JP2010166131A - Radio transmitter, and control method and program therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance transmission efficiency by preventing a buffer overflow and a packet loss in a radio transmitter provided with an interface for inputting and outputting a transmission speed variable data signal. <P>SOLUTION: The radio transmitter includes: and input/output port 1 which is the interface for inputting and outputting the transmission speed variable data signal; a buffer control part 2 for buffering the data signal; a buffer monitoring part 3 for outputting a modulation system change propriety signal on the basis of a buffer storage information signal and a prescribed buffer threshold inputted from the buffer control part 2; an adaptive modulation control part 8 for determining the switching and switching timing of the modulation system of the data signal on the basis of the modulation system change propriety signal and outputting modulation system control signal when switching the modulation system; and a modem 5 for switching the modulation system on the basis of the modulation system control signal and modulating the data signal by the switched modulation system. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radio transmission apparatus, a control method thereof, and a program, and more particularly, to a radio transmission apparatus having an interface for inputting / outputting a data signal having a variable transmission rate, a control method thereof, and a program thereof.

  In the technical field related to a wireless transmission device employing an adaptive modulation system, for example, Patent Documents 1 and 2 have been filed prior to the present application.

  In Patent Document 1, for example, referring to paragraphs 0005, 0016, 0027, 0028, etc., the queue length Q of the packet allocation buffer is monitored, and when Q is outside a predetermined range, the rate R is increased stepwise. There is a description about this, and the transmission band of the wireless line is changed in accordance with the requested communication amount.

JP 2003-324376 A JP 2007-258865 A

  Data such as transmission bandwidth reservation, low delay, low packet loss rate, etc. to support services that do not allow delay or stop of communication such as real-time distribution of voice and video, videophone, etc. on networks where various communication services are mixed There is a need for technology to ensure transmission quality. As for the wireless transmission apparatus constituting the network, an adaptive modulation system has been proposed in which the modulation system is changed according to the line condition of the wireless transmission path to ensure an optimal wireless transmission capacity.

  For example, Patent Document 2 discloses an ITU-T G.264 data signal and a transmission rate variable data signal corresponding to an adaptive modulation method, in which data such as LAN is generated in bursts. In a wireless transmission device in which data signals with a constant transmission rate as defined in 703 are multiplexed in a wireless transmission band, data with a constant transmission rate is used to cope with fluctuations in the wireless transmission capacity due to a modulation scheme change. There has been proposed a modulation scheme having the lowest multi-level number, that is, a scheme in which a data signal having a variable transmission rate is allocated to the remaining bandwidth, that is, less than the minimum transmission bandwidth.

  However, in the above-described method, a data signal with a constant transmission rate is considered with respect to a change in radio transmission capacity due to a modulation method change. However, a data signal with a variable transmission rate (hereinafter referred to as LAN data) is considered. Not considered. For this reason, there are the following problems.

  The first problem is that the LAN data input buffer cannot absorb the fluctuation of the wireless transmission capacity due to the change of the modulation method depending on the data accumulation amount when the modulation method is changed in the LAN data input buffer. Overflow and packet loss occur and transmission efficiency decreases.

  The second problem is that in order to prevent the first problem described above, it is necessary to mount a large memory in the LAN data input buffer, which increases the circuit scale.

  Therefore, in view of the above circumstances, the present invention aims to prevent buffer overflow and packet loss and improve transmission efficiency in a wireless transmission device having an interface for inputting and outputting a data signal having a variable transmission rate. To do.

  In order to achieve the above object, a wireless transmission device according to the present invention is a wireless transmission device compatible with an adaptive modulation method, and includes an input / output unit that is an interface for inputting and outputting a data signal having a variable transmission rate, Buffer control means for buffering the data signal input from the entry output means, and a buffer for outputting a modulation system change enable / disable signal based on the buffer storage information signal input from the buffer control means and a predetermined buffer threshold A monitoring unit and an adaptation for determining a modulation scheme switching and switching timing of the data signal based on the modulation scheme change enable / disable signal input from the buffer monitoring unit, and outputting a modulation scheme control signal when switching the modulation scheme Modulation control means, switching the modulation system based on the modulation system control signal, and switching modulation system Characterized in that it comprises a modulation and demodulation means for modulating the data signal.

  A method for controlling a radio transmission apparatus according to the present invention includes: an input unit that is an interface for inputting / outputting a data signal having a variable transmission rate; and a modulation scheme that is switched based on a modulation scheme control signal. And a modulation / demodulation means for modulating the data signal, and a control method of a wireless transmission apparatus corresponding to an adaptive modulation system, wherein the buffer control step performs a buffering process on the data signal input from the input / output means; A buffer monitoring step for outputting a modulation scheme change enable / disable signal based on the buffer accumulation information signal input by the buffer control step and a predetermined buffer threshold; and the modulation method change enable / disable signal input by the buffer monitor step. Based on the data signal modulation scheme switching and switching timing, switching the modulation scheme Characterized in that it comprises a, and adaptive modulation control step of outputting the modulation scheme control signal when that.

  The program according to the present invention performs switching of a modulation method based on an input means that is an interface for inputting and outputting a data signal having a variable transmission rate, and a modulation method control signal, and the data signal is transferred by the changed modulation method. A buffer control process for buffering the data signal input from the input / output means and a buffer input by the buffer control process to a wireless transmission apparatus that supports an adaptive modulation system. A buffer monitoring process for outputting a modulation scheme change enable / disable signal based on the stored information signal and a predetermined buffer threshold; and a modulation scheme switching of the data signal based on the modulation scheme change enable / disable signal input by the buffer monitoring process; Adaptation that determines the switching timing and outputs the modulation system control signal when switching the modulation system Characterized in that to execute the tone control process, the.

  According to the present invention, in a wireless transmission device having an interface for inputting / outputting a data signal having a variable transmission rate, it is possible to prevent buffer overflow and packet loss and improve transmission efficiency.

It is a block diagram which shows the structure of the radio | wireless transmission apparatus which concerns on embodiment by this invention. 3 is a flowchart for explaining a modulation timing switching timing of the apparatus shown in FIG. 1. It is a block diagram which shows the structure of the radio transmission apparatus which concerns on other embodiment by this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  The embodiment described below has an interface for LAN data input / output, and monitors the data accumulation amount of the LAN data input buffer in a wireless transmission apparatus compatible with the adaptive modulation method, and modulates the data accumulation amount in the buffer. By adjusting the timing for switching the method, buffer overflow and packet loss are prevented, and transmission efficiency is improved.

<First Embodiment>
The configuration of the first embodiment will be described with reference to FIG.

  First, a configuration until the transmission LAN signal s10 input from the input / output port 1 is output as the wireless transmission / reception signal s14 from the wireless processing unit 6 will be described.

  The transmission LAN signal s10 input from the input / output port 1 is input to the buffer control unit 2, and after buffering processing, is output to the radio frame processing unit 4 as a transmission MAC frame signal s11. The buffer control unit 2 outputs a buffer accumulation information signal t10 indicating the buffer accumulation amount to the buffer monitoring unit 3. Note that the buffer control unit 2 has a function of adjusting the packet flow rate of the transmission LAN signal s10 input to the input / output port 1 by Flow Control control or Back Pressure control specified by IEEE 802.3x. A PAUSE frame signal or a collision signal is output from the input / output port 1 in accordance with the PAUSE control signal t11 input from the monitoring unit 3.

  The buffer monitoring unit 3 determines whether or not the modulation method can be changed based on the buffer accumulation information signal t10 input from the buffer control unit 2 and the radio band change signal t19 input from the adaptive modulation control unit 8, and outputs a modulation method change enable / disable signal t18. Output to the adaptive modulation control unit 8.

  The transmission MAC frame signal s11 and the transmission modulation scheme change signal t12 input to the radio frame processing unit 4 are output to the modulation / demodulation unit 5 as a transmission baseband signal s12 after being multiplexed into the radio frame. The transmission baseband signal s12 input to the modulation / demodulation unit 5 is modulated and then output to the wireless processing unit 6 as a transmission modulation signal s13. Here, the modem unit 5 controls the modulation method according to the modulation method control signal t15 input from the adaptive modulation control unit 8. The radio processing unit 6 performs radio transmission processing such as DA conversion and frequency conversion on the transmission modulation signal s13 input from the modulation / demodulation unit 5, and then transmits the radio transmission / reception signal s14 from the antenna unit 7.

  The adaptive modulation control unit 8 determines the modulation method of the local station apparatus in accordance with the reception modulation method change signal t13 input from the radio frame processing unit 4 to be described later, and the modulation method change enable / disable signal t18 input from the buffer monitoring unit 3 Thus, the modulation system change timing is determined, and the modulation system control signal t15 is output to the modem unit 5 and the wireless processing unit 6. Further, the modulation scheme of the radio facing device is determined from the bit error information signal t14 input from the modem unit 5 described later and the received radio level information signal t17 input from the radio processing unit 6, and the transmission modulation scheme change signal t12 is wirelessly transmitted. Output to the frame processing unit 4.

  Next, a configuration until the wireless transmission / reception signal s14 received from the antenna unit 7 is output from the input / output port 1 as the reception LAN signal s18 will be described.

  The radio transmission / reception signal s14 received from the antenna unit 7 is output to the modulation / demodulation unit 5 as a reception demodulated signal s15 after the radio processing unit 6 performs radio reception processing such as frequency conversion and AD conversion. The received demodulated signal s15 input to the modem 5 is demodulated and then output to the radio frame processor 4 as a received baseband signal s16. The modem unit 5 controls the demodulation method according to the demodulation method control signal t16 input from the adaptive modulation control unit 8. The reception baseband signal s16 input to the radio frame processing unit 4 is output to the buffer processing unit 2 as a reception MAC frame signal s17 after extracting the payload data from the radio frame.

  The received MAC frame signal s17 input to the buffer control unit 2 is buffered and then output to the input / output port 1 as a received LAN signal s18. Further, the buffer control unit 2 performs Flow control or Back Pressure control by the PAUSE control signal t 11 input from the buffer monitoring unit 3, and outputs a PAUSE frame signal or collision signal from the input / output port 1.

  Next, the operation of the circuit of FIG. 1 will be described with reference to the drawings.

  First, the signal flow in the circuit of FIG. 1 will be described, and then the modulation system switching timing will be described.

  First, a signal flow in the circuit of FIG. 1 will be described.

  After buffering the transmission LAN signal s10 input from the input / output port 1, the buffer control unit 2 outputs the transmission MAC frame signal s11 to the radio frame processing unit 4 and also performs buffer monitoring on the buffer accumulated information signal t10. Output to part 3. In addition, buffering processing is performed on the received MAC frame signal s17 input from the wireless frame processing unit 4, and the received LAN signal s18 is output to the input / output port 1. The buffer control unit 2 corresponds to Flow Control control or Back Pressure control defined by IEEE 802.3x, and in response to the received LAN signal s18 according to the PAUSE control signal t11 input from the buffer monitoring unit 3. Performs PAUSE frame signal and collision signal interrupt control.

  The buffer monitoring unit 3 sets a buffer threshold, which will be described later, in accordance with the radio band change signal t19 input from the adaptive modulation control unit 8, and changes the modulation method based on the buffer accumulation information signal t10 input from the buffer control unit 2 and the buffer threshold. The enable / disable signal t18 and the PAUSE control signal t11 are generated, and the modulation method change enable / disable signal t18 is output to the adaptive modulation control unit 8 and the PAUSE control signal t11 is output to the buffer control unit 2.

  The radio frame processing unit 4 multiplexes the transmission MAC frame signal s11 input from the buffer control unit 2 and the transmission modulation scheme change signal t12 input from the adaptive modulation control unit 8 into a radio frame, and transmits the transmission baseband signal s12. Output to the modem 5. Also, the reception MAC frame signal s17 and the reception modulation method change signal t13 are extracted from the reception baseband signal s16 input from the modem unit 5, and the reception MAC frame signal s17 is applied to the buffer control unit 2 and the reception modulation method change signal t13 is applied. Output to the modulation controller 8.

  The modem unit 5 performs modulation processing on the transmission baseband signal s12 input from the radio frame processing unit 4 and outputs the transmission modulation signal s13 to the radio processing unit 6. Further, demodulation processing is performed on the received demodulated signal s15 input from the wireless processing unit 6, and the received baseband signal s 16 is output to the wireless frame processing unit 4. Here, the modem unit 5 has a bit error detection function for the received demodulated signal s15, and outputs the bit error information signal t14 to the adaptive modulation control unit 8.

  The wireless processing unit 6 performs wireless transmission processing such as DA conversion and frequency conversion on the transmission modulation signal s13 input from the modulation / demodulation unit 5, and transmits the wireless transmission / reception signal s14 from the antenna unit 7. In addition, radio reception processing such as frequency conversion and AD conversion is performed on the radio transmission / reception signal s 14 received from the antenna unit 7, and the reception demodulation signal s 15 is output to the modulation / demodulation unit 5. Here, the radio processing unit 6 has a reception level monitoring function for the radio reception signal s14, and outputs the reception radio level signal t17 to the adaptive modulation control unit 8.

  The modulation scheme determination and the switching of the modulation scheme are controlled by the adaptive modulation control unit 8, and the modulation / demodulation unit 5 and the radio processing unit 6 receive the modulation scheme control signal t 15 and the demodulation scheme control signal input / output from the adaptive modulation control unit 8. In accordance with t16, modulation / demodulation processing and wireless transmission / reception processing are performed.

  The adaptive modulation control unit 8 determines the modulation method of the opposite device from the bit error information signal t14 input from the modem unit 5 and the received radio level information signal t17 input from the radio processing unit 6, and is input from the buffer monitoring unit 3. The modulation scheme switching timing is determined by the modulation scheme change enable / disable signal t18, and the transmission modulation scheme change signal t12 is input to the radio frame processing unit 4 and transferred to the radio facing device. Further, the modulation scheme of the local station apparatus is determined from the reception modulation scheme change signal t13 input from the radio frame processing section 4, and the modulation scheme control signal t15 is output to the modem section 5 and the radio processing section 6. In the wireless transmission device of the present embodiment, it is assumed that an optimum modulation scheme is determined from the bit error information signal t14 and the received radio level information signal t17, and the modulation scheme is switched.

  Next, the switching timing of the modulation method will be described with reference to FIG.

  The buffer monitoring unit 3 has a buffer threshold value for the buffer accumulation amount for each modulation method. When the above-mentioned buffer threshold value is changed from a modulation method with a large multi-value number to a modulation method with a small multi-value number, that is, when the wireless transmission band is reduced, IEEE 802. This is a threshold value that can adjust the packet flow rate of the transmission LAN signal s10 input to the input / output port 1 by Flow Control control or Back Pressure control specified by 3x.

  Below, the calculation method of the above-mentioned buffer threshold value E is demonstrated. The maximum data storage amount of the buffer control unit 3 is A, the current data storage amount is B, the data reading speed of the buffer control unit 2, that is, the wireless transmission band, C, and the data writing speed of the buffer control unit 2, that is, the LAN transmission band is D. To do. Also, the PAUSE frame signal and collision signal generated by the buffer control unit 2 are transmitted from the input / output port 1 and input from the input / output port 1 until packet transmission is stopped by the preceding device connected to the input / output port 1. Let T be the PAUSE control processing time until the transmission LAN signal s10 stops.

At this time, the buffer threshold E is calculated by the following equation.
Buffer threshold E = maximum data storage amount A− (LAN transmission band D−wireless transmission band C) × PAUSE control processing time T

  In the operation example shown in FIG. 2, an operation when the modulation scheme with a large multi-level number is changed to a modulation scheme with a small multi-level number, that is, when the radio transmission band is reduced is described.

  First, the current data storage amount B of the buffer control unit 2 is compared with the above-described buffer threshold value E (step X1). When the data accumulation amount B is smaller than the buffer threshold value E, as described above, the buffer control unit 2 has sufficient free space in the buffer and can absorb the fluctuation of the radio transmission band, so that the modulation method can be changed immediately. (Step X2). When the data accumulation amount B is larger than the buffer threshold value E, the packet of the transmission LAN signal s10 input to the input / output port 1 is executed by executing Flow Control control or Back Pressure control specified by IEEE 802.3x. The flow rate is adjusted (step X3). After executing the above Flow Control control or Back Pressure control, the current data storage amount B of the buffer control unit 2 is compared again with the above buffer threshold value E (step X1).

  In addition, the data read speed of the buffer control unit 2 is changed when the modulation method is changed from the modulation method with a small multi-value number to the modulation method with a large multi-value number, that is, when the wireless transmission band is changed in the increasing direction. Since it becomes faster, the modulation scheme can be changed immediately.

  As described above, the buffer for LAN data is monitored, and the timing for switching the modulation method is adjusted according to the data accumulation amount in the buffer, so that buffer overflow and packet loss are prevented and transmission efficiency is improved. In addition, the buffer control unit 2 does not require a large-sized memory for absorbing the fluctuation of the wireless transmission capacity, and the circuit scale can be reduced.

  As described above, the present embodiment has the following effects.

  The first effect is that, in a wireless transmission apparatus that supports an adaptive modulation system, the amount of buffer overflow is monitored by monitoring the data storage amount of the LAN data input buffer and adjusting the timing of switching the modulation method according to the data storage amount in the buffer. And packet loss are prevented, and transmission efficiency is improved.

  The second effect is to monitor the data accumulation amount of the LAN data input buffer and adjust the timing of switching the modulation method according to the data accumulation amount in the buffer, thereby absorbing the fluctuation of the wireless transmission capacity in the buffer processing unit. Therefore, it is possible to reduce the circuit scale.

<Second Embodiment>
Next, another embodiment of the present invention will be described with reference to FIG.

  Referring to FIG. 3, the buffer control unit 2 shown in FIG. 1 is changed to a QoS (Quality of Service) control unit 9. The input / output port 1, the radio frame processing unit 4, the modulation / demodulation unit 5, the radio processing unit 6, the antenna unit 7, and the adaptive modulation unit 8 shown in FIG. 3 are equivalent to the circuit used in the first embodiment. .

  The QoS control unit 9 reads the label information added to the data area or the header area with respect to the transmission LAN signal s10 input from the input / output port 1, prioritizes after allocation to each class and buffering to each queue. The transmission MAC frame signal s11 is output to the radio frame processing unit 4 in accordance with control and band control. The received MAC frame signal s17 input from the wireless frame processing unit 4 is output from the input / output port 1 as received LAN data s18 after buffering processing.

  The buffer monitoring unit 3 adds a function of monitoring the data accumulation amount for each queue of the QoS control unit 9.

  The radio frame processing unit 4, the modulation / demodulation unit 5, the radio processing unit 6, the antenna unit 7, and the adaptive modulation unit 8 perform the same operations as those described in the first embodiment.

  As described above, in the second embodiment, the data accumulation amount is monitored for each queue and the timing for switching the modulation method is adjusted, so that buffer overflow and packet loss are prevented for each queue, and transmission efficiency is improved. Is realized. Therefore, the present invention is also applicable to a wireless transmission device equipped with QoS control.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to this, and various modifications can be made without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 Input / output port 2 Buffer control part 3 Buffer monitoring part 4 Radio frame processing part 5 Modulation / demodulation part 6 Wireless processing part 7 Antenna part 8 Adaptive modulation control part 9 QoS control part

Claims (6)

A wireless transmission device corresponding to an adaptive modulation method,
Input / output means that is an interface for inputting and outputting data signals of variable transmission speed;
Buffer control means for buffering the data signal input from the input / output means;
Buffer monitoring means for outputting a modulation scheme change enable / disable signal based on a buffer storage information signal inputted from the buffer control means and a predetermined buffer threshold;
Adaptive modulation control means for determining a modulation scheme switching and switching timing of the data signal based on the modulation scheme change enable / disabled signal input from the buffer monitoring means and outputting a modulation scheme control signal when switching the modulation scheme; ,
Modulation / demodulation means for switching the modulation scheme based on the modulation scheme control signal, and modulating the data signal with the switched modulation scheme;
A wireless transmission device comprising: The buffer control means performs bandwidth control related to input / output of the data signal using a plurality of queues,
The radio transmission apparatus according to claim 1, wherein the buffer monitoring unit monitors an accumulation amount of data for the plurality of queues.   The radio transmission apparatus according to claim 1 or 2, wherein the buffer monitoring unit stores the buffer threshold value with respect to the buffer accumulation amount in association with each modulation method switchable by the modulation / demodulation unit. The radio transmission apparatus according to any one of claims 1 to 3, wherein the adaptive modulation control unit calculates the buffer threshold by the following equation and outputs the buffer threshold to the buffer monitoring unit.
E = A− (DC) × T
(Where E is the buffer threshold, A is the maximum data storage amount, D is the transmission band of the input / output means, C is the wireless transmission band, and T is a device connected to the input / output means. (This is the time required for the pause control process from when a signal indicating that signal input / output is paused to when the data signal is actually stopped.) An input unit that is an interface for inputting and outputting a data signal having a variable transmission rate, and a modulation / demodulation unit that performs modulation mode switching based on a modulation mode control signal and modulates the data signal using the switched modulation mode. A method of controlling a wireless transmission device corresponding to an adaptive modulation method,
A buffer control step for buffering the data signal input from the input / output means;
A buffer monitoring step for outputting a modulation scheme change enable / disable signal based on the buffer accumulation information signal input by the buffer control step and a predetermined buffer threshold;
An adaptive modulation control step for determining a modulation scheme switching and switching timing of the data signal based on the modulation scheme change enable / disabled signal input by the buffer monitoring step, and outputting the modulation scheme control signal when switching the modulation scheme; ,
A method for controlling a wireless transmission device, comprising: An input unit that is an interface for inputting and outputting a data signal having a variable transmission rate, and a modulation / demodulation unit that performs modulation mode switching based on a modulation mode control signal and modulates the data signal using the switched modulation mode. Equipped with a wireless transmission device that supports adaptive modulation,
Buffer control processing for buffering the data signal input from the input / output means;
A buffer monitoring process for outputting a modulation scheme change enable / disable signal based on the buffer accumulation information signal input by the buffer control process and a predetermined buffer threshold;
Adaptive modulation control processing for determining modulation scheme switching and switching timing of the data signal based on the modulation scheme change enable / disabled signal input by the buffer monitoring processing, and outputting the modulation scheme control signal when switching the modulation scheme; ,
A program characterized by having executed.

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