WO2003049322A1 - Dispositif de communication a diversite d'emission - Google Patents
Dispositif de communication a diversite d'emission Download PDFInfo
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- WO2003049322A1 WO2003049322A1 PCT/JP2001/010520 JP0110520W WO03049322A1 WO 2003049322 A1 WO2003049322 A1 WO 2003049322A1 JP 0110520 W JP0110520 W JP 0110520W WO 03049322 A1 WO03049322 A1 WO 03049322A1
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- common pilot
- antennas
- base station
- pilot signal
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
- H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
- H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
- H04B7/0621—Feedback content
- H04B7/0634—Antenna weights or vector/matrix coefficients
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Definitions
- the present invention relates to a cellular mobile communication system, and more particularly to a transmission diversity communication apparatus that performs closed-loop diversity control of phase and amplitude in a base station based on feedback information from a mobile station.
- a plurality of antennas are provided on the base station side, and the same transmission data signal, which performs different amplitude and phase control for each antenna based on feedback information from the mobile station, is transmitted along with the pilot signal.
- Sent from antenna The mobile station determines the amplitude and phase control amount of each antenna based on the pilot signal received from each antenna, multiplexes the feedback information including the amplitude and phase control amount into the uplink channel signal, and Send to Background art
- Figure 1 shows an example of a system using two transmission antennas.
- the pilot signal generation unit 11 of the base station 1 generates a common pilot signal used for the two transmission antennas 16-1 and 16-2.
- the pilot signal of each transmitting antenna has a pilot pattern P i, P 2 that is orthogonal to each other, and these are converted into the same downlink transmission data signal by the adders 14 11 and 14 12.
- P i, P 2 that is orthogonal to each other
- the receiving antenna 23 receives the pilot signals from the transmitting antennas 16_1 and 16-12, and the control amount calculation unit 21 transmits the received pilot signals to the receiving antenna 23 respectively.
- the multiplexing unit 12 multiplexes the feedback information into an uplink channel signal, and transmits the multiplexed information to the base station 1 from the antenna 24.
- a mode 1 for quantizing the weight coefficient w2 to 1 bit and a mode 2 for quantizing the weight coefficient w2 to 4 bits control is performed by transmitting 1-bit feedback information in each slot, and the control speed is high, but accurate control is not possible due to coarse quantization.
- mode 2 control is performed with 4-bit information, so higher-precision control can be performed.
- 1-bit feedback is transmitted in each slot, and 1-bit feedback information is transmitted in each slot. Therefore, if the fusing frequency is high, it cannot be followed and the characteristics are degraded.
- the control accuracy and the fading tracking speed have a trade-off relationship.
- the closed-loop transmit diversity method is applied to the base station of a cellular mobile communication system, the signals from each transmit antenna undergo independent fading and are ideally in-phase combined at the mobile station antenna position.
- gain improvement by combining is obtained. Therefore, the reception characteristics are improved, and the number of users that can be accommodated in one cell can be increased.
- Ideal here means that there is no transmission error of feedback information, control delay, channel response estimation error, and quantization error of control amount. In practice, these factors cause the characteristics to be lower than ideal. Deteriorates.
- the antenna spacing In order to obtain diversity gain according to the number of transmitting antennas, it is necessary to increase the antenna spacing so that the fusing correlation is sufficiently small. To keep the fading correlation sufficiently small at the base station, the antenna spacing must be about 20 wavelengths. Since one wavelength is about 15 cm in the 2 GHz band, antennas are installed at intervals of about 3 m. For this reason, when the number of transmitting antennas is increased, the area required for installing the antennas becomes large, and there is a problem that the installation becomes difficult when the antennas are installed on the roof of a building or the like. Here, it is necessary to consider that even if the number of transmitting antennas is increased, a large improvement in diversity gain cannot be obtained because the diversity gain saturates as the number of transmitting antennas increases.
- an object of the present invention is to reduce the base station antenna installation space on the base station side and increase the total transmission power of the common pilot signal when the number of transmitting antennas is increased based on the above-described problems. Suppress to prevent the accuracy of channel response estimation from each antenna from deteriorating.In addition, the mobile station side suppresses the increase in uplink feedback information, and transmits with less characteristic degradation even when the fusing frequency is high. An object of the present invention is to provide a diversity communication device.
- an object of the present invention is to perform the calibration associated with each base station antenna easily and efficiently in order to further improve the estimation accuracy of the channel response described above, and to provide the base station side with a special
- An object of the present invention is to provide a transmission diversity communication device that does not require a special calibration device or circuit.
- a common pilot commonly used by a plurality of mobile stations is provided.
- the base station transmits each signal from the base station using multiple antennas, and the mobile station transmits the signals from multiple base station antennas such that the phases of the received multiple common pilot signals are closer to each other.
- the base station is configured to receive the common pilot from a reference antenna among a plurality of antennas.
- the common pilot signal is alternately transmitted from the plurality of antennas other than the reference antenna, and the mobile station transmits the common pilot signal constantly transmitted from the reference antenna.
- the base station comprises the plurality of antennas as a reference antenna, a high correlation antenna having a high fading correlation with the reference antenna, and a low correlation antenna having a low fading correlation with the reference antenna.
- the common pilot signal is always transmitted from the reference antenna, and the transmission frequency of the common pilot signal is transmitted from the high correlation antenna to the high correlation antenna and the low correlation antenna.
- the common pilot signal is alternately transmitted from the low correlation antenna so as to increase the frequency of transmission of the common pilot signal, and the mobile station transmits the common pilot signal and the common pilot signal constantly transmitted from the reference antenna.
- Phase control information for controlling the phase of the highly correlated antenna is calculated from a common pilot signal transmitted from the highly correlated antenna infrequently, and the frequency is fed to the base station infrequently. Moni and when you back
- the base station includes a plurality of antennas including a reference antenna and a plurality of antennas other than the reference antenna.
- the reference antenna constantly transmits a common pilot signal, and the base station transmits signals other than the reference antenna.
- a common pilot signal is transmitted at a frequency corresponding to the phase control frequency from the mobile station.
- a common pilot signal used in common by a plurality of mobile stations is transmitted from a base station using a plurality of antennas, and the mobile station receives the plurality of common pilot signals.
- the phase control information for controlling the phase of a transmission signal transmitted from a plurality of antennas of the base station is fed back to the base station so that the phase of each of the transmission signals approaches each other.
- the plurality of antennas include a reference antenna and a plurality of antennas other than the reference antenna.
- the reference antenna always transmits a common pilot signal, and the plurality of antennas other than the reference antenna.
- a transmitting means for alternately transmitting a common pilot signal, and a base station having the following.
- the base station comprises the plurality of antennas as a reference antenna, a high-correlation antenna having a high fading correlation with the reference antenna, and a low-correlation antenna having a low fading correlation with the reference antenna, While transmitting the common pilot signal from the reference antenna at all times, the transmission frequency of the common pilot signal from the high correlation antenna is low for the high correlation antenna and the low correlation antenna, Transmission means for alternately transmitting the common pilot signal from the low correlation antenna so as to increase the frequency of transmission is provided.
- phase control of the highly correlated antenna is performed based on the phase control information received infrequently from the mobile station
- phase control of the low correlation antenna is performed based on the phase control information frequently received from the mobile station.
- Phase control Further comprising means.
- the base station comprises the plurality of antennas as a reference antenna and a plurality of antennas other than the reference antenna, and constantly transmits a common pilot signal from the reference antenna,
- the plurality of antennas have transmission means for transmitting a common pilot signal at a frequency corresponding to the phase control frequency from the mobile station.
- a common pilot signal used in common by a plurality of mobile stations is transmitted from a base station using a plurality of antennas, respectively, and the mobile station receives a plurality of received common pilot signals.
- a mobile communication system that performs transmission diversity that feeds back to the base station phase control information that controls the phase of transmission signals transmitted from multiple antennas of the base station so that the phases of the pilot signals approach each other.
- the plurality of antennas are constituted by a reference antenna and a plurality of antennas other than the reference antenna, a common pilot signal constantly transmitted from the reference antenna, and the reference antenna Receiving means for receiving a common pilot signal transmitted alternately from a plurality of antennas other than the common antenna, and a common pilot signal received by the receiving means
- a mobile station having phase control means for calculating phase control information for each of a plurality of antennas other than the reference antenna from the reference signal.
- phase control unit receives a common pilot signal transmitted constantly from a reference antenna and a common pilot signal transmitted alternately from a plurality of antennas other than the reference antenna, Calculate phase control information for multiple antennas other than the reference antenna.
- the plurality of antennas include a reference antenna, a high correlation antenna having a high fading correlation with the reference antenna, and a low correlation antenna having a low fading correlation with the reference antenna.
- the common pier always transmitted from the reference antenna
- the phase control information for controlling the phase of the highly correlated antenna is calculated from the common pilot signal transmitted by the common antenna and the common pilot signal constantly transmitted from the reference antenna and the low frequency antenna from the low correlation antenna.
- phase control means for calculating phase control information for controlling the phase of the low-correlation antenna from the transmitted common pilot signal.
- FIG. 1 is a diagram showing a configuration example of a conventional closed-loop transmission diversity system using two transmission antennas.
- FIG. 2 is a diagram showing a first configuration part in the closed loop diversity communication device of the present invention.
- FIG. 3 is a diagram illustrating a configuration example of a transmission antenna in the base station in FIG.
- FIG. 4 is a diagram showing a configuration example of a base station transmitting antenna used in a second configuration part in the closed loop diversity communication device of the present invention.
- FIG. 5 is a diagram showing a basic configuration of a closed-loop diversity communication device according to the present invention.
- FIG. 6 is a diagram illustrating a configuration example of a transmission antenna in the base station of FIG. 5,
- FIG. 7 is a diagram showing a specific example of FIG.
- FIG. 8 is a diagram showing the switching format of the common pilot signal and the transmission format of the feedback information in FIG. BEST MODE FOR CARRYING OUT THE INVENTION
- FIG. 2 shows a first configuration part in the closed loop diversity communication device of the present invention.
- FIG. 3 shows a configuration example of a transmitting antenna in the base station of FIG.
- This first component mainly solves the above-mentioned problems (1) and (2).
- base station 1 has N transmitting antennas with the number of transmitting antennas expanded to 3 or more. ⁇ 16-N are provided.
- the pilot signal generator 11 generates N mutually orthogonal pilot signals P t), P 2 (t),..., P N (t), and adds them. Part 1 4— :! ⁇ 14-N and added to the same transmission data signal and transmitted from different transmission antennas 16-:! ⁇ 16-N.
- Each of the pilot signals undergoes amplitude and phase fluctuations due to fading, and these combined signals are received by the receiving antenna 23 of the mobile station 2.
- the control amount calculation unit 21 of the mobile station 2 sends a P! (t), P 2 (t), ⁇ ⁇ ⁇ , and P N (t), the channel impulse response vectors 1 ⁇ , h 2 , ⁇ ⁇ , h N is estimated.
- each transmitting antenna 16-of the base station 1 that maximizes the power P expressed by the following equation (4):!
- W [W 2,..., W N ] is decremented and the result is quantized.
- H [h 2 ,..., H N ] (5)
- hi the channel impulse response vector from the transmitting antenna i.
- L the length of the impulse response
- base station 1 divides the total N transmission antennas into multiple groups (M) including multiple antennas (K) as shown in Fig. 3, and transmits K transmission antennas in each group.
- M multiple groups
- K multiple antennas
- the antenna control amount between groups (F ⁇ F ⁇ M), antenna control amount in the group fast (GU G ⁇ K, ⁇ , G M, 2 ⁇ G M, ⁇ ) good Ri also Calculate periodically and transmit these to the base station as feedback information.
- one antenna in each group is referred to as a reference antenna (# 1, # (K + 1),..., # ( ⁇ -1) ⁇ + 1), and antennas in the group other than the reference antenna are referred to.
- control amount (Gj, SGK, ⁇ , G M, 2 ⁇ G M, K) and normalized by the control amount of the reference antenna.
- the reference antenna control amount of one specific group The normalization of the reference antenna control amounts of the other groups is defined as the inter-group antenna control amount.
- the reference antenna # 1 of group 1 is normalized, and the antenna between it and the other reference antennas of groups 2 to M (# (K + 1),..., # (M—l) K + 1)
- the control amount is defined as the inter-group antenna control amount (F ⁇ Fu). Since the inter-group antenna control amount (F ⁇ FLM) fluctuates at high speed due to independent fusing fluctuations, it is necessary to perform control in a short cycle for accurate control.
- the signals from the base station transmitting antennas in the same group have almost the same fading because of high fading correlation, but move with a phase difference according to the angle of mobile station 2 with respect to base station 1. It reaches the receiving antenna 23 of the station. Therefore, channel response estimation values estimated using signals from base station transmission antennas in the same group have a phase difference corresponding to the angle of mobile station 2 with respect to base station 1. These values change with the movement of the mobile station 2, but the characteristic is that they fluctuate more slowly than the fading fluctuations.
- one antenna in each group is set as a reference antenna (# 1, # (K + 1),..., # (M-1) K + 1), and control of antennas in the group other than the reference antenna is performed. the amount (G ⁇ Gi.
- G ⁇ GK, ⁇ , G M. 2 ⁇ G M. K The normalized in the group antenna control amount (G ⁇ GK, ⁇ , G M. 2 ⁇ G M. K) varies with Gently with the movement of the mobile station. Therefore, the control cycle can be made relatively long.
- the inter-group antenna control amounts F and ⁇ and the intra-group antenna control amounts G N and K shown in FIG. 3 are obtained by the following equations (7) and (8).
- M is the number of antenna groups
- K NZM is the number of antennas in each group. * Represents a complex conjugate.
- the transmission antenna groups are grouped, and the antenna spacing is set between the groups in order to suppress the fusing correlation sufficiently small.
- antennas are installed at intervals of about one wavelength to enhance fading correlation. This has the advantage that the base station antenna installation space can be reduced despite the increase in the number of transmitting antennas.
- the amount of antenna control in each group has a value corresponding to the angle of the mobile station 2 with respect to the base station 1, in a macrocell system in which the cell radius is somewhat large, the deviation in the angle of arrival is small enough to be ignored Obviously, a specific intra-group antenna control amount (for example, G i, 2 to G !, ⁇ of group 1) is replaced by an antenna control amount within a group of another group (G 2 , 2 to G 2, K, ⁇ ⁇ , can also Mochiiruko to G M, 2 ⁇ G M, K ) and. In other words, only control information within a group of one group is transmitted, and the other group is used by using the copy information.
- G i, 2 to G !, ⁇ of group 1 is replaced by an antenna control amount within a group of another group (G 2 , 2 to G 2, K, ⁇ ⁇ , can also Mochiiruko to G M, 2 ⁇ G M, K ) and.
- the amount of feed pack information can be reduced by controlling the number of antennas.
- FIG. 4 shows a configuration example of a base station transmitting antenna used in a second configuration part in the closed loop diversity communication device of the present invention.
- This second component mainly solves the above-mentioned problem (3). It should be noted that the block configuration itself of the second component is the same as that of FIG.
- base station 1 has all inter-group antenna control amounts 2 F ⁇ M for reference antenna # 1 of group 1 described above and an antenna adjacent to reference antenna # 1 of group 1.
- feed pack information shown by the dotted frame in the figure
- the necessary pilot signals P i, ⁇ ⁇ + , ⁇ ( ⁇ - 1) transmits kappa + 1 and [rho 2 only to the mobile station 2.
- the second component of the present invention when the number of transmitting antennas in base station 1 is increased, when the transmission power of the common pilot signal per transmitting antenna is constant, Since the total transmission power of the common pilot signal is moderately increased, the amount of interference of the common pilot signal on the data signal in a multipath environment can be reduced. On the other hand, if the total transmission power of the common pilot signal is kept constant at base station 1, the decrease in the transmission power of the common pilot signal per transmission antenna becomes moderate, and the response of each channel response is reduced. A decrease in estimation accuracy is avoided.
- FIG. 5 shows a basic configuration of a closed loop diversity communication device according to the present invention.
- FIG. 6 shows a configuration example of a base station transmitting antenna used in the basic configuration of the closed loop diversity communication device of the present invention.
- This configuration includes the above-described first and second components according to the present invention.
- items of the problem (4) Solve in addition to the above-mentioned problems (1) to (3), items of the problem (4) Solve.
- the base station 1 transmits only the common pilot signal necessary for generating the reduced feedback information.
- necessary information and power are reduced by using a method in which an antenna control amount for one antenna is used as an antenna control amount for another antenna. This method works ideally when the plurality of transmitting antennas 16-1 to 16_N in the base station 1 all have the same circuit characteristics.
- the antenna control within a specific group of the base station 1 as in the first or second component of the present invention Kik ⁇ 2,..., K) and all the inter-group antenna control amounts F ⁇ m: 2,..., M) are calculated from the channel response estimation values by the common pilot signal, and For other groups, the antenna control amount in a specific group can be used.
- the principle of the closed-loop transmit diversity system is that the mobile station 2 correlates the received pilot signal with each known pilot signal, thereby allowing each transmit antenna 16-1- Estimate the channel response from 16—N to mobile station 2 and use this estimated channel response to determine the transmit antennas of base station 1 1 6— :! ⁇ 16—Perform N-phase and amplitude control And
- the estimated value of the channel response corresponds to a combination of the actual channel response and the phase / amplitude deviation of the transmitting antenna. Therefore, in the original closed-loop transmission diversity system, phase / amplitude control for diversity combining and phase / amplitude control in calibration are performed in an integrated manner. Therefore, it is not necessary to add a separate device for the calibration.
- the transmitted pilot signal is a common pilot signal ⁇ + 1 , ..., ⁇ from the reference antenna of each group. ( ⁇ ) ⁇ + ⁇ and only the common pilot signal ⁇ 2 from adjacent antennas in group 1. Therefore, the antenna systems to be calibrated by the original closed-loop transmit diversity method described above are the reference antennas # 1, # (K + 1), ⁇ , and # ( ⁇ -1) K of each group. +1 and antenna # 2. Therefore, when the second component according to the present invention is actually applied, it is necessary to add a separate calibration circuit for antennas other than those described above, which causes a problem that the circuit scale increases.
- the basic configuration of the present invention shown in FIG. 5 mainly solves this problem.
- sweep rate pitch the new base station 1 to the configuration of FIG. 2 (SW n ⁇ SW N) 1 8- n ⁇ 1 8 _ N and the multiplier 1 9-1, 1 9-n to 1 9—N has been added.
- the transmitting antennas are divided into a plurality of groups composed of a plurality of antennas, and the transmitting antennas in each group are close to each other so that the fading correlation becomes high. They should be placed at a distance from each other so that the fusing correlation between groups is low.
- N is the number of transmitting antennas
- M is the number of antenna groups
- the corresponding common pilot signal ⁇ 2 from the antennas # 2 to #K other than the reference antenna # 1 ⁇ ⁇ ⁇ is transmitted.
- a common pilot signal is always transmitted from the reference antennas of each group, while a common pilot signal is transmitted once within a fixed time period from all antennas other than the reference antennas in each group.
- Switches 18-2 to 18 _ ⁇ are controlled to open and close so that a pilot signal is transmitted. The reason for the fixed time period is that the phase / amplitude deviation of each antenna fluctuates very slowly individually over time.
- the original closed-loop transmit diversity can carry out calibration for all antenna systems, and the phase / amplitude deviation (eie MK) of each antenna system becomes equal to the antenna. It is corrected by the multipliers 19-1 to 19-1 MK provided for each.
- Each of the pilot signals receives amplitude and phase fluctuations due to fading, and these combined signals are input to the receiving antenna 23 of the mobile station 2.
- the control amount calculation unit 21 of the mobile station 2 obtains the correlation between each received pilot signal and each pilot signal known by the mobile station 2, thereby obtaining each transmission signal of the base station 1. It is possible to estimate the channel impulse response vectors h,..., h MK from antennas 16 —;!
- the power P intergr given by equation (9) for the reference antenna in each group.
- W intergroup Lw w K + 1 , ..., w ( M i) ⁇ + 1].
- W intergroup Lw w K + 1 , ..., w ( M i) ⁇ + 1].
- W intergroup Lw w K + 1 , ..., w ( M i) ⁇ + 1].
- it is set to 1.
- the amplitude of the transmission antennas to maximize the up and position phase control vector (weight vector) W intragr. up [w (n _! ) ⁇ + 1 ,
- W (m-1) K + k W (m-1) K + k ].
- W ( ⁇ ) ⁇ + is W inter _ gr . using the values obtained in the calculation of u p.
- H inter_group [h 11 ⁇ 2 +1 , .. ⁇ , h (M _ 1) K + 1 ] (10)
- ⁇ intra group ⁇ h (m — 1) K + 1 , h ( m — 1) K + k ] (12)
- the inter-group weight vector W intergr obtained in this way. the weight of the u p and the group vector w int ra gr.
- the inter-group antenna control amount is every time calculation according to the common pie Lock preparative signals that will be sent every time from each group of criteria antenna, the in-group antenna control amount G m. K is each time the It is calculated according to the common pilot signal sent from any antenna other than the reference antenna of the group.
- the inter-group antenna control amounts were set to fast fading fluctuations and extremely loose phase and amplitude deviations of the transmitting antennas.
- ⁇ group antenna control amount G m, for k the variation was Ri relatively slowly angle of the mobile station 2 to the base station 1
- the transmission antenna Phase 'feedback is relatively infrequent enough to track both very slow variations in amplitude deviation.
- the base station 1 holds the antenna control amount that has been fed back in the buffer in the buffer, and updates the buffer information every time a new antenna control amount is fed back.
- the phase and amplitude control of the transmission data is performed by the antenna control amounts F i .B and G ⁇ , k held in the buffer.
- a common pilot signal is transmitted from all reference antennas every time, and For antennas other than the quasi-antenna, a common pilot signal is sequentially selected from any of the antennas and transmitted. Therefore, even when the number of transmitting antennas is increased at the base station 1, the common pilot signal is increased. The number of antennas that transmit the signal can be limited. Therefore, when the transmission power of the common pilot signal per transmission antenna is constant, the total transmission power of the common pilot signal increases moderately, and the common pilot signal is used in a multipath environment. Therefore, the amount of interference that the data signal gives to the data signal can be suppressed.
- the phase and amplitude deviation of the transmitting antenna can be corrected without adding a special calibration circuit.
- the transmission diversity communication apparatus having the basic configuration of the present invention has a small base station antenna installation space on the base station side when the number of transmission antennas is increased, and reduces the total transmission power of the common pilot signal. This suppresses the increase, prevents the accuracy of channel response estimation from each antenna from deteriorating, and suppresses the increase in uplink feedback information on the mobile station side. Communication with each base station antenna, which further enhances the accuracy of channel estimation, can be performed easily and efficiently, and a special carrier is provided to the base station side. There is no need to provide a braking device or circuit.
- FIG. 7 and 8 show a specific embodiment of FIG.
- Fig. 8 shows the switching format of the common pilot signal from the base station and the transmission format of the feedback information from the mobile station. It shows the relationship with
- antenna # 1 and antenna # 2 of base station 1 are group 1, and antenna # 3 and antenna # 4 are group 2. Also, antenna # 1 and antenna # 3 are used as reference antennas in groups 1 and 2, respectively. Antennas # 1 and # 2, and antennas # 3 and # 4 are each separated by one wavelength so that the fading correlation is high. Antennas # 1 and # 3, and antennas # 2 and # 4 are spaced apart by 20 wavelengths so that the fading correlation is sufficiently small. Sequences P i, P 2 , P 3, and P 4 orthogonal to each other are used as common pilot signals. Reference antenna # 1 of the antenna group 1 and 2, from # 3 to send each time the common pi Lock preparative signals P, P 3, respectively.
- the other antenna # 2, from # 4, depending on the state of Sui Tsu switch SW 2, SW 4, respectively, may or may not send the common pie Lock preparative signals P 2, P 4.
- the common pilot signals, P 2 , P 3 , and P 4 are affected by the phase of the transmitting antenna, the amplitude deviations e, e 2 , e 3 , and e 4 , and the amplitude and phase fluctuations due to fading.
- the combined signal is input to the receiving antenna 23 of the mobile station 2.
- Figure 8 shows an example of using the W-CDMA frame format (one frame of 10 ms length is composed of 15 slots).
- the switching format of the common pilot signal corresponds to the transmission format of the feedback pack information, and is sufficient for the mobile station to calculate the feedback information.
- sweep rate pitch SW 2, SW 4 is switched.
- the base station 1, 1 frame, 1 5 scan B Ssu Lock bets of bets 4, 7, 1 1, and 1 4 sweep rate pitch S w 2 and in sw 4 is switched on alternately. Switching of these switches is performed at the direction of the upper layer.
- the feedback information extraction unit 13 of the base station 1 extracts the feedback information received on the uplink channel, and the amplitude / phase control unit 12 responds based on the feedback information received on the immediately preceding reception slot.
- antenna weights W n controls the W B 1 and W B2 directly.
- the amplitude / phase control unit 12 holds the feedback information that is temporally recent and uses it for control. With this control, phase and amplitude control for diversity synthesis and correction of the phase and amplitude deviation of each antenna are performed in an integrated manner.
- the mobile station 2 has calculated the antenna control amount based on the received common pilot signal, but as another calculation method, even if the common pilot signal is not transmitted, the downlink transmission data is calculated. It is also possible to calculate the amount of antenna control using the user-specific pilot signal included in the signal.
- the individual pilot signals are time-multiplexed with the data signal, and the SIR (Signal to Interference Ratio) estimation for transmission power control and RAKE combining It is used for channel estimation and so on.
- the channel estimation value is obtained by correlating with the known common pilot signal as shown in the following equation (17).
- the antenna control amount is calculated using this to obtain the diversity for the base station for diversity combining.
- Phase / amplitude control and correction of phase / amplitude deviation of each antenna are possible.
- the principle of calculating the in-group antenna control amount using the individual pilot signal in mobile station 2 will be described. I do.
- the received signal components of the individual pilot signals from antennas # 1 # 2 # 3 # 4 are expressed by the following equations (18) and (21), respectively.
- the receiving side correlates the known individual pilot signal with the antenna control amount that was fed back immediately before, as shown in the following equations (22) and (25), so that the channel response and the base station A channel estimation value corresponding to a combination of the phase and amplitude deviation of the transmitting antenna is obtained.
- the mobile station 2 uses the individual pilot signals to calculate the intra-group antenna control amount, whereby the common pilots of antennas # 2 and # 4 are obtained.
- Lock door signal P 2 and P 4 is that Do not required. Therefore, the this be reduced to the al total transmit power of the common pi Lock preparative signal to turn off the sweep rate pitch SW 2 and SW 4 in Figure 7 always be possible in the base station 1 side.
- the transmission power is further increased as in the embodiment of FIG. and also sends the channel estimation common pi Lock preparative signal P 2 small error, P 4 calculates the intra-group antenna control amount of both individual pie Lock preparative signal and the common pi Lock preparative signal. Since the intra-group antenna control amount fluctuates relatively slowly, the accuracy of the intra-group antenna control amount can be further improved by averaging all of them.
- the frequency of transmitting a common pilot signal from each antenna is not fixed as in the example of FIG. Change.
- the change in the angle of the mobile station with respect to the base station is not so sharp (in a macrocell environment), but the fading fluctuation becomes more severe.
- the inter-group antenna control amount is more frequently packed so that it can follow fading fluctuations.
- slots 4 and 11 relating to antennas # 2 and # 4 of FIG. 8 (a) Are changed to slots for reference antennas # 1 and # 3. If the fading correlation in each group is not large, the antenna control amount in the loop also fluctuates according to the fading, so that the group antenna control amount is fed back more frequently.
- the slots for antennas # 2 and # 4 in one frame are increased to slots 3, 5, 8, 10, 13, and 15 Let me.
- the switching of the switching format is determined by the instruction of the upper layer.
- the present invention by reducing the number of antennas for transmitting the common pilot signal necessary for obtaining control information, when the number of transmitting antennas is increased in the base station, If the transmission power of the common pilot signal per transmission antenna is constant, the amount of interference that the common pilot signal gives to the data signal in a multipath environment is reduced, and the common pilot signal If the total transmit power is constant, the accuracy of estimation of each channel response can be prevented from deteriorating, and a special calibration circuit for correcting the phase and amplitude deviation of the transmitting antenna is not required. The effect of is obtained.
Description
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PCT/JP2001/010520 WO2003049322A1 (fr) | 2001-11-30 | 2001-11-30 | Dispositif de communication a diversite d'emission |
JP2003550394A JPWO2003049322A1 (ja) | 2001-11-30 | 2001-11-30 | 送信ダイバーシチ通信装置 |
EP01274899A EP1453223A1 (en) | 2001-11-30 | 2001-11-30 | Transmission diversity communication device |
US10/859,743 US20050014474A1 (en) | 2001-11-30 | 2004-05-28 | Transmission diversity communication system |
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PCT/JP2001/010520 WO2003049322A1 (fr) | 2001-11-30 | 2001-11-30 | Dispositif de communication a diversite d'emission |
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US10/859,743 Continuation US20050014474A1 (en) | 2001-11-30 | 2004-05-28 | Transmission diversity communication system |
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US (1) | US20050014474A1 (ja) |
EP (1) | EP1453223A1 (ja) |
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Also Published As
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US20050014474A1 (en) | 2005-01-20 |
EP1453223A1 (en) | 2004-09-01 |
JPWO2003049322A1 (ja) | 2005-04-21 |
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