JP2009207004A - Handover control method and terminal deice using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten ranging processing when carrying out handover. <P>SOLUTION: A control section 105 receives a control message from a second base station apparatus 20b and acquires reception electric power at the reception of the control message. The control section 107 acquires transmission electric power, at transmission of the control message by the second base station apparatus 20b. The control section 107 calculates the propagation delay time, from/to the second base station apparatus 20b, on the basis of the reception electric power and the transmission electric power of the control message, and adjusts the transmission timing of a control message to be transmitted to the second base station apparatus 20b for ranging process according to the calculated results. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a handover control technique, and more particularly to a handover control method for switching a connection from a currently communicating base station apparatus to another base station apparatus and a terminal apparatus using the handover control method.

In a radio communication system such as PHS (Personal Handyphone System), a base station apparatus is arranged for each radio zone. When the communication quality deteriorates due to being located at the end of the wireless zone, the terminal device performs handover for switching the connection from the currently communicating base station device to another base station device. In order to perform this handover at high speed, the terminal device searches for neighboring base station devices in advance and measures the electric field strength of the signal transmitted from each base station device. And, when the electric field strength of the received signal falls below a predetermined threshold during communication with the base station device, another base station that transmits the signal with the highest electric field strength from the currently communicating base station device Switch the connection to the device. (For example, Patent Document 1)
JP 2002-77964 A

  When a terminal device performs handover to another base station device, the terminal device executes a ranging process for adjusting transmission timing and the like. In order to improve user convenience, it is desirable to shorten the handover process including the ranging process. However, when the terminal device is located at the end of the radio zone of the handover source base station device, it is far away from the handover destination base station device, so it takes time for the ranging process and it is difficult to realize a high-speed handover process. Met.

  The present invention has been made in view of such a situation, and an object thereof is to provide a handover control method capable of shortening the ranging process and a terminal device using the handover control method.

  One embodiment of the present invention is a terminal device. The terminal device receives a first message transmitted from the base station device, and obtains first information related to transmission power when the first message is transmitted from the base station device. A first acquisition unit, a second acquisition unit that acquires second information related to received power when the first message is received, a request for handover to the base station device, and a base station device And an execution unit that executes a handover process including a ranging process, and the execution unit adjusts a transmission timing of a second message related to the ranging process based on the first and second information. The gist.

  Further, the execution unit defines a relational expression of propagation loss according to a propagation distance in advance, and by applying the first and second information to the relational expression, It is desirable to calculate a propagation delay time and adjust the transmission timing of the second message related to the ranging process according to the propagation delay time.

  The first message transmitted from the base station device includes the first information, and the first acquisition unit acquires the first information from the first message. Is desirable.

  According to the present invention, the time required for the ranging process can be shortened, and high-speed handover can be realized.

  The outline will be described before the present invention is specifically described. Embodiments of the present invention relate to a mobile communication system including a PAC (Paging Area Controller), a plurality of base station apparatuses, and terminal apparatuses, like a second generation cordless telephone system. The PAC connects a plurality of base station apparatuses at one end and a network at the other end. The plurality of base station devices each form a radio zone and connect to a terminal device in the radio zone. When the terminal device moves from one wireless zone to another wireless zone, the terminal device performs a handover from the source base station device to the destination base station device.

  In handover, the terminal apparatus disconnects the connection with the source base station apparatus and executes processing for establishing a connection with the destination base station apparatus. In addition, the terminal apparatus also performs ranging processing for adjusting signal transmission timing and the like with the base station apparatus that is the movement destination. In the ranging process, the base station apparatus detects an amount of deviation of the transmission timing from the ideal value for the link channel assignment request message transmitted from the terminal apparatus. Then, the base station apparatus calculates a correction amount for controlling the transmission timing in the terminal apparatus based on the deviation amount, and transmits it to the terminal apparatus by including it in the link channel assignment response message. The terminal device that has received the link channel assignment response message from the base station device transmits a link establishment request message to the base station device after adjusting the transmission timing based on the correction amount included in the link channel assignment response message. When the base station apparatus determines that the deviation amount from the ideal value of the transmission timing is not within a predetermined range for the link establishment request message and the transmission timing adjustment at the terminal apparatus is insufficient, the base station apparatus transmits the link establishment request message again to the terminal apparatus. Instruct to adjust timing. In this way, the terminal device and the base station device transmit and receive a plurality of messages until the deviation amount from the ideal value of the transmission timing in the terminal device converges within a predetermined range.

  Terminal devices often perform handover at the edge of a radio zone. When handover is performed at a position far away from such a base station apparatus, the amount of deviation of the transmission timing from the ideal value in the terminal apparatus tends to increase. On the other hand, since the amount of information for expressing the correction amount in the message is specified in advance, if handover is performed at the end of the radio zone, a plurality of messages will be transmitted and received for ranging processing, and high-speed handover is performed. Realization is difficult.

  Therefore, the terminal apparatus according to the embodiment of the present invention adjusts the transmission timing of the ranging process message to be earlier in consideration of the propagation delay time of the signal with the destination base station apparatus. Thereby, in the ranging process, the amount of deviation from the ideal value of the transmission timing in the terminal device is reduced, and high-speed handover can be realized.

  FIG. 1 is a conceptual diagram showing a configuration of a mobile communication system 1 in an embodiment of the present invention. The mobile communication system 1 includes a first base station device 20a, a second base station device 20b, a PAC 30, and a network 40, which are collectively referred to as a terminal device 10 and a base station device 20.

  The terminal device 10 communicates with the base station device 20 by a predetermined wireless communication method. Here, it is assumed that the OFDMA (Orthogonal Frequency Division Multiple Access) is applied to the TDMA / TDD (Time Division Multiple Access / Time Division Duplex) method as a wireless communication method.

  The base station device 20 is connected to the terminal device 10 by wireless communication at one end and connected to the PAC 30 by wire communication at the other end. Here, it is assumed that the first base station apparatus 20a is a source base station apparatus and the second base station apparatus 20b is a destination base station apparatus. The terminal device 10 disconnects the connection with the first base station device 20a and executes a handover to establish the connection with the second base station device 20b in response to a start instruction of either the terminal device 10 or the first base station device 20a. To do.

  The PAC 30 controls the base station device 20 to realize data transmission / reception via the network 40 between the terminal device 10 and a communication device (not shown). For example, data addressed to the terminal device 10 received from the network 40 is transmitted to the base station device 20. For this reason, the PAC 30 performs location registration with the terminal device 10 when the terminal device 10 is connected to the base station device 20. Further, when the terminal device 10 is handed over from the first base station device 20a to the second base station device 20b, a terminal connection change is executed with the base station device 20.

  The network 40 has a PAC 30 connected to one end and a communication device (not shown) connected to the other end. The network 40 is assumed to be, for example, a network using a TCP / IP (Transmission Control Protocol / Internet Protocol) method.

  FIG. 2 is a conceptual diagram showing a frame configuration of the TDMA / TDD scheme in the radio communication scheme of the mobile communication system 1. As shown in FIG. 2, a TDMA frame (hereinafter referred to as a frame) is composed of four time slots for uplink communication (terminal device 10 to base station device 20) and four time slots for downlink communication (base station device 20 to terminal device 10). Further, frames are arranged continuously. In the present embodiment, uplink communication and downlink communication are symmetric. Therefore, in the following, for convenience of explanation, only either uplink communication or downlink communication may be described, but the same applies to the other.

  In the radio communication system of the mobile communication system 1, as shown in FIG. 3, OFDMA is also applied, and a plurality of terminal devices 10 are allocated to one time slot. FIG. 3 shows the arrangement of time slots on the time axis in the direction of the horizontal axis, and the arrangement of subchannels on the frequency axis in the direction of the vertical axis. That is, the multiplexing on the horizontal axis corresponds to TDMA, and the multiplexing on the vertical axis corresponds to OFDMA. FIG. 3 includes the first time slot (shown as T1 in the figure) to the fourth time slot (shown as T4 in the figure) in one frame. 3 includes the first subchannel (indicated as SC1 in the figure) to the 18th subchannel (indicated as SC18 in the figure) in each time slot. In FIG. 2, “terminal device A” is in the second subchannel of the first time slot, “terminal device B” is in the second subchannel of the second time slot, and “terminal device B” is in the 16th sub of the third time slot. “Terminal device C” is assigned to the channel, and “terminal device D” is assigned to the thirteenth to fifteenth subchannels of the fourth time slot. In FIG. 3, the first subchannel is reserved as a control channel dedicated subchannel. In the figure, the first base station apparatus 20a assigns “control channel BS1” to the first subchannel of the first time slot, The base station apparatus 20b assigns “control channel BS2” to the first subchannel of the second time slot.

  FIG. 4 is a conceptual diagram showing a configuration of a subchannel block specified by a time slot and a subchannel in FIG. The horizontal direction in FIG. 3 is the time axis, and the vertical direction is the frequency axis. The numbers “1” to “24” indicate subcarrier numbers. In this way, the subchannel is composed of OFDM multicarrier signals. In the figure, “TS” corresponds to a training symbol, and includes known signals such as a symbol for synchronization detection and a symbol for estimating transmission path characteristics. “GS” corresponds to a guard symbol, and no effective signal is arranged here. “PS” corresponds to a pilot symbol, and is configured by a known signal. “DS” corresponds to a data symbol and is data to be transmitted.

  The terminal apparatus 10 and the base station apparatus 20 form a control channel with subchannel blocks, and establish a communication channel for transmitting and receiving data by transmitting and receiving a predetermined control message.

  The control channel is classified into a shared channel (hereinafter “CCH”) and a dedicated channel (hereinafter “ICH”) according to the access form. “CCH” is a channel that is shared and used by the terminal apparatuses 10 that access the base station apparatus 20. As shown in FIG. 3, “CCH” is formed by a specific time slot (hereinafter, a dedicated subchannel block) included in the control channel dedicated subchannel for each base station apparatus 20. On the other hand, “ICH” is a channel used individually by the terminal apparatus 10 that accesses the base station apparatus 20. “ICH” is formed of arbitrary subchannel blocks not included in the control channel dedicated subchannel for each terminal apparatus 10.

  The “CCH” type control channel includes a timing collection channel (hereinafter referred to as “TCCH”) for recognizing the terminal device 10 that requests allocation of a link channel, and a broadcast channel indicating the start of system information (hereinafter referred to as “BCCH”). And an incoming call information channel (hereinafter referred to as “PCH”) for notifying the terminal device 10 and a channel assignment control channel (hereinafter referred to as “SCCH”) for notifying a channel allocated to the terminal device 10.

  “TCCH” defines a plurality of combinations of data symbol values to be inserted in advance. For this reason, even if the base station apparatus 20 receives “TCCH” from a plurality of terminal apparatuses 10 at the same time, the base station apparatus 20 can recognize the plurality of terminal apparatuses 10 as long as the combinations of data symbol values are different. .

  In “BCCH”, as shown in FIG. 5A, a PHY frame including a PHY header, PHY data, CRC (Cyclic Redundancy Check), and TAIL is formed, and a control message is transmitted in the PHY layer. The same applies to “PCH”.

  On the other hand, the “ICH” type control channel includes a protocol control channel (hereinafter referred to as “ICCH”) for transmitting and receiving protocol messages, and an accompanying information channel (hereinafter referred to as “ACCH”) indicating the accompanying information of the channel allocated by the base station apparatus 20. ) Etc. are included.

  In “ICCH”, as shown in FIG. 5B, a MAC frame is formed by including a MAC header and MAC data in PHY data, and a control message is transmitted in the MAC layer. The same applies to “ACCH” and the like.

  An example of the control message format is shown in FIGS. The control message for broadcasting the wireless channel information by [BCCH] includes “message identifier”, “LCCH structure information”, and “transmission power information” as shown in FIG. The base station apparatus 20 configures a logical control channel (hereinafter referred to as “LCCH”) including “BCCH”, “PCH”, and “SCCH”, and intermittently transmits to the terminal apparatus 10 using dedicated subchannel blocks. “LCCH structure information” includes information (for example, interval value) related to the LCCH structure. The terminal device 10 can supplement the base station device 20 by receiving “LCCH structure information”. The “transmission power information” includes information regarding power when “BCCH” is transmitted from the base station apparatus 10. The terminal apparatus 10 calculates the propagation distance to the base station apparatus 20 based on “transmission power information”. This will be described later.

  In response to the link channel allocation request from the terminal apparatus 10, the control message that the base station apparatus 20 responds with “SCCH” is “message identifier”, “PRU number”, and “timing control” as shown in FIG. Information ". A “PRU number” is associated with each subchannel block in the frame, and the terminal apparatus 10 identifies the assigned subchannel block by the “PRU number”. The terminal device 10 performs the ranging process based on the “timing control information”. This will be described later.

  FIG. 7 is a conceptual diagram showing the configuration of the terminal device 10. In FIG. 7, an antenna 100 transmits and receives radio frequency signals.

  The radio unit 101 performs frequency conversion on the baseband signal from the transmission / reception unit 102 as a transmission operation to derive a radio frequency multi-carrier signal. In addition, as a reception operation, the radio frequency multicarrier signal received by the antenna 100 is frequency-converted to derive a baseband signal and output it to the transmission / reception unit 102. In addition, although the baseband signal is formed of an in-phase component (In-phase) and a quadrature component (Quadrature-phase), only one signal line is shown in FIG. 7 to simplify the description. The wireless unit 101 includes an AGC (Auto Gain Control) and an A / D (Analog / Digital) conversion unit.

  The transmission / reception unit 102 allocates the frequency domain signal transmitted from the modulation / demodulation unit 103 as a transmission operation to a plurality of subchannels to form a frequency domain multicarrier signal, converts this to a time domain signal, and converts the radio domain 101 Output to. Note that IFFT (Inversed Fast Fourier Transform) is used for the conversion from the frequency domain signal to the time domain signal.

  The transmission / reception unit 102 converts the time domain signal transmitted from the radio unit 101 as a reception operation into a frequency domain multi-carrier signal, separates it into frequency domain signals for each subcarrier, and outputs the frequency domain signal to the modem unit 103. Note that FFT (Fast Fourier Transform) is used for conversion from a time-domain signal to a frequency-domain multicarrier signal.

The modem unit 103 modulates the signal input from the IF unit 104 as a transmission operation. As a modulation method, BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 16QAM (Quadrature Amplitude Modulation), 64QAM, 256QAM, or the like is used.
The modulation / demodulation unit 103 demodulates the frequency domain signal transmitted from the transmission / reception unit 102 as a reception operation, and outputs the demodulated signal to the IF unit 104.

  IF section 104 outputs the signal demodulated by modem 103 as a receiving operation to a processing section (not shown). For example, when it corresponds to an audio signal, it is output to an audio processing unit (not shown). In addition, a signal input from a processing unit (not shown) is output to the modem unit 103 as a transmission operation.

  The control unit 105 controls the timing of the terminal device 10 as a whole. The control unit 105 includes an adjustment unit 1050, a handover processing unit 1051, and a ranging processing unit 1052, and executes a handover process with the base station apparatus 20.

  The adjustment unit 1050 captures “LCCH” that is intermittently transmitted by the second base station apparatus 20b in the “control channel BS2” of FIG. 3 while performing communication with the first base station apparatus 20a. When receiving the control message “BCCH” included in “LCCH”, adjustment section 1050 acquires the received power. Further, based on the “transmission power information” included in the control message, the transmission power when the control message “BCCH” is transmitted by the base station apparatus 20b is acquired.

  Coordinator 1050 applies the received power (Wr [db]) when the “BCCH” control message is received and the transmission power (Ws [db]) transmitted by base station apparatus 20b to the following equation. Then, the propagation loss (Lp [db]) is calculated.

調整部１０５０は、算出した伝搬損失を、伝搬距離をパラメータとして含む伝搬損失の推定式に適用し、次式により第２基地局装置２０ｂとの伝搬距離を算出する。

The adjustment unit 1050 applies the calculated propagation loss to a propagation loss estimation formula including the propagation distance as a parameter, and calculates the propagation distance from the second base station apparatus 20b using the following formula.

ここで、伝搬損失の推定式としては、奥村―秦式の推定式を用いる。なお、奥村―秦式の推定式は、「奥村義久ら，“陸上移動無線における伝搬特性の実験的研究”,通研実報,[16],9,pp. 1705-1764」に詳しいので、ここでの説明を省略する。

Here, as an estimation formula of propagation loss, an estimation formula of Okumura-Kashiwa formula is used. The Okumura-Kashiwa estimation formula is detailed in “Okumura Yoshihisa et al.,“ Experimental Study of Propagation Characteristics in Land Mobile Radio ”, Riken Actual Report, [16], 9, pp. 1705-1764] The description here is omitted.

  The adjustment unit 1050 applies the calculated propagation distance to the following equation to calculate the propagation delay time with the second base station device 20b.

基地局装置２０は、「TCCH」を受信したときの受信タイミングを、あらかじめ規定した理想値と比較することで、端末装置１０で補正すべき送信タイミングのずれ量を決定している。そこで、調整部１０５０は、算出した伝搬遅延時間に相当するデータシンボルだけ、「TCCH」の送信タイミングを早くするように調整する。これにより「TCCH」の送信タイミングがあらかじめ伝搬遅延時間に応じて調整されているため、基地局装置２０で受信したときの受信タイミングも理想値に近くなり、レンジング処理の短縮が期待できる。

The base station apparatus 20 determines the amount of transmission timing deviation to be corrected by the terminal apparatus 10 by comparing the reception timing when “TCCH” is received with an ideal value defined in advance. Therefore, adjustment section 1050 adjusts the transmission timing of “TCCH” to be advanced by only the data symbol corresponding to the calculated propagation delay time. Thereby, since the transmission timing of “TCCH” is adjusted in advance according to the propagation delay time, the reception timing when received by the base station apparatus 20 is also close to the ideal value, and shortening of the ranging process can be expected.

  The handover processing unit 1051 starts the handover process by transmitting an “ICCH” control message for requesting an access switching process to the first base station apparatus 20a. As a condition for starting handover, for example, when the RSSI of a signal received from the first base station apparatus 20a is smaller than a predetermined threshold, or when the number of errors detected by CRC is larger than a predetermined threshold Etc. are assumed. The start of the handover process may be instructed from the first base station apparatus 20a. This is because the degree of freedom of channel assignment of the first base station apparatus 20a is improved, and efficient utilization of radio resources can be expected.

  When the handover processing unit 1051 receives an instruction for access switching processing from the first base station apparatus 20a by the control message “ICCH”, the adjustment unit 1050 adjusts the transmission timing to the second base station apparatus 20b “TCCH”. To request link channel assignment processing in order to perform ranging processing.

  When the handover processing unit 1051 receives a response of the link channel assignment processing from the second base station apparatus 20b by the “SCCH” control message, it instructs the ranging processing unit 1052 to execute the ranging processing. Further, the handover processing unit 1051 performs carrier sense on the allocated link channel. When confirming that the RSSI (Receive Signal Strength Indication) is smaller than a predetermined level, that is, that the link channel is free, the handover processing unit 1051 transmits “ICCH” to the second base station apparatus 20b, and Request establishment processing.

  When the handover processing unit 1051 receives a response of the link establishment process from the second base station apparatus 20b by the control message “ICCH”, it performs an authentication process, a location registration process, etc., if necessary. Establishes a communication channel for transmitting and receiving data between them.

  Note that the handover processing unit 1051 may perform processing for establishing a communication channel with the second base station device 20b while maintaining a connection with the first base station device 20a. You may perform after cut | disconnecting the connection between the station apparatuses 20a. If the process is performed while maintaining the connection with the first base station apparatus 20a, the data communication will not be interrupted, so that a seamless handover can be realized. If processing is performed after the connection with the first base station device 20a is disconnected, the processing burden on the terminal device 10 is reduced, and power consumption can be reduced.

  The ranging processing unit 1052 refers to the “SCCH” control message transmitted from the second base station apparatus 20b according to an instruction from the handover processing unit 1051, and executes the ranging process. Specifically, the signal transmission timing is controlled based on the “timing control information” of the control message.

  The operation of the mobile communication system 1 having the above configuration will be described. FIG. 8 is a sequence diagram illustrating a procedure in which the terminal apparatus 10 performs a handover from the first base station apparatus 20a to the second base station apparatus 20b. The terminal device 10 determines handover when the RSSI of the received signal becomes smaller than a predetermined threshold during communication with the first base station device 20a (S100) (S101). The terminal device 10 receives the “BCCH” control message broadcast from the second base station device 20b, and captures the second base station device 20b. Furthermore, the terminal apparatus 10 calculates the propagation delay time with the second base station apparatus 20b based on the “transmission power information” included in the “BCCH” control message, and sets the transmission timing of “TCCH” accordingly. Adjust as soon as possible (S104). The terminal apparatus 10 performs a handover from the first base station apparatus 20a to the second base station apparatus 20b (S105), and establishes a communication channel with the second base station apparatus 20b (S106).

  FIG. 9 is a flowchart showing a disconnection procedure of the connection with the first base station apparatus 20a. The terminal device 10 transmits a control message “ICCH” and requests the first base station device 20a to perform access switching processing (S200). The first base station device 20a starts processing for disconnecting the connection with the terminal device 10 (S201). For example, when the terminal device 10 wishes to buffer data until it is connected to the second base station device 20b, the data addressed to the terminal device 10 is saved in the buffer. The first base station apparatus 20a transmits a control message “ICCH” and instructs the terminal apparatus 10 to switch access (S202). The terminal device 10 releases the subchannel block allocated as the communication channel, and disconnects from the first base station device 20a (S023).

  FIG. 10 is a flowchart showing a connection procedure for establishing a communication channel with the second base station apparatus 20b. The terminal apparatus 10 transmits “TCCH” in the dedicated subchannel block for which the second base station apparatus 20b broadcasts “LCCH”, and requests the second base station apparatus 20b to perform link channel allocation processing (S300). . When the second base station apparatus 20b recognizes the terminal apparatus 10 based on the “TCCH” waveform pattern, the second base station apparatus 20b determines a transmission timing for the terminal apparatus 10 to control based on the reception timing of “TCCH” (S301). The second base station apparatus 20b includes the information related to the subchannel block to which the link channel is allocated and the transmission timing in the “SCCH” control message and transmits the information to the terminal apparatus 10 (S302). The terminal device 10 performs the ranging process based on the information related to the transmission timing indicated by the “SCCH” control message (S303). The terminal device 10 transmits the “ICCH” control message in the subchannel block specified by the “SCCH” control message, and requests link establishment processing (S304).

  Here, when a plurality of terminal apparatuses 10 transmit the same “TCCH” waveform pattern, a request for link establishment processing may be transmitted from the plurality of terminal apparatuses 10 through one link channel. Therefore, the second base station apparatus 20b confirms whether or not a request for link establishment processing has been made from a plurality of terminal apparatuses 10 in one link channel (S305). If the link can be established with one terminal apparatus 10 through one link channel (Y in S305), the second base station apparatus 20b transmits a control message “ICCH” to notify the establishment of the link ( S306). If a link has already been established with another terminal device 10, the corresponding terminal device 10 starts over from the link channel assignment process (N in S305). When the terminal device 10 receives the link establishment notification by the “ICCH” control message (Y in S307), the terminal device 10 executes access establishment processing including authentication processing with the second base station device 20b, and performs communication. A channel is established (S308). On the other hand, if there is no link establishment notification from the base station apparatus 20b within a predetermined period, the link channel allocation request for the link is redone (N in S307).

  According to such an embodiment of the present invention, the following operational effects can be enjoyed.

  (1) The control unit 105 receives a control message from the second base station device 20b, acquires the received power when the control message is received, and transmits the control message when the second base station device 20b transmits the control message. The transmission power is acquired, the propagation delay time between the second base station apparatus 20b is calculated from the reception power and the transmission power of the control message, and the second base station apparatus 20b performs ranging processing according to the propagation delay time. Adjust the transmission timing of the control message to be transmitted. Thereby, the ranging process regarding transmission timing can be shortened, and a high-speed handover can be realized.

  (2) Further, the control unit 105 calculates the propagation loss from the transmission power and the reception power of the control message received from the second base station apparatus 20b, and applies it to the propagation loss estimation formula including the predefined propagation distance as a parameter. Then, the propagation delay time with the second base station apparatus 20b is calculated, and the transmission timing of the control message related to the ranging process is adjusted according to the propagation delay time. Thereby, the transmission timing can be adjusted accurately. In addition, the efficiency of the ranging process regarding the transmission timing is improved.

  (3) Moreover, the control part 105 acquires transmission power when the 2nd base station apparatus 20b transmits a control message based on the information regarding the transmission power contained in the control message received from the 2nd base station apparatus 20b. . Thereby, the transmission power of the control message can be easily obtained. Moreover, since it can acquire directly from the 2nd base station apparatus 20b, exact transmission power can be calculated | required. Further, since the estimation accuracy of the propagation delay time is improved, it is possible to realize a ranging process related to efficient transmission timing.

  Although the best mode for carrying out the present invention has been described above, the present invention is not limited to the configuration of this embodiment, and the scope of application of the present invention defined in the claims. As long as the functions of the configuration of the above-described embodiment can be achieved, various modifications are possible.

  For example, in the embodiment of the present invention, the estimation formula of the Okumura-Kashiwa equation was used as the propagation loss estimation equation, but the transmission loss was estimated by adding a correction coefficient or a correction term according to the installation environment to this equation. Also good.

1 is a conceptual diagram showing a configuration of a mobile communication system according to an embodiment of the present invention. Conceptual diagram showing the TDMA frame structure Conceptual diagram showing time-multiplexed time slots by OFDMA Conceptual diagram showing the configuration of the subchannel block Conceptual diagram showing the configuration of the control channel Conceptual diagram showing an example of control message format The conceptual diagram which shows the structure of the terminal device which concerns on embodiment of this invention Sequence diagram showing the handover procedure Flow chart showing the cutting procedure Flow chart showing the connection procedure

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Radio | wireless part 102 Transmission / reception part 103 Modulation / demodulation part 104 IF part 105 Control part 1050 Adjustment part 1051 Handover process part 1072 Ranging process part

Claims (3)

A receiving unit for receiving a first message transmitted from the base station device;
A first acquisition unit that acquires first information related to transmission power when the first message is transmitted from the base station device;
A second acquisition unit that acquires second information regarding received power when the first message is received;
An execution unit that requests handover to the base station device and executes handover processing including ranging processing with the base station device;
The execution unit adjusts the transmission timing of the second message related to the ranging process based on the first and second information.
A terminal device characterized by that. The execution unit preliminarily defines a relational expression of propagation loss according to a propagation distance, and applies the first and second information to the relational expression, thereby causing a propagation delay with the base station apparatus. Calculating time, and adjusting the transmission timing of the second message related to the ranging process according to the propagation delay time;
The terminal device according to claim 1. The first message transmitted from the base station device includes the first information, and the first acquisition unit acquires the first information from the first message.
The terminal device according to claim 1, wherein:

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