CN114567923A - Uplink synchronization method in satellite communication system - Google Patents

Uplink synchronization method in satellite communication system Download PDF

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CN114567923A
CN114567923A CN202011351914.4A CN202011351914A CN114567923A CN 114567923 A CN114567923 A CN 114567923A CN 202011351914 A CN202011351914 A CN 202011351914A CN 114567923 A CN114567923 A CN 114567923A
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terminal
base station
time
downlink frame
transmission delay
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张俊
庆兴发
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Beijing Commsat Technology Development Co Ltd
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W56/00Synchronisation arrangements
    • H04W56/0005Synchronisation arrangements synchronizing of arrival of multiple uplinks
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W56/00Synchronisation arrangements
    • H04W56/004Synchronisation arrangements compensating for timing error of reception due to propagation delay
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W84/00Network topologies
    • H04W84/02Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/04Large scale networks; Deep hierarchical networks
    • H04W84/06Airborne or Satellite Networks
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02DCLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00Reducing energy consumption in communication networks
    • Y02D30/70Reducing energy consumption in communication networks in wireless communication networks

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Abstract

本发明提出一种卫星通信系统中的上行同步方法,包括:基站和终端与同一授时系统保持时间同步,通过相同的规则映射出下行帧基准时刻;终端自行测量下行帧到达时刻与所述基准时刻的偏差,作为基站到终端的单向传输时延;终端根据所述单向传输时延提前发送上行信号,以使所述上行信号在期望接收时间窗内到达基站侧。本申请不依赖任何星历和地理位置信息就能完成基站到终端的传输时延测量,避免基站位置更新导致的空口开销和终端复杂处理;对于透明转发处理方式的基站,终端无需区别处理,简化终端操作;准确的终端上行时延预补偿机制,可大幅减少RACH接收窗长度,从而减少上行开销,缩短接入时延。

Figure 202011351914

The present invention provides an uplink synchronization method in a satellite communication system, which includes: a base station and a terminal maintain time synchronization with the same timing system, and map a downlink frame reference time through the same rules; the terminal measures the arrival time of the downlink frame and the reference time by itself The deviation is taken as the one-way transmission delay from the base station to the terminal; the terminal sends the uplink signal in advance according to the one-way transmission delay, so that the uplink signal reaches the base station side within the expected receiving time window. This application can complete the transmission delay measurement from the base station to the terminal without relying on any ephemeris and geographic location information, avoiding the air interface overhead caused by the location update of the base station and the complex processing of the terminal; for the base station in the transparent forwarding processing mode, the terminal does not need to be processed differently, simplifying Terminal operation; accurate terminal uplink delay pre-compensation mechanism can greatly reduce the length of the RACH receiving window, thereby reducing uplink overhead and shortening access delay.

Figure 202011351914

Description

一种卫星通信系统中的上行同步方法A kind of uplink synchronization method in satellite communication system

技术领域technical field

本发明涉及卫星通信领域,尤其涉及一种卫星通信系统中的上行同步方法。The invention relates to the field of satellite communication, in particular to an uplink synchronization method in a satellite communication system.

背景技术Background technique

卫星通信系统的一个关键问题是上行同步,卫星通信上行同步是指终端调整信号发送时间,使得信号在指定时刻到达星上基站,一般步骤包括:地面终端发出随机接入的RACH信号;星上基站通过检测RACH信号到达的时间,测算出终端到基站的信号传输时延;基站通过下发定时调整TA命令给终端;终端调整信号发送时刻,使得信号在指定时间点到达星上基站。A key issue of satellite communication system is uplink synchronization. Uplink synchronization of satellite communication means that the terminal adjusts the signal transmission time so that the signal arrives at the satellite base station at the specified time. The general steps include: the ground terminal sends a random access RACH signal; the satellite base station By detecting the arrival time of the RACH signal, the signal transmission delay from the terminal to the base station is measured; the base station adjusts the TA command to the terminal by issuing timing; the terminal adjusts the signal transmission time so that the signal arrives at the satellite base station at the specified time point.

如果按照地面5G的方案,RACH信号检测窗时长需为基站覆盖距离的2倍除以光速,如小区覆盖距离为600km,则RACH窗长则为4ms以上,这将导致很大的时域开销。为了降低这一开销,业界提出了两种方法。According to the terrestrial 5G scheme, the RACH signal detection window length needs to be 2 times the coverage distance of the base station divided by the speed of light. For example, if the cell coverage distance is 600km, the RACH window length is more than 4ms, which will result in a large time domain overhead. To reduce this overhead, the industry has proposed two methods.

一种方法称为闭环方法,由卫星根据其轨道高度及覆盖区域,把覆盖区域边缘的发送信号提前量广播给终端,终端根据该信息先调整RACH发送时刻,此时RACH窗长可配置为2*(D2-D1)/C;其中D2是星上基站和覆盖范围内终端的最远距离,D1是星上基站和覆盖范围内终端的最近距离,如图1所示。以600km轨高,小区直径400km测算,RACH时长约0.8ms。该闭环方案的RACH窗较大,系统开销较大。One method is called a closed-loop method. The satellite broadcasts the advance of the transmitted signal at the edge of the coverage area to the terminal according to its orbit height and coverage area. The terminal first adjusts the RACH transmission time according to the information, and the RACH window length can be configured to 2 *(D2-D1)/C; where D2 is the farthest distance between the on-board base station and the terminal within the coverage area, and D1 is the shortest distance between the on-board base station and the terminal within the coverage area, as shown in Figure 1. Calculated with a track height of 600km and a cell diameter of 400km, the RACH duration is about 0.8ms. The closed-loop scheme has a larger RACH window and a larger system overhead.

另一种方法称为开环方法,由终端根据自身位置信息和星历信息,测算出终端和星上基站间的距离,从而提前调整RACH发送时刻,此时RACH的窗长可以配置为更短。这种开环方案的RACH窗较小,开销也较小,但依赖于终端定位,星历信息。对于星上透明转发处理模式,终端需获取地面基站位置信息,星历信息,需要星历和地理位置信息的误差控制在较小范围,而地面基站建设频繁,终端初始信息也需频繁更新,维护代价很高。Another method is called the open-loop method. The terminal calculates the distance between the terminal and the base station on the satellite according to its own location information and ephemeris information, so as to adjust the RACH transmission time in advance. At this time, the window length of the RACH can be configured to be shorter. . This open-loop scheme has a smaller RACH window and lower overhead, but it depends on terminal positioning and ephemeris information. For the on-satellite transparent forwarding processing mode, the terminal needs to obtain the location information and ephemeris information of the ground base station, and the error of the ephemeris and geographical position information needs to be controlled in a small range, and the ground base station is constructed frequently, and the initial information of the terminal also needs to be updated frequently. Maintenance The price is high.

发明内容SUMMARY OF THE INVENTION

针对上述问题,本申请提出一种卫星通信系统中的上行同步方法,包括:基站和终端与同一授时系统保持时间同步,通过相同的规则映射出下行帧基准时刻;终端自行测量下行帧到达时刻与所述基准时刻的偏差,作为基站到终端的单向传输时延;终端根据所述单向传输时延提前发送上行信号,以使所述上行信号在期望接收时间窗内到达基站侧。In view of the above problems, the present application proposes an uplink synchronization method in a satellite communication system, including: the base station and the terminal maintain time synchronization with the same timing system, and map the reference time of the downlink frame through the same rules; the terminal measures the arrival time of the downlink frame by itself. The deviation of the reference time is used as the one-way transmission delay from the base station to the terminal; the terminal sends the uplink signal in advance according to the one-way transmission delay, so that the uplink signal reaches the base station side within the expected receiving time window.

进一步的,所述终端自行测量下行帧到达时刻与所述基准时刻的偏差,具体包括:终端检测基站在T1时刻发送的下行帧,记录检测到该下行帧的时刻为T2,计算二者偏差作为所述单向传输时延D=T2-T1。Further, the terminal measures the deviation between the arrival time of the downlink frame and the reference time by itself, which specifically includes: the terminal detects the downlink frame sent by the base station at time T1, records the time when the downlink frame is detected as T2, and calculates the difference between the two as T2. The one-way transmission delay D=T2-T1.

更进一步的,所述终端根据所述单向传输时延,提前发送上行信号,以使所述上行信号在期望接收时间窗内到达基站侧,包括:终端以期望接收时刻T3为基准,提前一个传输时延D发送上行信号,以使所述上行信号在起始位置早于T3、结束位置大于T3+Further, the terminal sends the uplink signal in advance according to the one-way transmission delay, so that the uplink signal reaches the base station side within the expected receiving time window, including: the terminal takes the expected receiving time T3 as a reference, and sends the uplink signal one time earlier. The transmission delay D sends the uplink signal, so that the start position of the uplink signal is earlier than T3 and the end position is greater than T3+

T_duration的期望接收时间窗口到达基站侧;其中,所述T_duration为所述上行信号的持续时长。The expected receiving time window of T_duration arrives at the base station side; wherein, the T_duration is the duration of the uplink signal.

更进一步的,所述期望接收时刻T3由基站侧通过广播信息以明示信息或暗示信息下发,或者由终端和基站各自根据本地时间和所述相同的规则各自计算得出。Further, the expected reception time T3 is issued by the base station side through broadcast information as explicit information or implied information, or calculated by the terminal and the base station according to the local time and the same rule.

更进一步的,所述T1、T2和T3为相对时间、绝对时间或者某帧号内的某时隙。Further, the T1, T2 and T3 are relative time, absolute time or a certain time slot within a certain frame number.

进一步的,所述基站和终端与同一授时系统保持时间同步,通过相同的规则映射出下行帧基准时刻,包括:基站和终端均与GNSS或1588V2同步,获取1PPS授时;基站和终端均基于1PPS信息生成帧边界定时,并依次分配帧号。Further, the base station and the terminal maintain time synchronization with the same timing system, and map the downlink frame reference time through the same rules, including: the base station and the terminal are synchronized with GNSS or 1588V2 to obtain 1PPS timing; both the base station and the terminal are based on 1PPS information. Frame boundary timing is generated, and frame numbers are assigned in sequence.

更进一步的,所述终端自行测量下行帧到达时刻和所述基准时刻的偏差,作为基站到终端的单向传输时延;包括:终端检测到下行帧,记录检测到该下行帧的时刻Trev;计算该时刻与本地基准定时对应的最新下行帧的边界时刻Tbase之差,Td=Trev-Tbase;计算该下行帧广播信道中携带的帧号与本地基准定时对应的最新下行帧的帧号之差N,计算所述单向传输时延D=Td+N*帧长。Further, the terminal measures the deviation between the arrival time of the downlink frame and the reference time by itself, as the one-way transmission delay from the base station to the terminal; including: the terminal detects the downlink frame, and records the time Trev when the downlink frame is detected; Calculate the difference between the boundary time Tbase of the latest downlink frame corresponding to this moment and the local reference timing, Td=Trev-Tbase; calculate the difference between the frame number carried in the broadcast channel of this downlink frame and the frame number of the latest downlink frame corresponding to the local reference timing N, calculate the one-way transmission delay D=Td+N*frame length.

更进一步的,所述终端自行测量下行帧到达时刻和所述基准时刻的偏差,作为基站到终端的单向传输时延;包括:终端检测到下行帧,记录检测到该下行帧的时刻Trev;计算该时刻与本地基准定时对应的最新下行帧的边界时刻Tbase之差,Td=Trev-Tbase;比较该下行帧广播信道中携带的帧号和本地基准定时对应的最新下行帧的帧号的奇偶属性:如果二者奇偶属性相同,则所述单向传输时延D=Td;如果二者奇偶属性不同,则所述单向传输时延D=Td+帧长。Further, the terminal measures the deviation between the arrival time of the downlink frame and the reference time by itself, as the one-way transmission delay from the base station to the terminal; including: the terminal detects the downlink frame, and records the time Trev when the downlink frame is detected; Calculate the difference between this moment and the boundary moment Tbase of the latest downlink frame corresponding to the local reference timing, Td=Trev-Tbase; compare the frame number carried in the broadcast channel of the downlink frame and the parity of the frame number of the latest downlink frame corresponding to the local reference timing Attribute: if the parity attributes of the two are the same, the one-way transmission delay D=Td; if the parity attributes of the two are different, the one-way transmission delay D=Td+frame length.

更进一步的,所述终端根据所述单向传输时延提前发送上行信号,以使所述上行信号在期望接收时间窗内到达基站侧,包括:终端以所述Trev为基准,提前2个所述单向传输时延2*D发送上行信号。Further, the terminal sends the uplink signal in advance according to the one-way transmission delay, so that the uplink signal arrives at the base station side within the expected reception time window, including: the terminal uses the Trev as a reference, and sends the uplink signal two times in advance. Send the uplink signal with the one-way transmission delay 2*D.

进一步的,所述基站为星上基站或地面基站或星上基站和地面基站。Further, the base station is an on-board base station or a ground base station or an on-board base station and a ground base station.

本发明不依赖任何星历和地理位置信息就能完成基站到终端的传输时延测量,避免基站位置更新的导致的空口开销和终端复杂处理;对于透明转发处理方式的基站,终端无需区别处理,简化终端操作;准确的终端上行时延预补偿机制,可大幅减少RACH接收窗长度,从而减少上行开销,缩短接入时延。The invention can complete the transmission delay measurement from the base station to the terminal without relying on any ephemeris and geographical position information, and avoid the air interface overhead caused by the location update of the base station and the complex processing of the terminal; Simplified terminal operation; accurate terminal uplink delay pre-compensation mechanism can greatly reduce the length of the RACH receiving window, thereby reducing uplink overhead and shortening access delay.

附图说明Description of drawings

为了更清楚地说明本发明实施例或现有技术中的技术方案,下面将对实施例或现有技术描述中所需要使用的附图作一简单地介绍,显而易见地,下面描述中的附图是本发明的一些实施例,对于本领域普通技术人员来讲,在不付出创造性劳动的前提下,还可以根据这些附图获得其他的附图。In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

图1为现有技术中卫星广播覆盖区域边缘的发送信号提前量示意图;1 is a schematic diagram of the advance amount of the transmitted signal at the edge of the satellite broadcasting coverage area in the prior art;

图2为本申请实施例1提出的上行同步示意图;FIG. 2 is a schematic diagram of uplink synchronization proposed in Embodiment 1 of the present application;

图3为本申请实施例2提出的上行同步示意图;3 is a schematic diagram of uplink synchronization proposed in Embodiment 2 of the present application;

图4为本申请实施例3提出的上行同步示意图。FIG. 4 is a schematic diagram of uplink synchronization proposed in Embodiment 3 of the present application.

具体实施方式Detailed ways

为使本发明实施例的目的、技术方案和优点更加清楚,下面将结合本发明实施例中的附图,对本发明实施例中的技术方案进行清楚、完整地描述,显然,所描述的实施例是本发明一部分实施例,而不是全部的实施例;需要说明的是,在不冲突的情况下,本申请中的实施例及实施例中的特征可以相互组合。基于本发明中的实施例,本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例,都属于本发明保护的范围。In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of the embodiments of the present invention, but not all of the embodiments; it should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other under the condition of no conflict. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

本申请的一个实施例提出一种卫星通信系统中的上行同步方法,包括:基站和终端与同一授时系统保持时间同步,通过相同的规则映射出下行帧基准时刻;终端自行测量下行帧到达时刻与基准时刻的偏差,作为基站到终端的单向传输时延;终端根据单向传输时延提前发送上行信号,以使上行信号在期望接收时间窗内到达基站侧。An embodiment of the present application proposes an uplink synchronization method in a satellite communication system, including: the base station and the terminal maintain time synchronization with the same timing system, and map the reference time of the downlink frame through the same rule; the terminal measures the arrival time of the downlink frame by itself. The deviation of the reference time is regarded as the one-way transmission delay from the base station to the terminal; the terminal sends the uplink signal in advance according to the one-way transmission delay, so that the uplink signal reaches the base station side within the expected receiving time window.

在一个可选实施例中,包括:终端检测基站在T1时刻发送的下行帧,记录检测到该下行帧的时刻为T2,计算二者偏差作为所述单向传输时延D=T2-T1;终端以期望接收时刻T3为基准,提前一个传输时延D发送上行信号,以使上行信号在起始位置早于T3、结束位置大于T3+T_duration的期望接收时间窗口到达基站侧;其中,T_duration为上行信号的持续时长。其中期望接收时刻T3可以由基站侧通过广播信息以明示信息或暗示信息下发,也可以由终端和基站各自根据本地时间和相同的规则各自计算得出。T1、T2和T3可以是相对时间、绝对时间,也可以是某一帧号内的某个时隙。In an optional embodiment, it includes: the terminal detects the downlink frame sent by the base station at time T1, records the time when the downlink frame is detected as T2, and calculates the difference between the two as the one-way transmission delay D=T2-T1; Based on the expected receiving time T3, the terminal sends the uplink signal with a transmission delay D in advance, so that the uplink signal reaches the base station side in the expected receiving time window whose starting position is earlier than T3 and the ending position is greater than T3+T_duration; among them, T_duration is The duration of the upstream signal. The expected receiving time T3 may be issued by the base station side as explicit information or implied information through broadcast information, or may be calculated by the terminal and the base station according to local time and the same rules. T1, T2 and T3 can be relative time, absolute time, or a certain time slot in a certain frame number.

实施例1Example 1

本实施例中,基站和终端均与全球导航卫星系统GNSS同步,以同一个参考时间点作为帧起始时刻T1,基站在参考时间点发送下行同步信号。终端接收到下行同步信号后,通过计算下行同步信号的到达时间T2与参考时间点T1的时间差T_offset=T2-T1,获得地面基站或星上基站到终端的传输时延。终端根据基站接收时刻要求,提前T_offset进行发送,满足信号在指定时刻T3到达基站,基站可以在较小的检测窗内完成信号接收,请参考图2。主要步骤包括:In this embodiment, both the base station and the terminal are synchronized with the global navigation satellite system GNSS, and the same reference time point is used as the frame start time T1, and the base station sends the downlink synchronization signal at the reference time point. After receiving the downlink synchronization signal, the terminal calculates the time difference T_offset=T2-T1 between the arrival time T2 of the downlink synchronization signal and the reference time point T1 to obtain the transmission delay from the ground base station or the satellite base station to the terminal. According to the receiving time requirement of the base station, the terminal sends T_offset in advance, so that the signal arrives at the base station at the specified time T3, and the base station can complete the signal reception within a small detection window, please refer to Figure 2. The main steps include:

步骤1、基站和终端均通过GPS,BD等GNSS系统获取UTC时间和1PPS信息,参考时间点T1,T2,T3可由UTC时间定义,可以是相对时间,绝对时间,某SFN号帧内的某个slot;Step 1. Both the base station and the terminal obtain UTC time and 1PPS information through GPS, BD and other GNSS systems. The reference time points T1, T2, and T3 can be defined by UTC time, which can be relative time, absolute time, or a certain time in a certain SFN frame. slot;

步骤2、基站在T1时刻下发同步及广播信号,其中广播信息中的帧号可由T1计算得到;Step 2, the base station sends synchronization and broadcast signals at time T1, wherein the frame number in the broadcast information can be calculated by T1;

步骤3、终端在检测到下行同步信号后,获取此时的时间T2,并计算T_offset,取值为T2-T1,即基站到终端间的传输时延;Step 3. After the terminal detects the downlink synchronization signal, it obtains the time T2 at this time, and calculates T_offset, and the value is T2-T1, that is, the transmission delay between the base station and the terminal;

步骤4、终端在下行广播信号中获取基站期望接收到上行信号的时间T3,提前T_offset发送上行信号,信号持续时长为T_duration;Step 4. The terminal obtains the time T3 when the base station expects to receive the uplink signal in the downlink broadcast signal, and sends the uplink signal in advance by T_offset, and the signal duration is T_duration;

步骤5、基站的接收窗起始位置稍早于T3,接收窗的结束位置可略大于T3+T_duration,确保上行信号落在接收窗内。Step 5: The starting position of the receiving window of the base station is slightly earlier than T3, and the ending position of the receiving window may be slightly greater than T3+T_duration, to ensure that the uplink signal falls within the receiving window.

在一个可选实施例中,基站和终端均与GNSS或1588V2同步,获取1PPS授时;基于1PPS信息生成帧边界定时,并依次分配帧号。In an optional embodiment, both the base station and the terminal are synchronized with GNSS or 1588V2 to obtain 1PPS timing; frame boundary timing is generated based on the 1PPS information, and frame numbers are assigned in sequence.

在一个可选实施例中,终端检测到下行帧,记录检测到该下行帧的时刻Trev;计算该时刻与本地基准定时对应的最新下行帧的边界时刻Tbase之差,Td=Trev-Tbase;计算该下行帧广播信道中携带的帧号与本地基准定时对应的最新下行帧的帧号之差N,计算所述单向传输时延D=Td+N*帧长。In an optional embodiment, the terminal detects a downlink frame, and records the time Trev at which the downlink frame is detected; calculates the difference between the time and the boundary time Tbase of the latest downlink frame corresponding to the local reference timing, Td=Trev-Tbase; calculates The difference N between the frame number carried in the downlink frame broadcast channel and the frame number of the latest downlink frame corresponding to the local reference timing is calculated to calculate the one-way transmission delay D=Td+N*frame length.

在一个可选实施例中,终端检测到下行帧,记录检测到该下行帧的时刻Trev;计算该时刻与本地基准定时对应的最新下行帧的边界时刻Tbase之差,Td=Trev-Tbase;比较该下行帧广播信道中携带的帧号和本地基准定时对应的最新下行帧的帧号的奇偶属性:如果二者奇偶属性相同,则单向传输时延D=Td;如果二者奇偶属性不同,则所述单向传输时延D=Td+帧长。In an optional embodiment, the terminal detects a downlink frame, and records the time Trev at which the downlink frame is detected; calculates the difference between the time and the boundary time Tbase of the latest downlink frame corresponding to the local reference timing, Td=Trev-Tbase; compares The parity attribute of the frame number carried in the broadcast channel of the downlink frame and the frame number of the latest downlink frame corresponding to the local reference timing: if the parity attributes of the two are the same, the one-way transmission delay D=Td; if the parity attributes of the two are different, Then the one-way transmission delay D=Td+frame length.

在一个可选实施例中,终端以Trev为基准提前2个单向传输时延发送上行信号。In an optional embodiment, the terminal sends the uplink signal in advance of two one-way transmission delays based on Trev.

在一个可选实施例中,基站为星上基站或地面基站或星上基站和地面基站。In an optional embodiment, the base station is an on-board base station or a terrestrial base station or an on-board base station and a terrestrial base station.

实施例2:星上处理基站的上行同步方法Embodiment 2: On-board processing base station uplink synchronization method

本实施例提出的同步方法示意图请参考图3。包括如下步骤:Please refer to FIG. 3 for a schematic diagram of the synchronization method proposed in this embodiment. It includes the following steps:

基站和终端均与GNSS同步,获取1PPS授时,授时精度一般可满足1us偏差;Both the base station and the terminal are synchronized with GNSS to obtain 1PPS timing, and the timing accuracy can generally meet the 1us deviation;

基站和终端均基于1PPS信息生成10ms帧边界定时:Both the base station and the terminal generate 10ms frame boundary timing based on 1PPS information:

基站为1PPS定时后的第一个10ms无线帧分配偶数帧号,第二个10ms无线帧分配奇数帧号,后续各帧依次累加帧号,帧号范围为0~1023,累加到达1023后,需重新从0开始编号;The base station assigns odd-numbered frame numbers to the first 10ms wireless frame after 1PPS timing, and assigns odd-numbered frame numbers to the second 10ms wireless frame. The frame numbers are sequentially accumulated for each subsequent frame. The frame number ranges from 0 to 1023. Restart numbering from 0;

终端基准定时系统默认1PPS后的第一个10ms无线帧为偶数帧,后续偶数帧和奇数帧交替出现。The terminal reference timing system defaults that the first 10ms radio frame after 1PPS is an even frame, and subsequent even frames and odd frames appear alternately.

终端检测到SFN号为X的下行帧后,首先记录检测到的X无线帧起始时刻Trev_X,然后获取本地存储最新的10ms帧边界时刻Tbase_X和10ms帧的奇偶帧属性,定义TDelay_X=Trev_X-Tbase_X,单位为us。After the terminal detects the downlink frame with the SFN number X, it first records the detected start time Trev_X of the X radio frame, and then obtains the latest 10ms frame boundary time Tbase_X and the parity frame attributes of the 10ms frame stored locally, and defines TDelay_X=Trev_X-Tbase_X , the unit is us.

如果终端检测到的无线帧编号X与终端基准定时对应的最新10ms帧的奇偶属性相同,即同为奇数或同为偶数,则基准到终端的传输时延TDelay=TDelay_X;如果终端检测到的无线帧编号X与终端基准定时对应的最新10ms帧的奇偶属性不同,则基准到终端的传输时延TDelay=TDelay_X+10000,单位为us。If the wireless frame number X detected by the terminal is the same as the parity attribute of the latest 10ms frame corresponding to the reference timing of the terminal, that is, both are odd or even, then the transmission delay from the reference to the terminal TDelay=TDelay_X; The frame number X is different from the parity attribute of the latest 10ms frame corresponding to the reference timing of the terminal, so the transmission delay from the reference to the terminal TDelay=TDelay_X+10000, and the unit is us.

终端以Trev_X为基准,提前2*TDelay进行发送,补偿下行传输时延,保证星下所有终端信号的上行信号到达星上基站时实现微秒级粗同步。Based on Trev_X, the terminal sends 2*TDelay in advance to compensate for the downlink transmission delay and ensure that the uplink signals of all terminal signals under the satellite reach the base station on the satellite to achieve microsecond-level coarse synchronization.

实施例3:透明转发基站的上行同步方法Embodiment 3: Uplink synchronization method of transparent forwarding base station

请参考图4,本实施例中星上部分仅作数据的透明转发。此时的上行同步主要包括如下步骤:Referring to FIG. 4 , in this embodiment, the on-board part is only used for transparent data forwarding. The uplink synchronization at this time mainly includes the following steps:

地面基站和终端均与GNSS或1588V2同步,获取1PPS授时,星上透明转发单元无需与GNSS同步。Both the ground base station and the terminal are synchronized with GNSS or 1588V2 to obtain 1PPS timing, and the on-board transparent forwarding unit does not need to be synchronized with GNSS.

地面基站和终端均基于1PPS信息生成10ms帧边界定时:地面基站为1PPS定时后的第一个10ms无线帧分配偶数帧号,第二个10ms无线帧分配奇数帧号,后续各帧依次累加帧号,帧号范围为0~1023,累加到达1023后,需重新从0开始编号;终端基准定时系统默认1PPS后的第一个10ms无线帧为偶数帧,后续偶数帧和奇数帧交替出现。Both the ground base station and the terminal generate 10ms frame boundary timing based on 1PPS information: the ground base station assigns odd-numbered frame numbers to the first 10ms radio frame after 1PPS timing, and assigns odd-numbered frame numbers to the second 10ms radio frame, and successively accumulates frame numbers for each subsequent frame. , the frame number ranges from 0 to 1023. After the accumulation reaches 1023, the numbering needs to start from 0 again; the terminal reference timing system defaults to the first 10ms wireless frame after 1PPS as an even frame, and subsequent even and odd frames appear alternately.

终端检测到SFN号为X的下行帧后,首先记录检测到的X无线帧起始时刻Trev_X,然后获取本地存储最新的10ms帧边界时刻Tbase_X和10ms帧的奇偶帧属性,定义TDelay_X=Trev_X-Tbase_X。After the terminal detects the downlink frame with the SFN number X, it first records the detected start time Trev_X of the X radio frame, and then obtains the latest 10ms frame boundary time Tbase_X and the parity frame attributes of the 10ms frame stored locally, and defines TDelay_X=Trev_X-Tbase_X .

如果终端检测到的无线帧编号X与终端基准定时对应的最新10ms帧的奇偶属性相同,则基站到终端的传输时延TDelay=TDelay_X;如果终端检测到的无线帧编号X与终端基准定时对应的最新10ms帧的奇偶属性不同,则基准到终端的传输时延TDelay=TDelay_X+10000。If the radio frame number X detected by the terminal is the same as the parity attribute of the latest 10ms frame corresponding to the terminal reference timing, then the transmission delay from the base station to the terminal TDelay=TDelay_X; if the radio frame number X detected by the terminal corresponds to the terminal reference timing If the parity attributes of the latest 10ms frame are different, the transmission delay from the reference to the terminal TDelay=TDelay_X+10000.

终端以Trev_X为基准,提前2*TDelay进行发送,补偿下行传输时延,保证星下所有终端信号的上行信号到达星上基站时实现微秒级粗同步。Based on Trev_X, the terminal sends 2*TDelay in advance to compensate for the downlink transmission delay and ensure that the uplink signals of all terminal signals under the satellite reach the base station on the satellite to achieve microsecond-level coarse synchronization.

以上两个实施例最大可检测20ms的传输时延,在地面基站与终端的总距离小于6000km时可准确测量传输时延。The above two embodiments can detect the maximum transmission delay of 20ms, and can accurately measure the transmission delay when the total distance between the ground base station and the terminal is less than 6000km.

通过上述各实施例可以看出,本申请可以不依赖任何星历和地理位置信息就能完成基站到终端的传输时延测量,避免基站位置更新导致的空口开销和终端复杂处理;对于透明转发处理方式的基站,终端无需区别处理,简化终端操作;准确的终端上行时延预补偿机制,可大幅减少RACH接收窗长度,从而减少上行开销,缩短接入时延。It can be seen from the above embodiments that the present application can complete the transmission delay measurement from the base station to the terminal without relying on any ephemeris and geographic location information, avoiding the overhead of the air interface and the complex processing of the terminal caused by the location update of the base station; for transparent forwarding processing The base station of the method, the terminal does not need to be processed differently, which simplifies the terminal operation; the accurate terminal uplink delay pre-compensation mechanism can greatly reduce the length of the RACH receiving window, thereby reducing the uplink overhead and shortening the access delay.

本领域普通技术人员可以理解:实现上述方法实施例的全部或部分步骤可以通过程序指令相关的硬件来完成,前述的程序可以存储于一计算机可读取存储介质中,该程序在执行时,执行包括上述方法实施例的步骤;而前述的存储介质包括:ROM、RAM、磁碟或者光盘等各种可以存储程序代码的介质。Those of ordinary skill in the art can understand that all or part of the steps of implementing the above method embodiments can be completed by program instructions related to hardware, the aforementioned program can be stored in a computer-readable storage medium, and when the program is executed, execute It includes the steps of the above method embodiments; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other media that can store program codes.

最后应说明的是:以上实施例仅用以说明本发明的技术方案,而非对其限制;尽管参照前述实施例对本发明进行了详细的说明,本领域的普通技术人员应当理解:其依然可以对前述各实施例所记载的技术方案进行修改,或者对其中部分技术特征进行等同替换;而这些修改或者替换,并不使相应技术方案的本质脱离本发明各实施例技术方案的精神和范围。Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be The technical solutions described in the foregoing embodiments are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1.一种卫星通信系统中的上行同步方法,其特征在于,包括:1. an uplink synchronization method in a satellite communication system, is characterized in that, comprises: 基站和终端与同一授时系统保持时间同步,通过相同的规则映射出下行帧基准时刻;The base station and the terminal maintain time synchronization with the same timing system, and map the downlink frame reference time through the same rules; 终端自行测量下行帧到达时刻与所述基准时刻的偏差,作为基站到终端的单向传输时延;The terminal measures the deviation between the arrival time of the downlink frame and the reference time by itself, as the one-way transmission delay from the base station to the terminal; 终端根据所述单向传输时延提前发送上行信号,以使所述上行信号在期望接收时间窗内到达基站侧。The terminal sends the uplink signal in advance according to the one-way transmission delay, so that the uplink signal reaches the base station side within the expected receiving time window. 2.根据权利要求1所述的方法,其特征在于,所述终端自行测量下行帧到达时刻与所述基准时刻的偏差,具体包括:2. The method according to claim 1, wherein the terminal measures the deviation between the arrival time of the downlink frame and the reference time by itself, specifically comprising: 终端检测基站在T1时刻发送的下行帧,记录检测到该下行帧的时刻为T2,计算二者偏差作为所述单向传输时延D=T2-T1。The terminal detects the downlink frame sent by the base station at time T1, records the time when the downlink frame is detected as T2, and calculates the difference between the two as the one-way transmission delay D=T2-T1. 3.根据权利要求2所述的方法,其特征在于,所述终端根据所述单向传输时延,提前发送上行信号,以使所述上行信号在期望接收时间窗内到达基站侧,包括:3. The method according to claim 2, wherein, according to the one-way transmission delay, the terminal sends an uplink signal in advance, so that the uplink signal reaches the base station side within an expected reception time window, comprising: 终端以期望接收时刻T3为基准,提前一个传输时延D发送上行信号,以使所述上行信号在起始位置早于T3、结束位置大于T3+T_duration的期望接收时间窗口到达基站侧;The terminal takes the expected reception time T3 as a reference, and sends the uplink signal one transmission delay D in advance, so that the uplink signal reaches the base station side in the expected reception time window whose starting position is earlier than T3 and whose ending position is greater than T3+T_duration; 其中,所述T_duration为所述上行信号的持续时长。Wherein, the T_duration is the duration of the uplink signal. 4.根据权利要求3所述的方法,其特征在于,所述期望接收时刻T3由基站侧通过广播信息以明示信息或暗示信息下发,或者由终端和基站各自根据本地时间和所述相同的规则各自计算得出。4. The method according to claim 3, wherein the expected reception time T3 is issued by the base station side with explicit information or implied information through broadcast information, or by the terminal and the base station according to local time and the same The rules are calculated individually. 5.根据权利要求1~4任意一项所述的方法,其特征在于,所述T1、T2和T3为相对时间、绝对时间或者某帧号内的某时隙。5 . The method according to claim 1 , wherein the T1 , T2 and T3 are relative time, absolute time or a certain time slot in a certain frame number. 6 . 6.根据权利要求1所述的方法,其特征在于,所述基站和终端与同一授时系统保持时间同步,通过相同的规则映射出下行帧基准时刻,包括:6. The method according to claim 1, wherein the base station and the terminal maintain time synchronization with the same timing system, and map the downlink frame reference time through the same rule, comprising: 基站和终端均与GNSS或1588V2同步,获取1PPS授时;Both the base station and the terminal are synchronized with GNSS or 1588V2 to obtain 1PPS timing; 基站和终端均基于1PPS信息生成帧边界定时,并据此分配帧号。Both the base station and the terminal generate frame boundary timing based on the 1PPS information, and assign frame numbers accordingly. 7.根据权利要求6所述的方法,其特征在于,所述终端自行测量下行帧到达时刻和所述基准时刻的偏差,作为基站到终端的单向传输时延;包括:7. The method according to claim 6, wherein the terminal measures the deviation between the arrival time of the downlink frame and the reference time by itself, as the one-way transmission delay from the base station to the terminal; comprising: 终端检测到下行帧,记录检测到该下行帧的时刻Trev;The terminal detects the downlink frame, and records the time Trev when the downlink frame is detected; 计算该时刻与本地基准定时对应的最新下行帧的边界时刻Tbase之差,Td=Trev-Tbase;Calculate the difference between this moment and the boundary moment Tbase of the latest downlink frame corresponding to the local reference timing, Td=Trev-Tbase; 计算该下行帧的帧号与本地基准定时对应的最新下行帧的帧号之差N,Calculate the difference N between the frame number of the downlink frame and the frame number of the latest downlink frame corresponding to the local reference timing, 计算所述单向传输时延D=Td+N*帧长。Calculate the one-way transmission delay D=Td+N*frame length. 8.根据权利要求6所述的方法,其特征在于,所述终端自行测量下行帧到达时刻和所述基准时刻的偏差,作为基站到终端的单向传输时延;包括:8. The method according to claim 6, wherein the terminal measures the deviation between the arrival time of the downlink frame and the reference time by itself, as the one-way transmission delay from the base station to the terminal; comprising: 终端检测到下行帧,记录检测到该下行帧的时刻Trev;The terminal detects the downlink frame, and records the time Trev when the downlink frame is detected; 计算该时刻与本地基准定时对应的最新下行帧的边界时刻Tbase之差,Td=Trev-Tbase;Calculate the difference between this moment and the boundary moment Tbase of the latest downlink frame corresponding to the local reference timing, Td=Trev-Tbase; 比较该下行帧的帧号和本地基准定时对应的最新下行帧的帧号的奇偶属性:Compare the frame number of the downlink frame with the parity attribute of the frame number of the latest downlink frame corresponding to the local reference timing: 如果二者奇偶属性相同,则所述单向传输时延D=Td;If the parity attributes of the two are the same, the one-way transmission delay D=Td; 如果二者奇偶属性不同,则所述单向传输时延D=Td+帧长。If the parity attributes of the two are different, the one-way transmission delay D=Td+frame length. 9.根据权利要求7或8所述的方法,其特征在于,所述终端根据所述单向传输时延提前发送上行信号,以使所述上行信号在期望接收时间窗内到达基站侧,包括:9. The method according to claim 7 or 8, wherein the terminal sends an uplink signal in advance according to the one-way transmission delay, so that the uplink signal reaches the base station side within the expected receiving time window, comprising: : 终端以所述Trev为基准,提前2个所述单向传输时延2*D发送上行信号。Using the Trev as a reference, the terminal sends the uplink signal two times in advance of the one-way transmission delay 2*D. 10.根据权利要求1~9任意一项所述的方法,其特征在于,所述基站为星上基站或地面基站或星上基站和地面基站。10 . The method according to claim 1 , wherein the base station is an on-board base station or a ground base station or an on-board base station and a ground base station. 11 .
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