JP2009065509A - Random access signal designation method and communication method, and base station device employing them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that it is desired to reduce the effect of unbalancing in communication quality of unicast and broadcast. <P>SOLUTION: A control unit 26 generates at least two control signals, for designating a burst causing a terminal device to transmit a random access signal, in one downlink sub-frame. A baseband processing unit 24 or the like transmits the at least two control signals while assigning them to mutually different bursts of the downlkink sub-frame. The baseband processing unit 24 or the like receives the random access signal from the terminal device in the burst, designated to the at least two control signals, respectively, in an uplink sub-frame in one-to-one correspondence to the burst to which the control signals are assigned. In a corresponding combination of the burst to which the control signals are assigned, and the burst to which the random access signal is assigned, directivity of an antenna is controlled in common. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication technique, and more particularly to a random access signal designation method and a communication method for connecting a terminal apparatus, and a base station apparatus using them.

One of the wireless communication systems is a wireless MAN (Metropolitan Area Network) system standardized by the IEEE 802.16 standard and the IEEE 802.16e standard (hereinafter collectively referred to as “IEEE802.16 standard”). As physical layers in the IEEE 802.16 standard, SC (Single Carrier), OFDM (Orthogonal Frequency Division Multiplexing), and OFDMA (Orthogonal Frequency Division Multiple Access) are defined. For example, combining TDMA and TDD for OFDMA is being considered. The basic frame in such a case includes a downlink subframe, a TTG (Transmit / Receive Transmission Gap), an uplink subframe, and an RTG (Receive / Transmit Transmission Gap) (see, for example, Non-Patent Document 1).
Toshikazu Kaname, “IEEE 802.16 Standard: 802.16-2004 (Fixed WiMAX) and 802.16e (Mobile WiMAX)”, Wireless Broadband Textbook / High Speed IP Wireless Edition, Japan, Impress R & D, June 21, 2006 , P. 159-212

  A signal for establishing data communication (hereinafter referred to as “control signal”) is arranged at the head portion of the downlink subframe. The control signal includes FCH (Frame Control Header), DL-MAP (Downlink MAP Message), and UL-MAP (Uplink MAP Message), which will be described in detail later. Before the communication between the base station apparatus and the terminal apparatus is started, the terminal apparatus transmits a signal that triggers the start of communication, for example, a ranging request signal, based on a control signal broadcast from the base station apparatus. . Such processing is similarly performed during handover. On the other hand, during communication between the base station apparatus and the terminal apparatus, the terminal apparatus grasps the allocation status of the data signal to itself based on the control signal notified from the base station apparatus. Therefore, it can be said that the control signal is important information not only for starting communication but also for maintaining communication.

  While the base station device and the terminal device are communicating, the base station device assigns bursts to the terminal device. That is, the base station apparatus and the terminal apparatus perform unicast communication using bursts. When unicast is performed, the base station apparatus can control the antenna directivity so as to be suitable for the terminal apparatus, so that the reception characteristics in the terminal apparatus can be improved. However, when broadcasting is performed as in the case of a control signal, the base station apparatus should direct antenna directivity to a plurality of terminal apparatuses, and thus cannot control the antenna directivity. As a result, even if the reception characteristic in communication is improved, the reception characteristic of the control signal, which is information more important than the communication, is not improved. Thus, if there is an imbalance in communication quality between unicast and broadcast, the reception characteristics of the communication system are limited by the reception characteristics of the broadcast regardless of the improvement of the reception characteristics of unicast.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a communication technique that reduces the influence of an imbalance in communication quality between unicast and broadcast.

  In order to solve the above problems, a base station apparatus according to an aspect of the present invention defines a frame formed by a downlink subframe including a plurality of bursts and an uplink subframe including a plurality of bursts. A base station apparatus that generates at least two control signals in one downlink subframe for designating a burst for transmitting a random access signal to a terminal apparatus, and at least two controls generated by the generation section A burst that is specified by each of a transmitter that transmits signals while allocating them to different bursts in a downlink subframe, and at least two control signals transmitted from the transmitter, and each control signal is assigned to a burst. In bursts in uplink subframes that are correlated one-to-one, random addresses from terminal devices Comprising a receiver for receiving a Seth signal, and a control section for controlling the operations of the receiver and transmitter. The control unit makes the antenna directivity control common in the corresponding combinations of the burst to which the control signal is assigned and the burst to which the random access signal is assigned.

  According to this aspect, a plurality of combinations corresponding to the control signal and the random access signal are generated, and the antenna directivity control is made common in each combination. it can.

  The transmission unit may arrange the bursts to which the control signals are allocated in the downlink subframe so as to be symmetrical with the arrangement of the bursts to which the random access signals are allocated in the uplink subframe. In this case, since the burst arrangement for the control signal and the random access signal is made common, it is possible to omit transmission of information relating to the allocation of the random access signal.

  You may further provide the measurement part which measures a propagation environment. The transmission unit may determine the arrangement of bursts to which each control signal is assigned according to the measurement result of the measurement unit. In this case, since each control signal is assigned according to the propagation environment, each control signal can be assigned so as to be suitable for the propagation environment.

  The transmission unit also arranges the control signal in the burst at the beginning of the downlink subframe, and other than the control signal arranged in the burst at the beginning of the downlink subframe depending on the reception status of the random access signal in the reception unit. The transmission frequency of the control signal may be adjusted. In this case, since the transmission frequency of the control signal is adjusted according to the reception status of the random access signal, it is possible to suppress a decrease in transmission efficiency.

  Another aspect of the present invention is also a base station apparatus. This apparatus is a base station apparatus that defines a frame including a plurality of bursts, a generation unit that generates a first control signal and a plurality of second control signals, and a first unit that is generated by the generation unit A transmission unit that arranges the control signal in a burst at the head portion of the frame and transmits a plurality of second control signals in different bursts. The generation unit includes at least part of the information of the first control signal in each of the plurality of second control signals.

  According to this aspect, since at least part of the information of the first control signal is included in each of the plurality of second control signals, the broadcast quality is determined by the presence of the first control signal and the plurality of second control signals. Can be improved.

  Yet another aspect of the present invention is also a base station apparatus. This apparatus is a base station apparatus that repeatedly defines a frame including a plurality of bursts, a generation unit that generates a first control signal and a plurality of second control signals, and a first unit generated by the generation unit And a transmission unit for transmitting the second control signal while arranging the second control signals in different bursts. The generation unit includes information on a frame in which the first control signal is arranged in the first control signal, and information on a frame subsequent to the frame in which the first control signal is arranged in the plurality of second control signals. Include in each.

  According to this aspect, since information on a frame subsequent to the frame in which the first control signal is arranged is included in each of the plurality of second control signals, the freedom of arrangement of bursts assigned to the plurality of second control signals The degree can be improved.

  You may further provide the control part which controls operation | movement of a transmission part. The control unit may perform different antenna directivity control for each of the plurality of second control signals. In this case, since the antenna directivity control for each of the plurality of second control signals is made different, the quality of the broadcast can be improved.

  Yet another aspect of the present invention is a method for specifying a random access signal. In this method, a frame formed by a downlink subframe including a plurality of bursts and an uplink subframe including a plurality of bursts is defined, and a burst for transmitting a random access signal to a terminal device is specified. Generating at least two control signals in one downlink subframe, transmitting at least two generated control signals while assigning them to different bursts in the downlink subframe, and at least two transmitted signals. Receiving a random access signal from a terminal device in a burst specified in each of the control signals and in a burst in an uplink subframe corresponding to the burst to which each control signal is assigned on a one-to-one basis; Is provided. In the transmitting step and the receiving step, antenna directivity control is made common in a corresponding combination of a burst to which a control signal is assigned and a burst to which a random access signal is assigned.

  Yet another embodiment of the present invention is a communication method. In this method, a step of generating a first control signal and a plurality of second control signals and a frame including a plurality of bursts are defined, and the generated first control signal is applied to a head portion of the frame. Arranging in a burst and transmitting a plurality of second control signals while arranging them in different bursts. The generating step includes at least part of the information of the first control signal in each of the plurality of second control signals.

  Yet another embodiment of the present invention is also a communication method. In this method, a step of generating a first control signal and a plurality of second control signals and a frame including a plurality of bursts are repeatedly specified, and the generated first control signal is used as a head portion of the frame. And transmitting a plurality of second control signals while arranging them in different bursts. In the generating step, information on a frame in which the first control signal is arranged is included in the first control signal, and information on a frame subsequent to the frame in which the first control signal is arranged is included in the plurality of second controls. Include in each of the signals.

  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.

  According to the present invention, it is possible to reduce the influence of imbalance in communication quality between unicast and broadcast.

  Before describing the present invention in detail, an outline will be described. An embodiment of the present invention relates to a communication system that performs TDMA in the time direction while performing OFDMA in the frequency direction as in the IEEE 802.16 standard. The base station apparatus defines a frame based on the downlink subframe and the uplink subframe, arranges a control signal at the head portion of the downlink subframe, and arranges a ranging area in the uplink subframe. When receiving the control signal notified from the base station apparatus, the terminal apparatus acquires parameters. In addition, the terminal device transmits a ranging request as a random access signal in the ranging area while using the acquired parameter. Thereafter, processing for network entry is performed between the base station device and the terminal device, and both perform communication. On the other hand, since a terminal device that cannot receive a control signal broadcast from the base station device cannot transmit a ranging request, it cannot communicate with the base station device. In order to cope with this, the base station apparatus according to the present embodiment executes the following processing.

  The base station apparatus generates a signal including at least a part of the information included in the control signal (hereinafter referred to as “D signal”). The base station apparatus transmits a plurality of D signals while changing the antenna directivity in the downlink subframe. On the other hand, the base station apparatus arranges bursts for each of a plurality of random access signals (hereinafter referred to as “R signals”) in the uplink subframe so as to be symmetrical to the arrangement of bursts assigned to the D signal in the downlink subframe. To do. Here, the function of the R signal is the same as the ranging request. Further, the base station apparatus makes the antenna directivity common to the corresponding D signal and R signal. The terminal signal has a possibility of receiving any D signal even if it cannot receive the control signal. For example, a D signal transmitted with antenna directivity in the direction in which the terminal device exists is easily received by the terminal device. The terminal device transmits the R signal in a burst corresponding to the received D signal. Since the antenna directivity is common between the burst of the D signal and the burst of the R signal, the R signal transmitted from the terminal apparatus is easily received by the base station apparatus.

  FIG. 1 shows a configuration of a communication system 100 according to an embodiment of the present invention. The communication system 100 includes a first terminal device 12a and a second terminal device 12b collectively referred to as a base station device 10 and a terminal device 12. Here, one base station apparatus 10 and two terminal apparatuses 12 are shown, but the number of base station apparatuses 10 and terminal apparatuses 12 is not limited to this.

  The base station apparatus 10 defines a frame formed by a downlink subframe including a plurality of bursts and an uplink subframe including a plurality of bursts. Although details of the frame configuration will be described later, the frames are repeatedly arranged. The base station apparatus 10 communicates with the terminal apparatus 12 by assigning the bursts included in the downlink subframe and the uplink subframe to the terminal apparatus 12. Here, the operation for assigning a burst to a new terminal device 12 is called network entry processing.

  When a plurality of base station devices 10 (not shown) are installed, the terminal device 12 executes a handover process with the plurality of base station devices 10. The operation for the handover destination base station apparatus 10 to assign a burst to a new terminal apparatus 12 is also called network entry processing. Although the base station apparatus 10 may include a plurality of antennas, only one antenna is described here for the sake of simplicity. The terminal device 12 communicates with the base station device 10 in bursts assigned by the base station device 10.

  2A to 2B show frame formats in a communication system to be compared with the communication system 100. FIG. In FIG. 2A, the vertical axis corresponds to frequency, and the horizontal axis corresponds to time. As described above, since OFDMA is used, the frequency on the vertical axis corresponds to the subcarrier. As shown in FIG. 2A, one frame is formed by a downlink subframe, a TTG, an uplink subframe, and an RTG. The downlink subframe is started by a preamble, that is, a known signal. Following the preamble, the FCH is arranged. The FCH includes DLFP (Downlink Frame Prefix), DL-MAP MCS (Modulation and Coding Scheme) level, and DL-MAP length as profile information.

  The DL-MAP includes map information such as position information and modulation scheme of each downlink burst included in the downlink subframe. Here, the burst is a data area specified by a combination of frequency and time, and is a unit of band allocated to the terminal device 12 or the like. Therefore, the position information of the downlink burst is indicated by a combination of frequency and time. Also, UL-MAP includes map information such as position information and modulation scheme of each uplink burst included in the uplink subframe. Following these, the downlink subframe includes a plurality of downlink bursts. The arrangement of the plurality of downlink bursts is in accordance with DL-MAP.

  Each downlink burst is assigned to the terminal device 12, and unicast communication from the base station device 10 to the terminal device 12 is realized. In addition, a control signal such as broadcast information may be assigned to the downlink burst. In that case, broadcast communication from the base station apparatus 10 is realized in the downlink burst. Similarly to the downlink subframe, the uplink subframe includes a plurality of uplink bursts. In addition, a ranging area is arranged, and the terminal apparatus 12 transmits a ranging request to the base station apparatus 10 in the ranging area.

  FIG. 2 (b) shows the structure of the frame as in FIG. 2 (a). Here, the configuration of a frame when the base station apparatus 10 corresponds to AAS (Adaptive Array Antenna System) is shown. In AAS, a plurality of physically separated antennas are fed with transmission signals weighted by phase and amplitude, respectively, so that transmitted waves radiated from the antennas are spatially combined on the radiation surface in a specific direction. A strong electric field distribution and a weak electric field are formed. In the AAS region in the downlink subframe and the uplink subframe in FIG. 2B, the base station apparatus 10 performs AAS. A plurality of downlink bursts and a plurality of uplink bursts are also arranged in the AAS area.

  FIG. 2B includes a main map and a sub map. The main map corresponds to map information about downlink bursts and uplink bursts to which AAS is not applied, and the sub map corresponds to map information about downlink bursts and uplink bursts to which AAS is applied. Further, channel information is included in the uplink subframe. The channel information is information related to the wireless transmission path characteristics measured by the terminal device 12 and is used when AAS is executed in the base station device 10. In the following description, in order to improve the communication quality of unicast communication, it is assumed that AAS is applied. However, for simplification of description, the frame configuration shown in FIG.

  FIG. 3 is a sequence diagram showing a network entry procedure in the communication system 100. First, parameter acquisition processing is performed on the downlink and uplink. The base station apparatus 10 broadcasts DL MAP and DCD (Downlink Channel Descriptor) (S10). The DCD is a MAC message that defines physical layer characteristics of the downlink sink, and stores physical layer profile information supported by the base station apparatus 10. Such DCD is periodically broadcast from the base station apparatus 10. Moreover, the base station apparatus 10 broadcasts UL MAP and UCD (Uplink Channel Descriptor) (S12). UCD is defined in the same way as DCD.

  Next, an initial ranging process is performed. The terminal device 12 transmits an RNG-REQ (Ranging Request) to the base station device 10 (S14). Here, the RNG-REQ is transmitted in the ranging area shown in FIGS. The base station apparatus 10 transmits an RNG-RSP (Ranging Response) to the terminal apparatus 12 (S16). By such an initial ranging process, the transmission timing of the terminal device 12 and the transmission power are adjusted. In addition, since a well-known technique should just be used as a process for adjusting transmission timing and transmission power, description is abbreviate | omitted here. Next, basic function confirmation processing is performed. The terminal device 12 transmits SBC-REQ (SS Basic Capability Request) to the base station device 10 (S18). The base station device 10 transmits an SBC-RSP (SS Basic Capability Response) to the terminal device 12 (S20).

  Next, terminal authentication and key exchange processing are performed. The terminal device 12 transmits a PKM-REQ (Privacy Key Management Request) to the base station device 10 (S22). The base station apparatus 10 transmits a PKM-RSP (Privacy Key Management Response) to the terminal apparatus 12 (S24). Next, registration processing is performed. The terminal device 12 transmits REG-REQ (Registration Request) to the base station device 10 (S26). The base station device 10 transmits a REG-RSP (Registration Response) to the terminal device 12 (S28). Next, IP setting processing is performed. The base station apparatus 10 and the terminal apparatus 12 exchange information regarding IP (Internet Protocol) settings (S30). After the time information setting and the additional function parameter acquisition are performed, the base station device 10 and the terminal device 12 execute data communication (S32).

  FIG. 4 shows the configuration of the base station apparatus 10. The base station apparatus 10 includes a first antenna 20a, a second antenna 20b, an Nth antenna 20n, which are collectively referred to as an antenna 20, a first RF unit 22a, a second RF unit 22b, an NRF unit 22n, which are collectively referred to as an RF unit 22, and a base. A band processing unit 24 and a control unit 26 are included.

  The RF unit 22 receives a radio frequency band signal from the terminal device 12 (not shown) via the antenna 20 as a reception operation. Here, the signal in the radio frequency band is an OFDM signal, that is, a multicarrier signal. The RF unit 22 generates a baseband signal by performing frequency conversion and quadrature detection on the radio frequency band signal, and outputs the baseband signal to the baseband processing unit 24. In general, the baseband signal is formed by the in-phase component and the quadrature component, so it should be indicated by two signal lines, but for the sake of clarity, the baseband signal is represented here. Indicated by one signal line. The RF unit 22 includes an LNA (Low Noise Amplifier) and an AD (Analog-Digital) converter (not shown).

  The RF unit 22 receives a baseband signal from the baseband processing unit 24 as a transmission operation. Here, the baseband signal is also an OFDM signal, that is, a multicarrier signal. The RF unit 22 generates a radio frequency band signal by performing orthogonal modulation and frequency conversion on the baseband signal, and outputs the radio frequency band signal to the antenna 20. The RF unit 22 includes a PA (Power Amplifier) and a DA (Digital-Analog) converter (not shown).

  The baseband processing unit 24 inputs baseband OFDM signals from the plurality of RF units 22 as a reception operation. Since the baseband OFDM signal is a time domain signal, the baseband processing unit 24 converts the time domain signal into the frequency domain by FFT (Fast Fourier Transform). In addition, the baseband processing unit 24 performs adaptive array signal processing on the frequency domain signals in units of terminal devices 12 (not shown), that is, in uplink burst units. When the uplink burst is composed of a plurality of subcarriers, the baseband processing unit 24 may perform adaptive array signal processing in units of subcarriers. It should be noted that since a known technique may be used as adaptive array signal processing, a detailed description is omitted here, but the baseband processing unit 24 derives a weight vector, and the adaptive array is based on the weight vector. Perform signal processing. The baseband processing unit 24 demodulates the OFDM signal that has been subjected to adaptive array signal processing. Here, demodulation is performed in units of subcarriers. The baseband processing unit 24 outputs the demodulated signal to a network or the like (not shown).

  In addition, as a transmission operation, the baseband processing unit 24 receives data from a network (not shown) and modulates the data to generate a frequency domain OFDM signal. The baseband processing unit 24 performs dispersion processing using weight vectors, that is, antenna directivity control, on the frequency domain OFDM signal. In addition, the baseband processing unit 24 performs an IFFT (Inverse Fast Fourier Transform) on the frequency-domain OFDM signal, thereby converting the frequency-domain signal into the time domain. Further, the baseband processing unit 24 outputs the time domain OFDM signal to the RF unit 22. The above description is processing in a burst to which AAS is applied, and description of processing in a burst to which AAS is not applied will be described later.

  The control unit 26 controls processing of the RF unit 22 and the baseband processing unit 24. The control unit 26 defines a frame in the communication system 100. FIGS. 5A to 5B show frame formats in the base station apparatus 10. FIG. 5A is shown in the same manner as FIGS. 2A to 2B, and a preamble, FCH, DL MAP, and UL MAP are arranged at the beginning of the downlink subframe. Subsequent to these, a plurality of downlink bursts are arranged, but the description is omitted in FIG.

  The control unit 26 generates FCH, DL MAP, UL MAP, and other broadcast signals. As described above, these pieces of information are collectively referred to as control signals. In addition, the control unit 26 generates a plurality of D signals indicated by “D1” to “DM”. Here, each of the plurality of D signals is formed with the same content, and the control unit 26 includes at least a part of information of the control signal, for example, information on UL MAP, in each of the plurality of D signals. The control unit 26 arranges the control signal in the burst at the beginning of the downlink subframe, and arranges the plurality of D signals in different bursts in the downlink subframe. More specifically, in the downlink subframe of FIG. 5A, a plurality of D signals are arranged in predetermined subcarriers or bursts while being shifted in time. In order to enable AAS, a preamble is arranged at the head of each D signal.

  In addition, the control unit 26 defines bursts for receiving a plurality of R signals indicated as “R1” to “RM” in the uplink subframe. Here, each of the plurality of R signals is transmitted from a terminal device 12 (not shown), and can be said to be a signal similar to RNG-REQ for requesting ranging. Therefore, the R signal is a random access signal. Although not shown in FIG. 5A, a ranging area may be provided separately in the uplink subframe. Here, the bursts assigned to each D signal and the bursts assigned to each R signal are associated one-to-one. Specifically, the burst to which the D1 signal is assigned is associated with the burst to which the R1 signal is assigned. Here, it is assumed that a rule that the terminal device 12 that has received the D signal transmits a corresponding R signal is defined. For example, the terminal device 12 that has received the D1 signal transmits the R1 signal. That is, the control unit 26 arranges the bursts assigned with each D signal in the downlink subframe so that it is symmetrical with the arrangement of the bursts assigned with each R signal in the uplink subframe.

  Considering the above, it can be said that the D signal is a signal for designating a burst for transmitting the R signal to the terminal device 12. It can also be said that the R signal is arranged in a burst designated by each of the plurality of D signals. After arranging a plurality of D signals in this way, the control unit 26 instructs the baseband processing unit 24 to generate different antenna directivities for each D signal. FIGS. 6A to 6C show antenna directivities generated in the control unit 26, which correspond to antenna directivity characteristics in a horizontal plane. In FIG. 6A, the maximum portion of the antenna gain is directed in the direction of “P1”, and in FIGS. 6B and 6C, the maximum portion of the antenna gain is directed in the directions of “P2” and “P3”. It is suitable. Returning to FIG. Thus, “dithering” is a technique for generating a plurality of types of antenna directivities so that the direction of the maximum portion of the antenna gain is different. The control unit 26 implements different antenna directivities for each D signal by applying dithering to a plurality of D signals. Specifically, the baseband processing unit 24 multiplies each D signal by a weight vector that realizes dithering.

  Further, the control unit 26 makes the antenna directivity control common to the corresponding combinations of the bursts assigned the D signal and the bursts assigned the R signal. For example, the control unit 26 shares the antenna directivity when transmitting the D1 signal and the antenna directivity when receiving the R1 signal. In a present Example, the base station apparatus 10 may receive RGN-REQ in a ranging area | region, and may receive RGN-REQ in an R signal. Even in the latter case, the subsequent processing may be the same as that shown in FIG.

  The frame shown in FIG. 5B is formed in the same manner as in FIG. In FIG.5 (b), several D signal and several R signal are arrange | positioned so that a frequency may differ. The rest of the configuration is the same as that shown in FIG. Returning to FIG. When the network entry ends, the control unit 26 allocates a predetermined burst to the terminal device 12. As described above, the control unit 26 includes information on the allocated burst in the DL-MAP and the UL-MAP. On the other hand, the control unit 26 includes the future DL MAP and UL MAP in the burst allocated to the terminal device 12 for the terminal device 12 that has received the RNG-REQ by the R signal instead of the ranging area. May be.

  This configuration can be realized in terms of hardware by a CPU, memory, or other LSI of any computer, and in terms of software, it is realized by a program having a communication function loaded in the memory. Describes functional blocks realized by collaboration. Accordingly, 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.

  FIG. 7 shows the configuration of the terminal device 12. The terminal device 12 includes an antenna 30, an RF unit 32, a baseband processing unit 34, and a control unit 36. The antenna 30, the RF unit 32, the baseband processing unit 34, and the control unit 36 perform operations corresponding to the antenna 20, the RF unit 22, the baseband processing unit 24, and the control unit 26 of FIG. Here, the description will focus on the different parts. As a network entry, the control unit 36 executes the sequence shown in FIG. 3 when receiving a control signal arranged at the head portion of the downlink subframe via the RF unit 32 and the baseband processing unit 34. On the other hand, when the control unit 36 does not receive the control signal arranged at the head portion of the downlink subframe via the RF unit 32 and the baseband processing unit 34 and receives the D signal, the R signal corresponding to the D signal is received. Then, RNG-REQ is transmitted. The subsequent processing is the same as in FIG.

  Here, when the control unit 36 receives a plurality of D signals, the RF unit 32 measures received power for each of the plurality of D signals. The control unit 36 selects the maximum received power among the plurality of received powers. Further, the control unit 36 specifies a D signal corresponding to the selected received power and transmits an R signal corresponding to the D signal. When receiving a plurality of D signals, the control unit 36 may transmit an R signal corresponding to each of the plurality of D signals. That is, the control unit 36 transmits a plurality of R signals. At that time, the control unit 26 of the base station apparatus 10 (not shown) selects one of the plurality of R signals.

  Further, after the network entry is completed, the control unit 36 acquires DL MAP and UL MAP via the RF unit 32 and the baseband processing unit 34, and grasps the burst allocated to itself. The terminal device 12 receives or transmits the OFDM signal in the assigned burst. In addition, when RNG-REQ is transmitted by an R signal instead of the ranging area, future DL MAP and UL MAP may be included in the allocated burst.

  The operation of the communication system 100 configured as above will be described. FIG. 8 is a flowchart showing a network entry procedure by the base station apparatus 10. FIG. 8 corresponds to Step 10 to Step 14 of FIG. The control unit 26 generates a control signal (S50) and generates a plurality of D signals based on the control signal (S52). The control unit 26 arranges a control signal at the head part of the downlink subframe and arranges a plurality of D signals in association with the directivity pattern (S54). Further, the control unit 26 arranges the R signal in association with each of the plurality of D signals. When the RF unit 22 and the baseband processing unit 24 receive a random access signal in the ranging area or the R signal (Y in S56), the control unit 26 continues the network entry process (S58). On the other hand, if the RF unit 22 and the baseband processing unit 24 do not receive the random access signal in the ranging area or the R signal (N in S56), the processing is terminated. Further, the processing from step 50 is repeatedly executed.

  FIG. 9 is a flowchart showing a network entry procedure by the terminal device 12. When the RF unit 32 and the baseband processing unit 34 receive the control signal for the head portion of the downlink subframe (Y in S70), the control unit 36 enters the ranging area via the baseband processing unit 34 and the RF unit 32. Then, a random access signal is transmitted (S72). On the other hand, if the RF unit 32 and the baseband processing unit 34 do not receive the control signal of the head portion of the downlink subframe (N in S70) and receive the D signal (Y in S74), the control unit 36 An R signal corresponding to the received D signal is transmitted via the processing unit 34 and the RF unit 32 (S76). Thereafter, the control unit 36 continues the network entry process (S78). On the other hand, if the D signal is not received (N in S74), the process is terminated.

  A modification of this embodiment will be described. In the embodiment, the control signal is arranged at the head portion of the downlink subframe, and a plurality of D signals are arranged in the downlink subframe. In addition, by applying dithering to a plurality of D signals, the reception probability of the D signals at the terminal device 12 is improved. However, since the D signal also includes a part of the content of the control signal, this corresponds to the fact that a part of the content of the control signal is repeatedly notified. As a result, the bandwidth for transmitting data decreases. The modification is intended to suppress a decrease in a band for transmitting data while maintaining an improvement in the reception probability of the D signal in the terminal device 12.

  The communication system 100 according to the modified example is the same type as that in FIG. 1, the base station device 10 is the same type as that in FIG. 4, and the terminal device 12 is the same type as that in FIG. Therefore, these will be described focusing on differences from the embodiments. The control unit 26 of the base station apparatus 10 defines a frame as shown in FIGS. The control unit 26 measures the number of R signal receptions within a predetermined period via the RF unit 22 and the baseband processing unit 24. Further, the control unit 26 stores a threshold value to be compared with the number of receptions.

  FIG. 10 shows a data structure of a table stored in the control unit 26 according to the modification of the present invention. As illustrated, a threshold value column 200 and a transmission frequency column 202 are included. The threshold value column 200 includes a plurality of threshold values such as “A1” and “A2”. Here, it is assumed that the value becomes larger as it goes up, that is, closer to “A1”. Further, while being associated with each threshold value, the transmission frequency column 202 includes a plurality of transmission frequency values such as “B1” and “B2”. Here, the transmission frequency corresponds to the frequency of arranging the D signal and the R signal, and can be said to be the ratio of the frame in which the D signal and the R signal are arranged. Further, it is assumed that the value becomes larger as the level is higher, that is, closer to “B1”.

  The control unit 26 compares the measured number of receptions with a plurality of threshold values included in the threshold value column 200, selects a threshold that satisfies the relationship “number of receptions> threshold”, and selects Among the threshold values, the maximum value is specified. Further, the control unit 26 extracts a transmission frequency value corresponding to the specified threshold value from the transmission frequency column 202. The control unit 26 arranges the D signal and the R signal in the frame according to the extracted transmission frequency value. For example, if the value of the extracted transmission frequency is “1/2”, the control unit 26 arranges the D signal and the R signal in one of the two frames. That is, the control unit 26 adjusts the transmission frequency of the D signal in the downlink subframe according to the reception state of the R signal.

  FIG. 11 is a flowchart showing a procedure for changing the transmission frequency by the base station apparatus 10 according to the modification of the present invention. When receiving the R signal via the RF unit 22 and the baseband processing unit 24, the control unit 26 measures the reception frequency of the R signal (S90). The control unit 26 compares the measurement result with the threshold value (S92). From the comparison result, if the transmission frequency should be changed from the current value (Y in S94), the control unit 26 changes the transmission frequency of the D signal (S96). On the other hand, if the transmission frequency should not be changed from the current value based on the comparison result (N in S94), the control unit 26 ends the process.

  Another modification of the present embodiment will be described. Similarly to the embodiment, the base station apparatus 10 according to another modification also applies dithering to a plurality of D signals. However, the base station apparatus 10 which concerns on another modification estimates the direction where the other base station apparatus 10 exists by measuring a propagation environment previously. Also, the base station apparatus 10 performs dithering so that the antenna directivity does not face in the estimated direction (hereinafter referred to as “existing direction”). Furthermore, the base station apparatus 10 arranges another D signal at another frequency, and directs the antenna directivity with respect to the other D signal in the existing direction.

  A communication system 100 according to another modification is the same type as that in FIG. 1, the base station device 10 is the same type as that in FIG. 4, and the terminal device 12 is the same type as that in FIG. 7. Therefore, these will be described focusing on differences from the embodiments. The control unit 26 measures the surrounding propagation environment in the unused burst. For example, the control unit 26 causes the baseband processing unit 24 to calculate a weight vector based on a signal received in an unused burst. For example, the baseband processing unit 24 derives a weight vector by using a preamble included in the received signal. Further, the control unit 26 calculates a correlation value between the weight vector derived by the baseband processing unit 24 and each of a plurality of dithering weight vectors stored in advance.

  The control unit 26 excludes the dithering weight vector having a correlation value larger than the threshold value, and uses the remaining weight vector for transmission of the D signal and reception of the R signal. Since these uses should just be made as mentioned above, description is abbreviate | omitted here. The control unit 26 causes the baseband processing unit 24 to measure the surrounding propagation environment even at another frequency. Based on the comparison between the excluded weight vector for dithering and the correlation value of the measured weight vector, if possible, the control unit 26 transmits the excluded dithering weight vector to the D signal. Used to receive R signal. In this way, the control unit 26 determines the arrangement of bursts to which each D signal is assigned according to the measurement result.

  FIG. 12 shows a frame format according to another modification of the present invention. FIG. 12 is shown similarly to FIGS. 5 (a)-(b). However, the D signal is arranged not only at the frequency at which the D1 signal is arranged, but also at the frequency at which the D1 'signal is arranged. For example, at the frequency where the D1 signal is arranged, the control unit 26 recognizes the presence of another base station apparatus 10 in the presence direction. At that time, the control unit 26 controls the antenna directivity of the DM signal from the D1 signal so that the antenna directivity is not directed to the vicinity of the existing direction. On the other hand, at the frequency where the D1 ′ signal is arranged, the control unit 26 does not recognize the presence of another base station device 10 in the direction of presence. At this time, the control unit 26 transmits the DM ′ signal from the D1 ′ signal while using the antenna directivity that is not used for the DM signal from the D1 signal. The same antenna directivity is used for the R1 signal to the RM signal and the R1 'signal to the RM' signal.

  Another modification of the present embodiment will be described. So far, the arrangement of the D signal and the R signal in the network entry processing has been described. Still another modified example relates to notification of control signals, particularly DL MAP and UL MAP, to the terminal device 12 after the network entry process is completed, that is, the terminal device 12 communicating with the base station device 10. As described above, since the information regarding the burst allocated by the base station apparatus 10 is included in the DL MAP and the UL MAP, the terminal apparatus 12 must receive the DL MAP and the UL MAP even during communication.

  Since the data signal is unicasted, AAS can be applied to the data signal. However, since DL MAP and UL MAP are broadcasted, AAS cannot be applied to DL MAP or the like. As a result, the communicable distance between the terminal apparatus 12 and the base station apparatus 10 is limited to an area where broadcast communication is possible. Therefore, in another modification, DL MAP and UL-MAP are stored in the D signal. Hereinafter, only DL MAP will be described for the sake of clarity.

  A communication system 100 according to another modification is the same type as that in FIG. 1, the base station device 10 is the same type as that in FIG. 4, and the terminal device 12 is the same type as that in FIG. Therefore, these will be described focusing on differences from the embodiments. The control unit 26 generates a DL MAP. When a frame to be transmitted is an i-th frame, the control unit 26 generates a DL MAP for the i + 1 frame to be transmitted immediately after the frame i. That is, the control unit 26 generates in advance a DL MAP for a frame that should be placed downstream of the transmission target frame. Therefore, the DL MAP for the i-th frame has already been generated.

  In addition, the control unit 26 includes the DL MAP for the i-th frame that has already been generated in the control signal, and includes the DL MAP for the i + 1-th frame in each of the plurality of D signals. That is, the control unit 26 arranges the DL MAP for the i-th frame at the beginning of the downlink subframe, and arranges the DL MAP for the i + 1-th frame behind the beginning of the downlink subframe. As in the past, the antenna directivity control for each of the plurality of D signals is made different.

  Here, the reason for making DL MAP for the D signal in this way will be described. The DL MAP included in the control signal is arranged before the downlink burst that is the target of the MAP. Therefore, the terminal device 12 can receive the downlink burst included in the same downlink subframe even after receiving the DL MAP and grasping the content thereof. On the other hand, a plurality of D signals may be arranged after a downstream burst that is a target of MAP. In this case, similarly to the control signal, DL MAP for the downlink burst to be transmitted is included in the D signal. When the terminal device 12 receives the DL MAP and grasps the contents thereof, the terminal device 12 may have already deleted the target downlink burst. As a result, the terminal device 12 cannot receive the downlink burst included in the same downlink subframe. In order to solve such a problem, in another modification, as described above, the DL MAP for the D signal is determined.

  FIG. 13 shows a frame format according to still another modification of the present invention. FIG. 13 is shown similarly to FIGS. 5 (a)-(b). In FIG. 13, a plurality of frames are shown such as the i-th frame and the (i + 1) -th frame. A DL MAP (denoted as “DL MAP (i)” in FIG. 13) for the i-th frame is arranged at the beginning of the downlink subframe in the i-th frame. Following this, a D signal (indicated as “D (i + 1)” in FIG. 13) including the DL MAP for the (i + 1) th frame is arranged. Furthermore, DL MAP (denoted as “DL MAP (i + 1)” in FIG. 13) for the (i + 1) th frame is arranged at the beginning of the downlink subframe in the (i + 1) th frame. Following this, a D signal (indicated as “D (i + 2)” in FIG. 13) including DL MAP for the i + 2th frame is arranged.

  FIG. 14 is a flowchart showing a DL-MAP transmission procedure by the base station apparatus 10 according to still another modification of the present invention. The control unit 26 acquires the DL MAP related to the i-th frame and generates the DL MAP related to the i + 1-th frame (S110). The control unit 26 arranges the DL MAP related to the i-th frame at the head portion of the downlink subframe, and stores the DL MAP related to the i + 1-th frame in the D signal (S112).

  FIG. 15 is a flowchart showing a DL-MAP transmission procedure by the terminal apparatus 12 according to still another modification of the present invention. When the D signal is used (Y of S130), that is, when DL MAP is acquired by the D signal, the control unit 36 receives the D signal via the RF unit 32 and the baseband processing unit 34. (S136). The control unit 36 specifies a downlink burst to be received in the next downlink subframe (S138). On the other hand, when the D signal is not used (N in S130), the control unit 36 receives the DL MAP of the head portion of the downlink subframe via the RF unit 32 and the baseband processing unit 34 (S132). The control unit 36 specifies the downlink burst to be received (S134).

  According to the embodiment of the present invention, a plurality of corresponding combinations of the D signal and the R signal are generated, and the antenna directivity control is made common in each combination. You can control gender. In addition, since a plurality of combinations corresponding to the D signal and the R signal are generated and the antenna directivity control is made common in each combination, the reception characteristic of the R signal can be made equal to the reception characteristic of the D signal. In addition, since dithering is executed for the corresponding combination of the D signal and the R signal, the reception characteristics of the D signal and the R signal can be improved. In addition, since the reception characteristics of the D signal and the R signal are improved, the broadcast communication quality can be improved. In addition, since the broadcast communication quality is improved, it is possible to reduce the influence of the communication quality imbalance between unicast and broadcast.

  In addition, since the reception characteristics of the random access signal are improved, the area covered by the base station apparatus can be expanded. In addition, since at least part of the information of the control signal is included in each of the plurality of D signals, the broadcast quality can be improved by the presence of the control signal and the plurality of D signals. In addition, since the burst arrangement for the D signal and the R signal is made common, transmission of information relating to the allocation of the random access signal can be omitted. Since the burst arrangement for the D signal and the R signal is made common, processing in the terminal device can be simplified. Moreover, since each D signal is allocated according to the propagation environment, each D signal can be allocated so as to be suitable for the propagation environment. Moreover, since the antenna directivity of each D signal is controlled according to the propagation environment, each D signal can be transmitted so as to be suitable for the propagation environment.

  Moreover, since the transmission frequency of D signal is adjusted according to the reception condition of R signal, the fall of transmission efficiency can be suppressed. Moreover, since the transmission frequency of the D signal is adjusted according to the reception status of the R signal, it is possible to suppress a decrease in transmission efficiency while maintaining the broadcast communication quality. In addition, since information on a frame subsequent to the frame in which the control signal is arranged is included in each of the plurality of D signals, the degree of freedom of bursts assigned to the plurality of D signals can be improved. In addition, since information regarding a frame subsequent to the frame in which the control signal is arranged is included in each of the plurality of D signals, the subsequent frame can be received even when the D signal is received. In addition, since the antenna directivity control for each of the plurality of D signals is made different, the quality of the broadcast can be improved.

  In the above, this invention was demonstrated based on the Example. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. .

  In the embodiment of the present invention, the communication system 100 employs OFDMA. However, the present invention is not limited to this, and the communication system 100 may adopt only TDMA without adopting OFDMA. In this case, the physical layer may be OFDM or SC. According to this modification, the present invention can be applied to various communication systems. That is, it is only necessary to define a frame formed by a plurality of bursts and to arrange a control signal to be broadcast at the head portion of the frame.

  In the embodiment of the present invention, the communication system 100 associates the D signal and the R signal on a one-to-one basis, and then targets the arrangement of the D signal in the downlink subframe and the arrangement of the R signal in the uplink subframe. Establish rules that However, the present invention is not limited to this. For example, the communication system 100 may define a rule that does not cover the arrangement of D signals in downlink subframes and the arrangement of R signals in uplink subframes. In this case, the base station apparatus 10 includes information for identifying the burst to which the corresponding R signal is assigned in the D signal. According to this modification, it is possible to improve the degree of freedom in the arrangement of the D signal in the downlink subframe or the arrangement of the R signal in the uplink subframe.

It is a figure which shows the structure of the communication system which concerns on the Example of this invention. FIGS. 2A and 2B are diagrams illustrating a frame format in a communication system to be compared with the communication system in FIG. It is a sequence diagram which shows the network entry procedure in the communication system of FIG. It is a figure which shows the structure of the base station apparatus of FIG. FIGS. 5A and 5B are diagrams illustrating a frame format in the base station apparatus of FIG. 6A to 6C are diagrams illustrating antenna directivities generated in the control unit of FIG. It is a figure which shows the structure of the terminal device of FIG. It is a flowchart which shows the network entry procedure by the base station apparatus of FIG. It is a flowchart which shows the network entry procedure by the terminal device of FIG. It is a figure which shows the data structure of the table memorize | stored in the control part which concerns on the modification of this invention. It is a flowchart which shows the procedure of the transmission frequency change by the base station apparatus which concerns on the modification of this invention. It is a figure which shows the frame format which concerns on another modification of this invention. It is a figure which shows the frame format which concerns on another modification of this invention. It is a flowchart which shows the transmission procedure of DL-MAP by the base station apparatus which concerns on another modification of this invention. It is a flowchart which shows the transmission procedure of DL-MAP by the terminal device which concerns on another modification of this invention.

Explanation of symbols

  10 base station apparatus, 12 terminal apparatus, 20 antenna, 22 RF section, 24 baseband processing section, 26 control section, 30 antenna, 32 RF section, 34 baseband processing section, 36 control section, 100 communication system.

Claims (13)

A base station device that defines a frame formed by a downlink subframe including a plurality of bursts and an uplink subframe including a plurality of bursts,
A generator for generating at least two control signals in one downlink subframe for designating a burst for transmitting a random access signal to a terminal device;
A transmission unit that transmits at least two control signals generated in the generation unit while allocating them to different bursts in a downlink subframe;
In the bursts specified in each of the at least two control signals transmitted from the transmission unit and in the uplink subframe corresponding to the bursts to which the respective control signals are assigned on a one-to-one basis, A receiver for receiving a random access signal;
A control unit that controls operations of the receiving unit and the transmitting unit;
The base station apparatus characterized in that the control unit shares antenna directivity control in a corresponding combination of a burst to which a control signal is assigned and a burst to which a random access signal is assigned.   2. The transmission unit according to claim 1, wherein the transmission unit arranges a burst to which each control signal is allocated in a downlink subframe so as to be symmetric with an arrangement in the uplink subframe of a burst to which each random access signal is allocated. The base station apparatus as described. It further comprises a measurement unit for measuring the propagation environment,
The base station apparatus according to claim 1 or 2, wherein the transmission unit determines an arrangement of bursts to which each control signal is assigned according to a measurement result in the measurement unit.   The transmission unit also arranges a control signal in the burst at the beginning of the downlink subframe, and the control signal arranged in the burst at the beginning of the downlink subframe according to the reception status of the random access signal in the reception unit The base station apparatus according to any one of claims 1 to 3, wherein the transmission frequency of control signals other than is adjusted. A base station device that defines a frame including a plurality of bursts,
A generator for generating a first control signal and a plurality of second control signals;
A transmission unit that arranges the first control signal generated in the generation unit in a burst at the beginning of a frame and transmits a plurality of second control signals while arranging them in different bursts;
The generation unit includes at least part of information of a first control signal in each of a plurality of second control signals. A base station apparatus that repeatedly defines a frame including a plurality of bursts,
A generator for generating a first control signal and a plurality of second control signals;
A transmission unit that arranges the first control signal generated in the generation unit in a burst at the beginning of a frame and transmits a plurality of second control signals while arranging them in different bursts;
The generation unit includes information on a frame in which the first control signal is arranged in the first control signal, and information on a frame subsequent to the frame in which the first control signal is arranged in the plurality of second controls. A base station apparatus which is included in each of signals. A control unit for controlling the operation of the transmission unit;
The base station apparatus according to claim 5 or 6, wherein the control unit makes different antenna directivity control for each of a plurality of second control signals. Control for specifying a burst for transmitting a random access signal to a terminal device, in which a frame formed by a downlink subframe including a plurality of bursts and an uplink subframe including a plurality of bursts is defined. Generating at least two signals in one downstream subframe;
Transmitting the generated at least two control signals while assigning them to different bursts in a downlink subframe;
A random access signal from a terminal device is transmitted in a burst specified by each of at least two transmitted control signals, and in a burst in an uplink subframe corresponding to each of the bursts to which each control signal is assigned. Receiving, and
Random access characterized in that the transmitting and receiving steps share antenna directivity control in a corresponding combination of a burst assigned a control signal and a burst assigned a random access signal. How to specify the signal. Generating a first control signal and a plurality of second control signals;
A frame including a plurality of bursts is defined, the generated first control signal is arranged in the burst at the head portion of the frame, and the plurality of second control signals are transmitted in different bursts. With steps,
The generating step includes at least part of information of the first control signal in each of the plurality of second control signals. Generating a first control signal and a plurality of second control signals;
A frame including a plurality of bursts is repeatedly defined, and the generated first control signal is arranged in the burst at the head portion of the frame, and the plurality of second control signals are arranged in different bursts and transmitted. And a step of
In the generating step, information related to a frame in which the first control signal is arranged is included in the first control signal, and information relating to a frame subsequent to the frame in which the first control signal is arranged A communication method characterized by being included in each of the control signals. Control for specifying a burst for transmitting a random access signal to a terminal device, in which a frame formed by a downlink subframe including a plurality of bursts and an uplink subframe including a plurality of bursts is defined. Generating at least two signals in one downstream subframe;
Transmitting the generated at least two control signals while assigning them to different bursts in a downlink subframe;
A random access signal from a terminal device is transmitted in a burst specified by each of at least two transmitted control signals, and in a burst in an uplink subframe corresponding to each of the bursts to which each control signal is assigned. Receiving, and
In the transmitting step and the receiving step, a program for causing a computer to execute common antenna directivity control in a corresponding combination of a burst assigned a control signal and a burst assigned a random access signal . Generating a first control signal and a plurality of second control signals;
A frame including a plurality of bursts is defined, the generated first control signal is arranged in the burst at the head portion of the frame, and the plurality of second control signals are transmitted in different bursts. With steps,
The generating step causes the computer to execute including at least a part of information of the first control signal in each of the plurality of second control signals. Generating a first control signal and a plurality of second control signals;
A frame including a plurality of bursts is repeatedly defined, and the generated first control signal is arranged in the burst at the head portion of the frame, and the plurality of second control signals are arranged in different bursts and transmitted. And a step of
In the generating step, information related to a frame in which the first control signal is arranged is included in the first control signal, and information relating to a frame subsequent to the frame in which the first control signal is arranged A program that causes a computer to execute inclusion in each control signal.

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