method that can reduce interference between terminals by dividing a frequency band and performing transmission using different frequency bands among a plurality of terminals. Since SC-FDMA has a feature that fluctuations in transmission power are reduced, it is possible to realize low power consumption and wide coverage of a terminal.

  In LTE, two types of CPs, Long CP and Short CP, having different lengths are prepared as cyclic prefix (CP) for reducing the influence of intersymbol interference caused by delay waves in OFDM. For example, the Long CP is applied to a cell having a large cell radius, and is applied when an MBMS (Multimedia Broadcast Multicast Service) signal is transmitted, and the Short CP is applied to a cell having a small cell radius. When the Long CP is applied, the number of OFDM symbols in one slot is 6, and when the Short CP is applied, the number of OFDM symbols in one slot is 7.

  By the way, in general, in a wireless communication system using W-CDMA, LTE, or the like, a mobile station is based on a synchronization signal or the like at power-on, standby, communication, or intermittent reception during communication. Therefore, it is necessary to detect a cell having good radio quality for the local station. This process is called cell search in the sense of searching for a cell to which a radio link is to be connected. The cell search method is generally determined based on the time required for the cell search and the processing load on the mobile station when performing the cell search. That is, the cell search method must be a method in which the time required for the cell search is short and the processing load on the mobile station when performing the cell search is small.

  In W-CDMA, cell search is performed using two types of synchronization signals, Primary SCH (P-SCH) and Secondary SCH (S-SCH). Similarly, in LTE, P- The use of two types of synchronization signals, SCH and S-SCH, has been studied.

  For example, as a cell search method, a cell search method for transmitting a P-SCH having one sequence and an S-SCH having a plurality of sequences at a time interval of once every 5 ms has been studied (Non-Patent Document). 2). In the above method, downlink reception timing from each cell is specified by P-SCH, and reception frame timing detection and cell ID or cell group (Group ID) are detected by S-SCH transmitted in the same subframe. ) And the like are specified. Here, for the demodulation and decoding of the S-SCH, it is generally possible to use a channel estimation value obtained from the P-SCH. When cell IDs are grouped, the cell IDs are detected from the cell IDs belonging to the group IDs of the detected cells. For example, the cell ID is calculated based on the signal pattern of the pilot signal. For example, the cell ID is calculated based on the P-SCH and the demodulation / decoding of the S-SCH. Alternatively, the cell ID may be included as an information element of the S-SCH without grouping the cell IDs. In this case, the mobile station can detect the cell ID when the S-SCH is demodulated and decoded.

  However, when the cell search method is applied, in an inter-station synchronization system in which signals from each cell are synchronized, based on a channel estimation value obtained from P-SCHs transmitted in the same sequence from a plurality of cells. Since S-SCH transmitted in different sequences from a plurality of cells is demodulated and decoded, there is a problem that the transmission characteristics of S-SCH deteriorates. Here, the transmission characteristics include, for example, the time required for cell search. In the case of a non-stationary synchronization system in which signals from each cell are not synchronized, the reception timing of the P-SCH sequence transmitted from a plurality of cells differs among the plurality of cells. No problem arises.

  In order to prevent the deterioration of S-SCH characteristics in the inter-station synchronization system as described above, a cell search method in which the number of P-SCH sequences is 1 to 2 or more, for example, 3 or 7, has been studied. (Non-Patent Document 3). Alternatively, a method of transmitting P-SCH at different transmission intervals for each cell has been proposed in order to prevent S-SCH characteristic deterioration in the inter-station synchronization system as described above (Non-Patent Document 4). In the above-described method, P-SCH having different reception timings from a plurality of cells can be used in S-SCH demodulation / decoding, so that it is possible to prevent the above-described deterioration of S-SCH characteristics.

  By the way, it is considered that the larger the number of P-SCH sequences in Non-Patent Document 3 and the type of P-SCH transmission interval in Non-Patent Document 4 described above, the better. This is because, when the number of P-SCH sequences and the types of P-SCH transmission intervals are small, the probability that the P-SCH sequences are the same in adjacent cells, or the P-SCH transmission intervals are the same. This is because the probability of S-SCH characteristic deterioration in the inter-station synchronization system increases.

  In addition, the time required for the cell search, that is, the cell search transmission characteristics and the processing load of the mobile station when performing the cell search are in a trade-off relationship, and the cell setting depends on the parameter setting or operation method. It is desirable to be able to select whether the transmission characteristics of search are important or whether the processing load of the mobile station is important when performing cell search.

3GPP TR 25.814 (V7.0.0), “Physical Layer Aspects for Evolved UTRA,” June 2006 R1-062990, Outcome of cell search drafting session R1-062636, Cell Search Performance in Tightly Synchronized Network for E-UTRA R1-070428, Further analysis of initial cell search for Approach 1 and 2-single cell scenario 3GPP TS 36.211 V1.0.0 (2007-03) 3GPP R1-060042 SCH Structure and Cell Search Method in E-UTRA Downlink 3GPP R1-071584 Secondary Synchronization Signal Design C. Chu, “Polyphase codes with good periodic correlation properties,” IEEE Trans. Inform. Theory, vol. II-18, pp.531-532, July 1972 R.L.Frank and S.A.Zadoff, “Phase shift pulse codes with good periodic correlation properties,” IRE Trans. Inform. Theory, vol. IT-8, pp. 381-382, 1962 M.J.E.Golay, “Complementary Series,” IRE Trans. Inform. Theory, vol. 7, pp. 82-87, April 1961. R1-062487 Hierarchical SCH signals suitable for both (FDD and TDD) modes of E-UTRA 3GPP, R1-070146, S-SCH Sequence Design 3GPP, R1-072093, Details on SSC Sequence Design 3GPP, R1-071641, Frequency Hopping / Shifting of Downlink Reference Signal in E-UTRA 3GPP, R1-071794, Way forward for stage 2.5 details of SCH 3GPP, R1-072368, Mapping of Short Sequences for S-SCH

  However, the background art described above has the following problems.

  As described above, the synchronization channel (SCH) is downlink signaling used for cell search. Hierarchical SCH is determined to be applied to this synchronization channel (see Non-Patent Document 5, for example). That is, it is composed of two subchannels, a primary synchronization channel (Primary SCH) and a secondary synchronization channel (Secondary SCH).

  Among the primary synchronization channel and the secondary synchronization channel, in the secondary synchronization channel, cell-specific information such as a cell ID group, radio frame timing, and transmission antenna number information is notified. The user apparatus detects cell-specific information by detecting a secondary synchronization channel sequence.

  As described above, in the W-CDMA (Wideband Code Division Multiple Access) system, a neighbor cell search is performed when handover is performed. Prior to this neighbor cell search, cell-specific information (neighbor cell information) of neighbor cells Is notified to the user device in advance. However, in the LTE system, whether or not such neighboring cell information is notified has not been determined so far. In a neighboring cell search for detecting a cell that is a handover destination during communication or standby, if neighboring cell information or the like is notified in advance, the number of candidate cell-specific information to be detected can be reduced. .

As a secondary synchronization channel sequence mapping method, a method of mapping different sequences in the frequency direction has been proposed (see, for example, Non-Patent Document 6 and Non-Patent Document 7). For example, as shown in FIG. 1, an orthogonal sequence 1 (P ₁ (0), P ₁ (1),..., P ₁ (31)) and an orthogonal sequence 2 (P ₂ (0), P ₂ (1) ),..., P ₂ (31)) are alternately mapped every other subcarrier. Also, for example, as shown in FIG. 2, orthogonal sequence 1 (P ₁ (0), P ₁ (1),..., P ₁ (31)) and orthogonal sequence 2 (P ₂ (0), P ₂ (1),..., P ₂ (31)) are mapped to consecutive subcarriers. By dividing the sequence into a plurality of groups in this way, the number of patterns that can be transmitted can be increased. Specifically, for example, when one type of sequence having a sequence length of 64 is used, 64 types of patterns can be transmitted, whereas as shown in FIG. 2, two types of sequences having a sequence length of 32 are used. 1024 types of patterns can be transmitted.

  In view of the above-described problems, the present invention provides a base station apparatus, mobile station apparatus, and synchronization channel transmission method that can reduce the number of cell-specific information candidates to be detected in a neighboring cell search. There is to do.

A base station apparatus according to an embodiment
A base station apparatus used in a mobile communication system,
A generation unit for generating a synchronization channel used in a cell search of the user equipment;
A transmitter that wirelessly transmits a signal including the synchronization channel;
The synchronization channel has a primary synchronization channel for detecting reception timing, and a secondary synchronization channel including cell ID group information,
The secondary synchronization channel is composed of a plurality of different short codes,
A correspondence relationship between a combination of a plurality of short codes and cell ID group information is defined in advance,
The secondary synchronization channel is composed of a first short code designated by a first index number and a second short code designated by a second index number;
The base station apparatus is characterized in that second index number−first index number ≦ Δ (Δ is a positive integer).

  According to the embodiment of the present invention, it is possible to realize a base station apparatus, a mobile station apparatus, and a synchronization channel transmission method that can reduce the number of candidates for cell specific information to be detected in a neighboring cell search.

It is explanatory drawing which shows the mapping method of a S-SCH series. It is explanatory drawing which shows the mapping method of a S-SCH series. It is a block diagram which shows the structure of the radio | wireless communications system based on one Example of this invention. It is explanatory drawing which shows a radio | wireless frame structure. It is explanatory drawing which shows the structure of a sub-frame. It is a partial block diagram which shows the base station apparatus which concerns on one Example of this invention. It is a block diagram which shows the baseband signal processing part of the base station apparatus which concerns on one Example of this invention. It is explanatory drawing which shows an example of a synchronous signal transmission pattern. It is explanatory drawing which shows an example of a synchronous signal transmission pattern. It is explanatory drawing which shows an example of the combination of a P-SCH sequence number and a synchronous signal transmission pattern. It is explanatory drawing which shows an example of the combination of a P-SCH sequence number and a synchronous signal transmission pattern. It is explanatory drawing which shows an example of the combination of a P-SCH sequence number and a synchronous signal transmission pattern. It is explanatory drawing which shows an example of the combination of a P-SCH sequence number and a synchronous signal transmission pattern. It is explanatory drawing which shows an example of a synchronous signal transmission pattern. It is explanatory drawing which shows an example of the combination of a P-SCH sequence number and a synchronous signal transmission pattern. It is explanatory drawing which shows an example of a synchronous signal transmission pattern. It is explanatory drawing which shows an example of the combination of a P-SCH sequence number and a synchronous signal transmission pattern. It is explanatory drawing which shows an example of a synchronous signal transmission pattern. It is explanatory drawing which shows an example of the combination of a P-SCH sequence number and a synchronous signal transmission pattern. It is explanatory drawing which shows the mapping method of the S-SCH series which concerns on one Example of this invention. It is a partial block diagram which shows the mobile station apparatus which concerns on one Example of this invention. It is a flowchart which shows the cell search method based on one Example of this invention. It is explanatory drawing which shows an example of the mapping method of a short code. It is explanatory drawing which shows an example of the short code mapping method based on one Example of this invention. It is explanatory drawing which shows the mapping method of the S-SCH series which concerns on one Example of this invention. It is a figure for demonstrating the determination method of a S-SCH series. It is a figure for demonstrating another determination method of a S-SCH series. It is a figure for demonstrating another determination method of a S-SCH series. It is a figure which shows an example of the mapping method of a short code. It is a figure which shows the correspondence of a short code and a scramble code.

  Embodiments of the present invention will be described below with reference to the drawings. In all the drawings for explaining the embodiments, the same reference numerals are used for those having the same function, and repeated explanation is omitted.

  A radio communication system having a mobile station and a base station apparatus according to an embodiment of the present invention will be described with reference to FIG.

The wireless communication system 1000 is a system to which, for example, Evolved UTRA and UTRAN (also known as Long Term Evolution, or Super 3G) is applied. The wireless communication system 1000 includes a base station device (eNB: eNode B) 200 _m (200 ₁ , 200 ₂ , 200 ₃ ,..., 200 _m , m is an integer of m> 0), a base station device 200 _m A plurality of mobile stations 100 _n (100 ₁ , 100 ₂ , 100 ₃ ,... 100 _n , where n is an integer of n> 0). Base station apparatus 200 is connected to an upper station, for example, access gateway apparatus 300, and access gateway apparatus 300 is connected to core network 400. The mobile station 100 _n communicates with the base station apparatus 200 _{m using} Evolved UTRA and UTRAN in any of the cells 50 _k (50 ₁ , 50 ₂ ,..., 50 _k , k is an integer of k> 0).

Here, the mobile station 100 _n establishes a communication channel with any one of the base station devices 200 _m and establishes a communication channel with any one of the base stations 200 _m and the base station 200 _m , so that there is no communication. It is assumed that things in a state are mixed.

The base station device 200 _m transmits a synchronization signal. The mobile station 100 _n is located in one of the cells 50 _k (50 ₁ , 50 ₂ , 50 ₃ ,... 50 _k , k is an integer of k> 0), and is powered on or in communication At the time of intermittent reception or the like, a cell search for detecting a cell having good radio quality for the own station is performed based on the synchronization signal. In other words, the mobile station 100 _n detects the symbol timing and the frame timing using the synchronization signal, and uses a cell ID (cell-specific scramble code generated from the cell ID) or a set of cell IDs (hereinafter cell ID). Cell-specific control information such as a group) is detected.

Here, the cell search is performed both when the mobile station 100 _n is in a communication state and when it is in a no-communication state. For example, the cell search in the communication state includes a cell search for detecting a cell having the same frequency and a cell search for detecting a cell having a different frequency. In addition, cell search in the wireless communication state includes, for example, cell search at power-on and cell search at standby.

Hereinafter, since the base station apparatus 200 _m (200 ₁ , 200 ₂ , 200 ₃ ,... 200 _m ) has the same configuration, function, and state, the base station apparatus 200 _m is hereinafter referred to as the base station 200 _m unless otherwise specified. Proceed with the explanation. Hereinafter, since the mobile station 100 _n (100 ₁ , 100 ₂ , 100 ₃ ,... 100 _n ) has the same configuration, function, and state, the following description will be given as the mobile station 100 _n unless otherwise specified. To proceed. Hereinafter, since the cells 50 _k (50 ₁ , 50 ₂ , 50 ₃ ,... 50 _k ) have the same configuration, function, and state, the following description will be given as the cell 50 _k unless otherwise specified. .

  Radio communication system 1000 employs OFDM (Orthogonal Frequency Division Multiple Access) for the downlink and SC-FDMA (Single Carrier Frequency Division Multiple Access) for the uplink as the radio access scheme. As described above, OFDM is a scheme in which a frequency band is divided into a plurality of narrow frequency bands (subcarriers) and data is transmitted on each frequency band. SC-FDMA is a transmission method that can reduce interference between terminals by dividing a frequency band and performing transmission using different frequency bands among a plurality of terminals.

  Here, communication channels in Evolved UTRA and UTRAN will be described.

For the downlink, a downlink shared physical channel (PDSCH) shared by each mobile station 100 _n and a downlink control channel for LTE are used. In the downlink, the mobile station information and transport format information mapped to the downlink shared physical channel, the mobile station information and transport format information mapped to the uplink shared physical channel, by the downlink control channel for LTE, The acknowledgment information of the uplink shared physical channel is notified, and user data is transmitted through the downlink shared physical channel.

In the downlink, the base station apparatus 200 _m transmits a synchronization signal for the mobile station 100 _n to perform cell search.

For the uplink, an uplink shared physical channel (PUSCH) shared by each mobile station 100 _n and an uplink control channel for LTE are used. There are two types of uplink control channels: channels that are time-multiplexed with uplink shared physical channels and channels that are frequency-multiplexed.

  In the uplink, downlink quality information (CQI: Channel Quality Indicator) to be used for scheduling of the shared physical channel in the downlink, adaptive modulation and coding (AMC: Adaptive Modulation and Coding) by the uplink control channel for LTE. And acknowledgment information (HARQ ACK information) of the downlink shared physical channel is transmitted. Also, user data is transmitted through the uplink shared physical channel.

  In downlink transmission, as shown in FIG. 4, one radio frame (Radio Frame) is 10 ms, and there are 10 subframes in one Radio Frame. In addition, as shown in FIG. 5, one subframe is composed of two slots, and one slot includes seven OFDM symbols and a long CP (Long CP) when a short CP (Short CP) is used. Is used, it is composed of 6 OFDM symbols.

Next, base station apparatus 200 _{m according} to an embodiment of the present invention will be described with reference to FIG.

  The base station apparatus 200 according to the present embodiment includes a transmission / reception antenna 202, an amplifier unit 204, a transmission / reception unit 206, a baseband signal processing unit 208, a call processing unit 210, and a transmission path interface 212.

Packet data transmitted from the base station apparatus 200 _m to the mobile station 100 _n via the downlink is subjected to baseband signal processing from the upper station located above the base station apparatus 200, for example, the access gateway apparatus 300 via the transmission path interface 212. Input to the unit 208.

  The baseband signal processing unit 208 divides and combines packet data, RLC layer transmission processing such as RLC (radio link control) retransmission control transmission processing, MAC retransmission control, for example, HARQ (Hybrid Automatic Repeat Request) transmission processing, Scheduling, transmission format selection, channel coding, inverse fast Fourier transform (IFFT) processing is performed, and the data is transferred to the transmission / reception unit 206. The baseband signal processing unit 208 performs a synchronization signal generation process as will be described later. The synchronization signal is multiplexed with the packet data and transferred to the transmission / reception unit 206.

  The transmission / reception unit 206 performs frequency conversion processing for converting the baseband signal output from the baseband signal processing unit 208 into a radio frequency band, and then is amplified by the amplifier unit 204 and transmitted from the transmission / reception antenna 202. Here, the baseband signal is the above-described packet data, synchronization signal, or the like.

On the other hand, for data transmitted from the mobile station 100 _n to the base station apparatus 200 _m via the uplink, a radio frequency signal received by the transmission / reception antenna 202 is amplified by the amplifier unit 204, and frequency-converted by the transmission / reception unit 206. It is converted into a band signal and input to the baseband signal processing unit 208.

  The baseband signal processing unit 208 performs FFT processing, error correction decoding, MAC retransmission control reception processing, and RLC layer reception processing on the input baseband signal, and the access gateway device via the transmission path interface 212 300.

  The call processing unit 210 performs state management of the radio base station 200 and resource allocation.

  Next, the configuration of the baseband signal processing unit 208 will be described with reference to FIG. In addition, since the embodiment according to the present invention mainly relates to the downlink, in the same figure, the portion related to the downlink processing is shown, and the portion related to the uplink processing is omitted.

The baseband signal processing unit 208 includes a RLC processing unit _{208 1, MAC (Medium Access Control} ) processing unit 208 _2, an encoding unit 208 _3, a data modulation unit 208 _4, a multiplexing unit 208 _5, deserializer and parts 208 _6, a multiplier 208 _7, a multiplier 208 _8, a scramble code generator 208 _9, an amplitude adjusting unit _{208 10,} a combining unit _{208 11,} and IFFT (IDFT) _{208 12,} CP adding section 208 ₁₃ and a synchronization signal generation unit 209.

Transmission data sequence of downlink packet data received from the transmission path interface unit, in the RLC processing unit 208 _1, segmentation and concatenation, transmission processing of RLC layer transmission processing such as the RLC retransmission control is performed, MAC processor 208 in _2, the transmission processing of HARQ (Hybrid Automatic Repeat reQuest), scheduling, selection of transmission format, after the transmission processing of the MAC layer assignment such frequency resources is performed, encoded in the encoding unit 208 _3, a data is data modulated in modulation section 208 _4. Then, the transmission data sequence which is data-modulated, pilot symbol in multiplexing section 208 ₅ are multiplexed, the transmission data sequence in which the pilot symbols are multiplexed, on the frequency axis is parallel conversion in the serial-parallel conversion unit 208 ₆ It is converted into N information symbol sequences and arranged on the frequency axis. Here, the pilot symbol is, for example, a Donlink reference signal. For N information symbol sequences aligned on the frequency axis, in each of N multipliers 208 _7, the scrambling code scrambling code generating unit 208 ₉ outputs is multiplied in the frequency direction, further, the scrambling code Is multiplied by the amplitude adjustment sequence value output from the amplitude adjustment unit 208 _{10 in} each of the N multiplication units 208 ₈ , and is output to the synthesis unit 208 ₁₁ . Combining unit 208 _11, the symbol sequence of the scrambling code and amplitude adjusting sequence value-multiplied sequence length N, the sync signal generated in the synchronization signal generating unit 209, specific to corresponding one of the N subcarriers Multiplex on subcarriers.

As described later, subframes and slots synchronization signal is transmitted is determined by the synchronization signal control unit 209 _1. In the subframe number and slot number in which the synchronization signal is transmitted, the synchronization signal generated by the synchronization signal generation unit 209 is the sequence length N downlink packet data multiplied by the scramble code and the amplitude adjustment sequence value. In the subframe number and the slot number that are multiplexed with respect to the symbol sequence and the synchronization signal is not transmitted, the synchronization signal generated in the synchronization signal generation unit 209 is not multiplexed, and is multiplied by the scramble code and the amplitude adjustment sequence value. only the symbol sequence of downlink packet data of the sequence length N is transmitted to the inverse Fourier transform unit 208 _12. The subcarrier on which the synchronization signal is multiplexed is located at the center of the entire bandwidth, for example. The bandwidth of the subcarrier on which the synchronization signal is multiplexed is 1.25 MHz.

The inverse Fourier transform unit (IFFT unit) 208 ₁₂ converts the N symbols into orthogonal multicarrier signals. CP adding section _{208 13,} to the multi-carrier signal for each Fourier target time, it inserts a CP. There are two types of CP length (CP length), Long CP and Short CP, and which CP length is used for each cell is selected.

A synchronization signal generation process in the synchronization signal generation unit 209 will be described. The synchronization signal is composed of a first synchronization signal (hereinafter referred to as P-SCH) and a second synchronization signal (hereinafter referred to as S-SCH). The synchronization signal generation unit 209 includes a synchronization signal control unit 209 ₁ , a synchronization signal generation unit 209 ₂ , a data modulation unit 209 ₃ , a serial / parallel conversion unit 209 ₄ , a multiplier 209 _5, and an amplitude adjustment unit 209 ₆ It comprises. The synchronization signal control unit 209 ₁ is connected to the synchronization signal generation unit 209 ₂ .

The synchronization signal control unit 209 ₁ determines the P-SCH sequence number, the P-SCH, and the S based on the cell ID or cell ID group of the cell for which the base station apparatus 200 _m provides communication using Evolved UTRA and UTRAN. -Determine the subframe number and slot number in which the SCH is transmitted. For example, after specifying the cell ID group, the mobile station may specify the cell based on the pilot signal, that is, the signal pattern of the Reference Signal. In this case, for example, the reference signal signal pattern and the cell ID are defined in advance. Or a mobile station may specify a cell based on the demodulation and decoding of P-SCH and S-SCH, for example. In this case, for example, the P-SCH sequence number and the cell ID information are defined in advance.

The synchronization signal control unit 209 _1, the sequence number of the P-SCH, and notifies the sync signal generator 209 ₂ as the synchronization signal sequence information. Further, the subframe number and the slot number the P-SCH and S-SCH are transmitted, and notifies the sync signal generator 209 ₂ as synchronization signal transmission timing information.

For example, as shown in Non-Patent Document 5 and FIG. 8, the wireless communication system 1000 defines a subframe number and a slot number in which P-SCH and S-SCH are transmitted. In this example, a plurality of types of P-SCH sequences are used, and a synchronization signal is transmitted in subframe number # 1 and subframe number # 6. Further, in this example, P-SCH is mapped to the last OFDM symbol of the slot slot, so that the mobile station uses P- regardless of whether Long CP or Short CP is used. SCH demodulation can be performed. The reason is that, in the last OFDM symbol of the slot, the sixth OFDM symbol when the Long CP is applied and the seventh OFDM symbol when the Short CP is applied coincide in time. In other words, the timing at the beginning and end of the subframe is the same for both the short CP and the long CP. At this time, the wireless communication system may associate the P-SCH sequence number and the cell ID information in advance. By such an association is performed by the wireless communication system 1000, the synchronization signal control unit 209 ₁ of the base stations 200 _m of the cell in which the base stations 200 _m provides communications using the Evolved UTRA and UTRAN The P-SCH sequence number can be determined based on the cell ID.

  Alternatively, for example, as shown in FIG. 9, the wireless communication system 1000 defines four types of subframe numbers and slot numbers in which P-SCH and S-SCH are transmitted, and a synchronization signal transmission pattern # 1 respectively. , # 2, # 3, and # 4. In this example, since the synchronization signal is transmitted in subframe number # 1 and subframe number # 6, the synchronization signal is transmitted at equal intervals, and the mobile station can easily perform the averaging process of a plurality of frames. Become. Further, in this example, P-SCH is mapped to the last OFDM symbol of the subframe, so that the mobile station can use P- regardless of whether Long CP or Short CP is used. SCH demodulation can be performed.

Then, for example, as illustrated in FIG. 10, the wireless communication system 1000 uses eight P-SCH sequences and two synchronization signal transmission patterns to generate eight P-SCH sequences and synchronization signal transmission patterns. Combinations may be defined. At this time, the wireless communication system is configured such that the cell ID or the cell ID group, the P-SCH sequence, and the synchronization signal transmission pattern are set so that the combination of the adjacent cell, the P-SCH sequence, and the synchronization signal transmission pattern is not the same. A combination may be associated. By such an association is performed by the wireless communication system 1000, the synchronization signal control unit 209 ₁ of the base stations 200 _m of the cell in which the base stations 200 _m provides communications using the Evolved UTRA and UTRAN Based on the cell ID or the cell ID group, the P-SCH sequence number and the subframe number and slot number in which the P-SCH and S-SCH are transmitted can be determined. At this time, as one of information elements mapped to S-SCH, whether the synchronization signal, that is, P-SCH and S-SCH is transmitted in synchronization signal transmission patterns # 1 and # 4. May be included. At this time, the mobile station can determine, for example, whether the transmission is performed in the synchronization signal transmission pattern # 1 or # 4 based on the information element included in the S-SCH.

  When the combinations shown in FIG. 10 are defined, when the combination numbers are different, it is possible to prevent the P-SCH from colliding in time or the characteristics of the S-SCH from deteriorating due to different sequences. It becomes possible.

Alternatively, as shown in FIG. 11, the wireless communication system 1000 uses the four P-SCH sequences and the two synchronization signal transmission patterns to combine the eight P-SCH sequences and the synchronization signal transmission patterns. It may be defined. At this time, the wireless communication system is configured such that the cell ID or the cell ID group, the P-SCH sequence, and the synchronization signal transmission pattern are set so that the combination of the adjacent cell, the P-SCH sequence, and the synchronization signal transmission pattern is not the same. A combination may be associated. By such an association is performed by the wireless communication system 1000, the synchronization signal control unit 209 ₁ of the base stations 200 _m of the cell in which the base stations 200 _m provides communications using the Evolved UTRA and UTRAN Based on the cell ID or the cell ID group, the P-SCH sequence number and the subframe number and slot number in which the P-SCH and S-SCH are transmitted can be determined. At this time, as one of the information elements mapped to S-SCH, whether the synchronization signal, that is, P-SCH and S-SCH is transmitted in synchronization signal transmission pattern # 2 or # 3. The information may not be included. For example, the mobile station can determine whether the transmission is performed using the synchronization signal transmission pattern # 2 or # 3 based on the time interval of the received P-SCH. When the combinations shown in FIG. 11 are defined, when the combination numbers are different, it is possible to prevent the P-SCH from colliding in time or the characteristics of the S-SCH from being deteriorated due to different sequences. It becomes possible.

Alternatively, as shown in FIG. 12, the wireless communication system 1000 uses the three P-SCH sequences and the three synchronization signal transmission patterns to combine the nine P-SCH sequences and the synchronization signal transmission patterns. May be defined. At this time, in the wireless communication system, the cell ID or the cell ID group, the P-SCH sequence, and the synchronization signal transmission pattern are set so that the combination of the adjacent cell, the P-SCH sequence, and the synchronization signal transmission pattern is not the same. You may associate with the combination of. By such an association is performed by the wireless communication system 1000, the synchronization signal control unit 209 ₁ of the base stations 200 _m of the cell in which the base stations 200 _m provides communications using the Evolved UTRA and UTRAN Based on the cell ID or the cell ID group, the P-SCH sequence number and the subframe number and slot number in which the P-SCH and S-SCH are transmitted can be determined. At this time, as one of the information elements mapped to the S-SCH, the synchronization signal, that is, the P-SCH and the S-SCH are transmitted in any of the synchronization signal transmission patterns # 1, # 2, and # 3. It does not have to include information on whether or not For example, the mobile station can determine which of the synchronization signal transmission patterns # 1, # 2, and # 3 is transmitted based on the received P-SCH time interval. When the combinations shown in FIG. 12 are defined, even when the combination numbers are different, there are cases where the P-SCHs collide in time, but there are cases where the P-SCHs do not collide in time. It is possible to prevent a little deterioration of the characteristics of the SCH. On the other hand, since only three P-SCH sequences are used to define a combination of nine P-SCH sequences and synchronization signal transmission patterns, the processing load on the mobile station can be reduced. Furthermore, by defining the combinations shown in FIG. 12, it is possible to select the combinations more flexibly when associating the cell ID or the cell ID group with the combinations shown in FIG. For example, only the combinations # 2, # 3, # 5, # 6, # 8, and # 9 can be used in a cell in an area where it is desired to prevent the degradation of S-SCH characteristics as much as possible. In this case, the P-SCH sequence and the synchronization signal transmission pattern used are equivalent to those in FIG. 11, and since the P-SCH does not collide with time, it is possible to prevent degradation of the S-SCH characteristics as much as possible. Become. On the other hand, all of the combinations # 1 to # 9 can be used in a cell in an area where the S-SCH characteristics may be somewhat degraded. In this case, it becomes easy to associate the cell ID or the cell ID group with the combination.

  In FIG. 12, the synchronization signal patterns are # 1, # 2, and # 3, but may be # 2, # 3, and # 4 instead.

Alternatively, as illustrated in FIG. 13, the wireless communication system 1000 uses the two P-SCH sequences and the four synchronization signal transmission patterns to combine the eight P-SCH sequences and the synchronization signal transmission patterns. May be defined. At this time, the wireless communication system is configured such that the cell ID or the cell ID group, the P-SCH sequence, and the synchronization signal transmission pattern are set so that the combination of the adjacent cell, the P-SCH sequence, and the synchronization signal transmission pattern is not the same. A combination may be associated. By such an association is performed by the wireless communication system 1000, the synchronization signal control unit 209 ₁ of the base stations 200 _m of the cell in which the base stations 200 _m provides communications using the Evolved UTRA and UTRAN Based on the cell ID or the cell ID group, the P-SCH sequence number and the subframe number and slot number in which the P-SCH and S-SCH are transmitted can be determined. At this time, as one of information elements mapped to the S-SCH, the synchronization signal, that is, the P-SCH and the S-SCH are the synchronization signal transmission patterns # 1, # 2, # 3, and # 4. Information on which is being transmitted may be included. At this time, for example, the mobile station can determine which of the synchronization signal transmission patterns # 1, # 2, # 3, and # 4 is being transmitted based on the information element included in the S-SCH. When the combinations shown in FIG. 13 are defined, even when the combination numbers are different, there are cases where the P-SCHs collide in time, but there are cases where the P-SCHs do not collide in time. It is possible to prevent a little deterioration of the characteristics of the SCH. On the other hand, since only two P-SCH sequences are used to define a combination of eight P-SCH sequences and synchronization signal transmission patterns, the processing load on the mobile station can be reduced.

  Furthermore, by defining the combinations shown in FIG. 13, it is possible to select the combinations more flexibly when associating the cell IDs or cell ID groups with the combinations shown in FIG. For example, only the combinations # 1, # 4, # 5, and # 8 can be used in a cell in an area where it is desired to prevent the degradation of S-SCH characteristics as much as possible. In this case, the P-SCH sequence to be used and the synchronization signal transmission pattern are equivalent to those in FIG. 10, and since the P-SCH does not collide with time, it is possible to prevent the degradation of the S-SCH characteristics as much as possible. Become. On the other hand, all the combinations # 1 to # 8 can be used in a cell in an area where the S-SCH characteristics may be somewhat degraded. In this case, the cell ID or the cell ID group can be easily associated with the above combination.

  In FIG. 9 described above, P-SCH and S-SCH are transmitted in subframe number # 1 and subframe number # 6. Instead, subframe number # 1 and subframe number # 5 are transmitted. May be transmitted. That is, by transmitting the synchronization signal at different intervals, it becomes possible for the mobile station to easily detect the boundary of the radio frame from the P-SCH transmission interval. In this case, P-SCH and S-SCH are transmitted in subframe number # 1 and subframe number # 5, as in the case where P-SCH and S-SCH are transmitted in subframe number # 1 and subframe number # 6. For SCH and S-SCH, synchronization signal transmission patterns # 1, # 2, # 3, and # 4 shown in FIG. 9 are defined, and P-SCH sequence numbers and synchronization signals shown in FIGS. A combination of transmission patterns is defined, and a cell ID or a cell ID group is associated with a combination of a P-SCH sequence number and a synchronization signal transmission pattern.

  Further, for example, as shown in FIG. 14, the wireless communication system 1000 defines two types of subframe numbers and slot numbers in which P-SCH and S-SCH are transmitted, and synchronization signal transmission pattern # 1, It is defined as # 2. In this example, since the synchronization signal is transmitted in subframe number # 1 and subframe number # 5, the synchronization signal is transmitted at different intervals, and the boundary of the radio frame is easily detected in the mobile station. It becomes possible. Also, in this example, the P-SCH is mapped to the last OFDM symbol of the slot, so that the mobile station uses the P-SCH regardless of whether the Long CP or the Short CP is used. Can be demodulated. The reason is that, in the last OFDM symbol of the slot, the sixth OFDM symbol when the Long CP is applied and the seventh OFDM symbol when the Short CP is applied coincide in time. A feature of this synchronization signal transmission pattern is that S-SCH is transmitted only to subframe number # 1 in one Radio Frame, and S-SCH is not transmitted in the case of subframe number # 5. Since the P-SCH transmission interval is not uniform, the mobile station can easily detect the boundary of the radio frame, and the mobile station demodulates the S-SCH only in subframe number # 1. . In subframe number # 1, since the OFDM symbols to which P-SCH and S-SCH are transmitted differ between synchronization signal transmission patterns # 1 and # 2, P-SCH may collide in time. Therefore, it is possible to prevent the characteristics of the S-SCH from deteriorating.

Then, as shown in FIG. 15, the wireless communication system 1000 uses the four P-SCH sequences and the two synchronization signal transmission patterns to combine the eight P-SCH sequences and the synchronization signal transmission patterns. May be defined. At this time, the wireless communication system is configured such that the cell ID or the cell ID group, the P-SCH sequence, and the synchronization signal transmission pattern are set so that the combination of the adjacent cell, the P-SCH sequence, and the synchronization signal transmission pattern is not the same. A combination may be associated. By such an association is performed by the wireless communication system 1000, the synchronization signal control unit 209 ₁ of the base stations 200 _m of the cell in which the base stations 200 _m provides communications using the Evolved UTRA and UTRAN Based on the cell ID or the cell ID group, the P-SCH sequence number and the subframe number and slot number in which the P-SCH and S-SCH are transmitted can be determined. At this time, as one of information elements mapped to S-SCH, whether the synchronization signal, that is, P-SCH and S-SCH is transmitted in synchronization signal transmission pattern # 1 or # 2 The information may not be included. At this time, for example, the mobile station can determine whether the transmission is performed in synchronization signal transmission pattern # 1 or # 2 based on the received P-SCH time interval.

  Further, for example, as shown in FIG. 16, the wireless communication system 1000 defines three types of subframe numbers and slot numbers in which P-SCH and S-SCH are transmitted, and synchronization signal transmission pattern # 1, It is defined as # 2 and # 3. In this example, since the synchronization signal is transmitted in subframe number # 1 and subframe number # 6, the synchronization signal is transmitted at equal intervals, and the mobile station can easily perform the averaging process of a plurality of frames. Become. This synchronization signal pattern has a feature that the transmission timing of the P-SCH does not match when the synchronization signal transmission patterns are different.

Then, as shown in FIG. 17, the wireless communication system 1000 uses the three P-SCH sequences and the three synchronization signal transmission patterns to combine the nine P-SCH sequences and the synchronization signal transmission patterns. It may be defined. At this time, the wireless communication system is configured such that the cell ID or the cell ID group, the P-SCH sequence, and the synchronization signal transmission pattern are set so that the combination of the adjacent cell, the P-SCH sequence, and the synchronization signal transmission pattern is not the same. A combination may be associated. By such an association is performed by the wireless communication system 1000, the synchronization signal control unit 209 ₁ of the base stations 200 _m cell ID to which the base stations 200 _m provides communications using the Evolved UTRA and UTRAN Alternatively, based on the cell ID group, it is possible to determine the P-SCH sequence number and the subframe number and slot number in which the P-SCH and S-SCH are transmitted. At this time, as one of information elements mapped to the S-SCH, the synchronization signal, that is, the P-SCH and the S-SCH are transmitted in any of the synchronization signal transmission patterns # 1, # 2, and # 3. May be included. At this time, for example, the mobile station can determine which of the synchronization signal transmission patterns # 1, # 2, and # 3 is transmitted based on the information element included in the S-SCH.

  When the combinations shown in FIG. 17 are defined, when the combination numbers are different, it is possible to prevent the P-SCH from colliding with time or the characteristics of the S-SCH from deteriorating due to different sequences. It becomes possible.

  Further, for example, as shown in FIG. 18, the wireless communication system 1000 defines four types of subframe numbers and slot numbers in which P-SCH and S-SCH are transmitted, and synchronization signal transmission pattern # 1, It is defined as # 2, # 3, # 4. In this example, since the synchronization signal is transmitted in subframe number # 1 and subframe number # 6, the synchronization signal is transmitted at equal intervals, and the mobile station can easily perform the averaging process of a plurality of frames. Become. This synchronization signal pattern has a feature that the transmission timing of the P-SCH does not match when the synchronization signal transmission patterns are different. Also, the difference from the synchronization signal transmission pattern shown in FIG. 16 is that, in the synchronization signal transmission pattern shown in FIG. 16, the OFDM symbols to which P-SCH and S-SCH are mapped are contained within one slot. In the synchronization signal transmission pattern shown in FIG. 13, the OFDM symbols to which P-SCH and S-SCH are mapped are not in one slot but in two slots, that is, in one subframe.

Then, as illustrated in FIG. 19, the wireless communication system 1000 uses two P-SCH sequences and four synchronization signal transmission patterns to combine eight P-SCH sequences and synchronization signal transmission patterns. May be defined. At this time, the wireless communication system is configured such that the cell ID or the cell ID group, the P-SCH sequence, and the synchronization signal transmission pattern are set so that the combination of the adjacent cell, the P-SCH sequence, and the synchronization signal transmission pattern is not the same. A combination may be associated. By such an association is performed by the wireless communication system 1000, the synchronization signal control unit 209 ₁ of the base stations 200 _m of the cell in which the base stations 200 _m provides communications using the Evolved UTRA and UTRAN Based on the cell ID or the cell ID group, the P-SCH sequence number and the subframe number and slot number in which the P-SCH and S-SCH are transmitted can be determined. At this time, as one of information elements mapped to the S-SCH, the synchronization signal, that is, the P-SCH and the S-SCH are the synchronization signal transmission patterns # 1, # 2, # 3, and # 4. It does not have to include information on which is being transmitted. At this time, for example, the mobile station can determine which of the synchronization signal transmission patterns # 1, # 2, # 3, and # 4 is transmitted based on the received P-SCH time interval.

  When the combinations shown in FIG. 19 are defined, when the combination numbers are different, it is possible to prevent the P-SCH from colliding in time or the characteristics of the S-SCH from deteriorating due to different sequences. It becomes possible.

In general, the communication area provided by the base station apparatus 200 _m is divided into two or more areas. This is called sectorization. When the base station apparatus 200 _m has a plurality of sectors, the cell ID or the cell ID group may be used as an ID of an area combining all the sectors of the base station apparatus 200 _{m. It} may be used as the ID of each sector of _m . When a cell ID or a cell ID group is used as an ID of an area including all sectors of the base station apparatus 200 _m , the synchronization signal sequence, a subframe number and a slot number in which the synchronization signal is transmitted, Is set for each base station apparatus 200 _m . When the cell ID or the cell ID group is used as the ID of each sector of the base station apparatus 200 _m , the combination of the synchronization signal sequence and the subframe number and slot number to which the synchronization signal is transmitted is It is set for each sector of the station apparatus 200 _m .

Examples of P-SCH sequences include CAZAC (Constant Amplitude Zero Auto Correlation sequence) sequences such as Zadoff-Chu sequences (Non-patent document 8), Frank sequences (Non-patent document 9), Modulated Frank sequences (Non-patent document 9), and Golay sequences. (Non-Patent Document 10), Double
A Repetitive Golay Complementary sequence (Non-Patent Document 11), a PN (Pseudo Noise) sequence, or the like may be used.

  Further, as the S-SCH sequence, a non-orthogonal sequence or a scramble sequence that is an orthogonal sequence may be a two-layer S-SCH sequence (Non-patent Document 12) obtained by multiplying an orthogonal sequence or a non-orthogonal sequence. An S-SCH sequence in which a plurality of orthogonal sequences or non-orthogonal sequences are alternately arranged in the frequency domain may be used, or a plurality of orthogonal sequences or non-orthogonal sequences may be multiplied by a scramble sequence that is a non-orthogonal sequence or an orthogonal sequence An S-SCH sequence (Non-Patent Document 6) may be used, or an S-SCH sequence (Non-Patent Document 7) in which a plurality of orthogonal sequences or non-orthogonal sequences are arranged in consecutive subcarriers may be used. An S-SCH sequence in which a plurality of orthogonal sequences or non-orthogonal sequences are arranged in consecutive subcarriers and multiplied by a scramble sequence that is a non-orthogonal sequence or an orthogonal sequence may be used. As the orthogonal sequence, a Walsh-Hadamard sequence, a phase rotation orthogonal sequence, and an orthogonal M sequence may be used. As the non-orthogonal sequence, a CAZAC sequence such as a GCL sequence, a Golay sequence, etc. , Golay Complementary sequence (Non-patent document 10), M-sequence (Non-patent document 13), PN sequence, and the like may be used.

Synchronization signal generator 209 _2, based on the synchronization signal sequence information and synchronization signal transmission timing information reported from the synchronization signal control unit 209 _1, generates a synchronization signal sequence. Here, the synchronization signal sequence is either P-SCH or S-SCH.

For example, the synchronization signal generator 209 _2, when generating the S-SCH, may be a hierarchy of cell-specific information reported in S-SCH. The cell-specific information includes at least one information among cell ID group, radio frame timing, and transmission antenna number information. Here, when the mobile station performs a cell search, the wireless communication system 1000 may notify a part of the layered information as prior information such as neighboring cell information. For example, as a prior information, a cell ID group may be notified, a part of the cell ID group may be notified, a radio frame timing may be notified, or transmission antenna number information may be notified. Alternatively, any one piece of information may be included among information obtained by combining a part of the cell ID group, the cell ID group, the radio frame timing, and the transmission antenna number information. In this way, the number of sequences detected when the mobile station performs cell search can be reduced. Specifically, for example, as shown in FIG. 20, a cell ID group is represented by a combination of sequence indexes in a plurality of types of sequences, for example, two types of 32-chip length sequences (short codes). In FIG. 20, there are 29 types of first cell ID groups and 6 types of second layer cell ID groups, and the cell ID group is uniquely determined by the combination of the first cell ID group and the second layer cell ID group. (This makes it possible to distinguish 29 × 6 = 174 cell ID groups.) In sequence 2, radio frame timing and / or transmission antenna number information may be transmitted. For example, when the mobile station is notified of the cell ID group as prior information, the mobile station only needs to detect the radio frame timing and the number of transmission antennas during handover.

  In LTE, with respect to hopping / shifting of a downlink reference signal, it has been proposed to transmit a downlink reference signal by dividing it into 29 hopping patterns and 6 shift patterns (see, for example, Non-Patent Document 14). ). Information transmitted in two types of 29 and 6 types of sequences may be associated with the frequency hopping / shifting pattern of the downlink reference signal. By doing so, for example, when the frequency hopping pattern is notified by the prior information, the first layer cell ID group is notified, and the step of detecting the first layer cell ID group can be omitted. it can.

  The number of sequences to be detected can also be reduced when information such as information on the number of transmission antennas and radio frame timing is notified as neighboring cell information.

The synchronization signal sequence generated by the synchronization signal generation unit 209 ₂ is data-modulated by the data modulation unit 209 ₃ , and is further subjected to serial / parallel conversion by the serial / parallel conversion unit 209 ₄ to be converted into N _SCH symbol sequences on the frequency axis. Converted. The multiplier 209 ₅ multiplies the N _SCH symbol signals by the amplitude adjustment sequence value input by the amplitude adjustment unit 209 ₆ and outputs the result to the synthesis unit 208 ₁₁ .

  Next, the mobile station 100 according to the present embodiment is described with reference to FIG.

  The mobile station 100 includes a basic waveform correlation unit 102, a synchronization signal replica generation unit 104, a code sequence multiplication unit 106, an upper layer code correlation unit 108, a timing detection unit 110, and an S-SCH detection unit 112.

  The mobile station 100 inputs the multicarrier signal received by the antenna to the basic waveform correlation unit 102. On the other hand, the synchronization signal replica generation unit 104 generates a synchronization signal replica having a preset basic waveform, and sequentially inputs the synchronization signal replica to the basic waveform correlation unit 102. The basic waveform correlator 102 detects the correlation between the received multicarrier signal and the basic waveform synchronization signal replica. The code sequence multiplication unit 106 multiplies (or reverses the code) the output of the basic waveform correlation unit 102 for the basic waveform by the code sequence. Upper layer code correlation section 108 detects the correlation of the output of code sequence multiplication section 106 with the upper layer code. In this way, P-SCH replica correlation can be performed.

  Timing detection section 110 detects the P-SCH timing and the P-SCH sequence number from the correlation value. When the P-SCH timing is detected, the S-SCH detection unit 112 detects the S-SCH using the P-SCH as a reference signal. Here, for example, when the cell ID group is notified as the prior information, the radio frame timing and the transmission antenna number information are detected. If the base station is scrambled, it is necessary to perform descrambling after synchronous detection.

  This will be specifically described.

Cell search is performed by P-SCH and S-SCH included in downlink signals. Note that a cell search is performed based on the P-SCH sequence and the S-SCH sequence defined by the wireless communication system 1000 described above. That is, the cell ID or the cell ID group is detected by detecting the P-SCH sequence and the S-SCH sequence. Then, after detecting the cell ID, broadcast information is received using a scrambling code associated with the cell ID, and the cell search process is terminated. The details of the P-SCH sequence and the synchronization signal transmission pattern defined by the wireless communication system 1000 are the same as those described in the base station apparatus 200 _m , and will not be repeated.

  For example, when the wireless communication system 1000 defines the synchronization signal transmission pattern in FIG. 8 and the P-SCH sequence number and the cell ID information are associated in advance, the timing detection unit 110 sets the synchronization channel Timing and P-SCH sequence numbers are detected. In addition, the S-SCH detection unit 112 can detect cell-specific information by detecting an information element included in the S-SCH, for example.

  Alternatively, for example, the wireless communication system 1000 defines the synchronization signal transmission pattern in FIG. 9 and the combinations of the eight P-SCH sequences and the synchronization signal transmission pattern in FIG. 10 and is mapped to the S-SCH. When one of the information elements includes information indicating whether the synchronization signal, that is, P-SCH and S-SCH is transmitted in synchronization signal transmission pattern # 1 or # 4, S -SCH detection part 112 can determine whether it is transmitting by synchronous signal transmission pattern # 1 or # 4 based on the information element contained in S-SCH, for example. Then, the timing detection unit 110 can detect the cell ID or the cell ID group by detecting the P-SCH sequence and the synchronization signal transmission pattern.

  Alternatively, the wireless communication system 1000 defines the synchronization signal transmission pattern in FIG. 9 and the combinations of the eight P-SCH sequences and the synchronization signal transmission pattern in FIG. 11 and is mapped to the S-SCH. As one of the above, even when the synchronization signal, that is, the information indicating whether the P-SCH and S-SCH are transmitted in the synchronization signal transmission pattern # 2 or # 3 is not included, the basic waveform correlation unit For example, 102 can determine whether the transmission is performed in synchronization signal transmission patterns # 2 or # 3 based on the time interval of the received P-SCH. Then, the timing detection unit 110 can detect the cell ID or the cell ID group by detecting the P-SCH sequence and the synchronization signal transmission pattern.

  Alternatively, the wireless communication system 1000 defines the synchronization signal transmission pattern in FIG. 9 and nine combinations of the P-SCH sequence and the synchronization signal transmission pattern in FIG. 12 and is mapped to the S-SCH As one of the above, even if the synchronization signal, that is, the information indicating whether the P-SCH and S-SCH are transmitted in the synchronization signal transmission pattern # 1, # 2, or # 3 is not included, the basic For example, the waveform correlator 102 can determine which of the synchronization signal transmission patterns # 1, # 2, and # 3 is transmitted based on the received P-SCH time interval. Then, the timing detection unit 110 can detect the cell ID or the cell ID group by detecting the P-SCH sequence and the synchronization signal transmission pattern.

  Alternatively, the wireless communication system 1000 defines the synchronization signal transmission pattern in FIG. 9 and the combinations of the eight P-SCH sequences and the synchronization signal transmission pattern in FIG. 13 and is mapped to the S-SCH As one of the cases, the synchronization signal, that is, information indicating whether the P-SCH and S-SCH are transmitted in the synchronization signal transmission patterns # 1, # 2, # 3, and # 4 is included. The S-SCH detection unit 112 also determines, for example, which of the synchronization signal transmission patterns # 1, # 2, # 3, and # 4 is transmitted based on the information element included in the S-SCH. be able to. Then, the timing detection unit 110 can detect the cell ID or the cell ID group by detecting the P-SCH sequence and the synchronization signal transmission pattern.

  Further, for example, information in which the wireless communication system 1000 defines the synchronization signal transmission pattern in FIG. 14 and the combinations of the eight P-SCH sequences and the synchronization signal transmission pattern in FIG. 15 and is mapped to the S-SCH. As one of the elements, even when the synchronization signal, that is, the information indicating whether the P-SCH and S-SCH are transmitted in the synchronization signal transmission pattern # 1 or # 2 is not included, the timing detection is performed. For example, unit 110 can determine whether the transmission is performed in synchronization signal transmission pattern # 1 or # 2 based on the time interval of the received P-SCH. Then, the timing detection unit 110 can detect the cell ID or the cell ID group by detecting the P-SCH sequence and the synchronization signal transmission pattern.

  Alternatively, the wireless communication system 1000 defines a combination of the synchronization signal transmission pattern in FIG. 16 and nine combinations of P-SCH sequences and synchronization signal transmission patterns in FIG. For example, when the synchronization signal, that is, information indicating whether the P-SCH and S-SCH are transmitted in the synchronization signal transmission patterns # 1, # 2, and # 3 is included, the timing For example, the detection unit 110 can determine which of the synchronization signal transmission patterns # 1, # 2, and # 3 is transmitted based on an information element included in the S-SCH. Then, the timing detection unit 110 can detect the cell ID or the cell ID group by detecting the P-SCH sequence and the synchronization signal transmission pattern.

  Alternatively, the wireless communication system 1000 defines the synchronization signal transmission pattern in FIG. 18 and the combinations of the eight P-SCH sequences and the synchronization signal transmission pattern in FIG. 19 and is mapped to the S-SCH. As one of the cases, the synchronization signal, that is, the information indicating whether the P-SCH and the S-SCH are transmitted in the synchronization signal transmission patterns # 1, # 2, # 3, and # 4 is not included. However, the timing detection unit 110 can determine which of the synchronization signal transmission patterns # 1, # 2, # 3, and # 4 is transmitted based on the received P-SCH time interval, for example. . Then, the timing detection unit 110 can detect the cell ID or the cell ID group by detecting the P-SCH sequence and the synchronization signal transmission pattern.

  Next, a synchronization channel transmission method according to the present embodiment will be described.

Synchronization signal generator 209 ₂ selects a sequence of a plurality of synchronizing signals. For example, one of 29 short codes and one of 6 short codes are selected. Then, the synchronization signal generator 209 _2, of the sequence of a plurality of sync signals selected to generate prior information to be reported in advance to the mobile station by the sequence of part of the synchronization signal. For example, prior information indicating a first layer cell ID group that is a part of information for specifying a cell ID group is generated. The generated prior information is transmitted.

Further, the synchronization signal generator 209 _2, of the sequence of the plurality of synchronization signals, the sequence of part of the synchronization signal sequence other than the synchronization signal, and generates a secondary synchronization channel. For example, the secondary synchronization channel which shows the 2nd layer cell ID group which is a part of information which specifies a cell ID group with the 1st layer cell ID group which is a part of information which specifies a cell ID group is produced | generated. A secondary synchronization channel is transmitted. The mobile station detects cell specific information based on the prior information and the secondary synchronization channel.

  Next, a cell search method in the wireless communication system 1000 according to the present embodiment will be described with reference to 22.

  As a first step, the mobile station detects the correlation between the primary synchronization channel sequence and the received signal, and detects the carrier frequency and timing of the primary synchronization channel (S2102, S2104). As a result, the primary synchronization channel sequence number is detected (step S2106). In this first step, the mobile station may obtain the phase difference of the signal and perform frequency offset compensation.

  If the transmission timing and carrier frequency of the primary synchronization channel and the primary synchronization channel sequence number are known, the transmission timing and carrier frequency of the secondary synchronization channel are also known. Frame timing is detected from the cell-specific secondary synchronization channel sequence used in the secondary synchronization channel (S2108). Since a plurality of (for example, two) synchronization channels are typically arranged in one frame, it is necessary to detect the frame timing after timing detection. Also, a cell ID group is detected from the cell-specific secondary synchronization channel sequence (S2110).

  Here, for example, by reporting a part or all of the cell ID group to the mobile station in advance as prior information, the number of unique information candidates to be detected can be reduced, so that the detection accuracy can be improved. As a result, the characteristics can be improved. As prior information, for example, radio frame timing may be notified, or transmission antenna number information may be notified.

  When the base station has a plurality of transmission antennas, the base station notifies the mobile station of the transmission antenna number information on the secondary synchronization channel, and the mobile station transmits the transmission antenna number information (MIMO (Multiple Input Multiple Output) in the second step). (Number of antennas information) may be detected (S2112). In particular, the transmission station number information used for the base station to transmit the broadcast channel may be detected.

  Next, a cell ID is detected using the cell ID group detected in the second step and the primary synchronization channel sequence number detected in the first step (S2114).

  Next, a radio communication system having a base station apparatus and a mobile station according to another embodiment of the present invention will be described.

  The configuration of the wireless communication system according to the present embodiment is the same as that of the wireless communication system described with reference to FIG. The configurations of the base station apparatus and mobile station according to the present embodiment are the same as those of the base station apparatus and mobile station described with reference to FIGS.

  Up to now, as a sequence of synchronization channels, a plurality of, for example, three types of Zadoff-Chu sequences are used for P-SCH, and a binary sequence is used for S-SCH. It is determined to be a combination of short codes (for example, see Non-Patent Documents 5 and 15).

  P-SCH and S-SCH are transmitted every 5 ms. In an inter-station synchronization system in which signals from each cell are synchronized, the mobile station receives signals from a plurality of cells simultaneously. Here, when each cell transmits the same S-SCH every 5 ms, S-SCH interference occurs in every cell every 5 ms.

For example, in the configuration of the wireless communication system described with reference to FIG. 3, each base station apparatus 200 ₁ , 200 _2, and 200 ₃ transmits P− according to the definition of the synchronization signal transmission pattern described with reference to FIG. 8. A subframe number and a slot number in which SCH and S-SCH are transmitted are defined. For example, S-SCH represented by a combination of a plurality of types of P-SCH sequences and two types of short codes is used, and a synchronization signal is transmitted every 5 ms, for example, in subframe number # 1 and subframe number # 6. The In such a case, as described with reference to FIG. 20, in subframe number # 1 and subframe number # 6, the same sequence (short code) is used for the first layer cell ID group used for S-SCH. used.

Specifically, as shown in FIG. 23, in the cell 50 ₁ (cell # 1), two types of short codes used for S-SCH transmitted in subframe number # 1 (frame timing # 1). On the other hand, as the first layer cell ID group, the sequence index (sequence number) is used for the short code of No. 1, and the other of the short codes, specifically, as the second layer cell ID group, the sequence index is No. 2 As the first layer cell ID group used for the S-SCH used for the short code and transmitted in the subframe number # 6 (frame timing # 2), the sequence index is used for the first short code, and the second layer As a cell ID group, its series index It is used to seventh short codes.

In the cell 50 ₂ (cell # 2), as the first layer cell ID group used for the S-SCH transmitted at the frame timing # 1, the sequence index is used for the first short code, and the second layer cell As the ID group, the sequence index is used for the third short code, and as the first layer cell ID group used for the S-SCH transmitted at frame timing # 2, the sequence index is used for the first short code. Then, as the second layer cell ID group, the series index is used for the eighth short code.

  Thus, when the same short code is used as the first layer cell ID group in adjacent cells, the same sequence is used in radio frame timing # 1 and radio frame timing # 2, so radio frame timing 2 The same sequence is used in FIG. Therefore, the maximum collision probability of the S-SCH sequence between 10-ms radio frames is ½. In such a case, in the mobile station 100 located in each cell, the S-SCH from the adjacent cell becomes interference, and it becomes difficult to detect the S-SCH with the short code used by the first layer cell ID group. The short code used by the layer cell ID group makes it difficult to detect S-SCH, and the detection probability of S-SCH is reduced.

As described above, the collision of the same S-SCH sequence from an adjacent cell occurs when the adjacent cell uses a short code having the same sequence number. Therefore, as a method for preventing collision of the same S-SCH sequence from an adjacent cell between two S-SCH symbols in a 10 ms radio frame, there is a short code sequence number mapping method (permutation) (for example, (Refer nonpatent literature 16). In this method, mapping of S-SCH to frame timing # 1 and frame timing # 2 is shown. When mapping of two types of short codes is performed, interference from adjacent cells is considered. That is, in this method, in order to reduce interference in a certain cell from among a combination of at least one of cell ID group which is cell specific information, frame timing, and transmission antenna number information, specifically, The sequence number of each short code is selected so that the collision probability due to the same short code being assigned between adjacent cells is reduced. For example, the assignment of the short code sequence number is determined in advance for each cell ID group so that the S-SCH sequence collision probability between 10-ms radio frames is at most ¼. In this case, transmission antenna number information may also be assigned. For example, as shown in FIG. 24, in cell 50 ₂ (cell # 2), one of two types of short codes used for S-SCH transmitted at frame timing # 2, ie, a first layer cell ID group, The short code whose sequence index (sequence number) is 4 is used. By doing in this way, even when the same short code is used as the first layer cell ID group in adjacent cells, different sequences can be used in the radio frame timing # 2, so that the collision probability can be reduced.

  However, when this method is applied, the neighboring cell information is previously notified by the neighboring cell search in advance, and even if any of the cell ID group, frame timing, and transmission antenna number information is notified, Since it is necessary to select an S-SCH sequence (short code) from all combinations, there is a problem that processing in the base station apparatus is large. That is, there is a problem that the number of S-SCH sequence candidates to be detected is large.

  Therefore, in the base station apparatus 200 according to the present embodiment, as shown in FIG. 25, in the S-SCH sequence mapping method described with reference to FIG. 20, the first layer to which the 0-29th sequence index is attached. The short code belonging to the cell ID group is divided into two and a new 0-15 index is added. This sequence index is called a first layer cell ID group indicator. For example, a Walsh-hadamard sequence can be used as the S-SCH sequence. In the example of FIG. 25, the sequence index 0-31 attached to the Walsh-hadamard sequence is divided into 0-15 and 16-31, which correspond to 0-15 as the first layer cell ID indicator # 1 respectively. The case where it was made to show is shown. In this case, 0-15 of first layer cell ID group indicator # 1 corresponding to sequence index 0-15 is used as the first layer cell ID group used for S-SCH transmitted at radio frame timing # 1. As the first layer cell ID group used for the S-SCH transmitted at the radio frame timing 2, the first layer cell ID group indicators # 1 to 15 corresponding to the sequence index 16-31 are used.

  Also, the short code belonging to the second layer cell ID group with the 0-31 series index is divided into two, and a new 0-15 series index is added. This sequence index is called a second layer cell ID group indicator. For example, a Walsh-hadamard sequence can be used as the S-SCH sequence. The sequence index 0-31 assigned to the Walsh-hadamard sequence is divided into 0-15 and 16-31, and 0-15 is made to correspond to them as the second layer cell ID indicator # 2. In this case, as the second layer cell ID group used for S-SCH transmitted at the radio frame timing # 1, the second layer cell ID group indicator # 2 0-15 corresponding to the sequence index 0-15 is used. As a second layer cell ID group used for S-SCH transmitted at radio frame timing 2, second layer cell ID group indicator # 2 No. 0-15 corresponding to sequence index 16-31 is used. The value of the sequence index takes a value of 0 to 31 for convenience, but it is not essential that 32 types of sequence indexes of short codes belonging to the first cell ID group or the second layer cell ID group are prepared, and the number of sequences as necessary A series index may be reused. For example, from the viewpoint of distinguishing about 170 cell ID groups, the number of sequence indexes of the first cell ID group may be 16, and the sequence index belonging to the second layer cell ID group may be 11 (sequence index of the first layer cell ID group). 16 × second layer cell ID group sequence index 11 = 176).

In FIG. 25, the cell ID group is detected by a combination of the first layer cell ID group indicator # 1 and the second layer cell ID group indicator # 2. For example, the combination of the short code (S _1a ) as the first layer cell ID group indicator # 1 and the short code (S ₂ ) as the second layer cell ID group indicator # 2 at the frame timing # 1, and the frame timing # 2 It is detected by a combination of the short code (S _1b ) as the first cell ID group indicator # 1 and the short code (S ₂ ) as the second layer cell ID group indicator # 2. A combination of {S _1a , S ₂ } and {S _1b , S ₂ } is determined so that a cell ID group collision does not occur. By notifying the advance information regarding the radio frame timing of the target cell or the number of transmission antennas, the cell search procedure can be simplified. For example, when the timing # 1 is notified in advance as the prior information, the S-SCH is detected from the combination of the timing # 2 and the transmission antenna number information. In this case, S-SCH detection is performed from a 16 × 32 combination.

  Further, in order to reduce interference from neighboring cells, first layer cell group ID indicator # 1 and second layer cell group ID indicator # 2 used in radio frame timings # 1 and # 2 used in neighboring cells , A maximum of one is set in advance. From the viewpoint of reducing the collision probability between the first layer cell group ID indicator # 1 and the second layer cell group ID indicator # 2 with the adjacent cell, the first layer cell group ID indicator # 1 and the second layer cell selected by the adjacent cell The group ID indicator # 2 is preferably selected from a different series (short code). Specifically, in cell # 1 and cell # 2, first layer cell ID group indicator # 1 at timing # 1, second layer cell ID group indicator # 1, and first layer cell ID group indicator # 1 at timing # 2. And the short code is selected so that all of the second layer cell ID group indicator # 1 are different. Alternatively, each indicator is predetermined so that at most one is the same.

The synchronization signal control unit 209 ₁ determines the P-SCH sequence number, the P-SCH, and the S based on the cell ID or cell ID group of the cell for which the base station apparatus 200 _m provides communication using Evolved UTRA and UTRAN. and the subframe number and the slot number -SCH is transmitted, determines the synchronization signal transmission timing, and inputs them synchronous signal sequence information and synchronization signal transmission timing information to the synchronization signal generator 209 _2.

Synchronization signal generator 209 _2, based on the synchronization signal sequence information and synchronization signal transmission timing information reported from the synchronization signal control unit 209 _1, generates a synchronization signal sequence. Here, the synchronization signal sequence is either P-SCH or S-SCH.

For example, the synchronization signal generator 209 _2, when generating the S-SCH, to stratify a prepared plurality of types of sequences. Here, when the mobile station performs a cell search, the radio communication system 1000 may notify a part of the hierarchized series as prior information such as neighboring cell information. For example, as a prior information, a cell ID group may be notified, a part of the cell ID group may be notified, a radio frame timing may be notified, or transmission antenna number information may be notified. Alternatively, any one piece of information may be included among information obtained by combining a part of the cell ID group, the cell ID group, the radio frame timing, and the transmission antenna number information. In this way, the number of sequences detected when the mobile station performs cell search can be reduced. Specifically, for example, as shown in FIG. 25, the cell ID group is divided into a plurality of types of sequences, for example, two types of sequences of 32 sequence length and 32 sequence length. In FIG. 25, a sequence 1 having a 32 sequence length is divided into two, a first layer cell ID group with an indicator of 0-15, and a sequence 2 having a 32 sequence length as a sequence 2 having a 32 sequence length. A second layer cell ID group is shown which is divided into two and each marked with an indicator of 0-15. In this case, the synchronization signal control unit 209 ₁ includes a first layer cell ID group indicator # 1 at the timing # 1 in adjacent cells, the second layer cell ID group indicator # 1, first layer cell ID group indicator in the timing # 2 # 1 Then, the synchronization signal sequence is determined so that at least one of the second layer cell ID group indicators # 1 is the same.

  Radio frame timing may be transmitted in first layer cell ID group indicator # 1 (series 1), and transmission antenna number information may be transmitted in second layer cell ID group indicator # 2 (series 2). In the series 1 and the series 2, it is possible to appropriately change whether to transmit the radio frame timing or the transmission antenna number information. For example, when the mobile station is notified of the timing 1 as prior information, the mobile station uses the second layer cell ID group indicator at the timing # 1, the first layer cell ID group indicator # 1 and the second layer cell at the timing # 2. What is necessary is just to detect ID group indicator # 2.

  According to the present embodiment, when any one of cell ID group, frame timing, and transmission antenna number information is notified by neighboring cell information, there are fewer S-SCHs depending on the notified information than when not notified. Detection from the sequence is possible, and the processing load on the base station apparatus can be reduced.

  Also, by mapping system information in consideration of permutation, interference from neighboring cells is randomized when neighboring cells and / or cells in the same base station use the same S-SCH sequence. It becomes possible to improve the detection probability of S-SCH. As a result, cell search time characteristics can be improved. That is, the cell search time can be shortened. For example, in the neighboring cell search, when neighboring cell information is notified to the user apparatus in advance, it is possible to reduce the number of S-SCH sequence candidates to be detected. As a result, the S-SCH detection accuracy can be improved, and the cell search time characteristics can be improved.

  In addition, when prior information is notified to the user apparatus in advance, the number of S-SCH sequence candidates to be detected can be reduced, so that a simple cell search method can be realized.

  In the present embodiment, as shown in FIG. 25, the case has been described in which the first layer cell ID group and the radio frame timing are associated with each other, and the second layer cell ID group and the transmission antenna number information are associated with each other. However, as shown in FIG. 20, even when the second layer cell ID group is associated with the radio frame timing and the number of transmission antennas, the mapping method (S-SCH sequence determination method) in consideration of permutation is used. Application may be made. As described above, S-SCH detection accuracy can be improved by combining permutation and a hierarchical mapping method.

  FIG. 26 is a diagram for explaining another method for determining an S-SCH sequence. The “first code” on the vertical axis in the figure indicates the sequence index of the first short code when, for example, two types of short codes having a sequence length of 31 are used in the S-SCH sequence. In the figure, the “second code” on the horizontal axis indicates the sequence index of the second short code. Although 31 sequence indexes are prepared, as described above, the number of sequence indexes assigned to the first code and the second code may be limited as necessary.

  As shown in the figure, the sequence index of the first short code used at (frame) timing # 1 is selected from the first numerical range (0-13). The sequence index of the second short code used at the timing # 1 is selected from the second numerical range (23-30). The sequence index of the first short code used at timing # 2 after 5 ms from timing # 1 is selected from the second numerical range (23-30). The sequence index of the second short code used at timing # 2 is selected from the first numerical range (0-13).

  Thus, if the numerical ranges of the sequence indexes used at the first and second timings are not overlapped with each other, the number of code candidates when searching for each of the first and second short codes is small, and the search can be performed quickly. In addition, when the sequence index of the first short code is detected, it is advantageous in that it quickly becomes clear that it corresponds to the timing # 1.

  FIG. 27 is a diagram for explaining another method for determining an S-SCH sequence. In the illustrated example, the sequence indexes of the first and second short codes are selected from the same numerical range (0-30). For convenience of explanation, the sequence indexes of the first and second short codes are m and n. In the illustrated example, a combination of m and n is selected so that, for example, mn ≦ Δ or nm ≦ Δ is satisfied. m and n are integers of 0-30, and Δ is an integer of 29 or less. Since the sequence index is selected from a wider numerical range than in the case of FIG. 26, the degree of freedom of the combination of codes used for the secondary synchronization channel is increased, which avoids the collision that is concerned in FIG. It is preferable from the viewpoint of facilitating the process.

  FIG. 28 is a diagram for explaining another method for determining an S-SCH sequence. Also in the illustrated example, the sequence indexes of the first and second short codes are selected from the same numerical range (0-30). However, there is no simple regularity as shown in FIG. 27, and the first and second short codes are variously combined so that the same combination does not occur.

  Next, a method for further ensuring short code collision avoidance will be described.

FIG. 29 shows the same diagram as FIG. 23, and shows a configuration example of the secondary synchronization channel S-SCH transmitted from the adjacent cells # 1 and # 2 to the user apparatus at frame timings # 1 and # 2, respectively. In FIG. 23, the short codes are abbreviated with numbers such as “1”, “2”, etc., but in FIG. 29 the same codes are shown as “M ₁ ”, “M ₂ ”, etc. for convenience of explanation. Has been. The secondary synchronization channel S-SCH transmitted at the timing of frame timing # 1 in cells # 1 and # 2 adjacent to each other is configured by M ₁ and M ₂ × SC ₁ in cell # 1, and M in cell # 2. ₁ and M ₃ × SC ₁ . _M 1, _{M 2} in cell # 1 is used, that is _M 1, _{M 3} in the cell # 2 is used is the same as in FIG. 23. However that scrambling code SC ₁ to the short code # 2 is used it is different from the case of FIG. 23.

FIG. 30 shows a state in which the short code M _i and the scramble code SC _i are associated with each of them. The short code M _i corresponds to the sequence P _i in FIG. 1, and as an example, the sequence is composed of M sequences having a code length of 31. The secondary synchronization channel is, for example, a code having a code length of 62, and is composed of a set of two short codes. The scramble code SC _i may be any appropriate code associated with the short code M _i . It is only necessary to obtain different signs before and after multiplication of the scramble code. As an example, the scramble code SC _i may be an M sequence having a code length of 31.

At the frame synchronization timing # 1 in FIG. 29, the secondary synchronization channel S-SCH transmitted from the cell # 1 is configured by M ₁ and M ₂ × SC ₁ . The secondary synchronization channel S-SCH transmitted from the cell # 2 includes M ₁ and M ₃ × SC ₁ . In this case, since M ₁ is common to the cells # 1 and # 2, a collision occurs.

At frame synchronization timing # 2 5 ms after frame synchronization timing # 1, the secondary synchronization channel S-SCH transmitted from the cell # 1 is configured by M ₂ and M ₁ × SC ₂ . That is, the code used for the short code # 1 at the timing # 1 is used for the short code # 2 at the timing # 2. The code used for short code # 2 at timing # 1 is used for short code # 1 at timing # 2. Then, at the timings # 1 and # 2, the short code # 2 is multiplied by a scramble code corresponding to the code of the short code # 1. At timing # 2, the use of the M ₁ cell # 1 is also the cell # 2 also both the short code # 2, is as it would place a collision. However, in cell # 1, M ₁ is multiplied by scramble code SC ₂ and in cell # 2, it is transmitted after M ₁ is multiplied by scramble code SC _3, so that they have different signs and collide at timing # 2. Can be avoided reliably. The mobile station identifies the first code M _i in the secondary synchronization channel, identifies the scramble code SC _i from the correspondence as shown in FIG. 30, de-scrambles the second code, and scrambles the second second A layer cell ID group indicator is specified. In this way, the mobile station can reliably identify the combination of short codes used for the secondary synchronization channel with few collisions. In the example shown in FIG. 29, two short codes used at timing # 1 are also used at timing # 2 from the viewpoint of reliably reducing collisions. More generally, however, such constraints are not essential. The secondary synchronization channel may be configured by the short code # 1 and the short code # 2 scrambled with the scramble code corresponding to the short code # 1.

  In the above-described embodiment, an example in a system to which Evolved UTRA and UTRAN (also known as Long Term Evolution or Super 3G) is applied has been described. However, the base station apparatus, mobile station apparatus, and synchronization according to the present invention have been described. The channel transmission method can be applied to all systems using orthogonal frequency division multiplexing OFDM (Orthogonal Frequency Division Multiplexing) in the downlink.

  For convenience of explanation, the present invention is described in several embodiments. However, the division of each embodiment is not essential to the present invention, and two or more embodiments may be used as necessary. Although specific numerical examples will be described to facilitate understanding of the invention, these numerical values are merely examples, and any appropriate values may be used unless otherwise specified.

  Although the present invention has been described above with reference to specific embodiments, each embodiment is merely an example, and those skilled in the art will understand various variations, modifications, alternatives, substitutions, and the like. I will. For convenience of explanation, an apparatus according to an embodiment of the present invention has been described using a functional block diagram. However, such an apparatus may be implemented by hardware, software, or a combination thereof. The present invention is not limited to the above-described embodiments, and various variations, modifications, alternatives, substitutions, and the like are included without departing from the spirit of the present invention.

  Hereinafter, embodiments of the disclosed invention are listed as examples.

(1)
A base station apparatus in a wireless communication system comprising a base station apparatus that communicates with a mobile station using an OFDM scheme in the downlink:
Sequence selection means for selecting a plurality of synchronization signal sequences;
Synchronization signal generating means for generating a secondary synchronization channel by using a part of the synchronization signal series and a series of synchronization signals other than the part of the synchronization signal series among the plurality of selected synchronization signal series;
A transmission means for transmitting the secondary synchronization channel;
With
Cell base information is detected by the secondary synchronization channel.

(2)
(1) In the base station apparatus described:
The base station apparatus characterized in that the cell-specific information includes at least one of a cell ID group, a radio frame timing, and transmission antenna number information.

(3)
(2) In the base station device described:
Advance information generating means for generating advance information to be notified to the mobile station in advance by the sequence of the partial synchronization signals;
With
The prior information indicates information indicating a part of the cell ID group, information indicating the cell ID group, information indicating radio frame timing, information indicating the number of transmission antennas, and a part of the cell ID group. One of the information, the information indicating the cell ID group, the information indicating the radio frame timing, and the information combining the information indicating the number of transmission antennas is included.

(4)
In the base station apparatus according to any one of (1) to (3):
The base station device, wherein the sequence selection means selects a sequence different from a sequence selected by a cell adjacent to the base station device.

(5)
In the base station apparatus according to any one of (1) to (3):
The sequence of the synchronization signal is divided into a plurality according to the transmission timing,
The sequence selection means is configured such that, for each transmission timing in a radio frame, at least one sequence of the divided synchronization signal sequences is the same as a sequence selected by a cell adjacent to the base station apparatus. A base station apparatus that selects a series.

(6)
A mobile station apparatus in a wireless communication system including a mobile station apparatus that communicates with a base station apparatus using an OFDM scheme in the downlink:
The base station apparatus selects a plurality of synchronization signal sequences from a plurality of synchronization signal sequences, and selects a part of the synchronization signal sequences and the part of the synchronization signals from the selected plurality of synchronization signal sequences. A secondary synchronization channel is generated by a synchronization signal sequence other than the signal sequence,
Detecting means for detecting cell specific information by the secondary synchronization channel;
A mobile station apparatus comprising:

(7)
(6) In the mobile station apparatus described:
The base station apparatus notifies the advance information in advance by a sequence of the partial synchronization signals,
The mobile station apparatus, wherein the detection means detects cell specific information other than the prior information.

(8)
A synchronization channel transmission method in a wireless communication system including a base station apparatus that communicates with a mobile station using an OFDM scheme in the downlink:
A sequence selection step in which the base station apparatus selects a sequence of a plurality of synchronization signals;
The base station apparatus generates a secondary synchronization channel based on a synchronization signal sequence other than a part of the synchronization signal sequence and the synchronization signal sequence among the selected synchronization signal sequences. Generation step;
A secondary synchronization channel transmission step in which the base station apparatus transmits the secondary synchronization channel;
Have
The mobile station detects the cell specific information using the secondary synchronization channel.

(9)
A base station apparatus used in a mobile communication system,
Means for generating a synchronization channel used in a cell search of a user equipment;
Means for wirelessly transmitting a signal including the synchronization channel;
The synchronization channel has a primary synchronization channel for detecting reception timing, and a secondary synchronization channel including cell-specific information in the previous period,
The secondary synchronization channel is composed of a plurality of different short codes,
A correspondence relationship between a combination of a plurality of short codes, information for identifying a cell, and each of a plurality of candidates for frame synchronization timing is stored in a memory,
A base station apparatus in which a combination of a plurality of short codes is determined so that wireless transmission of a synchronization channel including the same short code from an adjacent cell does not continue over a plurality of frame synchronization timings.

(10)
The secondary synchronization channel is composed of a first short code designated by a first index number and a second short code designated by a second index number;
In the synchronization channel transmitted at the first frame synchronization timing, the first index number is selected from the first numerical range, and the second index number is also selected from the first numerical range. Is,
In the synchronization channel transmitted at the second frame synchronization timing, the first index number is selected from a second numerical range different from the first numerical range, and the second index number is also The base station apparatus according to (9), which is selected from the second numerical range.

(11)
The secondary synchronization channel is composed of a first short code designated by a first index number and a second short code designated by a second index number;
The base station apparatus according to (9), wherein the first and second index numbers are selected from the same numerical range at both the first frame synchronization timing and the second frame synchronization timing.

(12)
The secondary synchronization channel is composed of a combination of a first and a second short code, and the second short code multiplies a certain code by a scramble code associated with the first short code. The base station apparatus according to any one of (9) to (11), wherein the base station apparatus is the code generated in (1).

(13)
The secondary synchronization channel transmitted at the first frame synchronization timing is composed of a first short code specified by the first index number and a second short code specified by the second index number,
A secondary synchronization channel transmitted at the second frame synchronization timing is composed of a first short code specified by the second index number and a second short code specified by the first index number. (12).

(14)
The base station apparatus according to any one of (9) to (13), wherein the short code is configured by an M-sequence code.

(15)
A user apparatus that performs communication via a base station apparatus in a mobile communication system,
Means for receiving a signal including a synchronization channel;
Means for detecting reception timing information from a primary synchronization channel included in the synchronization channel;
Means for identifying identification information of at least a cell from a secondary synchronization channel included in the synchronization channel;
The secondary synchronization channel is composed of a plurality of different short codes,
A correspondence relationship between a combination of a plurality of short codes, information for identifying a cell, and each of a plurality of candidates for frame synchronization timing is stored in a memory,
A user apparatus in which a combination of the plurality of short codes is determined so that wireless transmission of a synchronization channel including the same short code from an adjacent cell does not continue over a plurality of frame synchronization timings.

(16)
The secondary synchronization channel is composed of a first short code designated by a first index number and a second short code designated by a second index number;
In the synchronization channel transmitted at the first frame synchronization timing, the first index number is selected from the first numerical range, and the second index number is also selected from the first numerical range. Is,
In the synchronization channel transmitted at the second frame synchronization timing, the first index number is selected from a second numerical range different from the first numerical range, and the second index number is also The user device according to (15), which is selected from the second numerical range.

(17)
The secondary synchronization channel is composed of a first short code designated by a first index number and a second short code designated by a second index number;
The user apparatus according to (15), wherein the first and second index numbers are selected from the same numerical range at both the first frame synchronization timing and the second frame synchronization timing.

(18)
The secondary synchronization channel is composed of a combination of a first and a second short code, and the second short code multiplies a certain code by a scramble code associated with the first short code. The user device according to any one of (15) to (17), wherein the user device is the code generated in (1).

(19)
The secondary synchronization channel transmitted at the first frame synchronization timing is composed of a first short code specified by the first index number and a second short code specified by the second index number,
A secondary synchronization channel transmitted at the second frame synchronization timing is composed of a first short code specified by the second index number and a second short code specified by the first index number. (18) The base station apparatus described.

(20)
The user apparatus according to any one of (15) to (19), wherein the short code includes an M-sequence code.

(21)
A method used in a mobile communication system, comprising:
A signal including a synchronization channel is wirelessly transmitted from the base station apparatus to the user apparatus;
Detecting a frame synchronization timing candidate from a primary synchronization channel included in the synchronization channel;
Extracting a secondary synchronization channel included in the synchronization channel, identifying a combination of a plurality of short codes, information identifying a cell, and frame synchronization timing;
The secondary synchronization channel is composed of a plurality of different short codes,
A method in which a combination of the plurality of short codes is determined so that wireless transmission of a synchronization channel including the same short code from an adjacent cell does not continue over a plurality of frame synchronization timings.

50 ₁ , 50 ₂ , 50 ₃ ,..., 50 _k cells 100 ₁ , 100 ₂ , 100 ₃ , 100 _n Mobile station 102 Basic waveform correlation unit 104 Synchronization signal replica generation unit 106 Code sequence multiplication unit 108 Upper layer code correlation Unit 110 timing detection unit 112 S-SCH detection unit 200 base station device 202 transmission / reception antenna 204 amplifier unit 206 transmission / reception unit 208 baseband signal processing unit 208 ₁ RLC processing unit 208 ₂ MAC control unit processing unit 208 ₃ encoding unit 208 ₄ data Modulation unit 208 ₅ Multiplexing unit 208 ₆ Serial / parallel conversion unit 208 ₇ Multiplier 208 ₈ Multiplier 208 ₉ Scramble code generation unit 208 ₁₀ Amplitude adjustment unit 208 ₁₁ Synthesis unit 208 ₁₂ Inverse Fourier transform unit 208 ₁₃ CP addition unit 209 ₁ Sync signal controller 209 ₂ sync signal generator 209 ₃ data modulator 09 ₄ serial-parallel converter 209 ₅ multiplier 209 ₆ amplitude adjusting unit 210 call processing unit 212 transmission line interface 300 access gateway apparatus 400 core network 1000 radio communication system

Claims (12)

A base station apparatus used in a mobile communication system,
A generation unit for generating a synchronization channel used in a cell search of the user equipment;
A transmitter that wirelessly transmits a signal including the synchronization channel;
The synchronization channel has a primary synchronization channel for detecting reception timing, and a secondary synchronization channel including cell ID group information,
The secondary synchronization channel is composed of a plurality of different short codes,
A correspondence relationship between a combination of a plurality of short codes and cell ID group information is defined in advance,
The secondary synchronization channel is composed of a first short code designated by a first index number and a second short code designated by a second index number;
2. Base station apparatus characterized in that second index number−first index number ≦ Δ (Δ is a positive integer).   The base station apparatus according to claim 1, wherein the first and second index numbers are selected from the same numerical range.   The base station apparatus according to claim 1 or 2, wherein one of the first short code and the second short code is multiplied by a scramble code associated with the other. The secondary synchronization channel transmitted at the first frame synchronization timing is composed of a first short code specified by the first index number and a second short code specified by the second index number,
In the secondary synchronization channel transmitted at the second frame synchronization timing, the relationship between the first index number and the second index number in the secondary synchronization channel transmitted at the first frame synchronization timing is switched. The base station apparatus according to any one of claims 1 to 3.   The first frame synchronization timing is included in a predetermined subframe among frames composed of a plurality of subframes, and the second frame synchronization timing includes the first frame synchronization timing among the frames. The base station apparatus according to claim 4, wherein the base station apparatus is included in a subframe subsequent to the subframe.   The base station apparatus according to any one of claims 1 to 5, wherein the short code includes an M-sequence code. A synchronization channel transmission method used in a mobile communication system, comprising:
Generating a synchronization channel used in a cell search of a user equipment;
Wirelessly transmitting a signal including the synchronization channel;
The synchronization channel has a primary synchronization channel for detecting reception timing, and a secondary synchronization channel including cell ID group information,
The secondary synchronization channel is composed of a plurality of different short codes,
A correspondence relationship between a combination of a plurality of short codes and cell ID group information is defined in advance,
The secondary synchronization channel is composed of a first short code designated by a first index number and a second short code designated by a second index number;
The second index number minus the first index number ≦ Δ (Δ is a positive integer).   8. The synchronization channel transmission method according to claim 7, wherein the first and second index numbers are selected from the same numerical range.   9. The synchronization channel transmission method according to claim 7, wherein one of the first short code and the second short code is multiplied by a scramble code associated with the other. The secondary synchronization channel transmitted at the first frame synchronization timing is composed of a first short code specified by the first index number and a second short code specified by the second index number,
In the secondary synchronization channel transmitted at the second frame synchronization timing, the relationship between the first index number and the second index number in the secondary synchronization channel transmitted at the first frame synchronization timing is switched. A synchronization channel transmission method according to any one of claims 7 to 9.   The first frame synchronization timing is included in a predetermined subframe among frames composed of a plurality of subframes, and the second frame synchronization timing includes the first frame synchronization timing among the frames. The synchronization channel transmission method according to claim 10, wherein the synchronization channel transmission method is included in a subframe after the subframe. The synchronization channel transmission method according to claim 7, wherein the short code is configured by an M-sequence code.

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