CN108761434B - Pseudo-range measurement method and system based on CDMA downlink signals - Google Patents

Abstract

Translated fromChinese

本发明公开了一种基于CDMA下行信号的伪距测量方法及系统，所述伪距为CDMA基站到用户的距离，该方法包括：接收CDMA下行信号；对接收到的CDMA下行信号进行导频序列相关峰搜索，获取导频序列最大相关峰出现位置的本地时刻t；将本地时刻t对导频周期进行去整取余，得到CDMA下行信号从基站发出到用户的传输时间；根据传输时间计算伪距。本发明突破了现有CDMA基站测距技术双向信息交互的局限性，同时又绕开了对CDMA同步信号解调的复杂过程，可以方便快速的实现用户对基站伪距的测量。

The invention discloses a pseudorange measurement method and system based on a CDMA downlink signal. The pseudorange is the distance from a CDMA base station to a user. The method includes: receiving a CDMA downlink signal; and performing a pilot sequence on the received CDMA downlink signal. Correlation peak search, to obtain the local time t where the maximum correlation peak of the pilot sequence appears; the local time t is used to round off the pilot cycle to obtain the transmission time of the CDMA downlink signal from the base station to the user; according to the transmission time, the pseudo distance. The invention breaks through the limitation of bidirectional information exchange of the existing CDMA base station ranging technology, and at the same time bypasses the complex process of demodulating the CDMA synchronization signal, and can conveniently and quickly realize the user's measurement of the base station pseudorange.

Description

Translated fromChinese

一种基于CDMA下行信号的伪距测量方法及系统A method and system for pseudorange measurement based on CDMA downlink signal

技术领域technical field

本发明涉及无源测距领域，尤其涉及一种基于CDMA下行信号的伪距测量方法及系统。The invention relates to the field of passive ranging, in particular to a pseudorange measurement method and system based on a CDMA downlink signal.

背景技术Background technique

目前现有的利用CDMA信号进行测距的原理都是基于用户手机向CDMA基站发射测距请求信号，基站收到请求信号之后经过计算处理将距离信息通过应答信号发送给用户手机。现有的测距技术必须依靠用户手机与CDMA信号基站信息交互才能实现测距。At present, the existing principle of using CDMA signals for ranging is based on the user's mobile phone transmitting a ranging request signal to the CDMA base station. The existing ranging technology must rely on the information interaction between the user's mobile phone and the CDMA signal base station to achieve ranging.

现有的测距方式对基于CDMA信号的测距过程中，CDMA信号测距必须完成用户手机与CDMA基站的双向交互，且用户手机需要发起测距请求的信息，测距过程较繁琐，易受到干扰；测距过程耗时较长，且测距过程中用户手机不能移动位置，否则测距不准确。In the existing ranging method based on CDMA signal ranging process, the CDMA signal ranging must complete the two-way interaction between the user's mobile phone and the CDMA base station, and the user's mobile phone needs to initiate ranging request information. The ranging process is cumbersome and vulnerable. Interference; the ranging process takes a long time, and the user's mobile phone cannot move during the ranging process, otherwise the ranging will be inaccurate.

发明内容SUMMARY OF THE INVENTION

本发明所要解决的技术问题是：针对现有技术存在的问题，提出一种基于CDMA下行信号的伪距测量方法及系统，可以快速、精确测量CDMA基站到用户接收机之间的伪距，获得较好的实时性，应用起来方便快捷，并可应用于数字电视信号导航定位中。The technical problem to be solved by the present invention is: in view of the existing problems in the prior art, a pseudorange measurement method and system based on a CDMA downlink signal is proposed, which can quickly and accurately measure the pseudorange between the CDMA base station and the user receiver, and obtain Better real-time performance, convenient and quick application, and can be applied to digital TV signal navigation and positioning.

本发明提供的一种基于CDMA下行信号的伪距测量方法，所述伪距为CDMA基站到用户的距离，其特征在于，包括：The present invention provides a pseudorange measurement method based on CDMA downlink signals, wherein the pseudorange is the distance from the CDMA base station to the user, and is characterized in that, it includes:

接收CDMA下行信号；Receive CDMA downlink signal;

对接收到的CDMA下行信号进行导频序列相关峰搜索，获取导频序列最大相关峰出现位置的本地时刻t；Perform a pilot sequence correlation peak search on the received CDMA downlink signal, and obtain the local time t where the maximum correlation peak of the pilot sequence appears;

将本地时刻t对导频周期进行去整取余，得到CDMA下行信号从基站发出到用户的传输时间；The local time t is rounded off to the pilot frequency to obtain the transmission time of the CDMA downlink signal sent from the base station to the user;

根据传输时间计算伪距。Pseudoranges are calculated from the transit time.

本发明的另一方面提供的一种基于CDMA下行信号的伪距测量系统，所述伪距为CDMA基站到用户的距离，包括：Another aspect of the present invention provides a pseudorange measurement system based on a CDMA downlink signal, where the pseudorange is the distance from a CDMA base station to a user, including:

接收单元，用于接收CDMA下行信号；a receiving unit for receiving CDMA downlink signals;

搜索单元，用于对接收到的CDMA下行信号进行导频序列相关峰搜索，获取导频序列最大相关峰出现位置的本地时刻t；a search unit, configured to perform a pilot sequence correlation peak search on the received CDMA downlink signal, and obtain the local time t where the maximum correlation peak of the pilot sequence appears;

计算单元，用于将本地时刻t对导频周期进行去整取余，得到CDMA下行信号从基站发出到用户的传输时间，并根据传输时间计算伪距。The calculation unit is used for rounding off the pilot period at the local time t to obtain the transmission time of the CDMA downlink signal sent from the base station to the user, and calculating the pseudorange according to the transmission time.

本发明的另一方面提供的一种计算机可读存储介质，其上存储有计算机程序，所述计算机程序被处理器执行时实现如下步骤：Another aspect of the present invention provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the following steps are implemented:

对接收到的CDMA下行信号进行导频序列相关峰搜索，获取导频序列最大相关峰出现位置的本地时刻t；Perform a pilot sequence correlation peak search on the received CDMA downlink signal, and obtain the local time t where the maximum correlation peak of the pilot sequence appears;

将本地时刻t对导频周期进行去整取余，得到CDMA下行信号从基站发出到用户的传输时间；The local time t is rounded off to the pilot frequency to obtain the transmission time of the CDMA downlink signal sent from the base station to the user;

根据传输时间计算伪距。Pseudoranges are calculated from the transit time.

与现有技术相比，本发明突破了现有CDMA基站测距技术双向信息交互的局限性，同时又绕开了对CDMA同步信号解调的复杂过程，可以方便快速的实现用户对基站伪距的测量。Compared with the prior art, the present invention breaks through the limitation of the two-way information exchange of the existing CDMA base station ranging technology, and at the same time bypasses the complex process of demodulating the CDMA synchronization signal, and can conveniently and quickly realize the pseudo-range of the base station by the user. Measurement.

附图说明Description of drawings

本发明将通过例子并参照附图的方式说明，其中：The invention will be described by way of example and with reference to the accompanying drawings, in which:

图1为基于CDMA下行信号进行伪距测量时的信号传输模型示意图；1 is a schematic diagram of a signal transmission model when performing pseudorange measurement based on a CDMA downlink signal;

图2为导频序列相关峰时间间隔的示意图；Fig. 2 is the schematic diagram of pilot sequence correlation peak time interval;

图3为基于CDMA下行信号进行伪距测量的示意图。FIG. 3 is a schematic diagram of pseudorange measurement based on a CDMA downlink signal.

具体实施方式Detailed ways

本说明书中公开的所有特征，或公开的所有方法或过程中的步骤，除了互相排斥的特征和/或步骤以外，均可以以任何方式组合。All features disclosed in this specification, or all disclosed steps in a method or process, may be combined in any way except mutually exclusive features and/or steps.

本说明书中公开的任一特征，除非特别叙述，均可被其他等效或具有类似目的的替代特征加以替换。即，除非特别叙述，每个特征只是一系列等效或类似特征中的一个例子而已。Any feature disclosed in this specification, unless expressly stated otherwise, may be replaced by other equivalent or alternative features serving a similar purpose. That is, unless expressly stated otherwise, each feature is but one example of a series of equivalent or similar features.

如图1所示，图1示出了基于CDMA下行信号进行伪距测量时的信号传输模型。用户接收机接收来自CDMA基站发出的下行信号，通过本发明提出的伪距测量方法完成基站到用户的伪距测量。As shown in FIG. 1 , FIG. 1 shows a signal transmission model when pseudorange measurement is performed based on a CDMA downlink signal. The user receiver receives the downlink signal sent from the CDMA base station, and completes the pseudorange measurement from the base station to the user through the pseudorange measurement method proposed by the present invention.

根据分析发现CDMA信号下行链路发射功率为43dBm，其中15％被用于导频信道。在CCIR城市模式中15％建筑密度情况下蜂窝系统的传输损耗为(d_km表示基站到用户的距离，单位为km)：According to the analysis, it is found that the downlink transmission power of the CDMA signal is 43dBm, of which 15% is used for the pilot channel. The transmission loss of the cellular system in the case of 15% building density in the CCIR urban model is (d_km represents the distance from the base station to the user, in km):

L(dB)＝126.93+36.4log₁₀d_kmL(dB)=126.93+36.4log₁₀ d_km

在山区无城市建筑遮挡情况下蜂窝系统的传播损耗为(d_m表示基站到用户的距离，单位为m)：The propagation loss of the cellular system in the case of no urban building blockage in the mountainous area is (d_m represents the distance from the base station to the user, in m):

L(dB)＝20log₁₀(4·π·f·d_m/c)L(dB)=20log₁₀ (4·π·f·d_m /c)

我国CDMA(IS-95标准)下行信号的传输频段为867MHz-880MHz之间，根据蜂窝信号的覆盖特点，手机用户可以接收到唯一的基站强信号。根据蜂窝网的特点，可以确定每个蜂窝最远覆盖距离不会超过CDMA信号一个导频序列周期内传输的距离(CDMA下行信号一个导频周期时间为80/3(ms)，无线电信号在该时间间隔内可以传输约8000km)。my country's CDMA (IS-95 standard) downlink signal transmission frequency range is between 867MHz-880MHz. According to the coverage characteristics of cellular signals, mobile phone users can receive the only strong signal from the base station. According to the characteristics of the cellular network, it can be determined that the farthest coverage distance of each cell will not exceed the distance transmitted in one pilot sequence cycle of the CDMA signal (a pilot cycle time of the CDMA downlink signal is 80/3 (ms), and the radio signal in this It can transmit about 8000km in time interval).

图2示出了导频序列相关峰时间间隔。根据CDMA下行信号的特点，本发明提出了一种快速方便的测距方法。Figure 2 shows the pilot sequence correlation peak time interval. According to the characteristics of the CDMA downlink signal, the present invention proposes a fast and convenient ranging method.

如图3所示，用户接收机接收CDMA下行信号，对接收到的CDMA下行信号进行导频序列相关峰搜索和相关峰出现时刻精确捕获，记录搜索到的导频序列最大相关峰出现位置的本地时刻t。As shown in Figure 3, the user receiver receives the CDMA downlink signal, searches the received CDMA downlink signal for the correlation peak of the pilot sequence and accurately captures the occurrence time of the correlation peak, and records the local location of the maximum correlation peak of the searched pilot sequence. time t.

由于导频序列的起始时刻是整数倍的导频周期，因此用户接收机搜索到的导频序列最大相关峰出现的位置表示发射时刻t₀为80/3(ms)的n倍，其中n为整数，根据分析可以得出发射时刻t₀为n*80/3(ms)。Since the start time of the pilot sequence is an integer multiple of the pilot cycle, the position of the maximum correlation peak of the pilot sequence searched by the user receiver indicates that the transmission time t₀ is n times 80/3 (ms), where n is an integer. According to analysis, it can be concluded that the transmission time t₀ is n*80/3 (ms).

经过对CDMA下行信号传输特性的分析，由于传输距离不会超过一个导频周期内信号的距离，因此可以得出以下结论：t₀-t≤80/3(ms)。分析发现只需要对本地时刻t对导频周期进行去整取余，所得到的余数就是CDMA下行信号从基站发出到用户的传输时间：dt_传输＝mod(t,80/3)，t单位为ms，mod(A,B)表示A对B进行去整取余。将得到的传输时间乘以无线电信号在空气中的传输速度即可以得到基站到用户接收机的距离：L＝c·mod(t,80/3)/1000，其中c表示无线电信号在空气中的传播速度约为3×10⁸m/s，L的单位为m。After analyzing the transmission characteristics of the CDMA downlink signal, since the transmission distance will not exceed the distance of the signal in one pilot cycle, the following conclusion can be drawn: t₀ -t≤80/3(ms). The analysis finds that it is only necessary to round off the pilot cycle at the local time t, and the obtained remainder is the transmission time of the CDMA downlink signal from the base station to the user: dt_transmission = mod(t, 80/3), and the unit of t is ms, mod(A, B) means that A rounds off B. The distance from the base station to the user receiver can be obtained by multiplying the obtained transmission time by the transmission speed of the radio signal in the air: L=c·mod(t,80/3)/1000, where c represents the distance of the radio signal in the air. The propagation speed is about 3×10⁸ m/s, and the unit of L is m.

由于用户接收机对CDMA下行信号的接收采样速率决定了导频序列相关峰搜索提取的精度，最终影响传输时间测量以及距离测量精度。经过多次仿真比较发现接收信号的采样速率越高测距精度也越高，但是在实际应用中由于采样速率的提高对硬件性能的要求很高，因此实际应用是应当选择合适的采样速率。在一些实施例中，采样速率必须满足带通采样定理。Since the sampling rate of the CDMA downlink signal received by the user receiver determines the precision of the search and extraction of the correlation peak of the pilot sequence, it ultimately affects the transmission time measurement and the distance measurement precision. After several simulations and comparisons, it is found that the higher the sampling rate of the received signal, the higher the ranging accuracy. However, in practical applications, the improvement of the sampling rate requires high hardware performance, so the practical application should choose an appropriate sampling rate. In some embodiments, the sampling rate must satisfy the bandpass sampling theorem.

本发明并不局限于前述的具体实施方式。本发明扩展到任何在本说明书中披露的新特征或任何新的组合，以及披露的任一新的方法或过程的步骤或任何新的组合。The present invention is not limited to the foregoing specific embodiments. The present invention extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims (3)

1. A pseudo-range measurement method based on CDMA downlink signals, wherein the pseudo-range is the distance from a CDMA base station to a user, and the method is characterized by comprising the following steps:

receiving a CDMA downlink signal;

carrying out pilot frequency sequence correlation peak search on a received CDMA downlink signal to obtain a local time t of the position where the maximum correlation peak of a pilot frequency sequence occurs;

removing the whole surplus of the pilot frequency period at the local time t to obtain the transmission time of the CDMA downlink signal from a base station to a user;

calculating a pseudo range according to the transmission time;

the distance from the base station to the user receiver can be obtained by multiplying the obtained transmission time by the transmission speed of the radio signal in the air: l ═ c · mod (t, 80/3)/1000, where c represents the propagation velocity of a radio signal in air, which is approximately 3 × 10⁸m/s, mod (A, B) denotes A rounding off B, t is the local time, and L is in m.

2. The system according to claim 1, wherein the pseudorange is a distance from a CDMA base station to a user, comprising:

A receiving unit, configured to receive a CDMA downlink signal;

a searching unit, configured to perform pilot sequence correlation peak search on a received CDMA downlink signal, and obtain a local time t of an occurrence position of a maximum correlation peak of a pilot sequence;

and the calculating unit is used for removing the whole surplus of the local time t to the pilot frequency period to obtain the transmission time of the CDMA downlink signal from the base station to the user and calculating the pseudo range according to the transmission time.

3. The computer-readable storage medium of a CDMA downlink signal based pseudorange measurement method according to claim 1, wherein said computer program is stored thereon, and when executed by a processor, implements the steps of:

carrying out pilot frequency sequence correlation peak search on a received CDMA downlink signal to obtain a local time t of the position where the maximum correlation peak of a pilot frequency sequence occurs;

removing the whole surplus of the pilot frequency period at the local time t to obtain the transmission time of the CDMA downlink signal from a base station to a user;

the pseudoranges are computed from the time of transmission.

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