WO2001099330A1

WO2001099330A1 - Method for synchronising the transmitting and receiving modes of transmitters and receivers in a telecommunications network for carrying out this method

Info

Publication number: WO2001099330A1
Application number: PCT/DE2001/001375
Authority: WO
Inventors: Jörg ARNOLD
Original assignee: Ip2H Ag
Priority date: 2000-06-19
Filing date: 2001-04-09
Publication date: 2001-12-27
Also published as: AU6202901A

Abstract

The invention relates to a method for synchronising the transmitting and receiving modes of transmitters and receivers in a telecommunications network. The method is characterised by the following steps, with a view to providing universal synchronisation of the transmitting and receiving modes, especially within decentralized telecommunications networks: transmitting signal pulses with a predeterminable and identical width and clock-pulse rate, by means of at least one transmitter; setting a given time t0 during the transmission of the signal pulses by the at least one transmitter, by means of at least one receiver; forming receiving time windows of predeterminable and standardized or identical width and with a clock-pulse rate that is identical to the signal pulses, starting from the t0, by means of the at least one receiver; establishing a time t1 for at least one signal maximum of the total signal consisting of the signal pulses of the transmitter or resulting from the added signal pulses of the transmitters within a predeterminable period of time from the time t0, by means of the at least one receiver, in a receiving time window; and transmitting signal pulses of the width and clock-pulse rate of the original transmitters by means of the at least one receiver. A signal pulse is essentially transmitted at a time that is shifted by the time DELTA t = t1 t0 in relation to the clock-pulse rate of the receiving time window, so that the sequence of signal pulses that is generated by the at least one receiver is transmitted essentially synchronously or in time with the sequence of signal pulses of the original transmitter or the original transmitters essentially forming the signal maximum. The invention also relates to a telecommunications network for carrying out the method.

Description

METHOD FOR SYNCHRONIZING THE TRANSMITTER AND RECEIVER OPERATION OF TRANSMITTERS AND RECEIVERS IN A TELECOMMUNICATIONS NETWORK AND TELECOMMUNICATIONS NETWORK

FOR IMPLEMENTING THE PROCEDURE

The invention relates to a method for synchronizing the transmission and reception operation of transmitters and receivers in a telecommunications network. Furthermore, the invention relates to a telecommunications network, in particular a radio network, the transmitter and receiver being designed to carry out the above method.

Methods of the type mentioned at the outset and corresponding telecommunications networks are known from practice. For the operation of a telecommunications network, it is advantageous if the transmitters and the receivers of the network can communicate with one another at precisely the right time. Then telecommunication connection subscribers can define and use precise transmission and reception times at which other non-connection transmitters do not transmit and thus do not disturb the receiver or connection under consideration. For this purpose, the times of the beginning and the end of transmission transmissions must be determined jointly or synchronously by all transmitters and receivers involved in the telecommunications network.

Up to now, this necessary synchronization has taken place in that all transmitters and receivers use a common time or clock time, according to which they align and determine their transmission and reception transmission times. The synchronization clock used, which can use one or more point-in-time signal transmitters, is therefore regarded as a central facility of the telecommunications network.

This method has the disadvantage that such a central clock must be available or maintained and operated for a synchronized telecommunications network. In addition, there is the further disadvantage that when using central clocks, the transmitters and receivers that connect to each other have their exact ones mutual position or mutual distance must be known in order to be able to take into account or compensate for the necessary time shift of the synchronization signals due to a delay in the transmission time.

As a result, decentralized telecommunication networks that are supposed to get by without central facilities, or networks in which the individual subscribers do not know the exact distance to their connection partners, cannot be synchronized by means of central clocks.

The present invention is therefore based on the object of specifying a method and a telecommunications network of the type mentioned at the outset, according to which a universal synchronization of the transmission and reception mode, in particular within the framework of decentralized telecommunications networks, is made possible.

According to the invention, the above object is achieved by a method with the features of patent claim 1 and by a telecommunications network with the features of patent claim 17. The method according to the invention then has the following steps: transmission of signal pulses with predeterminable and identical width and clock rate by at least one transmitter; Setting any point in time t ₀ - during the transmission of the signal pulses by the at least one transmitter - by at least one receiver; Formation of reception time windows - with predeterminable and standardized or identical width and with a clock rate identical to the signal pulses - from time t ₀ by the at least one receiver; Determining a point in time ^ of a signal maximum of the total signal consisting of the signal pulses of the transmitter or of the added signal pulses of the transmitters in a predeterminable period of time from time t ₀ by the at least one receiver in a reception window; Sending signal pulses of the width and clock rate of the original transmitter by the at least one receiver, wherein a signal pulse is transmitted essentially at a time shifted by the time Δt = t, -1 ₀ relative to the clock rate of the reception time window, so that the by the at least a receiver generated signal pulse train is sent substantially synchronously or in time with the signal pulse train of the original transmitter or transmitters. In the method according to the invention, at least one transmitter first sends signal pulses with a predefinable and identical width and a predefinable and identical clock rate. In most cases, however, several transmitters send such signal pulses, and the transmission can still be random and unsynchronized.

In the next step, at least one receiver sets an arbitrary point in time t ₀ , this setting taking place during the transmission of the signal pulses by the at least one transmitter or a plurality of transmitters. This time t ₀ applies to the recipient or recipients as a time reference point for the further process.

The at least one receiver now forms reception time windows from time t ₀ , the reception time windows having a predeterminable and standardized or identical width and a clock rate identical to the signal pulses of the transmitters. This defines the position of the reception time window relative to time t ₀ . The at least one receiver now shifts the reception time window.

Next, the at least one receiver determines a point in time ^ starting from the point in time t ₀ at which a signal maximum occurs in a reception time window. The signal maximum belongs to the total signal, which consists of the signal impulses of the transmitter or the added signal impulses of the transmitters - if several transmitters are present. A predeterminable time period tt _{0 is selected} from time t ₀ . In other words, a signal maximum is determined from an overall signal, which is composed of the superimposition of the signal pulses sent by the transmitter. As mentioned above, the transmitters sent signal pulses with a predefinable and identical width and clock rate. Depending on the progress of the synchronization, the signal pulses are sent more or less synchronously. Here there is a superimposition of the signal pulses to form the overall signal. This total signal is at a maximum when several transmitters are already transmitting approximately synchronously. Time t is then assigned to such a signal maximum. The formation of the sequence of reception time windows makes it possible, as it were, to scan a predefinable time period from time t ₀ . The reception time window sequence therefore does not have to start at time t ₀ , but can also be specified in a predefinable manner relative to time t ₀ be postponed. With such a shift, however, it must be ensured that signal pulses from one transmitter or several transmitters can be received by one or more receivers.

In the last method step, the at least one receiver now sends signal pulses with the width and clock rate of the original signals of the original transmitter. However, an arbitrary signal pulse is sent essentially at a point in time that is shifted by the time Δt = tt ₀ relative to the clock rate of the reception time window. This ensures that the original receiver is virtually synchronized with the group of transmitters that have essentially formed the signal maximum. The signal pulse sequence generated by the at least one receiver is transmitted essentially synchronously or in time with the signal pulse sequence of the original transmitter or the original transmitter, which essentially forms the signal maximum.

In the method according to the invention, a receiver quasi listens to the point in time at which most transmitters or a majority of the transmitters transmit a signal pulse or signal pulses. These transmitters, which transmit essentially at the same time, transmit quasi-synchronously. Accordingly, the receiver virtually attaches itself to these transmitters in order to increase the number of synchronously transmitting transmitters or synchronized transmitters and receivers.

If the method of this type is repeated several times by several receivers, there is a kind of self-synchronization or auto-synchronization of the respective receiver. As a result, the level of synchronization across the entire telecommunications network increases. The process can be carried out with different receivers until the entire telecommunication network works in sync.

No central network elements are required in the method according to the invention. Furthermore, it is also not necessary to know the exact distance between the transmitters and receivers, since differences in transit time of signals due to different distances between the transmitters and receivers are taken into account almost automatically when carrying out the method. In the step of dividing the time t. considerable how the exact distance of the transmitter and receiver is to each other, since only one signal maximum is essential for the receiver.

Consequently, the method according to the invention enables universal synchronization of the transmission and reception operation, in particular within the framework of decentralized telecommunication networks.

At this point it should be pointed out that the term “width” is to be understood in the context of peaks, signal pulses or windows in the sense of time width or time duration within the entire present description of the invention.

In an advantageous embodiment of the method, the signal pulses could be sent on a predefinable synchronization channel. This would avoid signal overlap or signal superimposition with, for example, a data signal to be transmitted.

The transmission and reception of the signal pulses could take place from any transmitter and / or receiver at predeterminable or randomly selected time intervals. It is only essential that the signal pulses are sent at a time when at least one receiver can receive such signal pulses.

Analogously, each transmitter and / or receiver could send and receive according to predefinable or randomly selected time intervals. In other words, a signal pulse train could be sent for a period of time and then a pause could be made until the signal pulse train was sent again. The frequency of sending and receiving such signal pulse sequences and their length is to be based on the respective application. The optimal procedure can be determined for the respective application, i. H. a procedure in which the synchronization z. B. is done as quickly as possible.

With regard to the fastest possible synchronization, at least one of the transmitters could also become the receiver once and at least one of the Sometimes the receiver becomes a sender. In this case, a change from a transmitter to the receiver and a receiver to the transmitter could take place at random.

The width of the reception time window could essentially correspond to the width of the transmitted signal pulses. In view of the best possible signal resolution, the width of the reception time window could also be chosen to be as small as possible.

With a view to a particularly reliable determination of the point in time t of a signal maximum, the receiver or the receivers could vary the timing of the reception time window. This also ensures a particularly rapid determination of the point in time ti.

Also with regard to a particularly reliable determination of the time t ₁ , the predeterminable period of time from the time t _{0 could} comprise at least one complete period of the signal pulse sequence sent by the at least one transmitter. Otherwise the determination of the time ^ could fail.

With regard to a particularly reliable determination of the point in time t, each receiver could determine the course of the overall signal within the period and preferably store it. This enables a particularly precise analysis of the received signals.

The signal maximum that is determined at time t could be an absolute maximum in the period under investigation. However, even a relative maximum could justify an improved degree of synchronization.

Depending on the application, the signal maximum could be determined in a predeterminable time interval. With regard to a particularly secure and effective synchronization, the transmission of signal pulses could take place over several periods. This would ensure a particularly reliable reception of the signal pulses by the receiver. The received signal, which is dependent on the variation in the timing of the reception time window, consists of the chronologically following areas of individual transmitter contributions with different transmission times and with different distances from the receiver under consideration. The contributions from different broadcasting distances and from different broadcasting times can overlap. Overall, a signal curve with a stochastic envelope curve is to be expected, which shows a sequence of relative maxima and minima.

As soon as the receivers have determined the center line timing or center of the absolute maximum or maximum of their possibly variation-dependent reception signal and the peak width of the reception signal maximum and switch back to the transmitter group, they set the transmission time for their synchronization signals or signal pulses according to the measured center line position and start to send the synchronization signals or signal pulses. As a result, the maximum is adjusted.

Since, with a statistically assumed homogeneous distribution or constant areal density of the telecommunication network participants, the number of all participants with a similar distance around the receiver under consideration increases quadratically with increasing radius around the receiver, but the signal power contributions of the participants decrease quadratically with increasing distance from the receiver, one will if necessary, a variation-dependent reception signal curve with a constant plateau or a more symmetrical reception signal curve is expected.

The transmission time is advanced or advanced exactly by half the peak or plateau width - starting from the center line. As a result, the transmission time of the receiver under consideration coincides with the transmission times of the largest group of telecommunication network subscribers with a similar average distance to the receiver under consideration within the time window. As the process progresses, all receivers look for the time of transmission of this largest group of transmitters and join this group in alternating transmission mode. All other groups of stations with different time positions are progressively reduced. After a certain time or after a certain number of changes in transmission mode and reception mode, the variation-dependent reception signal swings up to form a resonance curve, the width of which is only formed by the transmitter signal contributions at the same transmission time from a different distance from the receiver. The essential process steps here are determining the peak or plateau width of the signal maximum and advancing the transmission time from the center of the signal maximum - the point in time t - by half the peak or plateau width.

The width of the resonance curve then only reflects the signal transit time range or the size of the surface area under consideration. The area is the area of all transmitters whose signals can be heard at the receiver location under consideration. The smaller the area of the transmitter-receiver ensemble, the sharper or narrower this resonance curve. In the limit case of infinite signal propagation speed or the spatial contraction of the contraction area to a point, the resonance curve approaches a Kronecker delta function, whereby the contraction area is to be understood as the spatial area within which all synchronized transmitters and receivers can still receive each other. The half-width of the resonance curve then reflects the blurring of the transmission time.

The procedure according to the invention takes into account or compensates for the influence of the signal transit time on the synchronization. The transmission time window width or the transmission pulse length of the signal pulses on the synchronization channel is advantageously set equal to the reception time window width in order to achieve a maximum resolution of the telecommunications network subscriber groups with a similar distance from the receiver.

In the actual transmission / reception mode for useful information in the non-synchronization channels, the reception time window can be set to be delayed or advanced, starting from the trigger time, in order to, for example, B. only to choose the contact with transmitters a defined distance from the receiver under consideration. The position of the reception time window or the retardation or advancement ΔT = ΔS / c represents the distance ratio ΔS on the signal transmission path, where c is the signal propagation speed.

Conversely, the receivers can determine or determine the distance of the connection neighbors from the shift .DELTA.T - the desired retardation or advancement - the received signal timing at the trigger time. If three neighbors know their mutual distance within a contraction area, they form a basis from which every radio connection distance can be measured automatically, provided that two connected network users know the distance to at least one common neighbor that lies in the intersection of their contraction areas. If, after a certain operating time, all network participants know the distances to their nearest neighbors, the network is completely measured and the absolute geometric positions of the network participants can be calculated from this data from a central point. The radio operation of this synchronization method according to the invention represents a terrestrially supported “ground positioning system”.

The invention guarantees convergence at a single common clock time within an area or contraction area in which all transmitters audible to the receiver are contained, even if there is initially a stochastic temporal distribution of clock times of the individual transmitters. After a certain time, the telecommunications network automatically and completely synchronized itself without a central control. The transit times of the transmitter signals are taken into account by the synchronization method according to the invention.

There is an auto-synchronization or an auto-synchronization method. A synchronization precision of a few microseconds can be achieved with this method according to the invention. The limitation lies in the finite propagation speed of the radio signals in contraction areas, for example, which are spatially extended up to 1 km. For a distance of 1km, an electromagnetic pulse takes about 3.33 microseconds to run. In a manner according to the invention, a telecommunications network, in particular a radio network, is also specified, the transmitter and receiver being designed to carry out the method according to the invention.

In particular, the transmitters and receivers can determine their mutual distances and / or positions by measuring the signal transit times when shifting their reception time window. A terrestrial ground positioning system is formed by the operation of the telecommunications network.

In summary, it should be noted that the invention enables the synchronized transmission and reception operation in completely decentralized organized telecommunication networks and in telecommunication networks in which the exact position or the mutual distance between connection participants is not known. The invention enables the construction of such telecommunication networks. The invention further enables the precise measurement or the position determination of the network subscriber distances or the network subscribers.

The invention can be used, for example, in the context of a radio network. In principle, however, it can also be used in other types of telecommunications networks, such as landline networks.

The invention advantageously uses a synchronization channel. Each transmitter or receiver sends or receives on the synchronization channel at certain, for example stochastically selected, time intervals for a certain, for example stochastically selected, time period with a preferably predetermined common clock rate, synchronization pulses with a standard pulse length and a standard transmission power. The telecommunications network subscribers in operation fall into two groups. One group sends synchronization signals and the other group receives synchronization signals. The individual participants can switch to one or the other group alternately for a certain random period of time. The frequency of these connections could be set in such a way that the telecommunication network area becomes coherent in terms of synchronization, ie that each network area area is synchronized with every other. All subscribers who are in operation and receive the signal pulses can vary the timing of a reception time window, for example "scan" or "wobble", and measure their reception power, for example. B. on the synchronization channel in the reception time window. The participants can determine the time position of the "scan-dependent" maximum reception power. The width of the reception time window can be standardized or possibly minimized in favor of the best possible signal resolution.

There are now various possibilities for advantageously designing and developing the teaching of the present invention. For this purpose, reference is made to the subordinate claims, on the one hand, and to the following explanation of the method according to the invention with reference to the drawing. In connection with the explanation of the method according to the invention with reference to the drawing, generally preferred refinements and developments of the teaching are also explained. Show in the drawing

1 shows a schematic representation of the timing of the reception time window relative to the transmitter signal pulses, three different situations being shown here,

2 in a diagram the reception power relative to the reception time window variation and

3 shows the development of the reception power as a function of the reception time window variation in a diagram.

In Fig. 1, the relative timing of the reception time window to the transmitter signal pulses is shown in a schematic representation. Three situations are shown, the middle situation showing the greatest overlap between reception time windows and transmitter signal pulses. The first and the third situation show time-shifted and thus unsynchronized time slots. The size of the blackened areas shows the degree of synchronization. 2 shows the received power P as a function of the received time window variation Δt in a diagram. At time Δ ^ there is extensive synchronization. The blackened areas in the diagram correspond to the blackened areas in FIG. 1.

3 shows the development of the reception power P as a function of the variation in the reception time window and thus the adaptation of the signal pulses of the transmitters originally working as receivers. Three stages of the synchronization development are shown, stage 1 with the solid line showing an initial stage. Level 2, which is shown by short dashes, represents a medium synchronization state and stage 3, which is represented by large dashes, shows a high degree of synchronization in the form of a narrow and high peak with no secondary maxima as in the case of stages 1 and 2.

In stage 1 there is a largely unsynchronized state, here two maxima have developed purely by chance, which point to two groups of participants that are synchronized to a certain extent relative to one another. In the case of stage 2, the synchronization method has already had an effect, to the extent that the higher maximum of stage 1 has further increased and the lower maximum of stage 1 has reduced. At level 3, the synchronization process has progressed so far that there is only a high maximum. The original second group of slightly synchronized transmitters has completely disappeared and joined the first group with the higher maximum.

The method according to the invention is an auto-synchronization method in which the subscribers in a telecommunication network synchronize successively by repeatedly using the method.

With regard to further advantageous embodiments of the method according to the invention, reference is made to the general part of the description and to the appended claims in order to avoid repetition.

Claims

Patent claims

1.Procedure for the synchronization of the transmission and reception of transmitters and receivers in a telecommunication network, the following steps are necessary:

- Sending signal pulses with a predetermined and identical width and clock rate by at least one transmitter;

- Setting any time t ₀ - while the signal pulses are being sent by the at least one transmitter - by at least one receiver;

- Formation of reception time windows - with predeterminable and standardized or identical width and with a clock rate identical to the signal pulses - from time t ₀ by the at least one receiver;

- Determining a time t, a signal maximum of the total signal consisting of the signal pulses from the transmitter or from the added signal pulses of the transmitters in a predeterminable period of time from time t ₀ by the at least one receiver in a reception time window; and

- Sending signal pulses of the width and clock rate of the original transmitter by the at least one receiver, wherein a signal pulse is transmitted essentially at a time shifted by the time Δt = t ₁ - t ₀ relative to the clock rate of the reception time window, so that the time signal transmitted by the at least one receiver generated signal pulse sequence is transmitted essentially synchronously or in time with the signal pulse sequence of the original transmitter or the original transmitter which essentially forms the signal maximum.

2. The method according to claim 1, characterized in that the signal pulses are sent on a predetermined synchronization channel.

3. The method according to claim 1 or 2, characterized in that each transmitter and / or receiver sends and receives at predeterminable or randomly selected time intervals.

4. The method according to any one of claims 1 to 3, characterized in that each transmitter and / or receiver sends and receives after predeterminable or randomly selected time intervals.

5. The method according to any one of claims 1 to 4, characterized in that at least one of the transmitters also becomes the receiver once and that at least one of the receivers also becomes the transmitter once.

6. The method according to claim 5, characterized in that the change of a transmitter to the receiver and a receiver to the transmitter takes place randomly.

7. The method according to any one of claims 1 to 6, characterized in that the width of the reception time window substantially corresponds to the width of the transmitted signal pulses.

8. The method according to any one of claims 1 to 6, characterized in that the width of the reception time window is chosen to be as small as possible.

9. The method according to any one of claims 1 to 8, characterized in that the receiver or receivers vary or vary the timing of the reception time window for determining the time t of a signal maximum.

10. The method according to any one of claims 1 to 9, characterized in that the predefinable period comprises at least one complete period of the signal pulse sequence sent by the at least one transmitter.

11. The method according to any one of claims 1 to 10, characterized in that each receiver determines the course of the total signal within the period and preferably stores it.

12. The method according to any one of claims 1 to 11, characterized in that the signal maximum is an absolute maximum in the period under investigation.

13. The method according to any one of claims 1 to 12, characterized in that the signal maximum is determined in a predetermined time interval.

14. The method according to any one of claims 1 to 13, characterized in that the transmission of signal pulses takes place over several periods.

15. The method according to any one of claims 1 to 14, characterized in that the peak width of the signal maximum is determined.

16. The method according to any one of claims 1 to 15, characterized in that the transmission time from the center of the signal maximum - the time t, - is brought forward by half the peak width or delayed.

17. Telecommunication network, in particular radio network, transmitter and receiver being designed to carry out the method according to one of claims 1 to 16.

18. Telecommunications network according to claim 17, characterized in that the transmitters and receivers determine their mutual distances and / or positions by measuring the signal propagation times when shifting their reception time window.

19. Telecommunication network according to claim 18, characterized in that a terrestrially supported "Ground Positioning System" is formed by the operation of the telecommunication network.