JPH02241138A - Transmission timing latch system - Google Patents

Abstract

PURPOSE:To latch a transmission timing of a slave station to an optimum state at all times even when environmental change or a secular change in a component characteristic takes place without incurring the deterioration in the transmission efficiency or expensive equipment by applying prescribed transmission timing acquisition control after the operation start of each slave station. CONSTITUTION:A control section 20 is provided with a phase shift information transmission control means 20a used when the transmission timing of a slave station BB is acquired, bit deviation information transmission control means 20b and timing latch control means 20c in addition to the control means relating usual data transmission, and the timing latch control means 20c operates the phase shift information transmission control means 20a and the bit deviation information transmission control means 20b periodically for all the operating slave stations BB to correct the transmission timing of the slave stations BB. Thus, the transmission timing of the slave stations BB is latched to an optimum state at all times even when environmental change or secular change in the component characteristic take place without incurring the deterioration in the transmission efficiency or expensive equipment.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Field of Industrial Application) The present invention provides a time division multiple access wireless communication system that performs wireless communication between one master station and a plurality of slave stations using burst signals. The present invention relates to a transmission timing holding method for holding the transmission timing of a slave station so as not to overlap with the transmission timing of other slave stations.

(Prior Art) In recent years, with the development of communication technology and the diversification of communication needs, various communication systems have been developed, including time division multiple access (TDMA).
There is a wireless communication system that adopts the nMultiple Access) method. FIG. 9 shows an example of the configuration, and this system is composed of one master station A and a plurality of slave stations B1 to Bn arbitrarily distributed. Then, from the master station A to each slave station B1 to Bn, a time division multiplexed signal (TDM signal) consisting of continuous waves is sent, for example, as shown in FIG. As shown in the figure, each slave station B1 to Bn transmits a data signal consisting of a burst wave to the time slots TS1 to TSn assigned in advance to the master station A and each slave station B.
Data is mutually communicated between the terminals 1 to Bn.

By the way, in this type of system, since the distance between the master station A and each of the slave stations B1 to Bn differs for each slave station, a difference occurs in the propagation time of the radio signal. For this reason, each slave station B1 to B
In order to prevent the transmission signals from overlapping each other at the master station A, it is necessary to adjust the transmission timing for each slave station and set it to the optimum timing.

Therefore, conventionally, a control slot is provided in the TDMA signal transmitted from each slave station B1 to Bn to the master station A, as shown in FIG. 12, and when a slave station Bi is newly installed, the control slot A burst signal for adjustment is sent from slave station Bi to master station A using . Then, the master station A detects the amount of deviation from the regular reception timing of this adjustment burst signal, and converts the detection result of this deviation amount into the TDM signal (
Using the control slot shown in FIG. 10), the master station A notifies the slave station Bi and displays it on a display or the like. And slave station Bi
The transmission timing of the slave station Bi is adjusted by maintenance personnel manually operating switches according to the amount of deviation displayed on the display.

(Problem to be solved by the invention) However, in all conventional transmission timing acquisition methods, adjustments are made only when the slave station Bi is installed.
If the transmission timing of the slave station changes due to changes in the surrounding environmental conditions after adjustment or changes in circuit element characteristics over time, the system will continue to operate as is, and as a result, the time slots at the master station may not be mutually compatible. Signals from multiple slave stations adjacent to each other could overlap, leading to deterioration in line quality or, in the worst case, to line disconnection.

Additionally, in the past, in order to prevent the influence on the lines of other stations, guard pits were provided in each time slot TSI to TSn for data transmission, and these guard bits were sometimes used to absorb transmission timing shifts. . However, in general, guard bits cannot be set to a large value in consideration of transmission efficiency, so if there is a large shift in transmission timing, it cannot be absorbed by the guard pits, and deterioration in line quality is unavoidable. On the other hand, in order to minimize the above-mentioned transmission timing deviation, attempts have been made to construct the device to be less susceptible to temperature changes and to use circuit elements with excellent characteristics. However, doing so would result in major damage to the device, and since high-quality circuit elements would have to be used, the device would be extremely expensive.

Therefore, the present invention focuses on these circumstances, and without causing a decrease in transmission efficiency or an increase in the price of the device, the transmission timing of the slave station is always optimized even when changes in the surrounding environment or changes in element characteristics occur over time. The purpose of the present invention is to provide a transmission timing holding method that can maintain a stable state.

[Configuration of the Invention (Means for Solving the Problems) The present invention provides a time division multiple access wireless communication system that performs wireless communication between one master station and a plurality of slave stations using burst signals. A timing acquisition signal is sent to the master station within the control slot provided in the transmission frame, and the master station detects the amount of deviation in the reception timing of this timing acquisition signal from the regular reception timing and uses the detection result as Notify the corresponding information to the slave station that sent the timing capture signal, and adjust and set the transmission timing of the own station in accordance with the information notified from the master station in this slave station so as to make the amount of deviation zero. The transmission timing acquisition control operation is performed for each slave station periodically or irregularly after the slave station starts operating.

(Function) As a result, according to the present invention, even if the surrounding environmental conditions change or the element characteristics change over time after the transmission timing is captured,
Changes in transmission timing caused by this are corrected by a transmission timing acquisition control operation that is performed periodically or irregularly as necessary, so that the transmission timing of the slave station is always maintained at an optimal value. Therefore, signals of adjacent time slots do not overlap in the master station, thereby making it possible to maintain high transmission quality. In addition, it is not necessary to set the width of the guard bit large, and it is possible to reduce the width of the guard bit, so transmission efficiency can be increased accordingly. Furthermore, the device can be structured to be less susceptible to temperature changes, and the width of the guard bit can be made smaller. Since there is no need to use superior circuit elements, it is possible to prevent the device from becoming complicated, large, and expensive.

(Embodiment) FIG. 1 shows the configuration of a master station and a slave station to which a transmission timing holding method is applied in an embodiment of the present invention. In addition, in the figure, only one of the plurality of slave stations is shown for convenience of explanation.

First, the master station AA has a wireless line termination device 10, a modem device 11 that modulates and demodulates transmitted and received signals, a wireless transmitter/receiver device 13 having an antenna 12, an input operation section such as a key switch, and an output display section such as a display device. Console 14
It is equipped with

Of these, the wireless line terminal device 10 includes a multiplexing section 15 and a demultiplexing section 16 that multiplex transmit signals and demultiplex the received TDMA ('Q signal), and a signal It has a plurality of interfaces 17 connected via a bus, and these interfaces 1
7 are connected to terminal devices 19 via lines 18, respectively. The wireless line terminal device 10 also includes a control section 20 and a nonvolatile memory 21 made of, for example, an E2 FROM. The control section 20 has, for example, a microcomputer as a main control section, and in addition to the control means related to the normal pig transmission operation, the control section 20 also has a phase shift information transmission control means 2 used when capturing the transmission timing of the slave station BB.
0a, bit deviation information sending control means 20b, and timing holding control means 20c.

When setting the transmission timing of the slave station BB, the phase shift information transmission control means 20a issues an instruction to the slave station BB to adjust the phase shift of the transmission timing, and then adjusts the phase difference sent from the slave station BB. The phase shift information of the adjustment burst signal is notified to the slave station BH, and the slave station BB is made to adjust the phase of the transmission timing. After the phase shift information transmission control means 20a has finished adjusting the phase shift, the bit shift information transmission control means 20b transmits the bit shift information to the slave station B.
It issues an instruction to B to adjust the bit shift, and then notifies slave station BH of the bit shift information of the burst signal for bit shift adjustment sent from slave station BB, and instructs slave station BB to adjust the transmission timing. This is done bit by bit. Incidentally, the phase shift of the burst signal for phase adjustment and the bit shift of the burst signal for bit shift adjustment are respectively detected by shift detection means 16a provided in the separating section 16.

The timing holding control means 20c periodically transmits the phase shift information transmission control means 2 to all the slave stations in operation.
0a and the bit deviation information sending side control means 20b are operated to correct the transmission timing of each slave station.

Figure 2 shows the TDM sent from the master station AA to the slave station BB.
This shows the frame structure of the signal. As shown in Figure (a), this TDM signal has a control slot arranged between the synchronization bit F and a plurality of data transmission time slots TSI to TSn. A timing adjustment control signal is sent using a portion of the control slot. This timing adjustment control signal is composed of bits for inserting the identification number ID of the slave station, instruction information C0NT to the slave station, phase shift information, bit shift information, and preliminary information, as shown in FIG. 2(b). In addition, (C) in the same figure shows the configuration of time slots TSI to TSn for pig transmission, where F is a synchronization bit, ID is a slave station identification number, SV is a maintenance bit, H is data, and P is a parity bit. are shown respectively.

On the other hand, slave station BB also includes a radio line termination device 30, a modem device 31, a radio transmitter/receiver device 33 having an antenna 32, and a console 34, like the master station AA. Of these, the radio line termination device 30 includes a multiplexing section 35 that multiplexes transmission data and control signals, a demultiplexing section 36 that separates a signal addressed to the local station from the TDM signal sent from the master station AA, and a demultiplexing section 36 that multiplexes transmission data and control signals. It has a plurality of interfaces 37 connected to the section 35 and the separation section 36 via signal buses, and these interfaces 37 are connected to the line 3.
Terminal devices 39 are respectively connected via 8. Further, the wireless line terminal device 30 and the control unit 40, for example, the E2
It has a nonvolatile memory 41 made of FROM and a transmission timing variable section 42, respectively. First of all, the transmission timing variable section 42 includes a phase shift circuit 42a that varies the transmission phase of the transmission signal, and a bit delay circuit 42b that varies the transmission timing of the transmission signal bit by bit.

The control unit 40 has, for example, a microcomputer as a main control unit, and in addition to control means related to normal transmission and reception operations, it also includes phase shift adjustment control means 40a used when capturing transmission timing, and bit shift adjustment. control means 40b. The phase shift adjustment control means 40a operates when a phase adjustment instruction is sent from the master station AA,
A phase adjustment burst signal is sent to the master station AA using the control slot of the TDMA frame, and when phase shift information is sent from the master station AA, the phase shift circuit 42a responds to this information. This is to variably control the amount of phase shift. The bit deviation adjustment control means 40b operates when a bit deviation adjustment instruction is sent from the master station AA.
A burst signal for bit adjustment is sent to A using the control slot of the TDMA frame, and in response, the master station
When bit shift information is sent from A, the amount of delay of the bit delay circuit 42b is variably controlled in accordance with this information.

FIG. 3 shows the frame structure of the TDMA signal transmitted from each slave station configured as above to the master station AA.
This signal is transmitted to the control slot AQ as shown in FIG.
is placed at the beginning, followed by time slots TSI to TSn for data transmission. Then, a part of the control slot AQ is used to selectively send out a phase adjustment burst signal and a bit adjustment burst signal. The burst signal for phase adjustment is shown in the same figure (b).
As shown in the figure, it consists of a repeating signal of "10" (36 bits). Further, the bit adjustment burst signal is composed of a predetermined synchronization pattern (SYNC pattern) and the identification number ID of the slave station, as shown in FIG. 3(c). Note that (d) in the same figure shows the configuration of the data transmission time slots TSI to TSn, where G is the guard bit ζ, ID is the identification number of the slave station, Sv is the maintenance bit, H is the data, and P is the parity bit. are shown respectively.

Next, the transmission timing holding method of this embodiment will be explained based on the above configuration. Note that the description will be made on the assumption that the transmission timing of each slave station in operation has already been set to an optimal value by initial timing acquisition at the time of installation.

The control unit 20 of the master station AA monitors the operating time of each slave station in operation. In this state, if, for example, a certain period of time (for example, several minutes) has elapsed since the operation time of the slave station BB was initially acquired after the initial capture of the transmission timing, the control unit 20 of the master station AA controls the maintenance of the transmission timing for the slave station BB. Start. That is, the control unit 20 of the master station AA first creates a timing adjustment control signal for adjusting the phase shift. Figure 4 shows its configuration, in which the ID number of the slave station BH is inserted into the LD number bit, and the first bit of the 4-bit instruction information, that is, the adjustment type bit, corresponds to the phase adjustment instruction. At the same time, set the final bit of the instruction information, that is, the adjustment start and end bit, to “0” corresponding to the adjustment start instruction.
This control signal is inserted into the control slot of the TDM signal by the multiplexer 15 and sent to the slave station BB. At this time, control signals and data addressed to the existing slave stations are multiplexed and sent out in other areas of the control slot of the TDM signal and in each of the time slots TSI to TSn for data transmission.

On the other hand, the control unit 40 of the slave station BB monitors the arrival of the timing adjustment control signal addressed to the own station while performing normal data transmission/reception control, and in this state, the control unit 40 of the slave station BB performs timing adjustment from the master station AA to the own station. When a control signal is sent, the content of the instruction from the master station AA is first recognized from the instruction information of this control signal. Since the phase adjustment instruction bit is now "0", it is recognized that the instruction is for phase adjustment, and thereafter control for phase shift adjustment is started. That is, first, at the transmission timing currently set in the transmission timing variable section 42, the phase adjustment burst 1m shown in FIG.
The signal is inserted into the control slot AQ of the TDMA frame and transmitted.

On the other hand, after transmitting the timing adjustment control signal, the master station AA determines the regular reception timing from the reception timing of the phase adjustment burst signal inserted into the control slot of the TDMA signal arriving from the slave station BB. The phase shift amount with respect to the reception timing is detected by the shift detection means 16a. If a phase shift is now detected, the control unit 2° calculates a phase correction value from this phase shift amount, and uses this phase correction value as the phase shift information of the timing adjustment control signal shown in FIG. 2(b). Insert it into the slave station BB
Send it towards. For example, if the reception timing of the phase adjustment burst signal (a) is delayed by 5/20 bits compared to the regular reception timing (b) as shown in FIG. 5, the transmission phase of the slave station BB is 5/20 bits. Since it is necessary to advance the phase by one bit, the control section 20 sends a phase correction value of "r-5/20 bits" to the slave station BB. The phase shift information is expressed in 8 bits as shown in Fig. 2(b), and the first bit represents - or 10, and the remaining 7 bits represent m/20. Therefore, in this case, the phase correction value rloooololJ is sent to slave station BB.

When the phase correction value addressed to the own station is sent from the master station AA, the control unit 40 of the slave station BB adds the above correction value -5/20 bits to the current set value of the phase shift amount, and controls the phase shift circuit. The phase shift amount of 42a is corrected to the above addition result.

Thus, the transmission phase of the slave station BH is adjusted so that the phase difference with respect to the reference phase at the master station AA becomes zero.

Note that after this phase correction, slave station BB sends the phase adjustment burst signal again to master station AA with the phase after the above correction. In contrast, when the phase correction value is sent again from the master station AA, the phase shift amount of the phase shift circuit 42a is readjusted according to this phase correction value, and from then on the phase difference of the master station AA becomes zero. Repeat the above operations until.

Now, when the phase difference becomes zero by the above phase adjustment, the master station AA rewrites the phase shift amount stored in the nonvolatile memory 21 into the new phase shift amount set in the slave station BB by the above phase adjustment. Then, as shown in FIG. 6, the adjustment type bit of the 4-bit instruction information is set to "1" corresponding to the bit adjustment instruction, and this control signal is sent to the slave station BB. On the other hand, when the control signal instructing the above-mentioned bit adjustment arrives from the master station AA, the slave station BB determines that the phase adjustment has been completed, and first stores it in the non-volatile memory 41 similarly to the above-mentioned master station AA. The old phase shift amount is rewritten to the new phase shift amount, and then control for bit adjustment is started. That is, first, the control unit 40 generates a bit adjustment burst signal consisting of a predetermined synchronization pattern and the ID number of its own station as shown in FIG. The multiplexer 35 inserts the data and sends it to the master station AA.

Then, when the bit adjustment burst signal arrives from the slave station BB, the master station AA detects the amount of bit deviation from the synchronization pattern reception timing with respect to the normal reception timing using the deviation detection means 16a of the separating section 6. If a bit shift is detected now, the control unit 2o calculates a bit shift correction value to make this bit shift amount zero, and uses this correction value as the timing adjustment control signal shown in FIG. 2(b). It is inserted into the bit deviation information bit of BB and sent to the slave station BB. For example, as shown in FIG. 7, the bit adjustment burst signal reception timing (a
) is 9 bits earlier than the normal reception timing (b), the transmission timing of the slave station BB needs to be delayed by 9 bits, so the control unit 20 sets the bit correction value of "+9 bits" to the slave station. Send to BB. The bit shift information is also expressed in 8 bits like the phase shift information, and the first bit represents 10, and the remaining 7 bits represent the amount of bit shift, so in this case A bit correction value roooooloolJ is sent to the slave station BB.

On the other hand, when the slave station BB receives the bit correction value (+9 bits) addressed to it from the master station AA, it starts the bit delay circuit 4.
The delay amount of 2b is further delayed by 9 bits from the current setting value. Therefore, the transmission timing of the slave station BB is the same as that of the master station AA.
The bit deviation is adjusted to zero with respect to the reference timing. The slave station BB then sends out the bit adjustment burst signal again to the master station AA at the transmission timing after this bit shift correction. On the other hand, when the master station AA confirms that there is no bit shift from the reception timing of the bit adjustment bust signal retransmitted from the slave station BB, the master station AA confirms that the old bit delay amount stored in the non-volatile memory 2] is rewritten to the new bit delay amount set in the slave station BB, and the adjustment start and end bit of the instruction information of the timing adjustment control signal is set to "1" corresponding to the adjustment end instruction, as shown in FIG. and sends it to slave station BB.

Then, the slave station BB will set the adjustment start/end bit to '1'.
”, it is recognized that the transmission timing adjustment has been completed, and the old setting value in the nonvolatile memory 41 is rewritten to the new delay amount set in the bit delay circuit 42b, and from then on, data is processed according to this newly set transmission timing. Resume sending.

In this way, the transmission timing of slave station BB is corrected to an optimal value. Note that the transmission timing of the slave station BB will be periodically corrected in accordance with the adjustment procedure described above every time the predetermined period of time (for example, several minutes) elapses.

Furthermore, the master station AA also corrects the transmission timing of other slave stations in operation at regular intervals, as in the case of the slave station BB.

In this example, the transmitting and evening signals of each slave station are corrected periodically during operation, so that even if changes in the surrounding environmental conditions or secular changes in element characteristics occur during operation, However, the transmission timing can be corrected and always maintained at the optimal value without leaving it in a state where it is shifted. Therefore, in the master station AA, signals do not overlap between adjacent time slots, and high quality data transmission can always be performed. In addition, since there is no need to set the guard bit width large, transmission efficiency can be maintained high, and there is no need to structure the device to reduce the effects of temperature changes or use high-quality circuit elements. Since there is no , the device can be made simple and inexpensive.

Note that the present invention is not limited to the above embodiments. For example, if the phase shift or bit shift of the signal sent from the slave station does not become zero or does not change even after repeating the phase adjustment or bit adjustment procedure a predetermined number of times, the master station may adjust the transmission timing of the slave station. It is also possible to determine that correction is impossible and generate an abnormality detection signal, thereby causing the slave station to stop transmitting. In this way, the slave station will not continue transmitting signals with the transmission timing shifted, and as a result, it is possible to prevent a problem in which the data transmission time slot interferes with the data transmission of other slave stations adjacent to each other. I can do it. Further, although the above embodiment did not specifically mention the initial acquisition method of transmission timing when installing a slave station, this initial acquisition method uses the method of regularly correcting the transmission timing described in detail in the embodiment. Alternatively, other schemes such as those described in the prior art may be used. Further, in the embodiment described above, the transmission timing is corrected periodically, but it may be corrected non-regularly as necessary. In addition, the configurations of the master station and slave stations, the transmission timing adjustment control procedure and control content, the configuration of each signal, etc. can be modified in various ways without departing from the gist of the present invention.

[Effects of the Invention] As detailed above, according to the present invention, a timing acquisition signal is sent from a slave station to a master station within a control slot provided in a transmission frame, and the master station transmits a signal for timing acquisition. The amount of deviation of the signal reception timing from the normal reception timing is detected and the information corresponding to the detection result is notified to the slave station that sent out the timing capture signal, and the slave station receives the above notification from the master station. By performing the transmission timing acquisition control operation, which adjusts and sets the transmission timing of the own station according to the information in order to make the above-mentioned deviation amount zero, for each slave station either regularly or irregularly after the slave station starts operating. , we developed a transmission timing maintenance method that can maintain the transmission timing of slave stations in an optimal state at all times, even when changes in the surrounding environment or changes in element characteristics occur over time, without reducing transmission efficiency or increasing the cost of equipment. can be provided.

[Brief explanation of drawings]

1 to 8 are for explaining the transmission timing holding method in one embodiment of the present invention. FIG. 1 is a functional block diagram showing the configuration of a master station and a slave station to which the method is applied, and FIG. Figure 2 is a configuration diagram of the TDM signal sent from the master station to the slave station, Figure 3 is a configuration diagram of the TDMA signal transmitted from the slave station to the master station, and Figures 4 to 8 are used to explain the operation. The signal configuration diagrams, FIGS. 9 to 12, are used to explain the prior art. FIG. 9 is a schematic configuration diagram of a time division multiple access wireless communication system, and FIG. 10 is a frame configuration diagram of a TDM signal.
FIG. 1 is a timing diagram showing the transmission form of each slave station, and FIG. 12 is a frame configuration diagram of a TDMA signal. AA...Master station, BB...Slave station, 10.30...Radio line termination device, 11.31...Modulation/demodulation device, 12゜3
2... Antenna, 13.33... Radio transmitting/receiving device,
14.34... Console, 15.35... Multiplexing unit, 16.36... Separating unit, 16a... Displacement detection means, 17.37... Interface, 18.38...
・Line, 19.39...Terminal device, 20.40...
Control unit, 20a... Phase shift information transmission control means, 20
b... Bit deviation information sending control means, 20c... Timing holding control means, 40a... Phase deviation adjustment control means, 40b... Bit deviation adjustment control means, 21.4
DESCRIPTION OF SYMBOLS 1...Nonvolatile memory, 42...Transmission timing variable part, 42a...Phase shift circuit, 42b...Bit delay circuit.

Claims (1)

[Scope of Claims] In a time division multiple access wireless communication system that performs wireless communication using burst signals between one master station and a plurality of slave stations, a control system provided in a transmission frame from the slave station to the master station; A timing acquisition signal is transmitted within the slot, the master station detects the amount of deviation of the reception timing of this timing acquisition signal from the regular reception timing, and transmits information corresponding to the detection result to the timing acquisition signal. A transmission timing acquisition control operation is performed for each slave station to notify the slave station, and the slave station adjusts and sets the transmission timing of its own station in order to make the deviation amount zero according to the information notified from the master station. A transmission timing maintenance method characterized in that the transmission timing is maintained periodically or irregularly after the start of operation of a slave station.