JP6421097B2 - Reception device, reception method, wireless communication system, and wireless communication method - Google Patents

Description

The present invention relates to a receiving apparatus, a receiving method , a wireless communication system, and a wireless communication method that perform wireless communication in a wireless environment in which an interference signal exists.

  In recent years, due to diversification of wireless communication services, there are mobile communication terminals such as smart phones and wireless LAN (Local Area Network) devices such as wireless LAN (Local Area Network) devices that perform wireless communication using various wireless communication methods. In a wireless communication system that uses signals that are radio waves of the same modulation method in the same frequency band, the number of transmission devices and reception devices increases, so that the reception device receives signals from transmission devices that perform wireless communication (hereinafter referred to as communication). And a signal from another transmitting apparatus (hereinafter also referred to as an interference signal). For this reason, the probability that interference will occur between the communication signal and the interference signal in the receiving apparatus may increase, and the frequency utilization efficiency may deteriorate.

  For example, the receiving apparatus sequentially demodulates from the signal indicating the maximum received power among the received signals using SIC (Successive Interference Cancellation), and the received signal is an interference signal. There has been proposed a technique for demodulating a communication signal by removing an interference signal from (see, for example, Non-Patent Document 1).

  FIG. 6 shows an example of wireless communication using SIC.

  In FIG. 6, for example, the transmission device Ta transmits a communication signal addressed to the reception device Ra, and the transmission device Tb transmits a communication signal addressed to the reception device Rb in the same modulation scheme as the transmission device Ta. Each receiving device Ra, Rb receives a communication signal addressed to the local station as well as a communication signal addressed to the other station as an interference signal. Then, the receiving devices Ra and Rb demodulate the signal having the highest received power. For example, when the power of the signal 1 indicating the communication signal addressed to the receiving device Ra is larger than the power of the signal 2 indicating the communication signal addressed to the receiving device Rb, the receiving device Ra demodulates the signal 1 having the highest received power, The reception process ends.

  On the other hand, since the demodulated signal with the highest received power is the signal 1, the receiving device Rb recalculates the signal in the radio section from the demodulated signal using the SIC technique to generate a replica signal of the signal 1, The signal 1 is removed by subtracting the signal. The receiving device Rb demodulates the signal 2 having the next highest received power among the received signals from which the signal 1 has been removed, and ends the receiving process. When three or more signals are superimposed, the signal addressed to the own station can be demodulated by repeatedly executing the SIC technique.

Souvik Sen et al., “Successive interference cancellation: a back-of-the-envelope perspective”, 9th ACM SIGCOMM Workshop on Hot Topics in Networks, Article No. 17, 2010

  For example, as illustrated in FIG. 7, if there is no sufficient power difference between the signals 1 and 2 from the received transmission devices Ta and Tb, the reception device Ra cannot receive the signal 1 using the SIC technique. Communication quality will be degraded. In the case of FIG. 7, in the receiving device Ra, the signal 2 from the transmitting device Tb becomes an interference signal, and the signal 1 transmitted from the transmitting device Ta cannot be normally received and demodulated.

  Further, the throughput of the entire wireless communication system depends on the power of the received signal at each receiving device (that is, the positional relationship with the transmitting device and the power of the signal transmitted by each transmitting device). For this reason, as shown in FIG. 7, when the probability that wireless communication fails will increase, the throughput of the entire wireless communication system will decrease.

An object of the present invention is to provide a receiving apparatus, a receiving method , a wireless communication system, and a wireless communication method capable of improving throughput in a wireless environment where an interference signal exists.

1st invention measures the reception power of the receiving part which receives the signal transmitted with the same frequency and the same modulation system from each of a plurality of transmitting devices, and the reception power of the received signal which the receiving part received, and performs the successive interference cancellation method A demodulation unit that demodulates a communication signal that is a signal transmitted by a transmission device that performs wireless communication among received signals, and causes a plurality of transmission devices to adjust transmission power based on reception power measured by the demodulation unit A control unit that outputs a control signal including an instruction.

Then, control section and all of the signal reception power from the communication signal is large and the communication signal processed, for each of the processing target signal, and the received power of the processed signal, signal to be processed includes a calculation unit for calculating a ratio of the total value of the received power of all signals received power is small Ri good, with each of the processed signal, if the ratio calculating unit has calculated is less than the predetermined value, as the ratio is greater than or equal to a predetermined value, transmitting apparatus for transmitting a control signal or signals received power from the signal to be processed is small, including the instruction to increase the transmission power to the transmitter for transmitting a signal to be processed A control signal including an instruction to reduce transmission power is output.

A second invention is a wireless communication system comprising a plurality of transmission devices and the reception device of the first invention, wherein each of the transmission devices transmits a signal at the same frequency and the same modulation scheme as the other transmission devices. When a receiving unit of the transmitting apparatus side that receives a control signal including an instruction to adjust the transmission power of a signal transmitted from the receiving apparatus, and based on the instructions contained in the received control signal, the signal transmitting unit transmits A transmission control unit for controlling transmission power .

In the second invention, the transmission control unit, when receiving the control signals from the plurality of receiving devices, based on the number of received instructions for each content and the content of the instruction included in each of the received control signal, transmitting unit adjusts the transmission power of a signal to be transmitted.

According to a third aspect of the present invention, there is provided a reception step of receiving a signal transmitted from each of a plurality of transmission apparatuses with the same frequency and the same modulation scheme, and a reception power of the reception signal received in the reception step, and a successive interference cancellation method The transmission power is transmitted to a plurality of transmission devices based on a demodulation step for demodulating a communication signal that is a signal transmitted by a transmission device that performs wireless communication among received signals, and the reception power measured in the demodulation step. And a control step for outputting a control signal including an instruction to be adjusted.

Then, control step, all of the signals received power from the communication signal and the communication signal is large processed, for each of the processing target, the received power of the processed signal, the reception Ri O signal to be processed comprises calculating a ratio of the total value of the received power of the power is low all the signals, at the control step, with each of the processed signal, the calculated ratio is below the predetermined value by calculating step In this case, a control signal including an instruction to increase the transmission power is transmitted to a transmission apparatus that transmits the signal to be processed, or a signal having a reception power smaller than the signal to be processed so that the ratio is equal to or greater than a predetermined value. A control signal including an instruction to reduce transmission power is output to the transmission apparatus .

A fourth invention is a wireless communication method in a wireless communication system comprising a plurality of transmission devices and a reception device that executes the reception method of the third invention, wherein each of the transmission devices has the same frequency as the other transmission devices And a transmission step for transmitting a signal in the same modulation system, a reception step on the transmission device side for receiving a control signal including an instruction for adjusting transmission power of the signal to be transmitted from the reception device, and an instruction included in the received control signal. and have groups Dzu, it executes a transmission control step of controlling transmission power of a signal transmitted in the transmitting step.

In the fourth invention, in the transmission control step, when receiving the control signals from the plurality of receiving devices, based on the number of received instructions for each content and the content of the instruction included in each of the received control signal adjusts the transmission power of a signal transmitted in the transmitting step.

  The present invention can improve throughput in a wireless environment in which an interference signal exists.

1 is a diagram illustrating an embodiment of a wireless communication system. It is a figure which shows an example of distribution of the received power of each signal which the receiver shown in FIG. 1 received. It is a figure which shows an example of the transmission / reception process in the radio | wireless communications system shown in FIG. FIG. 6 illustrates another embodiment of a wireless communication system. It is a figure which shows an example of the transmission / reception process in the radio | wireless communications system shown in FIG. It is a figure which shows an example of the radio | wireless communication using SIC. It is a figure which shows an example when the radio | wireless communication using SIC is difficult.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 shows an embodiment of a wireless communication system.

  The radio communication system SYS illustrated in FIG. 1 includes N transmission devices TX (TX1-TXN) and N reception devices RX (RX1-RXN). Each of the transmission devices TX1-TXN transmits a radio wave signal sig (sig1-sigN) modulated with the same frequency and the same modulation method. On the other hand, each receiving device RX receives the signal sig transmitted by each transmitting device TX. Note that wireless communication is performed between the transmission device TXk and the reception device RXk (k is an integer from 1 to N). That is, the receiving device RXk receives the signal sigk from the transmitting device TXk as a communication signal, and receives the signal sig from the other transmitting device TX as an interference signal. Further, the transmission device TX does not always transmit the signal sig.

  Note that the transmission device TX may have the function of the reception device RX, and the reception device RX may have the function of the transmission device TX.

  The transmission device TX1 includes a reception unit 10, a control unit 20, and a transmission unit 30. The transmission devices TX2-TXN have the same elements as the transmission device TX1.

  The receiving unit 10 receives a control signal (not shown) including an instruction to adjust the transmission power of the signal sig1 transmitted by the transmission device TX1 from the reception device RX via an antenna included in the transmission device TX1. The receiving unit 10 outputs the received control signal to the control unit 20.

  The control unit 20 is a processor or the like, and controls each element of the transmission device TX1 by executing a program stored in a storage device such as a memory included in the transmission device TX1. In addition, the control unit 20 causes the transmission unit 30 to transmit the signal sig1 with the transmission power adjusted based on the instruction included in the received control signal. Note that the transmission power adjustment amount may be preset in the transmission device TX1, or may be included in the received control signal.

  The transmission unit 30 transmits the signal sig1 with the transmission power instructed by the control unit 20 via the antenna included in the transmission device TX1.

  The reception device RX1 includes a reception unit 40, a demodulation unit 50, a control unit 60, and a transmission unit 70. Note that the receiving apparatuses RX2-RXN have the same elements as the receiving apparatus RX1.

  The reception unit 40 receives the signal sig transmitted from each transmission device TX via the antenna included in the reception device RX1. For example, the receiving unit 40 receives a signal sig1 from the transmission device TX1 indicated by a solid line as a communication signal, and receives a signal sig from another transmission device TX indicated by a dotted line as an interference signal.

  The demodulator 50 demodulates the signal sig1 as a communication signal by measuring the received power of the received signal received and sequentially demodulating the signal sig having the highest received power using the SIC.

  The control unit 60 is a processor or the like, and controls each element of the reception device RX1 by executing a program stored in a storage device such as a memory included in the reception device RX1. The control unit 60 has the function of the calculation unit 65. The calculation unit 65 may be implemented by a circuit together with the control unit 60, or may be operated by the control unit 60 executing a program.

  The calculation unit 65 uses the signal sig1 that is a communication signal and the signal sig whose received power is larger than the signal sig1 among the signals sig transmitted from each of the transmission devices TX. Then, for each signal to be processed, the calculation unit 65 calculates a ratio SIR between the reception power of the signal to be processed and the sum of the reception powers of all the signals sig that are smaller than the reception power of each signal to be processed. To do. For example, when the signal sigk from the transmission device TXk is a processing target, the calculation unit 65 is the sum of the reception power of the signal sigk and the reception power of all signals sig whose reception power is smaller than the reception power of the signal sigk. The ratio SIRk is calculated.

  The control unit 60 instructs each transmission device TX to adjust the transmission power of the signal sig so that the signal sig1 from the transmission device TX1 can be demodulated using all the ratio SIRs calculated by the calculation unit 65. A control signal including is generated. The operation of the control unit 60 and the calculation unit 65 and the ratio SIRk will be described with reference to FIGS.

  Note that the control unit 60 may generate a control signal for adjusting the transmission power of the signal sig for each transmission apparatus TX using the difference in power between the signals to be processed.

  The transmission unit 70 transmits a control signal addressed to each transmission device TX generated by the control unit 60 via an antenna included in the reception device RX1.

  FIG. 2 shows an example of the distribution of received power of each signal sig received by the receiving device RX1 shown in FIG. FIG. 2A shows a case where the signal sig1 has the maximum received power, and the received power decreases in the order of the signals sig2-sigN. FIG. 2B shows a case where the signal sig2 has the maximum received power and the signal sig1 has the received power between the signals sig2 and sig3.

  In the case of FIG. 2A, since the signal sig1 is a communication signal, the calculation unit 65 sums the received power of the signal sig1 and all received powers of the signals sig2-sigN whose received power is smaller than the signal sig1. A ratio SIR1 to the calculated value is calculated.

  The control unit 60 compares the ratio SIR1 calculated by the calculation unit 65 with a predetermined value β that is a condition for demodulating the signal sig1. When the ratio SIR1 is smaller than the predetermined value β, the control unit 60 generates a control signal including an UP instruction for increasing the transmission power of the signal sig1 to the transmission device TX1 so that the ratio SIR1 is equal to or greater than the predetermined value β. Further, the control unit 60 generates a control signal including a DOWN instruction for reducing the transmission power of the signal sig2 to the transmission device TX2.

  On the other hand, when the ratio SIR1 is equal to or larger than the predetermined value β and the ratio SIR1 is smaller than a value obtained by multiplying the predetermined value β and the margin δ, the control unit 60 has a signal sig1 sufficient to demodulate the signal sig1 from the transmission device TX1. Is determined to be different from the received power of the signal sig2. Note that the margin δ is a condition where the ratio SIR1 is smaller than the predetermined value β when the transmission power of the signal sig1 is lowered (that is, there is no room for reducing the difference between the reception power of the signal sig1 and the reception power of the signal sig2). It is a value larger than 1 indicating. In this case, for example, the control unit 60 generates a control signal including a Not DOWN instruction that does not cause the transmission device TX1 to reduce the transmission power of the signal sig1, and does not cause the transmission device TX2 to increase the transmission power of the signal sig2. A control signal including an UP instruction is generated. Note that the Not DOWN instruction is an instruction not to decrease at least the transmission power of the signal sig, and may increase the transmission power of the signal sig. Further, the Not UP instruction is an instruction not to increase at least the transmission power of the signal sig, and the transmission power of the signal sig may be decreased.

  And in the case of Fig.2 (a), the control part 60 does not produce | generate the control signal with respect to transmission apparatus TX3-TXN, and complete | finishes a process.

  Note that the control unit 60 includes the Not UP instruction or the Not DOWN instruction, and the ratio SIR1 exceeds the predetermined value β even if the difference between the received power of the signal sig1 and the received power of the signal sig2 is reduced. If it can be maintained, the control signal may not be transmitted to the transmission devices TX1 and TX2.

  In the case of FIG. 2B, since the signal sig1 is a communication signal, the calculation unit 65 adds up the reception power of the signal sig1 and all the reception powers of the signals sig3-sigN whose reception power is smaller than the signal sig1. A ratio SIR1 to the calculated value is calculated. In addition, the calculation unit 65 calculates a ratio SIR2 between the reception power of the signal sig2 and a value obtained by summing all the reception powers of the signals sig1 and sig3-sigN whose reception power is smaller than the signal sig2.

  Control unit 60 compares ratio SIR1 and ratio SIR2 calculated by calculation unit 65 with predetermined value β (or a value obtained by multiplying predetermined value β and margin δ). That is, the control unit 60 adjusts the transmission power for each of the transmission devices TX1 and TX2 based on the comparison between the ratio SIR2 and the predetermined value β (or the multiplication value of the predetermined value β and the margin δ) in the signal sig2 having the maximum reception power. A control signal including any of an UP instruction, a DOWN instruction, a Not UP instruction, or a Not DOWN instruction is generated. Next, the control unit 60 compares the ratio SIR1 with the predetermined value β (or a multiplication value of the predetermined value β and the margin δ), an UP instruction for adjusting the transmission power for each of the transmission devices TX1 and TX3, a DOWN instruction, A control signal including either a Not UP instruction or a Not DOWN instruction is generated.

  Note that since the instruction to the transmission device TX1 is determined using the ratio SIR2 and the ratio SIR1, the instruction determined using the ratio SIR2 may conflict with the instruction determined using the ratio SIR1. For example, combinations of conflicting instructions include an UP instruction and a DOWN instruction, an UP instruction and a Not UP instruction, and a DOWN instruction and a Not DOWN instruction. Therefore, when the instructions conflict, the control unit 60 generates a control signal including a Not Change instruction that causes the transmission apparatus TX1 to maintain transmission power.

  And in the case of FIG.2 (b), the control part 60 does not produce | generate the control signal with respect to transmission apparatus TX4-TXN, and complete | finishes a process.

  Further, when the signal sig1 has reception power between the signal sigk and the signal sig (k + 1), the calculation unit 65 sets the signal from the signal sig indicating the maximum reception power to the signal sig1 as signals to be processed, The ratio SIR of all signals is calculated sequentially. Then, the control unit 60 uses all the calculated ratios SIR and controls signals from the transmission device TX that transmits the signal sig indicating the maximum received power to the transmission device TX (k + 1) that transmits the signal sig (k + 1). Are generated sequentially.

  The control unit 60 may add the transmission power adjustment amount together with the UP instruction or the like to the generated control signal.

  FIG. 3 shows an example of transmission / reception processing in the wireless communication system SYS shown in FIG. The process illustrated in FIG. 3 illustrates a case where wireless communication is performed between the transmission device TX1 and the reception device RX1.

  When wireless communication is performed between each of the transmission device TX1 and the reception devices RX2-RXN, between each of the transmission devices TX2-TXN and the reception device RX1, and each of the transmission devices TX2-TXN and each of the reception devices RX2-RXN. This is the same as the processing shown in FIG.

  In step S100, for example, the control unit 20 determines whether or not an opportunity to transmit the signal sig1 has occurred due to acquisition of data to be transmitted. Alternatively, for example, when the control unit 20 receives a transmission instruction or the like from a user or an administrator of the transmission device TX1 via an input device such as a touch panel included in the transmission device TX1, an opportunity to transmit the signal sig1 It may be determined whether or not the occurrence has occurred. If the control unit 20 determines that an opportunity to transmit the signal sig1 has occurred, the process of the transmission device TX1 proceeds to step S130. On the other hand, when the control unit 20 determines that the opportunity to transmit the signal sig1 has not occurred, the processing of the transmission device TX1 proceeds to step S110.

  In step S110, the control unit 20 determines whether or not a control signal including an instruction to adjust the transmission power of the signal sig1 is received from the reception device RX via the reception unit 10. When it determines with the control part 20 having received the control signal, the process of transmitter TX1 moves to step S120. On the other hand, when it determines with the control part 20 not receiving the control signal, the process of the transmitter TX1 moves to step S100.

  In step S120, the control unit 20 holds the instruction included in the control signal received in step S110 in the storage device of the transmission device TX1. The process of the transmission device TX1 proceeds to step S100.

  In step S130, the control unit 20 adjusts the transmission power of the signal sig1 based on the instruction held in the storage device of the transmission device TX1 in step S120.

  In step S140, the transmission unit 30 transmits the signal sig1 with the adjusted transmission power.

  In step S150, the control unit 20 initializes the instruction held in step S120.

  In step S200, the control unit 60 determines whether or not the signal sig is received from the transmission device TX via the reception unit 40. When the control unit 60 determines that the signal sig is received, the processing of the receiving device RX1 proceeds to step S210. On the other hand, when the control unit 60 determines that the signal sig is not received, the process of the receiving device RX1 waits in step S200.

  In step S210, the control unit 60 determines whether or not a plurality of signals sig are superimposed on the reception signal received in step S200. When the control unit 60 determines that a plurality of signals sig are superimposed, the process of the reception device RX1 proceeds to step S230. On the other hand, when the control unit 60 determines that a plurality of signals sig are not superimposed (that is, for example, one signal sig1 is received), the process of the receiving device RX1 proceeds to step S220.

  In step S220, the demodulator 50 measures the received power of the signal sig1 of the communication signal received in step S200, demodulates the signal sig1, and acquires data. Then, the control unit 60 updates and holds the measured received power of the signal sig1 in the storage device of the receiving device RX1 in association with the transmitting device TX1. Then, the process of the receiving device RX1 proceeds to step S240.

  In step S230, the demodulator 50 measures the received power of the received signal including the plurality of signals sig received in step S200, and sequentially demodulates from the signal sig having a larger received power measured using the SIC. Then, the demodulator 50 acquires data included in the signal sig1 of the communication signal. Further, the control unit 60 updates and holds the received power of each demodulated signal sig among the plurality of signals sig in the storage device of the reception device RX1 in association with the transmission device TX of the transmission source. Then, the process of the receiving device RX1 proceeds to step S240.

  In step S240, the control unit 60 generates a control signal including an instruction to adjust the transmission power of the signal sig for each transmission device TX that is the transmission source of the signal sig received in step S200. In addition, the control part 60 does not produce | generate a control signal, when the signal received by step S200 is one.

  In step S250, the control unit 60 determines whether or not to transmit a control signal according to the presence or absence of the control signal generated in step S240 or the content of the instruction included in the generated control signal. When the control unit 60 determines to transmit a control signal, the process of the receiving device RX1 proceeds to step S260. On the other hand, when the control unit 60 determines not to transmit the control signal, the process of the receiving device RX1 proceeds to step S200.

In step S260, the control unit 60 transmits the control signal generated in step S240 to each transmission device TX via the transmission unit 70. Then, the transmission device TX1 acquires the data to be transmitted or performs the next transmission. When the instruction is received, the processing from step S100 to step S150 is repeatedly executed. In addition, the reception device RX1 repeatedly executes the processing from step S200 to step S260 in a predetermined period in which at least one signal sig is received.

  As described above, in the embodiment illustrated in FIG. 1 to FIG. 3, the control unit 60 of the reception device RX uses the calculated ratio SIR to transmit the communication signal and the signal sig whose reception power is larger than the communication signal. A control signal including an instruction to adjust the transmission power for each of the above is generated. As a result, the difference between the received power of the communication signal received by the receiving device RX and the received power of the signal sig, which is an interference signal adjacent to the communication signal, can be increased. The communication signal can be demodulated with high accuracy. That is, the radio communication system SYS can improve throughput in a radio environment where an interference signal exists.

  FIG. 4 shows another embodiment of a wireless communication system. The same or similar elements as those described in FIG. 1 are denoted by the same or similar reference numerals, and detailed description thereof will be omitted.

  The radio communication system SYSa illustrated in FIG. 4 includes N transmission devices TXa (TXa1-TXaN) and N reception devices RX. Each of the transmitters TXa1-TXaN transmits a radio wave signal sig modulated with the same frequency and the same modulation method. On the other hand, the receiving devices RX1-RXN receive the signal sig transmitted by each transmitting device TXa. Note that wireless communication is performed between the transmission device TXak and the reception device RXk. That is, the receiving device RXk receives the signal sig from the transmitting device TXak as a communication signal, and receives the signal sig from the other transmitting device TXa as an interference signal.

  The transmission device TXa1 includes a reception unit 10, a control unit 20a, and a transmission unit 30. Note that the transmission devices TXa2 to TXaN have the same elements as the transmission device TXa1.

  The control unit 20a is a processor or the like, and controls each element of the transmission device TXa1 by executing a program stored in a storage device such as a memory included in the transmission device TXa1. In addition, the control unit 20a causes the transmission unit 30 to transmit the signal sig1 with the transmission power adjusted based on the instruction included in the received control signal.

  When the control unit 20a receives a control signal from a plurality of receiving apparatuses RX during a period from when the signal sig1 is transmitted to when the next signal sig1 is transmitted, the UP instruction and the DOWN instruction received from each receiving apparatus RX. The transmission power of the signal sig1 is adjusted based on the number of Not UP instructions, Not DOWN instructions, or Not Change instructions. For example, the control unit 20a increases the transmission power when the number of UP instructions received during the period until the next signal sig1 is transmitted is larger than the sum of the numbers of DOWN instruction, Not UP instruction, and Not Change instruction. The next signal sig1 is transmitted to the transmitter 30.

  In addition, when the number of DOWN instructions received is larger than the sum of the number of UP instructions, Not DOWN instructions, and Not Change instructions, the control unit 20a reduces the transmission power and transmits the next signal sig1 to the transmission unit 30. Let Accordingly, the radio communication system SYSa can increase the number of reception devices RX that can demodulate communication signals according to the radio environment.

  FIG. 5 shows an example of transmission / reception processing in the radio communication system SYSa shown in FIG. Note that among the operations of the steps shown in FIG. 5, those showing the same or similar processing as the steps shown in FIG. 3 are given the same step numbers, and detailed descriptions thereof are omitted.

  The transmitting apparatus TXa1 executes the process of step S125 after executing the processes of step S100 and step S110. In step S100, when the control unit 20a determines that an opportunity to transmit the signal sig1 has occurred, the process of the transmission device TXa1 proceeds to step S135.

  In step S125, the control unit 20a holds the instruction included in the control signal received in step S110 in the storage device of the transmission device TX1. Further, the control unit 20a counts the number of received UP instructions, DOWN instructions, Not UP instructions, Not DOWN instructions, or Not Change instructions. Then, the process of the transmission device TXa1 proceeds to step S100.

  In step S135, the control unit 20a adjusts the transmission power of the signal sig1 based on the instruction having the largest number among the instructions held in the storage device of the transmission apparatus TXa1 in step S125.

  After performing the process of step S135, the transmission device TXa1 executes the process of step S140 and proceeds to the process of step S155.

  In step S155, the control unit 20 initializes the instruction and the number of instructions held in step S125.

  As described above, in the embodiment illustrated in FIG. 4 and FIG. 5, the control unit 60 of the reception device RX uses the calculated ratio SIR to transmit the communication device and the signal sig whose reception power is larger than the communication signal. A control signal including an instruction to adjust the transmission power for each of the above is generated. As a result, the difference between the received power of the communication signal received by the receiving device RX and the received power of the signal sig, which is an interference signal adjacent to the communication signal, can be increased. The communication signal can be demodulated with high accuracy. That is, the radio communication system SYSa can improve the throughput in a radio environment where an interference signal exists.

  Further, when the control unit 20a of the transmission device TXa receives control signals from the plurality of reception devices RX during a period until the next signal is transmitted, the UP instruction, the DOWN instruction, and the Not UP instruction received from each reception device RX. The transmission power of the signal sig is adjusted based on the number of the received Not DOWN instruction or Not Change instruction. As a result, the radio communication system SYSa can increase the number of reception devices RX that can demodulate communication signals according to the radio environment, and can further improve the throughput.

  From the above detailed description, features and advantages of the embodiments will become apparent. This is intended to cover the features and advantages of the embodiments described above without departing from the spirit and scope of the claims. Also, any improvement and modification should be readily conceivable by those having ordinary knowledge in the art. Therefore, there is no intention to limit the scope of the inventive embodiments to those described above, and appropriate modifications and equivalents included in the scope disclosed in the embodiments can be used.

1, 2, sig1-sigN ... signal; 10, 40 ... receiver; 20, 20a, 60 ... controller; 30, 70 ... transmitter; 50 ... demodulator; 65 ... calculator; Ra, Rb, RX1-RXN ... Receiving device; SYS, SYSa ... Wireless communication system; Ta, Tb, TX1-TXN, TXa1-TXaN ... Transmitting device

Claims (6)

A receiving unit that receives signals transmitted from each of a plurality of transmission devices at the same frequency and the same modulation scheme ;
A demodulator that measures received power of a received signal received by the receiver and demodulates a communication signal that is a signal transmitted by a transmitter that performs wireless communication among the received signals using a successive interference cancellation method;
A control unit that outputs a control signal including an instruction to adjust the transmission power to the plurality of transmission devices based on the reception power measured by the demodulation unit ; and
The controller is
The communication signal and all signals having higher reception power than the communication signal are to be processed, and for each of the processing target signals, the reception power of the processing target signal and the reception power is lower than the processing target signal. Including a calculation unit that calculates a ratio to the total value of the received power of all signals,
For each of the signals to be processed, when the ratio calculated by the calculation unit is less than a predetermined value, to the transmission device that transmits the signal to be processed so that the ratio is equal to or greater than the predetermined value control signal includes an instruction to increase the transmission power Te or received, wherein you output a control signal including an instruction to decrease the transmission power to the transmitter for receiving power from the signal to be processed to send a small signal, apparatus. In a wireless communication system comprising a plurality of transmission devices and the reception device according to claim 1,
Each of the transmitting devices
A transmitter that transmits a signal at the same frequency and the same modulation scheme as the other transmitters;
And the receiving unit of the transmitting apparatus side for receiving the control signal including an instruction to adjust the transmission power of a signal transmitted from the receiving device,
It said based on the instructions contained in the received control signal, a radio communication system, comprising a transmission control section that the transmission unit controls the transmission power of the signal to be transmitted. The wireless communication system according to claim 2 ,
The transmission control unit, when receiving the control signals from a plurality of the receiving device, based on the number of received prior Symbol instructions for each content and the content of the instructions included in each of the previous SL control signal received Te, adjusts the transmit power of the signal that the transmission unit transmits
A wireless communication system . A receiving step of receiving signals transmitted at the same frequency and the same modulation scheme from each of a plurality of transmitting devices;
A demodulation step of measuring a reception power of the reception signal received in the reception step, and demodulating a communication signal that is a signal transmitted by a transmission device that performs wireless communication among the reception signals using a successive interference cancellation method;
On the basis of the received power measured by the demodulating step, it has a control step of outputting a control signal including an instruction to adjust the transmit power to the plurality of transmission devices,
The control step includes
The communication signal and all signals having higher reception power than the communication signal are to be processed, and for each of the processing targets, the reception power of the signal to be processed and all reception powers lower than the signal to be processed A calculation step of calculating a ratio of the received power of the signal to a total value;
In the control step,
For each of the signals to be processed, when the ratio calculated in the calculation step is less than a predetermined value, the transmission apparatus transmits the signal to be processed so that the ratio is equal to or greater than the predetermined value. A control signal including an instruction to increase transmission power, or a control signal including an instruction to decrease transmission power to a transmission apparatus that transmits a signal having reception power smaller than the signal to be processed. . A wireless communication method in a wireless communication system comprising a plurality of transmission devices and a reception device that executes the reception method according to claim 4,
Each of the transmitting devices
A transmission step of transmitting a signal at the same frequency and the same modulation scheme as the other transmission devices;
A receiving step of the transmitting apparatus side for receiving the control signal including an instruction to adjust the transmission power of a signal transmitted from the receiving device,
And based on the said indication included in the received control signal, a radio communication method characterized by performing a transmission control step of controlling transmission power of the signal to be transmitted in the transmission step. The wireless communication method according to claim 5 , wherein
Wherein in the transmission control step, when receiving the control signals from a plurality of the receiving apparatus, the number of received prior Symbol instructions for each content and the content of the instructions included in each of the previous SL control signal received Based on this , the transmission power of the signal transmitted in the transmission step is adjusted .
A wireless communication method .

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