JP2005184708A - Radio communication system, radio base station, mobile station, and transmit power control method used for them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system capable of realizing a more stabilized handover and improving the quality. <P>SOLUTION: When radio base stations 1-1 and 1-2 and a mobile station 2 perform synthesis between sectors, they perform TPC (Transmit Power Control) bit control and transmit power control for each of radio links RL1 to RL3. When the radio base stations 1-1 and 1-2 and the mobile station 2 cannot perform TPC bit control and transmit power control, they perform preferential weighting to a radio link of good quality, and synthesize and take out a TPC bit, when the synthesis between sectors is conducted and the TPC bit is taken out. Under a situation that a BER (Bit Error Ratio) is worsened, the radio base stations 1-1 and 1-2 and the mobile station 2 perform transmit power control if the TPC bit takes a same value continuously. Under a situation that the quality becomes worse than a certain constant value, the radio base stations 1-1 and 1-2 and the mobile station 2 activate a Power Balancing function, using an average value of the present transmission power as a reference value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a radio communication system, a radio base station, a mobile device, and a transmission power control method used therefor, and more particularly, to a transmission power control and data combination method during inter-sector handover in a W-CDMA (Wideband Code Division Multiple Access) scheme. .

  Conventionally, in this type of transmission power control method, when there are a plurality of radio links and the plurality of radio links are combined between sectors, a method of performing the same transmission power control with the combined links has been taken. Yes.

  As a transmission power control method similar to the above, a method of acquiring TPC bits based on TPC (Transmit Power Control) bit redundancy, soft decision, and hard decision (see, for example, Patent Document 1), A method of performing transmission power control in consideration of SIR (Signal to Interference power Ratio) in synthesis (for example, see Patent Document 2), a method of performing transmission power control during soft handover based on SIR (for example, see Patent Document 3) ), A propagation path is estimated by a common pilot and an individual pilot, and a correction calculation is performed from the estimated value to perform RAKE combining (for example, see Patent Document 4).

  As another transmission power control method, a method of performing transmission power control based on a pilot symbol pattern (see, for example, Patent Document 5), a target SIR value is measured based on an error rate by measuring an error rate of a received signal. A method of changing the SIR (see, for example, Patent Document 6), a method of stopping TPC or implementing TPC based on the quality (for example, see Patent Document 7), and making the SIR of each sector comparable There is a method of improving (for example, see Patent Document 8).

JP 2003-110460 A JP 2002-330102 A Japanese Patent Laid-Open No. 08-018503 JP 2002-111570 A JP 2000-115072 A Republished patent WO97 / 50197 Japanese Patent Laid-Open No. 2003-169018 JP 2000-165319 A

  In the conventional transmission power control method described above, in a situation where a radio link in a good quality state in a handover state and a radio link in a poor quality state coexist, a wrong TPC bit is dragged by a poor quality radio link. There is a problem in that, by combining and performing erroneous transmission power control, the radio link that was stable before the handover is lost in synchronization.

  Therefore, an object of the present invention is to solve the above-described problems, realize a more stable handover, and improve the quality, a radio communication system, a radio base station, a mobile device, and transmission power used for them It is to provide a control method.

  The radio communication system according to the present invention has a plurality of radio links between a plurality of radio base stations and a mobile station, and the same transmission power control is performed on the synthesized links when the plurality of radio links are synthesized between sectors. A communication system that performs BER (Bit Error Ratio) measurement of DPCH (Dedicated Physical Channel) and acquisition of TPC (Transmit Power Control) bits for each of the plurality of radio links in the inter-sector combination And the means for performing the transmission power control and the TPC bit control based on the result of the BER measurement and the acquisition of the TPC bit are provided in each of the plurality of radio base stations and the mobile device.

  The radio base station according to the present invention is a radio base station that performs the same transmission power control with a combined link when a plurality of wireless links exist with a mobile device and the plurality of wireless links are combined between sectors. Means for performing BER (Bit Error Ratio) measurement of DPCH (Dedicated Physical Channel) and acquisition of TPC (Transmit Power Control) bit for each of the plurality of radio links in the inter-sector combination, Means for performing the transmission power control and the TPC bit control based on the result of acquisition of the TPC bit.

  The mobile device according to the present invention has a plurality of wireless links between a plurality of wireless base stations, and the same transmission power control is performed on the combined links when combining the plurality of wireless links between sectors. A BER (Bit Error Ratio) measurement of DPCH (Dedicated Physical Channel) and acquisition of a TPC (Transmit Power Control) bit for each of the plurality of radio links in the inter-sector combination, and the BER Means for performing the transmission power control and the TPC bit control based on the result of the measurement and the acquisition of the TPC bit.

  A transmission power control method according to the present invention is a link synthesized when a plurality of radio links are combined between sectors in a radio communication system in which a plurality of radio links exist between a plurality of radio base stations and a mobile device. A transmission power control method for performing the same transmission power control, wherein a BER (Bit Error Ratio) measurement of DPCH (Dedicated Physical Channel) is performed by combining between sectors on each of the plurality of radio base stations and the mobile device. And TPC (Transmit Power Control) bit acquisition for each of the plurality of radio links, and the transmission power control and the TPC bit control based on the results of the BER measurement and the TPC bit acquisition And steps.

  That is, in order to solve the above problems, the wireless communication system of the present invention performs TPC (Transmit Power Control) bit control and transmission power control for each wireless link when performing inter-sector combining. In this case, the mobile device needs to be able to control transmission power for each radio link, as described above.

  In addition, in the wireless communication system of the present invention, when the above TPC bit control and transmission power control cannot be performed, preferential weighting is performed on a high-quality wireless link when extracting TPC bits by combining between sectors. , TPC bits are synthesized and extracted.

  Further, in the wireless communication system of the present invention, in a situation where the BER (Bit Error Rate) is deteriorated, the transmission power is controlled when the TPC bits continuously show the same value, and the number of consecutive times according to the measured value of the BER. Is controlled proportionally.

  Furthermore, in the wireless communication system of the present invention, when the quality becomes lower than a certain value, the power balancing function is operated using the current average value of transmission power as a reference value. This is an Adjustment Loop function defined by 3GPP (3rd Generation Partnership Project).

  As a result, in the wireless communication system of the present invention, stable handover is performed by improving transmission power control during handover between a wireless base station and a mobile station in a W-CDMA (Wideband Code Division Multiple Access) system. It becomes possible to perform communication with higher quality.

  With the configuration and operation as described below, the present invention can achieve more stable handover and can improve the quality.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a radio communication system according to an embodiment of the present invention, and FIG. 2 is a diagram showing formation of a radio link in the radio communication system according to an embodiment of the present invention.

  In the radio communication system according to an embodiment of the present invention, as shown in FIG. 1, in a region A where a plurality of sectors 101, 102, 103 managed by a plurality of radio base stations 1-1, 1-2 are overlapped. It is assumed that transmission power control and data combination are performed while the mobile device is moving in the direction of the arrow (when the mobile device performs handover).

  In this case, in this embodiment, as shown in FIG. 2, communication is performed between the radio base stations 1-1 and 1-2 and the mobile device 2 through the three radio links RL1, RL2 and RL3, and the radio Signal synthesis is performed at each node of the base stations 1-1 and 1-2 and the mobile device 2.

  3 is a block diagram showing the configuration of the receiving units of the radio base stations 1-1 and 1-2 and the mobile device 2 in FIG. 2, and FIG. 4 is a block diagram of the radio base stations 1-1 and 1-2 in FIG. It is a block diagram which shows the structure of the transmission part of each mobile device.

  In FIG. 3, the receiving units of the radio base stations 1-1, 1-2 and the mobile device 2 are antennas 11-13, demodulators 14-16, BER (Bit Error Rate) measurement, TPC (Transmit Power Control). The acquisition units 17 to 19, the reconstruction / combination unit 20, and the BER comparison / TCP calculation unit 21 are configured.

  In FIG. 4, the transmission units of the radio base stations 1-1 and 1-2 and the mobile device 2 are antennas 11 to 13 (also used as the reception unit described above), modulation units 22 to 24, and signal generation unit 25. And a power control unit 26.

  The reception processing by the reception unit and the transmission processing by the transmission unit of each of the radio base stations 1-1 and 1-2 and the mobile device 2 will be described with reference to FIGS. In addition, the number of antennas etc. change with each structure, or a present Example demonstrates the example of the three antennas 11-13.

  In this embodiment, when signals are received, the signals received by the antennas 11 to 13 are demodulated by the demodulation units 14 to 16, respectively, and the BER measurement / TPC acquisition units 17 to 19 individually measure the BER and acquire the TPC. .

  As for the acquisition of TPC, when transmission power control is performed for each radio link RL1, RL2, RL3, the BER measurement / TPC acquisition units 17 to 19 acquire each of the radio links RL1, RL2, RL2, and RL3. When the same TPC is specified in RL3, the received signal is obtained after being synthesized by the reconstruction / synthesis unit 20 (illustrated by a dotted arrow in FIG. 3).

  The BER comparison / TCP calculation unit 21 weights the BER measured for each radio link RL1, RL2, RL3 by the BER measurement / TPC acquisition units 17 to 19, and the reconfiguration / combination unit 20 receives the received signal based on the result. Is synthesized.

  Next, in the present embodiment, at the time of signal transmission, each of the radio links RL1, RL2, RL3 according to the TPC input obtained by the power control unit 26 based on the TPC acquired by the BER comparison / TCP calculation unit 21 described above. The transmission power is controlled.

  Further, the signal generation unit 25 generates a signal for each of the radio links RL1, RL2, and RL3 based on the transmission data input. The signals generated by the signal generation unit 25 are modulated by the modulation units 22 to 24 and transmitted from the antennas 11 to 13.

  When the transmission power is controlled for each of the radio links RL1, RL2, and RL3, each TPC is assigned to each of the radio links RL1, RL2, and RL3 based on the reception level of each of the radio links RL1, RL2, and RL3. Append.

  FIG. 5 is a diagram showing the configuration of an uplink radio frame used in one embodiment of the present invention, and FIG. 6 is a diagram showing the configuration of a downlink radio frame used in one embodiment of the present invention. 5 and 6 show a DPCH (Dedicated Physical Channel) radio frame based on the current W-CDMA.

  The DPCH is composed of a DPCCH (Dedicated Physical Control Channel) for control and a DPDCH (Dedicated Physical Data Channel) for data. Here, the pilot bit and transport format combination indicator (TFCI) bit of the DPCCH are fixedly determined.

In this embodiment, an additional fixed bit is provided in the DPCCH, and a BER is calculated and acquired for a fixedly determined bit in another DPCCH.

  Transmission power control and data synthesis in a wireless communication system according to an embodiment of the present invention will be described with reference to FIGS. In this embodiment, transmission power control is performed when handing over to a plurality of sectors 101, 102, and 103 performed between the radio base stations 1-1 and 1-2 and the mobile device 2 in W-CDMA. In the present embodiment, transmission power control suitable for the performance and operation of the radio base stations 1-1 and 1-2 and the mobile device 2 is performed.

  When the mobile device 2 moves between the wireless base stations 1-1 and 1-2 and performs wireless transmission / reception over a plurality of sectors 101, 102, 103, the mobile device 2 moves to each sector 101. , 102 and 103, radio links RL1, RL2 and RL3 are established between the radio base stations 1-1 and 1-2. The radio base stations 1-1, 1-2 and the mobile device 2 combine and extract data from the plurality of radio links RL1, RL2, RL3, and control the transmission power of each radio link RL1, RL2, RL3.

  FIG. 7 is a flowchart showing transmission power control processing of the wireless communication system according to the embodiment of the present invention. The transmission power control process of the wireless communication system according to the embodiment of the present invention will be described with reference to FIGS.

  In order to solve the above problems, a radio communication system according to an embodiment of the present invention (1) performs TPC bit control and transmission power control for each radio link RL1, RL2, RL3 when performing inter-sector combining. And go. In this case, the mobile device 2 also needs to be able to control transmission power for each of the radio links RL1, RL2, and RL3, as described above.

  In the wireless communication system according to the embodiment of the present invention, (2) when the above TPC bit control and transmission power control cannot be performed, a high-quality wireless link is obtained when combining the sectors and extracting the TPC bit. Are preferentially weighted, and the TPC bits are synthesized and extracted.

  Furthermore, in the wireless communication system according to the embodiment of the present invention, (3) In a situation where the BER is deteriorated, the transmission power is controlled when the TPC bits continuously show the same value, and the BER is continuously measured. It is assumed that the number of times of control is controlled in proportion.

  Furthermore, in the radio communication system according to the embodiment of the present invention, (4) when the quality becomes lower than a certain value, the power balancing function is operated with the average value of the current transmission power as a reference value. This is an Adjustment Loop function defined by 3GPP (3rd Generation Partnership Project). Hereinafter, the four items (1) to (4) will be described.

  In the improvement of (1), TPC bits are acquired and transmitted for each radio link RL1, RL2, RL3 even when inter-sector combining is performed (step S2 in FIG. 7) during handover (step S1 in FIG. 7). And transmission power control are performed (step S3 in FIG. 7). Regarding the control of the TPC bit to be transmitted, it is assumed that the mobile station 2 can also control for each of the radio links RL1, RL2, and RL3.

  There is a high possibility that a TPC bit is erroneous in a radio link having a poor quality and a low BER, and it is necessary to prevent transmission power control from being performed by a wrong TPC bit.

  In this embodiment, when inter-sector combining is performed, if a TPC bit is extracted after combining a high-quality radio link and a low-quality radio link, a bit error occurs. It should be avoided that transmission power control is performed by bits.

  In this embodiment, in the improvement of (2), when performing the above-mentioned inter-sector combination, transmission power control by TPC bits and control of TPC bits to be transmitted cannot be performed for each radio link RL1, RL2, RL3. In the case (step S4 in FIG. 7), when the TPC bits are extracted by combining between sectors, a high-quality wireless link is preferentially weighted (steps S6 and S7 in FIG. 7), and the TPC bits are combined and extracted to transmit power. (Step S8 in FIG. 7).

  That is, in the present embodiment, the BER is measured in each of the radio links RL1, RL2, and RL3, and the weighting is performed by giving priority to the radio links having a small BER. This is not only the synthesis of the TPC bits, but also normal communication data (including voice data and the like) can be synthesized with high quality data with few errors.

In this embodiment, the weight (Y) and BER (X) are set in inverse proportion. That is, the weight (Y) and BER (X) are
Y = a / X + b (1)
It becomes the relationship of the expression. Here, the coefficients a and b are weighting gradients and correction values, and the values are adjusted according to the environment.

  Further, in this embodiment, when performing BER measurement, it is necessary to use a value adapted to the radio situation, so it is necessary to perform measurement in as short a time as possible for each radio frame or each slot. When the BER is measured for each slot, several additional fixed bits are provided separately from the pilot part, and the bit error of the fixedly determined part is calculated and determined as an approximate BER.

  Subsequently, in the present embodiment, in the improvement of (3), when the BER is somewhat worse (step S6 in FIG. 7) and the TPC bits continuously show the same value (step S9 in FIG. 7), Transmission power is controlled (step S10 in FIG. 7). In this case, the number of consecutive times is controlled in proportion to the measured value of BER.

  In a situation where the BER is bad, there is a possibility that the TPC bit is erroneous. Therefore, transmission power control is performed when the same value is detected continuously. When it is necessary to increase the transmission power, the TPC bit requests that the mobile device 3 continuously increase the transmission power. As a result, in this embodiment, it is possible to perform more stable communication than erroneously performing transmission power control in accordance with an incorrect TPC bit instruction.

  The above control is desirably performed for each of the radio links RL1, RL2, and RL3. Even when the above control cannot be performed for each of the radio links RL1, RL2, and RL3, more stable communication can be performed by the above control.

  However, in the above control, if continuous TPC bits are monitored with too much redundancy, the transmission power control does not operate at all, so the next improvement is controlled.

  In the present embodiment, in the improvement of (4), when the quality becomes worse than a certain value (step S11 in FIG. 7), the average value of the current transmission power for the last 100 ms is referred to as the reference value (DL Reference Power). As shown in FIG. 7, the power balancing function is operated (step S12 in FIG. 7).

  In this embodiment, when inter-sector combining is performed in a handover state, the radio base stations 1-1, 1-2 and the mobile device 2 both control TPC and transmit power for each radio link RL1, RL2, RL3. When BER measurement is possible, by performing each control for each of the radio links RL1, RL2, and RL3, it is possible to reduce quality degradation and control error due to combining with other links.

  Also, in this embodiment, when inter-sector combining is performed in a handover state, TPC control / transmission is performed for each of the radio links RL1, RL2, and RL3 in the radio base stations 1-1 and 1-2 and the mobile device 2. If the power cannot be controlled, BER is measured for each radio link RL1, RL2, RL3, weighted according to the BER measurement value, inter-sector synthesis is performed to obtain the TPC bit, and the obtained TPC is obtained. Control transmission power based on bits.

  Further, in this embodiment, when the result of BER measurement deteriorates to a certain value (α) or more, transmission power control is performed by detecting a continuous value of TPC bits in proportion to BER.

  Furthermore, in this embodiment, when the result of the BER measurement deteriorates to a certain value (β) or more, the current transmission power is measured and the Power Balancing function is executed. Regarding the measured value of BER, α <β. In the present embodiment, the above processing (steps S1 to S12 in FIG. 7) is repeated until the processing ends (step S13 in FIG. 7).

  As described above, in this embodiment, with the configuration and operation as described above, a stable handover at the time of handover between the radio base stations 1-1 and 1-2 and the mobile device 2 in the W-CDMA system. Communication with higher quality.

  In the present embodiment, transmission power control is performed for each of the radio links RL1, RL2, and RL3 at the time of handover between the radio base stations 1-1 and 1-2 and the mobile device 2 in the W-CDMA system. Therefore, it is possible to prevent excessive power transmission by being attracted by other radio links, and to suppress interference.

It is a block diagram which shows the structure of the radio | wireless communications system by one Example of this invention. FIG. 3 is a diagram illustrating formation of a radio link in a radio communication system according to an embodiment of the present invention. It is a block diagram which shows the structure of the receiving part of each of the wireless base station of FIG. 2, and a mobile device. It is a block diagram which shows the structure of the transmission part of each of the radio base station of FIG. 2, and a mobile device. It is a figure which shows the structure of the uplink radio frame used by one Example of this invention. It is a figure which shows the structure of the downlink radio | wireless frame used in one Example of this invention. It is a flowchart which shows the process of the transmission power control of the radio | wireless communications system by one Example of this invention.

Explanation of symbols

1-1, 1-2 Radio base station
2 Mobile equipment
11-13 Antenna
14-16 demodulator
17-19 BER measurement / TPC acquisition unit
20 Reconfiguration / synthesis unit
21 BER Comparison / TCP Operation Unit
22-24 Modulator
25 Signal generator
26 Power control unit 101, 102, 103 sectors
A area RL1, RL2, RL3 radio link

Claims (20)

  A wireless communication system in which a plurality of wireless links exist between a plurality of wireless base stations and a mobile device, and when the plurality of wireless links are combined between sectors, the same transmission power control is performed on the combined links. , Means for performing BER (Bit Error Ratio) measurement of DPCH (Dedicated Physical Channel) and acquisition of TPC (Transmit Power Control) bit for each of the plurality of radio links in the inter-sector combination, BER measurement, and TPC A wireless communication system, characterized in that each of the plurality of wireless base stations and the mobile device has means for performing the transmission power control and the TPC bit control based on a result of bit acquisition.   Means for measuring the reception level and the BER of each sector when the TPC bit cannot be obtained and the transmission power control cannot be performed; means for weighting the radio link according to the measurement result of the BER; 2. The wireless base station and the mobile device each include means for performing inter-sector combining and performing transmission power control by extracting the TPC bit in a wireless link that has been performed. Wireless communication system.   3. The plurality of radio base stations and each of the mobile devices each include means for performing the transmission power control when the BER deteriorates and the TPC bits continuously show the same value. Wireless communication system.   An additional fixed bit set in advance in the DPCH is provided separately from a pilot part, and the BER is calculated and obtained for another fixedly determined bit by the additional fixed bit. The radio | wireless communications system in any one of Claims 1-3.   4. The wireless communication system according to claim 1, wherein the wireless communication system is a W-CDMA (Wideband Code Division Multiple Access) system.   A radio base station that performs the same transmission power control with a combined link when a plurality of wireless links exist with a mobile device and the plurality of wireless links are combined between sectors. And means for performing DPCH (Dedicated Physical Channel) BER (Bit Error Ratio) measurement and TPC (Transmit Power Control) bit acquisition for each of the plurality of radio links, and the results of BER measurement and TPC bit acquisition. A radio base station comprising: means for performing the transmission power control and the TPC bit control based on the transmission power control.   Means for measuring the reception level and the BER of each sector when the TPC bit cannot be obtained and the transmission power control cannot be performed; means for weighting the radio link according to the measurement result of the BER; 7. A radio base station according to claim 6, further comprising means for performing transmission power control by performing inter-sector combination on said radio link and extracting said TPC bit.   8. The radio base station according to claim 7, further comprising means for performing the transmission power control when the BER is deteriorated and the TPC bits continuously indicate the same value.   An additional fixed bit set in advance in the DPCH is provided separately from a pilot part, and the BER is calculated and obtained for another fixedly determined bit by the additional fixed bit. The radio base station according to claim 6.   10. The radio base station according to claim 6, wherein the radio base station is used in a W-CDMA (Wideband Code Division Multiple Access) type radio communication system. 10.   A mobile device in which a plurality of radio links exist with a plurality of radio base stations, and when the plurality of radio links are combined between sectors, the same transmission power control is performed on the combined link. Means for performing DPCH (Dedicated Physical Channel) BER (Bit Error Ratio) measurement and TPC (Transmit Power Control) bit acquisition for each of the plurality of radio links, and BER measurement and TPC bit acquisition And a means for performing the transmission power control and the TPC bit control based on the result.   Means for measuring the reception level and the BER of each sector when the TPC bit cannot be obtained and the transmission power control cannot be performed; means for weighting the radio link according to the measurement result of the BER; The mobile station according to claim 11, further comprising means for performing transmission power control by performing inter-sector combining on the radio link that has performed and extracting the TPC bit.   The mobile device according to claim 12, further comprising means for performing the transmission power control when the BER is deteriorated and the TPC bits continuously indicate the same value.   An additional fixed bit set in advance in the DPCH is provided separately from a pilot part, and the BER is calculated and obtained for another fixedly determined bit by the additional fixed bit. The mobile device according to any one of claims 11 to 13.   The mobile device according to any one of claims 11 to 14, wherein the mobile device is used in a W-CDMA (Wideband Code Division Multiple Access) wireless communication system.   In a wireless communication system in which a plurality of wireless links exist between a plurality of wireless base stations and a mobile device, transmission power for performing the same transmission power control on the combined link when the plurality of wireless links are combined between sectors In the control method, a BER (Bit Error Ratio) measurement of DPCH (Dedicated Physical Channel) and a TPC (Transmit Power Control) bit are combined in the inter-sector combination on each of the plurality of radio base stations and the mobile device. Performing acquisition for each of the plurality of radio links, and performing the transmission power control and the TPC bit control based on a result of the BER measurement and the acquisition of the TPC bit. Transmission power control method.   Measuring the reception level and the BER of each sector when the TPC bits cannot be obtained and the transmission power control cannot be performed on the plurality of radio base stations and the mobile devices, respectively, and the measurement of the BER And weighting the radio link according to a result, and performing transmission power control by combining the sectors and extracting the TPC bit in the weighted radio link. Item 17. A transmission power control method according to Item 16.   The step of performing the transmission power control on the side of each of the plurality of radio base stations and the mobile device when the BER deteriorates and the TPC bits continuously show the same value. 18. The transmission power control method according to 17.   An additional fixed bit set in advance in the DPCH is provided separately from a pilot part, and the BER is calculated and obtained for another fixedly determined bit by the additional fixed bit. The transmission power control method according to any one of claims 16 to 18.   The transmission power control method according to any one of claims 16 to 19, wherein the wireless communication system is a W-CDMA (Wideband Code Multiple Access) system.

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