JP5961481B2 - Wireless communication apparatus, method and program - Google Patents

Description

  The present invention relates to a wireless communication apparatus, method, and program that repeat transmission / reception of subframes in accordance with a time division duplex (TDD) system, and more particularly, to a technique for adaptively changing the subframe length.

  Conventionally, a frequency division duplex (FDD) system and a TDD system are known as general bidirectional wireless communication systems. The FDD method is a method of performing transmission / reception using different frequencies. The TDD scheme shares the synchronized time among the radio stations, and divides the data on the time axis into a plurality of frames, so that the subframe in the downlink direction from the radio base station to the mobile station and the radio from the mobile station This is a method of alternately transmitting and receiving uplink subframes toward a base station at regular intervals. At a predetermined time, a downlink subframe is transmitted. At another predetermined time, an uplink subframe is transmitted, and transmission processing based on the sharing time is alternately performed.

  As a multi-user access system based on this TDD system, a TDMA (Time Division Multiple Access) / TDD system is generally known. In this TDMA / TDD system, a guard time is set between each subframe so that transmission signals from each user operating a plurality of mobile stations do not overlap on the time axis in the radio base station due to propagation delay or processing delay. A no-signal time gap period is set. This guard time is generally a fixed length. For example, in the mobile WiMAX standard (Non-Patent Document 1) known as a communication system for land mobile communication, 105.105 is provided between the downlink from the radio base station to the mobile station and the uplink from the mobile station to the radio base station. A fixed-length guard time of 7 μs is set, and a fixed-length guard time of 60 μs is set between the uplink and the downlink. Further, in the XGP standard (Non-Patent Document 2) standardized as a next-generation PHS communication method, guard times of 21.67 μs and 30 μs are set before and after an uplink burst for one slot, respectively.

  However, setting a fixed-length guard time limits the area in which communication is possible without transmission / reception signals interfering with each other. In the existing system, since the station placement design is limited to communication within an area of several kilometers called a cell, no problem arises, but long distance communication beyond the design area is difficult in principle. On the other hand, in order to perform long-distance communication, when a fixed-length guard time is set to a large value in accordance with the maximum propagation distance, there arises a problem that time utilization efficiency is greatly reduced.

  On the other hand, a method for improving the propagation efficiency of the TDD scheme has been proposed. This method accurately measures the amount of data to be transmitted and adaptively varies the ratio of uplink and downlink. According to this method, since the transmission / reception time ratio is determined according to the ratio of the transmission data amount between the uplink and the downlink, the delay in data transmission can be reduced. However, this method cannot improve the time utilization efficiency limited by the guard time.

JP 2007-49450 A

"Mobile WiMAX Standard", IEEE STD 802.16e-2005 ARIB STD-T95 version 2.1, “OFDMA / TDMA TDD Broadband Wireless Access System (Next Generation PHS)”

FIG. 11 is a transmission / reception timing chart of the TDD scheme when a fixed guard time is set in the prior art. The hatched portion indicates a fixed-length guard time, and _TUL indicates a subframe length (data length) and a fixed-length guard in transmission from a mobile station (MS: Mobile Station) to a radio base station (BS: Base Station). A time length of time is indicated, and _TDL indicates a time length of a subframe length (data length) and a fixed guard time in transmission from the base station to the mobile station. T represents the time length (frame length) of one frame made up of T _UL and T _DL , and Δτ ₁ represents the propagation delay time. (A) and (b) added to these parameters indicate parameters in FIG. 11 (a) or FIG. 11 (b).

FIG. 11A is a transmission / reception timing chart when the propagation delay time Δτ ₁ (a) is short (when it is shorter than the propagation delay time Δτ ₁ (b) in FIG. 11B described later). When the mobile station starts signal transmission, the radio base station that shares time information with the mobile station enters a signal reception standby state, but actually starts to receive the signal because of the propagation delay time Δτ ₁ (a). Only after it has passed. Then, when the radio base station starts signal transmission according to the shared time information, the mobile station enters a signal reception standby state, but actually starts to receive the signal because of the propagation delay time Δτ ₁ (a). Only after it has passed. Then, the radio base station starts signal transmission according to the shared time information. Such transmission / reception processing is repeated. Here, a shift in reception timing due to a propagation delay can be absorbed by the guard time, so that a transmission / reception signal does not interfere.

FIG. 11B is a transmission / reception timing chart when the propagation delay time Δτ ₁ (b) is long (when the propagation delay time Δτ ₁ (a) in FIG. 11A is longer). The transmission / reception timings of the mobile station and the radio base station are the same as those in FIG. 11A, and the reception timing shift due to the propagation delay can be absorbed by the guard time, so that the transmission / reception signals do not interfere.

The case 11 the propagation delay time .DELTA..tau ₁ shown in (a) (a) is short and FIG. 11 (b) to the propagation delay between .DELTA..tau ₁ shown (a) is compared with the case long, 11 (a) In FIG. 11B, the ratio of transmission data (transmission subframe) and reception data (reception subframe) in one frame, that is, time utilization efficiency, is lower. This is because the transmission data lengths in FIG. 11 (a) and FIG. 11 (b) are the same, and the reception data lengths are also the same. The guard time in FIG. 11 (a) <the guard time in FIG. 11 (b), T (A) <T (b), T _UL (a) <T _UL (b), T _DL (a) <T _DL (b), Δτ ₁ (a) <Δτ ₁ (b) This is because the guard time occupancy rate for one frame length T is relatively increased when performing long-distance communication.

  As described above, in the existing communication system using the TDD scheme, when performing long-distance communication with a large propagation delay, it is necessary to set the fixed-length guard time to a large value in accordance with the maximum propagation distance. However, there is a problem that the time use efficiency indicating the ratio of the transmitted / received data significantly decreases.

  Accordingly, the present invention has been made to solve the above-described problems, and its purpose is to make the occupancy rate of the guard time relative to the frame length relatively variable by adaptively varying the frame length of the signal according to the propagation distance. An object of the present invention is to provide a wireless communication apparatus, method, and program that can be reduced and realize highly efficient communication.

  In order to achieve the above object, a radio communication apparatus according to the present invention provides a subframe within a frame length of a predetermined time according to a time division duplex (TDD) scheme between a radio base station and a mobile station. In a wireless communication apparatus that performs transmission and reception and repeats transmission and reception of the subframe for each frame length, a frame synchronization detection unit that detects a head of the received subframe and generates a frame synchronization detection timing pulse; and the frame synchronization detection unit A frame period detection counter that counts signal pulses synchronized with an internal clock between the previous frame synchronization detection timing pulse generated this time and the current frame synchronization detection timing pulse and obtains the number of pulses, and the frame period detection counter The frame reception cycle is calculated from the number of pulses obtained by A propagation delay time calculation unit that calculates a propagation delay time between the radio base station and the mobile station based on the period, and a long frame length if the propagation delay time calculated by the propagation delay time calculation unit is long A frame length setting unit for setting the frame length so that the frame length is shortened when the propagation delay time is short, and a time corresponding to the frame length set by the frame length setting unit A long subframe is transmitted.

  The wireless communication apparatus according to the present invention further includes a transmission processing unit that generates transmission subframes by performing transmission processing including processing of predetermined encoding and modulation schemes on transmission data, and the received subframes. On the other hand, a reception processing unit that performs a predetermined reception process, and performs high-frequency frequency conversion on the transmission subframe and the reception subframe in the previous period, and switches between transmission of the transmission subframe and reception of the reception subframe via the transmission / reception antenna. A transmission / reception high-frequency unit to perform, a reception subframe length indicating the time length of the reception subframe, a transmission subframe length indicating the time length of the transmission subframe, and a code in the transmission processing unit for processing the next transmission data The transmission subframe is transmitted after the reception of the reception subframe is completed based on the modulation and modulation scheme As described above, a transmission timing signal after a predetermined time has elapsed from the time of the frame synchronization detection timing pulse generated by the frame synchronization detection unit and output to the transmission processing unit, and from the time of the transmission timing signal, A transmission timing control unit that generates a switching timing signal and outputs the switching timing signal to the transmission / reception high-frequency unit after the delay time due to the processing of the transmission processing unit elapses, and the transmission processing unit receives a transmission timing signal from the transmission timing control unit From the reception to transmission when the transmission / reception high-frequency unit receives a switching timing signal from the transmission timing control unit. It is characterized by starting a process including switching.

  Also, in the wireless communication device according to the present invention, the propagation delay time calculation unit transmits from the calculated frame reception cycle, the reception subframe length, the transmission subframe length, and reception in the preset transmission / reception high-frequency unit. The propagation delay time between the radio base station and the mobile station is calculated based on the processing time including switching to the mobile station.

  Further, the wireless communication method according to the present invention performs transmission / reception of a subframe within a frame length of a predetermined time between a wireless base station and a mobile station according to a time division duplex method, and transmits / receives the subframe to the frame length In a wireless communication method that repeats every time, a step of receiving a subframe, a step of detecting a head of the received subframe, generating a frame synchronization detection timing pulse, a previously generated frame synchronization detection timing pulse, and thereafter Based on the frame reception period, a step of counting signal pulses synchronized with an internal clock and calculating the number of pulses, a step of calculating a frame reception period from the number of pulses, Calculating a propagation delay time between the radio base station and the mobile station Setting the frame length so that the frame length becomes long when the propagation delay time is long, and the frame length is shortened when the propagation delay time is short, and according to the set frame length Transmitting a time-length subframe.

  Furthermore, a program according to the present invention causes a computer to function as the wireless communication device.

  As described above, according to the present invention, the frame length of the signal is adaptively varied according to the propagation distance. Thereby, the occupation rate of the guard time in the frame length can be relatively reduced, and highly efficient communication can be realized.

1 is a schematic diagram illustrating a communication system in which a radio base station provided with a radio communication device according to an embodiment of the present invention and a mobile station face each other on a one-to-one basis. It is a block diagram which shows the structure of the radio | wireless communication apparatus by embodiment of this invention. It is a figure which shows the structure of a TDD sub-frame. It is a figure which shows the waveform of the preamble signal added to the head of a TDD sub-frame. It is a figure which shows the movement correlation value for detecting the frame head in a frame synchronization detection part. It is a flowchart which shows a frame length setting process. It is a flowchart which shows the process of transmission timing control. It is a timing chart for demonstrating the frame length setting process and the process of transmission timing control. (A) is a transmission / reception timing chart when the frame length is fixed. FIG. 6B is a transmission / reception timing chart when the frame length is variable in the embodiment of the present invention. It is a figure explaining time utilization efficiency (eta) when the original frame length is made into n times. In the prior art, it is a transmission / reception timing chart of a TDD system when a fixed-length guard time is set.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram illustrating a communication system in which a radio base station provided with a radio communication apparatus according to an embodiment of the present invention and a mobile station face each other on a one-to-one basis. Each of the wireless base station and the mobile station is provided with a wireless communication apparatus according to an embodiment of the present invention. The distance between transmission and reception between the radio base station and the mobile station is 0 to 100 km, and it is assumed that communication is performed based on the TDD scheme in a state of being separated from each other. Mobile stations are mounted on, for example, helicopters, airplanes, bullet trains, and the like.

  FIG. 2 is a block diagram showing a configuration of the wireless communication apparatus according to the embodiment of the present invention. In the communication system shown in FIG. 1, the configuration of the radio communication apparatus provided in the radio base station is the same as the configuration of the radio communication apparatus provided in the mobile station. The wireless communication apparatus 1 will be described as being provided in a wireless base station. The wireless communication device 1 includes a signal processing unit 2, a transmission / reception high-frequency unit 3, and a transmission / reception antenna 4. The signal processing unit 2 includes an A / D (Analog / Digital) conversion unit 10, an orthogonal demodulation unit 11, a frame synchronization detection unit 12, an AFC (Automatic Frequency Control) unit 13, a PHY (PHYsical layer). : Physical layer) header demodulation / analysis unit 14, OFDM (Orthogonal Frequency Division Multiplexing) demodulation unit 15, demapping unit 16, decoding unit 17, received data holding unit 18, frame length / processing delay detection unit 19 , Adaptive modulation control unit 20, transmission timing calculation unit 21, transmission timing control unit 22, transmission data holding unit 23, encoding unit 24, mapping unit 25, OFDM modulation unit 26, GI (Guard Interval) addition unit 27 , TDD frame generation unit 28, quadrature modulation unit 29, D / A (Digital / Analog) conversion unit 30, frame And a period detection counter 31, the propagation delay time calculation unit 32 and the frame length control section (frame length setting unit) 33. The transmission / reception high frequency unit 3 includes a transmission / reception switching unit 40, a reception high frequency unit 41, and a transmission high frequency unit 42.

  Here, the A / D converter 10, the quadrature demodulator 11, and the frame of the signal processor 2 perform processing from the reception signal received from the transmission / reception high-frequency unit 3 until the frame synchronization detection unit 12 detects the frame synchronization. The synchronization detection unit 12 constitutes a reception processing unit. Further, the transmission system from the encoding unit 24 to the D / A conversion unit 30 performs processing from encoding the transmission data to D / A conversion and outputting the transmission signal to the transmission / reception high-frequency unit 3. A transmission processing unit is configured. In FIG. 2, solid arrows indicate transmission / reception signals, and dotted arrows indicate control signals and the like.

[Reception processing]
First, processing for receiving a signal transmitted from a mobile station will be described. The wireless communication device 1 of the wireless base station is basically in a signal reception standby state except when performing transmission processing.

  FIG. 3 is a diagram illustrating a configuration of a TDD subframe. This TDD subframe shows a configuration example of a signal transmitted from a mobile station, and a preamble which is a known signal is added to the head of a plurality of OFDM symbols. In addition to this preamble, a PHY header, a PHY payload, and Consists of a PHY trailer.

  FIG. 4 is a diagram showing a waveform of a preamble signal added to the head of the TDD subframe shown in FIG. In FIG. 4, the horizontal axis represents time, and the vertical axis represents the amplitude of the preamble signal. As shown in FIG. 4, the preamble signal of the TDD subframe transmitted from the mobile station has a time waveform having a regular amplitude at a predetermined period.

  In the radio communication apparatus 1 of the radio base station shown in FIG. 2, the transmission / reception high-frequency unit 3 performs high-frequency frequency conversion on the TDD subframe and switches transmission / reception of the TDD subframe via the transmission / reception antenna 4. The transmission / reception switching unit 40 of the transmission / reception high-frequency unit 3 connects the transmission / reception antenna 4 and the reception high-frequency unit 41 with an RF switch to wait for reception except when transmitting, and moves through the transmission / reception antenna 4. A TDD subframe signal (received signal) transmitted from the station is received. The reception high-frequency unit 41 receives the reception signal from the transmission / reception switching unit 40 and converts the radio frequency of the input reception signal into a signal in an IF (Intermediate Frequency) band that allows digital signal processing. Note that the power supply of the reception high-frequency unit 41 is always ON, unlike the transmission high-frequency unit 42 described later.

  The A / D conversion unit 10 of the signal processing unit 2 receives an IF signal from the reception high frequency unit 41 of the transmission / reception high frequency unit 3 and converts the analog IF signal into a digital IF signal. The quadrature demodulator 11 receives a digital IF signal from the A / D converter 10 and performs digital quadrature demodulation. The frame synchronization detection unit 12 receives a digital quadrature demodulated signal (a TDD subframe signal) from the quadrature demodulation unit 11 and detects the head of the TDD subframe.

  FIG. 5 is a diagram showing a movement correlation value for detecting the frame head in the frame synchronization detection unit 12. In FIG. 5, the horizontal axis represents time, and the vertical axis represents the movement correlation value. The frame synchronization detection unit 12 performs a movement correlation process between the input signal (received signal) and a known preamble in the time domain, and calculates a movement correlation value shown in FIG. Then, the frame synchronization detection unit 12 detects a correlation peak from the moving correlation value in the time domain, and detects the head of the TDD subframe from the time position of the detected correlation peak. When the frame synchronization detection unit 12 detects the beginning of the frame, the frame synchronization detection unit 12 generates a frame synchronization detection timing pulse indicating the time position of the beginning of the TDD subframe, and outputs the complex signal value of the detected correlation peak to the AFC unit 13 for frame synchronization. The detection timing pulse is output to the transmission timing calculation unit 21 and the frame period detection counter 31.

  Returning to FIG. 2, the AFC unit 13 inputs the complex signal value of the correlation peak detected from the frame synchronization detection unit 12, and uses the phase information of the complex signal value corresponding to the frequency deviation to Correct the frequency deviation between. The PHY header demodulation / analysis unit 14 receives the TDD subframe signal with the frequency deviation corrected from the AFC unit 13 and demodulates the PHY header following the preamble. Then, the PHY header demodulation / analysis unit 14 analyzes the demodulated PHY header to extract the signal format (modulation method, coding rate, etc.) of the received signal, and encodes and modulates the signal format of the received signal. Is output to the OFDM demodulator 15 and the adaptive modulation controller 20. The PHY header demodulation / analysis unit 14 outputs the demodulated PHY header to the frame length / processing delay detection unit 19.

  The OFDM demodulator 15 receives the TDD subframe signal from the AFC unit 13 and also receives the received signal encoding and modulation scheme information from the PHY header demodulator / analyzer 14 and follows the PHY header of the TDD subframe. Demodulate the data stored in the PHY payload. The demapping unit 16 receives the demodulated data from the OFDM demodulator 15 and performs demapping. The decoding unit 17 receives the demapped data from the demapping unit 16, performs decoding (error correction), and holds the decoded data in the reception data holding unit 18 as reception data. The reception data held in the reception data holding unit 18 is output to the upper layer.

  The frame length / processing delay detector 19 receives the PHY header demodulated from the PHY header demodulator / analyzer 14 and transmits the next data transmitted from the adaptive modulation controller 20 from the radio communication device 1 of the radio base station. The information of the encoding and modulation system (of the next transmission signal) is input. The frame length / processing delay detection unit 19 detects (extracts) the reception frame length (reception subframe length) and the transmission frame length (transmission subframe length) from the input PHY header, and inputs the next transmission signal that has been input. Based on the encoding and modulation schemes and the transmission frame length, the processing delay time in the transmission system is detected (set). Here, in the PHY header of the received TDD subframe, the reception frame length indicating the time length of the received TDD subframe and the transmission frame length of the TDD subframe transmitted by the wireless communication device 1 are stored. It shall be. The wireless communication apparatus 1 may hold the transmission frame length when transmitting the TDD subframe, and the frame length / processing delay detection unit 19 may use the held transmission frame length. .

  The frame length / processing delay detection unit 19 outputs the reception frame length and the processing delay time in the transmission system (transmission signal encoding / modulation processing time) to the transmission timing calculation unit 21. For example, the frame length / processing delay detection unit 19 sets the encoding / modulation processing time of the transmission signal using a table in which the encoding scheme, the modulation scheme, the transmission frame length, and the processing delay in the transmission system are associated with each other. The frame length / processing delay detection unit 19 searches for processing delays using a table in which coding schemes, modulation schemes, and processing delays are associated with each other, and uses a predetermined formula based on processing delays and transmission frame lengths to transmit signals. The encoding / modulation processing time may be set.

  The adaptive modulation control unit 20 inputs the received signal encoding and modulation scheme information from the PHY header demodulation / analysis unit 14, and also receives the transmission frame length from the frame length control unit 33, and encodes the received reception signal. And the modulation scheme are set to the encoding and modulation scheme of data to be transmitted next by the radio communication apparatus 1 of the radio base station. In addition, the adaptive modulation control unit 20 controls the encoding unit 24, the mapping unit 25, and the OFDM modulation unit 26 to process the transmission data corresponding to the input transmission frame length. As a result, the encoding unit 24, which will be described later, reads out an amount of transmission data corresponding to the transmission frame length, coding rate, and modulation scheme. Here, the encoding and modulation scheme information of the received signal received from the mobile station is determined by the mobile station based on the quality information of the signal received from the radio base station in the past. Adaptive modulation control that determines the optimal encoding and modulation scheme based on the quality information of the signal received from the base station, stores the encoding and modulation scheme in the PHY header of the TDD subframe, and transmits it to the radio base station It is assumed that

  The adaptive modulation control unit 20 outputs the set information of the next transmission signal encoding and modulation scheme to the frame length / processing delay detection unit 19, the encoding unit 24, the mapping unit 25, and the OFDM modulation unit 26. Thereby, the adaptive modulation control unit 20 can control the encoding unit 24, the mapping unit 25, and the OFDM modulation unit 26 of the transmission system.

  When the TDD scheme is used, since the propagation path is common between the uplink from the mobile station to the radio base station and the downlink from the radio base station to the mobile station, the quality of the signal received from the mobile station is reduced. You may make it observe with a wireless base station. In this case, the adaptive modulation control unit 20 of the radio communication apparatus 1 provided in the radio base station determines the encoding and modulation scheme of the transmission signal based on the observed quality information.

  The transmission timing calculation unit 21 receives a frame synchronization detection timing pulse indicating the head time position of the TDD subframe from the frame synchronization detection unit 12, and receives the received frame length and the code of the transmission signal from the frame length / processing delay detection unit 19. Enter the conversion / modulation processing time. Then, the transmission timing calculation unit 21 sets a transmission timing adjustment time indicating a time from the frame synchronization detection timing to the transmission timing based on the reception frame length, the encoding / modulation processing time of the transmission signal, etc. The frame synchronization detection timing pulse, the transmission timing adjustment time, and the transmission signal encoding / modulation processing time are output to the transmission timing control unit 22.

  The transmission timing control unit 22 inputs the frame synchronization detection timing pulse, the transmission timing adjustment time, and the transmission signal encoding / modulation processing time from the transmission timing calculation unit 21, and sets the transmission timing adjustment time from the time of the frame synchronization detection timing pulse. At the timing after the elapse, a transmission timing signal is generated, and the generated transmission timing signal is output to the transmission data holding unit 23. The transmission timing control unit 22 generates a switching timing signal at a timing after the transmission signal encoding / modulation processing time elapses from the time of the transmission timing signal, and the generated switching timing signal is transmitted to the transmission / reception switching unit 40 and Output to the transmission high-frequency unit 42. This switching timing signal is a signal indicating the timing of turning on the power of the transmission high-frequency unit 42 of the transmission / reception high-frequency unit 3 and switching the RF switch of the transmission / reception switching unit 40 from the reception high-frequency unit 41 to the transmission high-frequency unit 42. It is also a signal indicating the timing at which reception of the transmitted TDD subframe is completed.

  The transmission timing signal and the switching timing signal are output at different timings when the encoding and modulation scheme processing for transmission is started, and the transmission high-frequency unit 42 of the transmission / reception high-frequency unit 3 is turned on to transmit / receive This is because the timing for switching the RF switch of the switching unit 40 from the reception high-frequency unit 41 to the transmission high-frequency unit 42 is different. As a result, the transmission signal is D / A converted by the D / A conversion unit 30, and at the same time, the power of the transmission high-frequency unit 42 is turned on, and the transmission / reception switching unit 40 connects the transmission / reception antenna 4 and the transmission high-frequency unit 42. The A transmission signal (a TDD subframe signal) is output from the transmission / reception antenna 4 as a radio signal.

  After the transmission high-frequency unit 42 outputs a transmission signal via the transmission / reception switching unit 40 and the transmission / reception antenna 4, the transmission / reception switching unit 40 immediately connects the transmission / reception antenna 4 and the reception high-frequency unit 41, and the power supply of the transmission high-frequency unit 42 is Turns off. As a result, the wireless communication device 1 enters a standby state for signal reception from the mobile station.

[Transmission process]
Next, processing for transmitting a signal from the radio base station will be described. The transmission data holding unit 23 receives the transmission data from the upper layer and holds it in the buffer. When the transmission timing signal is input from the transmission timing control unit 22, the transmission data holding unit 23 reads the transmission data from the buffer at the input timing and encodes it. 24.

  The encoding unit 24 receives the transmission frame length, encoding and modulation scheme information from the adaptive modulation control unit 20, and transmits a predetermined amount of transmission according to the transmission frame length, encoding and modulation scheme from the transmission data holding unit 23. Enter the data. Then, the encoding unit 24 encodes the transmission data with the encoding method indicated by the input information. The encoded transmission data is subjected to error correction processing in the decoding unit of the mobile station. The mapping unit 25 receives the transmission frame length, encoding and modulation scheme information from the adaptive modulation control unit 20, and also receives the encoded data from the encoding unit 24, based on the modulation scheme indicated by the input information. In order to assign one bit or a plurality of bits of the input predetermined amount of data to one subcarrier, the input data is assigned (mapped) to one signal point on the complex plane. The OFDM modulation unit 26 receives information on the transmission frame length, encoding, and modulation scheme from the adaptive modulation control unit 20, and also receives data mapped from the mapping unit 25, and based on the modulation scheme indicated by the input information The complex signal value for each subcarrier is converted into a time domain signal by FFT calculation for the input predetermined amount of data. The GI addition unit 27 receives a time domain signal from the OFDM modulation unit 26 and adds a GI to the input time domain signal.

  The TDD frame generation unit 28 inputs the time domain signal to which the GI is added from the GI addition unit 27, receives the transmission frame length from the frame length control unit 33, and inputs a plurality of OFDM symbols to the input transmission frame length. So that one TDD subframe is generated. The orthogonal modulation unit 29 performs digital orthogonal modulation on the TDD subframe generated by the TDD frame generation unit 28. The D / A conversion unit 30 converts the digital signal digitally quadrature-modulated by the quadrature modulation unit 29 into an analog signal. The transmission signal converted by the D / A conversion unit 30 is output to the transmission high-frequency unit 42 of the transmission / reception high-frequency unit 3.

  The frame period detection counter 31, the propagation delay time calculation unit 32, and the frame length control unit 33 will be described in the frame length setting process described later.

  The transmission high-frequency unit 42 and the transmission / reception switching unit 40 receive a switching timing signal from the transmission timing control unit 22 and turn on the power of the transmission high-frequency unit 42 at the time when the switching timing signal is input. The antenna 4 and the transmission high-frequency unit 42 are connected. The transmission high-frequency unit 42 receives the transmission signal from the D / A conversion unit 30, converts the IF band of the input transmission signal into a radio frequency band, amplifies the transmission signal, and transmits the signal via the transmission / reception switching unit 40 and the transmission / reception antenna 4. It outputs as a signal (signal of a TDD subframe). Thereafter, the transmission / reception switching unit 40 connects the transmission / reception antenna 4 and the reception high-frequency unit 41, the power of the transmission high-frequency unit 42 is turned off, and the wireless communication device 1 enters a standby state for signal reception from the mobile station.

  By such reception processing and transmission processing, the signal transmitted from the radio base station is received by the mobile station. When the reception is completed, the signal is transmitted again from the mobile station to the radio base station, and the above operation is repeatedly performed. .

[Frame length setting processing]
Next, the frame length setting process will be described. The frame length setting process is performed by the frame period detection counter 31, the propagation delay time calculation unit 32, and the frame length control unit 33. FIG. 6 is a flowchart showing the frame length setting process.

  The frame period detection counter 31 receives a frame synchronization detection timing pulse indicating the start time position of the TDD subframe from the frame synchronization detection unit 12 (step S601), and the previously input frame synchronization detection timing pulse and the currently input frame synchronization detection pulse. Signal pulses synchronized with the internal clock are counted between the detection timing pulses, and the counted number of pulses is output to the propagation delay time calculation unit 32 (step S602).

The propagation delay time calculation unit 32 inputs the number of pulses counted between the frame synchronization detection timing pulses from the frame period detection counter 31, and calculates the frame reception period T _cnt from the input number of pulses (step S603). Since the number of pulses is obtained from a signal synchronized with the internal clock and the time per pulse is known, the frame reception cycle T _cnt can be calculated from the number of pulses. Then, the propagation delay time calculation unit 32 calculates the calculated frame reception cycle T _cnt , the uplink subframe length T _UL , the downlink subframe length T _DL , and the transmission / reception switching unit 40 and the transmission high-frequency unit 42 of the transmission / reception high-frequency unit 3. The propagation delay time Δτ ₁ is calculated from the transmission high-frequency part activation / RF switch switching transition time Δτ _{5 in} accordance with the following equation (step S604).
[Equation 1]
Δτ ₁ = {(T _cnt −T _UL −T _DL ) / 2} −Δτ ₅ (1)
The uplink subframe length _TUL is the received frame length detected by the frame length / processing delay detector 19 and is extracted from the PHY header of the TDD subframe that is the received signal. The downlink subframe length T _DL is also the transmission frame length detected by the frame length / processing delay detector 19 and is the transmission frame length of the TDD subframe transmitted in the previous transmission process. Further, the transmission high-frequency unit activation / RF switch switching transition time Δτ ₅ is a time set in advance according to the wireless communication device 1, and will be described in detail later. The basis for deriving the formula (1) will be described later with reference to FIG.

Frame length control unit 33 receives the propagation delay time .DELTA..tau ₁ from the propagation delay time calculation unit 32, based on the propagation delay time .DELTA..tau _1, when the propagation delay time .DELTA..tau ₁ is long so that the frame length becomes longer, the propagation If the delay time Δτ ₁ is short, the frame length is set so as to be short (step S605).

For example, the frame length control unit 33 sets the frame length to 5 ms when the propagation delay time Δτ ₁ is less than 83 μs using a table in which the correspondence relationship between the propagation delay time Δτ ₁ and the frame length is defined. When the delay time Δτ ₁ is 83 μs or more and less than 166 μs, the frame length is set to 10 ms. When the propagation delay time Δτ ₁ is 166 μs or more and less than 333 μs, the frame length is set to 20 ms and the propagation delay time Δτ ₁ is 333 μs or more and 667 μs. If not, the frame length is set to 40 ms. As a result, in communication with a maximum propagation distance of 100 km, the time utilization efficiency can be maintained at 98% or higher regardless of the length of the propagation distance.

The frame length control unit 33 calculates the transmission frame length from the set frame length, and outputs the transmission frame length to the adaptive modulation control unit 20 and the TDD frame generation unit 28 (step S606). The transmission frame length is calculated from the frame length, the reception frame length, the propagation delay time Δτ _1, and the transmission high-frequency unit activation / RF switch switching transition time Δτ ₅ . Referring to FIG. 9B described later, the transmission frame length is: transmission frame length T _DL1 = frame length T _{1 -reception} frame length T _UL1 -2 × propagation delay time Δτ ₁ -2 × transmission high-frequency unit activation / RF Calculated by the switch switching transition time Δτ ₅ ), and this equation is the same as the equation (1).

(Transmission timing control)
Next, transmission timing control will be described. FIG. 7 is a flowchart showing a transmission timing control process. This flowchart shows only main processing for transmission timing control.

  In FIG. 7, the wireless communication device 1 receives a TDD subframe from the mobile station (step S701), and the frame synchronization detection unit 12 detects the frame head of the TDD subframe and generates a frame synchronization detection timing pulse ( Step S702).

  The PHY header demodulation / analysis unit 14 extracts the encoding and modulation scheme of the reception signal from the PHY header of the TDD subframe (step S703), and the adaptive modulation control unit 20 determines the encoding and modulation scheme of the reception signal. A transmission signal encoding and modulation scheme is set (step S704). The frame length / processing delay detection unit 19 detects (extracts) the reception frame length and the transmission frame length from the PHY header of the TDD subframe, and determines the transmission system delay from the encoding and modulation scheme of the transmission signal and the transmission frame length. Time (encoding / modulation processing time of transmission signal) is detected (set) (step S705). And the transmission timing calculation part 21 calculates transmission timing adjustment time using Numerical formula (2) mentioned later (step S706). Then, the transmission timing control unit 22 generates and outputs a transmission timing signal after the elapse of the transmission timing adjustment time from the time of the frame synchronization detection timing pulse, and encodes / modulates the transmission signal from the time of the transmission timing signal. After the elapse of time, a switching timing signal is generated and output (step S707).

  The transmission system encoding unit 24 to D / A conversion unit 30 performs processing according to the encoding and modulation scheme of the transmission signal and the transmission frame length at the time of the transmission timing signal (step S708). At the time of the switching timing signal, the transmission high-frequency unit 42 is turned on, and the transmission / reception switching unit 40 connects the transmission / reception antenna 4 and the transmission high-frequency unit 42 (step S709). Then, the wireless communication device 1 transmits a TDD subframe from the wireless base station (step S710).

  In the mobile station, the same processing as that of the above-described radio base station is performed, a signal is transmitted again from the mobile station to the radio base station, and the above processing is repeated.

[Transmission timing adjustment time Δτ ₃ ]
As described above, the transmission timing calculation unit 21 starts the encoding and modulation scheme processing for transmission based on the frame synchronization detection timing pulse, the reception frame length, the encoding / modulation processing time of the transmission signal, and the like. The transmission timing adjustment time Δτ ₃ indicating the time between the frame synchronization detection timing and the output of the transmission timing signal for starting the transmission processing is calculated.

Specifically, the transmission timing adjustment time Δτ ₃ is calculated by the following equation.
[Equation 2]
Δτ ₃ = T _UL −Δτ ₂ −Δτ ₄ + Δτ ₅ (2)
Here, _TUL is the TDD subframe length of the signal transmitted from the mobile station to the radio base station, and corresponds to the reception frame length detected by the frame length / processing delay detector 19. Δτ ₂ is a processing delay time from when a signal is received to when synchronization is detected, and is set in advance. Δτ ₄ is the time required for the encoding and modulation system processing in the transmission system from the encoding unit 24 to the D / A conversion unit 30, and is the transmission system detected by the frame length / processing delay detection unit 19 This corresponds to a delay time (encoding / modulation processing time of the transmission signal). Δτ ₅ is a transmission high-frequency unit activation / RF switch switching transition time that is set in advance. The transmission high-frequency unit 42 is switched from the power-on to the stable operation and the RF switch of the transmission / reception switching unit 40 is set to the transmission / reception antenna 4. When comparing with the transition time for switching from the receiving antenna to the transmitting antenna in FIG.

If the frame length T is defined as the cycle of the transmission signal, it is expressed by the following equation.
[Equation 3]
T = T _UL + T _DL + 2Δτ ₁ + 2Δτ ₅ (3)
_TDL is a TDD subframe length of a signal transmitted from the radio base station to the mobile station. In the conventional TDD scheme, the frame length is generally fixed. However, in this embodiment, the guard time is adaptively varied in accordance with the propagation delay time Δτ ₁ , so the frame length T increases or decreases according to the equation (3). .

[Timing of frame length setting processing and transmission timing control processing]
Next, the timing of frame length setting processing and transmission timing control processing will be described. FIG. 8 is a timing chart for explaining these processes.

The transmission signal (a) of the MS is a TDD subframe transmitted from the mobile station MS, and the reception signal (b) of the BS is a transmission / reception antenna 4 of the BS that is a radio base station separated from the mobile station by a predetermined length. This is a TDD subframe received via the. The propagation delay time Δτ ₁ is the time from when the mobile station starts transmitting a signal until the radio base station starts receiving the signal. That is, the radio base station starts receiving the signal after the propagation delay time Δτ _{1 has} elapsed since the mobile station started transmitting the signal. The propagation delay time Δτ ₁ is a time that depends on the distance between the mobile station and the radio base station.

The frame synchronization detection timing pulse (c) is a signal indicating the timing at which the frame synchronization detection unit 12 detects the frame head of the TDD subframe. The processing delay time Δτ ₂ is a processing time in the A / D conversion unit 10, the orthogonal demodulation unit 11, and the frame synchronization detection unit 12 of the signal processing unit 2 illustrated in FIG. The frame synchronization detection unit 12 detects the beginning of the frame at a timing after the processing delay time Δτ _{2 has} elapsed since the signal was received until the synchronization was detected. The processing delay time Δτ ₂ can be grasped at the circuit design stage of the wireless communication device 1.

The transmission timing signal (before modulation) (d) of the BS is a signal generated by the transmission timing control unit 22, and is transmitted from the encoding unit 24 to the D / A conversion unit 30 of the signal processing unit 2 illustrated in FIG. It is a signal which shows the timing which a transmission system starts the process of the encoding and modulation system for transmission. The transmission timing adjustment time Δτ ₃ is the time from the frame synchronization detection timing to the transmission timing, and the transmission timing calculation unit 21 also considers a transmission high-frequency unit activation / RF switch switching transition time Δτ ₅ described later, It is calculated in advance using the above-described equation (2) so that the transmission signal is transmitted from the transmission / reception antenna 4 at the timing (f) described later.

  The switching timing signal (e) is a signal generated by the transmission timing control unit 22, and the transmission system from the encoding unit 24 to the D / A conversion unit 30 of the signal processing unit 2 shown in FIG. This is a signal indicating the timing at the time after the processing delay time has elapsed since the start of the encoding and modulation system processing. In other words, the transmission signal generated in the transmission system from the encoding unit 24 to the D / A conversion unit 30 is frequency-converted and amplified by the transmission high-frequency unit 42 of the transmission / reception high-frequency unit 3 and then output from the transmission / reception antenna 4. Therefore, this is a signal indicating the timing of an instruction for turning on the power of the transmission high-frequency unit 42 and switching the RF switch of the transmission / reception switching unit 40. This is almost the same timing as the completion of reception of the signal from the mobile station. Here, when the power of the transmission high-frequency unit 42 is turned on / off, the transmission signal is amplified while the signal is received by the radio base station, and the signal interferes with the circuit of the reception high-frequency unit 41 on the receiving side. In order to prevent this, a power amplifier (not shown) provided in the transmission high-frequency unit 42 is mainly activated and stopped.

The encoding / modulation processing time Δτ ₄ is a time required for the encoding and modulation processing in the transmission system from the encoding unit 24 to the D / A conversion unit 30 of the signal processing unit 2 shown in FIG. Yes, it is possible to grasp at the stage of circuit design of the wireless communication device 1. In addition, in order to output a transmission signal from the transmission / reception antenna 4 at the timing of a transmission signal (f) of a BS, which will be described later, the transmission system from the encoding unit 24 to the D / A conversion unit 30 performs encoding in advance. Conversion / modulation processing is started.

The transmission signal (f) of the BS is a TDD subframe transmitted via the transmission / reception antenna 4 of the BS that is a radio base station. In the actual wireless communication device 1, the startup time from when the transmission high-frequency unit 42 is powered on until it stably operates and the transition time for switching the RF switch of the transmission / reception switching unit 40 from the reception antenna to the transmission antenna at the transmission / reception antenna 4 are It is finite. If the larger of both times is the transmission high-frequency unit activation / RF switch switching transition time Δτ ₅ , the transmission of the BS is performed at the timing when the transmission high-frequency unit activation / RF switch switching transition time Δτ _{5 has} elapsed from the time of completion of signal reception The signal (f) is output via the transmission / reception antenna 4.

In an actual apparatus, the start-up time from when the transmission high-frequency unit 42 is powered on until stable operation and the transition time for switching the RF switch from the reception antenna to the transmission antenna are finite. If the larger of both times is Δτ ₅ , a signal is transmitted from the antenna of the radio base station at a timing when Δτ _{5 has} elapsed since the completion of signal reception.

The received signal (g) of the MS is a TDD subframe received by the MS, which is a mobile station that is a predetermined distance away from the radio base station. The propagation delay time Δτ ₁ is the time from when the radio base station starts transmitting a signal until the mobile station starts receiving the signal, and is the same as the propagation delay time Δτ ₁ described above. . That is, the mobile station starts receiving the signal after the propagation delay time Δτ _{1 has} elapsed since the radio base station started transmitting the signal.

  In the mobile station, processing similar to that of the radio base station is performed. Then, the MS transmission signal (h) is transmitted again from the mobile station to the radio base station at this timing, and the BS reception signal (i) is received again at this timing at the radio base station. . Similarly, the frame synchronization detection timing pulse (j) is generated again by the frame synchronization detection unit 12 at this timing.

The pulse (k) counted by the frame period detection counter 31 is a signal synchronized with the internal clock. The frame period detection counter 31 counts the number of pulses between the timing of the frame synchronization detection timing pulse (c) and the timing of the frame synchronization detection timing pulse (j). Then, the propagation delay time calculation unit 32 calculates the frame reception period T _cnt from the number of pulses, and the propagation delay time Δτ ₁ is calculated using the equation (1).

Here, since the frame reception cycle T _cnt is also the time from the beginning of the BS reception signal (b) to the beginning of the BS reception signal (i), the following equation is derived from FIG.
[Equation 4]
T _cnt = T _UL +2 (Δτ ₅ + Δτ1) + T _DL (4)
The formula (1) is derived from the formula (4). Then, the frame length control unit 33 sets the frame length from the propagation delay time Δτ ₁ .

[Transmission / reception timing at radio base stations and mobile stations]
Next, transmission / reception timings in the radio base station and the mobile station will be described. FIG. 9 is a transmission / reception timing chart when the frame length is fixed (a) and when the frame length in the embodiment of the present invention is variable (b). T _UL1 and T ′ _UL1 indicate the TDD subframe length in transmission from the mobile station MS to the radio base station BS, and T _DL1 and T ′ _DL1 indicate TDD in transmission from the radio base station to the mobile station. Indicates the subframe length. T ₁ and T ₂ are the time length (frame length) of one frame, G is the guard time of the mobile station and the radio base station, Δτ ₁ is the propagation delay time, Δτ ₅ is the transmission high-frequency unit activation and RF switch switching transition time Indicates. The guard time G is the total time of the propagation delay time Δτ ₁ and the transmission high-frequency unit activation / RF switch switching transition time Δτ ₅ .

FIG. 9A is a transmission / reception time chart when the frame length is fixed. When the mobile station starts signal transmission, the radio base station enters a signal reception standby state, but actually starts receiving the signal after the propagation delay time Δτ _{1 has} elapsed. When the radio base station starts signal transmission, the mobile station enters a signal reception standby state. However, the signal actually starts to be received after the propagation delay time Δτ _{1 has} elapsed. Then, the radio base station starts signal transmission, and such transmission / reception processing is repeated. Since the frame length T ₁ is fixed in repeated transmission / reception processing, the transmission frame lengths T _UL1 and T _DL1 have the same time length. Thus, the time efficiency indicating a ratio of the transmitted and received data in the frame length T ₁ is the same in transmission and reception processing of the repetition.

In FIG. 9A, when long-distance communication with a large propagation delay is performed, since the propagation delay time Δτ ₁ becomes longer, the guard time G and the frame length T ₁ also become longer. As a result, the time utilization efficiency is lowered. To do. In order to solve this, in the embodiment of the present invention, when the propagation delay time Δτ ₁ is long, the frame length T ₁ becomes long, and when the propagation delay time Δτ ₁ is short, the frame length T ₁ becomes short. The frame length T ₁ is variably controlled according to the propagation delay time Δτ ₁ .

FIG. 9B is a transmission / reception timing chart when the frame length is made variable according to the propagation delay time Δτ ₁ in the embodiment of the present invention. In the repeated transmission / reception processing similar to FIG. 9A, the mobile station calculates the propagation delay time Δτ ₁ and sets the next frame length T _2, and sets the transmission frame length T ₂ from the set frame length T _2. 'Calculate _UL1 and start sending. Similarly, the radio base station calculates the propagation delay time .DELTA..tau ₁ sets the next frame length T _2, calculated from the frame length T ₂ which sets the transmission frame length T _'DL1 of next transmission signal, transmission To start. Frame length T ₂ are, in the process of transmitting and receiving repetition, because the variable according to the propagation delay time .DELTA..tau _1, the transmission frame length T _'UL1, T' _DL1 becomes variable as well. Thus, the time efficiency indicating a ratio of the transmitted and received data in the frame length T ₂ are, a different value in the process of transmitting and receiving repetition.

When long-distance communication with a large propagation delay is performed, the propagation delay time Δτ ₁ becomes longer, so the guard time G also becomes longer. However, a longer frame length T ₂ in accordance with the propagation delay time .DELTA..tau _1, was set to a transmission frame length T _'UL1, T' also _DL1 becomes longer. Thus, relatively reduce the occupancy of the guard time G in the frame length T _2, it is possible to avoid a decrease in time efficiency, it is possible to realize a highly efficient communication.

FIG. 10 is a diagram for explaining the time utilization efficiency η when the original frame length is n times. T indicates the time length (frame length) of one frame, T _UL , T _DL , nT _UL , and nT _DL indicate the transmission frame length, and T _GT receives the reception signal after the transmission signal transmission is completed. Indicates the time between starting. The upper part of FIG. 10 shows a timing chart in the original frame length, and the lower part of FIG. 10 shows a timing chart after the original frame length has become n times.

As shown in the upper part of FIG. 10, the time use efficiency η in the case of the original frame length is expressed by the following equation.
[Equation 5]
η = (T _UL + T _DL ) / (T _UL + T _DL + T _GT ) (5)

As shown in the lower part of FIG. 10, the time use efficiency η when the original frame length is n times is expressed by the following equation.
[Equation 6]
η = (T _UL + T _DL ) / (T _UL + T _DL + T _GT / n) (6)

For example, when a TDD subframe having a frame length T = 40 ms is configured with respect to the frame length T = 5 ms, the guard time is relatively 1/8. Thus, when performing long-distance communication with a large propagation delay, the propagation delay time Δτ ₁ becomes long, but the transmission frame lengths T _UL and T _DL are made long according to the propagation delay time Δτ ₁ . As a result, it is possible to relatively reduce the guard time occupation ratio in the frame length T, to avoid a decrease in the time utilization efficiency η, and to realize highly efficient communication.

As described above, according to the wireless communication device 1 according to the embodiment of the present invention, the frame length is adaptively varied according to the propagation distance between the wireless base station and the mobile station. Specifically, the frame period detection counter 31 counts signal pulses synchronized with the internal clock between the previous frame synchronization detection timing pulse and the current frame synchronization detection timing pulse generated by the frame synchronization detection unit 12. The number of pulses was calculated. Then, the propagation delay time calculation unit 32 calculates the frame reception period T _cnt from the number of pulses, and calculates the propagation delay time Δτ ₁ using the above equation (1). Then, frame length control unit 33, based on the propagation delay time .DELTA..tau _1, when the propagation delay time .DELTA..tau ₁ is long so that the frame length is long, transmission frame to set the next frame length, corresponding to the frame length The length was calculated. As a result, a transmission signal having a transmission frame length calculated by the frame length control unit 33 is transmitted. Since the transmission frame length is calculated so as to increase when the propagation delay time Δτ ₁ is long, the occupancy rate of the guard time in the frame length can be relatively reduced, and highly efficient communication can be realized. It becomes possible. Therefore, time utilization efficiency can be improved regardless of the propagation distance between the radio base station and the mobile station facing each other.

  In addition, according to the wireless communication device 1 according to the embodiment of the present invention, an optimum frame length that instantaneously follows the fluctuation of the propagation delay can be set, so that a high speed using a helicopter, an airplane, a bullet train, etc. Even when the propagation distance changes greatly in mobile communication, highly efficient communication can be realized without being restricted by the communication area.

  Note that a normal computer can be used as the hardware configuration of the wireless communication device 1 according to the embodiment of the present invention. The wireless communication device 1 is configured by a computer including a volatile storage medium such as a CPU and a RAM, a non-volatile storage medium such as a ROM, an interface, and the like. Each function of the signal processing unit 2 and the transmission / reception high-frequency unit 3 included in the wireless communication device 1 is realized by causing the CPU to execute a program describing these functions. These programs can also be stored and distributed in a storage medium such as a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), optical disk (CD-ROM, DVD, etc.), semiconductor memory, etc. You can also send and receive.

  The present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the technical idea thereof. For example, the configuration of the wireless communication apparatus 1 shown in FIG. 2 is an example, and the present invention is not limited to this configuration, and receives a signal in a signal waiting state and waits for the completion of signal reception. Thus, the transmission / reception signal may be transmitted to the transmission destination without interference.

DESCRIPTION OF SYMBOLS 1 Wireless communication apparatus 2 Signal processing part 3 Transmission / reception high frequency part 4 Transmission / reception antenna 10 A / D conversion part 11 Orthogonal demodulation part 12 Frame synchronization detection part 13 AFC part 14 PHY header demodulation and analysis part 15 OFDM demodulation part 16 Demapping part 17 Decoding Unit 18 reception data holding unit 19 frame length / processing delay detection unit 20 adaptive modulation control unit 21 transmission timing calculation unit 22 transmission timing control unit 23 transmission data holding unit 24 encoding unit 25 mapping unit 26 OFDM modulation unit 27 GI addition unit 28 TDD frame generation unit 29 Quadrature modulation unit 30 D / A conversion unit 31 Frame period detection counter 32 Propagation delay time calculation unit 33 Frame length control unit 40 Transmission / reception switching unit 41 Reception high frequency unit 42 Transmission high frequency unit

Claims (5)

A subframe is transmitted and received within a frame length of a predetermined time according to a time division duplex (TDD) method between the radio base station and the mobile station, and the transmission and reception of the subframe is repeated for each frame length. In a wireless communication device,
A frame synchronization detection unit that detects the beginning of the received subframe and generates a frame synchronization detection timing pulse;
Between the previous frame synchronization detection timing pulse and the current frame synchronization detection timing pulse generated by the frame synchronization detection unit, a signal pulse synchronized with the internal clock is counted, and a frame period detection counter for obtaining the number of pulses,
Calculating a frame reception period from the number of pulses obtained by the frame period detection counter, and calculating a propagation delay time between the radio base station and the mobile station based on the frame reception period;
Frame length setting for setting the frame length so that the frame length is increased when the propagation delay time calculated by the propagation delay time calculation unit is long, and the frame length is shortened when the propagation delay time is short And comprising
A radio communication apparatus, wherein a subframe having a time length corresponding to the frame length set by the frame length setting unit is transmitted. The wireless communication device according to claim 1,
Furthermore, a transmission processing unit that generates transmission subframes by performing transmission processing including processing of a predetermined encoding and modulation scheme for transmission data;
A reception processing unit that performs predetermined reception processing on the received subframe;
A transmission / reception high-frequency unit that performs high-frequency frequency conversion on the transmission subframe and the reception subframe in the previous period, and performs switching between transmission of the transmission subframe and reception of the reception subframe via the transmission / reception antenna;
Based on the reception subframe length indicating the time length of the reception subframe, the transmission subframe length indicating the time length of the transmission subframe, and the encoding and modulation scheme in the transmission processing unit that processes the next transmission data Generating a transmission timing signal after elapse of a predetermined time from the time of the frame synchronization detection timing pulse generated by the frame synchronization detection unit so that the transmission subframe is transmitted after the reception of the reception subframe is completed. And a transmission timing control unit that generates a switching timing signal and outputs it to the transmission / reception high-frequency unit after a delay time due to the processing of the transmission processing unit has elapsed from the time of the transmission timing signal. With
When the transmission processing unit receives a transmission timing signal from the transmission timing control unit, the transmission processing unit starts transmission processing for generating a transmission subframe from the transmission data,
The wireless communication apparatus, wherein the transmission / reception high-frequency unit starts a process including switching from reception to transmission when a switching timing signal is input from the transmission timing control unit. The wireless communication device according to claim 2,
The propagation delay time calculation unit is based on the calculated frame reception cycle, the reception subframe length, the transmission subframe length, and a processing time including switching from reception to transmission in the transmission / reception high-frequency unit set in advance. And calculating a propagation delay time between the radio base station and the mobile station. In a wireless communication method, between a radio base station and a mobile station, transmits and receives subframes within a frame length of a predetermined time according to a time division duplex method, and repeats transmission and reception of the subframes for each frame length.
Receiving a subframe;
Detecting the head of the received subframe and generating a frame synchronization detection timing pulse;
Counting the signal pulse synchronized with the internal clock between the previously generated frame synchronization detection timing pulse and the subsequently generated frame synchronization detection timing pulse, and obtaining the number of pulses;
Calculating a frame reception period from the number of pulses;
Calculating a propagation delay time between the radio base station and the mobile station based on the frame reception period;
Setting the frame length so that the frame length is increased when the propagation delay time is long, and the frame length is decreased when the propagation delay time is short;
Transmitting a subframe having a time length according to the set frame length;
A wireless communication method comprising:   The program for functioning a computer as a radio | wireless communication apparatus as described in any one of Claim 1 to 3.

Images