KR20000009678A - Dual searcherof direct sequence code division multiple access method - Google Patents
Dual searcherof direct sequence code division multiple access method Download PDFInfo
- Publication number
- KR20000009678A KR20000009678A KR1019980030245A KR19980030245A KR20000009678A KR 20000009678 A KR20000009678 A KR 20000009678A KR 1019980030245 A KR1019980030245 A KR 1019980030245A KR 19980030245 A KR19980030245 A KR 19980030245A KR 20000009678 A KR20000009678 A KR 20000009678A
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- searcher
- dual
- code
- serial
- multiple access
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
- H04B1/7083—Cell search, e.g. using a three-step approach
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
- H04B1/7075—Synchronisation aspects with code phase acquisition
Abstract
Description
본 발명은 직접 시퀀스 부호 분할 접속 방식의 수신기에 관한 것으로, 특히 초기동기 시간을 줄일 수 있는 듀얼 탐색기에 관한 것이다.The present invention relates to a receiver of a direct sequence code division access method, and more particularly, to a dual searcher capable of reducing initial synchronization time.
코드분할다중접속(Code Division Multiple Access : CDMA) 방식의 시스템은, 송신하고자 하는 데이터를 가상잡음(PsudoNoise : PN) 코드를 이용하여 더 넓은 대역으로 확산하여 전송하고, 수신측에서는 전송된 가상잡음 코드와 동일한 코드로 역확산하여 원신호를 복원하게 된다. 여기서 수신된 PN코드와 수신부에서 생성된 PN코드의 정확한 동기가 중요한데, 이를 맞추기 위한 처리를 동기과정(synchronization)이라 한다. 이 동기과정은 한칩 이내로 듬성하게(coarse alignment) 동기를 맞추는 초기동기(acquisition) 과정과 한칩 이내에서 정확하게(fine alignment) 동기를 맞추는 동기 추적(tracking)과정 으로 분류된다.In the code division multiple access (CDMA) system, the data to be transmitted is spread and transmitted in a wider band using a pseudonoise (PN) code, and at the receiving side, Despreading with the same code restores the original signal. Here, the exact synchronization of the received PN code and the PN code generated by the receiver is important, and the process for matching them is called synchronization. This synchronization process is classified into an initial synchronization process of coarse alignment within one chip and a tracking process of fine alignment synchronization within one chip.
본 특허에서 제시한 방식은 이중 초기동기과정에 대한 것으로 현재 무선가입자망의 파일롯 채널 구조하에서 효율적으로 초기동기를 획득하기 위한 것이다.The method proposed in this patent is for a dual initial synchronization process to efficiently acquire initial synchronization under a pilot channel structure of a current wireless subscriber network.
일반적으로 초기동기획득방식으로는 직렬탐색(serial search)방식, 순차적예측(sequential estimation) 방식, 정합필터탐색(matched filter searcher) 이라는 3가지 방식이 있는데, 기존의 CDMA 디지털 이동통신 시스템들은 비록 초기동기과정에 시간이 많이 소요된다는 단점이 있지만, 하드웨어 구성의 간편함과 낮은 신호대 잡음비에서도 성능이 우수하다는 장점 때문에 대부분 직렬탐색(serial search)방식을 채택하고 있다.In general, there are three types of initial synchronization acquisition methods, serial search, sequential estimation, and matched filter searcher. Although the process takes a long time, the serial search method is mostly adopted because of the simplicity of the hardware configuration and the excellent performance even at a low signal-to-noise ratio.
현재, 광대역 코드분할다중접속(Wideband CDMA) 기술을 사용하는 국내무선가입자망(Wireless Local Loop : WLL) 잠정 표준(interim standard)에서의 파일롯 구조를 우선 살펴보자. 파일롯 구조는 확산 코드는 232-1의 긴 PN 코드를 사용하고, 이를 도1에서와 같이 중복되지 않은 20mse 구간 만큼의 단축 시퀀스(shortened sequence)를 한 기지국에서 사용하게 된다. 이렇게 함으로써 기지국간에는 비동기로 동작을 하고, 각 기지국간에 다른 PN코드를 할당하는 효과를 가져온다. 하지만, 이런 파일롯 구조하에서는 위상의 불확실성(uncertainty) 뿐만아니라 코드의 불확실성으로 인하여 종래의 직렬 탐색 방식만으로는 초기동기시 많은 시간이 걸리게 된다. 이렇듯 종래에는 직렬탐색기 또는 정합필터 탐색기를 사용하였으나, 이렇게 코드 및 위상의 불확실성이 클 경우, 직렬탐색기 하나만으로는 탐색시간이 너무 많이 걸린다는 단점이 있고, 정합필터 탐색기만을 이용할 경우, 전력의 소비가 크다는 단점이 있다.At present, let's first look at the pilot structure in the Wireless Local Loop (WLL) interim standard using Wideband CDMA technology. The pilot structure uses a long PN code of 2 32 -1 as a spreading code, and uses a shortened sequence of 20 mse intervals, which is not duplicated, in one base station as shown in FIG. 1. In this way, the base station operates asynchronously, and has the effect of assigning a different PN code to each base station. However, under this pilot structure, not only the uncertainty of the phase but also the uncertainty of the code, the conventional serial search alone takes a lot of time during initial synchronization. As such, although a serial searcher or a matched filter searcher is used in the past, when the uncertainty of code and phase is large, a single search for the serial searcher takes too much time, and when only the searched filter searcher is used, power consumption is large. There are disadvantages.
따라서, 본 발명은 듀얼탐색기를 이용함으로써 무선가입자망의 파일롯 채구조하에서 초기동기 획득 시간을 줄이는데 그 목적이 있다.Accordingly, an object of the present invention is to reduce the initial synchronization acquisition time under a pilot channel structure of a wireless subscriber network by using a dual searcher.
도1은, 국내 무선가입자망의 파일롯 채널 구조,1 is a pilot channel structure of a domestic wireless subscriber network,
도2는, 듀얼탐색기 전체적인 구성도이다.2 is an overall configuration diagram of a dual searcher.
*도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings
10 : 정합필터탐색기 12 : 직렬탐색기10: matched filter searcher 12: serial searcher
14 : 탐색기 제어기 16 : 스위치14 Explorer Controller 16 Switch
본 발명은 듀얼탐색 방식을 제시한다. 이는 직렬 탐색기 뿐만 아니라 병렬탐색기인 정합필터 탐색기도 포함한다. 우선 정합필터 탐색기를 이용하여 단말기가 어느 셀에 속해 있는지 코드를 찾는다. 그런 다음 그 찾아진 코드 안에서 직렬탐색기로 코드 위상을 찾아 동기를 획득한다.The present invention provides a dual search method. This includes not only the serial searcher but also the matched filter searcher, which is a parallel searcher. First, a code is searched for which cell the terminal belongs to using the matched filter searcher. Then, within the found code, serial code is used to find the code phase to obtain synchronization.
정합필터 탐색기는 비교적 많은 전력을 소비하므로, 처음에 코드를 찾을 경우에만 사용을 하고, 코드가 찾아진 다음의 일련의 동작은 직렬탐색기가 담당함으로 해서, 소비전력 및 동기획득 시간에서 최적의 점을 구한다.The matched filter searcher consumes a relatively large amount of power, so it is used only when the code is first found, and the next series of operations that the code finds is taken care of by the serial explorer so that the optimal point in power consumption and acquisition time can be found. Obtain
이하, 도2를 참조하여 본 발명의 일 실시예를 상세히 설명한다.Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. 2.
도2에 도시된 바와 같이, 처음에는 스위치(16)가 위로 향해져 있어서, 정합필터 탐색기(10)를 동작시킨다. 정합필터 탐색기(10)는 탐색기제어기(searcher controller)(14)로부터 기지국에서 사용하고 있는 코드에 해당하는 후보 시드를 받아서 탐색을 시작한다(참조 : 정합필터 탐색기는 본 출원인이 1997년 12월 29일자로 출원한 특허 97-75797호에 상세히 설명되어 있으므로 여기서 상세한 설명은 생략한다). 정합필터 탐색기(10)가 코드를 찾아 록 인터럽트를 발생하면, 탐색기 제어기(14)는 스위치(16)를 아래로 향하게 하고 직렬탐색기(12)를 동작시킨다.As shown in Fig. 2, the switch 16 is initially turned upward to operate the matched filter searcher 10. As shown in FIG. The matched filter searcher 10 receives a candidate seed corresponding to the code being used in the base station from the searcher controller 14 and starts searching. (Refer to the matched filter searcher, which is filed on December 29, 1997. It is described in detail in Patent No. 97-75797, which is omitted herein. When the matched filter searcher 10 finds a code and generates an interrupt, the searcher controller 14 turns the switch 16 down and operates the serial searcher 12.
이때 탐색기제어기(14)는 찾아진 코드에 해당하는 시드를 직렬탐색기로 넘겨주어, 직렬탐색기(12)는 그 코드 내에서 위상 동기를 찾게 된다.At this time, the searcher controller 14 passes the seed corresponding to the found code to the serial searcher, and the serial searcher 12 finds phase synchronization in the code.
상기와 같은 본 발명은, 코드분할 다중접속 수신시스템에서 듀얼탐색기를 채택함으로써 동기 시간을 줄이는 효과 뿐만 아니라 정합필터 탐색기만을 이용할 경우보다 소비전력을 줄이는 효과가 있다.The present invention as described above, the dual search in the code division multiple access receiving system has the effect of reducing not only the synchronization time but also the power consumption than using only the matched filter searcher.
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| Application Number | Priority Date | Filing Date | Title |
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| KR1019980030245A KR100278817B1 (en) | 1998-07-28 | 1998-07-28 | Dual Seeker for Receiver with Direct Sequence Code Division Access |
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| Application Number | Priority Date | Filing Date | Title |
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| KR1019980030245A KR100278817B1 (en) | 1998-07-28 | 1998-07-28 | Dual Seeker for Receiver with Direct Sequence Code Division Access |
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| KR20000009678A true KR20000009678A (en) | 2000-02-15 |
| KR100278817B1 KR100278817B1 (en) | 2001-01-15 |
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