JPH11355254A - Communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to attain optimization of a transmission system and, at the same time, to enable efficient use of a memory space. SOLUTION: In a data link protocol in an SR-ARQ retransmission control system, a function to measure a transmission-rate or transmission quality of data is provided. The measured transmission quality or the transmission rate is made to change an error correction system as a transmission system of a transmission line 10. Also, a size of a frame buffer for data retransmission of the SR-ARQ is made variable by the measured transformation quality and an empty buffer part is allocated to the memory space for other processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various communication media such as a mobile communication network (cellular phone, PHS, MMAC, etc.), a wired telephone network, an ISDN network, a satellite communication network, a satellite broadcasting network, and an Internet network. The present invention relates to a communication apparatus having a function of transmitting and receiving information data or audio / video regardless of location using a communication form.

[0002]

2. Description of the Related Art In a conventional communication apparatus, the reception power (or electric field strength = RS
SI), CRC check, FEC (Forward E
The communication quality has been determined from the number of error corrections of the error correction (error correction).

[0003] The determination of the communication quality based on the received power is a method of measuring the signal strength of a signal received at a physical layer interface section of a communication transmission line, and determining the quality of the communication line based on the measured value of the signal strength. .

[0004] The judgment of the communication quality by the CRC check is as follows.
This is performed as follows. That is, on the data transmission side,
CRC (Cycle) for transmission data in frame units
A cRedundancy Check) operation is performed, and the resulting CRC code is added to transmission data for error detection and transmitted. On the receiving side, a similar CRC calculation is performed on the received data in frame units, and the calculation result is compared with the received additional data, that is, the CRC code. If they match, there is no error in the data of the frame. If they do not match, it is determined that there is an error in the data. The quality of the transmission path is determined by measuring the number of errors detected in a plurality of predetermined frames or in a unit time using the determination result.

The communication quality is determined by the number of FEC error corrections, for example, by adding a fixed number of bits of data corrected by error correction using a Viterbi decoding method or the like, and determining the quality based on the number of corrected data. It is to do.

Conventionally, the quality of a transmission path is determined by the above-described transmission quality determination method, and the state of the transmission path is appropriately changed.

[0007] In a conventional communication device using, for example, SR-ARQ in a link layer error correction section which is higher than the physical layer, there is a communication device having a function of measuring an error rate in a frame unit.

[0008]

As described above, in the conventional transmission quality judging method, not the actual transmission amount of data (contents) but the strength of radio waves and the error detection in the physical layer in the transmission path. Secondary method based on the result, etc., or transmission quality in the physical layer of the transmission line (transmission efficiency as a device of the transmission line)
Was measured. In this method, the data transmission state is determined only from the transmission quality and transmission state of the wireless system.

However, originally, it is important to appropriately control the transmission path from the viewpoint of not only the radio system but also the overall transmission system including the flow control and the processing delay of the upper layer. is there.

For example, even in a state where the data flow passed from the transmission system cannot be processed due to the high load of the application processing of the upper layer, and the flow control is applied between the transmission unit and the application, the same method is conventionally used. Although transmission has been continued as it is, if this is switched to an efficient transmission method in the transmission system, the transmission path can be used very effectively.

A more specific example will be described below.
In the case of EC, there is a communication system in which transmission quality is higher when data is transmitted with higher redundancy than when data is transmitted while weighting by flow control is applied in a state of low redundancy or data is retransmitted. However, even in such a communication system, conventionally, an appropriate redundancy has not been selected for an overall transmission state.

In the conventional SR-ARQ, the number of modulo frames (frame buffer for data retransmission) has not been changed according to the transmission quality. In this case, a method of preparing a redundant buffer has been adopted.

For this reason, especially when the capacity of the memory is limited, such as in a portable terminal, the memory area cannot be changed dynamically even if the transmission path is in a good state. Frequently, it was not possible to handle data of a relatively large size, or a situation in which a swap occurred to cause a reduction in execution speed.

In view of the above, it is an object of the present invention to provide a communication apparatus and a communication method that can optimize a transmission system and enable efficient use of a memory space.

[0015]

In order to solve the above-mentioned problems, a communication apparatus according to the present invention uses an SR-ARQ (Sel
active Repeat type AutomaticR
In a communication apparatus adopting a retransmission control method of an "epeate reQuest" method, a function of measuring a data transmission speed or a transmission quality in a data link protocol in the retransmission control method is provided.

According to the communication device having the above configuration, the SR-A
Since the data transmission rate or transmission quality is measured in the data link protocol of the retransmission control method of the RQ method, optimization of the transmission method and efficient operation of the buffer memory are performed using the transmission rate or the transmission quality. Can be expected.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a communication device according to the present invention will be described below with reference to the drawings. FIG. 1 shows an overall block diagram of a communication apparatus according to this embodiment. The communication apparatus according to this embodiment includes a physical layer data receiving unit 11, an error correction unit 12, a transmission rate measurement within an ARQ protocol. It comprises a unit 13, an ARQ frame synchronization sequence transmission quality measuring unit 14, an error correction control unit 15, an encoding and retransmission control transmitting unit 16, and a physical layer data transmitting unit 17.

A physical layer data receiving unit 11 and a physical layer data transmitting unit 17 are connected to the transmission line 10,
Also, for the application 18 as an upper layer,
An error correction unit 12, an error correction control unit 15, an encoding and retransmission control transmission unit 16 are connected to each other.

This communication device includes a physical layer data receiving unit 11
, Receives data through the transmission path 10, and the error correction unit 12 uses FRQ such as ARQ method or Viterbi decoding method.
Error correction is performed by EC.

One of the blocks is a transmission rate measuring unit 13 in the ARQ protocol, which measures a data transmission rate in the data link protocol in the retransmission control system of the ARQ system. In this example,
The transmission rate measuring unit 13 in the ARQ protocol has a function of measuring output data per unit time in the ARQ protocol,
It has a function of transmitting this measurement result to the error correction control unit 15.

Another block is a transmission quality measuring unit 14 in the ARQ frame synchronization sequence, which is an ARQ frame synchronization sequence.
This part measures the data quality in the frame synchronization sequence in the data link protocol in the retransmission control method of the Q method. In this example, the ARQ frame synchronization sequence transmission quality measuring unit 14 sends out an ARQ synchronization frame, and holds the state of the synchronization sequence that accepts this synchronization frame until the transmission quality is measured. Is obtained, the transmission quality information is transmitted to the error correction control unit 15.

The error correction control unit 15 determines the transmission quality and the transmission speed from the results reported from the transmission rate measurement unit 13 in the ARQ protocol and the transmission quality measurement unit 14 in the ARQ frame synchronization sequence. Therefore, a function of determining and switching an error correction method as an appropriate transmission method, in the case of ARQ, setting of a buffer area for data retransmission according to the required number of modulo frames, and an empty modulo buffer area Has the function of releasing the function to other functions.

The encoding and retransmission control transmission section 16 is a section for constructing transmission data according to the transmission method determined by the error correction control section 15, and passes the data to a physical layer data transmission section 17 at the next stage, where the data is transmitted. Send.

The above is the general outline of the communication apparatus of this embodiment. Each block will be described below in more detail.

The error correction unit 12 has both the FEC such as Viterbi decoding, Reed-Solomon code, and BCH code, and the error correction function of the ARQ retransmission control method, and the case of having only the error correction function of the ARQ retransmission control method. There are two ways. In this embodiment, the case where the error correction unit 12 has both the FEC such as the Viterbi decoding and the error correction function of the ARQ retransmission control method will be described.

FIG. 2 shows an example of the configuration of the error correction unit 12 in this embodiment.
, An FEC error correction unit 123, a system switching unit 121 for switching which one of the ARQ error correction unit 122 and the FEC error correction unit 123 is adopted, and a memory unit 124 forming a modulo buffer.
And a memory interface 125.

The memory interface 125 performs not only the interface processing between the memory 124 and the application 18 but also the interface processing between the application 18 and the ARQ error correction unit 122 and the FEC error correction unit 123.

The system switching unit 121 operates the error correction unit according to the error correction system determined by the error correction control unit 15 in response to the error correction system instruction from the error correction control unit 15.

Further, when the determined error correction method is the ARQ error correction method, the method switching unit 121
The ARQ error correction unit 122 sends the ARQ modulo number instruction information from the error correction control unit 15. Then, the ARQ error correction unit 122 secures the area of the modulo buffer in the memory unit 124, and releases the other area for other processing.

For example, when the ARQ error correction unit 122 is operated with a modulo number of 63, it is necessary to constantly reserve a buffer area for 63 modulo in the memory 124. However, when the transmission quality is very good, there is almost no error in actual transmission, so that the operation is performed in a state in which modulo retransmission hardly occurs. In such a state, if the modulo number is set to a value assuming that the transmission quality is poor, the modulo buffer is used in a very redundant manner. In the above example, 63 modulo numbers are not actually required, and even a half modulo 30 can provide sufficiently equivalent transmission efficiency.

In the case of this embodiment, when an error correction method based on ARQ is used and an instruction to reduce the number of modulos is given from the error correction control unit 15, the memory 124 stores, for example, the data shown in FIG. Memory area A shown in
Only as a modulo buffer, and the other memory area B is released for other processing.
Has a function that makes it possible to access the memory area B.

In the error correction unit 12, the FEC such as Viterbi is used in the data communication under the condition that the transmission quality is poor and the flow of the received data is controlled due to the heavy processing of the application 18. If the error correction control unit 15 determines that the data is to be transmitted by multiplying the data, it has a function of selecting convolutional encoding / decoding (Viterbi decoding) in the lower layer of the ARQ, that is, the physical layer, and a function of selecting bit interleaving. It has a function of determining whether or not there is an FEC from the data configuration and switching the processing.

The transmission rate measuring unit 13 in the ARQ protocol
Has a function of measuring the number of data transmitted to the application 18 in this embodiment during a general ARQ protocol sequence. The transmission rate measuring unit 13 in the ARQ protocol measures the total data transfer amount, and sends the error correction control unit 15 at regular intervals.
It has a function to report the measurement result. Since this is the number of data per fixed time, this corresponds to the data transmission speed.

After entering the data communication state, the ARQ
The error correction unit 12 issues a measurement start instruction to the intra-protocol transmission rate measurement unit 13. The transmission rate measuring unit 13 in the ARQ protocol resets a counter value for counting the amount of data transmitted to the application 18 in response to the instruction to start the measurement. In the operation sequence (ARQ protocol sequence) based on the normal ARQ error correction method, the modulo data length is added at the timing of resetting the non-reception flag of modulo data that can be output. After the measurement for a certain period of time, the measurement is terminated and the error correction control unit 13 is notified of the result of adding the data amount.

FIGS. 3 and 4 show a general SR-ARQ.
Shows a reception sequence example of PIAFS, which is data communication in PHS.

First, in step S1, it is determined whether or not there is a reception flow control request, and if not, the process proceeds to step S2, where it is determined whether or not the received data is erroneous. If an error is detected, the frame is discarded in step S8, and in step S11, the backward information N (S) to be transmitted to the base station is set to the frame number V (R1).

If it is determined in step S2 that there is no error, the flow advances to step S3 to temporarily store the FBI (received request frame number from the game) for the transmission frame determination flow. Then, the process proceeds to step S4 to determine whether the data length is zero and the FFI (modulo number of the received frame) is zero, and if so, the process proceeds to step S8 to discard the frame.

In step S4, the data length is not zero,
Or FFI (modulo number of the received frame)
Is determined to be not zero, the process proceeds to step S5, and the process proceeds to step S6 assuming that the backward information N (S) = FFI to be transmitted to the base station. In step S6, it is determined whether or not the last one byte of the data area is equal to one byte of the same frame number in the reception frame buffer.

If the result of determination in step S6 is that they are equal, the flow advances to step S8 to discard the frame, and further to step S11, where the backward information N (S) is replaced with the frame number V (R1). I do. Also,
When it is determined that they are not equal, the process proceeds to step S7, where the backward information N (S) (= FF) to be transmitted to the base station is transmitted.
The unreceived flag RF (N) corresponding to the frame of I)
(S)) is set to RF (N (S)) = 1.

Then, the process proceeds to a step S9, where the received data is fetched into the received frame buffer, and then the step S1
At 0, it is determined whether or not the request frame number V (R1) = N (S). If the result of the determination is that the requested frame number V (R1) is different from the backward information, the process proceeds to step S11, where N (S) = V (R1). When the request frame number V (R1) = N (S), the process proceeds to step S12 in FIG. 4, and the unreceived flag RF (V1) corresponding to the frame of the request frame number V (R1).
(R1)) = 0. At this point, the frame of the number V (R1) can be passed to the higher order.

In the ordinary protocol, after step S12, the process proceeds to step S13, where V (R1) = V (R1) Mod. The operation of M + 1 is performed. Then, the process proceeds to step S14, and the non-receiving flag RF (V (R
It is determined whether 1)) is 0 or not. If it is 0, the process proceeds to step S11 and the backward information N (S) is set to the frame number V (R1).

The above is the sequence of the ordinary ARQ protocol. In this embodiment, the sequence shown in FIG. 3 is exactly the same, but the part shown in FIG. 4 is different, as shown in FIG. Become.

That is, after step S12, the process proceeds to step S20, where the data amount DS is calculated by the following equation: DS = DS + DL (V (R1)) (Equation 1). That is, as described above, when there is a measurement start instruction from the error correction unit 12, the data amount DS is initialized as DS = 0. Then, after a certain period of time has elapsed after the start of the measurement using the above (Equation 1),
The data amount DS of the calculation result as the measurement result is notified to the error correction control unit 15.

As described above, in this embodiment,
The error correction control unit 15 can detect the transmission rate from the data amount DS within a predetermined time of the measurement result from the transmission rate measurement unit 13 within the ARQ protocol during the reception sequence of the ARQ error correction method.

The transmission quality measuring unit 14 in the ARQ frame synchronization sequence is different from the general ARQ synchronization establishment protocol shown in FIG. 6 in the sequence of the synchronization establishment protocol shown in FIG. The data transmission quality is measured by a simple operation.

First, when a desired communication device is operated on the activation side (originating side), data quality is measured by executing the sequence shown in FIG.

That is, when a synchronization request frame is issued from the initiating side, the apparatus enters a state of waiting for synchronization reception from the other party, and usually immediately shifts to a control frame as shown in FIG. 6 when the synchronization reception from the other party is received. Then, setting of communication parameters is started. However, in this embodiment, as shown in FIG. 7, from the start of receiving the synchronization reception from the partner side until the transmission quality can be measured, the state of the synchronization reception is held, and the transmission quality is measured. To the error correction control unit 15, and after an error correction method is instructed, the sequence shifts to a sequence for transmitting a communication parameter setting request.

For example, in the example of FIG. 7, after measuring the number of error frames for 25 frames, the process is shifted to the control frame. This method has a function of detecting a frame error of 4% or more. The result of the transmission quality is reported to the error correction control unit 15.

In the sequence of FIG. 7, on the actuated side, the same operation as in the conventional sequence of ARQ shown in FIG. 6 may be performed.

Next, the operation of the error correction control unit 15 will be described.

FIG. 8 shows an example of the operation procedure of the error correction control unit 15 when the transmission quality measurement result is notified from the transmission quality measurement unit 14 in the ARQ frame synchronization sequence.

For example, based on the transmission quality reported by the ARQ frame synchronization sequence transmission quality measuring unit 14, if the data content is not real-time data and the transmission quality is less than a specified value (4% in this example). If so, it is determined that even if the modulo is reduced to half the normal speed, the effective speed does not deteriorate so much, and an instruction is given to the error correction unit 12, the encoding and retransmission control transmission unit 16 to operate the modulo number at half. put out. If the transmission quality exceeds a certain prescribed value, the number of modulos is increased to prevent the total transmission speed from deteriorating.

That is, in FIG. 8, step S31
Then, it is determined whether or not the application type handles real-time data. If it is determined that the application type is real-time data, the process proceeds to step S38, and an instruction to set an FEC method such as a convolutional code is sent to the error correction unit. 12, the encoding and retransmission control transmission unit 1
Send to 6.

That is, in the case of real-time transmission of voice or moving image, since the condition of the real-time property is more severe than the transmission quality, an error correction method such as FEC using a convolutional code or the like is selected rather than ARQ. Error correction unit 12
Is issued to the encoding and retransmission control transmission unit 16.

If it is determined in step S31 that the data is not real-time data, the process proceeds to step S32, and waits for reception of a synchronization acceptance notification, and then proceeds to step S33. In step S33, the synchronization reception is received, and measurement start of a frame error is instructed. Then, the process proceeds to step S34, where the ARQ frame synchronization sequence transmission quality measuring unit 1
4 to wait for reception of the report of the transmission quality measurement result, and upon confirming the reception, proceeds to step S35.

In step S35, it is determined whether or not the number of errors has exceeded the specified value. If not, the flow advances to step S36 to issue an instruction to set the modulo number of ARQ to a half value. It is sent to the error correction unit 12.
If it is determined in step S35 that the value exceeds the specified value, the process proceeds to step S37, and an instruction to set the ARQ modulo number to the maximum value is sent to the error correction unit 12. As described above, when the modulo number of the ARQ is set to a half value, the error correction unit 12
Only area A of area 4 is used as a modulo buffer, and area B is released for other processing.

In the above example, the specified value of the number of errors is 1
In this case, if the specified value is divided into several steps, it is possible to set a more detailed modulo number.

Next, FIG. 9 shows a case where the transmission rate measurement result is notified from the transmission rate measuring unit 13 in the ARQ protocol.
4 shows an example of an operation procedure of the error correction control unit 15.

After entering the data communication state, the error correction control unit 15 sends the ARQ protocol transmission rate measurement unit 13
Notifies the result of addition of the data amount. When this value is degraded to a value less than or equal to the reference speed calculated by the type of the transmission path and the application type is not real-time data, the error correction unit 12, the encoding and retransmission control transmission unit 16 Give synchronization instructions. Further, in the case of a communication device having the functions of convolutional code, Viterbi decoding, and bit interleaving in the configuration block shown in FIG. 1, an instruction is given to operate the communication device.

That is, in FIG. 9, step S41
Then, it is determined whether or not the type of the application handles real-time data. If it is determined that the application type is the real-time data, no processing is performed, and the process ends. If it is determined in step S41 that the data is not real-time data, the process proceeds to step S42, where it is determined whether the number of data exceeds the reference value. If not, the process ends.

If the number of data exceeds the reference value, the flow advances to step S43 to determine whether or not an FEC function such as convolution or Viterbi decoding is provided. If not, the flow advances to step S45 to send an ARQ resynchronization instruction to the error correction unit 12. If so, step S44
Sends an instruction to the error correction unit 12 to set an FEC scheme such as a convolutional code, and then proceeds to step S45 to send an ARQ resynchronization instruction to the error correction unit 12.

The coding and retransmission control transmitting section 16 performs A / A control in accordance with the error correction method specified by the error correction control section 12.
It has a function of performing RQ retransmission operation or convolutional coding for FEC and bit interleave processing, and then performs framing and data transmission in the same manner as existing communication devices.

As described above, according to the present embodiment, it becomes possible to select appropriate retransmission control parameters in accordance with a change in the state of the transmission line, and when the state of the transmission line is good, the apparatus can be selected. Since the data buffer or the memory as the internal storage device has a margin, the memory and the buffer thus formed can be used for other applications.

For example, by taking in a large image or expanding the swap area, the substantial processing speed is improved. In particular, when the storage device is restricted, such as a portable terminal, there is a remarkable effect in effectively using the memory and the buffer.

Further, in a system for transmitting data by multiplexing data of various speeds on one transmission line, the data speed can be appropriately varied, and the transmission line can be used efficiently. . In other words, if the upper layer does not have a data processing speed higher than a certain level, transmitting data at a higher data transmission speed is redundant as a system. Since the data speed can be distributed, the redundancy can be reduced as compared with the conventional method, and as a result, efficient multiplexing can be performed.

For example, in such a communication mode, the downlink is multiplexed and transmitted at a relatively high speed, such as in satellite communication, and when the uplink is a narrow system, the multiplexing is performed from the state of the uplink side. The transmitting station that can perform the control of the data multiplexing can be efficiently performed.

Further, in the case of a communication system in which redundancy can be varied by FEC using a convolutional code, the redundancy can be appropriately set by the transmission rate reported from the transmission rate measuring unit 13 in the ARQ protocol. .

Thus, in a communication mode in which an error frequently occurs in the transmission path, it is possible to increase the redundancy of the convolutional code to reduce the transmission speed, thereby increasing the real-time error correction capability in the physical layer. You can do it.

In addition, according to the above-described embodiment, by providing the function of measuring the overall transmission rate in the error correction sequence, if only the interface of the physical layer is considered with respect to a change in the form of the transmission line, Can respond. For this reason,
It is not necessary to provide various error measuring means for each transmission mode. As a result, an appropriate error correction method can be selected by one method regardless of the type of the physical layer. That is, in the device configuration of the communication device, the device configuration can be applied to various communication systems with the physical layer separated as an interface.

Further, as in the above-described embodiment, by providing a function of measuring the data transmission rate in the retransmission control (ARQ) sequence in the link layer in the data transmission terminal, It is possible to measure the data transmission speed of the system as a whole, such as the state of the transmission path, the state of the ARQ control unit, and the state of the processing part higher than the application layer.

According to the transmission state determined by this,
In the case of a system that adapts to a communication system corresponding to a variable rate or multiplexes and transmits data of various speeds such as satellite communication, the transmission speed determined by the above method can be declared to the scheduler of the multiplexing device. The transmission rate is lowered, and appropriate multiplexing is realized without securing redundant bandwidth.
Also, in the case of a system such as a convolutional code that can vary the redundancy in FEC, if a decrease in transmission quality is detected,
By controlling to increase the redundancy, effective use of the transmission path is realized.

[0072]

As described above, according to the present invention, the data transmission rate or the transmission quality is provided in the data link protocol in the ARQ retransmission control system, so that the measured transmission is provided. The transmission system can be optimized by using the speed or the transmission quality, and the buffer memory space can be efficiently used.

[Brief description of the drawings]

FIG. 1 is an overall block diagram of an embodiment of a communication device according to the present invention.

FIG. 2 is a block diagram showing a detailed example of some blocks in FIG. 1;

FIG. 3 is a diagram illustrating a protocol of an ARQ retransmission control method.

FIG. 4 is a diagram illustrating a protocol of an ARQ retransmission control method.

FIG. 5 is a diagram for explaining a protocol of an ARQ retransmission control method in which a main part of the present invention is added.

FIG. 6 is a diagram showing a general sequence of a data link of the ARQ retransmission control method.

FIG. 7 is a diagram showing a data link sequence of the ARQ retransmission control method in the embodiment of the communication device according to the present invention.

FIG. 8 is a flowchart for explaining the operation of the main part in the embodiment of the communication device according to the present invention.

FIG. 9 is a flowchart for explaining an operation of a main part in the embodiment of the communication device according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Transmission path, 11 ... Physical layer data reception part, 12 ... Error correction part, 13 ... Transmission rate measurement part in ARQ protocol, 1
4 ... ARQ frame synchronization sequence transmission quality measurement unit
15: Error correction control unit, 16: Coding and retransmission control transmission unit, 17: Physical layer data transmission unit, 18: Upper layer application

Claims (6)

[Claims] 1. An SR-ARQ (Selective Re)
Pet type Automatic Repeat reQ
A communication device adopting a retransmission control method of a west method, wherein a function of measuring a data transmission speed or a transmission quality in a data link protocol in the retransmission control method is provided. 2. The communication apparatus according to claim 1, wherein the transmission quality of the data is measured at a stage of acquiring an ARQ frame synchronization which is initially performed by the data link protocol. A communication device characterized by the above-mentioned. 3. The communication device according to claim 1, wherein the measurement of the data transmission rate is performed in the ARQ sequence. 4. The communication device according to claim 1, wherein the measured transmission quality or the transmission speed
A communication device for changing an error correction method as a transmission method of a transmission path. 5. The communication device according to claim 4, wherein an appropriate error correction method is selected according to a type of a higher-order application. 6. The communication device according to claim 2, wherein the size of a frame buffer for SR-ARQ data retransmission is made variable according to the measured transmission quality, and a free buffer portion is used as a memory for another processing. A communication device having a control function of allocating to a space.