JP2018011189A - Base station device, radio communication system and base station device control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base station device which improves throughput in radio communications, a radio communication system and a base station device control method.SOLUTION: Based on whether a predetermined signal is transmitted in a specific radio resource, a coefficient calculation unit 153 sets priorities to allocate the specific radio resource to one or more first terminal devices each having a detection function for the predetermined signal and one or more second terminal devices each having no detection function. Based on the priorities that are set by the coefficient calculation unit 153, a resource allocation unit 151 allocates the specific radio resource to a terminal device belonging to any one of the first terminal devices and the second terminal devices. A radio processing unit 11 uses the specific radio resource to communicate with the terminal device to which the specific radio resource is allocated by the resource allocation unit 151.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a base station apparatus, a radio communication system, and a base station apparatus control method.

  In recent years, 3GPP (Third Generation Partnership Project) TSG (Technical Specification Group) RAN (Radio Access Network) Rel (Release). 10, CSI-RS (Channel State Information-Reference Signal) was defined. CSI-RS is a reference signal having the following characteristics and is mapped to a predetermined resource block.

  CSI-RS is an extension of Cell-specific RS capable of transmitting up to 4 antennas, and can transmit up to 8 antennas. CSI-RS is an RS for measuring CSI (CQI (Channel Quality Indicator) / PMI (Processing Matrix Indicator) / RI (Rank Indicator)), which is channel state information, and is transmitted once every 5 to 8 ms. Not used for estimation. In addition, 2 REs (Resource Elements) that are continuous in the time direction per antenna port are allocated to the CSI-RS, and beam forming is not applied. The CSI-RS considers that the CSI-RS is not transmitted when the following conditions are satisfied in a certain subframe. One of the conditions is a case where the subframe is a special subframe in the case of frame structure type2. Another one is a case where CSI-RS and SIB (System Information Block) collide. The other is a subframe in which the subframe is set so that a ping message is transmitted in a P (Primary) cell, and a unique ping is set in the P cell. It is. The other is a case where the subframe is a subframe in which a PSS (Primary Synchronization Signal) / SSS (Sub Synchronization Signal) / PBCH (Physical Broadcast Channel) and a CSI-RS transmission resource collide with each other.

  Here, unlike UE (User Equipment) -RS, in a subframe in which CSI-RS is transmitted, CSI-RS is transmitted in all resource blocks. In the standardization, it is defined that the PDSCH is not mapped to a resource element that is recognized not to be used for CSI-RS transmission by the terminal device. This means that the PDSCH (Physical Downlink Shared Channel) mapping method for the resource element to which CSI-RS is mapped changes according to the category of the terminal device as described below.

  In a resource block assigned to a terminal device that can interpret the mapping position of CSI-RS, PDSCH is not assigned to a resource element to which CSI-RS is mapped. In this case, PDSCH allocation is adjusted by rate matching or the like. Hereinafter, a terminal device that can read the CSI-RS mapping position is referred to as a “CSI-RS compatible terminal”, and a terminal device that cannot read the CSI-RS mapping position is referred to as a “CSI-RS non-compatible terminal”. "

  On the other hand, there is no particular rule in standardization for resource blocks allocated to CSI-RS non-compliant terminals. Therefore, even in a CSI-RS non-terminal device, a method in which PDSCH is not mapped to a resource element to be CSI-RS mapped is used in the same manner as a CSI-RS compatible terminal. Alternatively, a method of puncturing resource elements to which PDSCH is mapped and mapping CSI-RS is used.

  Note that, as a communication technique of a wireless communication system, when performing cooperative multipoint communication, scheduling is performed using the priority of the allocation candidate of the radio resource notified from the terminal device, thereby suppressing the calculation load and reducing the throughput. There are conventional techniques to improve the above. In addition, as a communication technique using CSI-RS, there is a conventional technique in which communication is performed by notifying a terminal device of resource element mapping of PDSCH when performing cooperative multipoint communication.

JP 2013-110671 A Japanese Patent Laying-Open No. 2015-92673

  However, as described above, it is difficult for a CSI-RS compatible terminal to determine whether or not CSI-RS is transmitted. For this reason, in the subframe in which CSI-RS is transmitted, the CSI-RS is overwritten on the resource element to which PDSCH can be originally allocated, and there is a possibility that throughput is deteriorated.

  In addition, even when the conventional technology that performs scheduling using the priority of the radio resource allocation candidate notified from the terminal apparatus is used, the CSI-RS may be overwritten on the resource element to which the PDSCH can be allocated. It is difficult to improve. Further, even when a conventional technique for notifying PDSCH resource element mapping is used, CSI-RS may be overwritten on a resource element to which PDSCH can be allocated, and it is difficult to improve throughput.

  The disclosed technique has been made in view of the above, and an object thereof is to provide a base station apparatus, a radio communication system, and a base station apparatus control method that improve throughput in radio communication.

  In one aspect of the base station apparatus, the radio communication system, and the base station apparatus control method disclosed in the present application, the priority setting unit determines whether the predetermined signal is transmitted based on whether a predetermined signal is transmitted in a specific radio resource. Each priority which allocates a specific radio | wireless resource with respect to the 1 or several 1st terminal device which has this detection function, and the 1 or several 2nd terminal device which does not have the said detection function is set. The resource allocation unit allocates the specific radio resource to a terminal device belonging to either the first terminal device or the second terminal device based on the priority set by the priority setting unit. The communication unit communicates with the terminal device to which the specific radio resource is allocated by the resource allocation unit, using the specific radio resource.

  According to one aspect of the base station apparatus, the radio communication system, and the base station apparatus control method disclosed in the present application, there is an effect that the throughput in the radio communication can be improved.

FIG. 1 is a configuration diagram illustrating an example of the overall configuration of a wireless communication system. FIG. 2 is a block diagram of the base station apparatus. FIG. 3 is a block diagram of the resource scheduler. FIG. 4 is a diagram illustrating a change in weighting factor for a CSI-RS non-compliant terminal apparatus in the base station apparatus according to the first embodiment. FIG. 5 is a flowchart of assignment of terminal devices to radio resources by the resource scheduler. FIG. 6 is a diagram of CSI-RS transmission interval setting information. FIG. 7 is a diagram illustrating the values of a and b according to the CSI-RS transmission interval. FIG. 8 is a diagram illustrating a change in weighting factor for a CSI-RS non-compliant terminal apparatus in the base station apparatus according to the second embodiment. FIG. 9 is a diagram for explaining a state of assignment of radio resources to terminal devices according to the second embodiment. FIG. 10 is a diagram illustrating a change in the weighting factor for BLER in the base station apparatus according to the third embodiment. FIG. 11 is a hardware configuration diagram of the base station apparatus.

  Hereinafter, embodiments of a base station apparatus, a wireless communication system, and a base station apparatus control method disclosed in the present application will be described in detail with reference to the drawings. The base station apparatus, the radio communication system, and the base station apparatus control method disclosed in the present application are not limited by the following embodiments.

  FIG. 1 is a configuration diagram illustrating an example of the overall configuration of a wireless communication system. As illustrated in FIG. 1, a wireless communication system 10 according to the present embodiment includes base station apparatuses 1 and 2, terminal apparatuses 3 and 4, and a core network 5.

  The core network 5 includes, for example, an MME (Mobility Management Entity) and an S-GW (Serving Gateway). The MME and S-GW arranged in the core network 5 are connected to the base station apparatuses 1 and 2 through the s1 interface.

  The base station apparatuses 1 and 2 are connected to the core network 5 through the s1 interface. Further, here, the base station apparatus 1 performs wireless communication with the terminal apparatus 3. Further, the base station device 2 performs wireless communication with the terminal device 4. Hereinafter, a case where there are a plurality of terminal apparatuses 3 that communicate with the base station apparatus 1 is collectively referred to as a terminal apparatus 3.

  The base station apparatus 1 transmits a signal addressed to the terminal apparatus 4 transmitted from the terminal apparatus 3 to the terminal apparatus 4 via the core network 5 and the base station apparatus 2, for example. Moreover, the base station apparatus 1 transmits a signal to which CSI-RS is mapped to the terminal apparatus 3. Furthermore, the base station apparatus 1 receives the data addressed to the terminal apparatus 3 transmitted from the terminal apparatus 4 via the base station apparatus 2 and the core network 5, and transmits the data to the terminal apparatus 3 using the PDSCH.

  Moreover, the base station apparatus 1 and the base station apparatus 2 are each connected by x2 interface. And the base station apparatus 1 and the base station apparatus 2 can communicate via x2 interface.

  Next, the base station apparatus 1 will be described in detail with reference to FIG. FIG. 2 is a block diagram of the base station apparatus. As illustrated in FIG. 2, the base station apparatus 1 includes a radio processing unit 11, a baseband processing unit 12, a network IF (Interface) unit 13, a resource scheduler 15, and an antenna 16. In the present embodiment, the base station apparatus 1 has a plurality of antennas 16.

  The network IF unit 13 is an interface in communication between the core network 5 and the base station device 2. In FIG. 2, connection with the core network 5 is illustrated as an example. The network IF unit 13 receives the signal transmitted from the terminal device 4 from the core network 5. Then, the network IF unit 13 outputs the received signal to the baseband processing unit 12.

  Further, the network IF unit 13 receives the signal transmitted from the terminal device 3 from the baseband processing unit 12. Then, the network IF unit 13 transmits the acquired signal to the core network 5.

  The baseband processing unit 12 performs signal processing on the baseband signal input from the wireless processing unit 11 or the network IF unit 13. The baseband processing unit 12 includes, for example, an encoding unit 121, a MAC (Media Access Control) multiplexed HARQ (Hybrid Automatic Repeat Request) unit 122, and an RLC (Radio Link Control) buffer 123. The baseband processing unit 12 includes a decoding unit 124 and a MAC separation unit 125.

  The RLC buffer 123 temporarily stores data to be transmitted to the terminal device 3. The RLC buffer 123 notifies the resource scheduler 15 when data to be transmitted is accumulated in the buffer.

  The MAC multiplexed HARQ unit 122 receives information on the transmission destination of data such as the terminal device 3 from the resource scheduler 15. Then, the MAC multiplexing HARQ unit 122 acquires data to be transmitted to the designated transmission destination from the RLC buffer 123. Then, the MAC multiplexing HARQ unit 122 applies the MAC multiplexing processing to the acquired data. Further, the MAC multiplexing HARQ unit 122 performs transmission processing according to the HARQ scheme. Thereafter, the MAC multiplexing HARQ unit 122 outputs the data to the encoding unit 121.

  The encoding unit 121 receives an input of data to be transmitted to the terminal device 3 from the MAC multiplexing HARQ unit 122. Also, the encoding unit 121 receives an input of the encoding rate from the resource scheduler 15. Then, the encoding unit 121 performs an encoding process on the acquired data. Thereafter, the encoding unit 121 outputs the data to the modulation unit 113 of the wireless processing unit 11.

  The decoding unit 124 receives an input of a signal transmitted from the terminal device 3 from the demodulation unit 114 of the wireless processing unit 11. Then, the decoding unit 124 performs a decoding process on the acquired signal. Thereafter, the decryption unit 124 outputs the data to the MAC separation unit 125.

  The MAC separation unit 125 receives data input from the decryption unit 124. Then, the MAC separation unit 125 performs a MAC separation process on the acquired data, and generates a signal to be transmitted to the terminal device 4. Thereafter, the MAC separation unit 125 transmits a signal to the terminal device 4 via the network IF unit 13 and the core network 5.

  The radio processing unit 11 includes a resource mapping unit 111, a precoding unit 112, a modulation unit 113, and a demodulation unit 114. The wireless processing unit 11 is an example of a “communication unit”.

  The modulation unit 113 receives data input from the encoding unit 121 of the baseband processing unit 12. Further, the modulation unit 113 receives an input of a data modulation scheme from the resource scheduler 15. Then, the modulation unit 113 modulates data by performing IFFT (Inverse Fast Fourier Transform) on the acquired signal. Modulation section 113 then outputs the signal generated by modulation to precoding section 112.

  The precoding unit 112 acquires information specifying a precoding matrix from the resource scheduler 15. For example, the precoding unit 112 receives from the resource scheduler 15 a PMI (Precoding Matrix Indicator) determined to be used for radio resources. Then, the precoding unit 112 specifies a precoding matrix using the acquired PMI.

  The precoding unit 112 receives an input of a signal to be transmitted from the modulation unit 113 to the terminal device 3 to which the radio resource for downlink communication is allocated by the resource scheduler 15. Then, the precoding unit 112 multiplies the acquired signal by a designated precoding matrix. Further, when transmitting the CSI-RS, the precoding unit 112 also multiplies the CSI-RS by a precoding matrix. Thereafter, precoding section 112 outputs a signal obtained by multiplying the precoding matrix to resource mapping section 111.

  The resource mapping unit 111 receives input of mapping information of downlink data and downlink control signals such as PDCCH (Physical Downlink Control Channel) transmitted on the PDSCH from the resource scheduler 15. Further, the resource mapping unit 111 receives input of mapping information of a reference signal such as CRS (Common Reference Signal) or CSI-RS from the resource scheduler 15.

  Then, the resource mapping unit 111 maps various signals to radio resources according to the mapping instructed by the resource scheduler 15. And the resource mapping part 111 transmits a signal to the terminal device 3 via the antenna 16 using the radio | wireless resource which mapped the signal.

  The demodulator 114 receives the signal transmitted from the terminal device 3 via the antenna 16. Then, the demodulation unit 114 performs FFT (Fast Fourier Transform) on the acquired signal and demodulates the signal. Then, the demodulation unit 114 outputs the data created by demodulating the signal to the decoding unit 124 of the baseband processing unit 12.

  The call control unit 14 acquires the call connection request transmitted from the terminal device 3 from the baseband processing unit 12. Then, the call control unit 14 controls the baseband processing unit 12 to perform a call connection procedure. The call control unit 14 manages the state of call connection for each terminal device 3. Thereafter, the call control unit 14 acquires the call disconnection request transmitted from the terminal device 3 or 4 from the baseband processing unit 12. Then, the call control unit 14 causes the baseband processing unit 12 to perform a procedure for disconnecting the call of the terminal device 3.

  The resource scheduler 15 acquires in advance the designation of the CSI-RS interval by an input from the operator. Further, the resource scheduler 15 has a formula for calculating a scheduling coefficient in advance. Further, the resource scheduler 15 includes a terminal device 3 having a function of detecting transmission of CSI-RS among the terminal devices 3 accommodated by the own device, that is, LTE (Long Term Evolution) Rel (Release). The number of CSI-RS compatible terminal devices that are 10 compatible terminal devices 3 is included. Further, the resource scheduler 15 includes, among the terminal devices 3 accommodated by the own device, the terminal device 3 that does not have a function of detecting transmission of CSI-RS, that is, LTE Rel. It has the number of CSI-RS non-corresponding terminal devices which are 8 or 9 compatible terminal devices 3. This CSI-RS is an example of a “predetermined signal”. This CSI-RS compatible terminal device is an example of a “first terminal device”. The CSI-RS non-compliant terminal device corresponds to an example of “second terminal device”.

  The resource scheduler 15 obtains the scheduling coefficient of each terminal device 3 accommodated by the own device using the number of CSI-RS compatible terminal devices and the number of non-CSI-RS compatible terminal devices. Then, for example, the resource scheduler 15 determines the terminal device 3 to which the radio resource in the subframe is allocated in descending order of the obtained scheduling coefficient. Here, in this embodiment, the resource scheduler 15 assigns radio resources in descending order of the scheduling coefficient, but the selection method of the terminal device 3 to which radio resources are assigned is not limited to this.

  Furthermore, the resource scheduler 15 determines a transmission format such as a data modulation scheme and a channel coding rate for the selected terminal apparatus 3, and a resource block.

  Thereafter, the resource scheduler 15 notifies the baseband processing unit 12 of information on the terminal device 3 to which radio resources are allocated, transmission format, resource block and data information. Further, the resource scheduler 15 includes information on the terminal device 3 to which radio resources are allocated, mapping information of downlink control signals such as downlink data and PDCCH transmitted by PDSCH, mapping information of reference signals such as CRS or CSI-RS, and Information on the precoding matrix is transmitted to the wireless processing unit 11.

  Next, with reference to FIG. 3, the selection function of the terminal device 3 to which the radio resource of the resource scheduler 15 is allocated will be described in more detail. FIG. 3 is a block diagram of the resource scheduler. As illustrated in FIG. 3, the resource scheduler 15 according to the present embodiment includes a resource allocation unit 151, a weight calculation unit 152, and a coefficient calculation unit 153.

  The resource allocation unit 151 includes CSI-RS interval information. And the resource allocation part 151 starts the process of the radio | wireless resource determination for every sub-frame. The resource allocation unit 151 determines whether or not the subframe for performing radio resource allocation is a subframe for transmitting CSI-RS. Then, the determination result is notified to the weight calculation unit 152. In addition, the resource allocation unit 151 instructs the coefficient calculation unit 153 to calculate the scheduling coefficient.

  Thereafter, the resource allocation unit 151 receives an input of the scheduling coefficient of each terminal device 3 accommodated by the own device from the coefficient calculation unit 153. Then, the resource allocation unit 151 selects the terminal devices 3 having the number of radio resources that can be allocated in descending order of the acquired scheduling coefficient. Further, the resource allocation unit 151 selects a transmission format and a resource block for the terminal device 3 to which the radio resource is allocated. Then, the resource allocation unit 151 notifies the radio processing unit 11 and the baseband processing unit 12.

  The weight calculation unit 152 stores in advance an expression for obtaining α that is a weighting coefficient for a CSI-RS non-compliant terminal device in the case of a subframe in which CSI-RS is transmitted. Further, the weight calculation unit 152 stores in advance an expression for obtaining β, which is a weighting coefficient for a CSI-RS non-compliant terminal device in the case of a subframe in which CSI-RS is not transmitted.

  For example, in this embodiment, the weight calculation unit 152 stores the following (Equation 1) as an equation for obtaining α and β.

Here, n _A is the number of CSI-RS compatible terminal devices accommodated by the own device. Further, _{n B} is the number of CSI-RS incompatible terminal device when the device itself housed. K is a proportional coefficient, and is determined by computer simulation, for example.

  Then, the weight calculation unit 152 receives, from the resource allocation unit 151, information on whether or not the subframe is a subframe for transmitting CSI-RS for each subframe. Furthermore, the weight calculation unit 152 acquires the number of CSI-RS compatible terminal devices accommodated by the own device and the number of CSI-RS non-compliant terminal devices accommodated by the own device from the call control unit 14.

  And the weight calculation part 152 calculates (alpha), when the sub-frame which allocates a radio | wireless resource is a sub-frame which transmits CSI-RS. Then, the weight calculation unit 152 transmits the value of α calculated as the weight coefficient for the CSI-RS non-compliant terminal device to the coefficient calculation unit 153. In addition, when the subframe to which the radio resource is allocated is a subframe in which CSI-RS is transmitted, β is calculated. Then, the weight calculation unit 152 transmits the value of β calculated as the weight coefficient for the CSI-RS non-compliant terminal device to the coefficient calculation unit 153.

Here, the relationship between the terminal device number ratio and α and β will be described with reference to FIG. FIG. 4 is a diagram illustrating a change in weighting factor for a CSI-RS non-compliant terminal apparatus in the base station apparatus according to the first embodiment. In this case, k = 0.1. In FIG. 4, the vertical axis represents the values of α and β, and the horizontal axis represents the ratio of the number of terminal devices. The terminal device number ratio is a value obtained by dividing the number n _A of CSI-RS compatible terminal devices by the number n _B of non-CSI-RS compatible terminal devices. Hereinafter, a subframe to which radio resources are allocated may be referred to as a “target subframe”.

  In the case where the target subframe is a subframe that transmits CSI-RS, when the radio resource of the target subframe is assigned to a terminal device that does not support CSI-RS, communication of the terminal device that does not support CSI-RS deteriorates. Therefore, it is preferable that assignment of radio resources of subframes for transmitting CSI-RS to terminal devices that do not support CSI-RS is suppressed.

  When the number of CSI-RS non-compliant terminal devices is very small compared to the number of CSI-RS compatible terminal devices, the probability that the radio resource of the target subframe is allocated to the CSI-RS non-compliant terminal device is small. Therefore, when the number of CSI-RS non-compliant terminal devices is very small compared to the number of CSI-RS non-compliant terminal devices, the influence of weight adjustment on the scheduling coefficient of the CSI-RS non-compliant terminal devices should be reduced. Is preferred. This is the same whether the target subframe is a subframe that transmits CSI-RS or a subframe that does not transmit CSI-RS. That is, when the number of CSI-RS incompatible terminal devices is very small as compared with the number of CSI-RS compatible terminal devices, both α and β are preferably close to 1.

  On the other hand, as the number of CSI-RS incompatible terminal devices becomes larger than the number of CSI-RS compatible terminal devices, the probability that the target subframe is allocated to the CSI-RS incompatible terminal devices increases. . That is, when the target subframe is a subframe that transmits CSI-RS, the number of CSI-RS incompatible terminal devices increases as compared to the CSI-RS compatible terminal devices, and the CSI-RS incompatible terminal devices Is preferably difficult to assign. In addition, when the target subframe is not a subframe for transmitting CSI-RS, as the number of CSI-RS non-compliant terminal devices increases compared to the CSI-RS compatible terminal device, the target subframe is not included in the CSI-RS non-compliant terminal device. Is preferably not easily assigned. That is, as the number of CSI-RS non-compliant terminal devices becomes larger than the number of CSI-RS compatible terminal devices, α is preferably close to 0, and β is preferably large and away from 1.

  In this regard, as described above, when α and β are values represented by (Equation 1), α and β have the relationship shown in FIG. 4 with respect to the terminal device number ratio. An increase in the terminal device number ratio indicates that the number of CSI-RS non-compatible terminal devices is smaller than the number of CSI-RS compatible terminal devices. Conversely, a decrease in the terminal device number ratio indicates that the number of CSI-RS non-compatible terminal devices is larger than the number of CSI-RS compatible terminal devices. That is, a change in α according to the proportion of terminal devices not compatible with CSI-RS is represented by a graph 201, and a change in β according to the proportion of terminal devices not compatible with CSI-RS is represented by a graph 202. The From the graphs 201 and 202, it can be said that α and β calculated by the weight calculation unit 152 according to the present embodiment satisfy the above-described relationship. As described above, an appropriate weight is given to the scheduling coefficient of the CSI-RS non-compliant terminal device by α and β calculated by the weight calculation unit 152 according to the present embodiment.

The coefficient calculation unit 153 stores a calculation formula for Cn, which is a scheduling coefficient, in advance. For example, the coefficient calculation unit 153 calculates Cn by dividing the instantaneous throughput of each terminal apparatus 3 by the average throughput and multiplying the buffer retention amount, the number of retransmissions, and the like as a calculation expression for Cn that is a scheduling coefficient. Remember. For example, the equation stored in the coefficient calculation unit 153 is expressed as “Cn = R _inst / R _ave × p × q ×. Here, R _inst represents the instantaneous throughput of each terminal apparatus 3, R _ave represents the average value of the throughput of each terminal apparatus 3 in a predetermined period, p represents the buffer retention amount, and q represents the number of retransmissions. The scheduling coefficient Cn is preferably determined so as to maintain fairness without depending on whether the communication quality is good or bad so that radio resources are not allocated to specific terminal devices 3. Therefore, the coefficient calculation unit 153 may use other values for calculation of Cn that is a scheduling coefficient as long as the value maintains fairness, and may use, for example, a data retention time.

  The coefficient calculation unit 153 receives an instruction to calculate a scheduling coefficient from the resource allocation unit 151. Then, the coefficient calculation unit 153 acquires information about the buffer retention amount and the data retention time from the baseband processing unit 12. Further, the coefficient calculation unit 153 obtains information about which terminal device 3 is made to transmit data for each subframe from the resource allocation unit 151, and calculates an instantaneous throughput and an average value of the throughput for a predetermined time. And the coefficient calculation part 153 calculates the scheduling coefficient Cn for every terminal device 3 which the own apparatus accommodates.

  Next, the coefficient calculation unit 153 receives an input of the value of α or β as a weighting coefficient for the CSI-RS non-compliant terminal apparatus from the weight calculation unit 152. And the coefficient calculation part 153 multiplies the weighting coefficient with respect to a CSI-RS non-corresponding terminal apparatus by the calculated scheduling coefficient Cn of each CSI-RS non-corresponding terminal apparatus, and calculates the scheduling coefficient Cn of each CSI-RS non-corresponding terminal apparatus. Recalculate. Thereafter, the coefficient calculation unit 153 notifies the resource allocation unit 151 of the calculated scheduling coefficient Cn of each terminal apparatus 3 accommodated by the own apparatus. The weight calculation unit 152 and the coefficient calculation unit 153 correspond to an example of a “priority setting unit”. The scheduling coefficient Cn of each terminal device 3 corresponds to an example of “priority”.

  Here, with reference to FIG. 5, the flow of allocation of the terminal device 3 to the radio resource by the resource scheduler 15 will be described. FIG. 5 is a flowchart of assignment of terminal devices to radio resources by the resource scheduler.

  For each subframe, the coefficient calculation unit 153 calculates a scheduling coefficient Cn for each terminal apparatus 3 accommodated by the own apparatus (step S1).

  Next, the resource allocation unit 151 determines whether or not a subframe to which radio resources are allocated is a subframe for transmitting CSI-RS, that is, whether or not to perform CSI-RS transmission in the subframe ( Step S2).

  In the case of a subframe for transmitting CSI-RS (step S2: affirmative), the resource allocation unit 151 notifies the weight calculation unit 152 that it is a subframe for transmitting CSI-RS. In response to the notification from the resource allocation unit 151, the weight calculation unit 152 calculates α, which is a weight coefficient of a CSI-RS non-compliant terminal device in a subframe in which CSI-RS is transmitted (step S3). Next, the weight calculation unit 152 notifies the coefficient calculation unit 153 of the calculated weight coefficient α of the CSI-RS non-compliant terminal apparatus.

  On the other hand, if it is not a subframe for transmitting CSI-RS (No at Step S2), resource allocation section 151 notifies weight calculation section 152 that it is not a subframe for transmitting CSI-RS. In response to the notification from the resource allocation unit 151, the weight calculation unit 152 calculates β, which is a weight coefficient of a CSI-RS non-compliant terminal device in a subframe in which CSI-RS is not transmitted (step S4). Next, the weight calculation unit 152 notifies the coefficient calculation unit 153 of the calculated weight coefficient β of the CSI-RS non-compliant terminal device.

  The coefficient calculation unit 153 multiplies the calculated scheduling coefficient Cn of each CSI-RS non-compliant terminal apparatus by the weight coefficient of the CSI-RS non-compliant terminal apparatus, and calculates the calculated scheduling coefficient Cn of each CSI-RS non-compliant terminal apparatus. Recalculation is performed (step S5). Next, the coefficient calculation unit 153 notifies the resource allocation unit 151 of the scheduling coefficient Cn of each terminal device 3. The resource allocation unit 151 selects the terminal device 3 to which the radio resource is allocated, using the scheduling coefficient Cn of each terminal device 3 notified from the coefficient calculation unit 153 (step S6).

  Further, the resource allocation unit 151 performs TFR (Transport Format and Resource) selection for selecting a transmission format and a resource block (step S7). Thereafter, the resource allocation unit 151 notifies the radio processing unit 11 and the baseband processing unit 12 of information such as the terminal device 3 to which the radio resource is allocated and the selected transmission format and resource block.

  As described above, the base station apparatus according to the present embodiment determines the terminal apparatus to which radio resources are allocated by changing the scheduling coefficient of the CSI-incompatible terminal apparatus according to the ratio of the CSI-RS incompatible terminal apparatus. To do. Thereby, allocation of the radio | wireless resource of the sub-frame which transmits CSI-RS with respect to a CSI-RS non-terminal device can be suppressed, and deterioration of the communication quality of a CSI-RS non-terminal device can be reduced. Furthermore, the throughput in wireless communication can be improved.

  Next, Example 2 will be described. The base station apparatus which concerns on a present Example calculates | requires the weighting coefficient of a CSI-RS non-corresponding | compatible terminal apparatus using the transmission interval of CSI-RS. The base station apparatus and resource scheduler according to the present embodiment are also shown in FIGS. In the following description, the description of the operation of each part similar to that of the first embodiment is omitted.

  The resource allocation unit 151 has a CSI-RS transmission interval in advance. Specifically, the resource allocation unit 151 obtains the CSI-RS transmission interval from the CSI-RS subframe setting value input from the operator.

Here, FIG. 6 is a diagram of CSI-RS transmission interval setting information. As shown in CSI-RS transmission interval setting table 301, in response to the _{I CSI-RS} is a sub-frame set value of CSI-RS, _{T CSI-RS} is the period of the subframe transmitting the CSI-RS is determined The That is, the resource allocation unit 151 receives an input of I _CSI-RS that is a CSI-RS subframe setting value input from the operator, and determines the CSI-RS from the correspondence relationship indicated in the CSI-RS transmission interval setting table 301. _TCSI-RS which is the period of the subframe which transmits RS is _{calculated |} required. Here, the period of the subframe for transmitting the CSI-RS indicates how many subframes for transmitting the CSI-RS are generated. For example, when I _CSI-RS is set to 0, the resource allocation unit 151 determines to arrange a subframe for transmitting the CSI-RS every 5 subframes as a transmission interval of the CSI-RS.

  Then, the resource allocation unit 151 notifies the weight calculation unit 152 of information on the CSI-RS transmission interval together with the determination result of whether or not the subframe to which radio resources are allocated is a subframe for transmitting CSI-RS.

  The weight calculation unit 152 stores in advance an expression for obtaining α, which is a weighting factor for a CSI-RS non-compliant terminal apparatus in the case of a subframe transmitting CSI-RS, according to the CSI-RS transmission interval. Moreover, the weight calculation part 152 memorize | stores beforehand the formula which calculates | requires (beta) which is a weighting coefficient with respect to a CSI-RS non-corresponding | compatible terminal apparatus in the case of the sub-frame which does not transmit CSI-RS according to a CSI-RS transmission interval.

  For example, in this embodiment, the weight calculation unit 152 stores the following (Equation 2) as an equation for obtaining α and β.

Here, a and b are coefficients according to the transmission interval of CSI-RS. These a and b are obtained by the following method, for example. In this embodiment, the weight calculation unit 152 has a table 302 as shown in FIG. FIG. 7 is a diagram illustrating the values of a and b according to the CSI-RS transmission interval. The CSI-RS transmission interval is _TCSI-RS in FIG. The weight calculation unit 151 determines a and b using this table 320. For example, when the CSI-RS transmission interval is 5, the weight calculation unit 152 sets a = 1 and b = 4.

  For each subframe, the weight calculation unit 152 receives, from the resource allocation unit 151, information on whether or not the subframe is a subframe that transmits CSI-RS. Further, the weight calculation unit 152 receives an input of CSI-RS transmission interval information from the resource allocation unit 151.

  And the weight calculation part 152 calculates (alpha), when the sub-frame which allocates a radio | wireless resource is a sub-frame which transmits CSI-RS. Then, the weight calculation unit 152 transmits the value of α calculated as the weight coefficient for the CSI-RS non-compliant terminal device to the coefficient calculation unit 153. In addition, when the subframe to which the radio resource is allocated is a subframe in which CSI-RS is transmitted, β is calculated. Then, the weight calculation unit 152 transmits the value of β calculated as the weight coefficient for the CSI-RS non-compliant terminal device to the coefficient calculation unit 153.

  Here, the relationship between the CSI-RS transmission interval and α and β will be described with reference to FIG. FIG. 8 is a diagram illustrating a change in weighting factor for a CSI-RS non-compliant terminal apparatus in the base station apparatus according to the second embodiment. In this case, k = 1. In FIG. 8, the vertical axis represents the values of α and β, and the horizontal axis represents the CSI-RS transmission interval.

  When the CSI-RS transmission interval is long, the probability that the radio resource of the subframe that transmits the CSI-RS is allocated to the CSI-RS non-compliant terminal device is small. Therefore, when the CSI-RS transmission interval is long, it is preferable to reduce the influence of the adjustment due to the weight on the scheduling coefficient of the terminal device that does not support CSI-RS. This is the same whether the target subframe is a subframe that transmits CSI-RS or a subframe that does not transmit CSI-RS. That is, when the CSI-RS transmission interval is long, both α and β are preferably close to 1.

  On the other hand, as the CSI-RS transmission interval becomes shorter, the probability that a subframe for transmitting CSI-RS is allocated to a CSI-RS non-compliant terminal device increases. That is, when the target subframe is a subframe in which CSI-RS is transmitted, it is preferable that the target subframe is less likely to be assigned to a CSI-RS non-compliant terminal device as the CSI-RS transmission interval becomes shorter. In addition, when the target subframe is not a subframe for transmitting CSI-RS, it is preferable that the target subframe is less likely to be allocated to a CSI-RS non-compliant terminal device as the CSI-RS transmission interval becomes shorter. That is, as the CSI-RS transmission interval becomes shorter, it is preferable that α approaches 0, and β becomes larger and away from 1.

  As described above, when α and β are values represented by (Expression 2), α and β have the relationship shown in FIG. 8 with respect to the CSI-RS transmission interval. That is, a change in α according to the CSI-RS transmission interval is represented by a graph 211, and a change in β according to the CSI-RS transmission interval is represented by a graph 212. From the graphs 211 and 212, it can be said that α and β calculated by the weight calculation unit 152 according to the present embodiment satisfy the above-described relationship. As described above, an appropriate weight is given to the scheduling coefficient of the CSI-RS non-compliant terminal device by α and β calculated by the weight calculation unit 152 according to the present embodiment.

FIG. 9 is a diagram for explaining a state of assignment of radio resources to terminal devices according to the second embodiment. FIG. 9 shows a state in which subframes are arranged. In FIG. 9, subframes # 0 to # 15 are arranged. In this case, I _CSI-RS is 0, that is, as a CSI-RS transmission interval, a subframe for transmitting CSI-RS is arranged every five subframes.

  For example, when the subframes 311 to 314 are subframes for transmitting CSI-RS, CSI-RS compatible terminals are preferentially assigned to the subframes 311 to 314. In contrast, CSI-RS non-compliant terminals are preferentially assigned to subframes other than the subframes 311 to 314.

  As described above, the base station apparatus according to the present embodiment changes the scheduling coefficient of the CSI-RS non-compliant terminal apparatus according to the CSI-RS transmission interval, and determines a terminal apparatus to which radio resources are allocated. Thereby, allocation of the radio | wireless resource of the sub-frame which transmits CSI-RS with respect to a CSI-RS non-terminal device can be suppressed, and deterioration of the communication quality of a CSI-RS non-terminal device can be reduced. Furthermore, the throughput in wireless communication can be improved.

  Next, Example 3 will be described. The base station apparatus which concerns on a present Example calculates | requires the weighting coefficient of a CSI-RS non-corresponding terminal device using the reception quality of a CSI-RS non-corresponding terminal device. The base station apparatus and resource scheduler according to the present embodiment are also shown in FIGS. In the following description, the description of the operation of each part similar to that of the first embodiment is omitted. Here, a case where BLER (Block Error Rate) is used as reception quality will be described. BLER is the ratio between the total number of transport blocks in a certain period and the number of transport blocks in error.

  The resource allocation unit 151 acquires the CQI (Channel Quality Indicator) of the resource block in the subframe allocated to the terminal device 3 from the baseband processing unit 12. The CQI of the resource block is fed back from the terminal device 3 to which the resource block is assigned. Then, the resource allocation unit 151 performs MCS (Modulation and Coding Scheme) selection using the CQI of the resource block, and selects a modulation and decoding scheme. Further, the resource allocation unit 151 performs control so that the BLER approaches the BLER target value by correcting the fed back CQI.

  Then, for each subframe, the resource allocation unit 151 includes, as information on whether or not the subframe is a subframe for transmitting CSI-RS, the weight calculation unit using the latest BLER of each terminal device 3 as the BLER in the subframe. It outputs to 152.

  The weight calculation unit 152 stores in advance an expression for obtaining α, which is a weighting coefficient for a CSI-RS non-compliant terminal device in the case of a subframe transmitting CSI-RS, according to the reception quality of the CSI-RS non-compliant terminal device. To do. In addition, the weight calculation unit 152 obtains an equation for obtaining β, which is a weighting coefficient for a CSI-RS non-compliant terminal device in the case of a subframe that does not transmit CSI-RS, according to the reception quality of the CSI-RS non-compliant terminal device. Store in advance.

For example, in the present embodiment, the weight calculation unit 152 stores the equations for obtaining α and β as the following (Equation 3) divided into the case of BLER _inst > BLER _{target and} the case of BLER _inst ≦ BLER _target .

Here, BLER _inst is the BLER in the subframe. BLER _target is a target value of BLER. M is a proportional coefficient, and is determined by computer simulation, for example. N is a coefficient and is determined by computer simulation, for example.

  Then, the weight calculation unit 152 receives, from the resource allocation unit 151, information on whether or not the subframe is a subframe for transmitting CSI-RS for each subframe. Further, the weight calculation unit 152 receives the latest BLER input of each terminal apparatus 3 from the resource allocation unit 151 as the BLER in the subframe.

  When the subframe to which the radio resource is allocated is a subframe in which CSI-RS is transmitted, the weight calculation unit 152 calculates α. Then, the weight calculation unit 152 transmits the value of α calculated as the weighting factor for the terminal device that does not support CSI-RS to the coefficient calculation unit 153. In addition, when the subframe to which the radio resource is allocated is a subframe in which CSI-RS is transmitted, β is calculated. Then, the weight calculation unit 152 transmits the value of β calculated as the weight coefficient for the CSI-RS non-compliant terminal device to the coefficient calculation unit 153.

Here, the relationship between BLER and α and β will be described with reference to FIG. FIG. 10 is a diagram illustrating a change in the weighting factor for BLER in the base station apparatus according to the third embodiment. In this case, BLER _target = 1, m = 1, and n = 2. In FIG. 10, the vertical axis represents the values of α and β, and the horizontal axis represents BLER _inst .

When BLER _inst is lower than BLER _target , the reception quality of the CSI-RS non-compliant terminal device is high. Therefore, sufficient communication quality can be obtained by assigning radio resources of subframes that do not transmit CSI-RS to terminal devices that do not support CSI-RS. Therefore, when the BLER _inst is low, it is preferable to reduce the influence of the adjustment due to the weight on the scheduling coefficient of the terminal device that does not support CSI-RS. This is the same whether the target subframe is a subframe that transmits CSI-RS or a subframe that does not transmit CSI-RS. That is, when BLER _inst is low, both α and β are preferably close to 1.

On the other hand, as the BLER _inst becomes higher than the BLER _target , the reception quality of the CSI-RS non-compliant terminal apparatus decreases. In this state, if a subframe for transmitting a CSI-RS is allocated to a CSI-RS non-compliant terminal device, the reception quality of the CSI-RS non-compliant terminal device is further deteriorated. On the other hand, if a subframe that does not transmit CSI-RS is allocated to a terminal device that does not support CSI-RS, it can be expected that reception quality of the terminal device that does not support CSI-RS is improved.

Therefore, when the target subframe is a subframe that transmits CSI-RS, it is preferable that the target subframe is not easily assigned to a terminal device that does not support CSI-RS as BLER _inst becomes higher than BLER _target . Further, when the target subframe is not a subframe for transmitting CSI-RS, it is preferable that the target subframe is not easily assigned to a CSI-RS non-compliant terminal device as BLER _inst becomes higher than BLER _target . That is, as BLER _inst becomes higher than BLER _target , α preferably approaches 0, and β becomes larger and away from 1.

When α and β are values represented by (Equation 3), α and β have the relationship shown in FIG. 10 with respect to the CSI-RS transmission interval. That is, a change in α according to BLER _inst is represented by a graph 221, and a change in β according to BLER _inst is represented by a graph 222. From the graphs 221 and 222, it can be said that α and β calculated by the weight calculation unit 152 according to the present embodiment satisfy the above-described relationship. As described above, an appropriate weight is given to the scheduling coefficient of the CSI-RS non-compliant terminal device by α and β calculated by the weight calculation unit 152 according to the present embodiment.

  As described above, the base station apparatus according to the present embodiment changes the scheduling coefficient of the CSI-RS non-compliant terminal apparatus according to the reception quality of the CSI-RS non-compliant terminal apparatus, and allocates the radio resource to the terminal apparatus. decide. Thereby, allocation of the radio | wireless resource of the sub-frame which transmits CSI-RS with respect to a CSI-RS non-terminal device can be suppressed, and deterioration of the communication quality of a CSI-RS non-terminal device can be reduced. Furthermore, the throughput in wireless communication can be improved.

  Here, in each of the embodiments described above, α and a weighting coefficient for a CSI-RS non-compliant terminal apparatus in the case where the target subframe is a subframe in which CSI-RS is transmitted and the subframe in which CSI-RS is not transmitted. Several methods for calculating β have been described. However, the calculation method of (alpha) and (beta) is not restricted to this, You may use another method. For example, a table of α and β may be created using computer simulation or the like, and α and β may be obtained using the table. Further, for example, when the target subframe is a subframe that transmits CSI-RS, radio resources may not be allocated to a CSI-RS non-compliant terminal apparatus.

(Hardware configuration)
Next, a hardware configuration of the base station apparatus 1 according to each embodiment will be described with reference to FIG. FIG. 11 is a hardware configuration diagram of the base station apparatus.

  As shown in FIG. 11, the base station apparatus 1 includes a memory 91, a CPU (Central Processing Unit) 92, DSPs (Digital Signal Processors) 93 to 95, an accelerator 96, an amplifier 7, a network interface 98, and an antenna 16.

  The CPU 92, the DSPs 93 to 95, the memory 91, the accelerator 96, and the network interface 98 are connected to each other by a bus. The accelerator 96 is connected to the amplifier 97. The amplifier 97 is connected to the antenna 16.

  The network interface 98 implements the function of the network IF unit 13 illustrated in FIG.

  The memory 91 includes various programs including programs for realizing the wireless processing unit 11, the baseband processing unit 12, the call control unit 14, and the resource scheduler 15 illustrated in FIG.

  The CPU 92 implements the functions of the call control unit 14 and the resource scheduler 15 illustrated in FIG. 1 by reading out various programs from the memory 91 and developing and executing them.

  The DSP 94 implements the functions of the MAC multiplexing HARQ unit 122 and the MAC separation unit 125 illustrated in FIG. 1 by reading out various programs from the memory 91, developing them, and executing them.

  The DSP 93 implements the functions of the encoding unit 121 and the decoding unit 124 illustrated in FIG. 1 by reading out various programs from the memory 91, developing them, and executing them.

  The DSP 95 implements the functions of the modulation unit 113, the demodulation unit 114, and the precoding unit 112 illustrated in FIG. 1 by reading out various programs from the memory 91, developing them, and executing them. The DSP 95 may be an accelerator.

  The accelerator 96 implements IFFT and the function of the resource mapping unit 111 illustrated in FIG. 1 by reading various programs from the memory 91 and developing and executing them. The signal output from the accelerator 96 is amplified by the amplifier 97 and transmitted to the terminal device 3 via the antenna 16.

DESCRIPTION OF SYMBOLS 1, 2 Base station apparatus 3,4 Terminal apparatus 5 Core network 10 Wireless communication system 11 Wireless processing part 12 Baseband processing part 13 Network IF part 14 Call control part 15 Resource scheduler 16 Antenna 111 Resource mapping part 112 Precoding part 113 Modulation Unit 114 demodulating unit 121 encoding unit 122 MAC multiplexed HARQ unit 123 RLC buffer 124 decoding unit 125 MAC separation unit 151 resource allocation unit 152 weight calculation unit 153 coefficient calculation unit

Claims (7)

Based on whether or not a predetermined signal is transmitted in a specific radio resource, one or a plurality of first terminal devices having a detection function of the predetermined signal and one or a plurality of second terminals having no detection function A priority setting unit for setting respective priorities for allocating the specific radio resource to the terminal device;
A resource allocation unit that allocates the specific radio resource to a terminal device belonging to either the first terminal device or the second terminal device based on the priority set by the priority setting unit;
A base station apparatus comprising: a communication unit that communicates with the terminal device to which the specific radio resource is allocated by the resource allocation unit using the specific radio resource.   In the case of a radio resource to which the predetermined signal is transmitted, the priority setting unit sets the priority of the first terminal device higher than the priority of the second terminal device and does not transmit the predetermined signal. 2. The base station apparatus according to claim 1, wherein the priority of the first terminal apparatus is made lower than the priority of the second terminal apparatus.   The base station according to claim 1 or 2, wherein the priority setting unit sets the priority based on a ratio between the number of the first terminal devices and the number of the second terminal devices. apparatus.   The base station apparatus according to claim 1, wherein the priority setting unit sets the priority based on a transmission interval of the predetermined signal.   The base station apparatus according to claim 1 or 2, wherein the priority setting unit sets the priority based on reception quality of the second terminal apparatus. A wireless communication system having one or more first terminal devices having a predetermined signal detection function, one or more second terminal devices not having the detection function, and a base station device,
The base station device
A priority setting unit configured to set respective priorities for allocating the specific radio resource to the first terminal device and the second terminal device based on whether the predetermined signal is transmitted in the specific radio resource; ,
A resource allocation unit that allocates the radio resource to any one of the first terminal device and the second terminal device based on the priority set by the priority setting unit;
A radio communication system, comprising: a communication unit that communicates with the terminal device to which the radio resource is allocated by the resource allocation unit using the radio resource. In the base station device,
Based on whether or not a predetermined signal is transmitted in a specific radio resource, one or a plurality of first terminal devices having a detection function of the predetermined signal and one or a plurality of second terminals having no detection function For each of the terminal devices, the priority for allocating the specific radio resource is set,
Based on the set priority, the radio resource is allocated to either the first terminal device or the second terminal device,
A base station apparatus control method characterized by causing communication with the terminal apparatus to which the radio resource is allocated using the allocated radio resource.

Images