JP3328176B2 - Buffer and handover trunk - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buffer for sequentially reading out transmission units such as cells and packets provided from a single or a plurality of routes in a node device, and a mobile communication system to which this buffer is applied. The present invention relates to a handover trunk that switches a communication path in a switching system according to handover.

[0002]

2. Description of the Related Art In recent years, advanced digital transmission technology and information processing technology have been applied to mobile communication systems. With the spread of terminals in accordance with the liberalization of the market, not only voice information but also images, digital information and other information have been developed. There is a strong demand for high-speed transmission services of various information.

[0003] Therefore, as for the switching system of the next-generation mobile communication system, research and development are being advanced with respect to the application of ATM which can flexibly adapt to the transmission of various information described above. FIG. 5 is a diagram illustrating a configuration example of a mobile communication system to which ATM is applied. In the figure, a mobile station 72 is located in any of the wireless zones formed by a plurality of wireless base stations 71-1 to 71-N,
1-N are wired transmission lines 73-1 to ATM to which ATM is applied, respectively.
It is connected to the corresponding route of the mobile switching center 74 via 73-N.

In the mobile switching center 74, the above-described plurality of wired transmission lines 73-1 to 73-N are connected to corresponding ports of a switch 75 (hereinafter, referred to as "wireless-side ports"), and the switch 75 is connected. The handover trunk 76 is connected to a specific port (for the sake of simplicity, it is assumed that there are three ports different from the wireless side ports). The switch 75 and the handover trunk 76
A processor (CPU) via each communication link 77
It is connected to 78 communication ports. In the following, for simplicity, it is assumed that the switch 75 is configured as a multistage switch including a pair of distributed networks and a routing network disposed between the distributed networks.

[0005] In the handover trunk 76, two of the above specific ports are connected to corresponding inputs of a selector 79, and a communication link 77 is connected to a selection input of the selector 79. The output of the selector 79 is connected to the write input of the buffer memory 80, and the read output of the buffer memory 80 is output from the specific ports described above, which are different from the two ports described above, and the input of the cell reception determination unit 81. And connected to. Cell reception determining section 8
One output of the timer 82 is connected to a start input of the timer 82, and one output of the timer 82 is connected to a reset input of the timer 82 via a cell loss determining unit 83. The other outputs of the cell reception discriminating unit 81 and the timer 82 are respectively connected to corresponding inputs of the delay amount varying unit 84, and the output of the delay amount varying unit 84 is supplied to one of the timing control units 86 via the correction value storage unit 85. Connected to the input of The other input of the timing controller 86 includes a physical timing generator 87
The output of the timing control unit 86 is connected to the control input of the buffer memory 80.

In the conventional example having such a configuration, the processor 78 and the radio base stations 71-1 to 71-N cooperate with each other based on the procedure of call processing and channel setting, for example, the radio base station 71-1. , 71-N, the mobile station 72 located at the point where the radio zones overlap each other, seizes the handover trunk 76 and controls the switch 75 via the communication link 77 to perform the handover. A communication path is formed between the three ports to which the trunk 76 is connected, the communication partner, and the wired transmission paths 73-1 and 73-N.

[0007] Also, the mobile station 72 sends a signal to the radio base station 71-1.
The communication signal (which may be voice or data) wirelessly transmitted to (71-N) is transmitted quality (indicating the received electric field strength and the degree of intersymbol interference) and the timing shown in FIG. Information (the time at which the wire transmission path 73-1 (73-N) is determined as the optimum correction value α according to the type of call and the like based on a field test and the like and should be read from the buffer memory 80 (the radio base station 71 -1 (71-N) + α).) Is converted to a “cell column” consisting of a set of cells to which “+” is added. Further, these “cell rows” are provided in parallel to the handover trunk 76 via the wired transmission paths 73-1 and 73-N and the above-described communication paths.

In the handover trunk 76, under the control of the processor 78, the correction value storage unit 85 holds the correction value α optimal for the completed call. Further, the physical timing generation section 87 gives the physical timing P which is sequentially updated to the timing control section 86. Further, the selector 79 selects one “cell row” having high transmission quality for each individual cell (or a plurality of cells) from among the “cell rows” described above, and selects the selected “cell row”. The cells provided as "columns" are sequentially stored in the buffer memory 80.

[0009] The cell reception discriminating section 81 includes a buffer memory 8
When the time point at which the cells stored in 0 are to be read at a predetermined cycle is recognized, the buffer memory 8
0 (corresponding cell) (sum of physical timing P described above and increment (= β−α) of correction value stored in correction value storage unit 85 with respect to initial value α (= P + (β−α)) ) Is stored (FIG. 7 (1)), and if the result of the determination is true,
The cell is read and given to the corresponding port of the switch 75. Therefore, the cell read out in this manner is transmitted to the above-mentioned call partner via the switch 75.

However, if the result of the above determination is false, the cell reception determination section 81 starts a timer 82 (FIG. 7 (2)). The timer 82 sets an interval of a value at which it is possible to determine that the “corresponding cell” has been lost for some reason with a desired accuracy, and when the timer 82 is activated as described above, the timer 82 measures the time over the interval. Do. During the period in which the timer 82 is counting the time in this manner, the cell reception determining unit 81 determines the above-mentioned “corresponding cell” and any cell following the cell (hereinafter, referred to as a “subsequent cell”). Is one of the buffer memory 8
It is determined whether it is written to 0 (FIG. 7 (3)). Further, when the “corresponding cell” is written in the buffer memory 80 during the period when the timer 82 is counting the time, the delay amount variable unit 84 reads the value t of the timer 82 at this time (FIG. 7). (4)) and an updated value β of the correction value is calculated based on the equation β = β + t, and the updated value β
Is stored in the correction value storage unit 85 (FIG. 7 (5)).

However, if the "subsequent cell" described above is written into the buffer memory 80 during the period when the timer 82 is counting the time, the cell reception determining unit 81 sets the value of the timer 82 to the final value ( It is set to the value to be taken at the end of the timing (FIG. 7 (6)). When the timer performed by the timer 82 continues to reach the final value, or when the cell reception determining unit 81 sets the final value as described above, and the time measurement ends, the cell loss determination unit 83 reads “the above-described“ The corresponding cell was lost. "
2 is initialized.

On the other hand, the timing control unit 86 controls the physical timing P given by the physical timing generation unit 87.
The sum (= P + (β−α)) of the correction value stored in the correction value storage unit 85 and the increment (= β−α) with respect to the initial value α is given to the buffer memory 80. The buffer memory 80 sequentially reads out cells containing timing information equal to the sum of the previously stored cells and supplies the readout cells to the switch 75.

That is, among the cells provided in parallel via the wired transmission lines 73-1 and 73-N, one of the cells having high transmission quality is in a state where the correction value has not been updated from the initial value α at all. Then, as shown in FIG. 8A, when the physical timing P becomes equal to the timing information n, the buffer memory 8
It is read from 0. However, for example, when the mobile station 72 performs a handover between the radio zones formed by the radio base stations 71-1 (71-N), and the propagation delay time of the transmission section to the handover trunk 76 becomes longer. As shown in FIG. 8B, the timing information n, the physical timing P, and the increment of the correction value (= β−α)
Is read out from the buffer memory 80 in the same manner when the sum of.

Therefore, the number of cells to be transmitted changes according to the increase or decrease of the information amount of the call signal, or the time required for the call signal to reach the handover trunk 76 changes according to the handover. Fluctuation caused by intermittent transmission of control cells based on a communication procedure in a section is absorbed via the buffer memory 80.

[0015]

By the way, in the above-mentioned conventional example, when detecting that the cells are discarded in the wired transmission lines 73-1 to 73-N, the cells stored in the buffer memory 80 are transmitted. For example, in order to be able to be surely performed before a similar point in time to arrive at the point in time and to be given a row of cells in parallel via the wired transmission lines 73-1 to 73-N, for example, Similar detection in the case of significant congestion cannot be realized unless additional circuits individually corresponding to these wired transmission paths 73-1 to 73-N are provided.

The reason why cells containing desired timing information are not stored in the buffer memory 80 is that the propagation delay of the wired transmission lines 73-1 to 73-N, the discard of cells performed in the preceding transmission section, and the like. In order to accurately determine which of these wired transmission paths 73-1 to 73
In the same way as -N, an additional circuit with a more complicated configuration was required.

However, even though these additional circuits can be realized by a known technique, they are inherently large in scale. Therefore, a system having a complicated zone configuration and a large scale has mounting technology, thermal design and other restrictions. And it was difficult to apply. Note that the above-described correction value can be set to a large value adapted to the maximum transmission delay time that can actually occur,
Such a correction value is not actually applied because it is not suitable for a call that requires real-time characteristics such as a voice-based call.

An object of the present invention is to provide a buffer and a handover trunk which can flexibly adapt to the configuration of a transmission line and the form of maintenance and operation without complicating the hardware configuration, and which can absorb fluctuations with high accuracy. With the goal.

[0019]

FIG. 1 is a block diagram showing the principle of the first to fourth aspects of the present invention.

According to the first aspect of the present invention, individual transmission units provided via a transmission path and sequentially including timing information indicating a time to be transmitted to a subsequent transmission section are sequentially fetched, and the timing A storage unit 11 that stores information in the order of information, a storage unit 12 that holds a correction value β that is used to replace timing information individually included in transmission units stored by the storage unit 11, and is read from the storage unit 11. Physical timing generating means 1 for generating a physical timing P which is a reference for selecting a power transmission unit
3, the timing information n included in each of the transmission units captured by the storage unit 11, the latest physical timing P generated by the physical timing generation unit 13, and the increment of the correction value held in the storage unit 12 ( β-
α), and when the former is smaller than the latter, the correction value updating means 14 for updating the correction value β to a value equal to or more than (P−n), and the transmission unit stored by the storage means 11 , A timing control means 15 for identifying a time point to be read based on the physical timing P generated by the physical timing generation means 13, and a timing control means 15 which is generated by the physical timing generation means 13 for each time point identified by the timing control means 15. The transmission in which the timing information n included in the transmission unit stored in the storage unit 11 is equal to or more than (P + (β−α)) with respect to the physical timing P and the correction value β held in the storage unit 12. A reading unit 16 for sequentially reading out units.

According to a second aspect of the present invention, there is provided the buffer according to the first aspect, further comprising a transmission unit accumulation determining means for determining whether or not any transmission unit is stored in the storage means. The updating means 14 has means for initializing the correction value β held in the storage means 12 when the result of the judgment made by the transmission unit accumulation judging means 21 is false.

According to a third aspect of the present invention, in the buffer according to the first aspect, the timing information n included in the transmission unit stored first in the transmission units stored in the storage unit 11 is obtained. The timing information acquiring unit 31 and the correction value updating unit 14 cause the reading unit 16 to read all the transmission units to be read at each time point identified by the timing control unit 15 from the transmission units stored in the storage unit 11. After that, the timing information n obtained by the timing information obtaining means 31 and the physical timing P generated by the physical timing generating means 13 are stored in a value β shown by an inequality β ≧ (P−n). A means for updating the correction value β held in the means 12.

According to a fourth aspect of the present invention, in the buffer according to the first aspect, the timing information n included in the transmission unit stored first in the transmission units stored in the storage unit 11 is obtained. A timing information acquisition unit 31; and a missing transmission unit detecting unit 3 that identifies a preceding transmission unit closest to the missing transmission unit among the transmission units stored in the storage unit 11 based on a sequence of timing information individually included.
The correction value updating unit 14 stores the transmission unit specified by the missing transmission unit detecting unit 32 out of the transmission units stored in the storage unit 11 when the reading unit 16 reads the transmission unit. Comparing the difference between the maximum value n _old and the minimum value n _new of the timing information included in the transmission unit stored in the means 11 with a preset threshold value,
When the former exceeds the latter, the physical timing generation means 1
3 for the physical timing P generated by
-N _new (where β ≧ α) is characterized by having a means for updating the correction value β held in the storage means 12 to a value represented by the equation of β ≧ α.

FIG. 2 is a block diagram showing the principle of the present invention. According to a fifth aspect of the present invention, in a plurality of transmission unit columns provided in parallel from a plurality of transmission paths via a communication path and including timing information indicating a time to be transmitted to a subsequent transmission section. Selecting means for selecting a single transmission unit specified based on a channel control procedure related to handover; and selecting means selected by the selecting means according to any one of claims 1 to 4, And a buffer 42 for sequentially transmitting the read transmission unit to a subsequent section of the communication path.

In the buffer according to the first aspect of the present invention, the physical timing generator 13 generates the physical timing P. The storage unit 11 fetches individual transmission units provided via the transmission path and including timing information, and stores them in the order of the timing information. In addition, the storage unit 12 holds a correction value β used for reading the timing information for these stored transmission units.
Further, the correction value updating means 14 calculates the timing information n, the latest physical timing P generated by the timing generation means 13 and the correction value held in the storage means 12 for each transmission unit fetched by the storage means 11. Is compared with the sum (β−α), and when the former falls below the latter, the correction value β is updated to a value equal to or more than (P−n).

On the other hand, the timing control means 15 identifies a time point at which the transmission unit stored by the storage means 11 should be read out based on the physical timing P generated by the physical timing generation means 13. At the time point identified in this way, the reading unit 16 sets the physical timing P generated by the physical timing generation unit 13 and the correction value held in the storage unit 12 out of the transmission units stored in the storage unit 11. With respect to the increment (β−α), the transmission units whose timing information n is equal to or more than (P + (β−α)) are sequentially read.

That is, the above-mentioned correction value β is stored in the storage means 1
1, the correction value is updated when the transmission unit stored in the storage unit 11 is read out, as in the conventional example, or is discarded in the preceding transmission section. The fluctuation can be absorbed with high accuracy without performing the processing of determining whether or not the fluctuation has been performed.

In the buffer according to the second aspect of the present invention, in the buffer according to the first aspect, the transmission unit accumulation determining means determines whether or not any transmission unit is stored in the storage means. The correction value updating means 14 initializes the correction value β held in the storage means 12 when the result of the determination is false. That is, since the correction value β is initialized in a state where there is no transmission unit to be read from the storage unit 11, it is avoided that the correction value β is updated only in the increasing direction, and the storage unit 11 is not updated.
The transmission unit stored in the memory is reliably read out while flexibly adapting to traffic concentration even when the word length of the timing information is small.

In the buffer according to the third aspect of the present invention, in the buffer according to the first aspect, the timing information acquiring means 31 includes the transmission information stored first in the transmission units stored in the storage means 11. The timing information n included in the unit is obtained. The correction value updating unit 14 is a unit that controls the timing control unit 1 among the transmission units stored in the storage unit 11.
After the reading unit 16 has read all of the transmission units to be read at each time point identified by No. 5, the timing information n obtained by the timing information obtaining unit 31 and the physical timing P generated by the physical timing generation unit 13 The correction value β held in the storage means 12 is set to a value β that satisfies the inequality β ≧ (P−n) with respect to
To update.

That is, even if the traffic continues to such an extent that the storage unit 11 does not become empty, the correction value β is set to a small value that ensures the timing at which the transmission unit stored in the storage unit 11 should be read. Since the buffer is appropriately updated, the buffer according to the second aspect enables more flexible adaptation to traffic distribution. According to the buffer according to the fourth aspect of the present invention, in the buffer according to the first aspect, the timing information acquiring unit 31 includes:
The timing information n included in the transmission unit stored first among the transmission units stored in 1 is acquired. The missing transmission unit detecting means 32 identifies the preceding transmission unit closest to the missing transmission unit from the transmission units thus accumulated, based on the sequence of timing information individually included in these transmission units. . Further, when the transmission unit specified by the missing transmission unit detection unit 32 among the transmission units stored in the storage unit 11 is read by the reading unit 16, the correction value updating unit 14 stores the correction unit in the storage unit 11. The difference between the maximum value n _old and the minimum value n _new of the timing information included in the accumulated transmission unit is compared with a preset threshold value. When the former exceeds the latter, the timing information is generated by the physical timing generator 13. Physical timing P
Then, the correction value β stored in the storage unit 12 is updated to a value represented by the equation β = P−n _new (where β ≧ α).

That is, when the number of transmission units stored in the storage means 11 following any missing transmission unit exceeds the above-mentioned threshold, the timing at which all of these transmission units should be read is secured. The correction value β is reduced as long as the correction value β is reduced, so that the frequency of updating in the direction in which the correction value β increases is suppressed to a desired small value according to the threshold value, and only in the direction in which the correction value β increases. An increase in the storage time that occurs in the storage unit 11 due to the updating is suppressed.

In the handover trunk according to the fifth aspect of the present invention, the selection means 41 is provided in parallel from a plurality of transmission paths via a communication path, and indicates a time to be transmitted to a subsequent transmission section. A single transmission unit specified from a plurality of transmission unit strings including timing information is selected based on a channel control procedure related to handover. The invention described in any one of claims 1 to 4 is applied to the buffer 42, a single transmission unit selected in this way is provided, and the read transmission unit is described above. The data is sequentially transmitted to the subsequent section of the communication path.

Therefore, in accordance with the configuration and arrangement of the wireless zone, the length and the length of the transmission path connecting the exchange in which the handover trunk according to the present invention is mounted and the wireless base station forming each wireless zone are determined. To adapt flexibly to
A communication path with high transmission quality is formed with high accuracy.

[0034]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 3 is a diagram showing an embodiment corresponding to the first to fifth aspects of the present invention. In the drawing, components having the same functions and configurations as those shown in FIG. 5 are denoted by the same reference numerals, and description thereof is omitted here. The difference between this embodiment and the conventional example shown in FIG. 5 is that a handover trunk 51 is provided instead of the handover trunk 76. Therefore, the mobile switching center will be denoted by the reference numeral “74a” for simplicity.

In the handover trunk 51, a selector 79 is provided at the first stage, and the output of the selector is connected to the inputs of the buffer memory 80 and the timing information extraction unit 53. The output of the buffer memory 80 is connected to the input of the timing information extraction unit 54 and the first input of the read control unit 55, and the output of the read control unit 55 is connected to the corresponding port of the switch 75. The output of the timing information extraction unit 53 is connected to one input of a correction value calculation unit 56, and the other input of the correction value calculation unit 56, the input of the timing control unit 52, and the second input of the read control unit 55 The output of the physical timing generator 87 is connected. The output of the timing control unit 52 is connected to the control input of the buffer memory 80, and the timing information extraction unit 54
Is connected to the third input of the read control unit 55. The input / output terminal of the correction value calculation unit 56 is a correction value storage unit 57
The output of the correction value storage unit 57 is connected to a fourth input of the read control unit 55.

The correspondence between the present embodiment and the block diagrams shown in FIG. 1 and FIG.
0 corresponds to the storage unit 11, the correction value storage unit 57 corresponds to the storage unit 12, the physical timing generation unit 87 corresponds to the physical timing generation unit 13, and the timing information extraction unit 5
3, 54 and the correction value calculation unit 56
, The timing generation unit 52 corresponds to the timing control unit 15, and the read control unit 55
, The timing information extracting unit 54 corresponds to the cell storage determining unit 21, the timing information acquiring unit 31, and the missing transmission unit detecting unit 32, and the selector 79 corresponds to the selecting unit 41.
, The buffer memory 80, the timing controller 5
2. The timing information extraction units 53 and 54, the read control unit 55, the correction value calculation unit 56, the correction value storage unit 57, and the physical timing generation unit 87 correspond to the buffer 42.

The operation of this embodiment according to the first and fifth aspects of the present invention will be described below. The call originating at the mobile station 72 is a completed call, and at the mobile switching center 74a,
Since the linking operation of each part in the process of forming a communication path via the switch 75 is the same as in the conventional example,
Here, the description is omitted. Handover trunk 5
In step 1, the correction value storage unit 57 holds an initial value α that is optimal for a corresponding call as a correction value β under the control of the processor 78.

The physical timing generator 87 generates a physical timing P. Further, the selector 79 determines the transmission quality for each cell (or a plurality of cells) of the two “cell columns” provided via the wired transmission paths 73-1 and 73-N as in the conventional example. One high cell is selected and provided to the timing information extraction unit 53, and is sequentially stored in the buffer memory 80.

The timing information extracting section 53 extracts timing information n included in the cell. Correction value calculation unit 5
6 reads the correction value β held in the correction value storage unit 57, and the inequality P + (β−α)> n holds for the correction value β, the timing information n and the physical timing P described above. It is determined whether or not (FIG. 4A). Further, when the result of the determination is true, the correction value calculation unit 56 sets the “read time equal to the value on the left side of this inequality to the time indicated by the timing information n included in the cell given from the selector 79. , The updated value of the correction value β is calculated by performing an arithmetic operation represented by the formula of β = P−n (a), and the updated value is calculated as a new correction value. It is stored in the correction value storage unit 57 as β (FIG. 4 (2)).

Further, the timing control section 52 controls the physical timing P given by the physical timing generation section 87.
, The time at which a subsequent cell is to be read from the buffer memory 80 is identified. At the time identified in this manner, the buffer memory 80 reads the cell stored first, and the timing information extraction unit 54 extracts the timing information included in the cell.

The read control unit 55 stores the timing information in the correction value β held in the correction value storage unit 57 and the physical timing P given by the physical timing generation unit 87.
And if no, no processing is performed if the result of the determination is false, but if the determination is true, all cells including this timing information are It is sequentially given to the corresponding port.

As described above, according to this embodiment, for the cells sequentially stored in the buffer memory 80, the correction value β is updated based on the individually included timing information, and the cells stored in the buffer memory 80 are updated. Among them, all the cells including the timing information adapted to the correction value β are sequentially given to the switch 75. Therefore, the amount of information of the call signal transmitted by the mobile station 72 increases or decreases, or the time required for the call signal to reach the handover trunk 51 changes according to the handover.
The fluctuation caused by the intermittent transmission of control cells based on the communication procedure in the ATM transmission section is determined by determining whether or not cells to be transmitted are stored in the buffer memory 80, The cell is absorbed without determining whether or not the cell has been lost in the preceding transmission section, and the scale of hardware can be reduced as compared with the conventional example.

Hereinafter, embodiments corresponding to the second to fourth aspects of the present invention will be described. This embodiment and claim 1,
The difference of the configuration from the embodiment corresponding to the invention described in FIG. 5 is that the timing information extracting unit 5 shown in FIG.
4 is that the monitoring output of No. 4 is connected to the corresponding input of the correction value calculating unit 56. Hereinafter, the operation of the present embodiment will be described.

The timing information extractor 54 determines whether or not any cells are stored in the buffer memory 80 (FIG. 4A), and provides the result of the determination to the correction value calculator 56. The correction value calculation unit 56 identifies the initial value of the correction value β held in the correction value storage unit 57, and if the result of the determination is true, the correction value calculation unit 56 according to claim 1 or 5, Processing similar to that of the embodiment corresponding to the invention is continued. However, when the result of the determination is false, the correction value calculation unit 56 updates the correction value β held in the correction value storage unit 57 to the above-described initial value (FIG. 4B).

As described above, according to the present embodiment, correction is performed in a state where no cells are stored in the buffer memory 80 (when all the cells stored in the buffer memory 80 are read by the read control unit 55). The value β is set to the initial value. Therefore, for example, when the amount of information of the call signal transmitted by the mobile station 72 decreases, or when the time required for the call signal to reach the handover trunk 76 in response to the handover decreases, an increase in fluctuation is allowed. As long as the amount of information and the required time are increased again, preparations for absorbing fluctuations caused by the increase in the information amount and the required time are performed promptly and reliably, and the time required for cells to be stored in the buffer memory 80 is reduced. The shortening increases the transmission efficiency.

In this embodiment, the buffer memory 8
The correction value β is set to the initial value when no cells are stored in 0. For example, the timing information extraction unit 54 determines the timing information n included in the earliest cell stored in the buffer memory 80. The value β is given to the correction value calculation unit 56 (FIG. 4A), and the timing information n and the physical timing P given by the physical timing generation unit 87 at that time are represented by a value β expressed by an inequality β ≧ P−n. The correction value calculation unit 56 may update the correction value (FIG. 4B).

As for the correction value β, the timing information extraction unit 53 (54) and the correction value calculation unit 56 work together, for example, to suppress the frequency of updating in the increasing direction to a desired small value. If the increase of the delay time due to the update of the correction value β only in the increasing direction should be suppressed, (1) missing in the transmission path,
Alternatively, a cell that is not intentionally transmitted from the transmitting end for the purpose of maintenance and operation is detected based on the timing information,
(2) By taking the difference between the timing information n _old contained in the oldest cell stored in the buffer memory 80 and the timing information n _new contained in the latest cell, the accumulated cell information Find the timing difference,
(3) When the timing difference exceeds a predetermined threshold value x (a value that prevents the correction value β based on the first aspect of the invention from being frequently and repeatedly performed), β = P-n _new (β ≧ α) can be reduced by performing the arithmetic operation.

As described above, the process of “detecting a cell that is missing on the transmission line or that has not been intentionally transmitted from the transmitting end for the purpose of maintenance and operation” is determined based on the physical timing P. Buffer memory 80
However, the present invention is not limited to the timing of reading, and may be performed, for example, after all cells to be transmitted at that timing are read from the buffer memory 80.

Further, in each of the above-described embodiments, the configuration and operation of the handover trunk to which the inventions of claims 1 to 4 are applied have been described. If the individual cells provided via the ATM include the above-mentioned timing information, the cells may be applied to any system and apparatus as a cell buffer for absorbing the fluctuation generated in the ATM transmission line.

In each of the embodiments described above, the multi-stage switch type switch 75 is applied, but the switch 75 may be configured as, for example, a shared memory type switch. Further, in each of the above-described embodiments, the field of the cell in which the timing information n is to be arranged is not shown at all.
It may be placed in either the payload or the header.

In each of the above-described embodiments, the buffer memory 80 accumulates the given cells in the order of the timing information, and the timing information extraction unit 53 updates the correction value and determines whether or not the update is necessary. Although the timing information is extracted, for example, the timing information extracting unit 53 may be configured as a part of the buffer memory 80. Further, in each of the above-described embodiments, the correction value β is updated based on the arithmetic operation shown in the above equation (a). For the correction value β, for example, the inequality β> P−n holds. It may be updated to a value.

[0053]

As described above, according to the first aspect of the present invention, the correction value is updated at the time when the transmission unit stored in the storage means is read out, or the processing for determining the presence or absence of the missing unit is not performed. In addition, fluctuations occurring in the transmission path are absorbed with high accuracy. Further, according to the second aspect of the invention, it is avoided that the correction value is updated only in the increasing direction,
The transmission unit stored in the storage means is reliably read out while flexibly adapting to traffic concentration even when the word length of the included timing information is small.

Further, according to the third aspect of the invention, it is possible to flexibly adapt to the traffic distribution as compared with the second aspect of the invention. In the invention according to claim 4,
The frequency at which the correction value β is updated in the increasing direction is suppressed to a desired small value according to the threshold value, and the increase in the accumulation time due to the update only in the direction in which the correction value β is increased is reduced. Is suppressed.

Further, according to the fifth aspect of the present invention, according to the configuration and arrangement of the radio zones, the length and the length of the transmission path connecting the exchange and the radio base station forming each radio zone are flexible. And a communication path with high transmission quality is formed with high accuracy. Therefore, in the transmission system to which these inventions are applied, high reliability and quality of service are maintained regardless of the configuration of the system and the form of maintenance and operation.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the principle of the present invention.

FIG. 2 is a principle block diagram of the invention according to claim 5;

FIG. 3 is a diagram showing an embodiment corresponding to the first to fifth aspects of the present invention.

FIG. 4 is a flowchart of a correction value update process according to the embodiment.

FIG. 5 is a diagram illustrating a configuration example of a mobile communication system to which ATM is applied.

FIG. 6 is a diagram showing timing information added to a cell.

FIG. 7 is a flowchart of a correction value update process in a conventional example.

FIG. 8 is a diagram illustrating the operation of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Accumulation means 12 Storage means 13 Physical timing generation means 14 Correction value update means 15 Timing control means 16 Reading means 21 Transmission unit accumulation discrimination means 31 Timing information acquisition means 32 Missing transmission unit detection means 41 Selection means 42 Buffer 51, 76 Handover trunk 52, 86 Timing control unit 53, 54 Timing information extraction unit 55 Read control unit 56 Correction value calculation unit 57, 85 Correction value storage unit 71 Wireless base station 72 Mobile station 73 Wired transmission path 74, 74a Mobile switching center 75 Switch 77 Communication link 78 Processor (CPU) 79 Selector 80 Buffer memory 81 Cell reception determination unit 82 Timer 83 Cell loss determination unit 84 Delay amount variable unit 87 Physical timing generation unit

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI H04Q 7/22 H04Q 11/04 304K 7/28 7/04 J 11/04 304 (72) Inventor Motoi Tamura Toranomon, Minato-ku, Tokyo JP-A 9-64892 (JP, A) JP-A 5-244186 (JP, A) JP-A 9-64 326804 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 12/56

Claims (5)

(57) [Claims] 1. Storage means for sequentially taking in individual transmission units provided via a transmission path and including timing information indicating a time to be transmitted to a subsequent transmission section, and accumulating the transmission units in the order of the timing information. Storage means for holding a correction value β for reading the timing information individually included in the transmission units stored by the storage means; and a physical unit which is a selection criterion of a transmission unit to be read from the storage means. Physical timing generation means for generating the timing P; timing information n included for each transmission unit taken in by the storage means; and the latest physical timing P generated by the physical timing generation means
And the sum of the correction value increment (β−α) held in the storage means, and when the former falls below the latter, the correction for updating the correction value β to a value equal to or more than (P−n). Value updating means; timing control means for identifying a time point to be read based on the physical timing P generated by the physical timing generation means for the transmission unit stored by the storage means; and identification by the timing control means. Every time
With respect to the physical timing P generated by the physical timing generation unit and the correction value β held in the storage unit, the timing information n included in the transmission unit stored in the storage unit is (P + (β -Α)) a buffer comprising: a reading unit for sequentially reading the transmission units described above. 2. The buffer according to claim 1, further comprising a transmission unit storage determining unit configured to determine whether any transmission unit is stored in the storage unit, wherein the correction value updating unit performs the transmission unit storage determination. When the result of the determination made by the means is false, the correction value β stored in the storage means
Characterized by comprising means for initializing a buffer. 3. The buffer according to claim 1, further comprising: timing information acquiring means for acquiring timing information n included in the transmission unit stored first among the transmission units stored in the storage means. The value updating unit is obtained by the timing information obtaining unit after the reading unit reads out all of the transmission units to be read at each time point identified by the timing control unit, out of the transmission units stored in the storage unit. Means for updating the correction value β held in the storage means to a value β expressed by an inequality of β ≧ (P−n) with respect to the obtained timing information n and the physical timing P generated by the physical timing generation means. A buffer comprising: 4. The buffer according to claim 1, wherein the transmission unit stored first in the transmission units stored in the storage unit.
Time to acquire timing information n included in transmission unit
Transmission information stored in the storage unit;
Time unit that includes the immediately preceding transmission unit that is closest to the unit
Transmission unit detection means for identifying based on a row of signaling information
Correction value updating means, the transmission unit stored in the storage means, the missing transmission
The transmission unit specified by the unit detection
When read by a stage, it is stored in its storage means.
Value n of the timing information included in the transmission unit
_old And the minimum value n _new And the preset threshold value
When the former exceeds the latter, the physical timing
Β with respect to the physical timing P generated by
= P-n _new(However, β≥α)
Means for updating the correction value β held in the storage means.
And a buffer. 5. A sequence related to handover among a plurality of transmission unit columns provided in parallel from a plurality of transmission paths via a communication path and including timing information indicating a time to be transmitted to a subsequent transmission section. 5. A selecting means for selecting a single transmission unit designated based on a procedure of channel control, and a single transmission as described in any one of claims 1 to 4 and selected by said selecting means. A handover trunk provided with a unit and a buffer for sequentially transmitting the read transmission unit to a subsequent section of the communication path.