CN1028946C

CN1028946C - Radio paging system having a plurality of transmitter stations

Info

Publication number: CN1028946C
Application number: CN 93101572
Authority: CN
Inventors: 市川善朗
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 1993-02-26
Filing date: 1993-02-26
Publication date: 1995-06-14
Anticipated expiration: 2013-02-26
Also published as: CN1091564A

Abstract

The present invention relates to a global wireless paging system. A maximum value of the sum of the transmission time of a paging request signal in a transmission line and the required time of each base station for processing the paging request signal is previously stored in a paging controller for receiving paging calls through a public switched telephone network, and a high accuracy time signal is generated according to a reference signal from a GPS (global positioning system) satellite. A high accuracy time signal is generated according to a reference time signal from the GPS satellite in each base station, and the paging request signal through the transmission line is processed according to the high accuracy time signal. A format of the paging request signal is converted into a digital paging signal so as to achieve intercarrier synchronous modulation.

Description

Radio paging system having a plurality of transmitter stations

The present invention relates to a kind of radio paging system, particularly relate to a kind of global radio paging system, wherein launch a plurality of same frequencys that have respectively at a distance of remote base stations, and by identical digital selective calling signal, i.e. the radio-frequency carrier synchronously modulated of paging signal from a plurality of.

In radio paging system, in order to make its overlay area bigger, a plurality of base stations that are separated from each other a preset distance are set usually, each base station has a power output to be about the radio transmitter of the 100W order of magnitude, and launch a plurality of same frequencys that have simultaneously, and by the radio-frequency carrier of identical digital paging signal modulation.In this radio paging system, in the zone that can receive from this radio-frequency carrier of two adjacent base stations, be in the interference region, need be limited in the phase difference between two reception carriers in the numerical value that is not more than a steady state value, this steady state value is usually in 1/4th scopes of a bit interval of digital paging signal.For example, adopting POCSAG(postcode standardization advisor group) the 512BPS digital paging signal of standard, promptly in the paging system of pocsag code, above-mentioned phase difference must be not more than 488 μ S.Therefore, need make the phase error of fixed phase in each base station be not more than 250 μ S.

On the other hand, between the switched telephone network of base station and paging receiving request, be equiped with a CCTV in such paging system.This CCTV comprises a paging controller, is used to carry out the format conversion convert predetermined signal type to from user's paging request msg, for example converts the page request signal form according to pocsag code to.

Interface between CCTV and the base station is made of cable or radio frequency time division multiplexer.In order to compensate by the delay that transmission caused of signal on the connecting circuit between CCTV and the base station, so that phase error is limited within the preset range (about 250 μ S), CCTV and base station are respectively equipped with variable deferred mount.On the other hand, United States Patent (USP) 4,709, the example that discloses a kind of paging system No. 401, CCTV wherein has the radio-frequency carrier signal of the phasing sign indicating number modulation of predetermined codes type to usefulness of base station emission, and receive this carrier signal by a base station and be demodulated into then and be the phasing sign indicating number, calculate and set a certain amount of delay according to the phasing sign indicating number for himself variable delay device again.

In general, since the above-mentioned connecting circuit between CCTV and the base station by a common route and an additional lanes by constituting, in the phase-locked system of above-mentioned United States Patent (USP), if because of the fault of circuit common switches to adjunct circuit from circuit common, just need rerun to the retardation of result of calculation and setting.

In addition, if the bit rate of digital paging signal further increases the new demand of the effective rate of utilization of radio-frequency carrier in order to satisfy, just not much of that according to the phasing precision of above-mentioned prior art.At this moment, be that desired phasing precision should be not more than 26 μ S in the radio paging system of pocsag code of 9600BPS in the corresponding bit rate.This just means that the phasing precision on a modulation input of transmitter must be within about 10 μ S, this is impossible in practice, because can produce the delay error between the different radio frequency transmission region and/or the phase error of transmitter inevitably on the modulation input of transmitter.In addition, in above-mentioned prior art, the variation of the retardation in the transmission line of connection CCTV and base station must be less than above-mentioned tolerable phase error.Yet, in the time division multiplexer circuit, be difficult to realize above-mentioned precision.Because the clock pulse of paging controller and time division multiplexer is normally separate, the signal delay that increases for the time division multiplexed signals that separates in the above-mentioned transmission line is constantly to change.Therefore, if the variation of limited delay amount, time division multiplexing will be limited, and just be necessary to increase the quantity of radio-frequency transmission line, thereby cause the maintenance cost of increase equipment and transmission line.

In addition, in order to expand area coverage, will increase the quantity of base station, this just needs to increase the connecting circuit quantity between CCTV and the base station, thereby the maintenance cost of equipment and connecting circuit is increased.

In order to address this problem effectively, can adopt a multipoint system, wherein, a plurality of base stations are connected on the circuit; Perhaps adopt tree-like connected system, a signal distributor wherein is set between CCTV and base station.Yet in multipoint system, therefore the structure of transmission line, when retardation changes, will make phasing become very difficult along with the place on line between CCTV and the base station changes.That is to say, can not produce any problem although appear at the variation of the retardation on CCTV's part transmission line on one side, because all phase places that are connected to the base station of CCTV all similarly change, but the variation meeting that occurs in base station retardation on one side causes phase error between base station.In tree system, although might shorten the total length of transmission line, the signal distributor of setting up also can correspondingly make the variation of retardation increase.Therefore, when the bit rate of digital paging signal increases, be difficult between the transmission output of a plurality of base stations and keep Phase synchronization.If use a plurality of signal distributors, be arranged on that the phasing in the level base station on one side will become very difficult behind the distributor.

Therefore, one object of the present invention just provides a kind of radio paging system, it has the connecting line that sends a digital paging signal to a plurality of base stations, thereby it is identical to send a plurality of frequencies to base station, and radio-frequency carrier with identical paging signal synchronous modulation, wherein the synchronization accuracy with digital paging signal modulated RF carrier wave can remain on very high accuracy, and is not subjected to postpone in the tie influence of variation.

Another object of the present invention provides a kind of radio paging system of the above-mentioned type, compares with the increase of base station quantity and the increase of radio-frequency carrier quantity, and this system can limit the increase of connecting line quantity.

The invention belongs to a kind of global paging system that is used to the interior a plurality of paging receivers of area coverage that are distributed in a plurality of base stations that paging service is provided, it comprises, a paging controller, respond one by the PSIN(public switched telephone network) the PSTN subscriber paging that receives, produce a page request signal that comprises called paging receiver holder's Subscriber Number, and a plurality of base stations, they are connected on the paging controller by the plurality of transmission lines with different transmission times, and respond above-mentioned page request signal respectively, generation has same frequency and by the radio-frequency carrier of a digital paging signal synchronous modulation, paging controller wherein comprises stores memory circuit a time of delay, be used for storing in advance a very first time value that equates with the transmission time difference maximum of transmission line, and store each base station of confession and receive this page request signal, and the second required time value of generation digital paging signal, one the one GPS(global positioning system) receiver, the signal that response receives from a plurality of NAVSTAR gps satellites, produce a time reference signal, very first time reference circuit responds this time reference signal, produce one and have the pinpoint accuracy time signal of predetermined time relation with the universal standard time, and extracode device, be used for after a moment, adding the coding of an express time for page request signal, as transmission start time assignment sign indicating number, coding wherein is by add what the very first time value and the second time value sum obtained on the existing time of being represented by the pinpoint accuracy time signal, and each base station comprises that all receives a buffer storage device, be used for receiving and temporary page request signal, the response of one the 2nd GPS receiver is from the signal of gps satellite, produce time-base signal, one second time reference circuit responds this timing reference signal, produce one and have the pinpoint accuracy time signal of predetermined time relation with the universal standard time, a coincidence circuit, be used for detecting at the transmission start time assignment sign indicating number that receives the page request signal that buffer storage device calculates and from the repeatability between the pinpoint accuracy time signal of the second time reference circuit, a format conversion, be used to carry out format conversion circuit, produce overlapping the moment of output signal synchronously converts page request signal to the digital paging signal from coincidence circuit with pinpoint accuracy time signal from the second time reference circuit, and a radio transmitter, be used to produce the radio-frequency carrier that has preset frequency and modulate by the digital paging signal.

According to radio paging system of the present invention, on the one hand transmission start time information is attached on the digital paging signal that constitutes the radio-frequency carrier modulation signal, on the other hand, in each base station, synchronously modulating a plurality of radio-frequency carriers that same frequency is arranged with paging signal by using from a moment as the pinpoint accuracy temporal information appointment of fiducial time of gps satellite.Therefore might when receiving modulated radio-frequency carrier, paging receiver prevent from the interference between the output signal of adjacent base station.

Can more clearly realize that above-mentioned and other purpose of the present invention, feature and advantage by detailed description below in conjunction with accompanying drawing, wherein:

Fig. 1 is the circuit block diagram of first embodiment of the invention;

Fig. 2 is the detailed circuit block diagram of the central control section in embodiment illustrated in fig. 1;

Fig. 3 is the detailed circuit block diagram of middle coding control section embodiment illustrated in fig. 1;

Fig. 4 is the workflow diagram of middle paging controller embodiment illustrated in fig. 1;

Fig. 5 is the sequential chart of the page request signal form in embodiment illustrated in fig. 1;

Fig. 6 is the sequential chart of the time location relation of the signal in the coding control section shown in Figure 3;

Fig. 7 is the sequential chart of the time location relation of middle modulation signal embodiment illustrated in fig. 1;

Fig. 8 is the circuit block diagram of second embodiment of the invention, and wherein each base station sends two mutually different non-modulation radio-frequency carriers;

Fig. 9 is a sequential chart, and it represents the time location relation of the modulation signal of second embodiment shown in Figure 8;

Figure 10 is the circuit block diagram of third embodiment of the invention;

Figure 11 is a sequential chart, and it represents the time location relation of the modulation signal among the 3rd embodiment shown in Figure 10; And

Figure 12 represents the system configuration of fourth embodiment of the invention.

Fig. 1 has represented paging system according to first embodiment of the invention with the form of block diagram, and a paging controller 10 that is located in the CCTV is connected to public switched telephone network (PSTN) 40, and from telephone terminal 41 paging receiving telephone signals.Paging controller 10 comprises that a PSTN interface unit 110 is used to control and being connected of PS TN40, and receive a paging call received signal that produces according to the paging call signal by PSTN40, central control unit 120 these paging call received signals of response, produce an additional page request signal that transmission start time assignment sign indicating number is arranged,

output interface unit

130 and 131 is responsible for page request signal is applied to respectively on the

transmission line

60 and 61 that is connected

base station

20 and 21, a subscriber data file 140 includes paging receiver 80(and only express one for convenience of explanation in Fig. 1) the registration/non-register information of Subscriber Number, and a GPS receiver 150 is used for from NAVSTAR GPS(navigation satellite time and range finding global positioning system) satellite 90 received signals, produce and very accurately synchronous clock pulse and temporal information of universal standard time, and they are offered central control unit 20.Base station 20 comprises that an input interface unit 210 is used for by transmission line 60 paging receiving request signals, a GPS receiver 230, it is similar to the working method of GPS receiver 150, be used for from gps satellite 90 received signals, and generation and very accurately synchronous clock pulse and temporal information of universal standard time, a coding control unit 220 is used for having the page request signal of transmission start time assignment sign indicating number to carry out format conversion to additional, convert thereof into the digital paging signal, and a transmitter 240, being used for the temporal information is the radio-frequency carrier of basis output with the modulation of digital paging signal.Base station 21 has the structure identical with base station 20, has therefore omitted its details in Fig. 1.

GPS receiver 150 may have identical structure with 230.It is to be noted, use the GPS receiver produce with the clock pulse of universal standard time synchronized and the means of temporal information be well-known, and at United States Patent (USP) 5, disclose a kind of in 134, No. 407 two methods of on remote point, calculating correct time according to this temporal information.The initial purpose of GPS receiver is orbit information and the time reference information detection position that is used for according to from a plurality of gps satellites, just determines the position of receiver.The atomic clock that uses caesium and rubidium is housed on each gps satellite, provides time difference information to this atomic clock from the earth with respect to the universal standard time.Therefore, atomic clock and universal standard time are identical substantially.Therefore, the temporal informations that produced by each

GPS receiver

150 and 230 within 5 μ S, demonstrate the very temporal information of pinpoint accuracy with respect to the error of universal standard time.

Fig. 2 has represented central control unit 120 in more detail.Central control unit 120 in Fig. 2 comprises a queued 121, be used for temporary from the paging call received signal of PSTN interface unit 110 and with its queuing, a queuing timer 123 is used to produce a timing signal TQ with predetermined space, this time interval telephone received signal distribution on time shaft, one time of delay memory 124, be used to store the maximum of the time of delay among processing time of time of delay of

transmission line

60 and 61 and

base station

20 and 21, one fiducial time pulse-generator circuit 125 be used for according to the output generation of GPS receiver 150 and the clock pulse and the temporal information of universal standard time synchronized, and control circuit 122, be used to control foregoing circuit, when receiving timing signal TQ, just the format conversion that has the phone acknowledge(ment) signal in the queued 121 is become one group of page request signal, also be used for according to pulse-generator circuit 115 output is represented by fiducial time existing time and by calculating transmission start time the time of delay that time of delay, memory 124 output was represented, for page request signal additional one with corresponding coding of the time that calculates, for example by

output interface unit

130 and 131 page request signal is offered

base station

20 and 21 respectively then.

Fig. 3 has represented coding control unit 220 in more detail.In Fig. 3, coding control unit 220 comprises a reception buffer 221, be used for receiving the additional page request signal that transmission start time assignment sign indicating number arranged and it is temporary from input interface unit 210, one fiducial time pulse-generator circuit 225 be used for according to the output generation of GPS receiver 230 and the clock pulse and the temporal information of universal standard time synchronized, coincidence circuit 222 is used for detecting by existing time that fiducial time, pulse was represented assignment overlapping between the time with the page request signal of reception buffer 221, and export one and send signal SS, a transmission data converter 224 is used for the format conversion of paging signal, convert thereof into the digital paging signal, and the digital paging signal is offered transmitter 240 as modulation signal, and a transmission control circuit 223 is carried out control according to sending signal SS, the page request signal that exists in the reception buffer 221 optionally is provided, and the control format conversion.

Hereinafter with reference to the digital paging signal is the working method that the situation of the pocsag code of 512BPS is described the foregoing description.

Referring to Fig. 1 and Fig. 2, whether paging controller 10 is constantly checked in its PSTN interface unit 110 has from arbitrary telephone terminal 41(S1) the paging request.If receive a phone, paging controller just begins to carry out the operation that receives called Subscriber Number (S2).In Japan, when the phone that is connected to PSTN was a trunk connection phone, called Subscriber Number was normally by a MF(multifrequency) the signal formation.Receive after the called Subscriber Number queued 121 subscriber data file 140(S3) check, only accept paging request to called party's number of in subscriber data file, having registered.If called user is identified as one of member that paging service is provided with information service (S4), just receive the PB(button) state information (S5) of signal.In this manner, receive a plurality of paging call request signals successively, and it is accumulated in the queued 121, until receiving timing signal TQ from queuing timer 123.Then, queued 121 produces a series of paging signals, and its form is very near pocsag code (S6).(this processing is called as queuing).

Control circuit 122 is when receiving the timing signal TQ with predetermined time interval, just the paging received signal that is accumulated in the queued 121 is carried out format conversion, convert thereof into the form of page request signal, on the current time that pulse generating circuit 125 shows by fiducial time, increase by one by time of delay memory 124 the output data presented transmission time and the reception and the processing time of base station one side, after spending the time of representing by the result who increases, adding a time, by output interface unit 130/131 and transmission line 60/61 signal is sent to base station 20/21 then as transmission start time for page request signal.

The host-host protocol of page request signal adopts the HDLC(high-level data link control procedure) as the second layer of OSI, and with form shown in Figure 5 layer 7 as OSI.In Fig. 5, sign (ID) number of a target base station of " TXNO " expression, " CHNO " is the channel number of an indication radio-frequency channel, the transmission data send by this channel, the specified format of the transmission data that " CODE " expression is sent out (for example POCSAG512BPS being " 01 "), " TIME " is the transmission start time assignment (for example being " 1000 " in the time of 12: 10: 0 under the situation of transmission) of transmission data, " TRNO " is a transaction number, indicate the id number of this grouping, and " TRL " be a transaction groups length, represents the data length of this grouping.In addition, concerning " POCS AG data ", only there are 21 information bits to be used as the code word transmission of 1 three byte, and at parity check bit of base station affix on one side, a header and a synchronize code words (SC).Adopt this scheme, can shorten transmission time by transmission line.Can clearly find from above description, be to seek to insert in the request signal transmission start time information at up each according to the feature of system of the present invention.

The id number numbering system of each base station is selectively, thereby not only allows to specify other base station, and can allow to specify simultaneously in the group or all base stations in all groups.Central control unit 120 is selected the id number of correspondence one transmission lines and the state of a base station, and setting " TXNO "." CHNO " uses when a base station has a plurality of radio-frequency channel.

In conjunction with Fig. 1 and 3 analysis charts 6, receive a page request signal that is transferred to itself or all base stations as that base station 20 of " TXNO ", coding control unit 220 is stored in this page request signal with in the reception buffer 221 of address segmentation.GPS receiver 230 to fiducial time pulse generating circuit 225 repetition period is provided is pulse signal C3 and the time signal C4 that delay is arranged with respect to signal C3 slightly with serial data mode of 1 second.Fiducial time, pulse-generator circuit 225 was equiped with high stability quartz (controlled) oscillator 226, so that obtain a more precise time according to the signal C3/C4 from GPS receiver 230.Because time signal C4 is later than pulse signal C3 supply pulse-generator circuit fiducial time 225 slightly, employing adds the time of reception of 1 second represented time as pulse signal C3 by the signal C4 that had before received, just might make time signal C4 and universal standard time synchronized.Fiducial time, pulse-generator circuit 225 each bit for transmission data converter 224 provided a clock pulse C1, and provide a clock pulse C2 for each code word, so that make digital paging signal format, i.e. transport format data DS bit-by-bit and code word ground is synchronously one by one.Fiducial time, pulse-generator circuit 225 temporal information also offered coincidence circuit 222, coincidence circuit 222 receives that whenever a pulse signal C3 is just from reading a transmission initial assignment time from " TIME " zone the page request signal of reception buffer 221, with its with compare from pulse-generator circuit 225 current time marker pulse fiducial time, and when two times overlap, export to transmission control unit (TCU) 223 together with the memory address of data sending a signal SS.Transmission control unit (TCU) 223 offers transmission data converter 224 again to the data corresponding with above-mentioned address in " POCSAG data " zone.Transmission data converter 224 is synchronously operated with clock pulse C1 and C2, be the additional parity check bit tp of the digital signal of input, further add a header and SC for digital signal, data-signal is converted to transport format data DS, provide it to transmitter 240 then as modulation signal.Transmitter 240 is used for radio-frequency carrier of digital paging signal modulation of autobiography transmission of data transducer 224, and it is sent as electromagnetic wave, thereby makes specific beep-pager 80 of digital paging signal call.Operate with universal standard time synchronized ground because base station 21 and base station 20 are same, just might be from each base station, be limited within the 1/4 bit length scope as the digital paging phase difference between signals of modulation signal.

As mentioned above, in according to system of the present invention, produce the benchmark of phase bit comparison by the GPS receiver of each base station, between each base station, can keep modulation signal synchronously, and be not subjected to the influence of the different time of delays on the transmission line between paging controller (CCTV) and each base station.

Referring to sequential chart shown in Figure 7, at moment TO place, from output interface unit 130 and page request signal of 131 outputs of CCTV's paging controller 10, this signal is specified a transmission start time TS.Behind a propagation delay time t1, the page request signal D1 that outputs to transmission line 60 is received and is temporarily stored in the base station 20 at moment T1 place.Behind a propagation delay time t2, the page request signal D2 that outputs to transmission line 61 is received and is temporarily stored in the base station 21 at moment T2 place.At moment Ts,

base station

20 and 21 forms the digital paging signal by the signal format conversion respectively, and begins to transmit the radio-frequency carrier with this digital paging signal modulation respectively.Paging controller 10 comes given transmission zero-time TS by going up the digital received and the processing time (tp among Fig. 7) that increase maximum traffic delay time (t2 among Fig. 7) and base station in the current time (TO among Fig. 7).If the present invention is used for calling out the system (referring to day disclosure 59-85147) in a transmission time that constantly specifies by the caller, just should export page request signal from paging controller than the time that fixed time TS shifts to an earlier date t2 and tp sum.

Fig. 8 is the circuit block diagram of second embodiment of the invention, and two radio-frequency carriers wherein being launched have different frequencies.Second embodiment shown in Figure 8 has such structure,, the base station in embodiment illustrated in fig. 1 20 and 21 is changed into the

base station

30 and 31 that has above-mentioned different radio frequency carrier wave separately that is.In Fig. 8, base station 30 has coding control unit 220 and 320 and

transmitter

240 and 340, radio channel CH1 and the CH2 to being applied to two radio-frequency carriers respectively.These the structure devices 26S Proteasome Structure and Function respectively with first embodiment shown in Figure 1 in coding controller 220 and transmitter 240 identical.Equally, adopt with Fig. 1 in same numeral other device 26S Proteasome Structure and Function also respectively with Fig. 1 in device identical.

The mode of operation of present embodiment is below described.When central control unit 120 received paging call from a telephone terminal 41 among the PSTN40, it was just according to the flow performing queuing handling procedure of Fig. 4.On the other hand, make among a plurality of paging receivers 80 and the 81(figure and only show two) radio channel CH1 of each autoregistration or CH2, and this transmission channel number information and Subscriber Number accordingly in the stores user data files 140.When central control unit 120 was carried out the queuing handling procedures, it confirmed called party's registration number according to subscriber data file 140, and it is distributed to the radio channel of each appointment, carried out the queuing handling procedure then.Central control unit 120 response timing signal TQ sequentially for each radio channel produces the page request signal (see figure 5), and send to base station 30/31 to them by transmission line 60/61.In each base station 30/31, identify the radio channel number in " CHNO " zone in the page request signal of receiving by input interface unit 210, if radio channel CH1 just sends it to coding control unit 220, if channel CH2 just passes to coding controller 320.Coding control unit 220 and the transmitter 240 of corresponding radio channel CH1 are worked independently of each other with coding control unit 320 and the transmitter 340 of corresponding radio channel CH2, and can be at the time of appointment difference call page receiver 80/81.In paging controller 10 and base station 30/31, be used for according to device identical with embodiment shown in Figure 1 from current time of signal accurate Calculation of GPS receiver 150/230.

Fig. 9 represents the input and the relation of the time location between output and the digital paging signal of page request signal various piece in the present embodiment.In Fig. 9, send a page request signal D11 and a page request signal D12 who has specified transmission time TS2 for wireless channel CH2 who has specified transmission time TS1 for wireless channel CH1 by output interface unit 130 to same transmission lines 60 successively from moment TO1 and TO2 respectively, through the delay of t1, base station 30 receives this two signals at moment T11 and T12 respectively.The coding control unit 220 of base station 30 is at the form of time T S1 switching signal D11, for channel CH1 forms a digital paging signal.Even the signal on the wireless channel CH1 continues to transmit, coding control unit 320 is at the form of time T S2 switching signal D12, for channel CH2 forms a digital paging signal.Signal D11/D12 also offers transmission line 61 from the output interface unit 131 of paging controller 10 at moment TO1/TO2 place, and through receiving by base station 31 after the delay different with t1.Certainly, on wireless channel CH1 and CH2, the emission zero-time of these paging signals is synchronous with the paging signal of base station 30 respectively.

As mentioned above, even the paging signal that a plurality of wireless channels send is overlapping in time, also might on a transmission lines, transmit these paging signals in the mode of timesharing, because on the page request signal that transmits by transmission line between paging controller 10 and each base station 30/31, added transmission start time assignment sign indicating number, so just needn't increase the quantity of transmission line herein.Certainly, the bit rate of the page request signal on the transmission lines should be the quantity of the N(wireless channel of its transformat) doubly.Yet doing so correspondingly to increase the time-sharing multiplex rate.For example to the situation of 512BPS pocsag code, if the bit rate of the page request signal on the transmission line is 9600BPS, just might multiplexing at least 10 channels.

Figure 10 represents the third embodiment of the present invention, wherein except the transmission line between paging controller 11 and the base station 20/21 has been made revise, other parts all with relevant embodiment in identical.In Figure 10, a transmission lines 70 is connected between the corresponding input interface unit 210 of output interface unit 130 of paging controller 11 and a plurality of base station 20/21 in the mode of multiple spot.When a page request signal when paging controller 11 is sent on the transmission line 70, " TXNO " can be assigned to all base stations.Yet, in this case, may be difficult to confirm whether normally received signal of a plurality of base stations on one side at paging controller 11.This is because conflict mutually from the normal affirmation signal (ACK) that receives of expression page request signal in each base station 20/21.For addressing this problem, page request signal is sent to base station 20/21 respectively, as shown in figure 11.Paging controller 11 transmits a page request signal D3 at time T O3, give an id number (TX1) that is assigned to base station 20 in its " TX NO " zone, transmit a page request signal D4 at time T O4 then, for it gives an id number (TX2) that is assigned to base station 21.Pass through respectively after propagation delay time t3 and the t4, base station 20/21 receives signal D3 and D4 in time T 3 and T4.Therefore, each base station 20/21 can be beamed back ack signal in the different time respectively.Certainly, need be arranged on transmission start time TS3 after the time T 5 that all base stations all receive page request signal fully.In this system, the bit rate of the page request signal that transmits by transmission line 70 must be paging signal bit rate in the base station M doubly, M herein is the base station quantity (M=2 in Figure 10) that is connected.Yet doing so correspondingly to increase the time-sharing multiplex rate.For example under the condition of 512BPS pocsag code,, just might on a transmission lines, connect at least 10 base stations if the bit rate of page request signal is 9600BPS on the transmission line.

Figure 12 represents the fourth embodiment of the present invention, it has tree-like joint construction, wherein in a transmission lines, be provided with a signal distributor 50 that is used for relaying/assigned paging signal, so that adapt to the increase of distance between paging controller 11 and each base station 20/21.In Figure 12, signal distributor 50 comprises that one is connected to from the input allocation units 510 on the transmission line 71 of paging controller 11, be used for receiving and the assigned paging request signal, and

output unit

520 and 521, they are used for each page request signal that input allocation units 510 are distributed is exported to

base station

20 and 21 via

transmission line

72 and 73 respectively.In the present embodiment, also may reduce the quantity of transmission line with respect to the quantity of base station as embodiment shown in Figure 10.

As indicated above, when receiving the modulated RF carrier wave, paging receiver can prevent interference between the adjacent base station output signal according to radio paging system of the present invention, this is because added a transmission start time information on the digital paging signal that constitutes the radio-frequency carrier modulation signal, this is on the one hand, on the other hand, in each base station, use very pinpoint accuracy temporal information from gps satellite as time reference, with one of its appointment constantly the place synchronously modulate the radio-frequency carrier of a plurality of same frequencys with paging signal.In addition, owing to can realize that with the paging signal transmission line between each base station multiple spot is connected at paging controller, tree-like connection or Y-connection and their combination in any connected mode, just might obtain Phase synchronization, thereby realize the synchronous transmission of a plurality of base stations, and correspondingly save transmission line quantity, and reduce its expense thus.

In Fig. 3, should be noted that, if can not obtain clock pulse and temporal information from GPS receiver 230, each base station fiducial time pulse-generator circuit 225 just by 226 controls of high stable quartz (controlled) oscillator.If bit rate is 9600BPS, oscillator 226 can adopt stability to be 0.01PPM or littler quartz (controlled) oscillator.If the bit rate of paging signal is lower than 9600BPS, the stability requirement of quartz (controlled) oscillator can reduce.Except using this automatic quartz (controlled) oscillator, a reserve arrangement also can be provided, utilize the synchronous clock pulse of transmission line to produce a time pulse with the clock phase synchronization of GPS receiver, also can utilize television broadcasting ripple or standard wave, for example a JJY.In the case, keep synchronously by reserve arrangement synchronously with the GPS receiver.Same method also is applicable to the pulse-generator circuit 125 fiducial time of paging controller among Fig. 2.At this moment, the stability of circuit 125 on one side can be lower with respect to base station.Therefore, can under the situation that does not have GPS receiver 150, adopt pulse-generator circuit fiducial time with this reserve arrangement.

Claims

1, a kind of global paging system, be used to a plurality of paging receivers in the overlay area that is distributed in a plurality of base stations that paging service is provided, this system comprises a paging controller, respond a paging call that receives through public switched telephone network (PSTN) from one of them user, produce a page request signal, this signal comprises called above-mentioned paging receiver holder's Subscriber Number, and above-mentioned a plurality of base station is connected on the above-mentioned paging controller by many transmission lines with different transmission times, and produce respectively and have same frequency, and by a radio-frequency carrier that digital paging signal is synchronously modulated of the above-mentioned page request signal of correspondence, this paging system is characterised in that:

Above-mentioned paging controller comprises:

One time of delay memory, be used for storing in advance a peaked very first time value that equals the different transmission times on the above-mentioned transmission line, and supply above-mentioned each base station from receiving above-mentioned page request signal to producing the second required time value of above-mentioned digital paging signal;

The one GPS receiver, the signal that response receives from a plurality of NAVSTAR GPS (global positioning system) satellite, generation time reference signal;

Very first time reference circuit responds above-mentioned time reference signal, produces the pinpoint accuracy time signal that has definite time relationship with the universal standard time; And

The coding attachment device, be used for being the additional code as the express time of transmission start time assignment sign indicating number of above-mentioned page request signal after a moment, the above-mentioned moment is by add that the very first time value and the second time value sum obtain on the current time; And

Each above-mentioned base station comprises:

One receives buffer storage device, is used for receiving and temporarily storing above-mentioned page request signal;

One the 2nd GPS receiver, response produces above-mentioned time reference signal from the signal of above-mentioned gps satellite;

One second time reference circuit responds above-mentioned time reference signal, produces the pinpoint accuracy time signal that has definite time system with the universal standard time;

A coincidence circuit is used for detecting at the transmission start time assignment sign indicating number of the above-mentioned page request signal that above-mentioned reception buffer storage device calculates and from the repeatability between the above-mentioned pinpoint accuracy time signal of the above-mentioned second time reference circuit;

A format conversion circuit, be used to carry out format conversion, produce a moment that overlaps output signal the format conversion of above-mentioned page request signal one-tenth and from the synchronous above-mentioned digital paging signal of the above-mentioned pinpoint accuracy time signal of the above-mentioned second time reference circuit from above-mentioned coincidence circuit; And

A radio transmitter is used to produce a radio-frequency carrier that has preset frequency and modulate with above-mentioned digital paging signal.

2, according to the paging system of claim 1, it is characterized in that the above-mentioned second time reference circuit comprises a high stability quartz (controlled) oscillator, its response is from the above-mentioned time reference signal of above-mentioned the 2nd GPS receiver, producing one is the clock pulse of each bit stipulated time position of above-mentioned digital paging signal, even and still keep when above-mentioned time reference signal is ended and produce above-mentioned clock pulse.

3, paging system according to claim 1 or 2, it is characterized in that above-mentioned radio-frequency carrier comprises a plurality of different carrier waves that have, the above-mentioned paging receiver of wherein each can receive different above-mentioned carrier waves, wherein above-mentioned paging controller comprises the above-mentioned coding attachment device of corresponding above-mentioned each carrier wave, the bit rate of above-mentioned page request signal equals the bit rate of above-mentioned digital paging signal and the product of above-mentioned number of carriers, each base station wherein includes the equipment of equal number, each equipment includes above-mentioned reception buffer storage device, the quantity of the corresponding above-mentioned carrier wave of the above-mentioned format conversion circuit wherein and the quantity of above-mentioned transmitter, and, launch above-mentioned carrier wave from above-mentioned base station in transmission start time by the above-mentioned time assignment sign indicating number appointment in the above-mentioned page request signal of above-mentioned each carrier wave of correspondence.