JP2011199848A - Portable radio communication terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a portable radio communication terminal capable of preventing the deterioration of voice quality when an incoming request of voice communication is generated during packet communication using a plurality of time slots.SOLUTION: The portable radio communication terminal includes: a communication control part 150 which performs voice communication and packet communication in a TDMA-TDD system through a base station; a slot allocation part 122 which allocates communication to the time slots consisting of a pair of reception transmission slots; a communication quality acquisition part 160 which acquires the communication quality of each reception slot; and a storage part 152 which stores communication quality by making it associated with a plurality of reception slots. The slot allocation part allocates time slots containing a reception slot having the best communication quality among the plurality of time slots to voice communication based on data in the storage part when an incoming request of voice communication is generated during packet communication using a plurality of time slots.

Description

  The present invention relates to a portable radio communication terminal capable of performing voice communication and packet communication by a TDMA-TDD system.

In recent years, wireless communication terminals represented by PHS (Personal Handy phone System) and mobile phones have become widespread, and it has become possible to make calls and obtain information regardless of location or time. Such a wireless communication terminal is connected to a communication network by performing wireless communication with a base station installed at a predetermined location.

  In wireless communication using PHS or the like, for example, TDMA-TDD (TDMA: Time Division Multiple Access: TDD: Time Division Duplex) is used.

  The TDD scheme is a scheme in which, for example, a radio communication terminal (PS: Personal Station) and a base station (CS: Cell Station) switch communication timings from one to the other and from the other to the other alternately and in a short time. In wireless communication using the TDD scheme, a communication terminal receives data at a timing when the base station transmits, and conversely, a base station receives data at a timing when the communication terminal transmits. Such switching control is executed via an RF (Radio Frequency) circuit. The RF circuit is a circuit that can transmit and receive high-frequency radio waves, and includes a transmission circuit and a reception circuit that can operate independently.

  The TDMA method is a method of subdividing into a plurality of time slots on the time axis and performing communication in parallel with a plurality of opponents through the subdivided time slots. A time slot is composed of a pair of a reception slot and a transmission slot. Specifically, each of the transmission slot and the reception slot is time-divided into four, and communication can be performed in four time slots. The four time slots are used as the first control channel and the second to fourth communication channels. However, since the control signal is sent intermittently, the first time slot is also used when the control signal is not transmitted or received. Used as a communication channel.

  Here, TDMA was originally devised to communicate with a plurality of communication terminals. However, when one communication terminal performs communication using a plurality of time slots, packet communication can be accelerated or voice communication can be performed. It has been done to stabilize. Therefore, for example, a communication terminal can communicate with a plurality of base stations using different channels, and can communicate with a single base station using different channels.

  When assigning a channel for communication connection between a communication terminal and a base station, a connection request message is first transmitted from the communication terminal to the base station. The base station selects a time slot and a carrier (carrier wave) with the least interference wave through carrier sense in an available time slot, and transmits the combination (channel) of the time slot and carrier in an allocation message. The communication terminal confirms whether or not the allocated channel is usable through carrier sense of the channel, and then starts connection.

  It has also been proposed and implemented to simultaneously perform voice communication and packet communication. In Patent Document 1, the generated circuit-switched calls (voice communication incoming calls) are sequentially assigned to empty slots, and the generated packet-switched calls (packet communication outgoing calls) are not used as control channels in the control slot empty. It has been proposed to assign to slots. According to Patent Document 1, it is possible to efficiently mix rotation-switched communication and packet-switched communication.

JP-A-9-55768

  By the way, in recent years, in order to perform comfortable communication as fast as possible in packet communication, communication is performed using all (for example, four) time slots as much as possible. Heretofore, when voice communication is received during packet communication using all time slots, packet communication is stopped at one of the time slots, and voice communication is assigned to this. Has been done. Further, even when not using all the time slots, if the unused time slot is occupied by another communication terminal, the packet is still used in one of the plurality of used time slots. Communication is stopped and voice communication is assigned.

  At present, the time slot assigned to voice communication after stopping packet communication is a procedure (protocol) designated by the base station. Although it is certain that communication is possible because it is a time slot in which packet communication was performed, since voice communication requires real-time performance compared to packet communication, higher communication quality is required. However, the time slot allocated at this time does not necessarily have a high channel quality, and in some cases, the voice quality is low, so that the time slot may be interrupted or a handover may be required.

  Accordingly, the present invention provides a portable wireless terminal capable of preventing deterioration of voice quality even when an incoming request for voice communication is generated when packet communication is performed using a plurality of time slots. It is aimed.

  In order to solve the above problems, a typical configuration of a portable radio communication terminal according to the present invention includes a communication control unit that performs voice communication and packet communication using a TDMA-TDD scheme via a base station, a reception slot, and a transmission slot. A slot allocating unit for allocating communication to a pair of time slots, a communication quality acquiring unit for acquiring the communication quality of each reception slot for a plurality of time slots allocated to packet communication, and a plurality of reception slots And a storage unit that stores the data in association with each other, and the slot allocation unit includes a plurality of slot allocation units based on the data stored in the storage unit when an incoming request for voice communication occurs when packet communication is performed using a plurality of time slots. Of these time slots, the time slot including the reception slot with the best communication quality is assigned to voice communication. To.

  According to the above configuration, voice communication can be started without degrading voice quality even when packet communication is performed using a plurality of time slots. In particular, by storing the communication quality in the storage unit, it is possible to evaluate the communication quality in a certain time width instead of the instantaneous value, and accordingly, it is possible to appropriately assign a time slot having a high communication quality to the voice communication. In addition, it is only necessary to modify the control program, and the hardware is not changed. Therefore, the control program can be realized at a relatively low cost, and the present invention can be implemented in an existing communication terminal. .

  The communication control unit can control slot diversity in which voice communication is performed using two time slots, and the slot allocation unit receives a communication with a better communication quality among a plurality of time slots based on data in the storage unit. Two time slots including slots may be allocated for voice communication. Thereby, also when performing slot diversity, the quality of voice communication can be improved similarly.

When the slot allocating unit determines that the communication quality of the time slot allocated to the voice communication has deteriorated, the other slot is set to the voice communication according to the communication quality acquired by the communication quality acquiring unit. It may be assigned.

  As a result, the connection of the packet communication path that has not been selected for voice communication after switching to voice communication is continued, and the communication quality is acquired, so that even when the selected communication path deteriorates, it is newly added. It is possible to change the communication path without performing a search or the like.

  In addition, another typical configuration of the portable radio communication terminal according to the present invention includes a communication control unit that performs voice communication and packet communication by a TDMA-TDD system via a base station, and a pair of a reception slot and a transmission slot. A slot allocation unit that allocates communication to time slots, and an adaptive modulation / demodulation unit that can transmit and receive a plurality of time slots allocated to packet communication using different modulation schemes. The slot allocation unit uses a plurality of time slots. When a voice communication incoming request is generated during packet communication, a time slot including a transmission slot communicated with the modulation method having the highest transfer rate is assigned to the voice communication among a plurality of time slots. It is characterized by that.

  Even with the above configuration, voice communication can be started without deteriorating voice quality even when packet communication is performed using a plurality of time slots. In particular, in packet communication, the communication quality is dynamically switched to a modulation method with a higher transfer rate as the communication quality is higher, so that the communication quality can be evaluated by the modulation method. Therefore, it is possible to appropriately allocate time slots with high communication quality to voice communication.

  The communication control unit can control slot diversity for performing voice communication using two time slots, and the slot allocation unit communicates with a modulation method having a higher transfer rate among a plurality of time slots. Two time slots including a transmission slot may be allocated for voice communication.

  The slot assigning unit may assign the time slot used for the voice communication to the packet communication after the voice communication is finished. Thereby, also when performing slot diversity, the quality of voice communication can be improved similarly.

  A movement speed detection unit that detects the movement speed of the terminal may further be provided, and the communication control unit may maintain voice communication and stop packet communication when the movement speed exceeds a predetermined value. When the communication terminal is moving at high speed, the number of handovers increases, and an attempt is made to maintain the connection by antenna diversity or slot diversity. In such a case, if communication is attempted from all the time slots, there is a possibility that the connection of other communication terminals may be restricted around the passing base station. Therefore, by controlling so as to maintain only voice communication as described above, voice communication can be stabilized and the influence on other communication terminals can be reduced.

  According to the present invention, voice communication can be started without degrading voice quality even when packet communication is performed using a plurality of time slots. Further, it is only necessary to modify the control program, and the hardware is not changed. Therefore, the control program can be realized at a relatively low cost, and the present invention can be implemented in an existing communication terminal.

It is a figure explaining the schematic structure of the portable radio | wireless communication terminal concerning 1st Embodiment. It is a flowchart explaining the operation example of 1st Embodiment. It is a figure explaining a time slot. It is a flowchart explaining the other operation example of 2nd Embodiment. It is a figure explaining schematic structure of the portable radio | wireless communication terminal concerning 3rd Embodiment.

  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.

[First Embodiment]
FIG. 1 is a diagram illustrating a schematic configuration of a portable wireless communication terminal (hereinafter referred to as “communication terminal 100”). In the present embodiment, the communication terminal 100 that performs voice communication and packet communication using the TDMA-TDD method will be described using a PHS as an example. However, the present invention is not limited to the PHS, but includes a TDMA-TDD system such as a mobile phone, a notebook personal computer, a PDA (Personal Digital Assistant), a digital camera, a music player, a car navigation system, a portable TV, a game device, a DVD player, and a remote controller. The present invention can be applied to any device that communicates with the network.

  The audio conversion unit 110 encodes an audio signal (analog signal) input from the microphone 112 using, for example, ADPCM (Adaptive Differential Pulse Code Modulation) and converts the signal into a digital signal. Further, the digital signal is converted into an audio signal and output from the speaker 114.

  The channel codec unit 120 includes a slot allocation unit 122 and a codec unit 124. The slot allocation unit 122 allocates communication to a time slot that is a pair of a reception slot and a transmission slot. The codec unit 124 performs framing (dividing and assigning) the audio data and the control signal for each time slot, and deframing (combining and restoring the digital signal). The procedure with the base station for assigning the time slot from the standby state (the state in which communication is not performed) is the same as in the above-described conventional technology.

The adaptive modulation / demodulation unit 130 modulates the digital signal framed by the codec unit 124 to generate a baseband signal, or demodulates the digital signal from the baseband signal. Data signal modulation methods include BPSK (Binary Phase Shift Keying), Q
There are PSK (quadrature phase shift keying), 16QAM (Quadrature Amplitude Modulation), 64QAM, and the like. Further, an error correction technique such as FEC (Forward Error Correction) is also used.

  The RF circuit 140 up-converts the baseband signal (modulation data) to a predetermined frequency and transmits a radio signal from the antenna 142. Further, the radio signal received by the antenna 142 is down-converted into a baseband signal.

  The communication control unit 150 controls the channel codec unit 120, the adaptive modulation / demodulation unit 130, and other units, and communicates with a base station (not shown). Specifically, the communication control unit 150 is realized by a program operating on the CPU.

  The storage unit 152 includes a ROM, a RAM, an EEPROM, a nonvolatile RAM, a flash memory, an HDD, and the like, and stores a program processed by the communication control unit 150, communication data, and the like. In addition, as will be described later, the storage unit 152 stores the communication quality of the reception slot performing packet communication in association with a plurality of reception slots.

  The display unit 154 includes a liquid crystal display, EL (Electro Luminescence), and the like, and can display an operation screen of an application, a telephone number of a communication partner, an address book, and the like. The operation unit 156 includes a movable switch such as a keyboard, a cross key, and a joystick, and accepts a user operation input.

  The communication quality acquisition unit 160 detects the communication quality of voice communication or packet communication. As the communication quality, RSSI (Received Signal Strength Indicator), FER (Frame Error Rate), or BER (Bit Error Rate) can be used. RSSI is the received radio wave intensity, which is the intensity of the analog signal received by the RF circuit 140. FER is an error rate in units of frames of the digital signal deframed by the channel codec unit 120, and BER is an error rate in units of bits of the digital signals.

  Note that RSSI can be acquired (measured) from burst signals intermittently transmitted by the base station during communication. Where the data with content is appropriately strong and weak, the burst signal is blown at a certain strength, so that it can be used as a reference.

  A case where packet communication is performed in the communication terminal 100 configured as described above will be described. FIG. 2 is a flowchart for explaining an operation example of the present embodiment. When packet communication is started in step 502, in step 504, the communication control unit 150 controls the channel codec unit 120 to make a time slot / carrier allocation request to the base station.

  FIG. 3 is a diagram for explaining a time slot. In the example shown in FIG. 3, one frame is 5 msec, which is divided into transmission (RX) and reception (TX) in half (TDD), and divided into four slots (TDMA). One transmission slot or reception slot is 625 μsec. Then, the transmission slots and the reception slots are paired to form time slots 1 to 4, and transmission / reception is performed.

  In step 506, when packet communication is started, the communication control unit 150 controls the channel codec unit 120 to perform communication using a plurality of time slots (for example, all four) in order to perform higher-speed communication. I do. At this time, there may be one or more base stations as communication partners. In extreme cases, all four time slots may be connected to different base stations.

  Also, in order to perform higher-speed communication, the communication control unit 150 controls the adaptive modulation / demodulation unit 130 to switch the modulation method as needed. Specifically, the communication control unit 150 monitors the communication quality (RSSI, FER, etc.) detected by the communication quality acquisition unit 160 and switches to a modulation method with a higher transfer rate when the communication quality is high. If it is low, switch to a modulation method with a slower transfer rate.

  In this embodiment, as shown in step 508, the communication quality detected by the communication quality acquisition unit 160 for each of a plurality of time slots assigned to packet communication is associated with each reception slot and stored in the storage unit. Store in 152. The communication quality to be stored is sufficient to accumulate, for example, for several seconds, and can be overwritten sequentially like a loop memory.

  If no voice communication is received in step 510, the communication quality storage in step 508 is continued until the packet communication is terminated in step 512. When packet communication ends in step 512, all time slots are released in step 514, and the process ends.

  When the voice communication is received at step 510, the slot allocation unit 122 requests the base station to allocate a time slot for voice communication at step 516. This request includes a reception slot that is currently used for packet communication and has the highest communication quality among a plurality of time slots based on the communication quality data stored in the storage unit 152. Specify a time slot. Thereby, the slot allocation part 122 can allocate the time slot containing the receiving slot with the best communication quality to voice communication. In detail, step 510 may be a continuous process of a request to release the time slot and an allocation request.

  The communication quality data stored in the storage unit 152 is RSSI, FER, BER or the like as described above, and is stored in association with each reception slot (for each reception slot). When the slot allocating unit 122 evaluates the communication quality of the time slot, it is preferable to use data having a certain time width (1 second to several seconds) instead of using only the latest last data. Specifically, each evaluation value can be calculated by averaging, integrating, or taking a deviation. This is because when the multipath delay signal is superimposed and fading occurs, fluctuations that cannot be ignored are generated in RSSI and FER. In addition, since the communication terminal 100 is a mobile body, the factor of fading changes at any time and is difficult to predict. However, by taking a time width as described above, it is possible to perform an appropriate evaluation.

  In step 518, voice communication is started, and when the user performs a call end operation in step 520, the voice communication is also ended. Stopping voice communication involves opening the time slot used for this. Therefore, in step 522, the slot allocation unit 122 transmits a request to the base station to allocate the time slot used for the voice communication to the packet communication. Thereby, packet communication can be performed as fast as possible. The time slot release request and the allocation request may be a set (or one) command. Thereby, packet communication can be performed as fast as possible.

  Then, the process proceeds to step 512, and the storage of the communication quality in step 508 is continued until the packet communication is completed. When packet communication ends in step 512, all time slots are released in step 514, and the process ends.

  According to the above configuration, voice communication can be started without degrading voice quality even when packet communication is performed using a plurality of time slots. In particular, by storing the communication quality in the storage unit, it is possible to evaluate the communication quality in a certain time width instead of the instantaneous value, and accordingly, it is possible to appropriately assign a time slot having a high communication quality to the voice communication. Further, it is only necessary to modify the control program, and the hardware is not changed. Therefore, the control program can be realized at a relatively low cost, and the present invention can be implemented in an existing communication terminal.

  In step 516, the slot allocation unit 122 has been described as allocating a single time slot for voice communication. However, when the communication control unit 150 can control slot diversity in which voice communication is performed using two time slots, the slot allocation unit 122 is based on the data stored in the storage unit 152 and includes a plurality of time slots. Two time slots including reception slots with better communication quality may be assigned to voice communication. Thereby, also when performing slot diversity, the quality of voice communication can be improved similarly.

[Second Embodiment]
A second embodiment of the portable wireless communication terminal according to the present invention will be described. FIG. 4 is a flowchart for explaining another operation example of the present embodiment. Parts that are the same as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the flowchart shown in FIG. 4, it is not necessary to store the communication quality of each reception slot (corresponding to step 508 in FIG. 2). As a normal (conventional) operation, the communication quality acquisition unit 160 detects the communication quality at any time for detecting the necessity of handover or switching the modulation method.

  When voice communication is received at step 510, at step 600, the slot allocation unit 122 requests the base station to allocate a time slot for voice communication. This request includes a time slot including a transmission slot which is currently used for packet communication and which is communicated by a modulation method having the highest transfer rate among the modulation methods set by the adaptive modulation / demodulation unit 130. specify. In packet communication, the communication quality is dynamically switched to a modulation method having a higher transfer rate as the communication quality is higher, so that the communication quality can be indirectly evaluated by the modulation method. Thereby, the slot allocation part 122 can allocate the time slot containing the receiving slot with the best communication quality to voice communication. In detail, step 600 may be a continuous processing of a request for releasing the time slot and an allocation request.

  In step 600, the slot allocation unit 122 has been described as allocating a single time slot for voice communication. However, when the communication control unit 150 can control slot diversity in which voice communication is performed using two time slots, the slot allocation unit 122 uses a modulation scheme with a higher transfer rate among a plurality of time slots. Two time slots including the transmission slot being communicated may be allocated for voice communication. Thereby, also when performing slot diversity, the quality of voice communication can be improved similarly.

[Third Embodiment]
A third embodiment of the portable wireless communication terminal according to the present invention will be described. FIG. 5 is a diagram illustrating a schematic configuration of a portable wireless communication terminal according to the third embodiment. Parts that are the same as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 5, the communication terminal 100 according to the present embodiment includes a moving speed detection unit 170. The moving speed detection unit 170 detects the moving speed of the communication terminal 100. Specifically, it may be detected by the frequency of handover, or the moving speed may be detected by referring to the geographical information from the serial number of the base station at the time of handover. Moreover, you may mount GPS (not shown) and may detect a moving speed, updating the present location at any time.

  As in the first and second embodiments, voice communication can be performed simultaneously using time slots (channels) with high communication quality even during packet communication. By the way, when the moving speed of the communication terminal 100 is fast, it may be difficult to maintain both communications. Specifically, when the communication terminal 100 is moving at high speed, the number of handovers increases, and an attempt is made to maintain the connection by antenna diversity or slot diversity. In such a case, if communication is attempted from all the time slots, there is a possibility that the connection of other communication terminals may be restricted around the passing base station.

  Therefore, when the moving speed exceeds a predetermined value, the communication control unit 150 may maintain voice communication and stop packet communication. As a result, voice communication is stable and the influence on other communication terminals can be reduced.

When the slot allocating unit 122 determines that the communication quality of the time slot allocated to the voice communication has deteriorated, the slot allocating unit 122 performs voice communication with other reception slots according to the communication quality acquired by the communication quality acquiring unit 160. May be assigned.

  As a result, the connection of the packet communication path that has not been selected for voice communication after switching to voice communication is continued, and the communication quality is acquired, so that even when the selected communication path deteriorates, it is newly added. It is possible to change the communication path without performing a search or the like.

  According to the above configuration, when the connection of the packet communication path that has not been selected for the voice communication is continued after the transition to the voice communication and the communication quality is acquired, the deterioration of the selected communication path occurs. However, the communication path can be shifted without newly searching.

  If the communication terminal 100 tries to communicate from all the time slots when trying to maintain the connection by slot diversity, there is a possibility that the connection of other communication terminals is restricted in the vicinity of the passing base station.

  As described above, even if the packet communication path that was not selected for voice communication continues to be connected after the transition to voice communication, and the communication quality is acquired, the selected communication path is deteriorated. It is possible to smoothly shift the communication path without performing a new search or the like, and it is possible to suppress restrictions on the connection of other communication terminals.

  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 each step in the wireless communication method of the present specification does not necessarily have to be processed in time series in the order described in the flowchart, and may partially include processing in parallel or a subroutine.

  The present invention can be used as a portable wireless communication terminal capable of performing voice communication and packet communication by the TDMA-TDD system.

DESCRIPTION OF SYMBOLS 100 ... Communication terminal, 110 ... Audio | voice conversion part, 112 ... Microphone, 114 ... Speaker, 120 ... Channel codec part, 122 ... Slot allocation part, 124 ... Codec part, 130 ... Adaptive modulation / demodulation part, 140 ... RF circuit, 142 ... Antenna , 150 ... communication control unit, 152 ... storage unit, 154 ... display unit, 156 ... operation unit, 160 ... communication quality acquisition unit, 170 ... movement speed detection unit

Claims (7)

A communication control unit that performs voice communication and packet communication in a TDMA-TDD system via a base station;
A slot allocation unit that allocates communication to a time slot composed of a pair of a reception slot and a transmission slot;
A communication quality acquisition unit that acquires the communication quality of each reception slot for a plurality of time slots assigned to packet communication;
A storage unit for storing the communication quality in association with the plurality of reception slots;
With
The slot allocating unit communicates the most communication among the plurality of time slots based on the data in the storage unit when an incoming request for voice communication is generated while performing packet communication using a plurality of time slots. A portable radio communication terminal characterized in that a time slot including a high-quality reception slot is assigned to voice communication. The communication control unit can control slot diversity for performing voice communication using two time slots,
2. The slot allocation unit allocates two time slots including a reception slot with better communication quality among the plurality of time slots to voice communication based on data in the storage unit. Mobile wireless communication terminal. If the slot allocating unit determines that the communication quality of the time slot allocated to the voice communication has deteriorated, the slot allocating unit performs voice communication with another reception slot according to the communication quality acquired by the communication quality acquiring unit. The portable wireless communication terminal according to claim 1, wherein the portable wireless communication terminal is assigned to the portable wireless communication terminal. A communication control unit that performs voice communication and packet communication in a TDMA-TDD system via a base station;
A slot allocation unit that allocates communication to a time slot composed of a pair of a reception slot and a transmission slot;
An adaptive modulation / demodulation unit capable of transmitting and receiving each of a plurality of time slots allocated to packet communication using different modulation schemes;
With
The slot allocating unit communicates with a modulation method having the highest transfer rate among the plurality of time slots when an incoming call request for voice communication is generated while performing packet communication using the plurality of time slots. A portable radio communication terminal characterized in that a time slot including a transmission slot is assigned to voice communication. The communication control unit can control slot diversity for performing voice communication using two time slots,
The said slot allocation part allocates two time slots including the transmission slot communicated by the modulation system with a higher transfer rate among these time slots to audio | voice communication, It is characterized by the above-mentioned. Portable wireless communication terminal.   The portable radio communication terminal according to claim 1 or 3, wherein the slot allocating unit allocates a time slot used for voice communication to packet communication after the voice communication ends. It further comprises a moving speed detector that detects the moving speed of the terminal,
The portable communication terminal according to claim 1 or 3, wherein the communication control unit maintains voice communication and stops packet communication when the moving speed exceeds a predetermined value.

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