JP3296384B2 - Time-division multiple access method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time division duplex communication (TD).
D: Time Division Duplex) and a time division multiple access method suitable for transmitting data and the like packetized by Time Division Duplex.

[0002]

2. Description of the Related Art Conventionally, T which is used for high-speed data communication is used.
A DMA (Time Division Multiple Access) frame is shown in FIG. 5A so that all slave stations can easily establish and maintain frame synchronization with the master station.
The frame length was fixed as shown in FIG.

In the case of the TDMA system in which the frame length is fixed, in order to cope with fluctuations in the amount of information, (1) a method in which the burst signal length is fixed and the number of transmissions per frame is increased or decreased in accordance with the amount of information; Alternatively, (2) TDM is performed by a method in which the number of burst signal transmissions per frame is fixed and the burst signal length is increased or decreased according to the amount of information.
An A frame was configured.

However, in the above method (1), if the burst signal length is set short, a preamble is required for each burst signal, so that the ratio of the overhead portion increases and the frame utilization efficiency is reduced. Was. Further, if the burst signal length is set to be long, one burst signal must be allocated to the minimum information, so that the empty area in the burst signal increases and the actual data transmission efficiency decreases. On the other hand, in the case of the method (2), since a plurality of burst signals of different lengths are packed in one frame, if short burst signals are intensively generated in one frame, the time domain in which no signal exists exists. And the frame utilization efficiency is reduced.

FIG. 5B shows another conventional example.
This is a case where the TDMA frame length is continuously adjusted according to the amount of information. In this case, it is possible to improve the frame use efficiency as compared with the case of the fixed length described above. However, since the start position is uncertain, it is necessary to use a frame synchronization pull-in circuit that is faster than the fixed-length case in order to detect the start of a frame. Therefore, in this case, there is a disadvantage that the synchronization pull-in circuit is complicated and expensive.

[0006]

As described above, according to the time division multiple access of the conventional TDMA system, there is a problem that it is not possible to improve the frame use efficiency and simplify the frame synchronization circuit. . The present invention has been made under such a background, and an object of the present invention is to provide a time division multiple access method capable of improving frame use efficiency without using a complicated frame synchronization circuit.

[0007]

According to the first aspect of the present invention,
In a time division multiple access method for transmitting information between a master station and one or more slave stations using frames by time division,
The frame is divided into the first, second, and third ranges.
And in the first range,
The slave station generates one or more slave stations from a plurality of frame lengths that are integral multiples of a predetermined shortest frame length.
Frame length longer than the time required to transmit the generated information volume
And one selection of requests to the master station, the third
In the range, the master station is earlier in the first range.
Serial 1 or more specified that the frame length before Symbol frame the frame length requested by the slave station, time division multiple access and performing for each transmission of the frame to the one or more slave stations Is the way.

[0008] Further, the invention according to claim 2 is characterized in that the master station and one or more other stations are connected to the master station.
Use time-divided frames for information with the above slave stations
In the time division multiple access method for transmitting
Is determined in advance according to the information amount of the information.
Within multiple frame lengths that are integer multiples of the short frame length
The master station selects one frame length from the
The specified frame length as the frame length of the frame
With respect to the one or more slave stations every time the frame is transmitted.
And the one or more slave stations communicate with the predetermined
Based on the frame length of the short, a division multiple access method when you characterized <br/> to perform the frame synchronization processing.

[0009]

[0010]

According to the above arrangement, time-division multiple access is performed using a frame having a length that is an integer multiple of the shortest frame length as a reference, without increasing the complexity of the frame synchronization circuit. A sub-optimal frame length can be selected according to a change in the amount of information, and frame utilization efficiency can be easily increased.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an example of a frame configuration in the time division multiple access method of the present invention. In this figure, 201-1, 202-1 and 203-1 are frame headers, 2
01-2, 202-2 and 203-2 are data bursts, 201-3, 202
-3 and 203-3 are frame tailors. Each slave station requests the master station to allocate a data burst using a frame header, and the master station instructs the slave station to allocate a data burst using a frame tailor. L represents the shortest frame length (time length). Note that each frame header 201-1, 2
The lengths of 02-1 and 203-1 are set to a fixed and equal length, and the lengths of the frame tailors 201-3, 202-3 and 203-3 are also set to a fixed and equal length.

In this case, the shortest frame having a frame length L is composed of a frame header 201-1, a data burst 201-2, and a frame tailor 201-3. Frame tailor 202-
The frame composed of 3 is a double-length frame, and the frame composed of the frame header 203-1, the data burst 203-2, and the frame tailor 203-3 is an m-length frame (where m is an integer of 2 or more). ).

In this case, the shortest frame length L is set to a minimum length of a packet, for example, in the case where data is packetized and transmitted in the mobile communication of the TDD system. It is set equal to the length of time plus the length.

Next, an algorithm for determining the frame length requested by the slave station to the master station when data to be sent to the slave station occurs will be described with reference to FIG. It is assumed here that a process starting from step 300 shown in FIG. In step 300, data to be sent to the master station (here, the data length is assumed to be mL; this data length m
L represents the longest frame length in this embodiment and is assumed to be a value of 4 or more. ) Occurs, the step
The process proceeds to 301, and it is determined whether the generated data length can be transmitted with the shortest frame length L. In this case, assuming that the length of the frame header 201-1 shown in FIG. 1 is α and the length of the frame tailor 201-3 is β, the length of the data burst 201-2 is obtained by L−α−β. So
If the generated data length is equal to or less than L-α-β, the determination result is “YES”, and the process proceeds to Step 306;
The result of the determination is "NO" and the operation proceeds to step 302. Here, since the data length mL is 4 L or more, the determination result is “NO”.
And proceed to step 302.

In step 302, it is determined whether or not the generated data length can be transmitted with a frame length of 2L. If the data length is equal to or less than 2L-α-β, the determination result is “YES”, and the flow proceeds to step 307. On the other hand, in other cases, the determination result is “NO”, and the same processing is repeatedly performed until step 303. in this case,
Since the data length mL is 4 L or more, the determination result is “NO”. Next, the same process is repeatedly executed thereafter, and the process proceeds to step 303.

In step 303, it is determined whether or not the generated data length can be transmitted with the frame length (m-1) L. If the data length is equal to or less than (m-1) L-α-β, the determination result is “YES” and the process proceeds to step 308.
On the other hand, in other cases, the determination result is “NO” and the process proceeds to step 309. Here, the data length mL is (m−
1) Since the length is longer than L-α-β, the determination result is “NO” and the flow proceeds to step 309.

In step 309, a control signal requesting the master station to set the frame length to mL is transmitted to the frame header (201-1, 2-2 in FIG. 1) of the frame next to the currently transmitted frame.
02-1 and 203-1). Next, the process proceeds to step 304.

In step 304, it is determined whether the generated data length can be transmitted with the longest frame length mL. If the data length is less than mL-α-β, the judgment result is “YES”
And a series of processing ends. On the other hand, in other cases, the determination result is “NO” and the process proceeds to step 305. Here, since the data length mL is longer than mL-α-β,
The result of the determination is "NO" and the routine proceeds to step 305.

In step 305, the data length of the data that cannot be transmitted with the requested frame length mL determined this time is obtained according to the data length- (mL-α-β) formula, and is set as a new data length. You. In this case, the obtained data length α + β (= mL− (mL−α−β))
Is set as the new data length, and the flow returns to step 301.

In step 301, the same judgment as described above is performed on the data length α + β. In this case, α, β
Is set according to the relationship α, β << L, the determination result is “YES”, and the routine proceeds to step 306. Steps
In 306, a process is performed to set the control signal requesting the master station to set the frame length to L so as to be transmitted in the frame header portion of the next frame following the currently transmitted frame. Then, the process ends.

In steps 307 and 308 shown in FIG. 2, almost the same processing as in step 306 is executed.
Processing for requesting a frame length of 2L and (m-1) L is performed, respectively.

That is, by the processing as shown in FIG. 2 described above, each slave station requests the master station for the shortest frame length among the frames whose data burst length is larger than the data length to be transmitted. . If the generated data length is longer than the longest data burst, a data burst request is made to the master station so that the data can be divided into a plurality of frames and transmitted.

The data length described in the procedure shown in FIG. 2 is, for example, in mobile communication of the TDD system,
It is defined as the length of a signal obtained by adding both a so-called data signal obtained by dividing a communication message or the like into a packet and control information such as a packet header.

Next, an algorithm in which the master station determines the next frame length in response to a data burst request from the slave station is shown in FIG.
This will be described with reference to the flowchart shown in FIG. It is assumed that the process starting from step 401 has now been started in the master station. In step 401, it is determined whether or not there has been a data burst request from any of the slave stations. That is, the frame header of the current frame (201- in FIG. 1)
1, 202-1 and 203-1), monitor whether there is a data burst request from each slave station,
If there is a data burst request from one or more slave stations, the determination result is “YES” and the process proceeds to step 402. On the other hand, if there is no data burst request from any of the slave stations, the determination result is “NO” and the process proceeds to step 404.
Here, if it is assumed that there is a data burst request including the information of the requested frame length “10L” from the slave station B, the determination result is “YES” and the process proceeds to step 402.

In step 402, when there is a data burst request from a plurality of slave stations, a slave station to which the next and subsequent frames are assigned is selected. The priority order of the slave stations serving as selection criteria is determined by, for example, a well-known method such as a round robin method. In this case, since only the data burst request from slave station B has been accepted, slave station B
Is selected, and then the process proceeds to step 403.

In step 403, the frame tailor (201-3, 202-3, and 203- of FIG. 1) of the frame currently being transmitted by the master station.
3), the frame length of the next frame is "10L"
And sends a control signal designating that the slave station B has been selected. Then, the process ends.

On the other hand, in the process of step 401,
If there is no data burst request from any of the slave stations, the determination result is "NO", and the routine proceeds to step 404.
In step 404, the shortest frame length L is designated as the next frame length by the master station, and the process ends.

Next, with reference to the flow chart shown in FIG. 4, a method of maintaining the synchronization of frames in accordance with the designation of the frame length by the master station will be described. Now, suppose that the processing procedure starting from step 501 shown in FIG. In this case, it is assumed that the longest frame length mL is 15 L, and the next step
It is assumed that the process of 501 is started at a time that coincides with the start position of the frame tailor (see 201-3, 202-3, and 203-3 in FIG. 1) of the frame currently being transmitted.

In step 501, a process of receiving a frame length designation from a control signal within the range of the frame tailor sent from the master station is performed. In this case, this reception processing is performed using a synchronization circuit designed on the assumption that the processing start time of step 501 matches the start position of the frame tailor. Next, it is determined whether or not the frame length designation from the master station has been normally received. When the frame length designation from the master station has been normally received, the determination result is “YES”, and the counter 1 for counting the number of times of waiting is set to “−2”.
On the other hand, if reception was not successful, the determination result is “NO”.
Here, the judgment result of the previous step 501 is “YE
When "S", the counter 1 is set to "-2",
Next, the process proceeds to step 502.

Now, if it is assumed that the slave station C can normally receive the frame length designation "10L", the determination result is "YES", and after the counter 1 is set to "-2", Proceed to 506. It should be noted that the processing of all the steps including the step 501 and excluding the processing of a step 507 to be described later can be considered to be negligible for the frame configuration, that is, there is no change in the position in the frame before and after the processing is executed. In a sufficiently short time.

In step 506, the frame length of the next frame is set to the designated length "10L" from the master station. In step 506, the time t at which the execution of the processing of step 506 is started is the start time (the position in the frame) of the frame header of the next frame (201-1, 202-1 and 203-1 in FIG. 1).
With reference to (t = 0), t = −β is set, and the following processing is executed. Next, step 503
Proceed to.

At step 503, it is determined whether or not the time t coincides with the start position of the frame tailor of the next frame. If they match, the determination result is “YES”, and the process returns to step 501. On the other hand, if they do not match, the determination result is "NO", and the flow proceeds to step 507. In this case, the start position 10L-β of the frame tailor of the next frame is at time t (t
= -Β), the determination result is “NO”, and the flow proceeds to step 507.

In step 507, after waiting for the shortest frame length L time, the counter 1 is incremented by one. In this case, the time t after the elapse of the L time becomes −β + L, the count value of the counter 1 is increased by 1 to “−1”, and the process proceeds to step 504. In step 504, it is determined whether the count value of the counter 1 is equal to m-1. If the count value of the counter 1 is m-1, that is, 15-1 = 14, the determination result is "YES", and the routine proceeds to step 505. On the other hand, if the count value of the counter 1 is not 14, the determination result is “NO”, and the process returns to step 503. In this case, since the count value of the counter 1 is “−1”, the determination result is “NO”, and the process returns to step 503.

Next, at step 503, it is determined whether or not the time t coincides with the start position of the frame tailor as described above. In this case, since the time t is L-β, the determination result is “NO”, and the process proceeds to step 507. Step 5
In 07, after the standby for L time of the shortest frame length is performed as described above (the time t after the standby in this case is t = 2L−
β), the counter 1 is incremented by 1 and the count value is set to “0”. Next, the process proceeds to step 504. In step 504, it is determined whether the count value of the counter 1 is equal to 14 as described above. In this case, since the determination result is “NO”, the process returns to step 503.

Thereafter, as in the case described above, step 50 is executed.
3. The processing of step 507 and step 504 is repeatedly executed with L time as one cycle. Here, assuming that the above-described processing is repeatedly executed ten times in total, in step 504, the time is t = 10L-β, and the count value of the counter 1 is “8”. Here, returning to step 503, assuming that the process of step 503 has been performed, the time t = 1
Since 0L-β matches the start position 10L-β of the frame tailor, the determination result is “YES”, and the process returns to step 501.

In step 501, a process of receiving the frame length designation from the control signal in the frame tailor transmitted from the master station is performed in the same manner as described above. In this case, the time t is the start position 10L of the actual frame tailor.
Since it is equal to -β, it is possible to secure frame synchronization and receive the frame length designation normally. Thereafter, assuming that the frame synchronization is stably performed, as in the case described above, step 501 → step 506 →
(Step 503 → Step 507 → Step 504 → Step 5
03 →…) to the next frame length to the shortest frame length L
Repeat the number of times divided by → → step 501 → step 506
→ The process of ... is repeatedly executed.

On the other hand, it is assumed that in step 501, the slave station C cannot normally receive the frame length designation "10L" from the master station. However, in this case, it is assumed that the slave station C has normally received the predetermined frame length designation from the master station in the processing of the previous step 501. In this case, in step 501, the determination result is “NO”, the counter 1 is set to “−2”, and the process proceeds to step 502.

In step 502, the frame length of the next frame is set as the shortest frame length "L". Next, after the time t, which is a reference for the subsequent processing, is initialized as t = −β, the process proceeds to step 503.

In step 503, the time t is set to the start position of the frame tailor (in this case, L
-Β) is determined. In this case, since the time t (t = −β) does not match L−β,
The judgment result is “NO”. Next, the process proceeds to step 507.

At step 507, the standby for the shortest frame length L time is performed, and the time t after the standby becomes L-β,
Next, after the count value of the counter 1 is increased by 1 to “−1”, the process proceeds to step 504. In step 504, since the count value “−1” of the counter 1 is not equal to “14”, the determination result is “NO”, and the process returns to step 503. Step 503
Then, the time t = L-β is the start position L of the frame tailor.
−β, the determination result is “YES”, and the routine proceeds to step 501.

Next, in step 501, after the processing for receiving the frame length designation transmitted from the master station is performed in the same manner as described above, the frame length designation from the master station can be normally received. Is determined. in this case,
Since the actual start position of the frame tailor is located 9 L hours after the current time t, the determination result is “NO”. Next, the routine proceeds to step 502.

Thereafter, in the same manner as described above, after the initialization of the time t (t = -β) is performed again in step 502, step 503 → step 507 → step 504 → step 503 → step 501 → step The process of 502 is repeatedly executed. Assuming that the process proceeds to step 501 after the above process is further repeated nine times, in the process of step 501, the frame length is specified from the control signal within the frame tailoring range transmitted from the master station as described above. The receiving process is performed. In this case, the counter 1
Is "8". In this case, step 50
The processing start time 1 is the actual frame tailor start time 1
0L-β, frame synchronization is ensured,
The frame length designation can be received normally.

Thereafter, assuming that the frame synchronization has been stably maintained, as in the case described above, step 501 is executed.
→ Step 506 → (Step 503 → Step 507 → Step 504): The frame length of the next frame is set to the shortest frame length L
Repeat the number of times divided by → → step 501 → step 506
→ The process of ... is repeatedly executed.

On the other hand, the aforementioned step 503 → step 507
→ Step 504 → Step 503 → Step 501 → Step 5
Step after the process of 02 has been repeated 9 more times
Assume that at the processing start time of 501, some trouble or the like occurs on the transmission line, and the frame length designation cannot be received from the control signal in the frame tailor (in this case, the start position of the frame tailor is 10L-β). , The determination result of step 501 is “NO”. In this case, since the determination result of the previous step 501 was “NO”, the counter 1
Is kept at "8", and then the step 50 is executed.
Proceed to 2.

Here, if the actual frame length of the next frame is "14L", then "14L"
Until the time has elapsed, the designation of the next frame length in step 501 cannot be received. In this case, after that, in the same manner as described above, in step 502, the next frame length is set to “L” and time t is initialized, and then step 503 → step 507 → step 504 → step 503 → Step 501 → Step 502 → Step 503 →... Are repeatedly executed. Here, the repetition processing is 6
If it has been executed a number of times, the count value of the counter 1 is incremented by one in the process of step 507 during that time, so the count value becomes “14”. At this time, if the process of step 504 is performed, the count value “14” of the counter 1 becomes
Since the value of m-1 matches the value "14", the judgment result is "YES".
And proceed to step 505.

In step 505, it is determined whether or not the frame is within the rear frame protection range. If it is within the frame rearward protection range, the determination result is “YES”, the counter 1 is decremented by 1, and the process returns to step 503. On the other hand, if it is not the frame rear range, the determination result is “NO”, and the process proceeds to step 508. Now, if it is not within the frame rear range, the determination result is “NO” and step 508 is executed.
Proceed to.

In step 508, an initial synchronization pull-in process similar to that performed in the conventional TDMA system is performed.

On the other hand, in the case described above, if it is the rear protection range of the frame, the result of the determination in step 505 is “YE
S ”, the count value of counter 1 is decreased by 1, and
After "3", the process returns to step 503. Thereafter, as described above, a series of processes of step 503 → step 501 → step 502 → step 503 → step 507 → step 504 → step 505 → step 503 →... Is repeatedly executed. Now, assuming that these processes are repeatedly executed a total of 14 times, in step 501, the start position of the frame tailor of the actual frame having the frame length of 14 and the step
Since the processing start time of 501 coincides, it becomes possible to perform processing for establishing frame synchronization and receiving designation of the frame length.

That is, according to the processing according to the flowchart shown in FIG. 5, when the frame length designation from the master station cannot be normally received on the transmission path with a code error, the processing until the next frame break is detected. , The synchronization acquisition process is repeated for each shortest frame length. Further, if the synchronization acquisition process is repeated by the number of times obtained by dividing the longest frame length by the shortest frame length, it is determined that the frame has circulated once, so that a process for determining whether or not the frame is within the rear protection range is executed.

According to the above-described embodiment, since a plurality of frames having a length of an integral multiple of the shortest frame are used as a reference, the frames of all frame lengths are basically used based on the synchronization processing of the shortest frame. Synchronous processing can be performed. Therefore, by adding a simple counter and a logic circuit to the synchronization circuit of the shortest frame, it is possible to construct a synchronization circuit that can handle all frame lengths.

According to the above embodiment, a request for a frame length is made from the slave station to the master station within the range of the frame header (see 201-1, 202-1 and 203-1 in FIG. 1). Since the master station specifies the frame length from the master station to the slave station within the range of the frame tailor (see 201-3, 202-3 and 203-3 in FIG. 1), the slave station normally sets the next frame length from the master station. If reception is successful, the slave station knows that the next frame length will be specified after the specified frame length, so it is possible to easily maintain frame synchronization even when the frame length is variable. Become. On the other hand, if the next frame length specification is not received normally, the frame length specification in the next frame comes after an integer multiple of the shortest frame length, so resynchronization is possible by repeating the synchronization acquisition process for each shortest frame length Becomes

As described above, according to the present embodiment, it is possible to adapt a plurality of frame lengths while maintaining frame synchronization with a simple hardware configuration as compared with the prior art.

[0053]

As described above, claim 1 or claim 3
According to the invention described in claim 2 , since a frame having a sub-optimal frame length can be selected according to a change in the amount of information without using a complicated frame synchronization circuit, the frame utilization efficiency is improved. The effect that it can be obtained is obtained.

Further, according to the first aspect of the invention, the first
Is requested from the slave station to the master station in the range (frame header), and the frame length is designated from the master station to the slave station in the third range (frame tailor). Since the position at which the next frame length is designated can be easily detected, the effect that the frame synchronization can be reliably maintained even when the frame length is changed is obtained.

Further, according to the second aspect of the present invention, by executing a frame synchronization processing of all the frame length based on the synchronization of the shortest length frame, the shortest synchronization circuit capable of handling all the frame length There is an effect that the configuration can be achieved by adding a simple counter and a logic circuit to the long frame synchronous circuit.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a frame configuration according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an algorithm for determining a frame length requested by a slave station.

FIG. 3 is a flowchart illustrating an algorithm for determining a frame length designated by a master station.

FIG. 4 is a flowchart illustrating a method in which a slave station maintains frame synchronization in accordance with a frame length designation from a master station.

5A and 5B are configuration diagrams illustrating a frame configuration according to a conventional TDMA system, in which FIG. 5A illustrates an example of a fixed-length frame, and FIG. 5B illustrates an example of a variable-length frame.

[Explanation of symbols]

 201-1: Frame header of shortest frame 201-2: Data burst of shortest frame 201-3: Frame tailor of shortest frame 202-1: Frame header of double-length frame 202-2: Frame header of double-length frame Data burst 202-3 ... Frame tailor of double-length frame 203-1 ... Frame header of m-length frame 203-2 ... Data burst of m-length frame 203-3 ... Frame tailor of m-length frame

────────────────────────────────────────────────── ─── Continued on the front page (56) References JP-A-6-137667 (JP, A) JP-A-2-181527 (JP, A) JP-A-2-94932 (JP, A) JP-A-2- 63229 (JP, A) JP-A-4-108226 (JP, A) JP-A-61-212931 (JP, A) JP-A-61-62253 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04J 3/00-3/26 H04L 12/40-12/44

Claims (2)

(57) [Claims] 1. A time division multiple access method for transmitting information between a master station and one or more slave stations by using a frame based on time division, wherein the frame includes first, second, and third frames. In three ranges
Therefore it is configured, in said first range, said slave station, the amount of information the one or more slave station is originated from a plurality of frame length is an integer multiple of the frame length of the shortest being predetermined Required for transmission
Main time length or more frame length and one selection, the parent
Station in the third range, wherein the master station is in the first range
Division multiple access when said at least one designated to be the frame length before Symbol frame the frame length requested by the slave station, and performing for each transmission of the frame to the one or more slave stations in Connection method. 2. Time information is transmitted between a master station and one or more slave stations.
Time-division multiple access transmitting using frames by division
In the method, the slave station is determined in advance according to an information amount of the information.
Frames that are integer multiples of the shortest frame length
Select one frame length from the lengths, and the master station
The selected frame length is defined as the frame length of the frame.
Designation of the frame to the one or more slave stations.
The transmission is performed for each transmission, and the one or more slave stations transmit the predetermined shortest
Based on the frame length, division multiple access method when you and performing frame synchronization processing.