JP5925729B2 - Wireless communication apparatus and interference mitigation control method - Google Patents

Description

  The present invention relates to a radio communication apparatus and an interference mitigation control method for reducing co-channel interference and adjacent channel interference in a radio communication system.

  Rather than performing interference compensation on the interfering station apparatus side, the interfering station apparatus side reduces the amount of interference as transmission power control (TPC) that reduces interference between the same channels and nonlinear distortion compensation that reduces interference between adjacent channels. (DPD).

FIG. 9 shows a configuration example of DPD control (Patent Document 1).
In FIG. 9, the digital transmission signal output from the modulation unit (MOD) 11 is subjected to distortion compensation processing by the DPD unit 12 and then converted to an analog transmission signal by the D / A 13. The analog transmission signal is up-converted to a radio frequency by a frequency converter (UC) 14, amplified by a high-frequency amplifier (HPA) 15, and wirelessly transmitted from an antenna 16. Further, a part of the transmission signal is branched and output as a feedback signal from the high-frequency amplifier 15, down-converted to a baseband frequency by a frequency converter (DC) (not shown), and further converted to a digital transmission signal by A / D to be DPD Input to section 12.

  The DPD unit 12 compares the digital transmission signal input from the modulation unit 11 and the digital transmission signal fed back from the high frequency amplification unit 15 and subjected to A / D conversion, and adapts the distortion compensation coefficient so that the error is reduced. Therefore, the amplitude and phase of the digital transmission signal input from the modulation unit 11 are controlled and output so that the nonlinear distortion component of the analog transmission signal output from the high frequency amplification unit 15 is canceled out. Thereby, the out-of-band leakage power of the nonlinear distortion component included in the output (analog transmission signal) of the high-frequency amplifier 15 can be suppressed, and the interference with the adjacent channel can be reduced.

FIG. 10 shows a configuration example of TPC control.
In FIG. 10, a digital transmission signal output from the modulation unit (MOD) 11 is converted into an analog transmission signal by a D / A 13, up-converted to a radio frequency by a frequency conversion unit (UC) 14, and a high-frequency amplification unit (HPA) ) And is wirelessly transmitted from the antenna 16 to the opposite station device 30. The radio signal transmitted from the opposite station device 30 is received by the antenna 16, amplified by the low noise amplifying unit (LNA) 17, down-converted to the baseband frequency by the frequency converting unit (DC) 18, and the A / D 19 It is converted into a digital received signal and input to the demodulator (DEM) 20.

  The opposite station device 30 transmits TPC control information corresponding to the reception level. The TPC control information is, for example, “0” when the reception level is higher than the threshold, and “1” when the reception level is lower than the threshold. The demodulation unit 20 notifies the TPC unit 21 of the TPC control information as demodulation. The TPC unit 21 controls the transmission power output from the high frequency amplification unit 15 according to the TPC control information or an integral value thereof. In this way, the transmission power of the local station device is controlled so as to suppress the excess transmission power so that the reception level of the opposite station device 30 becomes a desired level, thereby reducing interference with the same channel of the third radio station. can do.

Japanese Patent No. 4641715

  In the configuration of the DPD control shown in FIG. 9, when the amplitude level of the analog transmission signal fed back from the high frequency amplification unit 15 is reduced, the number of bits is reduced when converted into a digital signal, and the digital feedback signal input to the DPD unit 12 is reduced. There is a problem in that the accuracy deteriorates and the distortion compensation accuracy deteriorates, and Patent Document 1 proposes a solution. That is, when the amplitude level of the analog transmission signal to be fed back is small, it is amplified using a variable gain amplifier to avoid deterioration of the accuracy of the digital feedback signal and distortion compensation accuracy.

  By the way, in the DPD control, the inverse characteristic of the nonlinear distortion of the output signal of the high frequency amplifying unit 15 is added to the input signal of the high frequency amplifying unit 15, the distortion characteristic is canceled at the output stage of the high frequency amplifying unit 15, and the distortion component is suppressed. It is a mechanism. On the other hand, TPC control is a mechanism for controlling transmission power in accordance with TPC control information based on the reception level of the opposite station device.

  When the DPD control and the TPC control are to be controlled at the same time, if the transmission power changes due to the TPC control, the distortion characteristic of the high-frequency amplifier 15 changes and does not match the reverse characteristic, and the DPD control does not function sufficiently. There is. This problem is a phenomenon that occurs when the DPD control and the TPC control are simultaneously controlled. Even if the distortion compensation accuracy is improved according to Patent Document 1, it cannot be avoided.

  An object of the present invention is to provide a radio communication apparatus and an interference mitigation control method capable of solving the problems in the case of performing DPD control and TPC control at the same time, and reducing interference between the same channel and interference between adjacent channels. .

  The first invention includes a DPD control unit that performs nonlinear distortion compensation (DPD) for reducing interference between adjacent channels, and a TPC control unit that performs transmission power control (TPC) for reducing interference between the same channels. In the wireless communication device provided, during communication with the opposite station device, the TPC control means is turned OFF, the DPD control means is turned ON to perform DPD control, and the TPC control information corresponding to the reception level of the opposite station device is monitored, When the control width of the transmission power of the local station device exceeds a predetermined step width, the DPC control means is turned off and the TPC control means is turned on to perform TPC control. After the transmission power is stabilized, the TPC control means is turned off. The DPD control means is turned on to return to DPD control, and an interference mitigation control unit that repeats DPD control and TPC control is provided.

  In the wireless communication device of the first invention, the interference mitigation control unit increases the step width when the frequency of switching from DPD control to TPC control exceeds a predetermined threshold, and when the frequency falls below the predetermined threshold A control configuration for reducing the step width is included.

  In the wireless communication apparatus of the first invention, the interference mitigation control unit has a control configuration for switching to TPC control according to TPC control information when the fluctuation range of the reception level at the opposite station exceeds a threshold during DPD control. Including.

  In the wireless communication apparatus of the first invention, the interference mitigation control unit shortens the switching period between the TPC control and the DPD control when the reception level fluctuation frequency in the opposite station exceeds the threshold during the DPD control, It includes a control configuration that lengthens the switching period between TPC control and DPD control when the fluctuation frequency falls below a threshold.

  In the second invention, DPD control means performs nonlinear distortion compensation (DPD) for reducing interference between adjacent channels, and TPC control means performs transmission power control (TPC) for reducing interference between the same channels. In the interference mitigation control method of the wireless communication apparatus to be performed, the interference mitigation control unit of the radio communication apparatus performs DPD control by turning off the TPC control means and turning on the DPD control means during communication with the opposite station apparatus. The step of monitoring TPC control information according to the reception level of the device, and the TPC control by turning off the DPD control means and turning on the TPC control means when the transmission power control width of the local station apparatus exceeds a predetermined step width And after the transmission power is stabilized by TPC control, the TPC control means is turned OFF, the DPD control means is turned ON, and the process returns to DPD control. And a flop repeats the DPD control and TPC control below.

  In the interference mitigation control method of the second invention, the interference mitigation control unit increases the step width when the frequency of switching from DPD control to TPC control exceeds a predetermined threshold, and when the frequency falls below the predetermined threshold Control to reduce the step width.

  In the interference mitigation control method of the second invention, the interference mitigation control unit performs control to switch to TPC control according to TPC control information when the fluctuation range of the reception level at the opposite station exceeds the threshold during DPD control. Do.

  In the interference mitigation control method of the second invention, the interference mitigation control unit shortens the switching period between the TPC control and the DPD control when the fluctuation frequency of the reception level in the opposite station exceeds the threshold during the DPD control, When the fluctuation frequency falls below a threshold value, control is performed to lengthen the switching cycle between TPC control and DPD control.

  According to the present invention, interference between the same channel and interference between adjacent channels can be reduced at the same time, so that the interference condition of the entire radio system can be reduced. In particular, wireless communication devices using the same frequency channel can be brought closer by reducing the interference between the same channels, and the channel spacing on the frequency axis can be narrowed by reducing the interference between adjacent channels, thereby improving the frequency utilization efficiency. It can be realized at the same time.

It is a figure which shows the structural example of the radio | wireless communication apparatus of this invention. It is a flowchart which shows Example 1 of the control procedure in the radio | wireless communication apparatus of this invention. It is a flowchart which shows the control procedure at the time of starting in the radio | wireless communication apparatus of this invention. It is a flowchart which shows Example 2 of the control procedure in the radio | wireless communication apparatus of this invention. It is a figure explaining Example 3 of this invention. It is a figure explaining Example 4 of this invention. It is a figure explaining Example 5 of this invention. It is a figure which shows the control form by this invention. It is a figure which shows the structural example of DPD control. It is a figure which shows the structural example of TPC control.

FIG. 1 shows a configuration of an embodiment of a wireless communication apparatus of the present invention.
In FIG. 1, a modulation unit (MOD) 11, a DPD unit 12, a D / A 13, a frequency conversion unit (UC) 14, a high frequency amplification unit (HPA) 15, an antenna 16, a low noise amplification unit (LNA) 17, and a frequency conversion unit. (DC) 18, A / D 19, demodulator (DEM) 20, and TPC unit 21 have the same configurations as the DPD-controlled radio communication device shown in FIG. 9 and the TPC-controlled radio communication device shown in FIG. 10.

  The feature of the present embodiment is that the TPC control information output from the demodulator 20 is not directly input to the TPC unit 21 but is input to the interference mitigation controller 22, and the interference mitigation controller 22 uses the TPC unit 21 and the DPD unit 12 as follows. It is in the place where it controls by the procedure demonstrated in (1). Along with this, the configurations of the TPC unit 21 and the DPD unit 12 are slightly different from the conventional ones, but there is no difference in the main functions as long as the function to turn on / off is added.

Example 1
FIG. 2 shows a first embodiment of the control procedure in the wireless communication apparatus of the present invention.
In FIG. 2, when the wireless communication apparatus is communicating, the interference mitigation control unit 22 turns off TPC control (S1), turns on DPD control (S2), and monitors TPC control information (S3). That is, TPC control information notified from the opposite station is monitored while performing control for reducing interference between adjacent channels by the DPD unit 12.

  Here, when the state in which the reception level in the opposite station apparatus is larger than the threshold value continues and the control width of the transmission power controlled according to the TPC control information exceeds the step width (S3: Yes), the interference mitigation control unit 22 turns off the DPD control (S4), turns on the TPC control (S5), and the TPC unit 21 starts controlling the transmission power for the high frequency amplification unit 15 (S6). When the reception level at the opposite station apparatus is stabilized within the threshold value according to the TPC control information (S6: Yes), the interference mitigation control unit 22 turns off the TPC control again (S1) and turns on the DPD control (S1). S2), the process returns to the process of monitoring the TPC control information (S3).

FIG. 3 shows a control procedure at startup in the wireless communication apparatus of the present invention.
In FIG. 3, the wireless communication apparatus turns off TPC control at the maximum transmission power at startup (S11), turns on DPD control (S12), stabilizes DPD control (S13), and turns off DPD control (S14). ), TPC control is turned on (S15). Then, after the transmission power is stabilized (S16), the TPC control is turned off and the DPD control is turned on, and the process proceeds to the communication control shown in FIG. 2 (S17 = S1, S2).

(Example 2)
FIG. 4 shows a second embodiment of the control procedure in the wireless communication apparatus of the present invention.
In FIG. 4, the processes from step S1 to S6 are the same as those in the first embodiment, and the TPC control information is monitored while performing DPD control (S1 to S3). When the TPC control is necessary, the TPC control is performed. (S4 to S6), and return to DPD control when TPC control is stabilized.

  Here, it is determined whether or not the frequency of performing TPC control within a certain time (the frequency of Yes in S3) exceeds a threshold value (S7). If the frequency of performing TPC control exceeds the threshold value, TPC control is performed. The step width of the transmission power controlled according to the information is expanded (S8), and the step width is reduced if the frequency of performing the TPC control is equal to or less than the threshold (S9). Thereby, switching between DPD control and TPC control can be performed adaptively, and interference between the same channel and interference between adjacent channels can be efficiently reduced.

(Example 3)
Embodiment 3 will be described with reference to FIG.
When the opposite station device (base station) and the own station device (wireless terminal) communicate by the FDD method, as shown in Fig. 5 (1), the own station device transmits the packet and the opposite station device sets the reception level. Measure and return the TPC control information to the local station device. The own station apparatus performs TPC control according to the TPC control information. Therefore, in the TPC control by the FDD method, a transmission delay time for one round trip between the own station apparatus and the opposite station apparatus is required.

  On the other hand, when the opposite station apparatus (base station) and the own station apparatus (wireless terminal) communicate by the TDD method, the opposite station apparatus transmits packets at a predetermined timing as shown in FIG. The station apparatus can measure the reception level, generate TPC control information by itself, and perform TPC control. As a result, in the TDD system, even when there is no transmission data from the local station apparatus, TPC control can be performed by the received signal of the local station apparatus, and the convergence of the TPC control in step S6 shown in FIGS. 2 and 3 is accelerated. Further, since the TPC control can be performed by signal transmission in only one direction and the time is shortened, it is possible to follow the propagation fluctuation at a high speed, and as a result, the accuracy of the switching timing between the TPC control and the DPD control can be improved.

Example 4
Embodiment 4 will be described with reference to FIG.
Step S3 shown in FIG. 2 and FIG. 3 is a control for switching from DPD control to TPC control when the control width of the transmission power with respect to the reception level in the opposite station apparatus exceeds the step width while TPC control is stopped during DPD control. Met.

  In the fourth embodiment, when the propagation variation is large, the reception level of the opposite station device varies greatly as shown in FIG. When the fluctuation range exceeds the threshold value, control is performed to switch from DPD control to TPC control based on TPC control information notified from the opposite station device.

(Example 5)
Embodiment 5 will be described with reference to FIG.
In steps S7 to S9 shown in the second embodiment, the step width of the transmission power controlled according to the TPC control information is adjusted according to the frequency of performing the TPC control.

  The fifth embodiment corresponds to a case where the period of propagation fluctuation changes. As shown in FIG. 7, when the frequency at which the reception level crosses the threshold is counted in the opposite station device within a certain time and the frequency is high, the switching period between TPC control and DPD control is shortened, and the frequency is low In addition, the switching cycle of TPC control and DPD control is lengthened.

(Control form)
FIG. 8 shows a control mode according to the present invention.
In FIG. 8, in a radio communication system (P-MP radio communication system) having a plurality of terminal station apparatuses 42 that communicate with a base station apparatus 41, the present invention relates to each of the terminal station apparatuses 42-1 and 42-2 as a base station apparatus. 41, the TPC control information is obtained from the TPC control for reducing the interference between the same channels for the adjacent base station area, and the DPC control for reducing the interference between the adjacent channels is simultaneously performed for the same base station area. It can be carried out.

  In addition, when the base station apparatus 41 receives signals from a plurality of terminal station apparatuses 42-1 and 42-2, the reception level of the base station apparatus 41 is received by TPC control of each of the terminal station apparatuses 42-1 and 42-2. It can be suppressed within the dynamic range, and at the same time, out-of-band leakage power can be suppressed.

11 Modulator (MOD)
12 DPD section 13 D / A
14 Frequency converter (UC)
15 High frequency amplifier (HPA)
16 Antenna 17 Low noise amplifier (LNA)
18 Frequency converter (DC)
19 A / D
20 Demodulator (DEM)
21 TPC unit 22 Interference mitigation control unit 30 Opposite station device

Claims (8)

DPD control means for performing nonlinear distortion compensation (DPD) to reduce interference between adjacent channels;
In a wireless communication apparatus comprising: TPC control means for performing transmission power control (TPC) for reducing interference between the same channels,
During communication with the opposite station device, the TPC control means is turned OFF, the DPD control means is turned ON to perform DPD control, TPC control information corresponding to the reception level of the opposite station device is monitored, and the local station device transmits When the power control width exceeds a predetermined step width, the DPD control means is turned OFF, the TPC control means is turned ON to perform TPC control, and after the transmission power is stabilized, the TPC control means is turned OFF, A wireless communication apparatus comprising: an interference mitigation control unit that turns on the DPD control means to return to the DPD control and repeats the DPD control and the TPC control. The wireless communication device according to claim 1,
The interference mitigation control unit expands the step width when the frequency of switching from the DPD control to the TPC control exceeds a predetermined threshold, and reduces the step width when the frequency falls below a predetermined threshold. A wireless communication device comprising a control configuration. The wireless communication device according to claim 1,
The interference mitigation control unit includes a control configuration that switches to the TPC control according to the TPC control information when a fluctuation range of a reception level in the opposite station exceeds a threshold during the DPD control. Wireless communication device. The wireless communication device according to claim 1,
The interference mitigation control unit shortens the switching period between the TPC control and the DPD control when the fluctuation frequency of the reception level in the opposite station exceeds a threshold during the DPD control, and the fluctuation frequency becomes less than the threshold. A wireless communication apparatus comprising: a control configuration that lengthens a switching period between the TPC control and the DPD control when the time is lower than the lower limit. Non-linear distortion compensation (DPD) for reducing interference between adjacent channels by DPD control means, and interference of a radio communication apparatus that performs transmission power control (TPC) for reducing interference between same channels by TPC control means In the mitigation control method,
The interference reduction control unit of the wireless communication device,
During communication with the opposite station device, turning off the TPC control means, turning on the DPD control means to perform DPD control, and monitoring TPC control information according to the reception level of the opposite station device;
When the control width of the transmission power of the local station apparatus exceeds a predetermined step width, the DPD control means is turned off, the TPC control means is turned on and TPC control is performed;
After the transmission power is stabilized by the TPC control, the step of turning off the TPC control means, turning on the DPD control means and returning to the DPD control, and thereafter repeating the DPD control and the TPC control. Interference mitigation control method. The interference mitigation control method according to claim 5,
The interference mitigation control unit expands the step width when the frequency of switching from the DPD control to the TPC control exceeds a predetermined threshold, and reduces the step width when the frequency falls below a predetermined threshold. An interference mitigation control method characterized by performing control. The interference mitigation control method according to claim 6,
The interference mitigation control unit performs control to switch to the TPC control according to the TPC control information when a fluctuation range of a reception level in the opposite station exceeds a threshold during the DPD control. Interference mitigation control method. The interference mitigation control method according to claim 6,
The interference mitigation control unit shortens the switching period between the TPC control and the DPD control when the fluctuation frequency of the reception level in the opposite station exceeds a threshold during the DPD control, and the fluctuation frequency becomes less than the threshold. An interference mitigation control method characterized by performing control to increase a switching period between the TPC control and the DPD control when the time is lower.

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