JP2006279234A - Radio communication apparatus and control method of radio communication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a time until data transmission completion by suppressing interruption of a third party's terminal into a radio communication band during communication in a radio communication apparatus. <P>SOLUTION: This apparatus has a detecting means for detecting a data processing speed in a communication opposite party's terminal; and a control means for controlling data transmission from start to end of data transmission with the communication opposite party's terminal on the basis of the data transmission speed obtained by the detecting means so that electric field strength within a predetermined distance from a radio communication terminal may be kept at at least a predetermined value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wireless communication apparatus and a wireless communication control method.

In a wireless communication apparatus, transmission is normally performed by selecting a maximum transmission speed that can satisfy a predetermined communication quality from transmission speeds that can be used between wireless communication apparatuses that perform transmission. This is because, in most cases, it is convenient to send data to be transmitted to the communication partner terminal quickly. An example of such a wireless communication system is a wireless LAN (Non-Patent Document 1).
ISO / IEC 8802-11 ANSI / IEEE Std 802.11, Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, 1999

  However, in the above prior art, since the processing speed of the data received at the communication partner (receiving) terminal is not considered, when the data transmission speed in the wireless communication section exceeds the data processing speed of the receiving terminal, The transmission side terminal copes with it by transmitting intermittently. Therefore, a non-communication period occurs in the wireless communication section. A third-party terminal that is controlled to suppress transmission when it is equal to or greater than a predetermined electric field strength as in a wireless LAN determines that transmission is possible when it detects this non-communication period and starts transmission. As a result, until the wireless communication by the third party terminal is terminated or interrupted, the data transmission to the communication partner terminal that was initially performed is forced to be interrupted, and a great deal of time is required until the data transmission is completed.

  The present invention has been made in view of such problems, and its purpose is to suppress interruption to a wireless communication band from a third party terminal during communication with a certain terminal in a wireless communication apparatus, The purpose is to shorten the time until the end of data transmission.

In order to alleviate the above problems, the wireless communication apparatus according to the present invention is:
The detecting means for detecting the data processing speed at the communication partner terminal, and the data processing speed information obtained by the detecting means are used for a period from the start to the end of data transmission within a space of a predetermined distance from the wireless communication device. Control means for controlling the transmission of data so that the electric field strength can be maintained at a predetermined value or higher, and if the electric field strength is higher than the predetermined electric field strength, communication interruptions from other wireless terminals that suppress transmission are reduced. It is characterized by that.

  Here, the data processing speed in the communication partner terminal is derived from the output speed of the data buffer in the communication partner terminal.

  Further, the detection means detects the reception buffer capacity at the communication partner terminal, and the control means controls the data transmission speed by using information on the reception buffer capacity.

  The control means controls the data transmission rate by changing at least one of a modulation scheme and a coding rate.

  Alternatively, the control means controls the data transmission speed by switching between normal data transmission and dummy signal transmission in a time division manner.

  Here, the dummy signal transmission is an unmodulated wave.

In order to alleviate the above problems, the wireless communication method according to the present invention is:
Using the detection process for detecting the data processing speed at the communication partner terminal and the information on the data processing speed obtained by the detecting means, the period from the start to the end of the data transmission is within a predetermined distance from the wireless communication device. A control process for controlling data transmission so that the electric field strength can be maintained at a predetermined value or higher, and communication interruptions from other wireless terminals that suppress transmission when the electric field strength is higher than the predetermined electric field strength are reduced. It is characterized by that.

  ADVANTAGE OF THE INVENTION According to this invention, in a radio | wireless communication apparatus, the time until completion | finish of data transmission can be shortened by suppressing the interruption to the radio | wireless communication band from the third party terminal during communication.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the constituent elements described in this embodiment are merely examples, and are not intended to limit the scope of the present invention only to them.

  Hereinafter, assuming a situation in which image data is transmitted from a digital still camera (DSC) having a wireless LAN communication function to a printer having a wireless LAN communication function and printing is performed, the underlying technology and embodiments of the present invention are described. explain. In FIG. 1, 101 is a DSC, 102 is a printer, and 103 is a PC having a wireless LAN communication function that is not directly involved in the communication between the DSC and the printer.

<Prerequisite technology>
FIG. 2 is a configuration diagram of a wireless communication unit common to the DSC 101, the printer 102, and the PC 103. It is assumed that the wireless communication unit has a communication function compliant with a wireless LAN (IEEE802.11 standard group). 201 is an antenna unit, 202 is a demultiplexing unit that switches between transmission and reception, 203 is a demodulation unit that demodulates a received signal, 204 is a decoding unit that performs error correction of the demodulated data, and 205 temporarily stores data. Data buffer 206 is an encoding unit that encodes transmitted data at a predetermined encoding rate, 211 is an encoding rate control unit that controls the encoding unit 206, and 207 modulates the encoded data using a predetermined modulation method , A modulation scheme control unit that controls the modulation unit 207, a baseband unit through which data to be transmitted / received flows, and a device-specific function unit having functions specific to the device (an imaging unit, printer if a camera) If so, the printing section or the like. Reference numeral 213 denotes a CPU that controls the entire wireless communication unit, reference numeral 214 denotes a RAM, and reference numeral 215 denotes a ROM that stores a transmission / reception program for transmitting / receiving data.

  Next, the operation of the data buffer 205 at the time of data reception will be described with reference to FIG. Here, as an example, it is assumed that the data buffer 205 includes eight memory blocks A to H. Data output from the decoding unit 204 is first input to the memory A, and sequentially transferred as B, C, D... H according to a clock (not shown) input to the data buffer 205. Here, the transfer operation speed is determined by the input clock speed. When the data buffer 205 becomes full (data exists in all memory blocks A to H), the data is output at the speed of the input clock. When the data buffer 205 is full, new data cannot be input, and input is waited until a memory block is available.

  Therefore, depending on the transfer operation speed in the data buffer 205, the substantial data transmission speed may not increase regardless of the transmission speed in the wireless communication section. For example, the maximum transmission speed of wireless LAN (for example, 54 Mbps in 802.11g) is sufficiently larger than the data processing speed of a general printer (for example, 5 Mbps). That is, the input transfer rate in the data buffer 205 in the printer 102 is faster than the output transfer rate to the device specific function unit 210 (here, the printing unit) via the baseband unit 208. If the amount of data is small compared to the amount of data received, the buffer becomes full after a certain time from the start of communication (buffer capacity / (input transfer rate−output transfer rate)).

  The time change of the communication state in the wireless communication unit of the DSC 101 will be described with reference to FIG.

The DSC 101 executes a transmission / reception program in the CPU 213, for example, selects the maximum transmission rate that can satisfy the predetermined communication quality in the wireless communication section, and starts transmission. (T1)
When the buffer becomes full in the printer 102, for example, the flow control function of the transmission / reception program executed in the CPU 213 notifies the DSC 101 that the buffer is full, and the DSC 101 temporarily stops transmission. (T2)
When the buffer becomes empty in the printer 102 after a predetermined time has elapsed, for example, the flow control function of the transmission / reception program executed in the CPU 213 notifies the DSC 101 that the buffer is empty, and the DSC 101 resumes data transmission. To do. (T3)
In the printer 102, when the buffer becomes full again, the DSC 101 is notified that the buffer is full, and the DSC 101 temporarily stops transmission again. (T4)
The above operation is repeated until the end of data transmission.

  In the transmission pause state (non-transmission state) of the DSC 101, since the printer 102 is also in the non-transmission state, the wireless communication section is unused. That is, the PC 103 which is a third party terminal is in a state where transmission can be started (that is, interruptible) at an arbitrary time.

(First embodiment)
As a first embodiment of a wireless communication apparatus according to the present invention, a DSC 101 having a wireless LAN communication function will be described as an example.

  Except for the point that the transmission control program stored in the ROM 215 is different, the apparatus configuration is substantially the same as the apparatus configuration described in the base technology (FIG. 2), and the description thereof will be omitted. Hereinafter, each component of the wireless communication unit of the printer 102 uses the same 2XX as the reference symbol in FIG. 2, and each component of the wireless communication unit of the DSC 101 changes the reference symbol in FIG. 2 to 3xx. I will explain.

  The DSC 101 can acquire the data buffer output speed in the data buffer 205 of the printer 102 from the printer 102 by using an inquiry command or the like. This inquiry function can be realized by a conventional software program or the like, and may be incorporated in a transmission control program stored in the ROM 215.

<Operation of the device>
FIG. 5 shows a flowchart of the operation of the DSC 101 in the first embodiment.

  The DSC 101 starts a flow for transmitting image data to the printer in order to print the captured image data.

  In step S501, first, the DSC 101 and the printer 102 establish a wireless link.

  In step S502, after the wireless link is established, the DSC 101 transmits a signal inquiring about the buffer output speed of the printer 102. The printer 102 in the receiving state receives a signal for inquiring about the data buffer output speed from the DSC 101 via the demodulator 203 and the decoder 204, and the CPU 213 acquires data buffer output speed information from the data buffer 205, A signal including data buffer output speed information is transmitted to the DSC 101 via the encoding unit 206 and the modulation unit 207.

  In step S503, the DSC 101 in the receiving state receives a signal including information on the data buffer output speed from the printer 102 via the demodulator 303 and the decoder 304, and the CPU 313 receives information on the data buffer output speed of the printer 102. Is acquired and stored in the RAM 314.

  In step S504, the CPU 313 of the DSC 101 refers to the data buffer output speed information of the printer 102 stored in the memory 314 so that the data buffer 205 of the printer 102 does not become full (that is, approximately the same as the data buffer output speed). The coding rate and the modulation method to be the speed are determined and set in the coding unit 306 and the modulation unit 307 via the coding rate control unit 311 and the modulation method control unit 312. In determining the coding rate and the modulation method, it is desirable to determine the coding rate and the modulation method that are slightly higher than the data buffer output speed of the printer 102 in consideration of the fact that the actual transmission speed decreases depending on the use environment. I do.

  In step S505, the DSC 101 starts transmitting image data.

  In step S506, the DSC 101 determines whether or not the image data to be transmitted has ended, and if it has ended, the flow ends.

  In step S507, it is determined whether or not a buffer full notification signal of the data buffer 205 has been received from the printer 102 after the start of data transmission at the time until the image data to be transmitted ends. If not, the process proceeds to S506. Return.

  If a buffer full notification signal is received, the data transmission is temporarily stopped in step S508, and the coding rate and modulation are lower than the coding rate and modulation method determined in step S504 in step S509. The system is re-determined, data transmission is resumed in step S510, and the process returns to step S506.

  The above operation is repeated until the image data to be transmitted is completed.

<Change in communication status over time>
FIG. 6 shows a schematic diagram of the time change of the communication state in the DSC 101 in the above-described operation.

  The DSC 101 transmits data at a low speed (illustrated by a solid line) as compared with the original communication speed (illustrated by a dotted line) so that the data buffer 205 of the printer 102 does not become full. Since the communication between the DSC 101 and the printer 102 continues almost seamlessly along the horizontal axis (time axis), the PC 103, which is a third-party terminal that suppresses transmission when the electric field strength exceeds a predetermined value, cannot start transmission. . Therefore, the DSC 101 can continuously transmit data without receiving a communication interruption by a third party terminal until the end of data. 6 is the time when the printer 102 notifies the DSC 101 whether the data buffer is empty or full, that is, the period during which the printer 102 is transmitting.

  As described above, in the wireless communication device, it is possible to perform continuous communication in time by determining the transmission speed based on the data buffer output speed information of the counterpart terminal during communication with the counterpart terminal. Thus, no communication state in the wireless communication section does not occur. Therefore, it is possible to reduce interruption to the wireless communication band from a third party terminal that suppresses transmission when the electric field strength is greater than or equal to a predetermined value, and to shorten the time until the end of data transmission. In this embodiment, the coding rate and modulation method are determined using only the data buffer output speed, and transmission is performed. However, by further utilizing the data buffer capacity information in the printer 102, the data buffer is The communication time can be further shortened by transmitting data up to the capacity at the highest speed.

  Further, by reducing the data communication transmission speed, there is an effect that the power consumption of the DSC 101 and the printer 102 is also reduced.

(Second Embodiment)
As a second embodiment of the wireless communication apparatus according to the present invention, a DSC 101 having a dummy signal transmission function will be described below as an example. Except for the point that the transmission control program stored in the ROM 215 is different, the apparatus configuration is substantially the same as the base configuration and the apparatus configuration (FIG. 2) described in the first embodiment, and a description thereof will be omitted. Further, hereinafter, each component of the wireless communication unit of the printer 102 uses the same 2XX as the reference symbol in FIG. 2, and each component of the wireless communication unit of the DSC 101 changes the reference symbol in FIG. 2 to 3xx. I will explain.

  The DSC 101 can acquire the data buffer output speed and buffer capacity in the data buffer 205 of the printer 102 from the printer 102 by using an inquiry command or the like. This inquiry function can be realized by a conventional software program or the like, and may be incorporated in a transmission control program stored in the ROM 215.

<Operation of the device>
FIG. 7 shows a flowchart of the operation of the DSC 101 in the second embodiment.

  The DSC 101 starts a flow for transmitting image data to the printer in order to print the captured image data.

  In step S701, first, the DSC 101 and the printer 102 establish a wireless link.

  In step S <b> 702, after the wireless link is established, the DSC 101 transmits a signal inquiring about the buffer output speed and buffer capacity of the printer 102. The printer 102 in the receiving state receives a signal for inquiring about the data buffer output speed from the DSC 101 via the demodulator 203 and the decoder 204, and the CPU 213 acquires data buffer output speed information from the data buffer 205, A signal including data buffer output speed and buffer capacity information is transmitted to the DSC 101 via the encoder 206 and the modulator 207.

  In step S703, the DSC 101 in the receiving state receives a signal including information on the data buffer output speed and buffer capacity from the printer 102 via the demodulator 303 and the decoder 304, and the CPU 313 outputs the data buffer of the printer 102. Information on speed and buffer capacity is acquired and stored in the RAM 314.

  In step S704, the CPU 313 of the DSC 101 determines a coding rate and a modulation scheme that provide a maximum transmission rate that can satisfy predetermined communication quality with the printer 102, and a coding rate control unit 311 and a modulation scheme control unit. The data is set in the encoding unit 306 and the modulation unit 307 via 312.

  In step S705, the DSC 101 starts transmitting image data, and transmits data only for a period derived from the data buffer capacity and the transmission rate. Desirably, the period is obtained by dividing the data buffer capacity by the transmission rate.

  In step S706, the DSC 101 determines whether or not a buffer full notification signal for the data buffer 205 has been received from the printer 102 at the time until the image data to be transmitted ends. If not, the process proceeds to step S707.

  In step S707, the DSC 101 determines whether or not the image data to be transmitted has ended, and if it has ended, the flow ends.

  In step S708, a dummy signal is transmitted for a predetermined period derived from the data buffer capacity and the data buffer output speed. Desirably, the period is obtained by dividing the data buffer capacity by the data buffer output speed. Here, the dummy signal is a signal transmitted to increase the electric field strength in order to indicate to other terminals that the wireless communication section is being used with respect to the receiver without taking the form of a normal data transmission signal. is there. Although any signal can be used as the dummy signal, it is more preferable to use an unmodulated signal that can output the dummy signal with less power consumption than the modulated signal. After transmitting the dummy signal for a predetermined time, the process returns to step S705.

  If a buffer full notification signal is received in step S706, a dummy signal is transmitted for a predetermined period immediately after the data transmission is temporarily stopped in step S709. Note that the transmission period here is the same as or shorter than the transmission period of the dummy signal in step S708. When the dummy signal transmission ends, the process returns to step S705.

  The above operation is repeated until the image data to be transmitted is completed.

<Change in communication status over time>
FIG. 8 shows a schematic diagram of the time change of the communication state of the DSC 101 in the above-described operation.

  The DSC 101 transmits a dummy signal after transmission at the maximum speed. For this reason, the wireless section between the DSC 101 and the printer 102 continues almost seamlessly along the horizontal axis (time axis) by data communication and dummy signal transmission. Therefore, if the electric field strength exceeds a predetermined value, transmission is suppressed. The PC 103 which is a three-party terminal cannot start transmission. Therefore, the DSC 101 can continuously transmit without receiving a communication interruption by the third party terminal until the end of data.

  As described above, in the wireless communication device, the data signal and the dummy signal are transmitted in a time division manner based on the information on the data buffer output speed and the buffer capacity of the partner terminal during communication with the partner terminal. A non-communication state (period in which the electric field intensity is less than or equal to a predetermined value) does not occur in the communication section. Therefore, it is possible to reduce interruption to the wireless communication band from a third party terminal that suppresses transmission when the electric field strength is greater than or equal to a predetermined value, and to shorten the time until data transmission ends. In the present embodiment, the transmission period is uniquely determined and described based on the data buffer output speed and buffer capacity and the data transmission speed information in the printer 102. However, the transmission time of the data signal and the dummy signal is as described above. The description is not limited. Note that the power consumption of the printer in the state where the dummy signal is transmitted can be smaller than that in the normal data reception state, which contributes to a reduction in power consumption.

It is the figure which showed the state which DSC and a printer are communicating. It is a block diagram of a radio | wireless communication part. It is operation | movement explanatory drawing of a data buffer. It is the figure which showed the time change of the communication state of DSC in a base technology. It is an operation | movement flowchart of DSC in 1st Embodiment of this invention. It is the figure which showed the time change of the communication state of DSC in 1st Embodiment of this invention. It is an operation | movement flowchart of DSC in 2nd Embodiment of this invention. It is the figure which showed the time change of the communication state of DSC in 2nd Embodiment of this invention.

Claims (7)

A wireless communication device,
Detecting means for detecting a data processing speed in the communication partner terminal;
Based on the data processing speed obtained by the detection means, at least a predetermined electric field strength within a predetermined distance from the wireless communication device during a period from the start to the end of data transmission with the communication partner terminal. Control means for controlling the transmission of data so as to hold the value;
And a communication interruption from another wireless communication terminal that suppresses transmission when the electric field intensity is equal to or more than the predetermined value.   2. The wireless communication apparatus according to claim 1, wherein the detecting unit detects the data processing speed at the communication partner terminal based on an output speed of a data buffer at the communication partner terminal. The detection means further detects a data buffer capacity in the communication partner terminal,
The wireless communication apparatus according to claim 1, wherein the control unit further controls a data transmission rate based on the information on the data buffer capacity.   4. The wireless communication apparatus according to claim 1, wherein the control unit controls at least one of a modulation scheme and a coding rate to control a data transmission rate. 5.   4. The wireless communication apparatus according to claim 1, wherein the control unit switches between normal data transmission and dummy signal transmission in a time division manner.   6. The wireless communication apparatus according to claim 5, wherein the dummy signal transmission is an unmodulated wave. A wireless communication method,
A detection step of detecting a data processing speed in the communication partner terminal;
Based on the data processing speed obtained by the detection means, at least a predetermined electric field strength within a predetermined distance from the wireless communication device during a period from the start to the end of data transmission with the communication partner terminal. A control process for controlling the transmission of data so as to hold the value;
And a communication interruption from another wireless communication terminal that suppresses transmission when the electric field intensity is equal to or more than the predetermined value.

Images