CN1130032C - 在cdma通信系统中与基站定时同步的方法 - Google Patents
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Abstract
在本发明中,在参考基站(62)和从属基站(64)之间的软切换区域中,从属基站(64)通过由移动站(60)发送并接收的消息,捕获与参考基站(62)的同步。首先,由参考基站(62)测量在移动站(60)和参考基站(62)之间的往返行程延迟。一旦移动站(60)捕获来自从属基站(64)的信号,它测量和报告在信号从参考基站(62)到它所需时间和信号从从属基站(64)到它所需的时间之差。最后所需的测量是由从属基站(64)测量在它接收来自移动站(60)的反向链路信号的时间和它把信号发送到移动站的时间之间的时差。这里详细描述对于测得时间值的一系列计算来确定在从属基站(64)和根据它调节从属基站(64)定时之间的时差。
Description
发明领域
本发明涉及通信系统。具体地说,本发明涉及用于利用从同时与同步基站进行通信的移动站发送的信号使基站同步新的和经改进的方法和装置。
相关技术描述
运用码分多址(CDMA)调制技术只是方便其中存在大量系统用户的通信的几种方法中的一种。虽然已知其他技术,诸如时分多址(TDMA)、频分多址(FDMA)和诸如幅度压扩单边带(ACSSB)的AM调制方案,但是CDMA具有优于这些其他调制技术的显著优点。在美国专利第4,901,307号(发明名称为“运用卫星或地面中继站的扩展频谱多址通信系统”)和美国专利第5,103,459号(发明名称为“用于在CDMA蜂窝状电话系统中产生信号波形的系统和方法”)中揭示了在多址通信系统中的对CDMA技术的运用,其中上述两项专利转让给本发明的受让人,并作为参考资料在此引入。在美国由电信工业协会在TIA/EIA/IS-95-A名为“用于双模式宽带扩展频谱蜂窝状系统的移动站-基站兼容性标准”中,标准化用于提供CDMA移动通信的方法,这里称为IS-95。
在上述专利中,揭示多址技术,其中多个移动站用户运用码分多址(CDMA)扩展频谱通信信号通过卫星中继站或地面基站(已知为小区基站或区站)进行通信,其中每个移动站用户具有收发机。通过运用CDMA通信,可重新使用频谱达多次,从而允许增加系统用户容量。对CDMA技术的运用导致高于运用其他多址技术可捕获的频谱效率。
在美国专利第5,109,390中(’390专利)(发明名称为“在CDMA蜂窝状通信系统中分集接收机”,已转让给本发明的受让人,并作为参考资料在此引入)中揭示了用于同步解调已从一个基站沿着不同传播路径传播(travel)的数据并用于同步解调在多于一个的基站冗余提供的数据的一种方法。在第390专利中,将分开解调的信号组合起来,以提供对发送数据的估计,其可靠性高于通过任一路径或来自任一基站的解调数据。
一般,可将切换分成两种-硬切换和软切换。在硬切换过程中,当移动站离开初始(origination)基站并进入目的地基站时,移动站断开与初始基站的通信链路,此后建立与目的地基站的新通信链路。在软切换过程中,在断开与初始基站的通信链路之前,移动站完成与目的地基站的通信链路。于是,在软切换过程中,在一些时间期间内,移动站与初始基站和目的地基站冗余地进行通信。
比起硬切换,软切换不大可能丢失(drop)呼叫。此外,当移动站在基站的覆盖区边界附近行进时,它响应于环境中的小变化来进行重复切换请求。通过软切换还大大减少了被称为乒乓(ping-ponging)的这种问题。在美国专利第5,101,501号(发明名称为“用于在CDAM蜂窝状电话系统中的通信中提供软切换的方法和系统”,已转让给本发明的受让人,并作为参考资料在此引入)中详细描述用于执行软切换的处理。
在美国专利第5,267,261号(发明名称为“在CDMA蜂窝状通信系统中的移动站辅助软切换”,已转让给本发明的受让人,并作为参考资料在此引入)中揭示经改进的软切换技术。在第261号专利的系统中,通过测量由每个基站在移动站处发送的“导频”信号的强度,改进软切换处理。这些导频强度测量通过方便对可行基站切换候选者的确认,来辅助软切换处理。
可将基站候选者分成4组。第一组,称为现行组,包括正与移动站进行通信的基站。第二组,称为候选者组,包括将其信号确定为具有对移动站有用但不是当前使用的足够强度的基站。当它们的测定导频能量超出预定门限TADD时,把基站添加到候选组。第三组是基站组,它们在移动站附近(而且不包括在现行组或候选组中)。而且第四组是包含所有其他基站的剩余组。
在IS-95中,基站候选者的特征在于它的导频信道的伪噪声(PN)序列的相位偏置。当移动站搜索确定来自候选者基站的导频信号的强度时,它执行相关操作,其中将滤波接收信号与PN偏置假设组相关。在待批美国专利申请序号08/687,694号(1996年7月26日申请,发明名称为“用于在CDMA通信系统中执行搜索捕获(search acquisition)的方法和装置”,已转让给本发明的受让人并作为参考资料在此引入)中详细描述用于执行相关操作的方法和装置。
在基站和移动站之间的传播延迟是未知的。该未知延迟产生在PN码中的未知移位。搜索处理尝试确定在PN码中的未知移位。为了这样做,移动站及时动移它的搜索器PN码发生器的输出。将搜索移位的范围称为搜索窗口。该搜索窗口以PN移位假设为中心。基站把物理近似地表示基站导频的PN偏置的消息发送到移动站。该移动站将使它的搜索窗口以PN偏置假设为中心。
搜索窗口的适当尺寸依赖于几个因素,它包括导频的优先权、搜索处理器的速度和多路径到达的预期延迟扩展(delay spread)。CDMA标准(IS-95)定义三个搜索窗口参数。由搜索窗口“A”管理现行和候选组中的导频搜索。在窗口“N”范围内搜索邻近组导频,和在窗口“R”范围内搜索剩余组导频。在下表1中提供搜索器窗口尺寸,其中码片是
SRCH_WIN_ASRCH_WIN_NSRCH_WIN_R | 窗口尺寸(PN码片) | SRCH_WIN_ASRCH_WIN_NSRCH_WIN_R | 窗口尺寸(PN码片) |
0 | 4 | 8 | 60 |
1 | 6 | 9 | 80 |
2 | 8 | 10 | 100 |
3 | 10 | 11 | 130 |
4 | 14 | 12 | 160 |
5 | 20 | 13 | 226 |
6 | 28 | 14 | 320 |
7 | 40 | 15 | 452 |
表1
窗口尺寸定位(sizing)是在搜索速度和丢失在搜索窗口之外的强路径的概率之间的折中。
基站把规定PN假设的消息发送到移动站,其中上述假设这移动站应相对于它自己的PN偏置进行搜索。例如,初始基站可命令移动站在自己的PN偏置之前,搜索导频128PN码片。作为响应,移动站把它的搜索器解调器128码片设置在输出码片循环之前,并运用以特定偏置为中心的搜索窗口来搜索导频。一旦命令移动站搜索PN假设来确定执行切换可捕获的资源,那么目的地基站导频的PN偏置在时间上十分接近有向偏置是十分关键的。在靠近基站边界的搜索速度是十分重要的,因为完成所需搜索的延迟导致丢失呼叫。
在美国的CDMA系统中,通过使每个基站设有全球定位卫星(GPS)接收机捕获该基站同步。然而,存在基站可能不能接收GPS信号的情况。例如,在地铁和隧道内,GPS信号衰减到禁止将它们用于定时同步基站或微型基站的程度。本发明提供用于在一小部分网络能够接收集中定时信号并从中捕获定时以及一部分基站不能接收集中定时信号的情况下,提供定时同步的方法和系统。
发明概述
本发明是用于时间同步基站的一种新颖和经改进的方法和装置,其中上述基站不能在网络中接收集中定时信号,而一些基站能够接收集中定时信号。参考基站通过接收集中定时信号或其他装置具有定时同步。在示例实施例中,参考基站运用全球定位卫星(GPS)接收机同步。例如由于不能接收集中定时信号,所以从属基站没有同步的能力。
在本发明中,在参考基站和从属基站之间的软切换区域中,从属基站通过由移动站发送并接收的消息,捕获与参考基站的同步。首先,由参考基站测量在移动站和参考基站之间的往返行程延迟。接着,从属基站进行搜索,直至它捕获由移动站发送的信号,称为反向链路信号。响应于捕获反向链路信号,从属基站调节它的定时,从而移动站可以捕获它的信号,称为前向链路信号。如果在从属基站中的定时误差不严重,那么该步骤是不必要的。
一旦移动站捕获来自从属基站的信号,它测量和报告在信号从参考基站到它所需时间和信号从从属基站到它所需的时间之差。最后所需的测量是由从属基站测量在它接收来自移动站的反向链路信号的时间和它把信号发送到移动站的时间之间的时差。
这里详细描述对于测得时间值的一系列计算来确定在从属基站和根据它调节从属基站定时之间的时差。应注意,在IS-95CDMA通信系统的正常操作期间,执行所述的所有测量。
附图说明
结合附图,从下面的详细描述中,本发明的特性、目的和优点将显而易见,其中在附图中相同标号做相应表示:
图1是示出包含参考基站和从属基站的无线通信系统的网络结构的方框图;
图2是示出在移动站、同步基站和异步基站以及相应时间间隔之间的各种传送的示图;
图3是示出用于使不能接收集中定时信号的基站同步的方法的流程图;
图4是本发明的移动站的方框图;
图5是在本发明的移动站中的搜索器的方框图;
图6是本发明的移动站的话务信道调制器的方框图;
图7是本发明的基站的方框图;
图8是本发明的基站的传送系统的方框图;和
图9是本发明的基站的接收机系统的方框图。
较佳实施例的详细描述
I.定时误差计算的概观
参照图1,移动站60与基站62进行通信,同时它大约位于由基站覆盖边界61勾勒的覆盖区内。通过利用诸如全球定位系统(GPS)的中心定时系统,将基站62与网络的其余部分同步。相反,基站64没有与中心定时系统同步。通过利用T1线路或其他装置,基站控制器66把来自PSTN的呼叫送到基站62或64。此外,通过T1线路,向基站64提供频率同步。
对于短时间期间,利用现有技术中已知的方法,通过T1线路,可使频率同步具有可接受的精确度。然而,在这些方案中,对于提供频率信息来说,假信号(glitch)是很普遍的。这些假信号导致通过利用本发明可校正的定时误差。由于在相位和频率之间的关系,本发明的相位间歇校正允许在需要时利用较不精确的频率源。
参照图2,它示出用于使从属基站64的定时和参考基站62的同步定时同步的传输和相应时间间隔。信号路径500示出从参考基站62到移动站60的前向链路的传输。发生这种传输的时间间隔指定为τ1。在移动站60处,时间将在反向链路上的帧传输的开始时间与在前向链路上的帧到达的开始时间对准。在IS-95中标准化该时间对准,和加入符合它设计的硬件,从而在现有技术中已知执行该对准的方法和装置。
传输502示出反向链路帧从移动站60到参考基站62的传输。信号500从基站62到移动站60(τ1)的时间等于信号502从基站62到移动站60(还是τ1)的时间。由于基站62知道它发送信号500的时间,而且知道它接收信号502的时间,所以基站62可以计算往返行程(round trip)延迟时间(RTD1),它是计算时间误差(τ0′-τ0)所需的第一值。
信号路径504是反向链路信号从移动站60沿着不同传播路径到从属基站64的反向链路信号传输。将信号504从移动站60传播到从属基站64所需时间指定为τ2。将反向连路信号504到达基站64的时间指定为T2。前向链路信号506从基站64到移动站60所需时间等于τ2。此外,从属基站64可以测量在它接收来自移动站60的反向连路信号的时间和它将它的前向链路信号发送到移动站60之间的时差。将该时差指定为RTD2。已知这些时间允许计算时间误差(τ0′-τ0)。下面描述用于计算时间误差τ0′的方法。
首先,从图2得出:
T2=τ1+τ2,和 (1)
τ1+ΔT=T0′+T2 (2)
通过操纵等式(1)和(2)的项,得出以下等式:
T2+ΔT=T0′+2·τ2 (3)
2·τ2=T2T0′+ΔT (4)
简化符号,将新可变RTD2定义为RTD2=T2-T0′ (5)
RTD2=T2-T0′ (5)
从图2可见:
T2=T0+τ1+τ2 (7)
因此,
T2-T0=τ1+τ2,和 (8)
RTD2=2·τ2-ΔT
通过替换,时间误差(T0′-T0)等于:
T0′-T0=τ1-τ2+ΔT (9)
一旦基站64知道它的定时误差量(T0′-T0),它调节它的定时,从而使它与基站62的定时同步。这些测量可能是错误的,所以,在较佳实施例中,冗余地做多个测量来保证定时校正精确度。
现在,描述用于测量在等式(12)中每个所需时间值的方法和装置。
II.测量往返行程延迟(RTD1)
图3是示出用于使从属基站64与参考基站62的定时同步的本发明的方法的流程图。在步骤300中,开始同步方法,移动站60与参考基站62进行通信并落在范围内以指导与从属基站64的通信。在步骤302中,测量信号从参考基站62到移动站60以及从移动站60到参考基站62的往返行程延迟(RTD1)时间。通过将由移动站60接收到的帧的帧边界与由移动站60发送的帧的帧边界对准,可以做到这点。在现有技术中已知用于提供这种对准的方法和装置。于是,测量往返行程延迟(RTD1)作为在由参考基站62发送的帧的开始时间和由参考基站62从移动站60接收到的帧的开始时间之间的时差。
参照图4,在天线2处接收来自参考基站62的数据的前向链路帧,而且通过双工器3向接收机(RCVR)4提供。接收机4下变频、过滤和放大接收信号并向搜索器50和话务解调器(TRAFFIC DEMODS)54提供。搜索器50根据由参考基站62提供的邻近组搜索导频信道。提供邻近组列表作为在话务信道上的来自参考基站62的信令数据。向控制处理器55提供表示来自参考基站62的接收帧的开始的信号。控制处理器55产生并向话务调制器58提供时间对准信号,它将从移动站60发送的帧的开始时间与在移动站60处接收到的帧的开始时间对准。
向话务调制器58提供来自移动站60的用户的数据帧,其中话务调制器58响应于来自控制处理前55的定时信号,时间对准通过发射机(TMTR)56发送的帧与由移动站60从参考基站62接收到的帧。由发射机56上变频、滤波和放大反向链路帧,然后通过双工器提供来通过天线2发送。
III.由从属基站捕获移动站
图6示出移动站60的话务信道调制器58。向帧格式器200提供数据帧。在示例实施例中,帧格式器200产生并附上一组循环冗余(CRC)校验位,而且产生一组尾位。在示例实施例中,帧格式器200遵循在IS-95中标准化的帧格式协议,而且在美国专利第5,600,754号(发明名称为“用于排列声码器数据来屏蔽传输信道引发误差的方法和系统”,已转让给本发明的受让人,并作为参考资料在此引入)中详细描述。
向编码数据用于纠错和检错的编码器202提供格式化数据帧。在示例实施例中,编码器202是卷积编码器。向根据预定交错格式重新排序码元的交错器204提供编码数据码元。向Walsh映射器206提供重新排序的码元。在示例实施例中,Walsh映射器206接收八个编码码元,而且把该码元组映射到64码片Walsh序列。向根据长扩展码来扩展Walsh码元的扩展装置208提供Walsh码元。长PN码发生器210产生伪随机(PN)序列,它扩展数据并把该数据与来自邻近的其他移动站的反向链路发送数据区分开来。
在示例实施例中,根据四相移相键控(QPSK)调制格式发送数据,其中根据短PN序列扩展I和Q信道。向根据分别由PN发生器(PN1和PNQ)212和218提供的短PN序列对数据执行第二扩展操作的扩展装置214和216提供扩展数据。
在步骤304中,从属基站64捕获由移动站60发送的反向链路信号。基站控制器66把信号发送到从属基站64,它表示移动站62用来扩展它的反向链路信号的PN码偏置。响应于来自基站控制器66的这信号,从属基站64搜索以由来自基站控制器66的信号表示的PN偏置为中心的移动站60。
在示例实施例中,从属基站64根据来自基站控制器66的信号,组装载(bank load)它的搜索器长码PN发生器106和它的短码PN发生器108和110(如图9所示)。这里还详细描述从属基站64的搜索器处理。
图7示出从属基站64的装置。在从属基站64中,接收来自基站控制器60的表示移动站60的PN的信号。向控制处理器100提供该消息。响应于此,控制处理器100计算以特定PN偏置为中心的窗口搜索范围。控制处理器100向搜索器101提供搜索参数,并响应于那些参数,从属基站64指挥对由移动站60发送的信号的搜索。向接收机104提供由从属基站64的天线102接收的信号,其中上述接收机104下变频、滤波和放大接收信号并向搜索器101提供它。此外,向话务解调器105提供接收信号,它解调反向链路话物数据,而且向基站控制器60提供该数据。基站控制器66反过来向公共电话交换网提供它。
图9详细示出搜索器101。在待批美国专利申请第08/372,632号(1995年1月3日申请,发明名称为“用于扩展频谱多址通信系统的区站解调器体系结构”)和待批美国专利申请第08/316,177号(1994年9月30日申请,发明名称为“用于扩展频谱多址通信系统的多路径搜索处理器”)中详细描述对反向链路信号的解调,其中上述两项专利已转让给本发明的受让人,并作为参考资料在此引入。从基站控制器66向控制处理器100提供移动站60的PN偏置的估计。响应于由基站控制器60提供的PN偏置估计,控制处理器100产生初始长PN序列假设,以及初始短PN序列假设,用于由从属基站64执行搜索。在示例实施例中,控制处理器100组装载PN发生器106、108和110的移位寄存器。
由天线102接收信号,下变频、滤波和放大并将它通到相关器116。相关器116使接收到信号与组合长和短PN序列假设相关联。在示例实施例中,通过将由PN发生器108和110产生的短PN假设与由PN发生器106产生的长PN序列相乘,产生短PN假设。用组合的PN序列假设之一来去扩展I信道,用另一个来去扩展接收QPSK信号的Q信道。
向快速Hadamard变换(FHT)处理器118和120提供两个PN去扩展信号。在待批美国专利申请第08/173,460号(1993年12月22日申请,发明名称是“用于执行快速Hadadmard变换的方法和装置”,已转让给本发明的受让人,并作为参考资料在此引入。FHT处理器118和120使去扩展信号与所有可行Walsh码元相关联,来向能量计算装置(I2+Q2)122提供所得幅度矩阵。能量计算装置122计算幅度矩阵元素的能量,并向选择最大能量相关性的最大检测器124提供能量值。向对于多个Walsh码元累加能量的累加器126提供最大相关性能量,并根据这些累加能量,确定是否可在该PN偏置处捕获移动站60。
IV.由从属基站调节初始定时
一旦捕获移动站60,那么在框306中,从属基站64调节它的定时,从而移动站60能够成功地捕获它的前向链路传输。从属基站64通过确定捕获来自移动站60的反向链路信号的PN偏置和参考基站62用于接收来自移动站60的反向链路信号的PN偏置之差。运用该PN偏置差,从属基站64以当移动站60搜索它的导频信号时它将落在移动站60的搜索窗口内的方式,调节它的导频信号的定时。
V.由移动站捕获从属基站
在搜索移动站信号的过程中,从属基站64需要具有一些时间的指示。在较佳实施例中,通过另一种同步方案,将从属基站64的时间误差保持在或低于1毫秒。存在使不能接收GPS信号的从属基站64保持精度较低的时间的方案。获得初始同步程度的一种可行的方法是将从属基站64的时间人工设定在某一间隔。第二种方法是运用WWV接收机设定时间,其实施方法在现有技术中已知。与GPS信号不同,在很低的频率下发送WWV集中定时信号,而且能够透入(penetrate into)隧道和地铁。然而,WWV接收机不能提供进行CDMA通信所需的时间同步程度。
在示例实施例中,从属基站64根据移动站60直接位于从属基站64附近的假设,调节它的定时。于是,在从属基站64和移动站60之间没有任何传播延长的假设下,进行初始定时调节。此后,从属基站64事先(forward in time)调节它的PN序列发生器72和74,这解释在从属基站64和移动站60之间的越来越大的传播延长时间。一旦移动站60捕获从属基站64的导频信道,运用正常程序,根据上述计算可以执行对于从属基站64的最终定时调节。
如在现有技术中已知并在标准IS-95中标准化,通过它们的PN发生器的相位,将不同基站的导频信道相互区分开来。参考基站62指示移动站60通过邻近组列表搜寻从属基站64参考基站62指示利用从属基站64的导频可在PN相位偏置处捕获的信令数据,其中相对参考基站62的接收PN偏置描述了PN相位偏置。由话务解调器54解调和解码该消息,而且向搜索器50提供。作为响应,搜索器50执行集中于围绕PN相位的PN相位偏置的搜索,其中在来自参考基站62的信号中指定了上述PN相位。
一般,由线性反馈移位寄存器产生导频信号,在上述专利中详细描述了它的实施情况。为了捕获来自从属基站64的导频信号,移动站60必须在相位φ和频率ω与来自从属基站64的接收信号同步。搜索器操作的目的在于找到接收信号的相位φ。如前面所述,可以利用来自基站控制器66的T1链路,向从属基站64提供相对精确的频率同步,如在现有技术中已知的那样。移动站找到接收信号的相位的方法是通过测试一组相位假设,称为搜索窗口,并确定偏置假设之一是否正确。
图5详细示出移动站搜索器50。在天线2处接收扩展频谱信号。装置的目的在于在由PN序列发生器20产生伪随机噪声(PN)序列和由从属基站64发送的未知相位的同一PN序列扩展的接收扩展频谱之间的获得同步。在示例实施例中,导频信号发生器76(图7)和PN发生器20是最大长度移位寄存器,它们产生分别用于扩展和去扩展导频信号的PN码序列。于是,在用于去扩展接收导频信号的代码和接收导频信号的PN扩展码之间捕获同步的操作包括确定移位寄存器的时间偏置。
由天线2向接收机4提供扩展频谱信号。接收机4下变频、滤波和放大信号并向去扩展元件6提供该信号。去扩展元件6把接收信号与由PN发生器20产生的PN码相乘。由于PN码的类似于随机噪声的本质,PN码和接收信号乘积实质上应为零,除了接近同步的时刻。
搜索控制器18向PN发生器20提供偏置假设。根据由参考基站62向移动站60发送的信号,确定偏置假设。在示例实施例中,通过四相移相键控(QPSK)调制接收信号,所以PN发生器20向去扩展元件6提供用于I调制分量的PN序列和用于Q调制元件的分开序列。去扩展元件6把PN序列与它的相应调制分量相乘,而且向相干累加器8和10提供两个输出分量乘积。
相干累加器8和10总加超出乘积序列的长度的乘积。相干累加器8和10响应于来自搜索器控制器18的信号,用于重新设定、锁定和设定加法周期。从加法器8和10向平方装置14提供乘积之和。平方装置14对每个总和求平方,而且把平方值相加。
由平方装置12向非相干组合器14提供平方总和。非相干组合器14确定来自平方装置12的输出的能量值。非相干累加器14用于抵销在基站发送时钟和移动站接收时钟之间的频率差的效应,而且有助于在衰落环境中的检测统计。非相干累加器14向比较装置16提供能量信号。比较装置16把能量值和由搜索器控制器装置18提供的预定门限相比较。于是,把每次比较的结果反馈给搜索器控制器18。反馈到搜索器控制器18的结果包括相关性的能量和在测量中所致的PN偏置。
在本发明中,搜索器控制器18输出PN相位,在该相位处将它与基站64同步。将该偏置用于计算时间误差,如下面进一步所述。
在示例实施例中,当移动站60捕获从属基站64时,它计算在它接收来自从属基站64的信号的时间和它接收来自参考基站62的信号的时间之差。向产生表示该差值的消息的消息发生器52提供该值。在反向链路上,把该消息作为信令数据发送到参考基站62和从属基站64,它们把消息反送回到基站控制器66。
VI.测量从从属基站传输前向链路信号和在从属基站接收反向链路信号之间的延迟
在步骤311中,从属基站64测量它接收来自移动站60的反向链路信号的时间(T2)和它把前向链路信号发送到移动站60的时间(T1)之差。从属基站64在它发送它的前向链路信号的时刻存储PN偏置,而且一旦检测来自移动站60的反向链路信号,就计算时差RTD2。在示例实施例中,由从属基站64向基站控制器66提供该经计算时差,而且在基站66处执行对定时计算的调节。熟悉该技术领域的人员应理解,本发明易于扩展到在基站或移动站处执行计算的情况。
VII.从属基站的定时调节
基站控制器66作为响应,执行在等式(12)中描述的计算,而且把对所需定时调节的指示发送到从属基站64。参照图7,由从属基站64在控制处理器100处接收定时调节信号。控制处理器100产生和向定时调节处理器99提供控制信号。定时调节处理器99产生信号,它用来自基站控制器66的信号所示的量。改变定时源98的时间。
Claims (1)
1.一种用于将第一基站与参考基站时间同步的方法,其特征在于,包括步骤:
测量从所述参考基站到与所述参考基站进行通信的移动站和从所述移动站回到所述参考基站的传输的往返行程延迟间隔;
在所述移动站处测量接收来自所述第一基站的前向链路信号的时间和接收来自所述参考基站的前向链路信号的时间之间的第一时差;
在所述第一基站处测量接收来自所述移动站的反向链路信号的时间和从所述第一基站发送前向链路信号的时间之间的第二时差;和
根据所述测得的往返行程延迟间隔、所述第一时差和所述第二时差按照下式计算定时校正值:
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