CN1027212C - Base station emulator - Google Patents

Abstract

The present invention relates to a radio digital telephone system which at least comprises a simulation base station and one or multiple user stations, wherein the simulation base station comprises a station similar to user stations, but the station similar to user stations has the function of triggering a synchronizing process. As a result, the station similar to user stations can assign a time slot to the user stations within the frame format of amplitude value signals, which is realized through monitoring positive jump edges in the signals.

Description

Base station emulator

Usually telephone system is just increasing the use wireless technology to be used for the long-distance telephone contact now, in some situation, brought into use digital technology, yet, in general the use, also there is not system can provide effective wireless digital technology to be used for getting in touch with each user's local call.Such technology has been disclosed in each nearest patent, and they are had by the application's assignee, and as the United States Patent (USP) on February 17th, 1987, the patent No. is the United States Patent (USP) on June 23rd, 4644561,1987, and the patent No. is 4675863.The disclosed technology of these patents provides base station and utilizes the digital radio time division circuit to carry out communication between central office and a plurality of user, but this circuit has the repetitive sequence time slot to combine with the specific user in the sendaisle bit stream.

The base station that uses above-mentioned time-division system is than complicated and costliness, but is worthwhile economically when being used for big system service in a large number of users.Yet, for the mini system of service small number of users, economically may be not too worthwhile.In addition, such system uses a pair of frequency, and one is used for sending, and another is used for receiving, and considers if single-frequency can use effectively higher superiority is arranged from the viewpoint of restriction frequency spectrum available channel.

Therefore, the object of the present invention is to provide to be referred to as the emulation base station, it can substitute actual base station effectively under a stable condition.

Another purpose is to provide a system, and it can be used for a plurality of users, but only uses a frequency job.

Other purpose will be found out from following description and claim.

In itself, in fact system of the present invention uses an improved subscriber board to serve as emulation or simulation base station (base station), takes this to reduce greatly the total cost and the complexity of system.But this emulation base station is different from subscriber board only is its triggering synchronous process, and subscriber unit only scans the RF(radio frequency of being sent by the emulation base station) signal, up to frequency and the time slot of finding to be assigned to it.At the interval that the RF signal sends, the emulation base station is used to receive the RF signal from subscriber board, in this way, subscriber unit both can be conversed with the emulation base station that serves as another subscriber station, also can with by another subscriber station conversation that it is synchronous of emulation base station.

Fig. 1 illustrates the block diagram that embodies total system of the present invention.

Fig. 2 is radio control channel (RCC) the waveform schematic diagram that is used for the standard base station.

Fig. 3 is for being used for RCC waveform schematic diagram of the present invention.

Fig. 4 is used for the synchronous received signals of process of the present invention just to jump schematic diagram along amplitude.

Fig. 5 is for being used to the synchronous circuit block diagram of the process that obtains in invention.

Fig. 6 is by being used for the agc circuit block diagram that received of the present invention.

Fig. 7 is used for the block diagram that the frequency acquisition circuit is shown of the present invention.

Fig. 8 is for embodying the schematic diagram of radio telephone system structure of the present invention.

Fig. 9 is for similar Fig. 8 but the schematic diagram of two-way custom system is shown.

Figure 10 is the schematic diagram of frame structure of the two-way custom system of Fig. 9.

Figure 11 is the schematic diagram of the frame structure of a plurality of two-way custom systems.

Figure 12 is for embodying the schematic diagram that is used to monitor the system of one or more functions of the present invention.

Figure 13 is the schematic diagram of embodiment relay station of the present invention system.

Figure 14 is for embodying the schematic diagram of a plurality of relay station of use of the present invention system.

Figure 15 is for driving the schematic diagram of the system of a plurality of relay stations and subscriber unit with single relay station.

The form of Fig. 1 and block diagram shows the whole interior work of this system, and it is designated as 10.This system is when conversation, and people's dialogue machine 12 is talked, and voice signal is sent to local call interface unit 14.This signal is by coding decoder (CODEC) 16 digitlizations, and resulting digital data stream is sent to speech processor 18, and it is with the data of speech data boil down to than low rate.Compressed data is then delivered to modulator-demodulator (MODEM) by lead 22 and bilateral switching 24, and modulator-demodulator is used for data flow is converted into the frequency spectrum analog signal.This analog signal is sent to radio device 26 by lead 28, and radio device upwards is converted into radio frequency (RF) signal with signal, sends this RF signal by antenna 30 then.

At the interval that the RF signal sends, this unit is used to receive the RF signal of a subscriber unit, and it is intermediate frequency (IF) signal that radio device 26 transforms each RF signal downwards, and this IF signal is delivered to MODEM20 by lead 32.MODEM20 demodulation IF signal is to form digital signal, and this signal is sent to speech processor by switch 24 and lead 36 then.This speech processor is a digitized voice signal with signal extension, and this voice signal is sent to CODEC16 then, and it gives phone 12 input analog voice signals by telephony interface 14.

Data transmission modes and aforesaid way are similar, but phone substituted by data terminal or computer 38, and phone, CODEC and speech processor are by the reversing arrangement institute bypass of switch 24, and this switch is coupled by lead 40 and 42.

MODEM20 and radio device 26 all are fed to control unit 44.Control unit 44 is arranged on predetermined time slot with MODEM at first, modulates and alignment pattern, and radio device is arranged on predetermined the RF frequency and power level.Yet when they can not be when subscriber station provides satisfied reception fully, these parameters can be adjusted by subscriber station.

In the system that uses real base station, the described system of the patent of for example above-mentioned numbering 4675863 sends waveform and is divided into multiple (promptly 45 milliseconds) frame.Every frame in turn is divided into four 11.25 milliseconds of time slots, and base station sends on four time slots to produce 100% work period modulation waveform, and quiescent region in addition is radio control channel (RCC).The RCC time slot is shorter slightly than 11.25 milliseconds, and this begins at every frame, causes a little gap in modulation, and this little gap is called as amplitude modulation dead space (AM hole).In fact the oscillogram of the RCC channel of base station form is shown among Fig. 2.Yet in system of the present invention, do not send 100% work period waveform, and only send a time slot (25% work period waveform), as shown in Figure 3 at every frame.The frame format of this modification must cause near-synchronous, the variation of automatic gain control (AGC) and frequency acquisition.Illustrate in these variation narrations below.

Near-synchronous

Because system of the present invention only uses 25% work period waveform, thereby its monitors the amplitude of received signal and searches for the just jumping edge of range signal.These are just being jumped along shown in Figure 4.Subscriber unit is adjusted the frame timing of self, to locate according to the appearance of just jumping the edge.

The circuit that is used for obtaining above near-synchronous is shown in Fig. 5 with the form of block diagram.Here, the received signal that illustrates is sent to amplitude arithmetic unit 50, and it produces the computer amplitude signal, this signal then is admitted to comparator 52, here signal is compared with the predetermined threshold value signal, takes this to form digital signal (1=has signal, the 0=no signal).This digital signal is fed into marginal detector 54, and triggering signal of its output shows that is just being jumped detecting of edge.

AGC

25% work period modulation needs the reception agc circuit of specific type, and it avoids following the tracks of when no signal exists.Therefore, use the AGC that promotes rapid fading slowly, it is shown among Fig. 6, here, received signal is fed to magnitude comparator spare 56, and it can adopt the structure of pre-programmed ROM, the amplitude signal that therefrom obtains is fed into comparator 58, and this signal and predetermined threshold subtract each other and obtain difference signal within it.Difference signal is fed into a low pass filter by one of two ratio multipliers 60 and 62, and it comprises an adder 64 and a lagging device 66 that is connected to loop 68, uses some in two multipliers according to the symbol of difference signal.If difference signal is finished slow fading for just in the AGC control signal.If difference signal is finished fast lifting for negative in the AGC control signal.The output of filter is to be fed to gain control unit 44(to be shown among Fig. 1) gain signal.

Approximate frequency is caught

Owing to need not carry out frequency acquisition at shut-in time (75% signal-less time (nulltime)) in 25% work period frame format, and because in the moment of carrying out frequency acquisition, frame regularly is unknown, will use the frequency acquisition circuit of an improved form, as shown in Figure 7, in this circuit, received signal is fed to discrete Fournier transform (DFT) arithmetic unit 70, its output high frequency band energy (energy that is higher than centre frequency) and low-frequency band energy (being lower than the energy of centre frequency).The output of high frequency band energy is subtracted each other on adder 72 with the output of low-frequency band energy, and its input is fed to a blender or multiplier 74.Also by a separator 74, it separates the symbol (negative or positive) of signal to the RF signal that receives, and takes this to determine the amplitude of symbol.Separation signal then is fed into filter 78, and it averages signal to handle and makes it level and smooth.Be fed to multiplier 74 from the output of filter 78 by amplifier 80.

Circuit 76,78 and 80 primary and foremost purpose are to prevent the effect of noise to output signal, and increase the weight of signal itself.In this respect, because noise has than small magnitude, in smoothing process, it can be effectively by filtering.On the other hand, because the common amplitude of useful signal is bigger, therefore level and smooth or filtering signal is added blender 74 signal is strengthened.

Leave blender 74 be conditioned signal on high and low-yield frequency by balanced, this equalizing signal is directly proportional with the short term average of received signal, it is fed into low pass filter, low pass filter is by adder 82, deferred mount 84 compositions, and by 86 closed loops of line.This deferred mount 84 presents than actual output signal 88 to the control of VCXO (VCXO) and is fed to the low pass filter output of any slightly in advance.VCXO control is to be used for the frequency of the interior master oscillator of regulating system.

After triggering or having proved effective synchronously, system enters idle voice mode, but can initial at any time speech work.If the receiver off-book of arbitrary end, the phone of the other end are with ring, up to sending an answer by telephone or former initial phone on-hook of ring.

Beginning by each voice time slot is set up calling by sound code word (VCW).This codeword table is the off hook state of initial station from tomorrow, and when this took place, this station of serving as the emulation base station was its off-hook notification central office (CO), to constitute and the connecting of central office.Initial subscriber station is dialled required number and is finished calling.When the on-hook of initiating station unit, the emulation base station by defendant VCM it, it provides on-hook and indicates to central office.

When the emulation base station is checked out bell signal from central office, make the subscriber unit ring by the corresponding VCW from the emulation base station, behind this subscriber unit off-hook, the emulation base station is accused it by corresponding VCW, then, it provides off-hook and indicates to central office.

The radio telephone system of the above-mentioned type is configured among Fig. 8 and illustrates for example, in the drawings, shown subscriber unit 90 by antenna 92 and 94 and emulation base station 96 carry out wireless telecommunications.Base station 96 carries out wire communication by circuit 98 and interface 100 with central office.

The two-way custom system

Said system can be equipped with the two-way user and use, as shown in Figure 9.In this system, each channel can provide two all-pass words, and does not need two-way switch.In this point, two-way subscriber unit 102 links to each other with 110 with a pair of substation 108 with 106 by line 104.Subscriber unit 102 by antenna 112 and 114 and emulation two-way base station 116 carry out wireless telecommunications.Unit 116 is connected with central office with 120 by circuit 118.

Two different users 108 and 110 utilize time slot arrangement, as above-mentioned be numbered 4675863 patents disclosed, specify separately time slot wherein for each user.The frame structure of this arrangement is shown among Figure 10, illustrates on figure and is numbered 1,2, four time slots of 3 and 4.Preceding two time slots are used for the emulation base station, and latter two is used for two users.

Synchronous by what all emulation base stations were sent, a plurality of two-way custom systems can be operated on the different channels.The frame structure that this kind mode is described is shown among Figure 11, and channel 1 is illustrated among the figure, and what channel n(n represented channel wherein needs number arbitrarily) be illustrated in down.In each channel, preceding two time slots are used for sending, and latter two is used for receiving.

The call remote service

An emulation base station can be served a plurality of different users at synchronization, in this arranges, (it introduces to see before and states patent subscriber station in detail in order to receive the transmission of monitoring wireless control channel (RCC) constantly, be numbered 4675863), call out certain specific user up to the emulation base station by customer identification number (SID).Receive after the calling that the user utilizes above-mentioned synchronizing process to begin to send to emulation base station back.Call out for starting, the user only sends on RCC with aforesaid synchronizing process.

Function for monitoring

Native system can be used for monitoring one or more functions, in this regard, uses a computer as control or data recording equipment, a plurality of users can periodically be inquired after, so that some projects are reported, for example, temperature, weather conditions, fail safe, water or flood alarm, the low fuel alarm, remote gas, ammeter or meter reading, or the like.This is shown among Figure 12, and emulation base station 122 carries out wireless telecommunications with a plurality of users that are denoted as 124,126 and 128.Unit 122 all links to each other with the computer or the data terminal 132 that are used for the data input with the phone 130 that is used for speech communication with circuit.Similarly, each subscriber unit links to each other with separately phone 134,136 or 138, being used for speech communication, and links to each other with separately data equipment.

The relay station system

An important use of the present invention is as the scope of relay station with expanding system.Under this arrangement, the emulation base station can be used for overcoming and stops interference, for example mountain peak or similar object, and Figure 13 illustrates this kind function, it illustrates a subscriber unit 146 and the wireless telecommunications that are positioned at the emulation base station 148 at top, mountain peak.Unit 148 also carries out wireless telecommunications with the standard base station 150 that is connected with central office.

Fairly simple and cheap emulation base station is very worthwhile as the relay station unit.No matter clear is arranged, it can be used as the long distance range that relay station comes expanding system.By utilizing the arrangement of time slot, do not use any two-way switch just can make the relay station unit enter whole system rightly, and maintain the standard base station and user's the transparency.Certainly, also can between user and another emulation base station, assign emulation base station rather than standard base station.Come the scope of expanding system greatly in not expensive mode, can use multistage mode from an emulation base station to another emulation base station.This is shown among Figure 14, and among the figure, a series of relay stations unit 152 is assigned between user 154 and the base station 156.

Except the scope of expanding system, the relay station unit also is used for removing actual base station signal again before the user sends by equilibrium.

A relay station also can be used for being referred to as the starlike system of relay station, to drive relay station and/or user.This is shown among Figure 15, in the drawings, single relay station unit 158 and dependent repeater station 160 and 162 and one or more user, for example 164, carry out communication.Dependent repeater station self again with the user, as 166,168,170,172,174, and other dependent repeater station,, carry out communication as 176.Any one dependent repeater station, for example relay station 162, can be used as the last relay station that carries out direct communication with the base station that is marked as 178.

A plurality of relay stations are positioned in the three unities, their channel difference, but by synchronously.Therefore can send simultaneously and receive, take this to avoid using duplexer.In such structure, a major relay station is used to monitor the RCC channel of base station, and the RCC by the emulation base station postpones the information that is monitored to each user, in this structure, and on call setup, the designated relay station channel of each user.

Claims (7)

1, a kind of wireless digital telephone system comprises:

An emulation base station and at least one subscriber station with the mutual communication of radiofrequency signal, wherein said radiofrequency signal comprises the waveform that is divided into a plurality of time frames, every frame comprises at least two time slots, be used for the single time slot that each sends comprising one, described each station all can send on same frequency and receive, the mutual time frame of emulation base station and subscriber station is synchronous, and except this emulation base station provides synchronizing signal and described subscriber station has acquisition equipment to adjust its time frame according to described synchronizing signal, the described station is similar;

Control device in each station;

Controlling of each station, by comparing with a predetermined threshold value signal to monitor from the amplitude of the signal of another station and to determine just jumping in the waveform of this signal amplitude monitoring arrangement from the amplitude of each signal of another station along the position by described control device;

Each station by the control of described control device in order to adjust frame in it regularly so that frame is harmonized is just jumping along the framing control device that the position occurs;

Described emulation base station has the frame synchronization trigger equipment, and has described subscriber station to have the timing and the synchronous frequency acquisition device of timing that is triggered by the emulation base station of will receive from the signal of described emulation base station;

The main difference of described emulation base station and subscriber station only is that described emulation base station has described synchronous triggering device;

Described system comprises that is also avoided fast automatic gain control (AGC) circuit that rises of the slow fading of searching for when no signal, and described agc circuit comprises:

Received signal is by feed-in in it and export the magnitude operating device of an amplitude signal;

One receives described amplitude signal and it is deducted from a predetermined threshold to obtain the comparator of a difference signal;

Be used for determining that thereby the symbol of described difference signal is for just or for negative selectively finishing slow fading or the fast device that rises at the AGC signal; And

Be used for this signal of finishing dealing with is fed to the device of described control device.

2, wireless digital telephone system as claimed in claim 1 is characterized in that, described frequency acquisition device comprises:

The Signal Separation that will receive from described emulation base station is the arithmetic unit of high frequency band and low-frequency band energy frequency;

This high frequency band energy output is deducted to obtain the device of a consequential signal from this low-frequency band energy output;

The symbol of this consequential signal is separated only to determine the device of its amplitude;

When filter out noise, strengthen the device of this separated signal; And

The signal that this is separated is fed to the device that VCXO (VCXO) regularly is provided at described other station.

3, wireless digital telephone system as claimed in claim 2 is characterized in that, described arithmetic unit is a discrete Fournier transform (DFT) device.

4, wireless digital telephone system as claimed in claim 2 is characterized in that, described emulation base station and central office communication.

5, wireless digital telephone system as claimed in claim 2 is characterized in that, has at least two subscriber stations and this time frame and comprises four independently time slots.

6, wireless digital telephone system as claimed in claim 2 is characterized in that, described emulation base station and the wireless telecommunications of a series of similar emulation base station, last emulation base station in this series and subscriber station wireless telecommunications.

7, wireless digital telephone system as claimed in claim 2 is characterized in that, this channel has plural assigned timeslot.

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