JP5053111B2 - Wireless communication method and mobile communication terminal - Google Patents

Description

  The present invention relates to a radio communication method and a mobile communication terminal capable of radio communication using an adaptive modulation scheme.

  In mobile communication terminals including PHS (Personal Handy phone System) terminals, in addition to transmission / reception of data signals by packet communication, PIAFS (Personal handy phone system Internet Access Forum Standard) that transmits / receives data signals using voice communication paths. ) Can be used.

  The PIAFS is a PHS data communication standard established by PIAF (Personal handy phone system Internet Access Forum), and is 32 kbit / s unrestricted digital bearer or 64 kbit / s through an ISDN (Integrated Services Digital Network) network. This is a transmission procedure capable of transmitting high-quality data using an unrestricted digital bearer.

The modulation method between the mobile communication terminal and the base station when transmitting and receiving data signals by PIAFS is limited to QPSK (Quadrature Phase Shift Keying). Conventionally, when a mobile communication terminal establishes a link channel with a base station, QPSK is first selected as a modulation method, so that even if the communication is PIAFS, a smooth connection can be established.
ARIB (Association of Radio Industries and Businesses) STD-T76 ARIB STD-28

  In recent years, there has been a demand for improvements in communication quality and communication speed as well as downsizing and weight reduction of mobile communication terminals. For example, adaptive modulation schemes that adaptively change modulation schemes according to changes in the communication environment and improve communication speed while maintaining communication quality are being adopted.

  Such an adaptive modulation scheme is based on the signal-to-interference and noise ratio (SINR) and bit error rate of an uplink communication signal transmitted from a mobile communication terminal to a base station. Estimate the communication environment between them, select a modulation method with a higher communication rate in a better communication environment, and select a modulation method with a lower communication rate in a worse communication environment, and stable wireless communication It is a method to implement.

  In a base station using such an adaptive modulation scheme, BPSK (Binary Phase Shift Keying) different from QPSK may be selected as a modulation scheme for establishing communication according to the radio wave environment with the mobile communication terminal.

  FIG. 8 is a sequence diagram showing a processing procedure in the case where a conventional incoming call is PIAFS. When there is an incoming call to the mobile communication terminal 10, the base station 20 informs the mobile communication terminal 10 that the incoming call has been received (S30), and since the mobile communication terminal 10 receives the incoming call, the base station 20 A link channel establishment request is sent to 20 (S32). The base station 20 determines a modulation scheme, assigns a communicable link channel (S34), and transmits the modulation scheme and link channel to the mobile communication terminal 10 (S36). The mobile communication terminal 10 performs frame synchronization (synchronization burst) on the link channel based on the transmitted modulation scheme and link channel (S38), and sends an incoming call response to the base station 20 after the synchronization is completed. (S40).

  In response to the incoming call response, the base station 20 transmits call setting information including the signal type to be communicated to the mobile communication terminal 10 (S42), and the mobile communication terminal 10 sets the call based on the call setting information. (S44). Here, when the incoming call is PIAFS and the selected modulation method is BPSK, PIAFS which is assumed only for communication by QPSK cannot establish wireless communication by BPSK, and the mobile communication terminal 10 It had to be cut (S46).

  In order to avoid such a situation, the mobile communication terminal 10 is provided with a command to turn off the adaptive modulation scheme when establishing a link channel. However, if the adaptive modulation scheme is turned off at the stage (S32) where the incoming call does not know what signal type, wireless communication at a high communication rate expected by the appropriate modulation scheme is suppressed, This leads to a problem that resources cannot be used effectively.

  In view of such a problem, the present invention provides a wireless communication system that can continue wireless communication without disconnecting an incoming call even if an incoming call is received by PIAFS from a base station using an adaptive modulation scheme. An object is to provide a communication method and a mobile communication terminal.

  In order to solve the above problems, a typical configuration of the present invention is a wireless communication method in which a base station and a mobile communication terminal perform wireless communication using an adaptive modulation scheme, and the base station receives an incoming call to the mobile communication terminal. In response to the incoming call, the mobile communication terminal requests establishment of wireless communication with the base station, the base station determines the modulation method based on the adaptive modulation method, and moves the modulation method. The mobile communication terminal transmits an incoming call response to the modulation scheme, the base station transmits call setting information including at least the signal type to the mobile communication terminal, and the mobile communication terminal transmits the transmitted signal. It is determined whether the type is a data signal and whether the modulation method is QPSK. If the signal type is a data signal and the modulation method is other than QPSK, the modulation method is fixed to QPSK. Request for establishment of wireless communication including the request Characterized by degrees executed. Such a data signal may be a data signal based on PIAFS. Here, the signal type represents identification of the data signal and the audio signal.

  When BPSK is selected as the modulation method for establishing communication even though the incoming call is a communication connection request by PIAFS, the conventional mobile communication terminal performs wireless communication when it recognizes the PIAFS communication incoming call information. Disconnected (released). In the present invention, it is possible to wait for the activation of PIAFS, reestablish wireless communication by QPSK after connecting with BPSK, and switch the modulation method from BPSK to QPSK without disconnecting the communication connection. Therefore, stable communication connection by PIAFS can be executed regardless of the selection of the modulation scheme of the base station.

  The mobile communication terminal and the base station are connected by time division multiple access, the establishment request for wireless communication is a link channel establishment request, and the fixed request to the modulation scheme QPSK functions adaptive modulation in the link channel establishment request It may be executed by a command that is not allowed.

  In a mobile communication terminal, an on / off command for adaptive modulation is provided in a link channel establishment request when making a wireless communication establishment request. Since PIAFS uses voice communication, QPSK is inevitably selected as the modulation method when adaptive modulation is turned off. As described above, since the fixed request to QPSK is executed using the existing information transmission means, it is possible to cope with only the software update without adding hardware, and the present invention is also applied to the existing mobile communication terminal. It becomes possible.

  Another configuration according to the present invention is a mobile communication terminal that performs radio communication with a base station using an adaptive modulation method, and that establishes a radio communication establishment request with the base station in response to an incoming call from the base station An incoming call response unit that receives an incoming call response to the modulation scheme determined by the base station, a call setting information reception unit that receives call setting information including at least a signal type from the base station, and a signal type that is a data signal A call setting information determining unit that determines whether or not the modulation method is QPSK, and when the signal type is a data signal and the modulation method is other than QPSK, A modulation scheme changing unit that causes the establishment requesting unit to again execute a wireless communication establishment request including a fixed request.

  The components corresponding to the technical idea in the wireless communication method described above and the description thereof can be applied to the mobile communication terminal.

  As described above, according to the present invention, even when an incoming call by PIAFS is received from a base station using the adaptive modulation scheme, wireless communication can be continued without disconnecting the incoming call.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  A mobile communication terminal represented by a PHS terminal, a mobile phone, or the like constructs a wireless communication system that performs wireless communication with a base station that is fixedly arranged at a predetermined interval. Here, in order to facilitate understanding, the entire wireless communication system will be described, and then specific configurations of a PHS terminal and a base station as mobile communication terminals will be described. In this embodiment, a PHS terminal is cited as a mobile communication terminal. However, the present invention is not limited to such a case. A mobile phone, a notebook personal computer, a PDA (Personal Digital Assistant), a digital camera, a music player, car navigation, portable Various electronic devices capable of wireless communication, such as televisions, game devices, DVD players, and remote controllers can also be used as mobile communication terminals.

(Wireless communication system 100)
FIG. 1 is an explanatory diagram showing a schematic connection relationship of the wireless communication system 100. The wireless communication system 100 includes a PHS terminal 110 (110A, 110B), a base station 120 (120A, 120B), an ISDN (Integrated Services Digital Network) line, an Internet, a dedicated line, etc. And a relay server 140.

  In the wireless communication system 100, when a user connects a communication line from his / her PHS terminal 110A to another PHS terminal 110B, the PHS terminal 110A makes a wireless connection request to the base station 120A within the communicable range. . The base station 120A that has received the wireless connection request requests the relay server 140 to establish a communication connection with the communication partner via the communication network 130, and the relay server 140 is within the wireless communication range of the other PHS terminal 110B, for example, Station 120B is selected to secure a communication path between base station 120A and base station 120B, and communication between PHS terminal 110A and PHS terminal 110B is established. Here, data transmission by PIAFS is performed using such a communication line, particularly a voice communication line.

  In such a wireless communication system 100, an adaptive modulation scheme that adaptively changes the modulation scheme according to changes in the communication environment and improves the communication speed while maintaining the communication quality between the PHS terminal 110 and the base station 120 is used. Can do. However, in PIAFS, since only QPSK communication is assumed, wireless communication by BPSK cannot be established, and even if an incoming call is received, the call is forcibly disconnected. In this embodiment, even if an incoming call by PIAFS is received from a base station using the adaptive modulation method, wireless communication by PIAFS can be continued without disconnecting the incoming call.

(PHS terminal 110)
FIG. 2 is a functional block diagram showing a hardware configuration of the PHS terminal 110, and FIG. 3 is a perspective view showing an appearance of the PHS terminal 110. As shown in FIG. The PHS terminal 110 includes a terminal control unit 210, a terminal memory 212, a display unit 214, an operation unit 216, a voice input unit 218, a voice output unit 220, and a terminal wireless communication unit 222. .

  The terminal control unit 210 manages and controls the entire PHS terminal 110 using a semiconductor integrated circuit including a central processing unit (CPU). In addition, the terminal control unit 210 performs a call function, a mail transmission / reception function, an imaging function, a music playback function, and a TV viewing function using the program in the terminal memory 212.

  The terminal memory 212 includes a ROM, a RAM, an EEPROM, a non-volatile RAM, a flash memory, an HDD (Hard Disk Drive), and the like, and stores a program processed by the terminal control unit 210, audio data, and the like.

  The display unit 214 includes a liquid crystal display, EL (Electro Luminescence), etc., and is stored in the terminal memory 212 or provided from an application relay server (not shown) via the communication network 130, An application GUI (Graphical User Interface) can be displayed.

  The operation unit 216 includes switches such as a keyboard, a cross key, and a joystick, and receives a user operation input.

  The voice input unit 218 includes voice recognition means such as a microphone, and converts the user's voice input during a call into an electrical signal that can be processed in the PHS terminal 110.

  The voice output unit 220 includes a speaker, and converts the voice signal of the call partner received by the PHS terminal 110 into voice and outputs the voice. Further, a ring tone, an operation sound of the operation unit 216, an alarm sound, etc. can be output.

  The terminal wireless communication unit 222 performs wireless communication with the base station 120 in the communication network 130. As such wireless communication, time division multiple access (TDMA) that performs communication by allocating a plurality of time slots obtained by time-dividing frames in the base station 120 to the channels of the PHS terminal 110 is adopted. Has been.

  In the present embodiment, the terminal control unit 210 also functions as an establishment request unit 230, an incoming call response unit 232, a call setting information reception unit 234, a call setting information determination unit 236, and a modulation scheme change unit 238.

  In response to an incoming call from the base station 120, the establishment request unit 230 requests establishment of wireless communication with the base station 120 via the terminal wireless communication unit 222, particularly a time-division link channel in time division multiple access. A link channel establishment request for assignment is made.

  The incoming call response unit 232 receives the link channel assigned by the base station and the modulation scheme determined based on the adaptive modulation scheme, performs frame synchronization (synchronization burst) on the link channel, and completes synchronization. Thereafter, an incoming call response is made to the base station 120.

  The call setting information receiving unit 234 receives the call setting information generated at the base station 120 in response to the incoming call response and includes at least the signal type, and performs call setting.

  The call setting information determination unit 236 determines whether the signal type in the call setting information received by the call setting information receiving unit 234 is a data signal and whether the modulation scheme received by the incoming call response unit 232 is QPSK. Determine whether.

  When the call setting information determination unit 236 determines that the signal type is a data signal and the modulation method is other than QPSK, the modulation method change unit 238 forcibly changes the modulation method to QPSK. The establishment request unit 230 is made to execute the link channel establishment request including the fixed request to the system QPSK again.

(Base station 120)
FIG. 4 is a block diagram illustrating a schematic configuration of the base station 120. The base station 120 includes a base station control unit 310, a base station memory 312, a base station wireless communication unit 314, and a base station wired communication unit 316.

  The base station control unit 310 manages and controls the entire base station 120 using a semiconductor integrated circuit including a central processing unit (CPU). Further, the base station control unit 310 controls communication connection of the PHS terminal 110 to the communication network 130 and other PHS terminals 110 using a program in the base station memory 312.

  The base station memory 312 includes ROM, RAM, EEPROM, nonvolatile RAM, flash memory, HDD, and the like, and stores programs processed by the base station control unit 310, time information, and the like.

  The base station wireless communication unit 314 can establish communication with the PHS terminal 110 and adaptively change the modulation scheme and codec according to the communication quality of the PHS terminal 110.

  The base station wired communication unit 316 can be connected to various servers including the relay server 140 via the communication network 130.

  In the present embodiment, the base station control unit 310 also functions as an incoming call transmission unit 330, a channel allocation unit 332, a call setting transmission unit 334, and a communication start unit 336.

  When there is an incoming call to the PHS terminal 110 registered in the location registration area including the base station 120, the incoming call transmission unit 330 makes a simultaneous call to the location registration area and receives the incoming call to the PHS terminal 110. Communicate that there was.

  When there is a request for establishing a link channel for wireless communication with itself from the PHS terminal 110 that has transmitted the incoming call, the channel allocation unit 332 is based on the signal-to-interference noise ratio of the communication signal from the PHS terminal 110 and the bit error rate. Then, a modulation scheme with the PHS terminal 110 is determined, a communicable link channel is allocated, and the modulation scheme and link channel are transmitted to the PHS terminal 110.

  When the PHS terminal 110 establishes synchronization with the link channel and returns an incoming call response, the call setting transmission unit 334 transmits call setting information including at least a signal type to the PHS terminal 110.

  When the communication start unit 336 recognizes that the call setting of the PHS terminal 110 that has transmitted the call setting information is completed, the communication start unit 336 starts communication with the PHS terminal 110 using the allocated link channel.

  The PHS terminal 110 and the base station 120 described above can perform a stable communication connection by PIAFS regardless of the modulation scheme selected by the base station 120. Hereinafter, a schematic wireless communication method when the PHS terminal 110 receives an incoming call will be described with reference to a flowchart, and a detailed processing procedure when the communication is PIAFS will be described with reference to a sequence diagram. .

(Wireless communication method)
FIG. 5 is a flowchart showing a schematic processing flow of the wireless communication method. First, when an incoming call occurs in the PHS terminal 110, the base station 120 notifies the PHS terminal 110 to that effect (S400), and the PHS terminal 110 requests the base station 120 to establish a link channel (S402). The link channel establishment request at this time includes a command for making adaptive modulation function (adaptive modulation ON).

  FIG. 6 is an explanatory diagram showing a message format (SCCH: Signaling Control CHannel) of a link channel establishment request. The link channel establishment request has a data length of 8 bits × 5 octets. Then, the link channel (LCH) type is specified by a 3-bit length of 6 to 8 bits of 2 octets of the link channel establishment request shown in FIG. In this embodiment, when “100” is set in such a bit string, adaptive modulation is turned on, and any modulation scheme of π / 4 shift QPSK 32 kbit / s or 16 kbit / s or π / 2 shift BPSK 16 kbit / s is allowed. When “000” is set in the bit string, adaptive modulation is turned off, and the modulation method can be fixed to π / 4 shift QPSK 32 kbit / s.

  The base station 120 determines a modulation scheme and allocates a link channel in response to an adaptive modulation ON command (S404). Then, call setting including setting of the signal type of the signal to be connected is executed (S406). Here, the PHS terminal 110 determines whether or not the signal type is a data signal (S408), and if it is not a data signal, that is, if it is a voice signal, it starts voice communication (S410).

  If the data signal is determined to be a data signal in the data signal determination step (S408), it is further determined whether the modulation method transmitted from the base station 120 is QPSK (S412). If QPSK, communication by PIAFS is started. (S414). Here, when it is determined that it is not QPSK, that is, it is BPSK, communication by BPSK is temporarily connected and a link channel establishment request is executed again (S416). At this time, unlike immediately after the incoming call, the setting is switched to a command (adaptive modulation off) that does not function adaptive modulation, and a link channel establishment request is made.

  The base station 120 turns off adaptive modulation, that is, selects QPSK as the modulation scheme and assigns a link channel again (S418). Then, call setting including setting of the signal type of the signal to be connected is executed (S420), and communication by PIAFS is started (S414), similarly to the case where QPSK is determined in the QPSK determination step (S412).

  FIG. 7 is a sequence diagram showing a detailed processing procedure when the incoming call is PIAFS. When there is an incoming call to the PHS terminal 110 registered in the location registration area including the base station 120, the base station 120 makes a simultaneous call to the location registration area and the PHS terminal 110 has an incoming call. (S500), the PHS terminal 110 makes a link channel establishment request to the base station 120 with adaptive modulation ON in order to receive the incoming call (S502).

  The base station 120 determines a modulation scheme based on the signal-to-interference noise ratio and bit error rate of the communication signal from the PHS terminal 110 in response to adaptive modulation being turned on, and allocates a communicable link channel (S504). Then, the modulation scheme and the link channel are transmitted to the PHS terminal 110 (S506). The PHS terminal 110 performs frame synchronization (synchronization burst) on the link channel based on the transmitted modulation scheme and link channel (S508), and after the synchronization is completed, makes an incoming call response to the base station 120 ( S510).

  In response to the incoming call response, the base station 120 transmits call setting information including a signal type to be communicated to the PHS terminal 110 (S512), and the PHS terminal 110 performs call setting based on the call setting information. (S514), the base station 120 is notified that the call setting has been accepted (S516). Thus, communication is started between the PHS terminal 110 and the base station 120 (S518). However, if the signal type is a data signal and the modulation method is BPSK, the PHS terminal 110 does not activate PIAFS and prepares for re-establishment of the link channel by QPSK (S520).

  In order to fix the modulation scheme to QPSK, the PHS terminal 110 makes a link channel establishment request to the base station 120 again with adaptive modulation off (S522). Since PIAFS uses voice communication, QPSK is inevitably selected as the modulation method when adaptive modulation is turned off. As described above, since the fixed request to QPSK is executed using the existing information transmission means (adaptive modulation on / off), it is possible to cope with only the software update without adding hardware, and the existing PHS terminal. This embodiment can also be applied to 110.

  In response to the link channel establishment request again from the PHS terminal 110, the base station 120 fixes the modulation scheme to QPSK and assigns a communicable link channel again (S524). Then, the modulation scheme (QPSK) and the link channel are transmitted to the PHS terminal 110 (S526). The PHS terminal 110 performs frame synchronization (synchronization burst) on the link channel (S528), and after the synchronization is completed, makes a call response to the base station 120 (S530).

  In response to the incoming call response, the base station 120 transmits call setting information including a signal type to be communicated to the PHS terminal 110 (S532), and the PHS terminal 110 performs call setting based on the call setting information ( In step S534, the base station 120 is notified that the call setting has been accepted (S536). Finally, communication by PIAFS is started between the PHS terminal 110 and the base station 120 (S538).

  In the wireless communication method of the present embodiment, as described above, the PIAFS activation is waited, and once the connection is established by BPSK, the wireless communication is re-established by QPSK. It is possible to switch from BPSK to QPSK. Therefore, it is possible to execute a stable communication connection by PIAFS regardless of the modulation scheme of the base station 120 selected.

  The sequence similar to that of the above-mentioned incoming call is also performed at the time of so-called handover in which the communication target is switched to another base station 120 having a good communication environment while the PHS terminal 110 has established communication with the specific base station 120. The link channel establishment operation is executed by. Therefore, by executing the reestablishment of the link channel in the present embodiment using the existing handover sequence, a significant software change can be avoided, and the cost can be reduced.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  Note that the steps in the wireless communication method of the present specification do not necessarily have to be processed in chronological order according to the order described in the flowchart, but are executed in parallel or individually (for example, parallel processing or object-based processing). Processing).

  INDUSTRIAL APPLICABILITY The present invention can be used for a radio communication method and a mobile communication terminal capable of radio communication using an adaptive modulation scheme.

It is explanatory drawing which showed the rough connection relation of the radio | wireless communications system in this embodiment. It is the functional block diagram which showed the hardware constitutions of the PHS terminal. It is the perspective view which showed the external appearance of the PHS terminal. It is the block diagram which showed the schematic structure of the base station. It is the flowchart which showed the flow of the rough process of the radio | wireless communication method. It is explanatory drawing which showed the message format of a link channel establishment request | requirement. It is the sequence diagram which showed the detailed process sequence in case an incoming call is PIAFS. It is the sequence diagram which showed the process sequence in the case of a conventional incoming call being PIAFS.

Explanation of symbols

110 PHS terminal (mobile communication terminal)
120 ... base station 230 ... establishment request unit 232 ... incoming call response unit 234 ... call setting information receiving unit 236 ... call setting information determining unit 238 ... modulation method changing unit

Claims (4)

A wireless communication method in which a base station and a mobile communication terminal perform wireless communication using an adaptive modulation method,
The base station communicates that there is an incoming call to the mobile communication terminal,
The mobile communication terminal requests establishment of wireless communication with a base station in response to the incoming call,
The base station determines a modulation scheme based on an adaptive modulation scheme, and transmits the modulation scheme to the mobile communication terminal;
The mobile communication terminal receives an incoming call response to the modulation scheme,
The base station transmits call setting information including at least a signal type to the mobile communication terminal,
The mobile communication terminal determines whether the transmitted signal type is a data signal and whether the modulation scheme is QPSK;
When the signal type is a data signal and the modulation method is other than QPSK, a wireless communication establishment request including a request for fixing the modulation method to QPSK is executed again. The mobile communication terminal and the base station are connected by time division multiple access,
The wireless communication establishment request is a link channel establishment request,
2. The wireless communication method according to claim 1, wherein the request for fixing the modulation scheme to QPSK is executed by a command that does not function adaptive modulation in the link channel establishment request.   The wireless communication method according to claim 1, wherein the data signal is a data signal based on PIAFS. A mobile communication terminal for performing wireless communication with a base station using an adaptive modulation method,
An establishment request unit for making a request for establishment of wireless communication with the base station in response to an incoming call from the base station;
An incoming call response unit for making an incoming call response to the modulation scheme determined by the base station;
A call setting information receiving unit for receiving call setting information including at least a signal type from the base station;
A call setting information determination unit for determining whether the signal type is a data signal and whether the modulation method is QPSK;
A modulation scheme changing unit that, when the signal type is a data signal and the modulation scheme is other than QPSK, causes the establishment requesting unit to re-execute a wireless communication establishment request including a request for fixing the modulation scheme to QPSK; ,
A mobile communication terminal comprising:

Images