KR100211582B1 - Method and apparatus for detecting received time of paging data synchronized with gps timing in paging systems - Google Patents

Abstract

A receiving step of receiving and converting an RF signal into an audio signal; A conversion process of converting the received signal into a digital signal; A symbol synchronization process for finding a synchronization pattern among the received signal patterns; A symbol demodulation process of performing demodulation after selecting and receiving an initial 112 bits from the found synchronization patterns; A timing extraction step of determining a time taken to receive and demodulate a Sync1 pattern in the symbol demodulator; Finally, by using the reception time detector composed of a clock determination process for determining the reception time of the data frame,

By acquiring time synchronization for GPS timing, the GPS receiver, which has a lot of installation constraints for use in cellular and PCS base stations, can be replaced by a very small FLEX paging receiver.

Description

Receiving time detection method and apparatus for paging data synchronized with GPS time of high speed paging system

The present invention relates to a method for acquiring reference time synchronization for digital mobile communication systems such as CDMA Cellular (Code-Division Multiple Access Cellular) and PCS (Personal Communication System).

More specifically, the paging data transmitted from the high-speed paging system is synchronized with the GPS (Global Positioning System) reference time, so it receives the GPS reference time and extracts the GPS reference time, thus requiring digital movement such as CDMA cellular and PCS. A simple method and apparatus for providing synchronization time for a communication system.

A paging system refers to a system that provides various pager services to each pager wirelessly. When a paging terminal sends data for calling to a base station or a control station that serves a cell, which is an area allocated from a paging terminal, the corresponding base station transmits the corresponding data. The radio page signal is sent to the pager of the area.

At this time, each base station sets a reference time, all base stations should transmit the ho data at the same time. The reason for this is to prevent the pager terminal located in the region where the cell region of the base station overlaps with the same call from multiple base stations, thereby reducing the error rate of the received data.

In general, there are two ways to obtain system-to-system synchronization. The first method is to generate the reference time by itself, and the second method is to obtain the reference time from another precise reference time generating device.

The first method has the advantage that, in a single independent system, it generates its own reference time so that the necessary time and frequency signals can be freely used in the system.

However, as in a cellular network, when time synchronization is required between a plurality of control stations and base stations, several control stations and base stations cannot use such independent reference time.

Designed to solve this problem, the second method above uses one reference time receiver.

In order to achieve time synchronization between systems, all base stations must receive reference time from the same reference time receiver and synchronize all systems. The method of receiving a synchronization signal from an external reference time receiver may be performed through a wire or wirelessly. The accuracy of the reference time required by each system and the efficiency of the supply method are usually determined by the characteristics of the network.

In CDMA cellular and PCS systems, only a few seconds of system time error is allowed, so a time synchronization method using satellites is widely used for precise time synchronization.

The time synchronization of conventional CDMA and PCS is most commonly obtained using a GPS receiver. Each control station and base station receive a 1 PPS, 10 MHz signal, etc. as a synchronization signal using a GPS receiver, and all stations transmit the hodata according to this synchronization signal. To this end, a GPS receiver is provided for each control station and base station to obtain a reference time of the system.

The CDMA system set international reference time by defining 00:00:00 as 0 on January 6, 1980 and set it equal to GPS time 0. The GPS receiver calculates the exact hour, minute, and second from the sync signal received from the satellite so that the hodata can be sent.

However, signals from GPS satellites are very weak and can only be received at locations that can receive satellite signals directly outside the building on the ground section. Therefore, it is almost impossible to acquire a GPS signal inside most buildings. Therefore, the GPS receiving antenna of each control station and base station should be installed on the roof of a building in which the station is installed.

When the GPS receiving antenna is to be installed outdoors and the base station is indoors, it becomes difficult when the distance between the GPS antenna and the base station exceeds a certain range. In general, when the GPS antenna is more than 100m away from the base station receiving end, supplementary work such as installing an amplifier on the GPS receiving line should be performed.

Even when the system is to be installed in the underground space, the GPS antenna should always be installed on the ground, which leads to difficulties in connecting the transmission path between the GPS antenna and the base station GPS signal receiver.

The problem may not be so large in large systems where the installation of the GPS antenna and the required transmission path is not a big burden, but in small systems this can be a serious burden.

As the present and future trends in mobile communication are gradually shifting toward small capacity and low cost equipment, base stations and related devices must go in a simple and low cost form in terms of base station installation and operation management.

As described above, when the conventional GPS receiver system is used for a purpose such as indoor service or underground space service other than the use for a large-capacity system or an outdoor service, there is a problem that the efficiency is very low.

In order to acquire a synchronization signal of a system for indoor service and a system for service such as underground space, there is a need to provide a GPS signal acquisition method that is simpler than the conventional GPS receiver and has less influence of a reception position.

In addition, as the trend of the development of mobile communication base stations is becoming smaller, the size and cost of GPS receivers are relatively technically limited despite the continued miniaturization and low cost of channel cards and RF units. exist.

The present invention has been devised to solve the above problems, and instead of receiving a GPS signal directly from a satellite using a GPS receiver at each base station, a GPS synchronization signal of a fast paging terminal using a GPS synchronization signal is used. ,

The first object is to devise a method for detecting a paging data reception time synchronized with the GPS time of the high speed paging system, and a second object is to configure an apparatus for detecting paging data reception time synchronized with the GPS time of the high speed paging system. do.

1 is a flowchart of a method for detecting a reception time of paging data synchronized with GPS according to the present invention.

2 is a detailed operation diagram of a symbol synchronization process and a symbol demodulation process for demodulating fast paging data;

* Description of the symbols for the main parts of the drawings *

100: reception process 200: conversion process

300: symbol synchronization process 400: symbol demodulation process

500: timing extraction process 600: clock determination process

310: coarse demodulation step 320: maximum output selection step

410: sophisticated demodulation step 420: lock detection step

The present invention designed to achieve the first and second objects described above,

Receiving an RF signal; Converting the received analog signal into a digital signal; Performing symbol synchronization to find a synchronization pattern among the received signals; Performing symbol demodulation to receive and demodulate a Sync1 pattern among the sync patterns; Determining a GPS synchronization time based on a time demodulated by the symbol demodulator; Finally, the clock is determined to determine the reception time of the data frame.

Before the detailed description of the present invention, a brief description of the high-speed paging system will be given.

Recently, as the number of subscribers increases exponentially, there is a need for greater channel capacity due to congestion of limited channels. Paging protocols such as FLEX (Flexible) and APOCS have been developed.

In the FLEX protocol, each address for a terminal specifies a reference frame within 128 frames that appear on the channel every four minutes, so that the terminal receives a signal only at the time it appears. .

In other words, when frame 0 is synchronized at every hour, the terminal can derive the actual time from the current frame and cycle number, thus providing the user with the exact time that does not need to be adjusted within that time. The battery savings can be several times higher than that of the protocol.

The transmission speed can support all cases such as 1600, 3200, 6400bps faster than the existing 512, 1200bps, for example, can support up to 5 times the call volume than 1200bps POCSAG channel when operating at 6400bps.

The 1600bps FLEX system sends messages at frame 0, cycle 0 at GPS time on an hourly basis. Each cycle is sent 15 times an hour, each consisting of 128 frames.

Each frame is generated once every 1.875 seconds, and is composed of a synchronization pattern having information such as a speed and a clock of a data pattern that follows, and 10 data blocks containing contents of an actual electrolyte flow data.

The data block may have various speeds depending on the contents of the previously transmitted sync pattern. However, in the 1600 bps FLEX system, the sync pattern is transmitted at a speed of 1600 bps during the initial 115 ms of the frame.

The sync pattern consists of three patterns: Sync1, frame information, and Sync2. The Sync1 pattern, which consists of 112 bits at the beginning of the sync pattern, provides frame timing, 1600 bps symbol timing, and the speed of the data frame (block) that is transmitted following the sync pattern. 32-bit Bit Sync1 (abbreviated as BS1) and 32-bit Consists of four parts: A, 16 bits B, and 32 bits A '.

Here, the A pattern is a part for providing the speed of the data block following the synchronization pattern and can be selected from one of 16 standard patterns.

Table 1 shows the binary waveforms of the sync pattern that must appear in the 1600bps FLEX frame. In other words, if you see a pattern like this, it's a data frame for FLEX:

TABLE 1

Synchronization Pattern of FLEX System

Motive pattern Bit stream example speed Sync1 BS1 1010101010101010 1010101010101010 1600 bps A 0111100011110011 0101100100111001 B 0101010101010101 A ' 1000011100001100 1010011011000110 Frame information iiiiiiiiiiiiiiii iiiiippppppppppP Sync2 BS2 1010 C 1110110110000100 BS2 ' 101 C ' 0001001001111011

Among the sync patterns, the initial 32 bits of Sync1 are called A, and are 16 patterns of A1 to A15 having information such as the speed of the data pattern to be transmitted following the sync pattern, and Ar for re-sync. have.

Table 2 shows the information defined according to each pattern of A among the synchronization patterns of the 1600bps FLEX system. The undefined parts A5 to A15 are preliminary means for allowing new system features to be added as additional block information that can be defined as needed.

TABLE 2

Data frame rate according to A binary waveform

Frame rate A binary waveform A1 1600 / 2FM 0111100011110011 0101100100111001 A2 3200 / 2FM 1000010011100111 0101100100111001 A3 3200 / 4FM 0100111110010111 0101100100111001 A4 6400 / 4FM 0010000101011111 0101100100111001 A5 1101110101001011 0101100100111001 ... A15 1111000110011101 0101100100111001 Ar Resync 1100101100100000 0101100100111001

The 16-bit frame information pattern following the Sync1 pattern in the sync pattern provides a data transmission point, and the Sync2 pattern is designed to provide a sync clock for the data block transmission rate in the frame.

Hereinafter, with reference to the accompanying drawings will be described in detail the operation of the present invention.

1 is a flowchart of a method for detecting a reception time of paging data synchronized to a GPS according to the present invention.

As shown, a receiving process 100 for receiving an RF signal; An analog to digital conversion process 200 for converting the received signal into a digital signal; A symbol synchronization process 300 to find a synchronization pattern among the received signals; A symbol demodulation process 400 for receiving and demodulating a Sync1 pattern; A timing extraction process 500 for extracting timing based on the time demodulated by the symbol demodulator; Finally, it consists of a clock determination process 600 for accurately determining the time of GPS synchronized data reception.

The reception process 100 receives an RF signal (320 MHz band) and then down-converts (demodulates) the audio signal to an audio frequency band.

The analog / digital conversion process 200 converts the audio signal received from the receiver into a digital signal of 0 or 1.

The symbol synchronization process 300 inputs a pattern input by selecting the maximum output by correlating the first 112 bits of the pattern with 16 Sync1 standard patterns at the same time to find a synchronization pattern transmitted at the beginning of every frame of the fast paging system. Searching of any of these 16 standard patterns is performed.

In the symbol demodulation process 400, an initial 112 bits are received for 70 ms at a speed of 1600 bps to receive a Sync1 pattern among the sync patterns selected by the symbol synchronizer 300. When the reception is completed, the timing extraction process 500 is transmitted.

The timing extraction process 500 extracts the necessary timing by receiving the reception completion time point from the symbol demodulation process 400.

In addition, at the time of receiving the Sync1 pattern determined in the symbol demodulation process 400, the time at which the frame first arrived, i.e., the time for selection reception and demodulation of the Sync1 pattern and the processing time for detection of the reception time are determined. The paging system determines the reception time of the paging data transmitted in synchronization with GPS.

The clock determination process 600 calculates a GPS reference time from the timing extraction process 500 and provides the system to the system using the GPS reference time as a reference signal.

2 is a detailed operation diagram of a symbol synchronization process 300 and a symbol demodulation process 400 for demodulating fast paging data.

As shown, the symbol synchronization process 300 includes 16 coarse demodulation steps 310 for receiving a signal from the ADC 200 and performing first order coarse correlation, and a coarse demodulation step 310 for performing correlation. A maximum output selection step 320 for finding the largest output pattern of the outputs of < RTI ID = 0.0 >

The symbol demodulation process 400 receives an input from the analog / digital conversion process 200 and the maximum output selector, performs sophisticated demodulation, and transmits the completion time and the reception time to the timing extraction process 500. A fine demodulation step (Fine Correlation) 410, and a lock detector step (Lock Detector) 420 for fixing the synchronization pattern found in the symbol synchronization process (300).

The digitally converted signals from the analog / digital conversion process 200 are each subjected to 16 coarse demodulation steps 310. In each coarse demodulation step 310, 16 standard patterns of Sync1 are memorized and then one pattern of 16 can be found by performing correlation between the input pattern and each stored standard pattern. .

The maximum output selection step 320 checks whether the input pattern matches any of the 16 standard patterns by checking the correlated output value, and transmits the matched standard pattern to the symbol demodulation process 400.

The sophisticated demodulation step 410 receives the Sync1 pattern transmitted during the initial 70 ms of the synchronization pattern input from the analog / digital conversion process 200 and is selected in the maximum output selection step 320 to be locked detection step 420. Again perform precise demodulation with the locked standard pattern.

In the timing extraction process 500, when it is confirmed that the pattern received through the demodulation between the reception pattern and the Sync1 pattern is a Sync1 pattern in the sophisticated demodulation step 410, the time taken to receive and demodulate the Sync1 pattern is checked. Finally, it is possible to detect the time at which the paging data synchronized with the GPS is received in the clock determination process 600.

Since the reception time of the paging data thus determined is exactly GPS synchronized at the paging terminal, it can be used to determine the exact reference time to be used by the base station.

An apparatus configured to achieve the second object of the present invention,

A reference time receiver operating as described above,

A receiving unit for receiving an RF signal; An analog to digital converter (ADC) for converting a received signal into a digital signal; A symbol synchronizer for finding a synchronization pattern among the received signals; A symbol demodulator for receiving and demodulating a Sync1 pattern; A timing extractor configured to extract timing based on the time demodulated by the symbol demodulator; Finally, it characterized in that it comprises a clock determiner for accurately determining the time of GPS synchronized data reception.

Therefore, the present invention uses a reference time receiver configured as described above, and instead of transmitting data already synchronized with GPS time from the paging terminal to the pager in synchronization with the base station, the data is received from the base station. After detecting only the sync pattern transmitted during the initial 115 ms, the time taken to receive the sync pattern and the time taken to detect it by the final completion time can be determined to determine the time when the data frame was received.

In this case, since the time when the data frame is received is exactly GPS-synchronized by the paging terminal, the reference time used by the base station can be determined using this reception time.

The reason for detecting the sync pattern here is that by demodulating the sync pattern, it is possible to confirm whether the received data frame matches the frame for the paging system.

Since the reception time of the frame thus determined is already synchronized with the paging terminal, paging data accurately synchronized to the GPS can be transmitted by detecting the reference time and transmitting the ho data.

By using the reference time receiver according to the present invention configured as described above, the GPS synchronization time can be obtained by demodulating every frame synchronization data of the fast paging data, so that the base station can easily obtain the GPS reference time synchronization without the GPS receiver. have.

In addition, the high-speed paging receiver as described above can be made in a very simple configuration compared to the GPS receiver, it is possible to install a base station without the constraints of the installation of the GPS receiver, and thus the reception area is also relatively wider.

In addition, the present invention can replace the existing GPS receiver of the CDMA cellular and PCS base station, so it can be used in the small GPS synchronization device of the base station for the micro cell, pico cell.

Claims (9)

Detecting a synchronization pattern from the paging data received by the base station; A method for detecting a reception time of paging data synchronized with GPS time of a high speed paging system, comprising: determining a time at which a frame is received. The method of claim 1, wherein the determining of the time at which the frame is received comprises: And a time taken to receive a synchronization pattern and a time taken to detect the synchronization pattern from a final completion time. The method of claim 1 or 2, wherein the detecting of the synchronization pattern comprises A method of detecting a reception time of paging data synchronized with the GPS time of a fast paging system, detecting only a synchronization pattern transmitted for an initial 115 ms from the data received at a base station. The method of claim 3, wherein the detecting of the synchronization pattern is performed using a correlator. Means for receiving an RF signal; Means for converting the received signal into a digital signal; Means for finding a synchronization pattern among the received signal patterns; Means for receiving a Sync1 pattern found in the means for finding the synchronization pattern; Means for determining a time taken to receive a Sync1 pattern in the means for receiving the Sync1 pattern; And a means for finally determining a reception time of the data, wherein the reception time of the paging data is synchronized with the GPS time of the fast paging system. The method of claim 5, wherein the means for receiving the Sync1 pattern, And receiving and demodulating the initial 112 bits of the synchronization pattern, wherein the reception time detection apparatus for the paging data synchronized with the GPS time of the fast paging system. 7. The fast paging according to claim 5 or 6, wherein the means for finally determining the reception time of data is implemented by subtracting the reception time of the synchronization pattern and the detection time of the synchronization pattern from the reception completion time of the frame. Receiving time detection device for paging data synchronized with GPS time of system. 8. The apparatus according to claim 7, wherein the means for finding a synchronization pattern among the received signal patterns comprises: 16 coarse demodulation means each storing 16 standard synchronization patterns; And a means for selecting a maximum output pattern among the outputs of the coarse demodulation means. The method of claim 5 or 8, wherein the means for receiving the Sync1 pattern, Means for demodulating the pattern selected by the means for selecting the maximum output pattern from means for converting the received analog signal into a digital signal; And a means for fixing the pattern selected by the means for selecting the maximum output pattern, wherein the reception time of the paging data synchronized with the GPS time of the high-speed paging system.

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