JP2008103959A - Ofdm transmitter, ofdm receiver, base station device, mobile station apparatus, ofdm communications system, and cell search method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform a synchronization channel with little system overhead and high detection characteristics, and cell search by using it, when a GCL sequence is mapped to a reference signal sequence. <P>SOLUTION: An OFDM transmitter 10 which transmits a radio signal by an OFDM method comprises: a control signal generating part 12 for generating a synchronous channel signal including at least a reference signal used for propagation path presumption, a scrambling code signal and a group scrambling index, and/or a cell peculiar information index (cell composition ID); and a channel mapping part 13 for carrying out the multiplication of the scrambling code to an OFDM signal, while mapping the reference signal and a synchronous channel signal on a predetermined subcarrier. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a base station apparatus, a mobile station apparatus, an OFDM communication system, and a cell search method that perform radio communication using the OFDM method.

  In 3GPP (3rd Generation Partnership Project), a W-CDMA (Wideband Code Division Multiple Access) method is standardized as a third generation cellular mobile communication method, and services are started sequentially. One of the W-CDMA systems is an FDD spread spectrum system having a 5 MHz radio frequency bandwidth. Each radio physical channel is distinguished by a spread code, code-multiplexed, and transmitted using the same radio frequency bandwidth.

  In the W-CDMA system, a radio link from a mobile station to a base station (hereinafter referred to as “uplink”) and a radio link from the base station to the mobile station (hereinafter referred to as “downlink”). There is. A W-CDMA downlink radio channel is divided into a control channel and a traffic channel TCH (Traffic Channel: user data channel). The control channel is divided into a common control channel and a user dedicated control channel. The common control channel includes a common pilot channel CPICH (Common Pilot Channel) that is a reference signal RS (Reference Signals), a synchronization channel SCH (Synchronization Channel), and a broadcast channel BCH (Broadcast Channel) (for example, non-patent literature). 1 and 2).

  Also, the evolution of third generation radio access (Evolved Universal Terrestrial Radio Access: hereinafter referred to as “EUTRA”) and the evolution of the third generation radio access network (hereinafter referred to as “Evolved Universal Terrestrial Radio Access: TR”). ) Is being considered. An OFDMA (Orthogonal Frequency Division Multiplexing Access) scheme has been proposed as a downlink of EUTRA. As the EUTRA technology, an adaptive modulation and coding scheme AMCS (hereinafter referred to as “AMCS”) based on OFDMA and adaptive radio link control (link adaptation) such as channel coding is used. Technology is applied.

(1) Description of EUTRA Downlink Radio Frame Configuration Regarding the arrangement of downlink radio channels in the OFDMA scheme, time division multiplexing TDM (using a frequency axis (subcarrier) and time axis (OFDM symbol) resource of the OFDM signal is used. Time division multiplexing (Time Division Multiplexing), Frequency Division Multiplexing FDM (Frequency Division Multiplexing), or a method of multiplexing only in TDM / FDM is proposed. Further, according to a technical specification document created by an international meeting of 3GPP EUTRA technical study, a configuration of a downlink radio frame and a radio channel mapping method that is a method of arranging each radio channel in a radio frame have been proposed (for example, Non-Patent Document 3).

  FIG. 10 is a diagram for explaining an example of a downlink radio frame configuration and radio channel mapping of EUTRA assumed based on the proposal of 3GPP. A downlink radio frame is composed of a two-dimensional radio resource block RB (Resource Block) with a frequency bandwidth Bch, which is a cluster of a plurality of subcarriers in the frequency axis direction, and a subframe SF (Sub-frame) in the time axis. It is configured.

  For example, on the frequency axis, the entire downlink spectrum (base station specific system frequency bandwidth BW) is 20 MHz, the RB frequency bandwidth Bch is 180 kHz, the subframe SF is 0.5 ms, and the subcarrier frequency bandwidth Bsc is When 15 kHz and one radio frame are set to 10 ms, in the downlink, the radio frame includes 1000 RBs, one RB includes 12 subcarriers, and 600 subbands in the entire 20 MHz band. Carrier included. Ts represents the OFDM symbol length.

  As shown in FIG. 10, the reference signal RS, that is, the common pilot channel CPICH is mapped to the head of each subframe SF, and the broadcast channel BCH and the synchronization channel SCH are one at the head of each radio frame and / or radio. Multiple mappings are made in the frame. The remaining part of each RB is used as a traffic channel TCH and allocated to each mobile station using AMCS.

  Also, EUTRA / EUTRAN technical requirements (for example, see Non-Patent Document 4) have been proposed, and spectrum flexibility (spectrum flexibility) for fusion and coexistence with existing 2G (2nd Generation) and 3G (3rd Generation) services. ), And support for spectrum allocation of different sizes (frequency bandwidth, eg, 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, 20 MHz) is required.

  Also, since the base frequency RF (Radio Frequency) center frequency of the EUTRA / EUTRAN system is shared with the frequency spectrum of the existing W-CDMA system, the RF center frequency and channel number UARFCN (UTRA Absolute) used in W-CDMA are used. It is necessary to match with Radio Frequency Channel Number (see Non-Patent Document 5). As shown in the EUTRA contribution document (see Non-Patent Document 6), the common control channel (synchronization channel SCH and broadcast channel BCH) is centered on the base station RF center frequency fc due to the frequency raster (Frequency Raster: 200 kHz). In addition, a method of mapping to the entire band or a partial band of the maximum system frequency bandwidth BW specific to the base station and symmetrical to the frequency axis is presented.

  FIG. 11 is a diagram illustrating a mapping example of the synchronization channel SCH. When the base station-specific maximum system frequency bandwidth BW has frequency bandwidths of 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, and 20 MHz, respectively, the synchronization channel SCH has a frequency centered on the RF center frequency fc of the base station. It is symmetrical with respect to the axis and is mapped to a band of 1.25 MHz (see Non-Patent Document 3, Section 7.1.2.4 Cell search).

  FIG. 14 is a diagram illustrating a mapping example of the reference signal RS in one RB of the downlink radio frame configuration of EUTRA illustrated in FIG. The first reference symbol RS1 and the second reference symbol RS2 are included, and are mapped to the first OFDM symbol and the fifth OFDM symbol at intervals of six subcarriers, respectively (Non-Patent Document 3, section). (See 7.1.1.2.2 Downlink reference-signal structure).

  Similar to the W-CDMA scheme, in order to represent interference reduction and cell physical layer index (Cell ID: hereinafter referred to as “cell ID”) of adjacent cells, in the downlink radio frame of EUTRA, it differs depending on the base station. A scrambling code SC (Scramble Code) is applied. FIG. 13 shows an example of scrambling code SC mapping, which is an example of arranging scrambling code SC on each subcarrier. In accordance with the maximum system frequency bandwidth BW unique to the base station, one OFDM symbol length is covered with one cycle of scrambling code SC (multiplication with scrambling code SC), and one subcarrier is provided for each OFDM symbol timing Ts. Is shifted by one code phase.

  Here, an index of the scrambling code SC (hereinafter referred to as “SCID”) indicates a physical layer index (eNode_B ID: hereinafter referred to as “base station ID”) unique to the base station. The cell ID is indicated by a combination of the SCID and the reference signal RS sequence index (hereinafter referred to as “RSID”) (see Non-Patent Document 7).

(2) Description of Reference Signal RS Reference signal RS inserted in a downlink radio frame of EUTRA is a downlink radio channel quality measurement (downlink-channel-quality measurement) for applying AMCS technology, a mobile station Used for downlink channel estimation for detection / detection at the UE for correlation demodulation or correlation detection in the device, and initial synchronization and cell search (Non-patent Document 3) , Section 7.1.1.2.2 Downlink reference-signal structure See).

  Different reference signals RS are assigned to cells in order to realize downlink radio propagation path quality measurement, downlink propagation path estimation and initial synchronization / cell search using the reference signal RS. A reference signal RS sequence (hereinafter referred to as a “reference sequence or RS sequence”) of an orthogonal code (sector-specific official sequence) has been proposed (see Non-Patent Document 7). In addition, GCL sequences (or GCL codes) having different GCL (Generalized Chirp Like) sequence indexes (hereinafter referred to as “GCLID”) are mapped to reference signals RS of different cells, and different reference sequences are generated in different cells. Has also been proposed (see Non-Patent Document 8). The GCL sequence can be expressed by Equation (1).

Here, _NG is the length of the GCL sequence and is a prime number, and u indicates GCLID. That, GCL sequence of length _{N G,} it is _N G -1 amino GCLID (GCL sequence type). When mapping to the first reference symbol having the length N _d (N _d ≦ _NG ) in FIG. 14, the kth GCL sequence element corresponds to the R1 and kth reference signal RS element. Here, when one base station apparatus is divided into a plurality of sectors, one sector is called a “cell”.

Table 1 shows the reference sequence when the reference signal RS interval is 6 subcarriers for the system frequency bandwidths BW (for example, 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, and 20 MHz) of different base station apparatuses. length _{N d} and GCL sequence showing the relationship between the length _{N G.}

  By using the good auto-correlation and cross-correlation characteristics of the reference sequence in the frequency domain, good downlink radio channel quality measurement and downlink channel estimation characteristics can be obtained.

FIG. 14 shows an example of reference sequence mapping when the base station apparatus has a plurality of transmission antennas (1 to 4). Table 2 shows a GCL sequence mapping method according to the number of transmission antennas of the base station apparatus to each reference signal RS of the first and second reference symbols.

(3) Description of group scrambling GS In order to perform a cell search using the reference signal RS, it is necessary to associate the GCLID mapped to the reference signal RS with the cell ID (c = 1, 2,..., C). is there. As shown in Table 1, depending on the system frequency bandwidth BW of the base station apparatus, the total number of GCLIDs differs, and the total number (U) of RSIDs (u = 1, 2,..., U) corresponding to the GCLIDs also differs. As the system frequency bandwidth BW of the base station apparatus decreases, the length of the reference sequence decreases, so the total number (U) of RSIDs also decreases.

  Therefore, using the good auto-correlation and cross-correlation characteristics of the reference sequence in the frequency domain, good downlink radio channel quality measurement and downlink channel estimation characteristics are obtained, and at the same time, the total number of cell IDs (C) In order to increase the number of scrambling codes SC, a plurality of scrambling codes SC can be reused (repeated) in the local service area instead of assigning different scrambling codes SC to the base station apparatus as in the W-CDMA system. Base station apparatuses are grouped into one group and a scrambling code SC having one SCID (g = 1, 2,..., G) is assigned to introduce a group scrambling GS (Group Scrambling) concept. Base station apparatus group index, that is, a group scrambling GS index (v = 1, 2,..., V, hereinafter referred to as “GSID”) corresponding to SCID (g) and one cell in the base station apparatus group A method of expressing the cell ID (c) of the entire system by a combination of IDs, that is, RSID (u) has been proposed (see Non-Patent Document 8).

  FIG. 15 shows an example of a method for expressing a cell ID (c) by a combination of GSID (v) and RSID (u). In FIG. 15, three cells are included in one base station apparatus, and 12 RSIDs (u) are allocated to one GSID (v). A total of 4 GSIDs (v = 1, 2, 3, 4) and 12 RSIDs (u = 1, 2,..., 12) represent 48 cell IDs (c).

That is, the total cell ID C of the entire system is expressed by Equation (2).
C = V · U (2)
By introducing this group scrambling GS, for example, even when the system frequency bandwidth BW of the base station apparatus is 1.25 MHz, a total of 48 cell IDs (c) are represented by a total of 4 GSIDs and a total of 12 RSIDs. be able to.

(4) Description of the synchronization channel SCH structure The synchronization channel SCH inserted in the downlink radio frame of EUTRA is used for initial synchronization of OFDM received signals, cell search (initial cell search, standby cell search, in-communication cell search), etc. It is used. The synchronization channel SCH includes carrier frequency offset synchronization, OFDM symbol timing synchronization, radio frame timing synchronization, direct or indirect information of the cell ID (c), the number of transmission antennas of the base station apparatus, a system frequency bandwidth BW specific to the base station apparatus Cell-specific information index (w = 1, 2,..., W, hereinafter “cell” such as broadcast channel frequency bandwidth, OFDM symbol CP (Cyclic Prefix) length, radio frame timing, etc. This is referred to as a “configuration ID”. The cell information ID (y = 1, 2, 3,..., Y, Y = C · W, where the direct / indirect information of the cell ID (c) and the cell configuration ID (w) are combined. And the indirect information together are referred to as cell ID (c)).

The configuration of the synchronization channel SCH is
(1) Initial synchronization characteristics such as carrier frequency offset and OFDM symbol timing detection accuracy, detection time,
(2) cell search characteristics such as detection probability and detection time of the cell information ID (y);
(3) System overhead (ratio of resources occupied by the synchronization channel SCH and total radio frame resources),
(4) Application of EUTRA to TDD (Time Division Duplex) system,
(5) Depends on factors such as the amount of calculation of signal processing in the mobile station apparatus.

  Various synchronization channel SCH configurations capable of expressing a large amount of cell information ID (y) with a small number of synchronization channel SCH resources have been proposed while taking into consideration the improvement of initial synchronization characteristics, the improvement of cell search characteristics, and the processing amount of the mobile station apparatus. (See Non-Patent Document 3, Section 7.1.2.4 Cell search, Non-Patent Document 9).

(5) Explanation on Cell Search Procedure The mobile station device needs to perform a cell search for searching for a cell to which a radio link is to be connected when the power is turned on, at the time of handover, or when waiting for communication. In the EUTRA system, a three-stage cell search procedure similar to the W-CDMA method has been proposed (see Non-Patent Document 3, Section 7.1.2.4 Cell search, Non-Patent Document 9).

  FIG. 16 shows an example of a cell search procedure in the EUTRA system. In step 1 (R1, first stage), a carrier frequency offset corresponding to the maximum power synchronization channel SCH by the autocorrelation or cross-correlation processing in the time domain is applied to the received signals of the plurality of synchronization channels SCH, OFDM symbols Timing detection is performed. In step 2 (R2, second stage), the carrier frequency offset and OFDM symbol timing correction is performed based on the detection result, the OFDM signal is demodulated (CP removal, DFT conversion), and the synchronization sequence mapped to the synchronization channel SCH in the frequency domain An index (s = 1, 2, 3,..., S, hereinafter referred to as “SCHID”) is detected, and cell information ID (y) associated with SCHID (s) is identified.

Indirect information of the cell ID (c), for example, a scrambling group SG (Scramble Group) index (h = 1, 2, 3,..., H, etc. used in the W-CDMA system shown in FIG. , Referred to as “SGID”), in step 3 (R3, third stage), a plurality of SCIDs (g = 1, 2, 3,..., G) indicating SGID (h) are further identified. For example, when one SGID in the total number 64 (H = 64) indicates 8 SCIDs, the descrambling love ring process is performed 8 times on the received reference signals RS, and the reference of the maximum power is obtained. Using the signal RS, 512 base station IDs (here, SCID (g) is equal to the base station ID) are identified, and further, the reference signal RS with the maximum power is detected. Cell ID (c) is identified.
3GPP TS 25.211, V7.0.0 (2006-03), Physical channels and mapping of transport channels on physical channels. http: // www. 3 gpp. org / ftp / Specs / html-info / 25-series. htm Keiji Tachikawa, “W-CDMA mobile communication system”, ISBN4-621-04894-5, P103, P115, etc. 3GPP TR (Technical Report) 25.814, V7.0. 0 (2006-06), Physical Layer Aspects for Evolved UTRA. http: // www. 3 gpp. org / ftp / Specs / html-info / 25814. htm 3GPP TR (Technical Report) 25.913, V7.3.0 (2006-03), Requirements for evolved Universal Terrestrial Radio Access (UTRA) and Universal TerrestR. http: // www. 3 gpp. org / ftp / Specs / html-info / 25913. htm 3GPP TS 25.101, V7.4.0 (2006-06), User Equipment (UE) radio transmission and reception (FDD), http: // www. 3 gpp. org / ftp / Specs / html-info / 25-series. htm R1-050592, “Physical Channel Concept for Scalable Bandwidth in Evolved UTRA Downlink”, 3GPP TSG RAN WG1 Ad Hoc on LTE, w. 200 p. 3 gpp. org / ftp / tsg_ran / WG1_RL1 / TSGR1_AH / LTE_AH_June-05 / Docs / R1-050704, “Orthogonal Common Pilot Channel and Scrambled Code in Evolved UTRA Downlink”, 3GPP TSG RAN WG1 # 42 on LTE, London, UK, August 29, August, UK, August 29. 3 gpp. org / ftp / tsg_ran / WG1_RL1 / TSGR1_42 / Docs / R1-061723, “Downlink Reference signal sequence design”, 3GPP TSG RAN1 on LTE, Cannes, France, June 27-30, 2006, http: // www. 3 gpp. org / ftp / tsg_ran / WG1_RL1 / TSGR1_AH / LTE_AH_June-06 / Docs / R1-061662, “SCH Structure and Cell Search Method for E-UTRA Downlink”, 3GPP TSG RAN WG1 LTE Ad Hoc, Cannes, France, 27-30 June, t. 3 gpp. org / ftp / tsg_ran / WG1_RL1 / TSGR1_AH / LTE_AH_June-06 / Docs / T.A. Keller, L.M. Piazzo, P.M. Mandarini, L.M. Hanzo, “Orthogonal Frequency Division Multiplex Synchronization Techniques for Frequency-Selective Fading Channels”, IEEE Journal of Ven Sel. 19, NO. 6, June 2001 page (s): 999-1007. R1-061663, “Cell Search Time Performance of 3-Step Cell Search Method in Multi-Cell Environment”, 3GPP TSG RAN WG1 LTE Ad Hoc, Cannes, France 200 / w. 3 gpp. org / ftp / tsg_ran / WG1_RL1 / TSGR1_AH / LTE_AH_June-06 / Docs / R1-051329, “Cell Search and Initial Acquisition for OFDM Downlink”, 3GPP TSG RAN WG1 # 43, Cannes, Seoul, Korea, Nov 7-11, 2005, http: //www.R1-051329, “Cell Search and Initial Acquisition for OFDM Downlink”. 3 gpp. org / ftp / tsg_ran / WG1_RL1 / TSGR1_43 / Docs / R1-061665, “Broadcast Channel Structure for E-UTRA Downlink”, 3GPP TSG RAN WG1 LTE Ad Hoc, Cannes, France, 27-30 June, 2006 / htw. 3 gpp. org / ftp / tsg_ran / WG1_RL1 / TSGR1_AH / LTE_AH_June-06 / Docs /

  However, in the above Non-Patent Document 8, in the EUTRA / EUTRAN system, good downlink radio propagation path quality measurement and downlink propagation path using the good auto-correlation and cross-correlation characteristics of the reference sequence in the frequency domain. Group scrambling GS using scrambling code SC has been proposed in order to increase the total number (C) of cell IDs by mapping a GCL sequence that provides estimated characteristics to a reference sequence. The configuration of the synchronization channel SCH and the cell search procedure when mapped are not presented.

  Further, for different system frequency bandwidths (for example, 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, 20 MHz) base station apparatuses, the total number of cell IDs (C) decreases as the system frequency bandwidth decreases. There is a problem, and a configuration of the synchronization channel SCH suitable for different system frequency bandwidths is desirable.

  Furthermore, in the case of a mobile station apparatus having a transmission / reception capability of 10 MHz and 20 MHz frequency bandwidths with respect to a base station apparatus having a 20 MHz system frequency bandwidth, the configuration of the optimal reference signal RS and the synchronization channel SCH, and this is suitable. Cell search method is not presented.

  The present invention has been made in view of such circumstances, and using a reference sequence, a synchronization channel SCH having a small system overhead, a high detection rate and a short detection time, and a cell search using the synchronization channel SCH An object of the present invention is to provide a base station apparatus, a mobile station apparatus, an OFDM communication system, and a cell search method that can perform the above.

  (1) In order to achieve the above object, the present invention takes the following measures. That is, the OFDM transmission apparatus of the present invention is an OFDM transmission apparatus that transmits a radio signal by OFDM, and at least a reference signal used for channel estimation, a scrambling code signal, a group scrambling index, and / or a cell-specific A control signal generation unit that generates a synchronization channel signal including an information index (cell configuration ID), and a channel mapping that maps the reference signal and the synchronization channel signal to a predetermined subcarrier and multiplies the OFDM signal by the scrambling code And a section.

  With this configuration, by using the good autocorrelation and cross-correlation characteristics of the reference signal sequence in the frequency domain, while obtaining good downlink radio channel quality measurement and downlink channel estimation characteristics, a large number of cell IDs ( At the same time as realizing c), it is possible to realize a configuration of the synchronization channel SCH having a smaller system overhead and higher detection characteristics than the conventional method.

  (2) In the OFDM transmitter of the present invention, the control signal generator generates a plurality of different synchronization channel signals including cell specific information indexes (cell configuration IDs) indicating different system frequency bandwidths. It is characterized by that.

  With this configuration, it is possible to use an optimum synchronization channel signal for different system frequency bandwidths.

  (3) Further, the OFDM receiver of the present invention is an OFDM receiver that receives a radio signal transmitted by the OFDM method. From the received signal, at least a reference signal used for channel estimation, a scrambling code signal, And a control signal extraction unit that extracts a synchronization channel signal including a group scrambling index and / or a cell specific information index (cell configuration ID), a reference sequence index (RSID) of the extracted reference signal, and the extracted And a cell search unit for calculating a cell physical layer index (cell ID) based on the group scrambling index of the synchronization channel signal.

  With this configuration, by using the good autocorrelation and cross-correlation characteristics of the reference signal sequence in the frequency domain, while obtaining good downlink radio channel quality measurement and downlink channel estimation characteristics, a large number of cell IDs ( At the same time as realizing c), it is possible to realize a configuration of the synchronization channel SCH having a smaller system overhead and higher detection characteristics than the conventional method.

  (4) In the OFDM receiver of the present invention, the cell search unit has a maximum reception power from a time / frequency synchronization unit that detects a carrier frequency offset and OFDM symbol timing, and a plurality of synchronization channel signals. Based on the reference signal, a synchronization sequence index (SCHID) identifying unit that identifies a synchronization sequence index (SCHID) mapped to the synchronization channel and outputs a group scrambling index and / or a cell specific information index (cell configuration ID) A reference signal processing unit that outputs received power information of a reference signal and a reference sequence index (RSID), a group of the extracted synchronization channel signal, the reference sequence index, and Multiplying the flop scrambling index is characterized a multiplying unit for calculating a cell physical layer index (cell ID), in that it comprises.

  With this configuration, it is possible to perform cell search more easily than in the past, and it is possible to reduce the amount of signal processing and power consumption.

  (5) In the OFDM receiver according to the present invention, the control signal extraction unit extracts a plurality of different synchronization channel signals including cell specific information indexes (cell configuration IDs) indicating different system frequency bandwidths. The synchronization sequence index (SCHID) identifying unit identifies a first group scrambling index and a cell specific information index (cell configuration ID) included in the first synchronization channel signal, and this cell specific information index ( Based on the cell configuration ID, the presence / absence of a subsequent synchronization channel signal is determined. If there is a subsequent synchronization channel signal, a group scrambling index and a cell specific information index (cell configuration) are further added to the subsequent synchronization channel signal. ID) is identified.

  With this configuration, it is possible to use an optimum synchronization channel signal for different system frequency bandwidths.

  (6) Moreover, the base station apparatus of this invention is equipped with the OFDM transmitter of Claim 1 or Claim 2, It is characterized by the above-mentioned.

  With this configuration, by using the good autocorrelation and cross-correlation characteristics of the reference signal sequence in the frequency domain, while obtaining good downlink radio channel quality measurement and downlink channel estimation characteristics, a large number of cell IDs ( At the same time as realizing c), it is possible to realize a configuration of the synchronization channel SCH having a smaller system overhead and higher detection characteristics than the conventional method.

  (7) Moreover, the mobile station apparatus of this invention is equipped with the OFDM receiver in any one of Claim 3-5. It is characterized by the above-mentioned.

  With this configuration, by using the good autocorrelation and cross-correlation characteristics of the reference signal sequence in the frequency domain, while obtaining good downlink radio channel quality measurement and downlink channel estimation characteristics, a large number of cell IDs ( At the same time as realizing c), it is possible to realize a configuration of the synchronization channel SCH having a smaller system overhead and higher detection characteristics than the conventional method.

  (8) Further, the OFDM communication system of the present invention is composed of the base station device according to claim 6 and the mobile station device according to claim 7. Yes.

  With this configuration, when a GCL sequence having a different GCLID is mapped to the reference signal sequence of each cell, a good downlink radio propagation path can be obtained using the good autocorrelation and cross-correlation characteristics of the reference signal sequence in the frequency domain. While obtaining a large number of cell IDs (c) while obtaining the quality measurement and downlink propagation path estimation characteristics, it is possible to realize a configuration of a synchronization channel SCH having less system overhead and higher detection characteristics as compared with the conventional method.

  (9) Further, the cell search method of the present invention includes at least a reference signal used for channel estimation, a scrambling code signal, a group scrambling index, and a group scrambling index on the transmission side of a radio communication system that transmits and receives radio signals by OFDM. And / or generating a synchronization channel signal including a cell-specific information index (cell configuration ID), mapping the reference signal and the synchronization channel signal to a predetermined subcarrier, and multiplying the OFDM signal by the scrambling code for transmission Cell search method, and at the receiving side, at least a reference signal used for propagation path estimation, a scrambling code signal, a group scrambling index, and / or cell-specific information input from a received signal. Cell channel layer index based on a reference sequence index (RSID) of the extracted reference signal and a group scrambling index of the extracted synchronization channel signal. (Cell ID) is calculated.

  With this configuration, by using the good autocorrelation and cross-correlation characteristics of the reference signal sequence in the frequency domain, while obtaining good downlink radio channel quality measurement and downlink channel estimation characteristics, a large number of cell IDs ( At the same time as realizing c), it is possible to realize a configuration of the synchronization channel SCH having a smaller system overhead and higher detection characteristics than the conventional method.

  According to the present invention, a mobile station device of a mobile station class having a different frequency bandwidth (for example, 10 MHz, 20 MHz) and a different system frequency bandwidth (for example, 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, 20 MHz) In a mobile communication system using a base station apparatus, a GCL sequence having a different GCLID is mapped to a reference signal RS of each cell, a reference sequence is generated, and good autocorrelation and cross-correlation characteristics of the reference sequence in the frequency domain are used. In addition, while achieving good downlink radio channel quality measurement and downlink channel estimation characteristics, it achieves a large number of cell IDs (c), and at the same time has less system overhead and higher detection characteristics than the conventional method The configuration of the synchronization channel SCH can be realized.

  In addition, in order to increase the cell ID (c), the group scrambling corresponding to the scrambling code is used, and the cell ID (c) is a combination of the group scrambling index (v) and the RSID (u) which is the GCLID. Compared to the conventional method, the number of transmission antennas of the base station apparatus, the broadcast channel frequency bandwidth, the CP length of the OFDM symbol, and the radio frame timing are compared with the conventional method. Since the cell specific information (w) can be expressed, the efficient use of the synchronization channel SCH resource can be realized.

  In addition, for different system frequency bandwidths (for example, 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, 20 MHz) base station apparatuses, the cell ID total number (C), the cell configuration ID total number (W), and the SCHID total number (S ), Group scrambling index total number (V), RSID total number (U), and other common system parameters can be realized.

  In addition, in the case of a mobile station device having transmission / reception capabilities of 10 MHz and 20 MHz frequency bandwidths with respect to a base station device having a 20 MHz system frequency bandwidth, the configuration of the optimal reference signal RS and the synchronization channel SCH, and this is suitable. A cell search method can be realized.

  Furthermore, the cell search method adapted to the proposed synchronization channel SCH makes the identification of the cell specific information (w) and the cell ID (c) easier than the conventional method, and reduces the signal processing amount and power consumption of the mobile station apparatus. it can.

(Embodiment 1)
In the first embodiment of the present invention, the configuration of the synchronization channel SCH including the group scrambling GS index GSID (v) and the cell configuration ID (w), the cell configuration ID (w), the GSID (v), and the reference sequence index RSID ( A cell search procedure for identifying the cell ID (c) based on the identification of u) is proposed.

(A) Configuration of transmission unit of base station apparatus according to Embodiment 1 FIG. 1 shows a configuration of a transmission unit of a base station apparatus according to the present invention. FIG. 1 shows a transmission unit of one cell. As shown in FIG. 15, when one base station apparatus is configured by three cells, three transmission units shown in FIG. 1 are provided. Further, as shown in Table 2, when a plurality of (1 to 4) transmission antennas are configured in one cell, a plurality (1 to 4) transmission units corresponding to the plurality of transmission antennas shown in FIG. Can be configured. Here, as an example, a transmission unit corresponding to one transmission antenna for one cell will be described.

  The transmission unit 10 includes a serial-parallel conversion (S / P) unit 11, a control signal generation unit 12, a channel mapping unit 13, an IDFT conversion unit (Inverse Discrete Fourier Transform) 14, a parallel-serial conversion unit (P / S) 15, CP (Cyclic Prefix) insertion unit 16, digital / analog signal conversion unit (DAC) 17, radio unit (TX) 18, and transmission antenna 19. The transmitter 10 constitutes an OFDM transmitter.

  The transmission data of each mobile station shown in FIG. 10 (for example, mobile stations MS 1, 2 and 3 in FIG. 10) is input to the serial / parallel converter (S / P) 11, and after parallel data conversion, is transmitted to the channel mapping unit 13. Entered. The channel mapping unit 13 uses the CQI measurement result fed back from the mobile station device (the channel estimation / output of the CQI measurement unit 30 of the mobile station device shown in FIG. 3), and the radio propagation path of the mobile station device. Adaptive modulation (AMCS) is performed to select a radio resource block RB suitable for the transmission, and transmission data is mapped to a predetermined RB. The user data mapped to the traffic channel TCH generates an OFDM signal by the IDFT conversion unit 14, and passes through the parallel / serial conversion unit (P / S) 15, the CP insertion unit 16, and the digital / analog signal conversion unit (DAC) 17. Input to the radio unit (TX) 18. In the radio unit (TX) 18, the signal is transmitted as a downlink signal by the transmission antenna 19 to the mobile station apparatus through the filtering process of the OFDM signal, the frequency conversion, and the like.

  On the other hand, a control signal such as a reference signal RS, a scrambling code SC signal, a synchronization channel SCH signal, a broadcast channel BCH signal, and a shared / individual control signal is generated by the control signal generation unit 12 and input to the channel mapping unit 13. The channel mapping unit 13 maps each control signal to the common control channel as shown in FIG.

(1) generating a reference signal RS of the reference signal RS, as shown in Table 1, the system frequency bandwidth BW of the predefined base station apparatus, the length N _d of the reference sequence is defined, RSID Total (U) Has been determined. For example, the system frequency bandwidth BW of the base station apparatus in the case of 20 MHz, has a total 1201 subcarriers, by arranging the reference signals RS at six sub-carrier interval, the length N _d of the reference sequence 200 becomes When the GCL sequence length (N _G ) is 211, a total of 210 RSID (u) is obtained.

The control signal generation unit 12 includes a GCL sequence length (N _G ) designated from the control data, or N _G , RSID (u), or cell ID (c) calculated from information such as the system frequency bandwidth BW of the base station device. ) And the like calculated from information such as) are substituted into equation (1), a predetermined GCL sequence is generated, a reference signal RS is generated based on the transmission antenna number, and is output to the channel mapping unit 13. The channel mapping unit 13 generates first and second reference symbols as shown in FIG. 11 (not shown in the second reference symbol) and FIG.

(2) Generation of Scrambling Code SC Signal The control signal generator 12 generates a scrambling code SC calculated from information such as the length of the scrambling code SC designated from the control data or the system frequency bandwidth BW of the base station apparatus. The SCID (g) calculated from information such as the length of GSID (v) and the like is substituted into a predetermined scrambling code generation formula to generate a predetermined scrambling code and output it to the channel mapping unit 13. The channel mapping unit 13 maps the scrambling code SC as shown in FIG. 13 to each subcarrier (scrambling process). However, the scrambling process is not performed on the synchronization channel SCH signal.

  As a scrambling method for the scrambling code SC signal, scrambling processing can be performed in the frequency domain of the OFDM signal as shown in FIG. 13, but the time before the input of the S / P converter 11 shown in FIG. It can also be performed in the area (bit scrambling).

(3) Generation of Synchronization Channel SCH Signal The control signal generation unit 12 generates a synchronization channel SCH signal based on the synchronization channel SCH generation information specified from the control data. In the synchronization channel SCH generation information, the system frequency bandwidth BW of the base station apparatus, the insertion position of the synchronization channel SCH signal in the radio frame, the number of repetitions, the first synchronization channel P-SCH and / or the second synchronization channel S- Information such as the physical signal configuration of the SCH is included. The present invention is not particularly limited with respect to such information, and is a synchronization sequence index SCHID (s = 1, 2, 3,...) That is one of synchronization-related specific information included in the synchronization channel SCH (P-SCH and S-SCH). , S).

  The control signal generation unit 12 substitutes GSID (v) and cell configuration ID (w), which are indirect information of the cell ID (c) specified from the control data, in a predetermined synchronization sequence generation formula, A synchronization sequence is generated and output to the channel mapping unit 13. The channel mapping unit 13 generates a synchronization channel SCH as shown in FIG. As a method for calculating SCHID (s) from GSID (v) and cell configuration ID (w), a predefined conversion equation or conversion table can be used. The relationship between the total number (C) of cell IDs (c), the total number V of GSID (v), the total number (U) of RSID (u), and the total number (C) of cell ID (c) is expressed by Equation (2). .

That is, the total number (C) of cell IDs (c) is the product of the total number (U) of RSID (u) and the total number (V) of GSID (v). For example, as shown in FIG. 15, U = 12, V = 4, and C = 48. Furthermore, when it is set as the total number (W) of cell structure ID (w) and the total number (S) of SCHID (s) mapped by the synchronous channel SCH, each relationship is shown in Table 3.

  For example, the number of transmission antennas of the base station apparatus, the broadcast channel frequency bandwidth, the CP length of the OFDM symbol, and the radio frame timing are each in two states, and the total cell configuration ID (W) is 16 (4 bits). The system frequency bandwidth BW of the base station apparatus is 20 MHz, the total number of subcarriers is 1201, the central subcarrier is excluded, and the subcarrier interval of the reference signal RS is 6, as shown in FIG. When the mapped synchronization sequence length (for example, GCL sequence length) is 79 subcarriers (synchronization channel bandwidth 1.25 MHz), the total cell ID (C) is 840 according to Equation (3), that is, 840 cells can be identified throughout the system.

When the cell configuration ID total number (W) and the SCHID total number (S) are fixed as shown in Table 4, the cell ID total number (C) decreases as the system frequency bandwidth BW of the base station apparatus decreases.

Further, as shown in Table 5, when the cell configuration ID total number (W) and the cell ID total number (C) are fixed to 16 and 512, respectively, the required total SCHID total number (S) is the system frequency bandwidth BW of the base station apparatus. It increases with decreasing.

As shown in Table 6, when the total number of SCHID (S) and the total number of cell IDs (C) are fixed to 78 and 512, respectively, the total number of cell configuration IDs (W) increases with a decrease in the system frequency bandwidth BW of the base station apparatus. Decrease.

  In the above description, each parameter has been described using specific numerical values. However, the present invention does not limit the numerical value range that each parameter can take. For example, the number of transmission antennas of the base station apparatus, the frequency bandwidth of the broadcast channel BCH, the CP length of the OFDM symbol, and the radio frame timing are each in two states, the cell configuration ID total number (W) is 16 (4 bits), and the cell ID total number Although (C) is 512, these are not limited numerical values. Information such as the number of transmission antennas of the base station apparatus, the CP length of the OFDM symbol, and the radio frame timing can be transmitted through the broadcast channel BCH. Also, the frequency bandwidth of the broadcast channel BCH can be fixed and excluded from the total cell configuration ID (W). The total number (W) of cell configuration IDs can be adjusted by total system design. In this case, since the total number (W) of cell configuration IDs placed on the synchronization channel SCH is reduced or unnecessary (W = 0), the total number (S) of SCHIDs can be reduced, and the reception quality of the synchronization channel SCH can be improved. .

(4) Generation of Broadcast Channel BCH Signal and Shared / Dedicated Control Signal The control signal generation unit 12 extracts broadcast information such as system-specific parameters and base station apparatus / cell-specific parameters from the control data, and generates a broadcast channel BCH signal. In addition, the shared control signal required by the mobile station apparatus, the layer 1 / layer 2 control signal, the position of the RB assigned to the packet data addressed to the own station, and the AMCS parameter are extracted from the control data, and shared / individual A control signal is generated and input to the channel mapping unit 13. The channel mapping unit 13 maps the generation of the broadcast channel BCH signal and the shared / dedicated control signal to the broadcast channel BCH and the common control channel as shown in FIG.

(B) Configuration of Reception Unit of Mobile Station Device According to Embodiment 1 FIG. 3 shows a configuration of the reception unit of the mobile station device according to the present invention. As shown in Table 2, when one cell is composed of a plurality of (1 to 4) transmission antennas, a plurality (1 to 4) of mobile station apparatuses corresponding to the plurality of reception antennas shown in FIG. It can be configured by a receiving unit (branch). Here, as an example, a receiving unit (one receiving antenna branch) corresponding to one receiving antenna will be described. The receiving unit 20 of the mobile station apparatus includes a receiving antenna 21, a radio unit (RX) 22, a digital / analog signal converting unit 23, a CP deleting unit 24, a parallel / serial converting unit (P / S) 25, and a DFT converting unit (discrete). A Fourier transform (Discrete Fourier Transform) 26, a channel demapping unit 27, a parallel / serial conversion unit (P / S) 28, a control signal extraction unit 29, a channel estimation / CQI measurement unit 30, and a cell search unit 31 are included. This receiving unit constitutes an OFDM receiving apparatus.

  The downlink radio signals transmitted from the plurality of cells and the plurality of transmission antennas shown in FIG. 1 are combined at the end of the reception antenna 21 of FIG. 3 and are analogized such as filtering of the radio unit (RX) 22 and frequency conversion. / Digital signal conversion (ADC) is converted into a digital baseband signal. The CP deletion unit 24 deletes the CP part based on the OFDM symbol timing of the cell search result that is the output of the cell search unit 31 described later. The serial / parallel converter (S / P) performs serial / parallel conversion, and the DFT converter 26 performs OFDM signal demodulation. The channel demapping unit 27 demodulates the traffic channel TCH and the common control channel, the traffic channel TCH data is converted by the parallel / serial conversion unit (P / S) 28, and the packet data addressed to the own station is demodulated. The common control channel data is sent to the control signal extraction unit 29.

  On the other hand, based on the input signal from the channel demapping unit 27, the control signal extraction unit 29 is a control signal such as a synchronization channel SCH signal, a scrambling code SC signal, a reference signal RS, a broadcast channel BCH signal, and a shared / individual control signal. To extract.

(1) Extraction of Synchronization Channel SCH Signal The control signal extraction unit 29 extracts the synchronization channel SCH signal as shown in FIG. 11 from the channel demapping unit 27 and outputs it to the cell search unit 31. The cell search unit 31 detects and corrects the carrier frequency offset of the received signal, OFDM symbol timing, and detects the cell ID (c), GSID (v), and RSID (u) (described later). The cell search unit 31 outputs the detected RSID (u) to the channel estimation / CQI measurement unit 30 and the GSID (v) to the channel demapping unit 27. The OFDM symbol timing is output to the DFT converter 26 and the like. The channel demapping unit 27 generates a local scrambling code SC (g) using GSID (v), and suffers from the OFDM symbol input to the channel demapping unit 27 by descrambling processing. The scrambling code SC (g) is deleted. Note that the synchronization channel SCH signal is not scrambled on the transmission side, and therefore the synchronization channel SCH signal can be separated (extracted) directly from the received signal.

(2) Extraction of reference signal RS and channel estimation / CQI measurement The channel demapping unit 27 uses the GSID (v) from the cell search unit 31 to generate a local scrambling code SC (g), and descramble processing To do. The control signal extraction unit 29 extracts the first and second reference symbols as shown in FIG. 11 (not shown in the second reference symbol) and the channel reference mapping unit 27 and the channel reference / CQI measurement unit 30 and the cell. Output to the search unit 31. Channel estimation / CQI measurement unit 30 performs radio channel state estimation (channel estimation) using the first and second reference symbols, and outputs the result to a user data demodulation unit (not shown). On the other hand, the power of the reference signal RS of each RB is measured using the local reference signal RS, converted into a signal format defined in advance by the system, and fed back to the base station apparatus through the uplink. When the GCL sequence is used for the first and second reference symbols, for example, a local reference signal is generated by RSID (u), correlation processing is performed with the extracted reference signal RS, and IDFT conversion (frequency domain signal is converted to time domain). Channel estimation can be performed by a series of filtering processing (removal of interference components and noise components) and DFT transform (time domain signal is converted to frequency domain).

(3) Extraction of Broadcast Channel BCH Signal and Shared / Dedicated Control Signal The control signal extraction unit 29 extracts the broadcast channel BCH signal shown in FIG. 11, and broadcasts system-specific parameters and base station apparatus / cell-specific parameters. Demodulate information. The individual control information such as the shared control signal required by the mobile station apparatus, the layer 1 / layer 2 control signal, the position of the RB assigned to the packet data addressed to the own station, and the AMCS parameter is extracted from the first OFDM symbol of each RB. The individual control signal is demodulated and output to a user data demodulator (not shown).

(4) Cell Search Procedure The cell search unit 31 receives a plurality of reference signals RS and a multiplexed signal of the synchronization channel SCH sent from a plurality of cells and a plurality of transmission antennas. The cell search unit 31 receives carrier frequency offset synchronization, OFDM symbol timing synchronization, radio frame timing synchronization, cell ID (c), RSID (u), GSID (v), cell configuration ID (w), and each reference signal RS reception. The power is detected and output as a cell search result. The RSID (u) is output to the channel estimation unit 30 to generate a local reference signal RS, and perform channel estimation and CQI calculation. GSID (v) is output to the channel demapping unit, and descramble processing of the scrambling code is performed.

  FIG. 4 is a block diagram showing a configuration of the cell search unit 31. The time / frequency synchronization unit 31a, the SCHID (u) identification unit 31b, the phase difference processing unit 31c, the IDFT conversion unit 31d, the power calculation unit 31e, the maximum value detection unit 31f, and the multiplication unit 31g are included. The phase difference processing unit 31c, the IDFT conversion unit 31d, the power calculation unit 31e, and the maximum value detection unit 31f constitute a reference signal processing unit 31h.

  The time / frequency synchronization unit 31a detects the carrier frequency offset and the OFDM symbol timing. The SCHID identifying unit 31b identifies SCHID (s) mapped to the synchronization channel SCH having the maximum reception power from the synchronization channel SCH multiplexed signals of a plurality of cells and a plurality of transmission antennas. In the case of the GCL sequence, for example, the SCHID (s) can be identified by the IDFT method (described later) as in the reference sequence. A multiplexed signal of the reference signal RS from which the scrambling code (g) component corresponding to GSID (v) is removed from the channel demapping unit 27 (descrambled) (multiplexed signal of a plurality of GCL sequences) is a phase difference processing unit 31c. The RSID (u) having the maximum power value is identified using the IDFT method in which the maximum power is detected by the IDFT conversion unit 31d, the power value calculation unit 31e, and the maximum power detection unit 31f.

  FIG. 5 is a flowchart showing the operation of the cell search unit 31 configured as described above. Here, a cell search procedure for the synchronization channel SCH signal of the present invention in which GSID (v) and cell configuration ID (w) are inserted is shown. In step 1 (S1, first stage), the carrier frequency offset and the OFDM symbol timing are detected by the time / frequency synchronization unit 31a shown in FIG. 4, and a conventional method (for example, Non-Patent Document 10, Non-Patent Document 11) is performed. The description is omitted here.

  In Steps 2 and 3 (S2, S3, second stage), the SCHID (s) identification unit 31b shown in FIG. 4 determines the maximum from the synchronization channel SCH multiplexed signals of a plurality of base station apparatuses, a plurality of cells and a plurality of transmission antennas. SCHID (s) mapped to the synchronization channel SCH having received power is identified. The type of synchronization sequence (for example, GCL sequence, orthogonal code, etc.), the mapping method for each subcarrier of the synchronization sequence (for example, continuous mapping between subcarriers or intermittent insertion by inserting null subcarriers, or the second. Mapping to be divided into one synchronization channel P-SCH and second synchronization channel S-SCH), and a synchronization sequence identification / detection method (for example, first synchronization channel P-SCH and second synchronization channel S-SCH) Detection method of cross-correlation of synchronization channel SCH having a hierarchical structure of the above, or an autocorrelation detection method of synchronization channel SCH having a non-hierarchical structure of only the second synchronization channel S-SCH, or hybrid detection that is a combination of the two Method) is omitted because the conventional method can be applied. For example, in the case of a GCL sequence, the IDCL method can be used to detect the GCL sequence index GCLID having the maximum power, that is, SCHID (s).

Table 7 shows an example in which the cell configuration ID (w) and GSID (v) are calculated from the SCHID (s) mapped to the synchronization channel SCH having the maximum received power identified. For example, when SCHID is No. 12 (s = 12), it means that two base station apparatus transmission antennas and GSID are No. 4 (v = 4).

  In steps 4 and 5 (S4, S5, third stage), RSID (mapped to reference signal RS having the maximum received power) from multiple signals of reference signals RS of a plurality of base station apparatuses, a plurality of cells and a plurality of transmitting antennas. u) is identified. As shown in FIG. 15, the reference signal sequence of a cell belonging to one GSID (v) corresponding to SCID (g) is mapped with a GCL sequence having a different GCLID as in Expression (1). Therefore, the GCLID identification method shown in FIG. 4 can be used.

  The reference signal RS multiplexed signal (descrambled by the second stage GSID (v)) sent from the control signal extraction unit 29 is a conventional method (see Non-Patent Document 12), and the phase difference processing unit 31c The RSID (u) having the maximum power value is identified using the IDFT method in which the maximum power is detected by the IDFT conversion unit 31d, the power value calculation unit 31e, and the maximum power detection unit 31f.

  And according to Formula (2), cell ID (c) is computable by multiplication of identified GSID (v) and RSID (u).

  In the present invention, the reference signal RS has been described as a GCL sequence, but is not limited and may be another sequence such as an orthogonal code. As an identification method, a cross-correlation method using a local reference sequence may be used. Further, various reference sequence generation methods may be used as shown in FIG. Further, the correspondence relationship between the number of base station apparatus transmission antennas and the reference signal RS, and the correspondence relation with the reference sequence are not limited, and the multiplexing of the reference signal RS between the transmission antennas, between the cells, and between the base station apparatuses is performed. Code division multiplexing (CDM), FDM, TDM, and combinations thereof may be used. Other reference sequences suitable for channel estimation and cell identification may be used. Further, although one base station apparatus has been described as having three cells, a plurality of cells such as six cells may be used.

  In the present invention, the arrangement relationship of GSID (v), SCID (g), and RSID (u) as shown in FIG. 15 is shown, but the same SCID (g) is assigned between base station apparatuses belonging to the same GSID (v). Therefore, the scrambling code SC cannot serve to whiten the interference signal from the adjacent base station apparatus. As shown in FIG. 18, in order to reduce interference between base station apparatuses, GSID (v) can be maintained, and different SCIDs (g) can be arranged between adjacent cells.

  Also, as shown in FIG. 19, GSID (v), SCID (g), and RSID (u) can be arranged by other methods. FIG. 19 is the same as FIG. 15. For example, reference is assigned to one GSID (v) for four base station apparatuses and different RSID (u) for four base station apparatuses belonging to one GSID (v). A sequence is allocated, that is, a common reference sequence is allocated to three cells 1, 2, and 3 belonging to one base station apparatus, and phase rotation PR (Phase Rotations) in the frequency domain is performed with respect to the common reference sequence between cells. For example, a common reference sequence having phase rotation such as phase rotation angles φ1 = 0, φ2 = 2p / 3, φ3 = 4p / 3 is used for cells 1, 2, and 3.

  As shown in FIG. 19, for each cell, the RSID (u), GSID (v), SCID (g), and the arrangement (mapping) of phase rotation PR between cells have good channel estimation and cell identification characteristics. The cell ID (c) can be identified at the same time as it is obtained. In FIG. 19, different SCIDs (g) can be arranged between adjacent cells in consideration of inter-cell interference as shown in FIG. Further, the maximum system frequency bandwidth BW specific to the base station and the frequency bandwidth of the mobile station apparatus are not in the above specific frequency values but in other units such as the number of radio resource blocks BR or the number of subcarriers. It may be defined.

(Embodiment 2)
Embodiment 2 of the present invention proposes a configuration of a synchronization channel SCH and a cell search procedure applied to base station apparatuses having different system frequency bandwidths (for example, 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, and 20 MHz). The cell search procedure for identifying the cell ID (c) by identifying the configuration of the synchronization channel SCH including GSID (v) and the identification of GSID (v) and RSID (u) is proposed in the first embodiment. However, as shown in Tables 4, 5, and 6, when the cell configuration ID total number (W) and the SCHID total number (S) are fixed, the cell ID total number (C) is equal to the system frequency bandwidth BW of the base station apparatus. Decreases with decreasing.

  When the cell configuration ID total number (W) and the cell ID total number (C) are fixed, the required total SCHID total number (S) increases as the system frequency bandwidth BW of the base station apparatus decreases. Furthermore, when the SCHID total number (S) and the cell ID total number (C) are fixed, the cell configuration ID total number (W) decreases as the system frequency bandwidth BW of the base station apparatus decreases. In the EUTRA system, a configuration of a synchronization channel SCH suitable for base station apparatuses having different system frequency bandwidths (for example, 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, 20 MHz) is desirable.

(A) Configuration of Transmission Unit of Base Station Apparatus According to Embodiment 2 The configuration of the base station apparatus transmission unit according to the present invention is similar to that of Embodiment 1. Only different parts will be described with reference to FIG.

(1) Generation of Synchronization Channel SCH Signal Table 8 shows that the synchronization sequence length (for example, GCL sequence length) mapped to the synchronization channel SCH is 79 subcarriers (synchronization channel bandwidth 1) as shown in FIG. .25 MHz) is an example of the required synchronization channel SCH signal calculation for different system frequency bandwidths. FIG. 20 shows a synchronization channel SCH configuration using a plurality of synchronization channel SCH signals, for example, the first synchronization channel SCH1 and / or the second synchronization channel SCH2, in accordance with different system frequency bandwidth base station apparatuses as shown in FIG.

  When the system frequency bandwidth is 1.25 MHz, 2.5 MHz, 5 MHz, or 10 MHz (hereinafter referred to as “first band group”), the first synchronization channel SCH1 and / or the second synchronization channel SCH2 is a synchronization channel. Configure the SCH. When the system frequency bandwidth is 20 MHz (hereinafter referred to as “second band group”), the first synchronization channel SCH1 alone constitutes the synchronization channel SCH. As shown in Table 8, the SCHID total number (S1) of the first synchronization channel SCH1 represents the cell configuration ID total number (W = 16), and the rest represents the first RSID total number (V1 = 4).

  In the case of the first band group, the second synchronization channel SCH2 is added, and the total number of SCHIDs (S2) of the second synchronization channel SCH2 represents the second total number of RSIDs (V2). The combination of the first RSID total number (V1) and the second RSID total number (V2) represents the RSID total number (V = V1 · V2). In the case of the first band group, the synchronization channel SCH is configured by the first synchronization channel SCH1 and the second synchronization channel SCH2 as shown in FIG. In the case of the second band group, the synchronization channel SCH is configured only by the first synchronization channel SCH1 as shown in FIG.

  As shown in Table 5, the required total number of SCHIDs (S) increases as the system frequency bandwidth decreases. In the first embodiment, it is assumed that the number of transmission antennas of the base station apparatus, the broadcast channel BCH frequency bandwidth, the CP length of the OFDM symbol, and the radio frame timing are each in two states, and the total number of cell configuration IDs (W) is 16. The index relationship was shown. In the conventional method (see Non-Patent Document 13), when the system frequency bandwidth is 1.25 MHz, 2.5 MHz, and 5 MHz, the frequency bandwidth of the broadcast channel BCH is 1.25 MHz, and the system frequency bandwidth is 10 MHz and 20 MHz. In this case, there is a proposal that the frequency bandwidth of the broadcast channel BCH is 5 MHz.

Since the system frequency bandwidth is 10 MHz, the synchronization channel SCH can be configured with only the first synchronization channel SCH1 as in the case of the system frequency bandwidth of 20 MHz. In addition, two states of the frequency bandwidth of the broadcast channel BCH, which is cell specific information, can correspond to the first and second band groups. Furthermore, as shown in FIG. 7.1.2.4.3-2 of Non-Patent Document 3, with respect to the proposal that the frequency bandwidth of the broadcast channel BCH is 1.25 MHz for all system frequency bandwidths. Thus, two states of the frequency bandwidth of the broadcast channel BCH can be used for the identifiers of the first and second band groups. The combination of the first band group using two synchronization channel SCH signals and the second band group using one synchronization channel SCH signal can be adjusted by changing the total SCHID (S).

Table 9 shows that the first and second synchronization channels SCH1 and SCH2 use the synchronization channel SCH configuration of FIG. 6, or the first and second synchronization channels SCH1 and SCH2 have the synchronization channel SCH configuration of FIG. When used (the first synchronization channel P-SCH is common to base station apparatuses and the second synchronization channel S-SCH is mapped to the synchronization channel SCH sequence), the synchronization sequence length mapped to the synchronization channel SCH ( For example, when the GCL sequence length) is 37 subcarriers (synchronization channel bandwidth 1.25 MHz), this is an example of required synchronization channel SCH calculation for different system frequency bandwidths. A synchronization channel SCH configuration using a plurality of synchronization channels SCH is shown to be adapted to base station apparatuses having different system frequency bandwidths.

  Further, the first and second synchronization channels SCH1 and SCH2 may be a combination of FIG. 2, FIG. 6, FIG. 7, FIG.

  The control signal generator 12 generates a synchronization channel SCH1 and / or SCH2 signal based on the synchronization channel SCH1 and / or SCH2 generation information specified from the control data. The synchronization channel SCH1 and / or SCH2 generation information includes the system frequency bandwidth BW of the base station apparatus, the insertion position of the synchronization channel SCH1 and 2 signals in the radio frame, the number of repetitions, the first synchronization channel P-SCH and / or the first Information such as physical signal configurations of the two synchronization channels S-SCH is included. The present invention is not particularly limited with respect to such information, and the first SCHID (s1) and / or the first SCHID (s1) which is one or two of the synchronization-related specific information included in the synchronization channel SCH (P-SCH and S-SCH). 2 SCHID (s2).

  The control signal generation unit 12 includes a first GSID (v1) and / or a second GSID (v2) that is indirect information of the cell ID (c) specified from the control data, and a cell configuration ID ( Substituting w) into the synchronization sequence generation formula, a predetermined synchronization sequence is generated and output to the channel mapping unit 13. The channel mapping unit 13 generates synchronization channels SCH1 and SCH2 as shown in FIG. The first and second SCHIDs (s1, s2) are calculated from the first and second GSIDs (v1, v2) and the cell configuration ID (w) as a calculation method using a predefined conversion formula or conversion table. be able to.

(B) Configuration of Receiving Unit of Mobile Station Device According to Embodiment 2 The configuration of the mobile station device receiving unit according to the present invention is similar to that of the first embodiment. Only different parts will be described with reference to FIG.

(1) Extraction of Synchronization Channel SCH Signal The control signal extraction unit 29 extracts the synchronization channel SCH1 and / or SCH2 signals as shown in FIG. 20 from the channel demapping unit 27 and outputs them to the cell search unit 31. First, the first GSID (v1) and the cell configuration ID (w) included in the synchronization channel SCH1 are identified by the SCHID (s) identification unit 31b illustrated in FIG. The state of the frequency bandwidth (or the first and second band groups) of the broadcast channel BCH is determined from the cell configuration ID (w), and the presence / absence of the subsequent second synchronization channel SCH2 is determined. When there is the second synchronization channel symbol SCH2, the second GSID (v2) is identified for the extracted data signal (partial signal of the second synchronization channel SCH2), and GSID (v) is calculated.

  In the present invention, the control signal extraction unit 29 extracts (duplicates) the data signal corresponding to the synchronization channel SCH1 and / or SCH2 signal in advance, extracts the synchronization channel SCH1 signal first, and then extracts the subsequent second synchronization channel SCH2 If it is determined that there is, a control signal may be output to the control signal extraction unit 29 to extract the second synchronization channel SCH2.

(2) Cell search procedure FIG. 9 considers the first and second first synchronization channels SCH1 and SCH2, and GSID (v), which is indirect information of the cell ID (c), the number of transmission antennas of the base station apparatus, The cell search procedure for the synchronization channel SCH signal of the present invention in which the cell configuration ID (w) such as broadcast channel BCH frequency bandwidth (or first and second band groups) information is inserted is shown.

  Step 1 (T1, first stage) is the same as that of the first embodiment, and thus the description thereof is omitted. Steps 2, 3, 4, 5 (T2, 3, 4, 5) represent the second stage. In step 2 (T2), the SCHID (s) identifying unit 31b shown in FIG. 4 uses the first synchronization channel SCH1 having the maximum received power from the first synchronization channel SCH1 multiplexed signal of a plurality of cells and a plurality of transmission antennas. SCHID (s1) mapped to is identified. Since the type and identification / detection method of the first synchronization sequence are the same as those in the first embodiment, description thereof is omitted. A cell configuration ID (w) and a first GSID (v1) are calculated from the identified SCHID (s1).

  In step 3 (T3), the SCHID (s) identifying unit 31b shown in FIG. 4 calculates the frequency bandwidth (or the first and second band groups) of the broadcast channel BCH from the cell configuration ID (w) calculated. The state is determined, and the presence / absence of the subsequent second synchronization channel SCH2 is determined. When there is no second synchronization channel symbol SCH2, cell ID (c) is finally obtained by multiplying the first GSID (v1) and RSID (u) by Steps 6 and 7 (T6 and 7) as in the first embodiment. ) Can be calculated.

  When it is determined in step 3 (T3) that there is a subsequent second synchronization channel SCH2, the SCHID (s2) mapped to the second synchronization channel SCH2 in step 4 (T4) is identified. Since the type and identification / detection method of the second synchronization sequence are the same as those in the first embodiment, description thereof is omitted. The second GSID (v2) is calculated from the identified SCHID (s2), and the cell ID (c) can be calculated by multiplication with RSID (u) in steps 6 and 7 (T6, 7).

  In the present invention, a method for determining the state of the frequency bandwidth (or the first and second band groups) of the broadcast channel BCH from the cell configuration ID (w) has been presented. According to the structural design, it is possible to make a determination in step 1 (first stage), that is, in the stage of frequency / time synchronization.

(Embodiment 3)
In Embodiment 3 of the present invention, the configuration of a synchronization channel SCH applied to a base station apparatus having a 20 MHz system frequency bandwidth for mobile station apparatuses of mobile station classes having different frequency bandwidths (for example, 10 MHz and 20 MHz). And a cell search procedure is proposed.

In the first and second embodiments, as shown in Table 1, the reference sequence length (N _d ) is mapped in accordance with the entire system frequency bandwidth. When the downlink signal of the 20 MHz base station apparatus is received by the 10 MHz mobile station apparatus, only a part of the reference sequence can be received. This leads to deterioration in the detection characteristics of RSID (u). A method of specifying a frequency band position (center frequency shift) to be used by a mobile station apparatus using a 10 MHz bandwidth is shown for a base station apparatus using a 20 MHz bandwidth (see Non-Patent Document 3). reference). This will be described with reference to FIG. The mobile station apparatus first performs a cell search (initial cell search, standby cell search, communication cell search) using the synchronization channel SCH and the reference signal RS.

  Specifically, when the power is turned on, the mobile station device first performs a band search at intervals of W-CDMA channel number UARFCN (frequency raster: 200 KHz), and detects a valid cell signal at the center of 1.25 MHz of the 20 MHz bandwidth. If it has been done, an initial cell search is performed using the synchronization channel SCH and the reference signal RS. After the cell search is completed, the broadcast channel BCH is received. The broadcast channel BCH includes frequency band information (frequency shift information) to be used by each mobile station apparatus. Waiting at the center of 1.25 MHz of 20 MHz bandwidth. When shifting from the standby mode to the active mode, the mobile station apparatus moves to the use frequency band position (center carrier frequency shift) according to the control information, and starts packet data transfer. Three cases of 10 MHz bandwidth can be considered with respect to the 10 MHz mobile station apparatus, symmetrically with respect to the base station center frequency fc, or on the left and right sides of fc.

(A) Configuration of Transmission Unit of Base Station Apparatus According to Embodiment 3 The configuration of the base station apparatus transmission unit according to the present invention is similar to that of Embodiments 1 and 2. Only different parts will be described with reference to FIG.

(1) Generation of Reference Signal RS When the system frequency bandwidth BW of the base station apparatus is 10 MHz or less, the control signal generation unit 12 is the same as in Embodiments 1 and 2, and FIG. 11 (the second reference symbol is not shown) First and second reference symbols as shown in FIG. 14 are generated. When the system frequency bandwidth BW is 20 MHz, reference symbols are generated by the first and second reference signals RS1 and RS2 as shown in FIG. The same GCL sequence length (N _G = 101) is mapped to the first and second reference signals RS1 and RS2. In each table in the first and second embodiments, the column of 20 MHz base station device can be rewritten in the column of 10 MHz base station device.

(B) Configuration of Receiving Unit of Mobile Station Device According to Embodiment 3 The configuration of the mobile station device receiving unit according to the present invention is similar to that of the first embodiment. Only different parts will be described with reference to FIG.

(1) Extraction of Reference Signal RS The control signal extraction unit 29 extracts the first and second reference symbols as shown in FIG. 11 (not shown in the second reference symbol) and FIG. Output to estimation / CQI measurement unit 30 and cell search unit 31.

  In the channel estimation / CQI measurement unit 30, when the system frequency bandwidth BW of the base station apparatus is 20 MHz, the radio propagation path state is estimated using the first and second reference symbols included in the first and second reference signals RS1 and RS2. (Channel estimation) is performed and output to a user data demodulator (not shown). On the other hand, the power of the reference signal RS of each RB is measured using the local first and second reference signals RS1 and 2, converted into a signal format defined in advance by the system, and fed back to the base station apparatus through the uplink. .

(2) Cell Search Procedure When a mobile station apparatus performs an initial cell search, a standby cell search, and a busy cell search, the mobile station apparatus may use a 10 MHz synchronization channel SCH and a reference signal RS that are symmetrical with respect to the base station center frequency fc. it can. As shown in the second embodiment, the initial cell search, standby cell search, and call cell search procedures identify two states of the frequency bandwidth of the broadcast channel BCH, or first and second band groups, and a 20 MHz system. When it is determined that the base station apparatus has a frequency bandwidth, the received reference signal RS can be identified left and right symmetrically with respect to the base station center frequency fc, and then RSID (u) can be identified. Further, it is not necessary to identify the two states of the frequency bandwidth of the broadcast channel BCH or the first and second band groups. The first and second synchronization channels SCH1 and SCH2 can also be used.

  The cell search procedure can basically use the first and second embodiments. However, when it is determined that the cell search procedure is a 20 MHz base station apparatus and a 10 MHz mobile station apparatus, the received reference signal RS is used as the base station center frequency. RSID (u) is identified after the left and right are exchanged symmetrically with respect to fc. When it is determined that the mobile station apparatus is a 20 MHz base station apparatus and a 20 MHz mobile station apparatus, and the first and second reference signals RS1 and 2 are equal, RSID (u) is obtained by averaging the first and second reference signals RS1 and RS2. Cell search characteristics can be improved.

  Configuration of the transmission unit 10 of the base station device and the reception unit 20 of the mobile station class of mobile station class having different frequency bandwidths for the system frequency bandwidth BW of different base station devices as in the above embodiments That is, the hardware configuration such as the sampling frequency, the filter bandwidth, the memory capacity, and the software configuration including the various parameters are different. Base station equipment and mobile station equipment can be realized by switching hardware and software using a common hardware and software platform, or fixed at different frequencies using specific hardware and software can do. Alternatively, it can be adaptively changed according to various conditions such as time and place. The present invention can also be applied to base station apparatuses and mobile station apparatuses having such various configuration methods.

It is a block diagram which shows the structure of the transmission part of a base station apparatus. It is a figure which shows the synchronization sequence length mapped by the synchronization channel. It is a block diagram which shows the structure of the receiving part of a mobile station apparatus. It is a block diagram which shows the structure of a cell search part. It is a flowchart which shows operation | movement of a cell search part. It is a figure which shows the structure of a synchronous channel. It is a figure which shows the structure of a synchronous channel. It is a figure which shows the structure of a synchronous channel. It is a flowchart which shows operation | movement of a cell search part. It is a figure which shows the downlink radio frame structure of EUTRA assumed based on the proposal of 3GPP. It is a figure which shows the example of a mapping of the synchronization channel SCH. It is a figure which shows the example of mapping of reference signal RS in one RB of the downlink radio frame structure of EUTRA. An example of scrambling code SC mapping is shown. The example of a reference signal sequence mapping in case a base station apparatus has multiple transmission antennas (1-4) is shown. An example of a method of expressing a cell ID (c) by a combination of GSID (v) and RSID (u) is shown. An example of a cell search procedure in an EUTRA / EUTRAN system is shown. It is a figure which shows a mode that cell ID (c) is identified using reference signal RS using the scrambling group SG concept used for W-CDMA system. It is a figure which shows the example which has arrange | positioned different SCID (g) between adjacent base stations in consideration of interference between base station apparatuses. It is a figure which shows the example of arrangement | positioning of another reference sequence. FIG. 6 is a diagram illustrating a synchronization channel SCH configuration using a plurality of synchronization channel SCH signals, for example, a first synchronization channel SCH1 and / or a second synchronization channel SCH2, adapted to different system frequency bandwidth base station apparatuses. It is a figure which shows the method of the frequency band position designation (center frequency shift) which should be used of the mobile station apparatus which uses a 10-MHz bandwidth with respect to the base station apparatus which uses a 20-MHz system frequency bandwidth.

Explanation of symbols

10 Base station equipment (transmitter)
11 S / P conversion unit 12 Control signal generation unit 13 Channel mapping unit 14 IDFT unit 15 P / S conversion unit 16 CP insertion unit 17 DAC processing unit 18 Radio unit (TX)
19 Transmitting antenna 20 Mobile station device (receiving unit)
21 receiving antenna 22 radio unit (RX)
23 ADC processing unit 24 CP deletion unit 25 S / P conversion unit 26 DFT conversion unit 27 Channel de-mapping unit 28 P / S conversion unit 29 Control signal extraction unit 30 Channel estimation / CQI measurement unit 31 Cell search unit 31a Time / frequency Synchronization unit 31b Synchronization sequence index SCHID identification unit 31c Phase difference processing unit

Claims (9)

An OFDM transmission apparatus that transmits a radio signal using OFDM,
A control signal generator for generating a synchronization channel signal including at least a reference signal used for channel estimation, a scrambling code signal, and a group scrambling index and / or a cell-specific information index;
An OFDM transmission apparatus comprising: a channel mapping unit that maps the reference signal and the synchronization channel signal to a predetermined subcarrier and multiplies the scrambling code by an OFDM signal.   The OFDM transmission apparatus according to claim 1, wherein the control signal generation unit generates a plurality of different synchronization channel signals including cell specific information indexes indicating different system frequency bandwidths. An OFDM receiver that receives a radio signal transmitted by OFDM,
A control signal extraction unit that extracts a synchronization channel signal including at least a reference signal used for channel estimation, a scrambling code signal, and a group scrambling index and / or a cell specific information index from the received signal;
An OFDM receiver comprising: a cell search unit that calculates a cell physical layer index based on a reference sequence index of the extracted reference signal and a group scrambling index of the extracted synchronization channel signal. . The cell search unit
A time / frequency synchronization unit for detecting carrier frequency offset and OFDM symbol timing;
A synchronization sequence index identifying unit that identifies a synchronization sequence index mapped to a synchronization channel having the maximum received power from a plurality of synchronization channel signals, and outputs a group scrambling index and / or a cell-specific information index;
Based on the reference signal, a reference signal processing unit that outputs received power information of the reference signal and a reference sequence index;
4. The OFDM receiving apparatus according to claim 3, further comprising: a multiplication unit that multiplies the reference sequence index and a group scrambling index of the extracted synchronization channel signal to calculate a cell physical layer index. The control signal extraction unit extracts a plurality of different synchronization channel signals including cell specific information indexes indicating different system frequency bandwidths;
The synchronization sequence index identification unit identifies a first group scrambling index and a cell specific information index included in the first synchronization channel signal, and based on the cell specific information index, 5. The OFDM receiving apparatus according to claim 4, wherein presence / absence is determined, and if there is a subsequent synchronization channel signal, a group scrambling index and a cell specific information index are further identified for the subsequent synchronization channel signal.   A base station apparatus comprising the OFDM transmission apparatus according to claim 1.   A mobile station apparatus comprising the OFDM receiver according to any one of claims 3 to 5.   An OFDM communication system comprising the base station apparatus according to claim 6 and the mobile station apparatus according to claim 7. On the transmission side of a wireless communication system that transmits and receives wireless signals using OFDM,
A synchronization channel signal including at least a reference signal used for channel estimation, a scrambling code signal, a group scrambling index and / or a cell specific information index is generated, and the reference signal and the synchronization channel signal are mapped to a predetermined subcarrier. And a cell search method for transmitting the scrambling code multiplied by an OFDM signal,
On the receiving side, at least a reference signal used for propagation path estimation, a scrambling code signal, and a synchronization channel signal including a group scrambling index and / or a cell specific information index are extracted from the received signal,
A cell search method comprising calculating a cell physical layer index based on a reference sequence index of the extracted reference signal and a group scrambling index of the extracted synchronization channel signal.