JPH088874A - Time division multiple access method - Google Patents

Abstract

PURPOSE:To easily improve frame utilization efficiency by defining a shortest frame length as a reference, using the frame of the length which is the integral multiple ratio of the shortest frame length and performing time division multiple access. CONSTITUTION:The frame length is requested from a slave station to a master station in the range of frame headers 201-1, 202-1 and 203-1. Also, in the range of frame tailers 201-3, 202-3 and 203-3, the frame length is specified from the master station to the slave station. Then, when the slave station normally receives the next frame length from the master station, since the slave station recognizes that the next frame length is to be specified after the specified frame length, frame synchronization is easily maintained even when the frame length is varied. On the other hand, when next frame length specification is not normally received, since the frame length specification in the next frame comes after the integral multiple of the shortest frame length, resynchronization is made possible for each shortest frame length.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, T used for high-speed data communication
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.

In the case of the TDMA system in which the frame length is fixed, in order to cope with the fluctuation of the information amount, (1) the burst signal length is fixed and the number of times of transmission per frame is increased or decreased according to the information amount, 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.
A frame was constructed.

However, in the above method (1), if the burst signal length is set to be short, a preamble is required for each burst signal, so that the ratio of the overhead portion increases and the frame utilization efficiency decreases. It was Further, if the burst signal length is set to be long, it is necessary to allocate one burst signal to the smallest amount of information, so that the vacant area in the burst signal increases and the actual data transmission efficiency is lowered. On the other hand, in the case of the above method (2), a plurality of burst signals of different lengths are packed in one frame, so if short burst signals are concentrated in one frame, the time range where no signal exists Caused a decrease in frame utilization efficiency.

FIG. 5B shows another conventional example,
This is a case where the TDMA frame length is continuously adapted according to the amount of information. In this case, it is possible to improve the frame utilization 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 faster frame synchronization pull-in circuit in order to detect the start of the frame, as compared with the case of a fixed length. Therefore, in this case, 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 utilization efficiency and simplify the frame synchronization circuit at the same time. . The present invention has been made under such a background, and an object thereof is to provide a time division multiple access method capable of improving frame utilization 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 a frame by time division,
The master station selects one frame length from a plurality of frame lengths that are integer multiples of a predetermined shortest frame length according to the information amount of the information, and selects the selected frame length. Is specified as the frame length of the frame,
The time division multiple access method is characterized in that it is performed every time the frame is transmitted to the slave station.

Further, in the invention according to claim 2, the frame is constituted by three or more ranges of first, second, and third, and in the first range, the one or more slave stations. Request a frame length longer than a time length required for transmission of the amount of information generated by the master station, and in the third range, the master station uses the one or more slaves in the first range. In response to the frame length requested by the station, one frame length is selected from a plurality of frame lengths that are integer multiples of the predetermined shortest frame length,
2. The time division multiple access method according to claim 1, wherein designation of the selected frame length as a frame length of the frame is made to the one or more slave stations.

The invention according to claim 3 is characterized in that the one or more slave stations perform frame synchronization processing based on the predetermined shortest frame length. It is a time division multiple access method.

[0010]

According to the above structure, since the time division multiple access is performed using the frame having the length of the integral multiple ratio with the shortest frame length as a reference, without increasing the complexity of the frame synchronization circuit, It is possible to select a sub-optimal frame length according to the change in the amount of information, and it is possible to easily improve the frame utilization efficiency.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a frame configuration example 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 the data burst in the frame header, and the master station instructs the slave station to allocate the data burst in the frame tailor. L represents the shortest frame length (time length). In addition, each frame header 201-1, 2
The lengths of 02-1 and 203-1 are set to be constant and equal, and the lengths of the frame tailors 201-3, 202-3, and 203-3 are also set to be constant and equal.

In this case, the shortest frame having the frame length L is composed of a frame header 201-1, a data burst 201-2 and a frame tailor 201-3, and a frame header 202-1, a data burst 202-2 and a data burst 202-2. 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). ) Is shown.

In this case, the shortest frame length L is, for example, in the case of transmitting data by packetizing it in mobile communication of TDD system, etc., the minimum length of the packet is a signal such as packet control information. It is set equal to the length of time plus the length.

Next, with reference to FIG. 2, an algorithm for determining the frame length requested by the slave station to the master station when data to be transmitted to the slave station occurs will be described. It is assumed that the process starting from step 300 shown in FIG. 2 is started at a certain slave station (referred to as slave station A). In step 300, the data to be transmitted to the master station is transmitted to the slave station A (here, the data length is assumed to be mL; this data length m
L represents the longest frame length in this embodiment, and is a value of 4 or more. ) Occurs, the step
Proceeding to 301, it is judged 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 less than or equal to L-α-β, the determination result is "YES" and the process proceeds to step 306, otherwise,
The determination result is “NO”, and the process proceeds to step 302. Here, since the data length mL is 4 L or more, the judgment result is "NO".
Then, the process proceeds to step 302.

In step 302, it is judged whether the generated data length can be transmitted with a frame length of 2L. When the data length is 2L-α-β or less, the determination result is “YES” and the process proceeds to step 307. On the other hand, in other cases, the determination result is “NO”, and the same processing is repeatedly executed until step 303. in this case,
Since the data length mL is 4 L or more, the judgment result is “NO”. Then, the same processing is repeatedly executed thereafter, and the process proceeds to step 303.

In step 303, it is judged whether the generated data length can be transmitted in the frame length (m-1) L. When the data length is (m-1) L-α-β or less, 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 it is longer than L-α-β, the determination result is “NO” and the process proceeds to step 309.

In step 309, a control signal for requesting the master station to set the frame length to mL is sent to the frame header of the frame next to the frame currently being transmitted (201-1, 21-1 in FIG. 1).
(See 02-1 and 203-1) processing for transmission is performed. Then, it proceeds to step 304.

In step 304, it is judged whether the generated data length can be transmitted in the longest frame length mL. If the data length is less than mL-α-β, the judgment result is “YES”.
Then, 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 determination result is “NO”, and the process proceeds to step 305.

In step 305, the data length of the data that cannot be transmitted with the request frame length mL determined this time is calculated according to the data length- (mL-α-β) equation and set as a new data length. It In this case, the calculated data length α + β (= mL- (mL-α-β))
Is set as a new data length, and the process returns to step 301.

In step 301, the same judgment as described above is made for 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. Step
At 306, a process of setting a control signal for requesting the master station to set the frame length to L so that the control signal is transmitted in the frame header portion of the frame next to the frame currently being transmitted is performed. Then, the process ends.

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

That is, by the above-described processing shown in FIG. 2, each slave station requests the master station for the shortest frame length of the frames whose data burst length is larger than the transmitted data length. . If the generated data length is larger 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 TDD mobile communication.
It is defined as the length of a signal including both a so-called data signal obtained by dividing a communication text or the like into a packet and control information such as a packet header.

Next, FIG. 3 shows an algorithm in which the master station determines the next frame length in response to a data burst request from the slave station.
This will be described with reference to the flowchart shown in FIG. It is assumed that the master station has now started the processing starting from step 401. In step 401, it is judged whether or not there is a data burst request from any of the slave stations. That is, the frame header of the current frame (201-
1, 202-1 and 203-1) part, monitor whether there is a data burst request from each slave station,
When 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, when 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 the slave station B makes a data burst request including information of the requested frame length "10L", the determination result is "YES", and the process proceeds to step 402.

In step 402, when there are data burst requests from a plurality of slave stations, a slave station to which the next and subsequent frames will be assigned is selected. The priority order of the slave stations as the selection criterion is determined by a known method such as the round robin method. In this case, since only the data burst request from the slave station B is accepted, the 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- in FIG. 1) of the frame currently being transmitted by the master station.
(See 3), the frame length of the next frame is "10L"
And that the slave station B has been selected. The process then ends.

On the other hand, in the processing of step 401,
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.
In step 404, the master station specifies the shortest frame length L as the next frame length, and the process ends.

Next, with reference to the flow chart shown in FIG. 4, a method will be described in which each slave station maintains frame synchronization in accordance with the frame length designation from the master station. Now, it is assumed that the processing procedure starting from step 501 shown in FIG. Also, in this case, assume that the longest frame length mL was 15 L, and
It is assumed that the processing of 501 is started at a time corresponding to the start position of the frame tailer (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 transmitted from the master station is performed. In this case, this reception process is performed using a synchronization circuit designed on the assumption that the process start time of step 501 coincides with the start position of the frame tailor. Next, it is determined whether or not the frame length designation from the master station has been successfully received. When the frame length designation from the master station is normally received, the determination result is "YES", the counter 1 for counting the number of waiting times is set to "-2", and then the process proceeds to step 506.
On the other hand, if the reception was not successful, the judgment result is "NO".
Here, the judgment result of the previous step 501 is "YE
When it is "S", the counter 1 is set to "-2",
Then, it proceeds to step 502.

Now, assuming that the slave station C can normally receive the frame length designation "10L", the determination result becomes "YES" and the counter 1 is set to "-2", and then the step Proceed to 506. It should be noted that the processing of all steps including step 501, except for the processing of step 507, which will be described later, is considered to be negligible with respect to the frame configuration, that is, there is no change in position within the frame before and after processing execution. It should be done 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. Further, in step 506, the time t when the execution of the process of step 506 is started is the start time (position within the frame) of the frame header of the next frame (201-1, 202-1 and 203-1 in FIG. 1).
With reference to (reference) (t = 0), it is set that t = −β, and the following processing is executed. Then step 503
Go to.

In step 503, it is determined whether the time t matches the start position of the frame tailer 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 process proceeds to step 507. In this case, the start position 10L-β of the frame tailor of the next frame is time t (t
= -Β), the judgment result is "NO", and the routine proceeds to step 507.

In step 507, after waiting for the shortest frame length L time, the counter 1 is incremented by 1. In this case, the time t after the lapse of L time is -β + L, the count value of the counter 1 is incremented by 1 to "-1", and then 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. When the count value of the counter 1 is m-1, that is, 15-1 = 14, the determination result is "YES", and the process proceeds to step 505. On the other hand, when 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 judged 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 judgment result is “NO”, and the routine proceeds to step 507. Step 5
In 07, after waiting for L time of the shortest frame length as described above (time t after waiting in this case is t = 2L−
β), the counter 1 is incremented by 1 and the count value is set to “0”. Then, it proceeds to step 504. At step 504, it is determined whether the count value of the counter 1 is equal to 14 as described above. In this case, the determination result is “NO”, and the process returns to step 503.

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

In step 501, similarly to the case described above, a process of receiving the frame length designation from the control signal in the frame tailor transmitted from the master station is performed. In this case, the time t is the actual starting position of the frame tailor 10L.
Since it matches −β, frame synchronization can be secured and the frame length designation can be received normally. After that, assuming that the frame synchronization is stably maintained, in the same manner as in the case described above, step 501 → step 506 →
(Step 503 → Step 507 → Step 504 → Step 5
03 →…) Set the frame length of the next frame to the shortest frame length L
Repeated number of times divided by → Step 501 → Step 506
→ ... The process is repeatedly executed.

On the other hand, in step 501, it is assumed that the slave station C cannot normally receive the frame length designation "10L" from the master station. However, in this case, in the previous processing of step 501, it is assumed that the slave station C has normally received the predetermined frame length designation from the master station. In this case, in step 501, the determination result is "NO", the counter 1 is set to "-2", and then 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 the reference for the subsequent processing, is initialized as t = -β, the process proceeds to step 503.

In step 503, the time t is the start position of the frame tailer (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". Then, it proceeds to step 507.

In step 507, the shortest frame length of L time is waited, and the time t after the wait becomes L-β,
Next, after the count value of the counter 1 is incremented 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 tailer.
Since it matches −β, the determination result is “YES”, and the routine proceeds to step 501.

Next, in step 501, similarly to the case described above, after the processing of receiving the frame length designation transmitted from the master station is performed, the frame length designation from the master station can be normally received. It is determined whether or not in this case,
Since the actual start position of the frame tailer is located 9L hours after the current time t, the judgment result is "NO". Then, it proceeds to step 502.

Thereafter, in the same manner as described above, after the initialization of 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. If the process proceeds to step 501 after the above process is repeated nine more times, in the process of step 501, the frame length designation is performed from the control signal within the frame tailer range transmitted from the master station as described above. The process of receiving is performed. In this case, the counter 1
Has a count value of "8". In this case, step 50
The processing start time of 1 is the actual start time of the frame tailor 1
Since it matches 0L-β, frame synchronization is secured,
The frame length designation can be received normally.

After that, assuming that the frame synchronization is maintained stably, in the same way as the above-mentioned case, step 501
→ Step 506 → (Step 503 → Step 507 → Step 504) Set the frame length of the next frame to the shortest frame length L
Repeated number of times divided by → Step 501 → Step 506
→ ... The process is repeatedly executed.

On the other hand, the above step 503 → step 507
→ Step 504 → Step 503 → Step 501 → Step 5
Step after the processing of 02 is repeated 9 times
At the processing start time of 501, it is assumed that some trouble or the like occurs on the transmission path and the frame length designation cannot be received from the control signal within the frame tailer (in this case, the start position of the frame tailor is 10L-β). , The determination result of step 501 is “NO”, and in this case, the determination result of the previous step 501 was “NO”, so the counter 1
The count value of is held at "8" and then step 50
Go to 2.

Here, if the frame length of the actual next frame is "14L", "14L" from this time.
The designation of the next frame length in step 501 cannot be received until after a certain time. In this case, after that, in the same manner as described above, in step 502, the next frame length is set to “L” and the time t is initialized, and then step 503 → step 507 → step 504 → step The process of 503 → step 501 → step 502 → step 503 → ... Is repeatedly executed. Here, the iteration process is 6
If it is executed once, the count value of the counter 1 is incremented by 1 in the process of step 507, and the count value becomes "14". At this time, if the process of step 504 is performed, the count value "14" of the counter 1 is
Since it matches the value "14" of m-1, the judgment result is "YES".
Then, the process proceeds to step 505.

At step 505, it is judged whether or not it is within the frame rear protection range. If it is within the frame rear 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 within 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
Go to.

At step 508, an initial synchronization pull-in process similar to that performed by the conventional TDMA method is performed.

On the other hand, in the above-mentioned case, if it is the rear protection range of the frame, the judgment result of step 505 is "YE
S ”, and the count value of counter 1 is decremented by 1 and“ 1
After "3", the process returns to step 503. Thereafter, similar to the 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 tailer of the actual frame of frame length 14 and the step
Since the processing start time of 501 matches, it is possible to establish the frame synchronization and perform the processing of receiving the designation of the frame length.

That is, according to the processing according to the flow chart shown in FIG. 5, when the frame length designation from the master station cannot be normally received on the transmission line with the code error, the next frame delimiter 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 one frame has circulated, so that the process of determining whether the frame is in the backward protection range is executed.

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

Further, according to the above embodiment, the frame length request is made from the child station to the parent station within the range of the frame header (see 201-1, 202-1 and 203-1 in FIG. 1), and In the range of the frame tailor (see 201-3, 202-3, and 203-3 in Fig. 1), the frame length is specified from the master station to the slave station, so that the slave station normally determines the next frame length from the master station. If it can be received, the slave station knows that the next frame length is 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 designation cannot be received normally, the frame length designation 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 conventional technique.

[0053]

As described above, according to the invention described in claim 1, a frame having a sub-optimal frame length is selected according to a change in the amount of information without using a complicated frame synchronization circuit. Therefore, it is possible to improve the frame utilization efficiency.

According to the invention of claim 2, the first
In the range (frame header), the slave station requests the master station for the frame length, and in the third range (frame tailor), the master station specifies the frame length in the slave station. Since the position at which the next frame length is designated can be easily detected, it is possible to reliably maintain the frame synchronization even when the frame length is variable.

According to the third aspect of the invention, by executing the frame synchronization processing of all frame lengths on the basis of the synchronization processing of the shortest length frame, the synchronization circuit that can handle all frame lengths is shortest. An effect is obtained in that it can be constructed by adding a simple counter and a logic circuit to the long frame synchronization circuit.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing an algorithm for determining a frame length required by a mobile station.

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

FIG. 4 is a flowchart showing a method in which a slave station maintains frame synchronization according to a frame length designation from a master station.

5A and 5B are configuration diagrams showing a frame configuration according to a conventional TDMA method, in which FIG. 5A is an example of a fixed length frame and FIG. 5B is an example of a variable length frame.

[Description of Codes] 201-1 ... Frame header of shortest length frame 201-2 ... Data burst of shortest length frame 201-3 ... Frame tailor 202-1 of shortest length frame ... Frame header 202-2 of double length frame ... Double-length frame data burst 202-3 ... Double-length frame frame tailor 203-1 ... m-double frame frame header 203-2 ... m-double frame data burst 203-3 ... m-double frame frame Teira

Claims (3)

[Claims] 1. A time division multiple access method for transmitting information between a master station and one or more slave stations using a frame by time division, wherein the master station, in accordance with the information amount of the information, Designating one frame length from a plurality of frame lengths that are integer multiples of a predetermined shortest frame length and designating the selected frame length as the frame length of the frame,
A time division multiple access method, characterized in that it is performed for each of the one or more slave stations every time the frame is transmitted. 2. The frame includes a first frame, a second frame, and a third frame.
In the first range, the master station is requested to have a frame length that is equal to or longer than a time length necessary for transmission of the amount of information generated by the one or more slave stations in the first range. In the third range, the master station is an integer multiple of the predetermined shortest frame length according to the frame length requested by the one or more slave stations in the first range. 7. A frame length is selected from a plurality of frame lengths, and designation of the selected frame length as a frame length of the frame is performed for the one or more slave stations. 1. The time division multiple access method described in 1. 3. The time division multiple access method according to claim 1, wherein the one or more slave stations perform frame synchronization processing based on the predetermined shortest frame length.