JP2014192694A - Radio terminal - Google Patents

Abstract

Provided is a mobile terminal capable of avoiding interference even if frequency allocation is determined between wireless terminals without going through a base station.
In a wireless terminal 100 capable of communicating with another wireless terminal via a base station and capable of directly communicating without going through the base station, the own device is assigned to direct communication with the wireless terminal of the communication partner. A use frequency notification unit 116 that notifies the frequency and a storage unit 140 that stores the frequency notified from the use frequency notification unit of another wireless terminal, and refers to the storage unit 140 when the own device starts direct communication. Then, a frequency used by the own device is assigned while avoiding a frequency notified from another wireless terminal.
[Selection] Figure 2

Description

  The present invention relates to a portable terminal capable of directly communicating with each other without using a base station.

  In recent years, practical application of D2D (Device to Device) that allows wireless terminals such as mobile phones to directly communicate with each other without using a base station has been studied (for example, Non-Patent Document 1). By adopting direct communication, it is considered that base station congestion can be alleviated, radio resources can be effectively utilized, and base station power consumption can be reduced. Even in the event of a disaster such as an earthquake, even if a communication failure occurs because the communication demand exceeds the line capacity and congestion occurs or the base station is damaged, direct communication is possible. There is also a merit.

Mobile phones communicate directly with each other without going through a base station-What is "D2D" that is being standardized by 3GPP? , [Online], [Search March 5, 2013], <URL: http: //businessnetwork.jp/Detail/tabid/65/artid/2518/Default.aspx>

  If the mobile terminal is a system that communicates with multiple subcarriers (OFDMA, etc.), when the terminals communicate directly with each other, they discover neighboring terminals and at the same time allocate their frequencies (resource blocks) It is assumed that In this case, if frequency allocation is not appropriate, there is a possibility that interference may occur with respect to direct communication between other mobile terminals or communication between other mobile terminals and a base station.

  Therefore, an object of the present invention is to provide a mobile terminal capable of avoiding interference even if frequency allocation is determined between wireless terminals without going through a base station.

  In order to solve the above-described problem, a typical configuration of the present invention is a wireless terminal that can communicate with another wireless terminal via a base station and can directly communicate without going through the base station. The own device is provided with a use frequency notifying unit for notifying a frequency allocated for direct communication with a communication partner wireless terminal, and a storage unit for storing a frequency notified from a use frequency notifying unit of another wireless terminal. When starting the operation, the storage unit is referred to, and the frequency used by the own device is assigned while avoiding the frequency notified from other wireless terminals.

  Preferably, the wireless terminal monitors radio wave interference while continuing direct communication, and executes reassignment when interference occurs.

  When a frequency is reported from the used frequency notification unit of another wireless terminal, if the frequency overlaps with the frequency used by the own device for direct communication, the wireless terminal It is preferable to declare the frequency change.

  According to the present invention, it is possible to provide a mobile terminal capable of avoiding interference even if frequency allocation is determined between wireless terminals without going through a base station.

It is a figure explaining the network configuration assumed in this embodiment. It is a figure explaining the structure of the radio | wireless terminal concerning this embodiment. It is a flowchart explaining the operation | movement when a wireless terminal starts direct communication. It is a flowchart explaining the operation | movement during a wireless terminal direct communication.

  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 embodiments 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.

  FIG. 1 is a diagram for explaining a network configuration assumed in this embodiment. As shown in FIG. 1, in this embodiment, a wireless terminal 100 (terminal A, terminal B, terminal C, terminal D) can communicate with a wireless terminal of a communication partner via a base station 10. The wireless terminal 100 can also directly communicate without going through the base station. FIG. 1 illustrates a case where terminal A and terminal B and terminal C and terminal D communicate directly.

  In the following description, the term “wireless terminal 100” refers to all of the terminals A to D, and the term “terminal A”, “terminal B”, “terminal C”, and “terminal D” are used to distinguish the four wireless terminals 100, respectively. .

  FIG. 2 is a diagram illustrating the configuration of the wireless terminal according to the present embodiment. The wireless terminal 100 includes a terminal control unit 110, a wireless communication unit 130, and a storage unit 140.

  The terminal control unit 110 performs communication by transmitting and receiving radio waves via the wireless communication unit 130. In the present embodiment, the wireless communication unit 130 uses a system (for example, OFDMA) that performs communication using a plurality of subcarriers.

  The terminal control unit 110 includes a terminal selection unit 112, a frequency allocation unit 114, a used frequency notification unit 116, and an interference state detection unit 120. The terminal selection unit 112 searches for and selects a communication partner for direct communication. The detection can be performed, for example, by detecting a CCH signal emitted from the radio terminal 100. The detected wireless terminal 100 can be displayed in a list on the display unit of the wireless terminal 100 and can be directly selected by the user to start communication.

  The frequency allocation unit 114 negotiates with the selected wireless terminal and allocates a frequency used for direct communication. The used frequency notification unit 116 notifies the peripheral wireless terminals of the frequency allocated by the frequency allocation unit 114 for direct communication between the own device and the wireless terminal of the communication partner. This notification can be broadcast (distributed to an unspecified partner), for example, included in a CCH signal. The unusable frequency receiving unit 118 receives “frequency allocated to direct communication” transmitted from the other wireless terminal 100 and stores it in the unusable frequency list of the storage unit 140. Then, the frequency allocation unit 114 refers to the unusable frequency list in the storage unit 140 when the own device starts direct communication, and allocates the frequency used by the own device avoiding the frequency notified from other wireless terminals.

  The interference state detection unit 120 monitors and detects radio wave interference while direct communication is continued. The interference can be detected by, for example, an SNR (Signal-Noise-Ratio) at a frequency at which direct communication is performed.

  The operation of each part will be described below in order with reference to FIGS. FIG. 3 is a flowchart illustrating an operation when the wireless terminal 100 starts direct communication. FIG. 4 is a flowchart for explaining the operation during which the wireless terminal 100 is in direct communication. The radio terminal 100 performs prior avoidance of interference due to frequency allocation, and detection and handling of an interference state by the following operations.

  As shown in FIG. 3, first, the terminal selection unit 112 of the terminal A searches for a communication partner (terminal B), the user selects a communication partner terminal, and direct communication is started (step 200). The frequency allocation unit 114 of the terminal A negotiates the use frequency (resource block) with the frequency allocation unit 114 of the terminal B (step 202). Here, the frequency allocation unit 114 refers to the unusable frequency list in the storage unit 140 and avoids the frequencies registered in the list (frequency broadcast from other wireless terminals), and allocates the frequencies used by the own device. .

  Then, when the frequency to be used is determined, the frequency allocating unit 114 of the terminal A notifies the surrounding terminals of the used frequency (step 204). By this notification, as described below, the frequencies used by the terminal A are registered in the unusable frequency list of the peripheral terminals (terminals C and D).

  The non-frequency receiving unit 118 of the terminal C, which is a peripheral terminal, receives the used frequency notification transmitted by the terminal A (step 206). The terminal control unit 110 of the terminal C determines whether or not the own device is currently communicating (step 208). If communication is in progress (YES in step 208), the terminal control unit 110 of the terminal C determines whether the frequency used by the own device and the frequency notified from the terminal A overlap (interference) (step). 210) If there is no overlap, the process is terminated without any particular processing (NO in step 210). If they overlap (YES in step 210), the terminal A is notified of the frequency change (step 214).

  When the terminal C is not communicating (NO in step 208), the terminal C determines whether or not the frequency allocation unit 114 of its own device has completed the negotiation of the used frequency with the terminal D of the communication partner (step 216). . If the negotiation has not been completed (NO in step 216), the unusable frequency receiving unit 118 of the terminals C and D registers the used frequency notified from the terminal A in the unusable frequency list of the storage unit 140 (step 216). 218).

  If the negotiation has been completed (YES in step 216), the terminals C and D determine whether or not the use frequency determined by the negotiation and the use frequency broadcast from the terminal A overlap (interference) (step 220). . If there is no overlap (NO in step 220), the wireless communication units 130 of the terminals C and D start communication (step 222).

  If there is an overlap (YES in Step 220), the frequency allocation unit 114 of the terminals C and D determines whether there is an available free frequency (Step 224). If there is a free frequency (YES in step 224), the frequency allocation unit 114 of the terminals C and D negotiates again (step 226) and starts communication at a frequency that does not overlap with the terminal A (step 222).

  If there is no free frequency in terminals C and D (NO in step 224), frequency allocation unit 114 of terminals C and D declares a frequency change to terminal A (step 228). As a result, the frequency allocation unit 114 of the terminals A and B performs renegotiation (step 230) and changes the frequency to a frequency that does not overlap with the terminals C and D. In this way, the terminals A and B start communication (step 232).

  As shown in FIG. 4, when the terminals A and B start communication, the interference state detection unit 120 starts monitoring the interference state (step 240). Interference is detected for the frequency currently used for communication. Also, interference can be monitored for frequencies registered in the unusable frequency list of the storage unit 140, and the registration can be deleted from the unusable frequency list when radio waves are not being blown for that frequency.

  Then, the interference state detection unit 120 determines whether or not there is interference (step 242). If there is no interference (NO in step 242), communication and interference state monitoring are continued (step 244).

  If there is interference (YES in step 242), the frequency allocating unit 114 of the terminals A and B tries to reassign frequencies (step 244). Then, the interference state detection unit 120 of the terminals A and B determines whether interference due to frequency reassignment has been reduced (step 246). If alleviated (YES in step 246), the terminals A and B continue communication at the reassigned frequency (step 248), and continue to monitor the communication and interference state (step 252). If the interference is not reduced (NO in step 246), the communication and interference state monitoring is continued (step 252) while taking countermeasures against interference (step 250). As countermeasures against interference, frequency reassignment is further performed, frequency changes are reported to surrounding terminals, transmission power reduction is reported to surrounding terminals, and transmission power between terminals A and B is increased. can do.

  As described above, according to the configuration of the present invention, the peripheral wireless terminal can directly communicate with the peripheral wireless terminal by notifying the peripheral wireless terminal of the frequency determined by the negotiation with the communication partner terminal for direct communication. When starting, the frequency already used can be known in advance. Therefore, even if frequency allocation is determined between wireless terminals without going through a base station, it is possible to avoid interference with surrounding terminals in advance without determining frequency allocation only by negotiation with a communication partner. . In addition, since the intervention of the base station is unnecessary when starting direct communication, the processing amount and power consumption of the base station can be reduced. Moreover, frequency allocation can be maintained in an optimum state by monitoring interference and performing reallocation as needed even after direct communication is started.

  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 the example which concerns. 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.

  INDUSTRIAL APPLICABILITY The present invention can be used for portable terminals that can directly communicate with each other without using a base station.

DESCRIPTION OF SYMBOLS 100 ... Radio | wireless terminal, 110 ... Terminal control part, 112 ... Terminal selection part, 114 ... Frequency allocation part, 116 ... Use frequency alerting | reporting part, 118 ... Non-frequency receiving part, 120 ... Interference state detection part, 130 ... Wireless communication part, 140: Storage unit

Claims (3)

In a wireless terminal that can communicate with another wireless terminal via a base station and can directly communicate without going through a base station,
A used frequency notifying unit for notifying a frequency allocated to direct communication with the wireless terminal of the communication partner,
A storage unit for storing the frequency notified from the used frequency notification unit of another wireless terminal,
A wireless terminal that refers to the storage unit when the own device starts direct communication and allocates a frequency to be used by the own device avoiding a frequency notified from another wireless terminal.   The radio terminal according to claim 1, wherein the radio terminal monitors radio wave interference while continuing direct communication, and executes reassignment when the interference occurs.   When the frequency is reported from the used frequency notification unit of another wireless terminal, the wireless terminal overlaps the frequency used by the own device for direct communication. The radio terminal according to claim 1 or 2, wherein a frequency change is reported to the terminal.

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