JP2007324773A - Communication method, and base station apparatus using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce interference to an existing user caused by a signal to a terminal device before synchronization establishment. <P>SOLUTION: The base station apparatus performs multiplexed communications for a plurality of terminal devices within an identical time zone. The base station apparatus comprises a validation portion 40, a generator 50, and a transmitter. The validation portion 40 checks presence or absence of an existing terminal device performing communications with the base station apparatus, using opportunity when there is a communication start request from a terminal device which should perform communications with the base station apparatus as a trigger. The generator 50 generates a signal for establishing synchronization between the terminal device sending the communication start request and the base station apparatus. The transmitter transmits the signal generated by the generator 50 to the terminal device if presence of any existing terminal device is not checked by the validation portion, and shortens and transmits the signal generated by the generator 50 to the terminal device if presence of any existing terminal device is checked. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless communication technique, and more particularly to a communication method for transmitting a synchronization signal to a terminal device to be communicated and a base station device using the communication method.

In wireless communication, effective use of limited frequency resources is generally desired. In particular, with the spread of mobile phones and second-generation cordless telephone systems, the demand is further increased. One technique for meeting this demand is the spatial multiplexing method. Spatial multiplexing is a technology for communicating with a plurality of terminal devices while suppressing mutual interference at the same frequency and the same timing by adjusting the antenna directivity pattern for each of the plurality of terminal devices. It is. In such a spatial multiplexing system, signals between a plurality of terminal devices are separated according to the antenna directivity pattern. An adaptive array antenna technique is applied to form the directivity pattern. Conventionally, in adaptive array antenna technology, interference with other terminal devices has been further reduced by periodically reducing the signal strength of a synchronization signal transmitted to the terminal device (see, for example, Patent Document 1). .)
International Publication No. 02/054815 Pamphlet

  In general, in the adaptive array antenna technique, existing terminal devices that are spatially multiplexed are adjusted so that they are directed toward each other so that they do not interfere with each other. However, transmission to a terminal device whose synchronization with the base station device is disconnected has a problem that directivity cannot be adjusted and interference is caused to other terminal devices.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a communication method capable of reducing interference with other terminal devices due to a signal to the terminal device before synchronization is established, and a base station device using the same. There is.

  In order to solve the above problems, a base station apparatus according to an aspect of the present invention is a base station apparatus that performs communication by multiplexing a plurality of terminal apparatuses in the same time zone, and the base station apparatus, the terminal apparatus, Generating a synchronization signal for establishing synchronization, a data signal for a terminal device for which synchronization is established by the synchronization signal, and transmitting data signals generated by the generation unit from a plurality of antennas A transmitting unit that controls the directivity of the antenna and that does not control the directivity of the antenna when the synchronization signal generated by the generating unit is transmitted from a plurality of antennas. When transmitting the synchronization signal, the transmission unit shortens the length of the synchronization signal when there is a data signal multiplexed with another terminal device and in the same time zone as the synchronization signal.

  According to this aspect, when transmitting a synchronization signal, the length of the synchronization signal is shortened when there is a data signal multiplexed to the other terminal apparatus in the same time zone as the synchronization signal. Thus, interference with other terminal devices can be reduced in a time zone when the synchronization signal is not transmitted.

  When transmitting the shortened synchronization signal to the terminal device, the transmission unit may notify the terminal device that the shortened synchronization signal is transmitted prior to transmission of the synchronization signal. Thus, when transmitting the shortened synchronization signal to the terminal device, the terminal device is synchronized without delay by notifying the terminal device that the shortened synchronization signal is transmitted prior to the transmission of the synchronization signal. Since processing can be executed, the time required to start communication can be reduced.

  When transmitting the shortened synchronization signal, the transmission unit may increase the signal strength with respect to at least a part of the data signal multiplexed on the synchronization signal. Thus, when transmitting a shortened synchronization signal, the reception quality in the terminal apparatus can be improved by increasing the signal strength with respect to at least a part of the data signal multiplexed on the synchronization signal.

  The synchronization signal generated by the generation unit may include at least a known signal for establishing synchronization with the base station apparatus. The transmission unit may use different known signals for the shortened synchronization signal and the unreduced synchronization signal. In this case, erroneous reception of the synchronization signal can be prevented by using different known signals for the shortened synchronization signal and the unreduced synchronization signal.

  The transmission unit may repeatedly transmit the shortened synchronization signal over the transmission period of the data signal multiplexed on the shortened synchronization signal. In this case, it is possible to improve the detection probability of the synchronization signal in the terminal device by repeatedly transmitting the shortened synchronization signal over the period of the data signal multiplexed on the shortened synchronization signal.

  Another aspect of the present invention is a communication method. This communication method is a communication method for performing communication by multiplexing a plurality of terminal devices in the same time zone, and uses a synchronization signal for establishing synchronization between the base station device and the terminal device, and a synchronization signal Generating a data signal for a terminal device with which synchronization has been established, and transmitting the generated synchronization signal from the plurality of antennas when controlling the directivity of the antenna when transmitting the generated data signals from the plurality of antennas. A transmission step that does not control the directivity of the antenna. The transmission step shortens the length of the synchronization signal when a synchronization signal is transmitted and there is a data signal multiplexed to the other terminal apparatus in the same time zone as the synchronization signal.

  Another aspect of the present invention is a program for executing communication by multiplexing a plurality of terminal devices in the same time zone, and causing the computer to execute the program. This program generates a synchronization signal for establishing synchronization between a base station apparatus and a terminal apparatus, a data signal for a terminal apparatus for which synchronization is established by the synchronization signal, and a plurality of generated data signals. When transmitting from a plurality of antennas to a terminal device via a wireless network, the antenna directivity is controlled, and when transmitting generated synchronization signals from a plurality of antennas to the terminal device via a wireless network, the antenna directivity is And a transmission step that does not control sex. The transmission step shortens the length of the synchronization signal when a synchronization signal is transmitted and there is a data signal multiplexed to the other terminal apparatus in the same time zone as the synchronization signal.

  In the transmission step, when the shortened synchronization signal is transmitted to the terminal device, the terminal device may be notified that the shortened synchronization signal is transmitted prior to the transmission of the synchronization signal. In the transmission step, when the shortened synchronization signal is transmitted, the signal strength may be increased with respect to at least a part of the data signal multiplexed on the synchronization signal. Further, the synchronization signal generated by the generation step may include at least a known signal for establishing synchronization with the base station apparatus. In the transmission step, different known signals may be used for the shortened synchronization signal and the unreduced synchronization signal. In the transmission step, the shortened synchronization signal may be repeatedly transmitted over the transmission period of the data signal multiplexed on the shortened synchronization signal.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the interference with the other terminal device by the signal with respect to the terminal device before synchronization establishment can be reduced.

  Before describing the present invention in detail, an outline will be described. An embodiment of the present invention is a base station apparatus that connects a plurality of terminal apparatuses by TDMA (Time Division Multiple Access) as in the second generation cordless telephone system. One frame of the second generation cordless telephone system is composed of eight time slots, and the frames are continuously arranged. A data rate of 32 kbps is realized by allocating one time slot per frame to one terminal device. In consideration of the uplink and downlink, two time slots are assigned to one terminal device in units of frames.

  The base station apparatus according to the present embodiment also applies SDMA (Space Division Multiple Access), and assigns a plurality of terminal apparatuses to one time slot. The base station apparatus executes allocation processing according to the allocation request from the terminal apparatus. After the assignment process is completed, the base station device transmits a synchronization signal (hereinafter referred to as “synchronization burst”) for establishing synchronization with the base station device to the terminal device. However, since this transmission is a process before synchronization is established with the terminal device, the directivity cannot be adjusted, and there is a case where interference is given to signals for other terminal devices.

  In general, a synchronization burst includes a known signal called a preamble, a known signal called a unique word, information indicating a transmission source base station device, information indicating a reception destination terminal device, and a synchronization burst. Filler data for filling the transmission area and an error detection code are included. Here, the terminal device identifies the symbol timing using the preamble included in the synchronization burst, and further identifies the slot timing using the unique word. Therefore, information other than the known information is not necessarily required in the synchronization establishment process in the terminal device.

  Therefore, in the base station apparatus according to the present embodiment, when transmitting to a terminal apparatus that is not synchronized with the base station apparatus, the transmission is performed in order to reduce interference with existing terminal apparatuses. The signal length was shortened. Furthermore, with regard to the vacant resource of the part whose length has been shortened, the resource is effectively utilized by adjusting the signal strength of the signal with respect to the existing terminal device. Details will be described later.

  FIG. 1 is a diagram illustrating a configuration example of a base station apparatus 10 according to an embodiment of the present invention. The base station apparatus 10 includes a first antenna 12a, a second antenna 12b, a fourth antenna 12d, which are collectively referred to as an antenna 12, and a first radio unit 20a, a second radio unit 20b, and a fourth radio unit, which are collectively referred to as a radio unit 20. 20d, a first processing unit 22a, a second processing unit 22b, a fourth processing unit 22d, and a first modulation / demodulation unit 24a, a second modulation / demodulation unit 24b, and a fourth modulation / demodulation unit. 24d, an interface unit 26 (Interface unit; hereinafter, abbreviated as “IF unit 26”), a quality acquisition unit 28, a control unit 30, and a management unit 32. Further, as signals, a first modulation / demodulation unit collectively referred to as a first radio unit side signal 200a, a second radio unit side signal 200b, a fourth radio unit side signal 200d, and a modulation / demodulation unit side signal 202, which are collectively referred to as a radio unit side signal 200. Side signal 202a, second modulation / demodulation unit side signal 202b, and fourth modulation / demodulation unit side signal 202d.

  As a receiving operation, the antenna 12 receives a radio frequency signal from a terminal device (not shown). The antenna 12 transmits a radio frequency signal to a terminal device (not shown) as a transmission operation. Note that the timing of the reception operation and the transmission operation is controlled by the control unit 30 described later. The antenna 12 corresponds to the adaptive array antenna technology, and the directivity of the antenna is controlled by a processing unit 22 described later. Here, the number of antennas 12 is “4”, but other numbers may be used.

  As a reception operation, the radio unit 20 performs frequency conversion on a radio frequency signal received by the antenna 12 to derive a baseband signal. The radio unit 20 outputs the baseband signal as the radio unit side signal 200 to the processing unit 22. In general, baseband signals are formed by in-phase and quadrature components, so they should be transmitted by two signal lines. Here, for clarity of illustration, only one signal line is used. Shall be shown. Further, an automatic gain controller (Automatic Gain Controller; hereinafter abbreviated as “AGC”) and an analog-digital converter (Analog Digital converter; hereinafter abbreviated as “A / D converter”) are also included. As a transmission operation, the radio unit 20 performs frequency conversion on the baseband signal from the processing unit 22 and derives a radio frequency signal. Here, a baseband signal from the processing unit 22 is also shown as a radio unit side signal 200. The radio unit 20 outputs a radio frequency signal to the antenna 12. Further, a power amplifier (Power Amplifier; hereinafter abbreviated as “PA”) and a digital-analog converter (Digital Analog converter; hereinafter abbreviated as “D / A converter”) are also included.

  The processing unit 22 performs adaptive array signal processing on the plurality of radio unit side signals 200 as a reception operation after synchronization is established. The processing unit 22 outputs the result of the adaptive array signal processing as the modulation / demodulation unit side signal 202. One modulation / demodulation unit side signal 202 corresponds to a signal corresponding to one of a plurality of spatially multiplexed terminal apparatuses. The processing unit 22 performs adaptive array signal processing on the modulation / demodulation unit side signal 202 input from the modulation / demodulation unit 24 as a transmission operation. Further, the processing unit 22 outputs a signal subjected to adaptive array signal processing as a radio unit side signal 200.

  Specifically, the processing unit 22 weights and adds each of the reception signals sent from the radio unit 20 by the reception weight vector derived from the reception signal as reception processing. The method for deriving the reception weight vector may be any method, one of which is the derivation by the LMS (Least Mean Square) algorithm. Here, the added signal is shown as a modulation / demodulation unit side signal 202.

  In the second generation cordless telephone system, a preamble is arranged at the head portion of the burst signal. Since the preamble is a known signal, it corresponds to a training signal. Here, the processing unit 22 outputs a training signal stored in advance as a reference signal during the period of the training signal. In addition to these periods, the received signal is determined based on a predetermined threshold value, and the result is output as a reference signal. The determination may be a soft determination instead of a hard determination. Here, communication with the terminal device is performed in a predetermined time slot. Therefore, communication is performed using a burst signal.

  Further, as the transmission process, the processing unit 22 estimates a transmission weight vector necessary for weighting the transmission signal from the reception weight vector. The method for estimating the transmission weight vector is arbitrary, but as the simplest method, the reception weight vector may be used as it is. Alternatively, the reception weight vector may be corrected by a conventional technique in consideration of the Doppler frequency fluctuation of the propagation environment caused by the time difference between the reception process and the transmission process. Here, it is assumed that the reception weight vector is used as it is as the transmission weight vector. Further, the transmission vector is weighted by the transmission weight vector, and a preamble is added to the head portion of the resulting burst signal. In addition, the above operation | movement shall be controlled by the control part 30 of FIG. 1 as mentioned above.

  The modem unit 24 performs demodulation on the modem unit side signal 202 from the processing unit 22 as reception processing. The modem unit 24 outputs the demodulated signal to the IF unit 26. Further, the modem unit 24 performs modulation as transmission processing. The modem unit 24 outputs the modulated signal to the processing unit 22 as the modem unit side signal 202. Here, π / 4 shift QPSK (Quadrature Phase Shift Keying) corresponding to the second generation cordless telephone system may be used as the modulation method. On the other hand, the demodulation performs delay detection and synchronous detection.

  The IF unit 26 is connected to a network (not shown), and outputs a signal of each terminal device demodulated by the modem unit 24 to a network (not shown) as reception processing. In addition, when communication request information is included in any of the demodulated individual terminal device signals, the IF unit 26 notifies the control unit 30 of information indicating the terminal device related to the communication request information. Further, the IF unit 26 inputs data from the network and outputs it to the modem unit 24 as transmission processing. As described above, the antenna 12, the radio unit 20, the processing unit 22, and the modem unit 24 realize communication with a plurality of terminal devices (not shown). In order to realize communication, a plurality of time slots included in each of consecutively arranged frames is used.

  The quality acquisition unit 28 acquires the signal quality of each of the plurality of terminal devices and outputs it to the control unit 30. Here, the intensity of the signal received from each of the plurality of terminal devices is measured and used as the signal quality. Since SDMA is used as described above, the radio frequency signal and the radio unit side signal 200 include signals from a plurality of terminal devices assigned to one time slot. Therefore, the quality acquisition unit 28 may derive the signal quality based on the reception weight vectors respectively derived from the first processing unit 22a to the fourth processing unit 22d. This is because each of the reception weight vectors is calculated so as to correspond to each of the plurality of terminal devices. The quality acquisition unit 28 derives the intensity of the signal corresponding to the terminal device by integrating the components of the reception weight vector corresponding to one terminal device. When the SDMA is not executed, the quality acquisition unit 28 may derive the signal strength from the radio frequency signal or the radio unit side signal 200. Further, the quality acquisition unit 28 may acquire the downlink signal quality measured inside the terminal device via a wireless line.

  The control unit 30 receives the communication request notified from the IF unit 26 and the signal quality sent from the quality acquisition unit 28 as inputs, and allocates radio channels to a plurality of terminal devices that should communicate with the base station device 10. . In other words, the control unit 30 determines a plurality of terminal devices that should perform space division multiplexing. Moreover, the timing of the component contained in the base station apparatus 10 is controlled. In addition, after the channel assignment is completed, the control unit 30 generates and transmits a synchronization burst to be transmitted to the terminal device. In addition, the control unit 30 sends the allocation result to the management unit 32.

  In TDMA, since a time slot is allocated to a terminal device in order to communicate with the terminal device, the radio channel corresponds to a time slot. Here, since SDMA is also targeted in addition to TDMA, a plurality of radio channels are arranged in one time slot. Therefore, a plurality of terminal devices are assigned to one time slot. Note that the control unit 30 may refer to data managed by the management unit 32 when assigning time slots.

  The management unit 32 manages data related to time slot allocation based on information sent from the control unit 30. Specifically, the management unit 32 stores information for identifying the terminal device to which the time slot is assigned and information indicating the assigned time slot in a memory (not shown) in association with each other. In addition, the management unit 32 accesses the memory according to a request from the control unit 30, searches for information related to the request from the correspondence relationship, and notifies the control unit 30 of the result.

  FIG. 2 is a diagram illustrating a frame structure example realized by the control unit 30 of FIG. FIG. 2 corresponds to the case where the control unit 30 assigns time slots to a plurality of terminal devices. FIG. 2 shows the arrangement of time slots on the time axis, that is, the arrangement of radio channels in the direction of the horizontal axis, and the arrangement of radio channels on the spatial axis in the direction of the vertical axis. That is, the horizontal axis corresponds to TDMA and the vertical axis corresponds to SDMA.

  In FIG. 2, two consecutive frames are shown as “i-th frame” and “(i + 1) -th frame”. Each frame includes “first time slot” to “fourth time slot”. Here, since one of the uplink and the downlink is shown, the number of time slots included in one frame is set to “4”, but actually “8” time slots are included. Further, “fifth time slot” to “eighth time slot” (not shown) are also included. A predetermined number is assigned to the frame. “Time slot” indicates a time slot assigned to a terminal device. As described above, one time frame includes eight time slots, but each of the four time slots is assigned to the terminal device for the uplink or the downlink. Here, the first time slot, the second time slot, the third time slot, and the fourth time slot are assumed in order from the top in the frame. Therefore, even in different frames, it can be said that the first time slots have the same relative timing within the frame.

  However, an uplink time slot and a downlink time slot are generally one-to-one so that a terminal device assigned to the “first time slot” is also assigned a “fifth time slot”. It corresponds with. Therefore, only “4” time slots will be described below as illustrated.

  In FIG. 2, in order to indicate that separate terminal devices are multiplexed, a terminal device A 34 (hereinafter referred to as “user A”) and a terminal device B 36 (hereinafter referred to as “user A”) are provided in each slot in FIG. This is referred to as “User B”). In addition, such a display is performed in order to clarify description, and actually, an identification number other than these may be given to the terminal device. The control unit 30 assigns the user A to the “first time slot” of the “i-th frame” and the “(i + 1) -th frame”. In addition, the control unit 30 assigns the user B to the “first time slot” as a terminal device multiplexed with the user A.

  FIG. 3 is a diagram illustrating a configuration example of the control unit 30 of FIG. The control unit 30 includes a confirmation unit 40, a generation unit 50, and an adjustment unit 60. The confirmation unit 40 receives a link channel allocation request indicating a communication start request from a terminal device that should perform communication with the base station device 10 via the modem unit 24. In response to this reception, the confirmation unit 40 is a terminal device that has established synchronization with the base station device and is performing communication (hereinafter, referred to as “existing terminal device”). .) Is confirmed with the management unit 32, and the result is notified to the generation unit 50 and the adjustment unit 60. Further, the confirmation unit 40 represents information indicating whether or not it has a function of receiving a shortened synchronization burst signal from the terminal device via the modulation / demodulation unit 24 (hereinafter referred to as a “shortened synchronization burst flag”). ) And notify the generation unit 50. The shortened synchronization burst correspondence flag may be included in a signal related to a communication start request.

  The generation unit 50 generates a synchronization burst between the terminal device and the base station device 10 according to the result confirmed by the confirmation unit 40, and directs the generated synchronization burst toward the terminal device. To send to. Specifically, when the existence of an existing terminal device is not confirmed by the confirmation unit 40, the generation unit 50 generates a normal synchronization burst (hereinafter referred to as “normal synchronization burst”). On the other hand, when the confirmation unit 40 confirms the presence of an existing terminal device, the generation unit 50 generates a shortened synchronization burst (hereinafter referred to as a “shortened synchronization burst”). Furthermore, prior to transmission of the generated shortened synchronization burst, the generation unit 50 causes the radio unit 20 to transmit a signal indicating that the shortened synchronization burst is transmitted to the terminal device (hereinafter referred to as “preliminary notification”). ).

  4A and 4B are diagrams illustrating first and second generation examples of the synchronization burst in the generation unit 50 of FIG. 4A to 4B, the horizontal axis indicates time. Further, a period from time 0 to time t5 is defined as one slot section. FIG. 4A is a diagram illustrating a normal synchronization burst generated in the generation unit 50 of FIG. As illustrated, the normal synchronization burst includes “preamble”, “unique word”, “transmission CS-ID”, “reception PS-ID”, “filler data”, and “CRC”.

  “Preamble” is known information arranged at the head of the synchronization burst signal. The “unique word” indicates unique identification information. “Transmission CS-ID” indicates identification information for identifying the base station apparatus 10 that transmits the synchronization burst. “Reception PS-ID” indicates identification information for identifying a terminal device that is to receive a synchronization burst. In the “filler data”, information having no meaning is arranged, and usually 0 is filled. “CRC” indicates a cyclic redundancy check code for detecting an error occurring in the synchronization burst in the terminal device that has received the synchronization burst.

  FIG. 4B is a diagram illustrating the shortened synchronization burst generated in the generation unit 50 of FIG. As shown, the shortened synchronization burst includes a “preamble” and a “unique word”. In other words, the shortened synchronization burst is a signal obtained by removing “transmission CS-ID”, “reception PS-ID”, “filler data”, and “CRC” from the normal synchronization burst. Therefore, the shortened synchronization burst is a signal in which the transmission period is significantly shortened compared to the normal synchronization burst. According to such an aspect, since there is no signal in the section from time t1 to time t5, there is no interference with the existing terminal device.

  On the other hand, since the “send CS-ID” and the “reception PS-ID” are not included in the shortened synchronization burst, other terminal devices may receive errors. Therefore, when transmitting the shortened synchronization burst, the base station apparatus 10 uses a unique word different from the normal synchronization burst so that other terminal apparatuses do not receive this synchronization burst by mistake. At this time, the type of unique word included in the shortened synchronization burst may be notified in advance notification. By such an aspect, a shortened synchronization burst can be used without affecting other terminal devices.

  Returning to FIG. When the presence of an existing terminal device is confirmed by the confirmation unit 40, the adjustment unit 60 adjusts the signal strength of the signal for the existing terminal device. This will be described using a specific example. FIG. 5 is a diagram illustrating an example of adjusting the signal intensity in the adjustment unit 60 of FIG. The horizontal axis indicates time. The vertical axis indicates the signal intensity. Here, the first terminal device and the second terminal device are assumed to be existing terminal devices. Further, it is assumed that the third terminal device is a terminal device that has newly made a communication start request. Here, the signal for the first terminal apparatus includes the first preamble, the first unique word, the first data, and the first CRC. Similarly, the signal for the second terminal device includes the second preamble, the second unique word, the second data, and the second CRC. Also, the synchronization burst for the third terminal device includes a third preamble and a third unique word.

  The adjustment example shown in the drawing includes a preamble area 300, a unique word area 310, a data area 320, and a CRC area 330. The preamble region 300 includes a first preamble to a third preamble. The unique word region 310 includes a first unique word to a third unique word. The data area 320 includes first data to second data. The CRC area 330 includes a first CRC and a second CRC.

  The signal strengths of the first to third preambles arranged in the preamble area 300 and the first to third unique words arranged in the unique word area 310 are set to P, respectively. On the other hand, the signal strengths of the first and second data arranged in the data area 320 and the first and second CRC arranged in the CRC area 330 are respectively set to 1.5P.

  As described above, by shortening the synchronization burst, it is possible to increase the signal strength of the shortened portion from the time t1 to the time t5 in the transmission signal for the existing terminal device. With this increase, the reception performance in the existing terminal device can be improved, and thus system resources can be effectively utilized. Note that the sum of the signal strengths of the transmission signals in the base station device 10 does not exceed 3P at any time, so that the increase in signal strength does not affect the base station device 10 and the entire system.

  As shown in FIG. 5, since the preamble area 300 and the unique word area 310 are arranged in both the normal synchronization burst and the shortened synchronization burst, interference may occur in this portion. However, since the preamble area 300 and the unique word area 310 are corrected by applying error correction, there is almost no influence on the existing terminal apparatus. In other words, since the amount of interference in the existing terminal device can be reduced by using the shortened synchronization burst, the effect of error correction decoding can be improved.

  These configurations can be realized in terms of hardware by a CPU, memory, or other LSI of an arbitrary computer, and in terms of software, they are realized by a program having a communication function loaded in the memory. The functional block realized by those cooperation is drawn. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  Here, the operation example of the base station apparatus 10 of FIG. 1 is demonstrated in detail. FIG. 6 is a diagram illustrating an operation example of the base station apparatus 10 of FIG.

  The base station apparatus 10 receives a link channel establishment request signal for a communication start request from the terminal apparatus (S10). In response to the reception of this signal, the base station apparatus 10 transmits a link channel assignment signal (S12). Next, the base station apparatus 10 checks the shortened synchronization burst correspondence flag included in the signal received in S10 (S14). Here, when the shortened synchronization burst support flag indicates that support is possible (Y in S14), the base station device 10 confirms the presence of the existing terminal device (S16).

  When the presence of an existing terminal device is confirmed (Y in S16), the base station device 10 performs advance notification to the terminal device (S18). Next, the base station apparatus 10 generates a shortened synchronization burst (S20). Further, the base station apparatus 10 transmits the generated shortened synchronization burst to the terminal apparatus (S22). Furthermore, the base station apparatus 10 adjusts the signal power of the signal included in the signal from the existing terminal apparatus to the beginning of the next time slot after the transmission of the shortened synchronization burst is completed (S24).

  On the other hand, if the shortened synchronization burst support flag indicates that the response is not possible (N in S14), or if the presence of the existing terminal device is not confirmed (N in S16), the base station device 10 performs the normal synchronization burst. Generate (S26), and transmit the generated normal synchronization burst to the terminal device (S28).

  According to the embodiment of the present invention, when the presence of an existing terminal device is confirmed, the signal generated by the generation unit 50 is shortened and transmitted to the terminal device, so that the signal is transmitted in the shortened time zone. Since it is not transmitted, the interference with the existing terminal device can be reduced. In addition, by transmitting a signal indicating that the shortened signal is transmitted to the terminal device prior to transmission of the shortened signal, synchronization processing can be performed without delay in the terminal device. Can be reduced. Further, after transmitting the shortened signal, by increasing the strength of the signal to be transmitted to the existing terminal device whose existence has been confirmed by the confirmation unit 40, it is possible to effectively use unused resources. Further, by using the shortened synchronization burst, the portion that can interfere with the existing terminal device can be reduced, so that the effect of error correction decoding can be improved and the reception quality of the existing terminal device can be improved.

  Next, the modification of embodiment of this invention is shown. First, an overview. The modification of embodiment of this invention is related with the base station apparatus 10 similarly to embodiment. The base station apparatus 10 in this modification has the same configuration as the base station apparatus 10 shown in FIGS. The difference from the embodiment of the present invention is the mode of the shortened synchronization burst generated by the generation unit 50 included in the control unit 30. In addition, about the part which is common in embodiment mentioned above, the same code | symbol is attached | subjected and description is simplified.

  FIG. 7 is a diagram illustrating a generation example in the generation unit 50 according to the modification of the embodiment of the present invention. As illustrated, the generation unit 50 generates a shortened synchronization burst including “preamble”, “unique word”, “transmission CS-ID”, “reception CS-ID”, and “CRC”. The shortened synchronization burst in this modification is a signal obtained by removing “filler data” from the normal synchronization burst. Further, the shortened synchronization burst in this modification includes “transmission CS-ID”, “reception CS-ID”, and “CRC” as compared with the shortened synchronization burst in FIG. 4B shown in the above-described embodiment. Is different.

  Thus, by including “transmission CS-ID” and “reception CS-ID” in the shortened synchronization burst, processing in the terminal device can be reduced. By including “CRC” in the shortened synchronization burst, the terminal device can check whether there is an error in the shortened synchronization burst and reduce the time required for establishing synchronization. Moreover, the erroneous transmission in the existing terminal device can be prevented by “transmission CS-ID” and “reception CS-ID”. In such a case, it is not necessary to change the unique word between the normal synchronization burst and the shortened synchronization burst.

  Next, another modification of the embodiment of the present invention will be shown. First, an overview. The modification of embodiment of this invention is related with the base station apparatus 10 similarly to embodiment. The base station apparatus 10 in this modification has the same configuration as the base station apparatus 10 shown in FIGS. The difference from the embodiment of the present invention is that the communication method applied between the base station apparatus 10 and the terminal apparatus is not OFDMA (Orthogonal Frequency Division Multiple Access) but OFDMA. In addition, about the part which is common in embodiment mentioned above, the same code | symbol is attached | subjected and description is simplified.

  FIG. 8 is a diagram illustrating a generation example in the generation unit 50 according to another modification of the embodiment of the present invention. The horizontal axis indicates time. The vertical axis indicates the frequency. Here, it is assumed that the first terminal device, the second terminal device, and the fourth terminal device are existing terminal devices. Further, it is assumed that the third terminal device is a terminal device that has newly made a communication start request. It is assumed that the first terminal device to the fourth terminal device are assigned to each of the first subchannel 400a to the fourth subchannel 400d represented by the subchannel 400. For convenience of explanation, each subchannel 400 is shown continuously, but a guard channel may be included between the subchannels 400. Each subchannel 400 may be composed of a plurality of subcarriers.

  Here, the signals for the first terminal device, the second terminal device, and the fourth terminal device are respectively the first preamble, the second preamble, and the fourth preamble, the first unique word, the second unique word, and , Fourth unique word, first transmission CS-ID, second transmission CS-ID, and fourth transmission CS-ID, first reception PS-ID, second reception PS-ID, and fourth reception The PS-ID, the first data, the second data, and the fourth data, and the first CRC, the second CRC, and the fourth CRC are included. Further, since the synchronization burst for the third terminal device is generated as a shortened synchronization burst by the generation unit 50, it includes only the third preamble and the third unique word. For convenience, the information included in the signal for each terminal apparatus is illustrated as being arranged in the frequency band to which each terminal apparatus is allocated, but is arranged in at least one or more subcarriers included in each frequency band. It may be.

  The generation example shown in the figure includes a preamble area 300, a unique word area 310, a transmission CS-ID area 340, a reception PS-ID area 350, a data area 320, and a CRC area 330. The preamble area 300 includes a first preamble to a fourth preamble. The unique word area 310 includes first to fourth unique words. The transmission CS-ID area 340 includes a first transmission CS-ID, a second transmission CS-ID, and a fourth transmission CS-ID. The reception PS-ID area 350 includes a first reception PS-ID, a second reception PS-ID, and a fourth reception PS-ID. The data area 320 includes first data, second data, and fourth data. The CRC area 330 includes a first CRC, a second CRC, and a fourth CRC.

  As shown in the figure, in the third terminal device that newly requested the start of communication, by shortening the synchronization burst, there is no signal in the section from time t1 to time t5. Interference can be reduced. Note that the shortened synchronization burst may include a transmission CS-ID and a reception PS-ID.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and various modifications can be made to the combination of each component and each processing process, and the embodiment and the modification can be combined, or the modifications can be combined. Those skilled in the art will understand that such modifications and combinations are also within the scope of the present invention.

  In the embodiment of the present invention, the base station device 10 has been described as transmitting a normal synchronization burst when the presence of an existing terminal device is not confirmed. However, the present invention is not limited to this. For example, in the case where the terminal device indicated by Y in S14 corresponds to the shortened synchronization burst in FIG. 6, the processing in S16 is omitted, and the base station regardless of the presence or absence of the existing terminal device. The station apparatus 10 may generate and transmit a shortened synchronization burst. In this case, the process of S22 may be omitted. According to this aspect, the process in the base station apparatus 10 can be simplified. Further, the transmission unit has been described as transmitting a preamble and a unique word as a shortened synchronization burst. However, the present invention is not limited to this. For example, the transmission unit may repeatedly transmit the shortened synchronization signal in the section from time t1 to time t5 in FIG. In this case, since the transmission energy of the synchronization burst can be increased, the detection probability of the synchronization burst in the terminal device can be improved, and the synchronization establishment process can be completed earlier.

  Further, the access scheme in the embodiment of the present invention has been described as applying the space division multiple access scheme as shown in FIG. However, the present invention is not limited to this, and other access methods that multiplex a plurality of terminal devices in the same time zone, for example, frequency division multiple access method (Code Division Multiple Access) and code division multiple access method (Code Division Multiple Access) are applied. May be. Even in such a case, the same effect as described above can be obtained.

It is a figure which shows the structural example of the base station apparatus which concerns on the Example of this invention. It is a figure which shows the structural example of the flame | frame implement | achieved by the control part of FIG. It is a figure which shows the structural example of the control part of FIG. FIGS. 4A and 4B are diagrams illustrating first and second generation examples of the synchronization burst in the generation unit of FIG. It is a figure which shows the example of adjustment of the signal strength in the adjustment part of FIG. It is a figure which shows the operation example of the base station apparatus of FIG. It is a figure which shows the example of a production | generation in the production | generation part concerning the modification of embodiment of this invention. It is a figure which shows the production | generation example in the production | generation part concerning another modification of embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Base station apparatus, 12 Antenna, 20 Radio | wireless part, 22 Processing part, 24 Modulation / demodulation part, 26 IF part, 28 Quality acquisition part, 30 Control part, 32 Management part, 40 Confirmation part, 50 Generation part, 60 Adjustment part, 200 Radio section side signal, 202 Modulation / demodulation section side signal, 300 Preamble area, 310 Unique word area, 320 Data area, 330 CRC area, 340 Transmission CS-ID area, 350 Reception PS-ID area, 400 Subchannels

Claims (7)

A base station device that performs communication by multiplexing a plurality of terminal devices in the same time zone,
A generation unit that generates a synchronization signal for establishing synchronization between the base station device and the terminal device, and a data signal for the terminal device that has established synchronization by the synchronization signal;
When transmitting the data signal generated by the generation unit from a plurality of antennas, the directivity of the antenna is controlled, and when transmitting the synchronization signal generated by the generation unit from the plurality of antennas, the antenna directivity is controlled. A transmitter that does not control
With
When transmitting the synchronization signal, the transmission unit shortens the length of the synchronization signal when there is a data signal multiplexed to the other terminal apparatus in the same time zone as the synchronization signal. A base station apparatus.   The transmission unit, when transmitting a shortened synchronization signal to a terminal device, notifies the terminal device that the shortened synchronization signal is transmitted prior to transmission of the synchronization signal. The base station apparatus according to 1.   The base station according to claim 1, wherein, when transmitting the shortened synchronization signal, the transmission unit increases the signal strength with respect to at least a part of the data signal multiplexed on the synchronization signal. apparatus. The synchronization signal generated by the generation unit includes at least a known signal for establishing synchronization with the base station device,
The base station apparatus according to claim 1, wherein the transmitting unit uses different known signals for the shortened synchronization signal and the unreduced synchronization signal.   The base station apparatus according to claim 1, wherein the transmission unit repeatedly transmits the shortened synchronization signal over a transmission period of the data signal multiplexed on the shortened synchronization signal. A communication method for performing communication by multiplexing a plurality of terminal devices in the same time zone,
Generating a synchronization signal for establishing synchronization between the base station device and the terminal device, and a data signal for the terminal device having established synchronization by the synchronization signal;
When transmitting the generated data signal from a plurality of antennas, the antenna directivity is controlled, and when transmitting the generated synchronization signal from the plurality of antennas, a transmission step that does not control the antenna directivity;
Including
The transmission step shortens the length of the synchronization signal when a synchronization signal is transmitted and there is a data signal multiplexed to the other terminal device in the same time zone as the synchronization signal. A communication method characterized by the above. A program for executing communication by multiplexing a plurality of terminal devices in the same time zone,
Generating a synchronization signal for establishing synchronization between the base station device and the terminal device, and a data signal for the terminal device having established synchronization by the synchronization signal;
When transmitting the generated data signal from multiple antennas to the terminal device via the wireless network, the antenna directivity is controlled and the generated synchronization signal is transmitted from the multiple antennas to the terminal device via the wireless network. A transmission step that does not control the directivity of the antenna,
Including
The transmission step shortens the length of the synchronization signal when a synchronization signal is transmitted and there is a data signal multiplexed to the other terminal device in the same time zone as the synchronization signal. A program for causing a computer to execute.

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