JP2015097359A - Td-lte radio base station and synchronization method thereof - Google Patents

Td-lte radio base station and synchronization method thereof Download PDF

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JP2015097359A
JP2015097359A JP2013237420A JP2013237420A JP2015097359A JP 2015097359 A JP2015097359 A JP 2015097359A JP 2013237420 A JP2013237420 A JP 2013237420A JP 2013237420 A JP2013237420 A JP 2013237420A JP 2015097359 A JP2015097359 A JP 2015097359A
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base station
radio base
synchronization
lte radio
synchronization signal
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智哉 内池
Tomoya Uchiike
智哉 内池
賢一 野川
Kenichi Nogawa
賢一 野川
裕丈 石井
Hirotake Ishii
裕丈 石井
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Hitachi Ltd
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Abstract

PROBLEM TO BE SOLVED: To maintain synchronization between base stations without influencing communication with a terminal.SOLUTION: A TD-LTE radio base station performs synchronization between base stations by receiving a first downlink synchronization signal from a donor base station, which is another synchronized TD-LTE radio base station. The TD-LTE radio base station comprises: a synchronization detection unit that detects a first downlink synchronization signal received from the donor base station, and outputs synchronization detection timing information; and a control unit that detects synchronization timing difference with the donor base station referring to the synchronization detection timing information after establishing synchronization with the donor base station, and stops transmitting part of a second downlink synchronization signal transmitted by the TD-LTE radio base station in order to refer to the first downlink synchronization signal from the donor base station when correction of the synchronization timing difference is necessary.

Description

本発明は無線基地局に係り、特にTD-LTE無線システムに対応した無線基地局間の同期方法に関する。   The present invention relates to a radio base station, and more particularly to a synchronization method between radio base stations corresponding to a TD-LTE radio system.

無線基地局の同期をとる方法には、大別して、(1)衛星測位システム(GPS: Global Positioning System)の受信機を無線基地局に備え、GPS信号に同期させる方法、(2)ＩＰ等のパケットプロトコルネットワークに同期させる方法、および(3)他の隣接する同期化された無線基地局（以下、Donor基地局と呼ぶ。）に対し従属同期させる方法が、一般的に広く知られている。いずれの方法にも長短があり、GPS衛星を捕捉し難い地理的条件であったり、無線基地局が収容されるネットワーク条件によって同期精度が得にくい条件であったりするので、制約条件（システム構築条件）に応じた使い分けがなされる。(3)の無線基地局間で同期をとる方法は、このような制約条件が発生するときや、無線基地局間の同期のために特別な受信系回路を必要としないTDD(Time Division Duplex)方式の無線基地局では、有効な同期方法のひとつである。   Methods for synchronizing radio base stations can be broadly classified as follows: (1) A satellite positioning system (GPS: Global Positioning System) receiver equipped in a radio base station and synchronized with GPS signals, (2) IP, etc. A method of synchronizing with a packet protocol network and (3) a method of subordinate synchronization with other adjacent synchronized radio base stations (hereinafter referred to as Donor base stations) are generally well known. Each method has its pros and cons, and it is difficult to acquire GPS satellites, or it is difficult to obtain synchronization accuracy depending on the network conditions in which wireless base stations are accommodated. ) Is used properly according to. The method of synchronizing between radio base stations in (3) is TDD (Time Division Duplex) that does not require a special receiving system circuit when such constraints occur or for synchronization between radio base stations This is one of the effective synchronization methods in the system radio base station.

TDD方式の無線基地局間の同期に関しては、Donor基地局に対する初期同期捕捉後の同期維持方法が課題となる。無線基地局が有するクロック生成部の精度に応じて一定時間経過毎に同期を維持する必要があるが、TDD方式の無線基地局間の同期維持では、自無線基地局配下で通信中の移動端末に対する送信タイミングにおいて、何らかの方法にてDonor基地局からのリファレンス同期信号を参照し、それに同期状態を維持させなければならない。特に、TD-LTE無線システムでは、隣接する他の無線基地局との干渉影響の観点から、3GPP(Third Generation Partnership Project)にてタイミング同期精度(3us以内)の規定がなされており高い同期維持精度が求められる。   As for synchronization between TDD-type radio base stations, a method of maintaining synchronization after initial synchronization acquisition for the Donor base station becomes an issue. Although it is necessary to maintain synchronization at every elapse of a certain time according to the accuracy of the clock generation unit possessed by the radio base station, in maintaining synchronization between radio base stations of the TDD scheme, the mobile terminal communicating under its own radio base station The reference synchronization signal from the Donor base station must be referred to by some method at the transmission timing for the, and the synchronization state must be maintained. In particular, in the TD-LTE wireless system, timing synchronization accuracy (within 3us) is defined by 3GPP (Third Generation Partnership Project) from the viewpoint of interference effects with other adjacent radio base stations, and high synchronization maintenance accuracy Is required.

特許文献１によれば、TDD無線基地局間の同期方法として、無線基地局装置が、基地局間同期モードと通常通信モードの２モードを持つことにより、「端末との通信時に基地局間同期をとろうとすることに伴って発生する不具合を防止する」としている。すなわち、所定時間毎に、通常通信モードと基地局間同期モードとを切り替え、基地局間同期モードでDonor基地局からの同期信号に対してスライディング相関をとることによって、同期ずれ量を検出および補正する。その基地局間同期モードの間、無線基地局装置は端末へスリープモードを通知することで、端末側には異常状態であると認識させることなく、また、端末の消費電力を節約することができる。   According to Patent Document 1, as a synchronization method between TDD radio base stations, a radio base station apparatus has two modes of an inter-base station synchronization mode and a normal communication mode. To prevent problems caused by trying to take care of it. " In other words, the synchronization deviation amount is detected and corrected by switching between the normal communication mode and the inter-base station synchronization mode at every predetermined time and taking a sliding correlation with the synchronization signal from the Donor base station in the inter-base station synchronization mode. To do. During the inter-base station synchronization mode, the radio base station apparatus notifies the terminal of the sleep mode, so that the terminal side does not recognize that it is in an abnormal state, and the power consumption of the terminal can be saved. .

特開２００９−２１２５９４号公報JP 2009-212594 A

特許文献１によれば、端末側は不意に通信断に陥ったことにはならず、またスリープモードであるが故にその間の電力消費を低減できるメリットはあるが、Donor基地局との同期維持動作の際に、自無線基地局の配下で通信している端末に対し、意図的に無線基地局側よりスリープモードを通知するため、たとえ微小時間であっても端末の通信断は余儀なくされ、運用・サービスの継続という点で課題がある。   According to Patent Document 1, the terminal side does not unexpectedly lose communication, and since it is in the sleep mode, there is a merit that power consumption can be reduced, but the operation of maintaining synchronization with the Donor base station In this case, since the wireless base station side intentionally notifies the terminal communicating with its own wireless base station of the sleep mode, the communication of the terminal is forced to be interrupted even in a minute time.・ There is a problem in terms of service continuity.

開示するTD-LTE無線基地局は、同期化された他のTD-LTE無線基地局であるDonor基地局からの第１の下り同期信号を受信して基地局間同期を行うTD-LTE無線基地局である。TD-LTE無線基地局は、Donor基地局から受信した第１の下り同期信号を検波し、同期検波タイミング情報を出力する同期検波部、およびDonor基地局との同期確立後に、同期検波タイミング情報を参照して、Donor基地局との同期タイミング差分を検出し、同期タイミング差分の補正が必要なときに、Donor基地局からの第１の下り同期信号を参照するために、該TD-LTE無線基地局が送信する第２の下り同期信号の一部を送信停止する制御部を備える。   The disclosed TD-LTE radio base station receives a first downlink synchronization signal from a Donor base station that is another synchronized TD-LTE radio base station, and performs inter-base station synchronization. Station. The TD-LTE radio base station detects the first downlink synchronization signal received from the Donor base station, outputs the synchronous detection timing information, and after establishing synchronization with the Donor base station, provides the synchronous detection timing information. Referring to the TD-LTE radio base in order to detect the synchronization timing difference with the Donor base station and refer to the first downlink synchronization signal from the Donor base station when the synchronization timing difference needs to be corrected. A control unit that stops transmission of a part of the second downlink synchronization signal transmitted by the station is provided.

本発明によれば、端末との通信への影響を発生させることなく、基地局間の同期を維持することが可能となる。   ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to maintain the synchronization between base stations, without producing the influence on communication with a terminal.

無線システムの概要図である。1 is a schematic diagram of a wireless system. 無線基地局３００の構成である。This is a configuration of the radio base station 300. ＢＢ信号処理部３０５の構成図である。3 is a configuration diagram of a BB signal processing unit 305. FIG. Donor基地局からの下り同期信号の例である。It is an example of the downlink synchronous signal from a Donor base station. 無線基地局の状態遷移を示すシーケンス図である。It is a sequence diagram which shows the state transition of a wireless base station. 同期維持の制御手順を示すフローチャートである。It is a flowchart which shows the control procedure of a synchronization maintenance. 同期維持中の無線基地局の下り送信信号および制御信号のタイミングチャートである。It is a timing chart of the downlink transmission signal and control signal of the radio base station in which synchronization is maintained.

以下、本発明の実施の形態について、図面を参照しながら詳細に説明する。図１は、本実施形態の無線システムの概要図である。本無線システムは、すでに同期化されているTD-LTE無線基地局２００が構成する無線ネットワークの隣接局として、TD-LTE無線基地局３００が導入され、TD-LTE無線基地局２００から到来する下り同期信号４００に対して、TD-LTE無線基地局３００が同期および同期維持するケースを説明する。以下、TD-LTE無線基地局を、単に無線基地局と呼ぶ。   Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram of a wireless system according to this embodiment. In this radio system, a TD-LTE radio base station 300 is introduced as an adjacent station of a radio network formed by the already synchronized TD-LTE radio base stations 200, and downlinks coming from the TD-LTE radio base station 200 are introduced. A case where the TD-LTE radio base station 300 synchronizes and maintains synchronization with the synchronization signal 400 will be described. Hereinafter, the TD-LTE radio base station is simply referred to as a radio base station.

本実施形態の概要を説明する。無線基地局３００は、同期化された無線基地局２００であるDonor基地局からの下り同期信号を受信して基地局間同期を行う無線基地局である。ここでの基地局間同期は、無線基地局２００に無線基地局３００を同期させることである。無線基地局３００は、Donor基地局２００から受信した下り同期信号を検波し、同期検波タイミング情報を出力する。無線基地局３００は、Donor基地局２００との同期確立後に、同期検波タイミング情報を参照して、Donor基地局２００との同期タイミング差分を検出する。同期タイミング差分の補正が必要なときに、Donor基地局２００からの第１の下り同期信号を参照するために、無線基地局３００は、無線基地局３００が送信すべき下り同期信号の一部を送信停止する。   An outline of the present embodiment will be described. The radio base station 300 is a radio base station that receives a downlink synchronization signal from a Donor base station that is a synchronized radio base station 200 and performs inter-base station synchronization. Here, the synchronization between base stations is to synchronize the radio base station 300 with the radio base station 200. The radio base station 300 detects the downlink synchronization signal received from the Donor base station 200 and outputs synchronous detection timing information. After establishing synchronization with the Donor base station 200, the radio base station 300 refers to the synchronous detection timing information and detects a synchronization timing difference with the Donor base station 200. In order to refer to the first downlink synchronization signal from the Donor base station 200 when the synchronization timing difference needs to be corrected, the radio base station 300 uses a part of the downlink synchronization signal to be transmitted by the radio base station 300. Stop sending.

図１を参照して、無線通信ネットワークの構築エリアを説明する。図１において、無線通信ネットワーク２００−１および３００−１のエリアは、それぞれ無線基地局２００と３００によって構築される。無線基地局２００と無線基地局３００の間の伝搬路損失は、基地局と端末のアンテナ利得差や、無線基地局の設置条件が端末位置に比べ高所であり、見通しの良い条件であることを考慮すると、エリア境界に存在する端末１００との間の伝搬路損失と比しても少ない。伝搬路損失が少ないことを利用して、無線基地局３００は、すでに同期化された、隣接の無線基地局２００からの下り同期信号４００を参照して同期を確立し、エリア３００−１を構築する。   With reference to FIG. 1, the construction area of the wireless communication network will be described. In FIG. 1, the areas of the radio communication networks 200-1 and 300-1 are constructed by radio base stations 200 and 300, respectively. The propagation path loss between the radio base station 200 and the radio base station 300 is a favorable condition because the antenna gain difference between the base station and the terminal and the installation conditions of the radio base station are higher than the terminal position. Is less than the propagation path loss with the terminal 100 existing at the area boundary. Utilizing the fact that the propagation path loss is small, the radio base station 300 establishes synchronization with reference to the downlink synchronization signal 400 from the adjacent radio base station 200 that has already been synchronized, and constructs the area 300-1. To do.

図２は、無線基地局２００からの下り同期信号４００を参照する無線基地局３００の構成である。無線基地局３００は、ＲＦスイッチ３０８、同期検波部３０１、基準周波数生成部３０３、制御部３０４、およびＢＢ信号処理部３０５を有する。   FIG. 2 shows a configuration of the radio base station 300 that refers to the downlink synchronization signal 400 from the radio base station 200. The radio base station 300 includes an RF switch 308, a synchronous detection unit 301, a reference frequency generation unit 303, a control unit 304, and a BB signal processing unit 305.

ＲＦスイッチ３０８は、無線基地局３００において、ＴＤＤ方式のための送受信信号経路を切替えるスイッチであり、ＢＢ信号処理部３０５から出力される制御信号５０１によって送受信信号経路を切替える。ＲＦスイッチ３０８の初期状態、すなわち、無線基地局３００が同期確立される前のＳＢＹ（スタンバイ）状態は、非同期状態であるため、制御信号５０１が指示する経路は受信経路となるように選択され、無線基地局（Donor基地局）２００からの下り同期信号４００を受信する。   The RF switch 308 is a switch that switches transmission / reception signal paths for the TDD scheme in the radio base station 300, and switches transmission / reception signal paths by a control signal 501 output from the BB signal processing unit 305. Since the initial state of the RF switch 308, that is, the SBY (standby) state before the radio base station 300 is synchronously established is an asynchronous state, the path indicated by the control signal 501 is selected to be a reception path, A downlink synchronization signal 400 from the radio base station (Donor base station) 200 is received.

同期検波部３０１は、ＲＦスイッチ３０８を経由して受信した下り同期信号４００であるPSS(Primary Synchronization Signal)ならびにSSS(Secondary Synchronization Signal)の同期検波を行う。同期検波部３０１によって検出された同期検波タイミング情報は、制御部３０４に出力され、制御部３０４は、無線基地局３００自身の同期タイミングとの差分を検出し、同期タイミングの補正が必要か否かを判定する。制御部３０４による差分判定結果（差分と補正の要否）は、基準周波数生成部３０３に出力される。   The synchronous detection unit 301 performs synchronous detection of PSS (Primary Synchronization Signal) and SSS (Secondary Synchronization Signal), which are downlink synchronization signals 400 received via the RF switch 308. The synchronous detection timing information detected by the synchronous detection unit 301 is output to the control unit 304. The control unit 304 detects a difference from the synchronization timing of the radio base station 300 itself, and whether or not the synchronization timing needs to be corrected. Determine. The difference determination result (difference and necessity of correction) by the control unit 304 is output to the reference frequency generation unit 303.

基準周波数生成部３０３は、制御部３０４から入力する差分判定結果をもとに、無線基地局３００が必要とするタイミング精度範囲内に収まるように、端末１００との周波数同期維持範囲内で無線基地局３００の基準周波数を微調整する。   Based on the difference determination result input from the control unit 304, the reference frequency generation unit 303 performs radio base station within the frequency synchronization maintenance range with the terminal 100 so as to be within the timing accuracy range required by the radio base station 300. Fine-tune the reference frequency of station 300.

制御部３０４は、差分判定結果を基に、無線基地局３００が送出する下り同期信号PSSおよびSSSを一定周期毎に送信停止させる（制御信号５００を出力する）。この送信停止の周期は、制御部３０４の内部パラメータによって設定される。   Based on the difference determination result, the control unit 304 stops transmission of the downlink synchronization signals PSS and SSS transmitted from the radio base station 300 at regular intervals (outputs the control signal 500). This transmission stop period is set by an internal parameter of the control unit 304.

図３は、ＢＢ信号処理部３０５の構成図である。ＢＢ信号処理部３０５は、制御部３０４から、一定周期毎に送信停止させる制御信号５００を入力する
ＢＢ信号処理部３０５は、無線基地局３００の送受信信号のディジタル信号処理（説明を省略する3GPPに規定される上りＢＢ信号処理および下りＢＢ信号処理）を担うブロックである。PSSおよびSSSの信号送信を、制御信号５００によってＮＵＬＬ信号送信に切り替えるセレクタ３０６、セレクタ３０６で選択されたセレクタ出力信号をＩＦＦＴ（高速逆フーリエ変換）処理するＩＦＦＴ部３０７、およびＲＦスイッチ３０８の送受信経路を切替えるための制御信号５０１を出力するＴｘ／Ｒｘ切替信号生成部３０９を含む。 FIG. 3 is a configuration diagram of the BB signal processing unit 305. The BB signal processing unit 305 inputs a control signal 500 for stopping transmission at regular intervals from the control unit 304. The BB signal processing unit 305 performs digital signal processing of transmission / reception signals of the radio base station 300 (the description is omitted in 3GPP). It is a block responsible for upstream BB signal processing and downstream BB signal processing). Selector 306 that switches PSS and SSS signal transmission to NULL signal transmission by control signal 500, IFFT unit 307 that performs IFFT (fast inverse Fourier transform) processing on the selector output signal selected by selector 306, and transmission / reception path of RF switch 308 A Tx / Rx switching signal generation unit 309 that outputs a control signal 501 for switching between the two.

以上のような構成において、無線基地局３００が、無線基地局２００との間で実行する基地局間同期捕捉および同期維持について説明する。同期捕捉とは同期を確立する（同期確立状態に遷移する）過程を意味し、同期維持とは同期確立状態を継続する意味で用いる。   Inter-base station synchronization acquisition and synchronization maintenance performed by the radio base station 300 with the radio base station 200 in the above configuration will be described. The acquisition of synchronization means a process of establishing synchronization (transition to the synchronization establishment state), and the maintenance of synchronization is used to mean that the synchronization establishment state is continued.

図４は、同期捕捉ならびに同期維持に利用する、Donor基地局である無線基地局２００からの下り同期信号４００の例である。図４は、無線基地局３００の同期検波部３０１で検波する下り同期信号４００のフレーム構成と検出すべきPSS/SSSの信号を示す。同期捕捉ならびに同期維持の以下の説明では、無線基地局２００からの下り同期信号４００は、図４に示すように、3GPPで規定されるUL/DL Config設定値が4である。   FIG. 4 is an example of a downlink synchronization signal 400 from the radio base station 200 which is a Donor base station, which is used for synchronization acquisition and synchronization maintenance. FIG. 4 shows the frame structure of the downlink synchronization signal 400 detected by the synchronous detection unit 301 of the radio base station 300 and the PSS / SSS signal to be detected. In the following description of synchronization acquisition and synchronization maintenance, the downlink synchronization signal 400 from the radio base station 200 has a UL / DL Config setting value defined by 3GPP as shown in FIG.

TD-LTEシステムの下り同期信号４００は、１フレームを１０ｍｓとした構成であり、１フレームに１ｍｓのサブフレーム１０個（サブフレーム番号０〜９）を含む。UL/DL Config設定値が4のときの各サブフレームには、図示するＤ、ＵおよびＳがそれぞれ割当され、Ｄ及びＵのフレームを用いてDown Link信号及びUp Link信号が時分割複信（時分割による双方向通信）される。Ｓと表記するスペシャルサブフレームは、3GPPに規定されるSpecial subframe config設定値に従い、Down Link用、Up Link用、又はGuard用として利用される。TD-LTEシステムにおいては、図４に示すサブフレーム番号０と１のサブフレーム、およびサブフレーム番号５と６のサブフレームの２か所に、PSSとSSSが配置される。同期検波部３０１は、この信号（２か所のPSSとSSS）に対してスライディング相関をとることで同期検波する。   The downlink synchronization signal 400 of the TD-LTE system has a configuration in which one frame is 10 ms, and one frame includes 10 subframes (subframe numbers 0 to 9) of 1 ms. D, U, and S shown in the figure are assigned to each subframe when the UL / DL Config setting value is 4, and the Down Link signal and the Up Link signal are time-division duplexed using the D and U frames ( Bidirectional communication by time division). The special subframe denoted as S is used for Down Link, Up Link, or Guard according to the Special subframe config setting value defined in 3GPP. In the TD-LTE system, PSS and SSS are arranged in two locations, the subframes with subframe numbers 0 and 1 and the subframes with subframe numbers 5 and 6 shown in FIG. The synchronous detection unit 301 performs synchronous detection by taking a sliding correlation with respect to this signal (two PSS and SSS).

図５は、無線基地局３００の状態遷移を示すシーケンス図である。図５を参照しながら、無線基地局３００の同期捕捉手順を説明する。無線基地局３００は、起動直後はＳＢＹ状態として制御部３０４で管理され（S550）、Donor基地局である無線基地局２００からの下り同期信号４００を検出し（S551）、その後、無線基地局２００との間の伝搬遅延補正を行い、同期確立状態(ＡＣＴ)に遷移する（S552）。同期確立状態（ＡＣＴ）に遷移した後、同期維持制御を開始し（S553）、自身の無線基地局としての電波送出が可能となるが、ＳＢＹ状態からＡＣＴ状態への同期確立への遷移にあたっては、図５に示す同期手順Ａの段階にて、無線基地局３００の動作モードの確定（UL/DL Config情報取得）と、無線基地局２００との間の伝搬遅延補正が必要となる。   FIG. 5 is a sequence diagram illustrating state transition of the radio base station 300. The synchronization acquisition procedure of the radio base station 300 will be described with reference to FIG. The radio base station 300 is managed by the control unit 304 as an SBY state immediately after activation (S550), detects the downlink synchronization signal 400 from the radio base station 200 which is a Donor base station (S551), and then the radio base station 200 And a transition to the synchronization establishment state (ACT) is performed (S552). After transitioning to the synchronization establishment state (ACT), synchronization maintenance control is started (S553), and the radio transmission as its own radio base station is possible, but in transitioning from the SBY state to the synchronization establishment to the ACT state At the stage of the synchronization procedure A shown in FIG. 5, the operation mode of the radio base station 300 is determined (UL / DL Config information acquisition) and propagation delay correction between the radio base station 200 is required.

図６は、制御部３０４が実行する同期維持の制御手順を示すフローチャートである。まず、制御部３０４は、制御周期Ｔにより、同期維持の制御手順を繰り返し実行する。制御周期Ｔは、無線基地局３００と通信する、無線基地局３００配下の端末へのPSS/SSSの送信停止のための制御周期である。制御周期Ｔに従い、PSS/SSSの送信停止周期が定まる。制御周期Ｔは、無線基地局の電波環境や端末との無線データの送受信レベルに合わせて任意に設定する。   FIG. 6 is a flowchart showing a synchronization maintenance control procedure executed by the control unit 304. First, the control unit 304 repeatedly executes the control procedure for maintaining synchronization according to the control cycle T. The control period T is a control period for stopping transmission of PSS / SSS to terminals under the control of the radio base station 300 that communicate with the radio base station 300. According to the control cycle T, the PSS / SSS transmission stop cycle is determined. The control period T is arbitrarily set according to the radio wave environment of the radio base station and the transmission / reception level of radio data with the terminal.

制御部３０４は、図５に示す、制御部３０４で管理する、無線基地局３００のシステム状態（ＡＣＴ／ＳＢＹ）を判別する（S601）。システム状態がＳＢＹのときは、同期捕捉が完了していないので、制御部３０４は、処理を終了する。システム状態がＡＣＴのとき、制御部３０４は、図２に示した同期維持部３０２より入力する差分判定結果をもとに、タイミング差分補正が必要か否かを判定する（S602）。補正が必要なずれの時間を示す、判定するための閾値は、制御部３０４に設定したパラメータで任意に可変できる。タイミング差分補正が必要でない場合は、制御手順を終了する。   The control unit 304 determines the system state (ACT / SBY) of the radio base station 300 managed by the control unit 304 shown in FIG. 5 (S601). When the system state is SBY, since the synchronization acquisition is not completed, the control unit 304 ends the process. When the system state is ACT, the control unit 304 determines whether or not timing difference correction is necessary based on the difference determination result input from the synchronization maintaining unit 302 illustrated in FIG. 2 (S602). A threshold for determination indicating the time of deviation that needs to be corrected can be arbitrarily changed by a parameter set in the control unit 304. If timing difference correction is not necessary, the control procedure is terminated.

タイミング差分補正が必要な場合は、制御部３０４は、無線基地局３００の所定のタイミング精度範囲内に収まるよう、端末との周波数同期維持範囲内で無線基地局３００の基準周波数を、基準周波数生成部３０３に微調整させる（S603）。制御部３０４は、PSS/SSS送信停止を行うための制御信号５００をＢＢ信号処理部３０５に送信する（S604）。この制御信号５００は、図４に示すサブフレーム番号０と１のPSS/SSSを限定的に送信停止するような制御信号であり、サブフレーム番号５と６のPSS/SSSの送信停止はしない。制御信号５００は、ＢＢ信号処理部３０５の内部のＴｘ／Ｒｘ切替信号生成部３０９へも入力され、Ｔｘ／Ｒｘ切替信号生成部３０９は、ＰＳＳ／ＳＳＳ送信停止のタイミング区間中に（Null出力中に）、無線基地局２００からの下り同期信号を参照するためのＲＦスイッチ３０８用の制御信号５０１を生成する。たとえば、制御周期Ｔを４０ｍｓ（４サブフレーム毎）と設定した場合、同期維持動作中の無線基地局３００の下り送信信号、制御信号５００及び制御信号５０１のタイミングチャートは図７のようになる。制御信号５００の制御レベル“０”、“１”と、セレクタ３０６の“０”、“１”ポート番号とを連動させ、制御信号５０１は、“０”がＲｘ ｍｏｄｅ、“１”がＴｘ ｍｏｄｅとして動作する。   When the timing difference correction is necessary, the control unit 304 generates the reference frequency of the radio base station 300 within the frequency synchronization maintenance range with the terminal so as to be within the predetermined timing accuracy range of the radio base station 300. Fine adjustment is performed by the unit 303 (S603). The control unit 304 transmits a control signal 500 for stopping the PSS / SSS transmission to the BB signal processing unit 305 (S604). This control signal 500 is a control signal that stops transmission of the PSS / SSS of subframe numbers 0 and 1 shown in FIG. 4 in a limited manner, and does not stop transmission of PSS / SSS of subframe numbers 5 and 6. The control signal 500 is also input to the Tx / Rx switching signal generation unit 309 inside the BB signal processing unit 305, and the Tx / Rx switching signal generation unit 309 performs the NSS output during the PSS / SSS transmission stop timing period. ), A control signal 501 for the RF switch 308 for referring to the downlink synchronization signal from the radio base station 200 is generated. For example, when the control cycle T is set to 40 ms (every 4 subframes), the timing chart of the downlink transmission signal, the control signal 500, and the control signal 501 of the radio base station 300 during the synchronization maintaining operation is as shown in FIG. The control levels “0” and “1” of the control signal 500 are linked to the “0” and “1” port numbers of the selector 306, and the control signal 501 is “0” for Rx mode and “1” for Tx mode. Works as.

図６及び図７で説明した一連の動作を、制御部３０４に設定する制御周期Ｔ毎に繰り返し実行することで、端末との同期維持を継続しつつ、無線基地局２００との同期維持を行うことができる。   By repeating the series of operations described in FIG. 6 and FIG. 7 for each control cycle T set in the control unit 304, the synchronization with the radio base station 200 is maintained while maintaining the synchronization with the terminal. be able to.

上述した実施例では、４サブフレーム毎の同期維持動作としているが、制御周期Ｔは無線基地局３００にて可変できるので、無線基地局の基準周波数精度や、様々な設置環境に応じて適用可能である。   In the above-described embodiment, the synchronization maintaining operation is performed every four subframes. However, since the control cycle T can be changed in the radio base station 300, it can be applied according to the reference frequency accuracy of the radio base station and various installation environments. It is.

１００…端末、２００…Ｄｏｎｏｒ基地局、３００…無線基地局、３０１…同期検波部、３０３…基準周波数生成部、３０４…制御部、３０５…ＢＢ信号処理部、３０６…セレクタ、３０７…ＩＦＦＴ部、３０８…ＲＦスイッチ、３０９…Ｔｘ／Ｒｘ切替信号生成部、４００…Ｄｏｎｏｒ基地局からの下り同期信号、５００…ＰＳＳ／ＳＳＳ送信用制御信号、５０１…ＲＦスイッチ切替用制御信号。   DESCRIPTION OF SYMBOLS 100 ... Terminal, 200 ... Donor base station, 300 ... Radio base station, 301 ... Synchronous detection part, 303 ... Reference frequency generation part, 304 ... Control part, 305 ... BB signal processing part, 306 ... Selector, 307 ... IFFT part, 308... RF switch, 309... Tx / Rx switching signal generator, 400... Downlink synchronization signal from Donor base station, 500... PSS / SSS transmission control signal, 501.

Claims (8)

同期化された他のTD-LTE無線基地局であるDonor基地局からの第１の下り同期信号を受信して基地局間同期を行うTD-LTE無線基地局であって、
前記Donor基地局から受信した前記第１の下り同期信号を検波し、同期検波タイミング情報を出力する同期検波部、および
前記Donor基地局との同期確立後に、前記同期検波タイミング情報を参照して、前記Donor基地局との同期タイミング差分を検出し、前記同期タイミング差分の補正が必要なときに、前記Donor基地局からの前記第１の下り同期信号を参照するために、該TD-LTE無線基地局が送信する第２の下り同期信号の一部を送信停止する制御部を備えることを特徴とするTD-LTE無線基地局。 A TD-LTE radio base station that receives a first downlink synchronization signal from a Donor base station that is another synchronized TD-LTE radio base station and performs inter-base station synchronization,
Detecting the first downlink synchronization signal received from the Donor base station, and outputting the synchronous detection timing information, and after establishing synchronization with the Donor base station, refer to the synchronous detection timing information, The TD-LTE radio base station detects a synchronization timing difference with the Donor base station and refers to the first downlink synchronization signal from the Donor base station when the synchronization timing difference needs to be corrected. A TD-LTE radio base station comprising a control unit that stops transmission of a part of a second downlink synchronization signal transmitted by a station. 請求項１に記載のTD-LTE無線基地局であって、前記同期タイミング差分の補正が必要なときに、該TD-LTE無線基地局の基準周波数を調整する基準周波数生成部を備えることを特徴とするTD-LTE無線基地局。   The TD-LTE radio base station according to claim 1, further comprising a reference frequency generation unit that adjusts a reference frequency of the TD-LTE radio base station when the synchronization timing difference needs to be corrected. TD-LTE radio base station. 請求項２に記載のTD-LTE無線基地局であって、前記制御部は、前記Donor基地局からの前記第１の下り同期信号を受信するための、該TD-LTE無線基地局から送信する前記第２の下り送信信号の一部を送信停止する周期は、該制御部に設定される可変パラメータによることを特徴とするTD-LTE無線基地局。   The TD-LTE radio base station according to claim 2, wherein the control unit transmits from the TD-LTE radio base station for receiving the first downlink synchronization signal from the Donor base station. The period for stopping transmission of a part of the second downlink transmission signal depends on a variable parameter set in the control unit, TD-LTE radio base station. 請求項３に記載のTD-LTE無線基地局であって、該TD-LTE無線基地局が送信する前記第２の下り同期信号の一部は、該TD-LTE無線基地局と通信する配下の端末に向けて送信する同期信号であるPSS(Primary Synchronization Signal)及びSSS(Secondary Synchronization Signal)の一部であることを特徴とするTD-LTE無線基地局。   The TD-LTE radio base station according to claim 3, wherein a part of the second downlink synchronization signal transmitted by the TD-LTE radio base station is under control of communication with the TD-LTE radio base station. A TD-LTE radio base station which is a part of PSS (Primary Synchronization Signal) and SSS (Secondary Synchronization Signal) which are synchronization signals transmitted to a terminal. 同期化された他のTD-LTE無線基地局であるDonor基地局からの第１の下り同期信号を受信するTD-LTE無線基地局の基地局間同期方法であって、該TD-LTE無線基地局は、
前記Donor基地局から受信した前記第１の下り同期信号を検波し、同期検波タイミング情報を出力し、
前記Donor基地局との同期確立後に、前記同期検波タイミング情報を参照して、前記Donor基地局との同期タイミング差分を検出し、
前記同期タイミング差分の補正が必要なときに、前記Donor基地局からの前記第１の下り同期信号を参照するために、該TD-LTE無線基地局が送信する第２の下り同期信号の一部を送信停止することを特徴とするTD-LTE無線基地局の基地局間同期方法。 A synchronization method between base stations of a TD-LTE radio base station that receives a first downlink synchronization signal from a Donor base station that is another synchronized TD-LTE radio base station, the TD-LTE radio base The station
Detecting the first downlink synchronization signal received from the Donor base station, and outputting synchronous detection timing information;
After establishing synchronization with the Donor base station, with reference to the synchronous detection timing information, detect a synchronization timing difference with the Donor base station,
Part of the second downlink synchronization signal transmitted by the TD-LTE radio base station to refer to the first downlink synchronization signal from the Donor base station when the synchronization timing difference needs to be corrected TD-LTE radio base station synchronization method between base stations, characterized in that the transmission is stopped. 請求項５に記載のTD-LTE無線基地局の基地局間同期方法であって、前記同期タイミング差分の補正が必要なときに、該TD-LTE無線基地局の基準周波数を調整することを特徴とするTD-LTE無線基地局の基地局間同期方法。   6. The inter-base station synchronization method for a TD-LTE radio base station according to claim 5, wherein the reference frequency of the TD-LTE radio base station is adjusted when the synchronization timing difference needs to be corrected. TD-LTE wireless base station synchronization method between base stations. 請求項６に記載のTD-LTE無線基地局の基地局間同期方法であって、前記Donor基地局からの前記前記第１の下り同期信号を受信するための、該TD-LTE無線基地局から送信する前記前記第２の下り送信信号の一部を送信停止する周期は、該TD-LTE無線基地局に設定される可変パラメータによることを特徴とするTD-LTE無線基地局の基地局間同期方法。   7. The inter-base station synchronization method for a TD-LTE radio base station according to claim 6, wherein the TD-LTE radio base station receives the first downlink synchronization signal from the Donor base station. A period for stopping transmission of a part of the second downlink transmission signal to be transmitted depends on a variable parameter set in the TD-LTE radio base station. Method. 請求項７に記載のTD-LTE無線基地局の基地局間同期方法であって、該TD-LTE無線基地局が送信する前記第２の下り同期信号の一部は、該TD-LTE無線基地局と通信する配下の端末に向けて送信する同期信号であるPSS(Primary Synchronization Signal)及びSSS(Secondary Synchronization Signal)の一部であることを特徴とするTD-LTE無線基地局の基地局間同期方法。   8. The inter-base station synchronization method for a TD-LTE radio base station according to claim 7, wherein a part of the second downlink synchronization signal transmitted by the TD-LTE radio base station is the TD-LTE radio base station. Inter-base station synchronization of TD-LTE radio base stations characterized by being part of PSS (Primary Synchronization Signal) and SSS (Secondary Synchronization Signal) which are synchronization signals transmitted to the terminal under control communicating with the station Method.
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Publication number Priority date Publication date Assignee Title
JP2020523821A (en) * 2017-06-08 2020-08-06 クアルコム，インコーポレイテッド Techniques and apparatus for configuring resources for synchronization in a wireless backhaul network

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020523821A (en) * 2017-06-08 2020-08-06 クアルコム，インコーポレイテッド Techniques and apparatus for configuring resources for synchronization in a wireless backhaul network

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