JP3920825B2 - Transmission speed determination method and terminal device using the same - Google Patents

Description

  The present invention relates to a transmission rate determination technique. In particular, the present invention relates to a transmission rate determination method for changing a transmission rate and a terminal device using the transmission rate determination method.

  In a wireless communication system, the transmission path environment varies with time. One of the techniques for increasing the transmission speed under such a transmission path environment is an adaptive modulation scheme. The adaptive modulation scheme controls the modulation scheme according to the transmission path environment.For example, when it is determined that the transmission path environment is bad, the data is transmitted using a highly reliable modulation scheme, When it is determined that the transmission path environment is good, data is transmitted using a modulation method with a large amount of information (see, for example, Patent Document 1).

  When a base station apparatus and a terminal apparatus included in a wireless communication system communicate with each other using a TDD (Time Division Duplex) method, generally, uplink slots and downlink slots are regularly transmitted alternately. The

  Each slot includes a preamble used for estimating the transmission path environment, modulation scheme information indicating a modulation scheme used for transmission, and information symbols. When the reversibility of the transmission path is established in the TDD scheme, the base station apparatus receives the slot, and receives the received baseband signal and the reception level information such as RSSI (Received Signal Strength Indicator) and the C / N (Carrier to Noise) of the transmission path. (Ratio), delay spread, and the like are detected, and the transmission path environment at the next transmission timing is estimated. Further, a modulation scheme to be used for transmission is selected according to the estimation result.

  As a result, the transmission speed is ideally suited to the transmission path quality. However, the actual transmission path environment varies depending on the movement of the terminal device or the like, and the modulation scheme suitable for actually transmitting a signal may be different from when the transmission path quality is measured.

In particular, when transmitting or receiving important information related to communication control such as a disconnection request or an emergency message from a terminal device, the occurrence of a transmission error or retransmission may affect the control of the entire communication system. . Therefore, the present applicant has proposed a device for selecting an adaptive modulation method in accordance with the importance of a control signal to be transmitted and received in Japanese Patent Application No. 2003-146052.
JP 2002-290246 A

  Under such circumstances, the inventor has come to recognize the following problems.

  When the control signal to be transmitted / received is a highly important signal, by selecting a highly reliable modulation method that is unlikely to cause a transmission error, it is possible to suppress the occurrence of retransmission and perform more reliable transmission. However, for data controlled by higher-level applications such as e-mail and homepage browsing, the occurrence frequency and size vary depending on the operation of the application, and the influence on the operation can be specified uniformly. It is very difficult.

  In particular, when data is rarely generated and the size of the data is small, if a modulation scheme switching procedure for performing adaptive modulation is executed every time data is generated, the period required for the switching procedure Becomes longer and the transmission efficiency decreases. Furthermore, if the transmission path quality deteriorates from when the transmission path quality is measured to when the signal is actually transmitted, the data is retransmitted due to the occurrence of a transmission error despite the small data, Transmission efficiency is further reduced.

  The present inventor has recognized the above situation and made the present invention. The purpose of the present invention is to determine the transmission rate in consideration of the size of data to be transmitted and received when performing data communication at a variable transmission rate. It is to provide a terminal device using the same.

One embodiment of the present invention is a terminal device. This device includes a communication unit that communicates data with a base station device at a variable transmission rate, a reception data size acquisition unit that obtains information about the size of data to be received prior to data reception via the communication unit, and a reception A transmission rate determining unit that determines a transmission rate with the base station apparatus according to the size of data to be transmitted; and a transmission rate requesting unit that requests the base station device to transmit data at the determined transmission rate. .

  When receiving data from a predetermined communication partner with the above apparatus, the data size is obtained in order to obtain the size of the data to be received and determine the modulation method in accordance with the size before receiving the data. Is small, a highly reliable modulation scheme that is less likely to cause transmission errors is fixedly used, and stable data communication can be realized.

  A transmission path quality measuring unit for measuring a transmission path quality with the base station apparatus, and a transmission rate deriving section for deriving a transmission speed candidate with the base station apparatus according to the measured transmission path quality If the size of the data to be received is smaller than the threshold, the speed determination unit determines the predetermined transmission speed as the transmission speed with the base station apparatus, while the size of the data to be received is equal to or greater than the threshold In this case, the derived candidate transmission rate may be determined as the transmission rate with the base station apparatus.

  Another aspect of the present invention is also a terminal device. This device includes a communication unit that communicates data with a base station device at a variable transmission rate, a measurement unit that receives data to be transmitted and measures the size of data to be transmitted, and the size of the measured data to be transmitted. Accordingly, a transmission rate determining unit that determines a transmission rate with the base station device, and a transmission rate requesting unit that requests the base station device to transmit data at the determined transmission rate.

  Even when data is transmitted to a predetermined partner using the above apparatus, the size of data to be transmitted is calculated prior to data transmission, and the modulation scheme corresponding to the size is determined. In this case, a highly reliable modulation system that hardly causes transmission errors is fixedly used, and stable data communication can be realized.

  When the transmission rate determined by the transmission rate determination unit is the same as the transmission rate currently set with the base station device, the transmission rate request unit changes the transmission rate to the base station device. You may make a request not to do so.

  Another aspect of the present invention is a transmission rate determination method.

  In this method, in a terminal device, information on the size of data to be received is received from the base station device that communicates at a variable transmission rate, and the base station device is in accordance with the information on the obtained size. The base station apparatus is requested to transmit data at the determined transmission speed.

  With the above method, when receiving data from a predetermined communication partner, the size of the data to be received is obtained prior to the data reception, and the modulation method is determined according to the size. Is small, a highly reliable modulation scheme that is less likely to cause transmission errors is fixedly used, and stable data communication can be realized.

  Another aspect of the present invention is also a transmission rate determination method.

  In this method, in a terminal device, the size of data to be transmitted to a base station device communicating at a variable transmission rate is measured prior to data transmission, and the base station device is determined according to the size of data to be transmitted. The base station apparatus is requested to transmit data at the determined transmission speed.

  Even when data is transmitted to a predetermined partner by the above method, the size of data to be transmitted is calculated prior to data transmission, and the modulation method is determined accordingly. In this case, a highly reliable modulation system that hardly causes transmission errors is fixedly used, and stable data communication can be realized.

  Another aspect of the present invention is a program.

  This program obtains information about the size of data to be received from a base station apparatus that communicates at a variable transmission rate via a wireless network and stores the information in a memory, and the size stored in the memory. And determining a transmission rate with the base station apparatus in response to the information regarding, and requesting the base station apparatus to transmit data at the determined transmission rate via the wireless network.

  Another embodiment of the present invention is also a program.

  This program measures the size of data to be transmitted to a base station apparatus that communicates at a variable transmission rate, and stores it in a memory through the interface with the program that generated the data to be transmitted before the data is transmitted. Determining a transmission rate with the base station apparatus according to the size of data stored in the memory, and requesting the base station apparatus to transmit data at the determined transmission rate via the wireless network Including.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

According to the present invention, when receiving data from a predetermined communication partner, the terminal apparatus obtains the size of data to be received prior to receiving the data, and determines the modulation method according to the size. For this reason, when the amount of data is small, a highly reliable modulation system that is unlikely to cause a transmission error is fixedly used, and stable data communication can be realized.

  In addition, when transmitting data to a predetermined partner, the terminal device calculates the size of data to be transmitted prior to data transmission, and determines the modulation method according to the data size. , A highly reliable modulation scheme that is less likely to cause transmission errors is fixedly used, and stable data communication can be realized.

The present embodiment relates to a communication system that performs adaptive modulation between a terminal apparatus and a base station apparatus according to the environment of the transmission path. The terminal apparatus receives data prior to reception when receiving data. If the information regarding the size of the data to be obtained is obtained and the size is smaller than the threshold value, the base station device should use the modulation method predetermined by the terminal device as the modulation method of the signal to be transmitted. Request to the station equipment. In addition, when data is to be transmitted, the terminal device measures the size of the data to be transmitted. If the size of the data to be transmitted is smaller than the threshold value, the terminal device transmits the data. The base station apparatus is requested to use in a fixed manner a modulation method predetermined by the terminal device as a modulation method of the power signal.

  FIG. 1 shows a communication system according to the present embodiment. The communication system 10 includes a terminal device 100, a base station device 200, and a network 300.

  In addition, the terminal device 100 includes an application control unit 101, a wireless communication control unit 102, a communication data amount determination unit 103, a modulation / demodulation unit 104, a quality measurement unit 105, a modulation scheme determination unit 106, and a radio unit 107. A terminal antenna 108 and a control unit 109.

  The application control unit 101 is a control unit that performs browsing of e-mail and WWW (World Wide Web) homepages, receives instructions from the user such as transmission / reception of e-mails and homepage display, etc., to the wireless communication control unit 102 described later. On the other hand, the communication path is instructed to connect or disconnect, and the size of the data to be received or the data to be transmitted is acquired or measured and output to the communication data amount determination unit 103 described later. The “communication path” is a signal line for data transmission that is set between the terminal device 100 and a communication partner to which the terminal device 100 is connected in order to send and receive e-mails and browse home pages. In addition to the wireless communication section to the base station apparatus, all communication sections from the base station apparatus to the communication partner are included.

  The radio communication control unit 102 exchanges messages related to radio channel allocation and adaptive modulation with the base station apparatus 200 in response to a request for connection or disconnection of a communication path instructed by the application control unit 101. In addition, the communication channel with the communication partner is set.

  The communication data amount determination unit 103 receives information on the size of data to be transmitted or received from the application control unit 101, and the size is stored in a predetermined size (not shown) (not shown). Hereinafter, it is determined whether it is larger or smaller (referred to as a threshold value), and the determination result is output to a modulation scheme determination unit 106 described later.

  The modem unit 104 modulates information to be transmitted and demodulates received information. Here, for example, the terminal device 100 having an adaptive modulation function includes a plurality of modulation schemes (π / 4 shift QPSK: Quadrature Phase Shift Keying, 16QAM: Quadrature Amplitude Modulation), and instructions from the base station device 200 It shall be changed adaptively according to the notice. The modulation / demodulation method is determined by an instruction from the base station device 200 with respect to the modulation method (uplink signal from the terminal device 100 to the base station device 200), and the demodulation method (base station device 200 to the terminal device 100). Is determined by a response signal of the base station apparatus 200 to the request signal from the terminal apparatus 100 to the base station apparatus 200.

  The quality measuring unit 105 appropriately measures the quality of the received signal. The quality of the received signal may be arbitrary, but here, the signal demodulated by the modem unit 104 or the strength of the desired signal received from the RSSI (Received Signal Strength Indicator), the received interference signal Measure intensity, ratio of desired signal to interference signal, etc. Alternatively, the error rate of the signal demodulated by the modem unit 104 may be measured.

  In accordance with the determination result regarding the data size from the communication data amount determination unit 103, the modulation method determination unit 106 uniquely determines a predetermined modulation method when the data size is smaller than the threshold value, When the data size is larger than the threshold value, the modulation method corresponding to the measured quality is determined from the quality of the signal measured by the quality measuring unit 105. Hereinafter, as an example of determining the modulation method from the quality measured by the quality measuring unit 105, a case where the quality of the signal is the intensity ratio between the desired signal and the interference signal will be described. FIG. 2 shows an example of a table used when determining the modulation method. A reference value “A” is defined and stored in advance, and if the measured intensity ratio is equal to or greater than the reference value “A”, the modulation method is determined to be 16QAM capable of transmitting a large amount of information and measured. If the intensity ratio is less than the reference value “A”, the modulation method is determined to be π / 4 shift QPSK capable of highly reliable transmission.

  In the transmission, the radio unit 107 DA-converts the baseband signal processed by the modem unit 104, converts the frequency to a radio frequency, amplifies it, and transmits it from an antenna described later. In reception, the signal input from the antenna is amplified by an LNA (Low Noise Amplifier), then frequency-converted to a baseband frequency, AD-converted, and output to the modem unit 104 as a baseband signal. To do.

  The terminal antenna 108 transmits and receives radio frequency signals. Note that the terminal antenna 108 may be any of an omnidirectional antenna, a predetermined directional antenna, and an adaptive array antenna, and may have a diversity function.

  The control unit 109 executes timing processing, control signal processing, and the like of the terminal device 100.

  This configuration can be realized in terms of hardware by a CPU, memory, or other LSI of an arbitrary computer, and in terms of software, it is realized in advance by a program stored in a memory (not shown) and read out at the time of execution. Here, functional blocks realized by the cooperation are depicted. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  FIG. 3 shows a frame format according to the embodiment. In the frame format, a plurality of frames are continuously arranged. Here, this is indicated by “frame 1” to “frame 100”, but a frame (not shown) is also arranged before and after that. One frame is composed of eight time slots, and has the same configuration as that of the simple mobile phone system. Here, this is indicated by “slot 1” to “slot 8”.

  Further, of the eight time slots, four time slots, that is, “slot 1” to “slot 4” are used for the downlink, and the remaining four channels, that is, “slot 5” to “slot 8”. Is used for the uplink.

  FIG. 4 is a flowchart showing a processing procedure of the terminal device 100 when receiving an electronic mail.

  A case will be described in which the terminal device 100 is connected to a mail server via the base station device 200 and receives an e-mail addressed to its own terminal.

  When receiving an e-mail reception instruction from the user, the application control unit 101 of the terminal device 100 requests the wireless communication control unit 102 to establish a communication path.

  In response to the communication channel connection request, the wireless communication control unit 102 first receives a wireless channel assignment from the base station device 200 via the wireless unit 107, establishes synchronization on the channel, and then sends a mail via the network 300. Connection to the server is performed (S401).

  When the connection of the communication path is completed, the application control unit 101 confirms whether there is a new mail addressed to its own terminal with respect to the mail server (S402).

  If there is a mail (Y in S402), information on the list and size of the mail is obtained (S403), and the mail received from the list is selected (S404).

  When the selection of the mail to be received is completed, the application control unit 101 calculates the total size of the selected emails (the total size when there are a plurality of emails) and outputs it to the communication data amount determination unit 103. At the same time, the data size determination is instructed (S405).

  In response to the determination instruction, the communication data amount determination unit 103 compares a predetermined threshold value with the size transmitted from the application control unit 101, and outputs the size to the modulation scheme determination unit 106.

  Then, the modulation scheme determination unit 106 to which the size determination result is transmitted from the communication data amount determination unit 103 makes a request to the base station apparatus 200 when the data size is smaller than the threshold value (N in S405). The modulation method is uniquely determined as a predetermined modulation method (for example, π / 4 shift QPSK) (S406). On the other hand, when the data size is larger than the threshold value (Y in S405), the processing related to adaptive modulation is performed. And the modulation scheme selected according to the result is determined as the modulation scheme to be requested to the base station apparatus 200.

  When the communication data amount determination unit 103 reports that the data size is larger than the threshold value, the modulation scheme determination unit 106 inputs the quality information of the transmission path that the quality measurement unit 105 is measuring timely (S407). If the transmission channel quality is equal to or higher than a specified value (for example, when it is determined that the transmission channel quality is equal to or higher than “A” shown in FIG. 2) (Y in S408), the modulation method is determined to be 16QAM (S409). If it is inferior to the specified value (for example, when judged to be less than “A” shown in FIG. 2) (N in S408), the modulation method is determined to be a predetermined π / 4 shift QPSK (S406).

  When the determined modulation scheme is transmitted to radio communication control section 102 and modulation / demodulation section 104, radio communication control section 102 requests base station apparatus 200 to communicate with the determined modulation scheme (S410), and currently communicates. If it is different from the modulation scheme being used, the modulation scheme is switched after waiting for a response from the base station apparatus 200.

  As a result of these operations, the modulation method is determined, and when synchronization is established with the modulation method, the application control unit 101 receives the selected mail from the mail server (S411). (S412).

  When the deletion of the mail is completed, the connection with the mail server is disconnected (S413), the wireless communication control unit 102 is instructed to disconnect the wireless line, and the series of operations ends.

  The selection of the received mail in the present embodiment is related to the mail obtained by the process by the application control unit 101 in addition to the method of displaying a list of mails for the user and accepting some of the mails from the list. Various selection methods such as emails from information, emails from specific senders, emails of a predetermined size or less, emails with important indications, or emails with new date information can be realized. It doesn't matter.

  FIG. 5 is a sequence diagram of a reception protocol (POP: Post Office Protocol) of an electronic mail transmitted / received to / from a mail server when the electronic mail described in FIG. 4 is received.

  When the application control unit 101 of the terminal device 100 is connected to the mail server via the base station device 200, it establishes a TCP (Transmission Control Protocol) connection (S501).

  When the TCP connection is established, the application control unit 101 obtains ID information (USER) (S502) and a password (PASS) related to user authentication for identifying a user, which has been negotiated with the mail server in advance. Transmit (S504).

  When the user authentication and the password are confirmed, the mail server returns a response (OK) (S503, S505) to notify that it has been authenticated.

  Now, after confirming the user authentication, the application control unit 101 of the terminal device 100 transmits a message (STAT) for confirming the state to the mail server in order to confirm the presence / absence of mail addressed to the terminal itself (S506). In this state confirmation, the mail server returns the presence / absence of mail addressed to its own terminal, and if so, the number and the size of all data (S507).

  When there are a plurality of mails addressed to the terminal itself, the application control unit 101 that has obtained this information transmits a mail list and a message (LIST) requesting related information to the mail server (S508), As a response, detailed information for each mail (title, sender, size, presence / absence of attached file, etc.) is received from the mail server (S509), the mail to be actually received is selected from the information, and the received data Is calculated (S510).

  When there is only one received mail or when all mails are received even if there are many mails, the size of the data received by S507 is known, so the list request (LIST) to the mail server can be omitted. It is.

  When the selection of the mail to be received and the total size thereof are calculated, the modulation scheme according to the size information and the quality of the transmission path is determined, and the modulation scheme on the radio line is performed by processing with the base station apparatus 200 Set.

  When the modulation method is determined and the switching process is performed, the application control unit 101 transmits a message (RETR) requesting reception of an e-mail to the mail server (S511), and receives the selected mail as a response. (S512). When reception of the selected mail is completed, the received mail is deleted (DELE) from the mail server (S513, S514), a termination message (QUIT) is transmitted, and the TCP connection with the mail server is disconnected (S515). , S516).

  FIG. 6 is a sequence diagram in the case where the data size is larger than the threshold value and adaptive modulation processing is executed in the processing of the wireless section related to the reception of the electronic mail of the terminal device. This process is a sequence indicating a wireless section connection between the terminal apparatus 100 and the base station apparatus 200, and before the terminal apparatus 100 receives an e-mail, before connecting to a mail server (establishing a TCP connection). This corresponds to a wireless connection process with the base station apparatus 200 and an adaptive modulation process sequence after the start of communication.

  When the user of the terminal apparatus 100 is instructed to receive an e-mail via the application control unit 101, the radio communication control unit 102 requests the base station apparatus 200 to allocate a radio channel “LCH (Link Channel)”. An “establishment request” message is generated and transmitted to the base station apparatus 200 (S601).

  The base station apparatus 200 confirms the availability status of the radio channel, and returns an “LCH allocation” message if there is a vacancy (S602).

  The terminal apparatus 100 transmits a synchronization burst on the assigned radio channel (S603), and the base station apparatus 200 also returns a response of the synchronization burst to the terminal apparatus 100 to establish a link channel with each other. Plan.

  If synchronization is established and information can be exchanged on the radio channel allocated between the terminal apparatus 100 and the base station apparatus 200, the terminal apparatus 100 and the base station apparatus 200 can process each other. A function negotiation including processing such as exchanging information is executed (S605), and a communication state is reached (S606).

  Note that the modulation scheme used in the first communication state immediately after the function negotiation is not known because the quality of the transmission path is unknown, so that all devices regardless of the correspondence to the adaptive modulation scheme of the terminal apparatus 100 and the base station apparatus 200. Is a common π / 4 shift QPSK.

  The terminal device 100 that has reached the communication state establishes a TCP connection with the mail server and confirms whether or not there is a mail to be received by the processing procedure described with reference to FIG. 4 and FIG. Is present, the size information is acquired (S607).

  When the size of the mail to be received is larger than a predetermined threshold value, the modulation scheme determination unit 106 activates adaptive modulation processing. Specifically, the modulation scheme determining unit 106 inputs the quality information of the received signal that is continuously monitored by the quality measuring unit 105, and when the quality exceeds a predetermined value (for example, in FIG. 2). 16QAM capable of transmitting a larger amount of information as the modulation method, on the contrary, when the quality is less than a specified value (for example, less than “A” shown in FIG. 2) Π / 4 shift QPSK with less occurrence of transmission error as a modulation method is determined and transmitted to the wireless communication control unit 102 and the modem unit 104.

  The radio communication control unit 102 generates a “transmission path quality notification signal” message requesting data transmission using the determined modulation method, and transmits the message to the base station apparatus 200 via the radio unit 107 (S608). On the other hand, when receiving the message, the base station apparatus 200 confirms whether or not the response is possible, and returns a “modulation method notification signal” message (S609) informing the switching of the modulation method if the response is possible.

  Now, when the terminal apparatus 100 receives the “modulation method notification signal” message returned from the base station apparatus 200, the terminal apparatus 100 performs a switching process of the modulation system with the base station apparatus 200 (S610), and a new modulation system ( After reaching the communication (S611) by 16QAM), the receiving operation of the selected mail is executed.

  FIG. 7 is a sequence diagram in the case where the data size is smaller than the threshold value and the adaptive modulation processing is stopped in the processing of the radio section related to the reception of the e-mail of the terminal device.

  Note that the function negotiation and the sequence (S701 to S706) up to the communication immediately after that are the same as those in FIG. 6 (S601 to S606), and thus the description thereof is omitted.

  The terminal device 100 that has reached the communication state establishes a TCP connection with the mail server and confirms whether or not there is a mail to be received by the processing procedure described with reference to FIG. 4 and FIG. If there is, size information is acquired (S707).

  When the size of the mail to be received is smaller than a predetermined threshold, the modulation scheme determining unit 106 determines the modulation scheme to be used as a preset modulation scheme (for example, π / 4 shift QPSK). In addition, a comparison with the modulation method currently used for communication is performed.

  As a result of this comparison and confirmation, if the modulation scheme currently in communication is the same as the preset modulation scheme (the example shown in FIG. 7 is a sequence immediately after the start of communication, the modulation scheme in communication is preset. The wireless communication control unit 102 requests the base station apparatus 200 to prohibit switching from the current modulation method, assuming that the modulation method is the same. The "modulation method change prohibition signal" message is transmitted (S708).

  The base station apparatus 200 that has received the message monitors the continuation of the communication, and continues the current modulation scheme (π / 4 shift QPSK) regardless of the state of the transmission path until the communication is disconnected. The setting is made (S709).

  In the present embodiment, as an example of requesting the base station apparatus to transmit data at the determined transmission rate, the radio connection control unit of the terminal apparatus 100 performs a modulation scheme currently used for communication and a predetermined modulation. When the method is the same, the base station device 200 is prohibited from switching the modulation method by transmitting a “modulation method change prohibition signal” to the base station device 200. However, the present invention is not limited to this. For example, when the message “transmission path quality notification signal” in the case of performing adaptive modulation shown in FIG. 6 is used and communication is continued, a predetermined modulation scheme (for example, π) is always used regardless of the actual transmission path quality. / 4 shift QPSK) may be repeatedly requested. Further, when the base station apparatus 200 uses the “transmission path quality notification signal” message from the terminal apparatus 100 as indispensable information for starting the adaptive modulation process, the adaptive modulation process is not started. The transmission of the “transmission path quality notification signal” message may be stopped.

  FIG. 8 is a sequence diagram in the case where application switching is performed in the middle of communication in the processing of the wireless section related to the reception of electronic mail by the terminal device. The processing shows the connection of the wireless section between the terminal apparatus 100 and the base station apparatus 200 as in FIGS. 6 and 7, but in this sequence, for example, a modulation scheme with a large amount of information has already been performed by another application such as WWW. FIG. 10 is a sequence diagram illustrating a procedure when receiving an e-mail by switching an application while communication is continued while communication is performed at (16QAM).

  Now, in the terminal device 100 in the communication state (S801) by the modulation method of the large amount of information, the TCP connection with the mail server is established by the processing procedure described in FIG. 4 and FIG. After checking the presence / absence, size information is acquired if there is any (S802).

  When the size of the mail to be received is smaller than a predetermined threshold value, the modulation scheme determining unit 106 determines the modulation scheme to be used as a preset modulation scheme (for example, π / 4 shift QPSK), In addition, a comparison with the modulation method currently in communication is performed.

  As a result of this comparison and confirmation, if the modulation scheme currently being communicated is different from the preset modulation scheme (FIG. 8 is premised on the communication using the multi-information modulation scheme, the modulation scheme in communication is determined in advance. The “transmission path quality notification signal” message requesting the base station apparatus 200 to switch the modulation system is transmitted (S803).

  Receiving the “transmission path quality notification signal” message, the base station apparatus 200 confirms whether or not the response is possible, and if possible, returns a “modulation system notification signal” message (S804) that informs the switching of the modulation system.

  Now, when the “modulation method notification signal” message is received by the terminal device 100, the modulation / demodulation unit 104 performs a modulation method switching process with the base station device 200 in the terminal device 100 (S805). The process proceeds to communication (S806) based on the modulation method (π / 4 shift QPSK).

  In addition, when the terminal apparatus 100 confirms the transition to a new modulation scheme, the radio communication control unit 102 requests the base station apparatus 200 to prohibit switching from the current modulation scheme “Modulation scheme change”. A “prohibition signal” message is generated and transmitted via the wireless unit 107 (S807).

  Then, the base station apparatus 200 that has received it monitors the continuation of the communication, and continues the current modulation scheme (π / 4 shift QPSK) regardless of the state of the radio wave propagation path until the communication is disconnected. Set as follows.

  In the present embodiment, as an example of requesting the base station apparatus to transmit data at the determined transmission rate, a “modulation method change prohibition signal” is transmitted to the base station apparatus 200, whereby the modulation by the base station apparatus 200 is performed. Although switching of the method is prohibited, it is not limited to this. The “transmission path quality notification signal” message requesting modulation with π / 4 shift QPSK transmitted in step 803 may be transmitted repeatedly, or the base station apparatus 200 may transmit a “transmission path quality notification signal” from the terminal apparatus 100. "Message is indispensable information for starting the adaptive modulation processing, the transmission of the" transmission path quality notification signal "message may be stopped so that the adaptive modulation processing is not started.

  Further, in this embodiment, the “modulation method change prohibition signal” is set so that the base station apparatus 200 does not switch the modulation method until communication is cut off. When data transmission / reception is continuously performed by another application such as WWW, the “modulation method change prohibition release signal” may be set to cancel the prohibition of the change.

  Now, after confirming the communication by the new modulation method (π / 4 shift QPSK), the terminal device 100 executes the reception operation of the mail selected for reception.

  FIG. 9 is a sequence diagram illustrating a communication start process and a modulation scheme change process when data is transmitted from the terminal device 100.

  The application control unit 101 of the terminal device 100 calculates the size of data to be transmitted prior to the start of communication when an instruction for transmission of an e-mail or file transfer is issued by the user, and the size information is determined as a communication data amount determination unit. It outputs to 103 and instruct | indicates size determination.

  The communication data amount determination unit 103 compares the size with a predetermined threshold value, and outputs the result to the modulation scheme determination unit 106 (S901).

  When the determination result is output to modulation scheme determining section 106, radio communication control section 102 of terminal apparatus 100 sends an “LCH (Link Channel) establishment request” message requesting base station apparatus 200 to allocate a radio channel. Generated and transmitted via the wireless unit 107 (S902).

  The base station apparatus 200 confirms the availability status of the radio channel, and returns an “LCH allocation” message if there is a vacancy (S903).

  The terminal apparatus 100 transmits a synchronization burst on the assigned radio channel (S904), and the base station apparatus 200 also returns a response of the synchronization burst to the terminal apparatus 100 (S905). Establish.

  If synchronization between the terminal apparatus 100 and the base station apparatus 200 is established and information can be exchanged, the terminal apparatus 100 and the base station apparatus 200 exchange information on modulation schemes that can be processed by each other. Function negotiation including processing is executed (S906), and the communication state is reached (S907).

  Note that the modulation scheme used in the first communication state immediately after the function negotiation is that the transmission path environment is unknown, so that all the devices regardless of whether the terminal device 100 and the base station device 200 support the adaptive modulation scheme. A π / 4 shift QPSK provided in common.

  When the size of the mail to be transmitted is smaller than a predetermined threshold, the modulation scheme determining unit 106 determines the modulation scheme to be used as a preset modulation scheme (for example, π / 4 shift QPSK), A “modulation method request signal” message requesting communication using the determined modulation method is transmitted to the base station apparatus 200 (S908).

  When the terminal apparatus 100 receives the “modulation method notification signal” message (S909), the modulation method is switched by the modulation / demodulation unit 104 controlled by the modulation method determination unit 106, and a new modulation method (π After reaching communication (S910) by / 4 shift QPSK), the mail transmission operation is executed.

  Normally, the modulation scheme of the uplink signal (signal from the terminal device 100 to the base station device 200) is determined based on the signal received by the base station device 200 in the base station device 200 based on the quality of the transmission path. The modulation scheme is determined by measurement. In this embodiment, the modulation scheme is determined by giving priority to the request from the terminal device 100. However, the present invention is not limited to this. For example, in a communication system in which uplink and downlink modulation schemes are adaptively modulated with the same modulation scheme, a modulation scheme corresponding to the worse quality of uplink and downlink transmission channel quality is selected. Therefore, by requesting a preset modulation method (for example, π / 4 shift QPSK) in the “modulation method switching prohibition signal” or “transmission path quality notification signal” described in FIG. Even when the uplink transmission channel quality received and measured by the apparatus 200 is good and the modulation scheme (16QAM) with a large amount of information is selected, the modulation scheme used is a preset modulation scheme (for example, π / 4 shift QPSK). Is determined.

  On the other hand, when the size of the mail to be transmitted is larger than a predetermined threshold value, the modulation scheme determination unit 106 activates adaptive modulation processing similar to the processing shown in FIG. Specifically, the modulation scheme determining unit 106 inputs the quality information of the received signal that is continuously monitored by the quality measuring unit 105, and when the quality exceeds a predetermined value (for example, in FIG. 2). In the case where it is determined that “A” or higher is indicated), 16QAM capable of transmitting a larger amount of information is used as the modulation scheme to be used, and conversely, the quality is less than a specified value (for example, “A” illustrated in FIG. 2). Π / 4 shift QPSK with less occurrence of transmission error, respectively, is determined and transmitted to the wireless communication control unit 102 and the modem unit 104.

  Radio communication control section 102 generates a “transmission path quality notification signal” message requesting setting to the determined modulation scheme, and transmits the message to base station apparatus 200 via radio section 107. On the other hand, when receiving the message, the base station apparatus 200 confirms whether or not the response is possible, and returns a “modulation method notification signal” message informing the switching of the modulation method if the response is possible.

  When the terminal apparatus 100 receives the “modulation method notification signal” message returned from the base station apparatus 200, the terminal apparatus 100 switches the modulation system, and after receiving communication using a new modulation system (16QAM), selects reception. Execute the mail receiving operation.

  In the present embodiment, the transmission operation described above is shown as an example of requesting the base station apparatus to transmit data at the determined transmission rate. However, the present invention is not limited to this. If it is determined in advance that the size of data to be transmitted is smaller than the threshold value, the terminal apparatus 100 can also change the function confirmation information indicating the function included in the terminal apparatus 100 and transmit the function confirmation information to the base station apparatus 200. . Specifically, the function confirmation information indicating the functions provided by itself is information exchanged in the function negotiation when the terminal apparatus 100 and the base station apparatus 200 connect the radio line, and information on the functions provided by each other. (For example, the status of adaptation modulation). That is, when adaptive modulation is started after the start of communication, a list of modulation schemes corresponding to each of the terminal device 100 and the base station device 200 is clarified. Therefore, if it is determined that the size of the data to be transmitted is small and it is not desired to switch to a modulation scheme (for example, 16QAM) capable of transmitting a large amount of information, a function check provided in the terminal device 100 is confirmed. Information related to a modulation scheme (for example, 16QAM) capable of transmitting a large amount of information is deleted from the information, and the function confirmation information after the deletion is transmitted as new function confirmation information to the base station apparatus 200 by function negotiation. In this case, even if the quality of the uplink signal is good, the base station apparatus 200 determines that the terminal apparatus 100 is not compatible with a modulation scheme (for example, 16QAM) that allows transmission of a large amount of information, and more transmission errors. A modulation scheme (for example, π / 4 shift QPSK) with less occurrence of is continued until the end of communication.

  The operation of the terminal device 100 configured as above will be described.

  When the terminal device 100 receives an e-mail reception instruction from the user, the wireless communication control unit 102 performs wireless connection with the base station device 200 and then the application control unit 101 establishes a TCP connection to the mail server. Establishing. Then, prior to receiving the e-mail from the mail server, the application control unit 101 acquires the presence / absence of mail addressed to the terminal on the server and, in some cases, information (list, size, sender, etc.) about the mail. Then, the mail to be received is selected and the size information of the data is output to the communication data amount determination unit 103.

  The communication data amount determination unit 103 compares the size information from the application control unit 101 with a predetermined threshold value, and outputs the result to the modulation scheme determination unit 106.

  When the size of data to be received is smaller than the threshold value, modulation scheme determination section 106 determines a predetermined modulation scheme (for example, π / 4 shift QPSK) as the modulation scheme with base station apparatus 200, and performs wireless communication. Output to the control unit 102.

  On the other hand, when the size of the data to be received is larger than the threshold value, a corresponding modulation scheme (for example, 16QAM) is determined based on the quality information from the quality measuring unit 105 and output to the radio communication control unit 102. To do.

  Radio communication control section 102 generates a message requesting base station apparatus 200 for the modulation scheme determined by modulation scheme determination section 106. This message is, for example, a “modulation method switching prohibition signal” requesting prohibition of change from the modulation method currently being communicated, or a “transmission path quality notification signal” requesting setting to the modulation method determined by the terminal device 100 Is.

  The wireless communication control unit 102 transmits the generated message to the base station apparatus 200, and when different from the current modulation system, performs a switching process of the modulation system with the base station apparatus 200 to reach a communication state.

  When the application control unit 101 enters a communication state using a desired modulation method, the application control unit 101 receives a desired mail from the mail server, and performs a communication path disconnection process after the reception is completed.

  On the other hand, when receiving a transmission instruction such as e-mail transmission or file transfer from the user, the application control unit 101 first calculates the size of data to be transmitted prior to the start of communication, and the communication data The amount determination unit 103 performs a comparison determination with a predetermined threshold value, and outputs the result to the modulation scheme determination unit 106.

  When the size of data to be transmitted is confirmed, the radio communication control unit 102 starts connection processing with the base station apparatus 200 via the radio unit 107, performs radio channel allocation, function negotiation, and the like. A communication state is reached. Further, when it is determined in the size determination of the data to be transmitted that the data size is smaller than the threshold value, the radio communication control unit 102 determines the modulation scheme determined in advance for the base station apparatus 200. A “modulation method request signal” message requesting communication in (for example, π / 4 shift QPSK) is transmitted, and a response is received.

  When a communication state based on a desired modulation method is reached, the application control unit 101 sends data to be transmitted to the mail server, and waits for a response from the mail server to disconnect the line.

  According to the present embodiment, when receiving data from a predetermined communication partner, terminal apparatus 100 obtains the size of data to be received prior to data reception, and modulates according to the size. Since the method is determined, when the amount of data is small, a highly reliable modulation method that hardly causes transmission errors is fixedly used, and stable data communication can be realized.

  Further, even when data is transmitted to a predetermined partner, the terminal device 100 calculates the size of data to be transmitted prior to data transmission and determines the modulation method according to the data size. Therefore, the data amount is small. In some cases, a highly reliable modulation scheme that is less likely to cause transmission errors is fixedly used, and stable data communication can be realized.

  In the above, it demonstrated based on embodiment of this invention. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

  In the present embodiment, the modulation schemes supported by the modem unit 104 are 16QAM with a large amount of information and a highly reliable π / 4 shift QPSK for convenience of explanation. However, the present invention is not limited to this, and an arbitrary number of modulation schemes including other modulation schemes (a modulation scheme with a larger amount of information and a higher reliability) may be provided.

  In the present embodiment, the modulation / demodulation unit 104 and the modulation scheme determination unit 106 target different modulation schemes such as π / 4 shift QPSK and 16QAM as processing for adaptively changing the transmission rate. However, the present invention is not limited to this, and for example, the error correction coding rate may be the target of processing, and a combination of the modulation scheme and the error correction coding rate may be the target of processing. According to this modification, the transmission rate can be set in more detail. That is, a plurality of types of transmission rates may be realized.

It is a block diagram which shows the communication system which concerns on this Embodiment. It is a figure which shows the structure of the table in connection with the adaptive modulation of the terminal device of FIG. It is a figure which shows the frame format of FIG. It is a flowchart which shows the email reception procedure of the terminal device of FIG. It is a sequence diagram of the e-mail reception protocol of the terminal device of FIG. FIG. 7 is a sequence diagram in the case where the data size is larger than a threshold value in the processing of the wireless section related to the electronic mail reception of the terminal device in FIG. 1. FIG. 6 is a sequence diagram in the case where the data size is smaller than a threshold value in the processing of the wireless section related to the reception of electronic mail by the terminal device of FIG. 1. It is a sequence diagram in the case of performing application switching in the middle of communication in the process of the radio | wireless area regarding the email reception of the terminal device of FIG. It is a sequence diagram regarding electronic mail transmission of the terminal device of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Communication system 10, 100 Terminal device, 200 Base station apparatus, 300 Network, 101 Application control part, 102 Wireless communication control part, 103 Communication data amount determination part, 104 Modulation / demodulation part, 105 Quality measurement part, 106 Modulation system determination part, 107 Radio section, 108 Terminal antenna, 109 Control section.

Claims (8)

A communication unit that communicates data with the base station device at a variable transmission rate;
A reception data size acquisition unit for obtaining information on the size of data to be received prior to reception of data via the communication unit;
A transmission path quality measuring unit for measuring transmission path quality with the base station device;
In accordance with the measured transmission path quality, a transmission rate deriving unit that derives transmission rate candidates with the base station apparatus,
After determining a predetermined transmission rate with the base station apparatus as a transmission rate to be used in the first communication state, if the size of the data to be received is equal to or greater than a threshold value, the derived transmission rate candidate Is determined as the transmission rate with the base station apparatus when the size of the data to be received is smaller than the threshold value. A decision unit;
A transmission rate requesting unit that requests the base station device to transmit data at the determined transmission rate,
The communication unit performs a switching process with the base station device when switching the transmission rate ,
The terminal device characterized in that the transmission rate candidate derived by the transmission rate deriving unit is a value equal to or higher than the transmission rate to be used in the initial communication state determined by the transmission rate determining unit .   The transmission rate request unit changes the transmission rate to the base station device when the transmission rate determined by the transmission rate determination unit is the same as the transmission rate currently set with the base station device. The terminal device according to claim 1, wherein a request not to perform is made. A communication unit that communicates data with the base station device at a variable transmission rate;
A measurement unit that receives data to be transmitted and measures the size of the data to be transmitted;
A transmission path quality measuring unit for measuring transmission path quality with the base station device;
In accordance with the measured transmission path quality, a transmission rate deriving unit that derives transmission rate candidates with the base station apparatus,
After determining a predetermined transmission rate with the base station device as a transmission rate to be used in the first communication state, if the measured data size is equal to or larger than a threshold value, a candidate for the derived transmission rate is selected. A transmission rate determining unit that determines the transmission rate with the base station apparatus, and determines the transmission rate with the base station apparatus as the transmission rate determined in the first communication state when the measured data size is smaller than the threshold value When,
A transmission rate requesting unit that requests the base station device to transmit data at the determined transmission rate,
The communication unit performs a switching process with the base station device when switching the transmission rate ,
The terminal device characterized in that the transmission rate candidate derived by the transmission rate deriving unit is a value equal to or higher than the transmission rate to be used in the initial communication state determined by the transmission rate determining unit .   The transmission rate request unit changes the transmission rate to the base station device when the transmission rate determined by the transmission rate determination unit is the same as the transmission rate currently set with the base station device. 4. The terminal device according to claim 3, wherein a request for not performing the request is made. Obtaining information on the size of data to be received prior to data reception from a base station device communicating at a variable transmission rate;
Measuring channel quality with the base station device;
Deriving transmission rate candidates with the base station apparatus according to the measured transmission path quality;
Determining a predetermined transmission rate with the base station device as a transmission rate to be used in an initial communication state;
If the size of the data to be received is equal to or greater than the threshold, the derived transmission rate candidate is determined as the transmission rate with the base station apparatus, and if the size of the data to be received is smaller than the threshold, the first communication Determining the transmission rate determined in the state as the transmission rate with the base station device;
Requesting the base station device to transmit data at the determined transmission rate;
A step of performing a switching process with the base station device when switching the transmission rate ,
The transmission rate determination method characterized in that the transmission rate candidate derived in the deriving step is a value equal to or higher than the transmission rate to be used in the initial communication state determined in the step of determining the transmission rate. Measuring the size to be transmitted to a base station apparatus communicating at a variable transmission speed prior to data transmission;
Measuring channel quality with the base station device;
Deriving transmission rate candidates with the base station apparatus according to the measured transmission path quality;
Determining a predetermined transmission rate with the base station device as a transmission rate to be used in an initial communication state;
If the measured data size is greater than or equal to the threshold, the derived transmission rate candidate is determined to be the transmission rate with the base station apparatus, and if the measured data size is smaller than the threshold, the first communication state Determining a determined transmission rate as a transmission rate with the base station device;
Requesting the base station device to transmit data at the determined transmission rate;
A step of performing a switching process with the base station device when switching the transmission rate ,
The transmission rate determination method characterized in that the transmission rate candidate derived in the deriving step is a value equal to or higher than the transmission rate to be used in the initial communication state determined in the step of determining the transmission rate. Obtaining information about the size of data to be received from the base station apparatus communicating at a variable transmission rate via the wireless network prior to data reception, and storing the information in a memory;
Measuring channel quality with the base station device;
Deriving transmission rate candidates with the base station apparatus according to the measured transmission path quality;
Determining a predetermined transmission rate with the base station device as a transmission rate to be used in an initial communication state;
If the size stored in the memory is greater than or equal to the threshold, the derived transmission rate candidate is determined as the transmission rate with the base station apparatus, and if the size stored in the memory is smaller than the threshold, the first communication Determining the transmission rate determined in the state as the transmission rate with the base station device;
Requesting transmission of data at the determined transmission rate to a base station device via the wireless network;
A step of performing a switching process with the base station device when switching the transmission rate ,
A program for causing a computer to execute that a transmission rate candidate derived in the deriving step is a value equal to or higher than a transmission rate to be used in an initial communication state determined in the step of determining the transmission rate . Measuring the size of data to be transmitted to a base station apparatus communicating at a variable transmission rate, prior to data transmission via an interface with the program that generated the data to be transmitted, and storing the data in a memory; ,
Measuring channel quality with the base station device;
Deriving transmission rate candidates with the base station apparatus according to the measured transmission path quality;
Determining a predetermined transmission rate with the base station device as a transmission rate to be used in an initial communication state;
If the size stored in the memory is greater than or equal to the threshold, the derived transmission rate candidate is determined as the transmission rate with the base station apparatus, and if the size stored in the memory is smaller than the threshold, the first communication Determining the transmission rate determined in the state as the transmission rate with the base station device;
Requesting transmission of data at the determined transmission rate to a base station device via the wireless network;
A step of performing a switching process with the base station device when switching the transmission rate ,
A program for causing a computer to execute that a transmission rate candidate derived in the deriving step is a value equal to or higher than a transmission rate to be used in an initial communication state determined in the step of determining the transmission rate .

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