JP2007158469A - Allocation method, and base station apparatus utilizing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base station apparatus capable of utilizing both communication efficiency and resource utilizing efficiency. <P>SOLUTION: A traffic measurement section 44 measures traffic between the base station apparatus 10 and a plurality of terminals on the basis of information noticed by a processing section 22. When the traffic measured by the traffic measurement section 44 exceeds a threshold value relative to the traffic, a signal processing section 40 makes a slot allocation section 42 arrange a preamble to each of communication slots. Further, when the traffic measured by the traffic measurement section 44 is smaller than the threshold value relative to the traffic in the case that the allocation means is executed by other methods than a slot connection allocation method, the signal processing section 40 switches the allocation method into the slot connection allocation method. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a scheduling technique, and more particularly to a communication slot allocation method for a communication target terminal apparatus and a base station apparatus using the same.

Generally, in wireless communication, effective use of limited frequency resources is 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 technique for communicating with a plurality of terminal devices at the same frequency and at the same timing by adjusting the antenna directivity pattern for each of the plurality of terminal devices. Such a spatial multiplexing scheme is equivalent to separating signals between a plurality of terminal devices based on antenna directivity patterns. An adaptive array antenna technique is applied to form such a directivity pattern. In general, in the spatial multiplexing method, a scheduling process for assigning a plurality of terminal devices to a time axis having a slot as a unit time and a space axis having a space as a unit is required. (For example, refer to Patent Document 1).
Japanese Patent Laid-Open No. 10-262277

  In general, when spatial multiplexing is used, signals transmitted from a plurality of spatially multiplexed terminal devices are calculated by calculating a weight using a preamble arranged at the head of each spatially multiplexed slot. Separate on the receiving side. However, the preamble for calculating the weight needs to be arranged at the same timing in the same slot. In addition, for example, slot allocation may be performed so as to improve communication efficiency by connecting two slots and not arranging a preamble in the rear slot. In such a case, since there is no preamble in the rear slot, there is a problem that other terminal devices cannot be spatially multiplexed and resource utilization efficiency is reduced. In other words, within the same resource, there is a trade-off relationship between improvement in communication efficiency and improvement in utilization efficiency, and it is difficult to improve both at the same time.

  The present invention has been made in view of such a situation, and an object of the present invention is to increase communication efficiency without reducing system resource utilization efficiency when assigning slots to a terminal device that performs space division multiplexing. It is to provide a base station apparatus that can be used.

  In order to solve the above-described problem, a base station apparatus according to an aspect of the present invention uses a spatial multiplexing scheme and allocates communication slots to a plurality of terminal apparatuses so as to overlap in time. In this case, a slot allocation unit, a communication amount measurement unit, and a signal processing unit are provided. The slot allocation unit, for any one of a plurality of terminal devices, a preamble that overlaps in time with a preamble allocated to a communication slot allocated to another communication terminal Assign a plurality of consecutive communication slots arranged only in. The communication amount measuring unit measures the communication amount with a plurality of terminal devices. When the communication amount measured by the communication amount measurement unit exceeds a threshold related to the communication amount, the signal processing unit causes the slot allocation unit to arrange a preamble in each communication slot.

  Here, “assigning communication slots so as to overlap in time” includes assigning a plurality of terminal devices in the same slot time by spatial multiplexing. In addition, when a plurality of slot times are assigned to a single terminal device, other terminal devices may be assigned to other spaces so as to overlap with any one of the plurality of slot times. Including. Further, “overlapping” includes the case where the heads of the assigned slot times are not the same, and at least a part of the slot times may be assigned so as to be spatially multiplexed with slots in other spaces. The “preamble” includes a known signal and a unique word that are arranged at the head of the slot time and are used for synchronization processing and space separation. According to this aspect, the use efficiency of resources can be improved by prohibiting the allocation of a plurality of consecutive slots in which the preamble is arranged only in the head slot, triggered by an increase in the traffic.

  After the preamble is placed in each of the communication slots, the signal processing unit, when the communication amount measured by the communication amount measurement unit becomes smaller than the threshold related to the communication amount, a plurality of preambles arranged only in the first slot The terminal device to which the continuous communication slot is assigned is again assigned a plurality of continuous communication slots in which the preamble is arranged only in the head slot, and the terminal device can perform higher-speed communication. Execution may be allowed. According to this aspect, the “allocation of a plurality of consecutive slots in which the preamble is arranged only in the first slot”, which is prohibited as the traffic volume increases, is allowed again when the traffic volume subsequently decreases. Thus, communication efficiency can be improved.

  The slot allocation unit includes a reception level measurement unit that measures a reception level of a signal transmitted from the terminal device, and an allocation confirmation unit that confirms that a slot adjacent to the communication slot allocated to the terminal device is an empty slot. The reception level measured by the reception level measurement unit exceeds a threshold related to the reception level, and a slot adjacent to the communication slot allocated to the terminal device by the allocation confirmation unit is an empty slot. When it is confirmed that the terminal device is confirmed, an allocation determination unit that determines to allocate a plurality of continuous communication slots in which a preamble is arranged only in the first slot to the terminal device may be included. According to this aspect, an unused resource can be effectively used by assigning a terminal device having a high reception level to an unused resource.

  When there are a plurality of terminal devices in which the reception level measured by the reception level measurement unit exceeds a threshold related to the reception level, the allocation determination unit selects a terminal device with a higher reception level among the plurality of terminal devices. On the other hand, a plurality of continuous communication slots in which the preamble is arranged only in the head slot may be assigned with priority. According to this aspect, by allocating a plurality of continuous communication slots in which the preamble is arranged only in the first slot, the terminal device having a high reception level is given priority so that resources can be released early. Communication efficiency can be improved, and resource utilization efficiency can be improved.

  Another aspect of the present invention is an allocation method. This method is an allocating method that uses a spatial multiplexing method to allocate communication slots to a plurality of terminal devices so as to overlap in time, and any one of the plurality of terminal devices. On the other hand, assigning a plurality of consecutive communication slots in which a preamble that overlaps in time with a preamble arranged in a communication slot assigned to another communication terminal is arranged only in the first slot; Measuring the amount of communication with the terminal device, and placing a preamble in each of the communication slots when the amount of communication measured by the measuring step exceeds a threshold related to the amount of communication. According to this aspect, the use efficiency of resources can be improved by prohibiting the allocation of a plurality of continuous communication slots in which the preamble is arranged only in the head slot, triggered by the increase in the traffic.

  Yet another embodiment of the present invention is a program for causing a computer to execute. This program is an allocating method for allocating communication slots to a plurality of terminal devices so as to overlap in time using a spatial multiplexing method via a wireless network. For any one of the terminal devices, a plurality of consecutive communication slots in which a preamble that overlaps in time with a preamble allocated in a communication slot allocated to another communication terminal is allocated only in the first slot is allocated. And a step of measuring a communication amount between the plurality of terminal devices, and a step of arranging a preamble in each of the communication slots when the communication amount measured by the measuring step exceeds a threshold relating to the communication amount And including. According to this aspect, the use efficiency of resources can be improved by prohibiting the allocation of a plurality of consecutive slots in which the preamble is arranged only in the head slot, triggered by an increase in the traffic.

  In the step of arranging, when a communication amount measured by the measuring step becomes smaller than a threshold related to the communication amount after arranging a preamble in each of the communication slots, a plurality of preambles arranged only in the first slot are arranged. A terminal device that has been assigned a continuous communication slot is again assigned a plurality of continuous communication slots in which a preamble is arranged only in the first slot, and at the same time, the terminal device performs faster communication. May be allowed.

  The assigning step includes a step of measuring a reception level of each signal transmitted from a plurality of terminal devices, and a slot adjacent to each communication slot assigned to the plurality of terminal devices is assigned to any terminal device. And a step of confirming that the reception level measured by the reception level measurement unit of the plurality of terminal devices exceeds a threshold related to the reception level, and the step of confirming, When it is confirmed that the slot adjacent to the communication slot assigned to the terminal device is not assigned to any terminal device other than the terminal device, the preamble is arranged only in the first slot for the terminal device. Determining to allocate a plurality of consecutive communication slots; Good.

  In the case where there are a plurality of terminal devices in which the reception level measured by the step of measuring the reception level exceeds a threshold relating to the reception level, the determining step includes a terminal having a higher reception level among the plurality of terminal devices. A plurality of continuous communication slots in which the preamble is arranged only in the first slot may be preferentially assigned to the apparatus.

  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, when assigning the slot of the several terminal device which performs space division multiplexing, communication efficiency can be improved, without reducing the utilization efficiency of a system resource.

  Before describing the present invention in detail, an outline will be described. The 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. By assigning one time slot per frame to one terminal device, in the case of the (π / 4 shift) QPSK modulation method, a data rate of 32 kbps is realized. In the case of the BPSK modulation method, a data rate of 16 kbps is realized. In the case of the 16QAM modulation method, a data rate of 64 kbps is realized. In consideration of the uplink and downlink, two time slots are assigned to one terminal device in units of frames. Further, in order to improve communication efficiency, one terminal device is assigned to a plurality of continuous time slots (hereinafter referred to as “concatenated slots”) in which a preamble is arranged only in the first slot (hereinafter referred to as “ "Slot concatenation allocation"). Note that the “preamble” includes a known signal, a unique word, and the like that are arranged at the head of the slot time and are used to separate signals for each user subjected to synchronization processing and spatial multiplexing.

  The base station apparatus according to the present embodiment further applies SDMA (Space Division Multiple Access), and allocates a plurality of terminal apparatuses to one time slot. Here, when slot concatenation allocation is performed, since there is no preamble in the rear slot, other terminal devices cannot be spatially multiplexed, and resource utilization efficiency is reduced. Therefore, in the base station apparatus according to the present embodiment, when the communication amount in the base station apparatus exceeds a predetermined threshold value, the slot allocation method of the terminal apparatus performing slot concatenation allocation is changed to normal slot allocation. It was decided to forcibly release switching and slot allocation. As a result, resources are released and spatial multiplexing is possible in slots that could not be spatially multiplexed, so that the utilization efficiency can be improved. The “resource” is a concept including time or space to which a terminal device can be allocated. In addition, when the traffic is below a predetermined threshold value, the communication efficiency is improved by performing slot concatenation allocation to a terminal device that can release resources early. Details will be described later.

  FIG. 1 is a diagram illustrating a configuration example of a base station apparatus 10 according to the 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 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. 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. Note that the processing of the multiplication unit and the addition unit (not shown) corresponds to synthesis while performing weighting. Further, a training signal stored in advance during the period of the training signal is output as a reference 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. 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.

  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 is used as the modulation method. On the other hand, the demodulation performs delay detection and the like.

  The IF unit 26 is connected to a network (not shown), and outputs signals of individual terminals demodulated by the modem unit 24 to a network (not shown) as reception processing. In addition, if the information indicating the communication request is included in any of the demodulated individual terminal signals, the IF unit 26 determines the terminal device related to the information indicating the communication request to the control unit 30. Notify the information shown. 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 control unit 30 uses the communication request notified from the IF unit 26 and the received signal sent from the processing unit 22 as inputs, and allocates radio channels to a plurality of terminal devices to 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 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. Details will be described later.

  FIGS. 2A and 2B are diagrams illustrating a configuration example of a frame to which slots are assigned by the control unit 30. FIG. Each of FIGS. 2A and 2B corresponds to a case where the control unit 30 assigns time slots to a plurality of terminal devices. In particular, FIG. 2A shows an example of a frame structure when slot concatenation assignment is performed. 2 (a) and 2 (b) show 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 radio channels on the spatial axis in the direction of the vertical axis. The arrangement of That is, multiplexing on the horizontal axis corresponds to TDMA, and multiplexing on the vertical axis corresponds to SDMA.

  Each of FIGS. 2A and 2B includes “first time slot” to “fourth time slot” in one frame. 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 each of FIGS. 2 (a) and 2 (b), the squares (reference numerals 34, 36, or 38) and described as “A”, “B” or “C”. In addition, in the transmission signal of each terminal signal, “P” or “P” or “A”, “B”, or “C” is written at the head of the square in order to clearly indicate the time slot including the preamble. “P ′” is displayed. Here, “A”, “B”, and “C” indicate different terminal devices. Further, “P” and “P ′” indicate separate preambles. In addition, such a display is performed in order to clarify the description, and actually, an identification number other than these may be given to the terminal device or the preamble.

  In the slot allocation method illustrated in FIG. 2A, the control unit 30 allocates the terminal device “A” to the first space 100 of the “first time slot”. Further, the control unit 30 assigns “B” to the second space 110 of the “first time slot” as a terminal device that is spatially multiplexed with “A” so that the respective preambles overlap in time. The control unit 30 also assigns “A” to the first space 100 of the “second time slot”. In this case, the preamble P is not arranged in the first space 100 of the “second time slot”. Therefore, the amount of data that can be transmitted by “A” can be increased by the amount of the preamble P, so that the communication efficiency is improved. However, since the preamble P is not arranged in the first space 100 of the “second time slot”, no other terminal device is assigned to the second space 110 of the “second time slot” as described above. . This is because space separation becomes difficult if the preambles are not arranged so as to overlap in time. Accordingly, resource utilization efficiency is reduced. In the following, a plurality of consecutive slots in which a preamble is arranged only in the head slot, such as “first time slot” and “second time slot” in the first space 100 illustrated in FIG. Is referred to as a “connection slot”.

  In the slot allocation method illustrated in FIG. 2B, the control unit 30 performs the terminal device “A” in the first space 100 of “first time slot” and “second time slot” as normal slot allocation. Assign. In addition, the control unit 30 assigns “B” to the second space 110 of the “first time slot” as a terminal device that is spatially multiplexed with “A”. The difference from FIG. 2A is that the preamble P is arranged in the first space 100 of the “second time slot”. Further, as illustrated in FIG. 2B, the control unit 30 is assigned “C” as a terminal device that is spatially multiplexed with “A” in the second space 110 of the “second time slot”. Therefore, the slot allocation illustrated in FIG. 2B has higher resource utilization efficiency than the slot concatenation allocation illustrated in FIG. On the other hand, the slot allocation illustrated in FIG. 2B has lower communication efficiency than the slot concatenation allocation illustrated in FIG.

  Therefore, when the amount of communication in the base station apparatus 10 increases by the control unit 30 described later, that is, when the number of terminal apparatuses to be allocated increases, switching from the allocation method of FIG. 2A to FIG. It is said that resource utilization efficiency will be improved by canceling the consolidated allocation. On the other hand, when the communication amount in the base station apparatus 10 is small, the base station apparatus 10 switches from the allocation method of FIG. 2B to the allocation method of FIG. By executing this, communication efficiency was increased.

  Here, the control unit 30 will be described in detail with reference to FIG. FIG. 3 is a diagram illustrating a configuration example of the control unit 30 of FIG. The control unit 30 includes a signal processing unit 40, a slot allocation unit 42, and a communication amount measurement unit 44.

  The slot allocation unit 42 performs slot concatenation allocation for any one of a plurality of terminal devices. The slot connection allocation is performed based on the slot connection allocation request received from the terminal device via the processing unit 22. Further, the base station apparatus 10 may autonomously carry out based on the resource usage state. At this time, a plurality of continuous communication slots in which the preamble is arranged only in the head slot are assigned to the terminal device to which slot concatenation assignment is performed. At this time, time slots are assigned to other communication terminals so as to overlap in time with the preamble. For example, as shown in the first space 100 of FIG. 2A, slot concatenation assignment is performed for “A”. In addition, “A” and “B” are spatially multiplexed by assigning “B” to “first time slot” which is the first slot of a plurality of slots subject to slot concatenation assignment.

  The communication amount measurement unit 44 measures the communication amount between the base station device 10 and the plurality of terminal devices based on the information notified from the processing unit 22. The amount of communication may be derived from the number of slots used by the terminal device per frame or the number of terminal devices that are performing communication.

  When the traffic volume measured by the traffic volume measurement unit 44 exceeds a threshold value related to the traffic volume (hereinafter referred to as “second threshold value”), the signal processing unit 40 A preamble is arranged in each communication slot. In other words, as shown in FIG. 2A, the assignment method of the terminal apparatus “A” in which the slot connection assignment has been performed is switched to the assignment method as shown in FIG. The switching of the allocation method may be executed by, for example, arranging a preamble at the head of the latter half slot when slot concatenation allocation is performed in the 2-slot section. Alternatively, the second half slot may be assigned to another terminal device. In either case, the communication efficiency for the preamble in the latter half slot is reduced, but since another terminal device can be allocated to another space in the latter half slot, the resource utilization efficiency can be improved. Also, the switching of the allocation method may be executed in consideration of the resource usage state.

  Further, when the allocation method is executed by an allocation method as illustrated in FIG. 2B other than the slot concatenation allocation, the signal processing unit 40 determines that the traffic volume measured by the traffic volume measuring unit 44 is the traffic volume. 2 may be switched to slot concatenation allocation as shown in FIG. 2A. In addition, when switching the allocation method to slot-linked allocation, higher-speed communication may be permitted to a terminal apparatus that newly performs continuous slot allocation so that resources can be released early. “Higher-speed communication” in the terminal device may be realized by causing the terminal device to change a modulation method, a coding rate, or the like.

  FIG. 4 is a diagram illustrating a configuration example of the slot allocation unit 42 of FIG. Slot allocation unit 42 includes an allocation determination unit 50, an allocation confirmation unit 52, and a reception level measurement unit 54.

  The reception level measurement unit 54 measures the reception levels of the respective signals transmitted from the plurality of terminal devices notified via the processing unit 22 and outputs them to the allocation determination unit 50. Here, the strength of the signal received from each of the plurality of terminal devices is defined as a reception level. 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 reception level measurement unit 54 may derive the reception level based on the reception weight vectors derived from the first processing unit 22a to the fourth processing unit 22d, respectively. This is because each of the reception weight vectors is calculated so as to correspond to each of the plurality of terminal devices.

  Also, the reception level measurement unit 54 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 reception level measurement unit 54 may derive the signal strength from the radio frequency signal or the radio unit side signal 200. Further, the reception level measuring unit 54 may acquire the downlink signal quality measured by the terminal device via a wireless line. The measured reception level may be RSSI (Received Signal Strength Indication), SIR (Signal to Interference Ratio), or SNR (Signal to Noise Ratio). Further, these reception levels may be combined.

  The allocation confirmation unit 52 confirms the usage status of consecutive slots to be slot-linked allocation in order to determine whether or not slot-linked allocation can be performed, and sends the result to the allocation determination unit 50. Notice. The “slot usage status” indicates “unused status” when the base station device 10 is not assigned to any of the plurality of terminal devices that are performing communication, and otherwise “used” State ". Here, when the terminal device that is going to implement slot concatenation assignment is currently carrying out normal slot assignment, the assignment confirmation unit 52 determines the slot adjacent to the slot to which the terminal device has already been assigned. Check the usage status. The “adjacent slot” includes not only a slot adjacent to a slot allocated to a terminal device that is going to perform slot concatenation allocation, but also a slot further adjacent to the adjacent slot. In other words, the assignment confirmation unit 52 confirms the use status of a plurality of consecutive slots adjacent to the slot assigned to the terminal device that is going to perform the slot concatenation assignment.

  When the allocation confirmation unit 52 determines that the slot concatenation allocation can be performed, the allocation determination unit 50 determines that the reception level measured by the reception level measurement unit 54 is a threshold (hereinafter referred to as “first level”) regarding the reception level. It is determined to perform slot concatenation allocation for terminal devices exceeding the threshold). However, as described above, when the communication amount measured by the communication amount measurement unit 44 in FIG. 3 exceeds the threshold, slot concatenation allocation is prohibited, and this is not the case.

  These configurations described above can be realized in hardware by a CPU, memory, or other LSI of an arbitrary computer, and in software, it is realized by a program having a communication function loaded in a memory. Here, functional blocks realized by the cooperation are depicted. 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.

  An operation of the base station apparatus 10 having the above configuration will be described. FIG. 5 is a flowchart illustrating an operation example of the control unit 30 of FIG. The flowchart shown in FIG. 5 may be executed in response to a request for slot connection assignment from the terminal device, or may be executed autonomously by the base station device 10. Also, when there is a request for slot concatenation assignment from a plurality of terminal devices within the same frame, a terminal device to be subjected to slot concatenation assignment is determined based on all reception levels of the requested terminal device.

  First, the allocation confirmation unit 52 confirms the free resource, that is, the slot usage state (S10). When the use state of the slot is managed by the management unit 32, the allocation confirmation unit 52 confirms by accessing the management unit 32. Next, it is determined whether or not slot concatenation allocation is possible in consideration of the confirmed amount of free resources (S12). In S12, when two or more unused slots are consecutive in the same space, it is determined that slot concatenation assignment is possible. Here, when it is determined that slot concatenation assignment is possible (Y in S12), the reception level measuring unit 54 measures the reception level of the terminal apparatus that has requested slot concatenation assignment (S14). Here, when the reception level exceeds the first threshold value (Y in S16), the slot allocation unit 42 determines whether the slot connection allocation is possible and determines the slot connection allocation request to the terminal device that has requested the slot connection allocation. Then, an allocation process is performed (S18).

  The above is the operation flow until the slot connection allocation process is performed. When it is determined that slot concatenation allocation is not possible (N in S12), or when it is determined that the reception level is lower than the first threshold (N in S16), the allocation determining unit 50 Normal slot allocation is performed for the terminal device that has requested slot connection allocation (S22). In normal slot allocation, a plurality of slots may be allocated on condition that a preamble is arranged in all slots.

  Next, a case where the allocation method is switched to normal slot allocation processing in the state where slot concatenation allocation is performed will be described. The assignment method switching determination described below may be performed at least once per frame, or may be performed irregularly. In determining whether to switch the allocation method, first, the traffic volume measuring unit 44 measures the traffic volume in the base station apparatus 10 notified via the processing unit 22. When this traffic volume is larger than the second threshold (Y in S20), the signal processing unit 40 causes the slot allocation unit 42 to forcibly stop execution of slot concatenation allocation in subsequent frames, Switch to normal slot allocation (S22). On the other hand, when the traffic becomes a value smaller than the second threshold (N in S20), the slot concatenation allocation is continued. At this time, by measuring again the reception level of the terminal device subject to slot concatenation allocation (S14), it is determined whether the resource can be released early, and then the slot concatenation allocation is continued (S16, S18). ).

  According to the embodiment of the present invention, it is possible to improve resource utilization efficiency by prohibiting slot connection allocation in response to an increase in communication volume. Further, although the communication efficiency for the preamble in the latter half slot is reduced, another terminal device can be assigned to another space in the latter half slot, so that the resource utilization efficiency can be improved. Further, if the slot concatenation assignment that is prohibited as the communication amount increases and then the communication amount decreases after that, the communication efficiency can be improved by allowing it again. Further, when switching the allocation method to slot concatenation allocation, resources can be released at an early stage by allowing higher-speed communication to a terminal device that newly performs slot continuous allocation. Furthermore, by allowing high-speed communication to the terminal device, resources can be released early. As a result, resource utilization efficiency can be improved and communication efficiency can be improved. Further, by assigning a terminal device having a high reception level to an unused resource, the unused resource can be effectively used. Also, by assigning a terminal device having a high reception level, resources can be released early, resource utilization efficiency can be improved, and communication efficiency can be improved. In addition, communication efficiency can be improved and resource utilization efficiency can be improved by preferentially performing slot concatenation allocation to terminal devices with high reception levels so that resources can be released early.

  The present invention has been described based on the embodiments. 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 slot allocation method performed by the base station apparatus 10 has been described as being switched according to the traffic. However, the present invention is not limited to this. For example, the communication method may be switched according to the location where the base station apparatus 10 is installed. For example, when the base station apparatus 10 is installed in an area where the average communication amount changes extremely with time, for example, in a bed town, the communication amount is considered to be small in the daytime. Just do it. Further, since there is a possibility that the amount of communication will increase at night, the switching operation as described above may be executed. Further, for example, when the base station apparatus 10 is installed in a sparsely populated area, it is considered that the communication volume is always low, and therefore, it may be set to always execute slot connection allocation.

It is a figure which shows the structural example of the base station apparatus which concerns on embodiment of this invention. FIGS. 2A and 2B are diagrams illustrating a configuration example of a frame assigned with a slot by the control unit. It is a figure which shows the structural example of the control part of FIG. It is a figure which shows the structural example of the slot allocation part of FIG. It is a flowchart which shows the operation example of the control part of FIG.

Explanation of symbols

  10 base station apparatus, 12 antenna, 20 radio section, 22 processing section, 24 modulation / demodulation section, 26 IF section, 30 control section, 32 management section, 40 signal processing section, 42 slot allocation section, 44 traffic volume measurement section, 50 allocation A determination unit; 52 an allocation confirmation unit; 54 a reception level measurement unit;

Claims (6)

A base station apparatus that uses a spatial multiplexing method to allocate communication slots to a plurality of terminal apparatuses so as to overlap in time,
For any one of the plurality of terminal devices, a preamble that overlaps in time with a preamble arranged in a communication slot assigned to another communication terminal is arranged only in the first slot. A slot allocation unit for allocating a plurality of consecutive communication slots;
A traffic measuring unit that measures the traffic between the plurality of terminal devices;
A signal processing unit that, when the communication amount measured by the communication amount measurement unit exceeds a threshold related to the communication amount, causes the slot allocation unit to arrange a preamble in each communication slot;
A base station apparatus comprising:   After the signal processing unit has arranged a preamble in each of the communication slots, if the communication amount measured by the communication amount measurement unit becomes smaller than a threshold related to the communication amount, the preamble is arranged only in the first slot. In addition, a terminal device that has been assigned a plurality of continuous communication slots is again assigned a plurality of continuous communication slots in which a preamble is arranged only in the first slot, and at the same time, the terminal device The base station apparatus according to claim 1, wherein execution of communication is allowed. The slot allocation unit
A reception level measurement unit that measures the reception level of the signal transmitted from the terminal device;
An assignment confirmation unit for confirming that a slot adjacent to the communication slot assigned to the terminal device is an empty slot;
When the reception level measured by the reception level measurement unit exceeds a threshold related to the reception level, a slot adjacent to the communication slot allocated to the terminal device by the allocation confirmation unit is an empty slot. When it is confirmed that there is an allocation determination unit that determines to allocate a plurality of continuous communication slots in which a preamble is arranged only in the first slot, to the terminal device;
The base station apparatus according to claim 1 or 2, characterized by comprising:   When there are a plurality of terminal devices in which the reception level measured by the reception level measurement unit exceeds a threshold related to the reception level, the allocation determination unit is a terminal having a higher reception level among the plurality of terminal devices. 4. The base station apparatus according to claim 3, wherein a plurality of continuous communication slots in which a preamble is arranged only in the head slot are preferentially assigned to the apparatus. An allocation method that assigns each communication slot so as to overlap in time with respect to a plurality of terminal devices using a spatial multiplexing method,
For any one of the plurality of terminal devices, a preamble that overlaps in time with a preamble arranged in a communication slot assigned to another communication terminal is arranged only in the first slot. Assigning a plurality of consecutive communication slots;
Measuring traffic between the plurality of terminal devices;
When the traffic measured by the measuring step exceeds a threshold related to the traffic, placing a preamble in each of the communication slots; and
The allocation method characterized by including. A program for assigning communication slots to a plurality of terminal devices so as to overlap in time using a spatial multiplexing method via a wireless network,
For any one of the plurality of terminal devices, a preamble that overlaps in time with a preamble arranged in a communication slot assigned to another communication terminal is arranged only in the first slot. Assigning a plurality of consecutive communication slots;
Measuring traffic between the plurality of terminal devices;
When the traffic measured by the measuring step exceeds a threshold related to the traffic, placing a preamble in each of the communication slots; and
A program that causes a computer to execute.

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