WO2016155502A1 - 无线通信系统中执行干扰协调的方法和设备 - Google Patents

无线通信系统中执行干扰协调的方法和设备 Download PDF

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WO2016155502A1
WO2016155502A1 PCT/CN2016/076486 CN2016076486W WO2016155502A1 WO 2016155502 A1 WO2016155502 A1 WO 2016155502A1 CN 2016076486 W CN2016076486 W CN 2016076486W WO 2016155502 A1 WO2016155502 A1 WO 2016155502A1
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terminal
signal
base station
serving
arrival
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PCT/CN2016/076486
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French (fr)
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吴亮
张在琛
党建
于莹莹
秦伟微
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索尼公司
吴亮
张在琛
党建
于莹莹
秦伟微
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Priority to EP16771257.9A priority Critical patent/EP3280221A4/en
Priority to US15/560,186 priority patent/US10277348B2/en
Publication of WO2016155502A1 publication Critical patent/WO2016155502A1/zh

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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
    • H04B7/0413—MIMO systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J11/00—Orthogonal multiplex systems, e.g. using WALSH codes
    • H04J11/0023—Interference mitigation or co-ordination
    • H04J11/0026—Interference mitigation or co-ordination of multi-user interference
    • H04J11/0036—Interference mitigation or co-ordination of multi-user interference at the receiver
    • 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
    • H04B7/022—Site diversity; Macro-diversity
    • H04B7/024—Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
    • 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
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/16—Performing reselection for specific purposes
    • H04W36/20—Performing reselection for specific purposes for optimising the interference level
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/50—Allocation or scheduling criteria for wireless resources
    • H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
    • H04W72/541—Allocation or scheduling criteria for wireless resources based on quality criteria using the level of interference
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/08—Access point devices
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0003—Two-dimensional division
    • H04L5/0005—Time-frequency
    • H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT
    • H04L5/001—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT the frequencies being arranged in component carriers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/02—Arrangements for optimising operational condition
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/16—Performing reselection for specific purposes
    • H04W36/165—Performing reselection for specific purposes for reducing network power consumption

Definitions

  • the present invention relates to a method and apparatus for performing interference coordination in a wireless communication system, and more particularly to a method and apparatus for estimating an angle of arrival of a signal transmitted by a user terminal and using the angle of arrival for interference coordination.
  • small base stations In order to adapt to the rapid growth of mobile data traffic, the deployment of small base stations is the trend of future wireless communications. Small base stations can help manage and use existing wireless spectrum resources more efficiently. Compared with the macro base station, the coverage area of the small base station is smaller, the space utilization of the spectrum is higher, and the layout is more flexible. In the future, there may be many small cells served by small base stations in the coverage area of each macro base station.
  • the interference users may be users of other small base station services. It may also be a user of the macro base station service. If all users in the coverage area of the small base station are divided into a service user set and an interference user set, each set may contain multiple users. Interfering with a user set is a collection of signals that need to be suppressed, while a set of service users is hoping to maintain a collection of their signals, and it is desirable to implement multi-user communication that does not affect each other in the service user set. Therefore, interference coordination between small base stations and between small base stations and macro base stations has an extremely important impact on the management of the entire wireless network.
  • the interference coordination technology mainly reduces the interference between adjacent cells by coordinating the use of different communication resources between different base stations.
  • the existing technology is mainly considered from the following three aspects: frequency domain, time domain and power control.
  • the neighboring cells mainly use orthogonal spectrum resources to allocate different frequency reuse sets to users at the cell center and the cell edge, thereby improving the communication performance of the cell edge users, or
  • the orthogonal subcarrier resources are reasonably multiplexed on the basis of the intermodulation technique.
  • the subframe management is mainly performed, so that the interfering users are limited in load or completely unloaded in certain subframes, thereby protecting the reliable communication of the service users in these subframes.
  • Power control techniques improve the quality of communications by sacrificing part of the throughput performance, for example by reducing the transmit power of interfering base stations to ensure the communication performance of the interfered users. Although these three technologies help to reduce interference, they sacrifice the performance of other aspects of the system to some extent.
  • the pattern of the array can be changed by adjusting the weighting coefficients of each array element so that the beam always points to the direction of arrival (DOA) of the user signal, and the zero point is aligned with the interference signal, thereby realizing automatic beam following.
  • User signal The technology improves the gain and signal-to-noise ratio of the antenna, so that the user quantity can be expanded under the same frequency domain, the same time slot and the same code group, which is an effective way to solve the current shortage of frequency domain resources and improve communication capacity.
  • Conventional angle of arrival estimation techniques include subspace class arrival angle estimation algorithms, such as MUSIC and ESPRIT. However, these algorithms can only estimate the angle of arrival of all signals arriving at the antenna array, but cannot obtain the angle of arrival corresponding to the signal of each specific user terminal. Therefore, the base station cannot avoid other user terminals well in downlink transmission. Interference.
  • a method of processing interference coordination in a communication system comprising a plurality of user terminals, the method comprising: determining, by the information obtained from the user terminal, by the The angle of arrival of the signal transmitted by the user terminal, and the user terminal requiring service according to the angle of arrival of the signal of the user terminal.
  • a method for receiving a signal in an uplink at a base station side comprising: determining an angle of arrival of a signal of each of a serving terminal and an interfering terminal within a coverage area of a base station
  • the signal of the serving terminal is initially restored based on the angle of arrival of the signal of the serving terminal; and at the multiple input multiple output (MIMO) layer, the signal of the serving terminal is restored again based on the initial recovered signal.
  • MIMO multiple input multiple output
  • a method for transmitting a signal in a downlink at a base station side comprising: determining an angle of arrival of a signal of each of a serving terminal and an interfering terminal within a coverage area of a base station Determining a transmission weight vector for the serving terminal based on the determined angle of arrival of the signal of the serving terminal; transmitting a signal for the serving terminal by weighting the signal for the serving terminal using the determined transmission weight vector.
  • a base station in a communication system comprising a plurality of user terminals, the base station comprising one or more processors, the one or more processors being configured to Determining an angle of arrival of a signal transmitted by the user terminal based on information acquired from the user terminal, and selecting a user terminal requiring service based on an angle of arrival of the signal of the user terminal.
  • the one or more processors are further configured to: initially recover a signal of the serving terminal based on an angle of arrival of the signal of the serving terminal at the smart antenna layer; and based on the initial recovery at a multiple input multiple output (MIMO) layer The signal restores the signal of the service terminal again.
  • MIMO multiple input multiple output
  • the one or more processors are further configured to: determine a transmit weight vector for the serving terminal based on the determined angle of arrival of the signal of the serving terminal; and perform a signal for the serving terminal using the determined transmit weight vector Weighted.
  • FIG. 1 is a schematic diagram showing a wireless communication system in which a large number of small base stations are deployed;
  • FIG. 5 schematically shows a frame structure of a signal transmitted by a user terminal
  • Figure 6 is a schematic illustration of the processing of a smart antenna layer and a MIMO layer in an uplink transmission
  • Figure 7 is a schematic illustration of the processing of the smart antenna layer and the MIMO layer in downlink transmission
  • FIG. 8 illustrates a signaling interaction flow of an uplink transmission according to an embodiment of the present invention
  • FIG. 9 illustrates a signaling interaction procedure of an uplink transmission according to another embodiment of the present invention.
  • Figure 10 illustrates a signaling interaction flow for downlink transmissions in accordance with the present invention
  • 11 is a block diagram showing an example configuration of computer hardware.
  • MIMO Multiple Input Multiple Output
  • the channel characteristics of the uplink and downlink are reciprocal within the coherence time, so the base station can use the uplink channel information to estimate the channel state and use the estimated channel state for the channel state. Precoding of downlink transmissions.
  • the channel characteristics of the uplink and downlink do not have reciprocity, and the user terminal needs to estimate the downlink channel state information according to the pilot information sent by the base station and feed back to the base station, and the base station according to the feedback channel Status information for precoding processing.
  • the pilot overhead for estimating downlink channel state information increases linearly, and the amount of information fed back by the user terminal also increases linearly.
  • FIG. 1 schematically shows a wireless communication system to which the present invention is applied, which system includes a macro base station 100, a plurality of small base stations 210-250 located in a coverage area of the macro base station 100, and a plurality of user terminals 300.
  • user terminal 300 can include user terminals served by macro base station 100 and user terminals served by small base stations 210-250. Further, the user terminal 300 may include various portable mobile communication terminals such as a mobile phone, a notebook computer, and the like.
  • the dark arrows in the figure show the communication link between the macro base station or each small base station and the user terminal it serves, and the light (hollow) arrows show the macro base station or each small base station and the service users that do not belong to it.
  • the other user terminals of the terminal are mutually interfering communication links.
  • the small base stations 210-250 serve the user terminals in the range of tens of meters to several hundred meters with a lower transmission power. Due to the large number of small base stations, interference coordination management between adjacent small base stations and between small base stations and macro base stations is critical to the communication performance of the system. For example, it is assumed that when the small base station 210 is in an active state, a user terminal served by another neighboring small base station or a user terminal served by the macro base station (hereinafter collectively referred to as "interfering user terminal" or "interfering terminal”) enters the small base station 210.
  • the coverage area at this time, the small base station 210 and the interfering user terminals may interfere with each other's communication.
  • the small base station 210 will be subject to interference from these interfering user terminals; in the downlink, these interfering user terminals will be interfered by signals transmitted by the small base station 210.
  • the present invention proposes a method of implementing interference coordination and communication for multi-cell and multi-user by estimating the angle of arrival of signals transmitted by each user terminal.
  • FIG. 2 shows a case where there is interference between the small base station 210 and the small base station 220. As shown in FIG. 2, there is an overlapping coverage area between the small base station 210 and the small base station 220.
  • the small base station 210 detects a change in the state of the user in its coverage area (including the generation of a new service user, the interference occurs due to the service user of the small base station 220 entering the coverage area of the small base station 220)
  • the small base station 210 will estimate each The angle of arrival of the signal sent by the user, And through the signaling interaction with the small base station 220 to determine which arrival angles belong to the service user terminal, and which arrival angles belong to the interference user terminal. After estimating the angle of arrival of all user terminals transmitting signals, interference coordination and multi-user communication are performed between these service user terminals and the interfering user terminals.
  • FIG. 3 shows a case where there is interference between the small base station 210 and the macro base station 100.
  • the small base station 210 is located in the coverage area of the macro base station 100.
  • the small base station 210 detects a change in the user state in its coverage area (including the generation of a new service user, the interference occurs due to the service user of the macro base station 100 entering its own coverage area)
  • the small base station 210 will estimate each user.
  • the angle of arrival of the terminal signals, and by signaling interaction with the macro base station 100 determines which angles of arrival belong to the serving user terminal and which angles of arrival belong to the interfering user terminal. After the arrival angles of all user terminal signals are estimated, interference coordination and multi-user communication are performed between these service user terminals and the interfering user terminals.
  • FIG. 4 shows a case where there is interference between the macro base station 100 and the macro base station 110.
  • the macro base station 100 detects a change in the state of the user in its coverage area (including the generation of a new service user, the interference occurs due to the service user of the macro base station 110 entering its own coverage area)
  • the macro base station 100 will estimate each user.
  • the angle of arrival of the terminal signals and by signaling interaction with the macro base station 110, determines which angles of arrival belong to the serving user terminal and which angles of arrival belong to the interfering user terminal. After the arrival angles of all user terminal signals are estimated, interference coordination and multi-user communication are performed between these service user terminals and the interfering user terminals.
  • the small base station 210 is taken as an example to describe how the small base station determines whether there is an interference user terminal in its coverage area.
  • the small base station 210 may receive information from the macro base station 100 indicating whether there is a user terminal served by the macro base station 100 or a neighboring small base station (e.g., the small base station 220, 250). When the information indicates that there is no user terminal served by the macro base station 100 or the neighboring small base station, the small base station 210 determines that there is no interfering terminal in its coverage area. When the information indicates that there is a user terminal served by the macro base station 100 or the neighboring small base station, the small base station 210 determines that there is an interfering terminal in its coverage area.
  • the small base station 210 determines that there is no interfering terminal in its coverage area, that is, only the service user terminal exists in its coverage area, in this case, the small base station 210 can directly estimate the arrival angle of the signal of each service user terminal. Realize communication of multiple users in the small cell.
  • the small base station 210 determines that there is an interfering user terminal in its coverage area, in addition to estimating the angle of arrival of the signal of the serving user terminal, the small base station 210 estimates the angle of arrival of the signal interfering with the user terminal, and then utilizes each of the estimated ones. The arrival angle of the user terminal to achieve interference coordination and service User communication.
  • Data transmission is divided into uplink transmission and downlink transmission according to different data transmission directions within the network.
  • the signals transmitted in the uplink are referred to as uplink signals, and the signals transmitted in the downlink are referred to as downlink signals, which are described separately below.
  • the uplink signals received by the small base stations y 0 can be expressed as follows:
  • An uplink steering vector representing the i-th user terminal is mainly determined by the antenna array model of the small base station, the wavelength and the angle of arrival of the signal transmitted by the user terminal.
  • the antenna array is an M ⁇ N matrix
  • ⁇ up is the wavelength of the uplink signal
  • ⁇ up c/f up
  • c is the speed of light
  • f up is the carrier frequency of the uplink
  • ⁇ i are the arrival azimuth and elevation angle of the signal transmitted by the ith user terminal, respectively
  • the uplink steering vector of the ith user terminal can be expressed as Where (x n , y n ) represents the position of the nth array element in the entire antenna array.
  • ⁇ i in the above equation represents the channel gain from the ith user terminal to the antenna array.
  • s i represents the signal transmitted by the ith user terminal, and
  • n represents the noise received by the antenna array.
  • the above shows the representation of the uplink signal y 0 received by the small base station.
  • Two methods for estimating the angle of arrival of the user terminal signal based on the spread signal proposed by the present invention will be described below.
  • subscript 1 ⁇ N 1 represents the service terminal
  • subscript (N 1 +1) ⁇ (N 1 + N 2) represent an interfering terminal.
  • M x N antennas are disposed on the small base station side, and these antennas constitute a planar array, and each user terminal has one antenna.
  • the signal transmitted by the i-th user terminal can be expressed as the following equation:
  • the angle of arrival estimation method estimates the angle of arrival of the signal using the first L (e.g., L ⁇ 50) symbols in the data to be transmitted by each user terminal.
  • L e.g., L ⁇ 50
  • the value of L is too large to increase the system overhead, and when L ⁇ 50, the system performance is small as L increases, so it is recommended to take a smaller value in this range.
  • each user terminal uses a random orthogonal code to spread the first L symbols in the data to be transmitted, and then transmits a symbol sequence including the extended first L symbols and the unexpanded G-L symbols.
  • Fig. 5 schematically shows the frame structure of a signal transmitted by a user terminal.
  • the extended signal of the i-th user terminal can be expressed as follows:
  • I the extension code used by the i-th user terminal.
  • Q represents the extended length (Q ⁇ K).
  • the i-th transmission signal of the user terminal may be expressed as a sequence comprising an extended QL symbols D i and GL unextended symbols, as follows:
  • x i [d i ,s i,L+1 ,s i,L+2 ,...,s i,G ].
  • the following matrix A up shows the uplink steering vector matrix for the serving terminal and the interfering terminal:
  • the jth element of the uplink steering vector representing the i-th user terminal (service terminal or interfering terminal). Since the number of antennas on the small base station side is M ⁇ N, the size of the uplink steering vector matrix A up is (MN) ⁇ K.
  • the extended signal received by the small base station can be expressed as follows:
  • F up is the large-scale fading coefficient of the uplink channel, and F up can be expressed as follows:
  • ⁇ i is the channel large-scale fading coefficient of the uplink transmission of the i-th user terminal.
  • a small base station uses a pilot signal to distinguish signals belonging to different user terminals from the received signals, and estimates the angle of arrival of the signals of the respective user terminals.
  • the signal used to estimate the angle of arrival for a particular user terminal may be represented as the following matrix Y 1 :
  • the angle of arrival of the signal of the user terminal 1 is then estimated by the ESPRIT algorithm using the signal Y 1 .
  • Y 1 (row1:row2,:) represents a new matrix formed by the first row to the second row of the matrix Y 1 .
  • Y 1,1 , Y 1,2 , Y 1,3 are all (M-1) ⁇ L, so we can get the following two matrices R 1 and R 2 :
  • R 1 [Y 1,1 Y 1,2 Y 1,3 ]
  • the dimension of R 1 is (M-1) ⁇ 3L, and the dimension of R 2 is 3(M-1) ⁇ L.
  • Singular value decomposition is performed on R 1 and R 2 respectively, and the results are as follows:
  • U 1 , U 2 , V 1 , and V 2 are ⁇ matrices
  • S 1 and S 2 are diagonal matrices
  • ( ⁇ ) H represents conjugate transpose
  • d is the distance between two adjacent antennas.
  • the pitch angle of the estimate arccos(abs(point)).
  • the angle of arrival of the transmission signal of the specific user terminal (for example, the user terminal 1) is obtained by calculation.
  • the angle of arrival of the user terminal signal is estimated based on the snoop reference signal (SRS) transmitted by the user terminal.
  • SRS snoop reference signal
  • each user terminal in the wireless communication system generates SRS data in the frequency domain according to the indication of the small base station, and spreads the SRS data using the spreading code allocated by the small base station, and then performs inverse Fourier transform (IFFT) Transforms the extended SRS data into a time domain SRS signal and transmits the SRS signal.
  • IFFT inverse Fourier transform
  • the serving terminals served by the same small base station are assigned the same spreading code, and the serving terminals generate SRS data in the frequency domain based on the indication of the small base station, and then generate the same using the assigned same spreading code.
  • the SRS data is extended, inverse Fourier transformed, and transmitted.
  • the generated SRS data has a length of 10 and is a frequency domain signal.
  • the spreading code length is 8
  • the serving terminal served by the same small base station allocates the SRS data to different subcarriers according to the indication of the small base station, so as to be orthogonal to each other in the frequency domain, and then the signal is converted by inverse Fourier transform. Transforms into the time domain and sends the transformed SRS signal.
  • the spreading codes assigned to the user terminals served by different small base stations are orthogonal to each other, which In this way, even if the user terminals served by different small base stations occupy the same frequency band, they can be distinguished according to mutually orthogonal spreading codes, so that the angle of arrival estimation of the signals of all user terminals can be realized.
  • the small base station can receive the extended SRS signal transmitted by each user terminal within its coverage area, and calculate the angle of arrival of each user terminal signal based on the extended signal.
  • the method of calculating the angle of arrival based on the extended SRS can employ the ESPRIT algorithm. Since the ESPRIT algorithm has been described above, it will not be described here.
  • the above describes two methods of estimating the angle of arrival of the user terminal signal based on the spread signal according to the present invention, and the following will describe the use of the estimated angle of arrival of the user terminal signal in the uplink to recover the signal of the serving terminal in the uplink. deal with.
  • the present invention proposes a dual layer MIMO structure, namely, a smart antenna (SA) layer and a MIMO layer.
  • SA smart antenna
  • the smart antenna array on the small base station side includes a sub-array corresponding to each service terminal.
  • a sub-array corresponding to each service terminal by using the corresponding receiving right vector An antenna sub-array corresponding to the i-th serving terminal pairs the aforementioned received signal After processing, the processed signal can be expressed as In this case, the corresponding signal to interference and noise ratio (SINR) can be expressed as follows:
  • E[ ⁇ ] means seeking expectations
  • ⁇ i is the large-scale attenuation coefficient of the uplink channel of the i-th user terminal
  • s i is the signal transmitted by the i-th user terminal
  • the signal power of the i-th user terminal received by the antenna array can be regarded as a constant.
  • ⁇ j is the uplink channel attenuation coefficient of the jth interfering terminal
  • s j is the transmission signal of the jth interfering terminal. Note that the value range of j is (N 1 +1) ⁇ (N 1 + N 2 ).
  • the signal for restoring the i-th serving user terminal is mainly considered while suppressing all the interfering signals and noise received, while the signals of the remaining N 1 -1 serving user terminals need not be suppressed. That is to say, the i-th sub-array contains not only all the information of the i-th service user terminal, but also partial information of the remaining N 1 -1 service user terminals.
  • the optimization objective function for solving the reception weight vector for the i-th sub-array can be established as follows:
  • the above equation represents the modified linear minimum variance constraint (LCMV) criterion proposed by the present invention.
  • the receiving weight vector for the i-th sub-array can be obtained as follows:
  • the transformation matrix of the SA layer can be expressed as follows:
  • the signal received by the small base station can be expressed as follows:
  • N 1 is the number of serving user terminals
  • ⁇ i represents the large-scale attenuation coefficient of the uplink channel of the i-th serving terminal
  • the value of i ranges from 1 to N 1 .
  • the noise in the equivalent MIMO channel is non-white noise after processing by the SA layer. Therefore, the noise in the equivalent MIMO channel should be whitened before the processing of the multi-user signal.
  • the covariance matrix of interference and noise can be expressed as follows:
  • the minimum mean square error algorithm may be used for processing to obtain the signal of the finally recovered service terminal, which is expressed as follows:
  • the above describes the processing of recovering the signal of the serving user terminal by the processing of the two layers of the SA layer and the MIMO layer using the estimated angle of arrival of the user terminal signal in the uplink.
  • the processing of the SA layer and the MIMO layer in the uplink according to the present invention can be more clearly understood with reference to FIG. 6.
  • the angle of arrival of the estimated user terminal signal according to the present invention can also be used to implement beamforming in accordance with conventional LCMV criteria, which will be described below.
  • the small base station calculates for each service user terminal according to the conventional LCMV criterion
  • the beamforming reception weight vector of the serving user terminal Specifically, the small base station calculates a beamforming reception right vector for receiving a signal of the i th service user terminal according to the LCMV criterion shown in the following formula:
  • the calculated beamforming reception weight vector is expressed as follows:
  • the detection process of the signal of the i-th service user terminal can be expressed as follows:
  • r i represents an initial recovery signal of the i-th serving user terminal obtained after processing by the smart antenna layer
  • y 0 represents a signal received by the antenna array
  • ⁇ i represents a channel fading coefficient of the i-th serving user terminal.
  • the technology is applicable to both time division duplex systems and frequency division duplex systems.
  • the following describes the processing of the present technology in the downlink transmission process by taking a frequency division duplex system as an example.
  • the carrier frequencies of the uplink and the downlink are different, and thus the channel characteristics of the uplink and the downlink are not reciprocal.
  • the angle of arrival of the uplink signal and the exit angle of the downlink signal have reciprocity, that is, the direction angles of the upper and lower directions in the frequency division duplex system have reciprocity. Therefore, the beamforming transmission weight vector for downlink transmission can be calculated based on the angle of arrival of the signal estimated in the uplink transmission.
  • the small base station can first generate a downlink steering vector using the estimated uplink signal arrival angle.
  • the downlink steering vector is different from the uplink steering vector because the difference in carrier frequencies results in different wavelengths although the spacing of the antennas remains unchanged during uplink and downlink transmissions.
  • the downlink steering vector can be expressed as follows:
  • ( ⁇ ) T represents the transpose of the matrix
  • the jth element of the downlink steering vector representing the i-th user terminal (serving user terminal or interfering user terminal). and, among them
  • the present invention proposes a modified LCMV criterion to calculate a transmission weight vector for downlink transmission.
  • the modified LCMV criteria can be expressed as follows:
  • a down (N 1 +1: K, :) represents a new one of the matrix A down from the N 1 +1th line to the Kth line
  • x denotes a transmission signal on the antenna
  • ⁇ i DL is a downlink steering vector of the i-th user terminal.
  • the downlink transmission weight vector w i can be calculated as follows:
  • the estimated channel matrix from the small base station to the serving user terminal can be defined as follows:
  • H estimate F down (1:N 1 ,1:N 1 )A down,est (1:N 1 ,:),
  • est is an estimated value of the downlink steering vector A down .
  • the transmission vector can be expressed as among them Is a downlink transmission weight vector corresponding to the i-th serving user terminal.
  • the transfer matrix Z is defined as
  • the estimated channel matrix H estimate can be used to obtain the estimated value Z estimate of the transmission matrix Z, expressed as follows:
  • the precoding matrix for downlink transmission can be expressed as follows:
  • the transmitted signal of the small base station can be expressed as:
  • s represents the data to be sent by the small base station.
  • the above describes the processing of transmitting the signal of the serving user terminal by the processing of the two layers of the SA layer and the MIMO layer using the estimated signal arrival angle of the uplink transmission in the downlink.
  • the processing of the SA layer and the MIMO layer in downlink transmission according to the present invention can be more clearly understood with reference to FIG.
  • Figure 8-10 illustrate a signaling interaction flow in a wireless communication system in accordance with the present invention.
  • Figure 8 illustrates the flow of using the spread signal to estimate the angle of arrival of the signal in the uplink transmission and using the estimated angle of arrival to recover the signal of the serving user terminal.
  • the small base station 1 and the small base station 2 respectively report related information of the serving user terminal in the coverage area to the macro base station.
  • the macro base station instructs each small base station 1, 2 to assign a unique mutually orthogonal spreading code to its serving user terminal based on the reported information, and agrees with the small base station 1, 2 on the length of the spreading code.
  • the small base station 1 and the small base station 2 allocate a spreading code to their serving user terminal, and specify the length of the spreading code.
  • the spreading code to which each user terminal in the wireless communication system is assigned is unique, and the spreading codes of the different user terminals are orthogonal to each other.
  • the serving user terminal of the small base station 1, 2 expands the previous part of the symbol of the data to be transmitted by using the allocated spreading code according to the indication of the small base station, while keeping the latter part of the symbol unchanged, and then transmitting includes extension.
  • the small base station 1, 2 uses the received extended symbols to estimate the angle of arrival of the signal of each user terminal within its coverage area, including the angle of arrival of the serving user terminal signal and the angle of arrival of the interfering user terminal.
  • the small base station 1, 2 calculates an uplink reception weight vector for the serving user terminal based on the corrected LCMV criterion.
  • the small base stations 1, 2 perform beamforming reception on the signals on the antenna using the calculated reception weight vector, and form a virtual MIMO layer.
  • the small base stations 1, 2 perform joint detection on the signals of the respective serving user terminals using a zero-forcing algorithm or a minimum mean square error algorithm.
  • FIG. 9 shows a flow in which an extended SRS is used to estimate an angle of arrival of a signal in an uplink transmission, and the estimated angle of arrival is utilized to recover information of a serving user terminal.
  • the small base station 1 and the small base station 2 respectively report related information of the serving user terminal in the coverage area to the macro base station.
  • the macro base station allocates a spreading code to each small base station based on the reported information.
  • the spreading code assigned by the small base station 1 and the spreading code assigned by the small base station 2 are orthogonal to each other.
  • the small base stations 1, 2 respectively allocate the spreading codes allocated by the macro base station to their serving user terminals.
  • the serving user terminals of the same small base station are assigned the same spreading code, and the serving users of the small base station 1
  • the spreading code assigned by the terminal is orthogonal to the spreading code assigned by the serving user terminal of the small base station 2.
  • the small base station 1, 2 sets SRS uplink configuration information for its serving user terminal.
  • the serving user terminal of the small base station 1, 2 generates the SRS using the configuration information according to the indication of the small base station, and expands and transmits the SRS by using the allocated spreading code.
  • the small base station uses the received extended SRS to estimate the angle of arrival of the signal of each user terminal within its coverage area, including the angle of arrival of the serving user terminal signal and the angle of arrival of the interfering user terminal.
  • the small base station 1, 2 calculates a reception weight vector for the serving user terminal based on the corrected LCMV criteria.
  • SA smart antenna
  • the small base stations 1, 2 perform beamforming reception on the signals on the antenna using the calculated reception weight vector, and form a virtual MIMO layer.
  • the small base stations 1, 2 perform joint detection on the signals of the respective serving user terminals using a zero-forcing algorithm or a minimum mean square error algorithm.
  • a downlink transmission weight vector for a serving user terminal is calculated using an angle of arrival estimated in an uplink transmission, and transmitted using the calculated transmission weight vector for The flow of signals that serve the user terminal.
  • the small base station 1, 2 calculates a steering vector for the serving user terminal and the interfering user terminal based on the estimated signal arrival angle in the uplink transmission process.
  • the small base station 1, 2 transmits a pilot sequence, and the serving user terminal estimates the fading coefficient of the downlink channel, that is, the large-scale fading coefficient based on the received pilot information.
  • the serving user terminal feeds back the estimated fading coefficient to the small base station 1, 2.
  • the small base station 1, 2 calculates a transmission weight vector for the serving user terminal based on the modified LCMV criterion.
  • a virtual MIMO layer is formed according to the calculated transmission weight vector.
  • the small base station 1, 2 performs zero-forcing precoding on the data to be transmitted to the serving user terminal, and then performs pre-weighting (i.e., multiplication by the calculated transmission weight vector).
  • the small base station 1, 2 transmits the pre-weighted signal to the serving user terminal.
  • the method for estimating the angle of arrival of the user terminal signal and the processing in the uplink and downlink are described above by taking the small base station as an example, but the methods and processes may also be performed by the macro base station.
  • the signaling interaction between the small base station and the macro base station may be omitted in the signaling interaction procedure described in connection with FIG. 8 to FIG. 10, but the macro base station directly communicates with the user terminal.
  • the present invention is directed to a multi-cell (small cell) multi-user multi-interference environment for future wireless communication, and proposes a method for estimating the angle of arrival of a user terminal signal based on an extended signal (such as extended data or extended SRS), and proposes a dual layer MIMO.
  • Structure SA layer, MIMO layer
  • modified LCMV algorithm adapted to the dual layer MIMO structure, and the processing in the uplink transmission and downlink transmission and the signaling interaction flow are designed.
  • the present invention proposes a dual layer MIMO architecture for multi-cell interference coordination in the uplink and downlink.
  • the signal of the interfering user terminal is completely suppressed by the processing of the SA layer, and a virtual MIMO layer is formed, and then the information of the serving user terminal is jointly detected at the virtual MIMO layer.
  • the present invention proposes a modified LCMV criterion for a two-layer MIMO structure, which can effectively improve the throughput rate of the system and reduce the bit error rate of the transmission process.
  • the present invention uses data-based extensions to differentiate user terminals, achieving an angle of arrival estimate of signals for serving user terminals and interfering user terminals.
  • the present invention implements an angle of arrival estimation of a signal of a user terminal based on the extended SRS, thereby effectively reducing system overhead.
  • precoding for downlink transmission is performed using the estimated angle of arrival in the uplink transmission.
  • this can effectively reduce the overhead of feedback of the channel state information of the base station to the base station, especially in the case where the antenna of the transmitting end is gradually increased.
  • the signaling interaction strategy in the present invention is controlled by the macro base station, and thus the signaling exchange strategy is simple and easy to implement.
  • the physical layer algorithm in the present invention is based on interference cancellation technology, which is suitable for interference coordination between multiple cells, and can effectively improve the throughput rate of the system.
  • a series of processes performed by each device or component herein may be implemented by software, hardware, or a combination of software and hardware.
  • the program included in the software may be stored in advance in, for example, a storage medium provided inside or outside each device or component.
  • these programs are written to random access memory (RAM) and executed by a processor (eg, a CPU).
  • FIG. 11 is a block diagram showing an example configuration of computer hardware that performs the method or process of the present invention in accordance with a program.
  • a central processing unit (CPU) 1101, a read only memory (ROM) 1102, and a random access memory (RAM) 1103 are connected to each other through a bus 1104.
  • the input/output interface 1105 is further connected to the bus 1104.
  • the input/output interface 1105 is connected to an input unit 1106 formed by a keyboard, a mouse, a microphone, or the like; an output unit 1107 formed of a display, a speaker, or the like; a storage unit 1108 formed of a hard disk, a nonvolatile memory, or the like; A communication unit 1109 formed of a network interface card (such as a local area network (LAN) card, a modem, etc.); and a drive 1110 that drives the removable medium 1111 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory.
  • LAN local area network
  • the CPU 1101 loads the program stored in the storage unit 1108 into the RAM 1103 via the input/output interface 1105 and the bus 1104, and executes the program to execute the series of processes described above.
  • a program to be executed by a computer may be recorded on a removable medium 1111 as a package medium, such as a magnetic disk (including a floppy disk), an optical disk (including a compact disk-read only memory (CD-ROM)), A digital versatile disc (DVD) or the like, a magneto-optical disc, or a semiconductor memory is formed.
  • a program to be executed by a computer can also be provided via a wired or wireless transmission medium such as a local area network, the Internet, or digital satellite broadcasting.
  • the program can be installed in the storage unit 1108 via the input/output interface 1105.
  • the program can be received by the communication unit 1109 via a wired or wireless transmission medium, and the program is installed in the storage unit 1108.
  • the program may be pre-installed in the ROM 1102 or the storage unit 1108.
  • the program to be executed by the computer may be executed in accordance with the order described herein.
  • the program may be a program that executes processing in parallel or performs processing when needed, such as when called.
  • the technology of the present invention can also be configured as follows.
  • a method of performing interference coordination in a communication system comprising a plurality of user terminals, the method comprising: determining, by the user terminal, information from the user terminal The angle of arrival of the transmitted signal; and the user terminal requiring service according to the angle of arrival of the signal of the user terminal.
  • the method further includes receiving an extended signal from at least one user terminal within a coverage area of a base station, wherein the at least one user terminal comprises a serving terminal served by the base station and an interfering terminal served by a neighboring base station; Deriving the despreading result of the extended signal, determining that each of the received extended signals is from the serving terminal or the interfering terminal; and using the received extended signal to determine the The angle of arrival of the signal of each of the at least one user terminal.
  • Each of the serving terminal and the interfering terminal spreads a portion of the data transmitted thereto using a spreading code orthogonal to each other, and transmits the extended signal.
  • a part of the data transmitted by the terminal is the first L symbols of the data transmitted by the terminal. L is greater than or equal to 50.
  • Each of the serving terminal and the interfering terminal spreads a listening reference signal generated by the spreading code using a spreading code, and transmits the extended signal.
  • the serving terminal uses the same spreading code, and the listening reference signals generated by the serving terminal are orthogonal to each other.
  • the spreading code used by the serving terminal and the spreading code used by the interfering terminal are orthogonal to each other.
  • a method for receiving a signal in an uplink at a base station side includes: determining an angle of arrival of a signal of each of the serving terminal and the interfering terminal; An antenna layer initially recovering a signal of the serving terminal based on an angle of arrival of a signal of the serving terminal; and, at the multiple input multiple output MIMO layer, recovering a signal of the serving terminal again based on the initial restored signal.
  • the method further includes determining, based on an angle of arrival of a signal of the serving terminal, a reception right vector of the service terminal, and obtaining an initial restoration signal of the service terminal by using the reception right vector.
  • the method further includes: determining a covariance matrix of the signal and noise transmitted by the interfering terminal; forming an uplink steering vector for the serving terminal by determining an angle of arrival of the signal of the serving terminal; and using The determined covariance matrix and the formed uplink steering vector determine the receive weight vector for the serving terminal.
  • the method further includes: generating an equivalent MIMO channel at the smart antenna layer; and performing noise whitening on the equivalent MIMO channel at the MIMO layer, and whitening the initial restored signal.
  • the method further includes recovering a signal of the serving terminal from the initial recovery signal according to a zero forcing algorithm or a minimum mean square error algorithm.
  • a method for transmitting a signal in a downlink at a base station side includes: determining an angle of arrival of a signal of each of the serving terminal and the interfering terminal; An angle of arrival of a signal of the serving terminal to determine a transmission weight vector for the serving terminal; and transmitting a signal for the serving terminal by using the determined transmission weight vector to transmit The signal of the service terminal.
  • the method further includes determining a covariance matrix of signals transmitted by the base station to the interfering terminal; forming a downlink steering vector for the serving terminal by determining an angle of arrival of a signal of the serving terminal And determining the transmit weight vector for the serving terminal using the determined covariance matrix and the formed downlink steering vector.
  • the method further includes the base station obtaining a precoding matrix based on a channel large-scale fading coefficient fed back from the serving terminal and a transmission weight vector for the serving terminal, wherein the channel large-scale fading coefficient is Deriving that the serving terminal is estimated based on pilots transmitted by the base station; and the base station transmitting signals for the serving terminal by weighting signals for the serving terminal using the precoding matrix.
  • a base station in a communication system includes a plurality of user terminals, the base station includes one or more processors, and the one or more processors are configured to: Determining an angle of arrival of a signal transmitted by the user terminal from information acquired by the user terminal; and selecting a user terminal requiring service according to an angle of arrival of a signal of the user terminal.
  • the one or more processors are further configured to despread an extended signal from at least one user terminal within a coverage area of the base station, wherein the at least one user terminal Comprising a serving terminal served by the base station and an interfering terminal served by a neighboring base station; determining, based on the despreading result, each extended signal from the serving terminal or the interfering terminal; and using the extended signal An angle of arrival of a signal of each of the at least one user terminal is determined.
  • the extended signal is generated by each of the serving terminal and the interfering terminal by expanding a portion of data transmitted by using a spreading code orthogonal to each other.
  • a part of the data transmitted by the terminal is the first L symbols of the data transmitted by the terminal. L is greater than or equal to 50.
  • the extended signal is generated by extending each of the serving terminal and the interfering terminal by using a spreading code to generate a listening reference signal.
  • the serving terminal uses the same spreading code, and the listening reference signals generated by the serving terminal are orthogonal to each other.
  • the spreading code used by the serving terminal and the spreading code used by the interfering terminal are orthogonal to each other.
  • the one or more processors are further configured to: at the smart antenna layer, initially recover a signal of the serving terminal based on an angle of arrival of a signal of the serving terminal; and at a multiple input multiple output MIMO layer, based on The initial recovery signal again restores the signal of the serving terminal.
  • the one or more processors are further configured to: determine a reception right vector for the serving terminal based on an angle of arrival of a signal of the serving terminal, and obtain the service terminal by using the reception right vector Initial recovery signal.
  • the one or more processors are further configured to: determine a covariance matrix of the signal and noise transmitted by the interfering terminal; form an uplink for the serving terminal by determining an angle of arrival of a signal of the serving terminal a link steering vector; and determining the reception weight vector for the serving terminal using the determined covariance matrix and the formed uplink steering vector.
  • the one or more processors are further configured to: generate an equivalent MIMO channel at the smart antenna layer; and perform noise whitening on the equivalent MIMO channel at the MIMO layer, and whiten the initial recovered signal deal with.
  • the one or more processors are further configured to recover the signal of the serving terminal from the initial resume signal according to a zero forcing algorithm or a minimum mean square error algorithm.
  • the one or more processors are further configured to: determine a transmit weight vector for the serving terminal based on the determined angle of arrival of the signal of the serving terminal; and use the determined transmit weight vector pair for the service The signal of the terminal is weighted.
  • the one or more processors are further configured to: determine to be sent by the base station to the a covariance matrix of a signal interfering with the terminal; forming a downlink steering vector for the serving terminal by determining an angle of arrival of the signal of the serving terminal; and using the determined covariance matrix and the formed downlink The path steering vector determines the transmit weight vector for the serving terminal.
  • the one or more processors are further configured to: obtain a precoding matrix based on a channel large-scale fading coefficient from the serving terminal and a transmission weight vector for the serving terminal; and use the precoding matrix pair A signal for the serving terminal is weighted, wherein the channel large-scale fading coefficient is estimated by the serving terminal based on pilots transmitted by the base station.
  • a base station in a communication system includes: a receiving unit, configured to receive an extended signal from at least one terminal in a coverage area of the base station, wherein the at least one terminal includes a serving terminal served by the base station and an interfering terminal served by the neighboring base station; a determining unit, configured to determine, according to the despreading result of the received extended signal, that each of the received extended signals is from the service a terminal or the interference terminal; and an angle of arrival calculation unit for calculating an angle of arrival of each of the at least one terminal using the received extended signal.
  • the extended signal is generated by each of the serving terminal and the interfering terminal by expanding a portion of data transmitted by using a spreading code orthogonal to each other.
  • a part of the data transmitted by the terminal is the first L symbols of the data transmitted by the terminal. L is greater than or equal to 50.
  • the extended signal is generated by extending each of the serving terminal and the interfering terminal by using a spreading code to generate a listening reference signal.
  • the serving terminal uses the same spreading code, and the listening reference signals generated by the serving terminal are orthogonal to each other.
  • the spreading code used by the serving terminal and the spreading code used by the interfering terminal are orthogonal to each other.
  • the base station further includes: a smart antenna layer processing unit, configured to calculate a reception right vector for the serving terminal based on a calculated angle of arrival of a signal of the serving terminal, and obtain the service terminal by using the reception right vector And an MIMO layer processing unit for recovering the signal of the serving terminal again based on the initial recovery signal.
  • a smart antenna layer processing unit configured to calculate a reception right vector for the serving terminal based on a calculated angle of arrival of a signal of the serving terminal, and obtain the service terminal by using the reception right vector
  • an MIMO layer processing unit for recovering the signal of the serving terminal again based on the initial recovery signal.
  • the smart antenna layer processing unit calculates a covariance matrix of the signal and the noise transmitted by the interfering terminal, forms an uplink steering vector for the serving terminal by using the calculated angle of arrival of the serving terminal, and uses the Calculated covariance matrix and the resulting uplink A steering vector is used to calculate the reception weight vector for the serving terminal.
  • the MIMO layer processing unit recovers a signal of the serving terminal from the initial recovery signal according to a zero forcing algorithm or a minimum mean square error algorithm.
  • the base station further includes: a transmission right vector calculation unit, configured to calculate a transmission right vector for the serving terminal based on the calculated angle of arrival of the serving terminal, and a weighting unit for using the calculated transmission right vector pair for The signal of the serving terminal is weighted; and a transmitting unit is configured to transmit the weighted signal to the serving terminal.
  • a transmission right vector calculation unit configured to calculate a transmission right vector for the serving terminal based on the calculated angle of arrival of the serving terminal, and a weighting unit for using the calculated transmission right vector pair for The signal of the serving terminal is weighted
  • a transmitting unit is configured to transmit the weighted signal to the serving terminal.
  • the transmission right vector calculation unit calculates a covariance matrix of a signal transmitted by the base station to the interference terminal, and forms a downlink guide for the service terminal by calculating an angle of arrival of a signal of the service terminal
  • the vector calculates the transmit weight vector for the serving terminal using the calculated covariance matrix and the formed downlink steering vector.
  • the weighting unit obtains a precoding matrix based on a channel large-scale fading coefficient received from the serving terminal and a transmission weight vector for the serving terminal, and uses the precoding matrix pair for the service terminal
  • the signal is weighted, and wherein the channel large scale fading coefficient is estimated by the serving terminal based on pilots transmitted by the base station.

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Abstract

本发明提供了一种在无线通信系统中执行干扰协调的方法和设备。所述无线通信系统包括复数个用户终端，所述方法包括：根据从所述用户终端获取的信息来确定由所述用户终端发送的信号的到达角，以及根据所述用户终端的信号的到达角来选择需要服务的用户终端。

Description

无线通信系统中执行干扰协调的方法和设备 技术领域
本发明涉及一种在无线通信系统中执行干扰协调的方法和设备，更具体地，涉及一种估计用户终端发送信号的到达角，并且使用该到达角来进行干扰协调的方法和设备。
背景技术
为了适应移动数据流量的快速增长，小基站的部署是未来无线通信发展的趋势。小基站能够有助于更高效地管理和使用现有的无线频谱资源。与宏基站相比，小基站的覆盖区域更小，频谱的空间利用率更高，布局也更灵活。未来在每个宏基站的覆盖区域内可能存在很多个由小基站服务的小小区。
随着小基站数量的增加，在特定小基站覆盖区域内将不仅存在着多个服务用户，还可能存在着不是由本小基站服务的多个干扰用户，干扰用户可能是其它小基站服务的用户，也可能是宏基站服务的用户。如果将小基站的覆盖区域内的所有用户分为服务用户集和干扰用户集，那么每个集都可能包含多个用户。干扰用户集是需要抑制其信号的集合，而服务用户集是希望能够保持其信号的集合，并且希望在服务用户集中实现不会相互影响的多用户通信。因此，小基站之间以及小基站与宏基站之间的干扰协调对于整个无线网络的管理有着极其重要的影响。
干扰协调技术主要是通过协调不同基站之间使用不同的通信资源，尽量减小相邻小区之间的干扰。现有的技术主要是从以下三个方面进行考虑：频域、时域和功率控制。从频域角度来说，主要是使相邻小区使用彼此正交的频谱资源，对小区中心和小区边缘的用户分配不同的频率复用集，从而改善小区边缘用户的通信性能，或是在正交调制技术的基础上合理地复用正交的子载波资源。从时域角度来说，主要是进行子帧管理，使得干扰用户在某些子帧内负载受限或是完全不负载，从而保护服务用户在这些子帧内的可靠通信。功率控制技术通过牺牲部分吞吐量性能来提高通信的质量，例如通过减小干扰基站的发射功率，来保证被干扰用户的通信性能。这三方面的技术虽然有助于降低干扰，但在一定程度上牺牲了系统其它方面的性能。
另一方面，智能天线系统致力于空间资源的开发。通过部署天线阵列，可以通过调节各阵元的加权系数来改变阵列的方向图，使波束总是指向用户信号的到达方向DOA(Direction of Arrival)，而零点对准干扰信号，从而实现波束自动跟随用户信号。该技术提高了天线的增益和信噪比，从而能够在相同频域、相同时隙和相同码组的条件下实现用户量的扩展，是一条解决目前频域资源匮乏、提高通信容量的有效途径。常规的到达角估计技术包括子空间类到达角估计算法，典型算法例如MUSIC和ESPRIT。然而，这些算法仅能估计到达天线阵列的所有信号的到达角，而不能得到每个具体用户终端的信号所对应的到达角，因此基站在下行链路传输时不能很好地避免对其他用户终端的干扰。
因此，针对部署有大量小基站的未来无线通信系统，对多小区多用户多干扰环境下的干扰协调和多用户通信提出了要求。
发明内容
根据本发明的一个方面，提供了一种在通信系统中处理干扰协调的方法，所述通信系统包括复数个用户终端，所述方法包括：根据从所述用户终端获取的信息来确定由所述用户终端发送的信号的到达角，以及根据所述用户终端的信号的到达角来选择需要服务的用户终端。
根据本发明的另一方面，提供了一种用于在基站侧在上行链路中接收信号的方法，包括：确定基站覆盖区域内的服务终端和干扰终端中的每一个终端的信号的到达角；在智能天线层，基于所述服务终端的信号的到达角来初始恢复所述服务终端的信号；以及在多输入多输出(MIMO)层，基于所述初始恢复信号再次恢复服务终端的信号。
根据本发明的另一方面，提供了一种用于在基站侧在下行链路中发送信号的方法，包括：确定基站覆盖区域内的服务终端和干扰终端中的每一个终端的信号的到达角；基于确定的服务终端的信号的到达角来确定用于服务终端的发射权矢量；通过使用所确定的发射权矢量对用于服务终端的信号进行加权，来发射用于服务终端的信号。
根据本发明的又一方面，提供了一种通信系统中的基站，所述通信系统包括复数个用户终端，所述基站包括一个或多个处理器，所述一个或多个处理器被配置为：根据从用户终端获取的信息来确定由用户终端发送的信号的到达角，以及根据用户终端的信号的到达角来选择需要服务的用户终端。
所述一个或多个处理器进一步被配置为：在智能天线层，基于服务终端的信号的到达角来初始恢复服务终端的信号；以及在多输入多输出(MIMO)层，基于所述初始恢复信号再次恢复服务终端的信号。
所述一个或多个处理器进一步被配置为：基于确定的服务终端的信号的到达角来确定用于服务终端的发射权矢量；以及使用所确定的发射权矢量对用于服务终端的信号进行加权。
附图说明
可以通过参考下文中结合附图所给出的描述来更好地理解本发明，其中在所有附图中使用了相同或相似的附图标记来表示相同或者相似的部件。附图连同下面的详细说明一起包含在本说明书中并且形成本说明书的一部分，而且用来进一步说明本发明的优选实施例和解释本发明的原理和优点。在附图中：
图1是示出了部署有大量小基站的无线通信系统的示意图；
图2-4示出了在无线通信系统中存在干扰的场景；
图5示意性地示出了用户终端发送的信号的帧结构；
图6示意地示出了在上行链路传输中智能天线层与MIMO层的处理；
图7示意地示出了在下行链路传输中智能天线层与MIMO层的处理；
图8示出了根据本发明一个实施方式的上行链路传输的信令交互流程；
图9示出了根据本发明另一实施方式的上行链路传输的信令交互流程；
图10示出了根据本发明的下行链路传输的信令交互流程；以及
图11是示出了计算机硬件的示例配置的框图。
具体实施方式
空域干扰抑制技术作为一种能够有效对抗干扰，且不牺牲系统性能的技术手段，近几年也被广泛研究用于小区间的干扰协调。这种技术的思想是针对干扰用户与服务用户在空间上的差异来实现抑制干扰的目的，其通常基于多输入多输出(MIMO)技术来实现。在MIMO系统中，空分复用和波束成形是实现多用户通信的两种技术手段，通过联合这两种手段可以实现更好的干扰抑制，降低系统结构的复杂度，这也是近年来研究MIMO系 统的一个趋势。此外，对于在基站侧部署大规模天线也有了一定的研究。在时分双工系统中，在相干时间之内，上、下行链路的信道特性具有互易性，因此基站可以利用上行链路信道信息来估计信道状态，并且利用估计的信道状态来进行用于下行链路传输的预编码。在频分双工系统中，上、下行链路的信道特性不具有互易性，用户终端需要根据基站发送的导频信息来估计下行链路信道状态信息并反馈给基站，基站根据反馈的信道状态信息来进行预编码处理。随着基站侧天线数量的增加，用于估计下行链路信道状态信息的导频开销会线性增加，并且用户终端反馈的信息量也会线性增加。
图1示意性地示出了本发明所适用的无线通信系统，该系统包括宏基站100，位于宏基站100的覆盖区域内的多个小基站210－250以及多个用户终端300。如图所示，用户终端300可以包括由宏基站100服务的用户终端以及由小基站210－250服务的用户终端。此外，用户终端300可以包括各种便携式移动通信终端，诸如移动电话、笔记本电脑等。图中的深色箭头示出了宏基站或每个小基站与其服务的用户终端之间的通信链路，浅色(空心)箭头示出了宏基站或每个小基站与不属于其服务用户终端的其它用户终端之间互为干扰的通信链路。
相比宏基站100数公里的覆盖区域以及较高的发射功率，小基站210－250以较低的发射功率服务于几十米到几百米范围内的用户终端。由于小基站数量众多，相邻小基站之间，以及小基站和宏基站之间的干扰协调管理对于系统的通信性能至关重要。例如，假设当小基站210处于工作状态时，由相邻其他小基站服务的用户终端或是由宏基站服务的用户终端(以下统称为“干扰用户终端”或“干扰终端”)进入小基站210的覆盖区域，则此时小基站210和这些干扰用户终端都会对彼此的通信造成干扰。具体来说，在上行链路中，小基站210将受到这些干扰用户终端的干扰；在下行链路中，这些干扰用户终端将受到小基站210所发送的信号的干扰。
针对图1所示的无线通信系统，本发明提出了通过估计每个用户终端所发送信号的到达角来实现多小区多用户的干扰协调和通信的方法。
图2-4示出了存在干扰的几种场景。图2示出了小基站210与小基站220之间存在干扰的情况。如图2所示，小基站210与小基站220之间存在着重叠的覆盖区域。当小基站210检测到其覆盖区域内的用户状态发生了变化(包括新的服务用户的产生，由于小基站220的服务用户进入自身覆盖区域而产生了干扰)时，小基站210将估计每个用户发送信号的到达角， 并且通过与小基站220之间的信令交互来判断哪些到达角属于服务用户终端，哪些到达角属于干扰用户终端。在估计出所有用户终端发送信号的到达角之后，在这些服务用户终端和干扰用户终端之间进行干扰协调和多用户的通信。
图3示出了小基站210与宏基站100之间存在干扰的情况。如图3所示，小基站210位于宏基站100的覆盖区域内。当小基站210检测到其覆盖区域内用户状态发生了变化(包括新的服务用户的产生，由于宏基站100的服务用户进入自身覆盖区域而产生了干扰)时，小基站210将估计每个用户终端信号的到达角，并且通过与宏基站100之间的信令交互来判断哪些到达角属于服务用户终端，哪些到达角属于干扰用户终端。在估计出所有用户终端信号的到达角之后，在这些服务用户终端和干扰用户终端之间进行干扰协调和多用户的通信。
图4示出了宏基站100与宏基站110之间存在干扰的情况。如图4所示，宏基站100与宏基站110之间存在着重叠的覆盖区域。当宏基站100检测到其覆盖区域内用户状态发生了变化(包括新的服务用户的产生，由于宏基站110的服务用户进入自身覆盖区域而产生了干扰)时，宏基站100将估计每个用户终端信号的到达角，并且通过与宏基站110之间的信令交互来判断哪些到达角属于服务用户终端，哪些到达角属于干扰用户终端。在估计出所有用户终端信号的到达角之后，在这些服务用户终端和干扰用户终端之间进行干扰协调和多用户的通信。
以下以小基站210为例，来描述小基站如何确定其覆盖区域内是否存在干扰用户终端。小基站210可以从宏基站100接收用于指示是否存在由宏基站100或相邻小基站(例如小基站220、250)服务的用户终端的信息。当该信息指示不存在由宏基站100或相邻小基站服务的用户终端时，小基站210确定其覆盖区域内不存在干扰终端。当该信息指示存在着由宏基站100或相邻小基站服务的用户终端时，小基站210确定其覆盖区域内存在干扰终端。
当小基站210确定其覆盖区域内不存在干扰终端时，也就是说，其覆盖区域内只存在服务用户终端，在此情况下，小基站210可直接估计各个服务用户终端的信号的到达角，实现本小小区内多用户的通信。
当小基站210确定其覆盖区域内存在干扰用户终端时，除了估计服务用户终端的信号的到达角之外，小基站210还要估计干扰用户终端的信号的到达角，然后利用所估计的每个用户终端的到达角来实现干扰协调和服务 用户的通信。
根据网络内数据传输方向的不同，将数据传输分为上行链路传输和下行链路传输。上行链路传输的信号称为上行链路信号，下行链路传输的信号称为下行链路信号，以下分别进行描述。
上行链路传输
假设在一小基站的覆盖区域内存在多个用户终端，包括N1个服务终端和N2个干扰终端，并且K＝N1+N2。(本文中，将假设下标1～N1表示服务终端，下标(N1+1)～(N1+N2)表示干扰终端。在此情况下，小基站接收到的上行链路信号y0可表示如下：
Figure PCTCN2016076486-appb-000001
其中，
Figure PCTCN2016076486-appb-000002
表示第i个用户终端(服务终端或者干扰终端)的上行链路导向矢量，其主要由小基站的天线阵列模型、用户终端发送信号的波长和到达角决定。例如，如果天线阵列为M×N矩阵，λup是上行链路信号的波长，并且λup＝c/fup，c是光速，fup是上行链路的载波频率，
Figure PCTCN2016076486-appb-000003
和θi分别是第i个用户终端发送信号的到达方位角和俯仰角，则第i个用户终端的上行链路导向矢量可表示为
Figure PCTCN2016076486-appb-000004
其中(xn,yn)表示第n个阵元位于整个天线阵列中的位置。
此外，上式中的εi表示从第i个用户终端到天线阵列的信道增益。si表示第i个用户终端发送的信号，n表示天线阵列接收到的噪声。
以上给出了小基站所接收到的上行链路信号y0的表示，以下将描述本发明提出的基于扩展信号来估计用户终端信号的到达角的两种方法。
(1)基于数据的到达角估计方法
(a)信号模型
首先，假设小基站覆盖区域内存在K个用户终端，包括N1个服务终端和N2个干扰终端(N1+N2＝K)。如上所述，假设下标1～N1表示服务终端，下标(N1+1)～(N1+N2)表示干扰终端。此外，在小基站侧设置M×N个天线，这 些天线组成平面阵列，每个用户终端具有一个天线。
假设每个用户终端发送的信号的长度为G，那么第i个用户终端发送的信号可以表示为以下等式：
si＝[si,1,si,2,...,si,L,...,si,G]  i＝1,...,K。
根据本实施方式的到达角估计方法使用每个用户终端所要发送的数据中的前L个(例如，L≥50)符号来估计信号的到达角。需要注意的是，L取值过大会增加系统开销，并且当L≥50时，随着L的增大，系统性能的提高很小，故建议在此范围内取较小的值。具体来说，每个用户终端使用一个随机正交码来对要发送的数据中的前L个符号进行扩展，然后发送包括经扩展的前L个符号以及未扩展的G-L个符号的符号序列。图5示意性地示出了用户终端所发送的信号的帧结构。
在此情况下，第i个用户终端的扩展信号可以表示如下：
Figure PCTCN2016076486-appb-000005
其中，
Figure PCTCN2016076486-appb-000006
是第i个用户终端所使用的扩展码，
Figure PCTCN2016076486-appb-000007
代表Kronecker积，Q表示扩展长度(Q≥K)。
第i个用户终端发送的信号可以被表示为包括经扩展的QL个符号di和未扩展的G-L个符号的序列，如下所示：
xi＝[di,si,L+1,si,L+2,...,si,G]。
以下矩阵Aup示出了用于服务终端和干扰终端的上行链路导向矢量矩阵：
Figure PCTCN2016076486-appb-000008
其中
Figure PCTCN2016076486-appb-000009
表示第i个用户终端(服务终端或者干扰终端)的上行链路导向矢量的第j个元素。因为小基站侧天线数目为M×N，所以上行链路导向矢量矩阵Aup的大小为(MN)×K。
在这种情况下，小基站接收到的经扩展的信号可以表示如下：
Figure PCTCN2016076486-appb-000010
其中，NT是噪声分量，Fup是上行链路信道的大尺度衰落系数，并且Fup可表示如下：
Figure PCTCN2016076486-appb-000011
其中εi是第i个用户终端的上行链路传输的信道大尺度衰落系数。
(b)基于信号的到达角估计方法的步骤
①小基站使用导频信号来从接收信号中区分出属于不同用户终端的信号，并且估计各个用户终端的信号的到达角。例如，针对特定用户终端(例如用户终端1)进行到达角估计时使用的信号可表示为以下矩阵Y1：
Figure PCTCN2016076486-appb-000012
Y1的维度是MN×L，因此可以将它进一步表示为如下：
Figure PCTCN2016076486-appb-000013
然后使用信号Y1，通过ESPRIT算法来估计用户终端1的信号的到达角。
以下将描述使用ESPRIT算法来估计信号的到达角的方法。
②在接收信号Y1中构造以下三个子矩阵：
Y1,1＝Y1(1:M-1,:)
Y1,2＝Y1(2:M,:)
Y1,3＝Y1(M+1:2×M-1,:)，
其中，Y1(row1:row2,:)表示矩阵Y1的第row1行到第row2行所构成的新的矩阵。
Y1,1，Y1,2，Y1,3的维度都是(M-1)×L，因此我们可以得到以下两个矩阵R1和R2：
R1＝[Y1,1 Y1,2 Y1,3]
Figure PCTCN2016076486-appb-000014
其中，R1的维度是(M-1)×3L，R2的维度是3(M-1)×L。
对R1和R2分别进行奇异值分解(SVD)，结果如下：
Figure PCTCN2016076486-appb-000015
Figure PCTCN2016076486-appb-000016
其中，U1，U2，V1，V2为酉矩阵，S1，S2为对角矩阵，(□)H表示共轭转置。
令
Figure PCTCN2016076486-appb-000017
其中D表示需要估计的到达角对数，
计算
Figure PCTCN2016076486-appb-000018
以及
Figure PCTCN2016076486-appb-000019
对Eb进行Schur分解，结果如下：
Figure PCTCN2016076486-appb-000020
令
Figure PCTCN2016076486-appb-000021
再一次对F进行Schur分解，结果如下：
Figure PCTCN2016076486-appb-000022
计算TE的对角线相位坐标y和TF的对角线相位坐标x，得到
Figure PCTCN2016076486-appb-000023
Figure PCTCN2016076486-appb-000024
其中d是两相邻天线间的距离。
令变量point＝coordinate(x)+i×coordinate(y)，令angle(point)表示point的相位，令abs(point)表示point的绝对值，那么可以得到用户终端1的信号的到达角估计值如下：
Figure PCTCN2016076486-appb-000025
估计值的俯仰角＝arccos(abs(point))。
由此，通过计算得到了特定用户终端(例如用户终端1)的发送信号的到达角。
(2)基于侦听参考信号的到达角估计方法
在本实施方式中，基于用户终端发送的侦听参考信号(SRS)来估计用户终端信号的到达角。
具体来说，根据本发明的无线通信系统中的每个用户终端根据小基站的指示产生频域上的SRS数据，并使用小基站分配的扩展码对SRS数据进行扩展，然后通过逆傅立叶变换(IFFT)将经扩展的SRS数据变换为时域的SRS信号，并且将此SRS信号进行发送。
一方面，由同一小基站服务的服务终端被分配到相同的扩展码，这些服务终端基于该小基站的指示而产生频域上的SRS数据，然后使用所分配的相同的扩展码对其产生的SRS数据进行扩展、逆傅立叶变换和发送。例如，产生的SRS数据长度为10，并且为频域信号，假设扩展码长度为8，那么经扩展的SRS的数据长度为10×8＝80。在得到经扩展的SRS数据后，同一小基站所服务的服务终端根据小基站的指示将SRS数据分配到不同的子载波上，以使得在频域上相互正交，然后通过逆傅立叶变换将信号变换到时域，并且发送变换后的SRS信号。
另一方面，对不同小基站所服务的用户终端分配的扩展码相互正交，这 样，即使不同小基站所服务的用户终端占据相同的频段，也可以根据相互正交的扩展码而区分它们，从而可以实现所有用户终端的信号的到达角估计。
小基站可以接收到其覆盖区域内的每个用户终端发送的经扩展的SRS信号，并且基于该经扩展的信号来计算每个用户终端信号的到达角。基于经扩展的SRS来计算到达角的方法可采用ESPRIT算法。由于在上文中已经描述了ESPRIT算法，故此处不再赘述。
以上描述了根据本发明的基于经扩展信号来估计用户终端信号的到达角的两种方法，以下将描述在上行链路中小基站使用所估计的用户终端信号的到达角来恢复服务终端的信号的处理。
本发明提出了双层MIMO结构，即，包括智能天线(SA)层和MIMO层。下面首先描述SA层的处理。
小基站侧的智能天线阵列包括对应于每个服务终端的子阵列。以第i个服务终端为例，通过使用与其相对应的接收权矢量
Figure PCTCN2016076486-appb-000026
与该第i个服务终端相对应的天线子阵列对前述接收到的信号
Figure PCTCN2016076486-appb-000027
进行处理,处理后的信号可表示为
Figure PCTCN2016076486-appb-000028
在此情况下，相应的信号与干扰和噪声比(SINR)可表示为如下：
Figure PCTCN2016076486-appb-000029
其中，
Figure PCTCN2016076486-appb-000030
表示接收到的所有服务用户终端信号的协方差矩阵。其中，E[·]表示求期望，
Figure PCTCN2016076486-appb-000031
是第i个用户终端的上行链路导向矢量，εi是第i个用户终端的上行信道大尺度衰减系数，si是第i个用户终端发送的信号，
Figure PCTCN2016076486-appb-000032
表示天线阵列接收到的第i个用户终端的 信号功率，可视为常数。此外，
Figure PCTCN2016076486-appb-000033
表示接收到的所有干扰用户终端信号和噪声的协方差矩阵。其中，
Figure PCTCN2016076486-appb-000034
表示第j个干扰终端的上行链路导向矢量，εj是第j个干扰终端的上行信道衰减系数，sj是第j个干扰终端的发送信号。注意j的取值范围是(N1+1)～(N1+N2)。
对于第i个子阵列，主要考虑用于恢复第i个服务用户终端的信号，同时抑制接收到的所有干扰信号和噪声，而其余N1-1个服务用户终端的信号则不需要被抑制。也就是说，第i个子阵列不仅包含了第i个服务用户终端的所有信息，并且还包含其余N1-1个服务用户终端的部分信息。
可建立求解针对第i个子阵列的接收权矢量的优化目标函数如下：
Figure PCTCN2016076486-appb-000035
通过限制第i个服务用户终端信号方向上的增益满足常数的要求，可将上述优化目标函数变换为如下：
Figure PCTCN2016076486-appb-000036
上式表示了本发明提出的修正的线性最小方差约束(LCMV)准则。
求解上式，可得到针对第i个子阵列的接收权矢量如下：
Figure PCTCN2016076486-appb-000037
考虑所有子阵列，则SA层的转换矩阵可表示如下：
Figure PCTCN2016076486-appb-000038
因此，经过SA层的处理，小基站接收到的信号可表示为如下：
r＝(WUL)Hy0。
下面描述MIMO层的处理。
在MIMO层，所有服务用户终端的信号被联合恢复。在经过如上所述的SA层的处理后，可以得到一个虚拟的N1×N1等效MIMO信道(N1是服务用户终端的数目)。等效信道矩阵可表示为如下：
Figure PCTCN2016076486-appb-000039
其中，
Figure PCTCN2016076486-appb-000040
并且，
Figure PCTCN2016076486-appb-000041
表示第i个服务终端的上行链路导向矢量，εi表示第i个服务终端的上行信道大尺度衰减系数，i的取值范围是1～N1。
同时应该注意，经过SA层的处理，等效MIMO信道中的噪声是非白噪声。因此在进行多用户信号的处理之前，应该先对等效MIMO信道中的噪声进行白化处理。在等效MIMO信道中，干扰和噪声的协方差矩阵可以表示为如下：
Figure PCTCN2016076486-appb-000042
其中
Figure PCTCN2016076486-appb-000043
表示天线阵列接收到的第j个干扰用户终端的信号功率(j的取值范围是(N1+1)～(N1+N2))，σ2表示接收到的噪声方差。
对上述协方差矩阵进行奇异值分解可以得到：
Figure PCTCN2016076486-appb-000044
其中ΛΣ是对角矩阵，并且对角线上的元素都是非负的，U是酉矩阵，那么有：
Figure PCTCN2016076486-appb-000045
对等效MIMO信道进行噪声白化处理，可以得到：
Figure PCTCN2016076486-appb-000046
其中
Figure PCTCN2016076486-appb-000047
对SA层得到的接收信号进行白化处理，可以得到：
Figure PCTCN2016076486-appb-000048
然后采用迫零算法进行处理，可以得到最终恢复出的服务终端的信号，表示如下：
Figure PCTCN2016076486-appb-000049
或者，也可采用最小均方误差算法进行处理，从而得到最终恢复出的服务终端的信号，表示如下：
Figure PCTCN2016076486-appb-000050
以上描述了在上行链路中小基站使用所估计的用户终端信号的到达角，通过SA层和MIMO层两层的处理来恢复服务用户终端的信号的处理。结合参考图6，可以更清楚地理解根据本发明在上行链路中SA层和MIMO层的处理。
除此以外，根据本发明所估计的用户终端信号的到达角还可用于按照常规的LCMV准则来实现波束成形，以下将描述这一处理。
小基站针对每个服务用户终端，根据常规的LCMV准则来计算对于该 服务用户终端的波束成形接收权矢量。具体来说，小基站根据如下式所示的LCMV准则来计算用于接收第i个服务用户终端的信号的波束成形接收权矢量：
Figure PCTCN2016076486-appb-000051
其中，
Figure PCTCN2016076486-appb-000052
计算得到的波束成形接收权矢量表示如下：
Figure PCTCN2016076486-appb-000053
从而，第i个服务用户终端的信号的检测过程可以表示为如下：
Figure PCTCN2016076486-appb-000054
其中，ri表示经智能天线层的处理后得到的第i个服务用户终端的初始恢复信号，y0表示天线阵列接收到的信号，εi表示第i个服务用户终端的信道衰落系数。
下行链路传输
本技术既适用于时分双工系统，也适用于频分双工系统。下面以频分双工系统为例对本技术在下行链路传输过程中的处理进行描述。
在频分双工系统中，上行链路和下行链路的载波频率不同，因此上行链路和下行链路的信道特性不具有互易性。然而，上行链路信号的到达角和下行链路信号的离开角具有互易性，也就是说，在频分双工系统中上、下行的方向角具有互易性。因此，可以基于在上行链路传输中估计的信号的到达角来计算用于下行链路传输的波束成形发射权矢量。
如上所述，因为上行链路信号的到达角和下行链路信号的离开角具有互 易性，因此在下行链路传输中，小基站可以使用估计的上行链路信号到达角来首先生成下行链路导向矢量。该下行链路导向矢量不同于上行链路导向矢量，这是因为虽然上、下行链路传输时天线的间距保持不变，但是载波频率的不同导致了波长的不同。
当存在N1个服务用户终端和N2个干扰用户终端时(N1+N2＝K，假设下标1-N1表示N1个服务用户终端，下标N1+1-K表示N2个干扰用户终端)，下行链路导向矢量可被表示如下：
Figure PCTCN2016076486-appb-000055
其中，(·)T表示矩阵的转置，
Figure PCTCN2016076486-appb-000056
表示第i个用户终端(服务用户终端或干扰用户终端)的下行链路导向矢量的第j个元素。并且，
Figure PCTCN2016076486-appb-000057
其中
Figure PCTCN2016076486-appb-000058
和θi分别是指向第i个用户终端的方位角和俯仰角，(xn,yn)表示第n个阵元位于整个天线阵列中的位置，λdown表示下行链路传输的波长，并且λdown＝c/fdown，其中c是光速，fdown是下行链路传输频率。
因为小基站在进行下行链路传输时会影响其覆盖区域内的干扰用户终端的上行链路传输，因此需要考虑在使服务用户终端的增益最大化的同时，减小小基站的下行链路传输对于干扰用户终端的通信的干扰。基于这种考虑，本发明提出了修正的LCMV准则来计算用于下行链路传输的发射权矢量。此时，该修正的LCMV准则可以表示如下：
Figure PCTCN2016076486-appb-000059
其中，
Figure PCTCN2016076486-appb-000060
是下行链路发射权矢量，
Figure PCTCN2016076486-appb-000061
表示在下行链路上发送至所有干扰用户终端的信号的协方差矩阵，Adown(N1+1:K,:)表示矩阵Adown第N1+1行到第K行所构成的新的矩阵，其是对应于干扰用户终端的下行链路导向矢量，x表示天线上的发射信号，αi DL是 第i个用户终端的下行链路导向矢量。
根据以上准则，可计算得到下行链路发射权矢量wi如下：
Figure PCTCN2016076486-appb-000062
从小基站到服务用户终端的信道矩阵可以表示为H＝Fdown(1:N1,1:N1)Adown(1:N1,:)，其中Adown(1:N1,:)表示矩阵Adown第1行到第N1行所构成的新的矩阵，Fdown(1:N1,1:N1)表示矩阵Fdown第1行到第N1行以及第1列到第N1列内所有元素所构成的新的矩阵，Fdown表示下行链路信道大尺度衰落系数且为对角阵，Fdown可表示如下：
Figure PCTCN2016076486-appb-000063
其中，
Figure PCTCN2016076486-appb-000064
是针对第i个用户终端(服务终端或干扰终端)的下行链路传输的信道大尺度衰落系数。
基于此，估计的从小基站到服务用户终端的信道矩阵可定义为如下：
Hestimate＝Fdown(1:N1,1:N1)Adown,est(1:N1,:)，
其中，Adown,est是下行链路导向矢量Adown的估计值。
传输矢量可表示为
Figure PCTCN2016076486-appb-000065
其中
Figure PCTCN2016076486-appb-000066
是对应于第i个服务用户终端的下行链路发射权矢量。基于此，在将传输矩阵Z定义为
Figure PCTCN2016076486-appb-000067
的情况下，可以使用估计的信道矩阵Hestimate来得到传输矩阵Z的估计值Zestimate，表示如下：
Figure PCTCN2016076486-appb-000068
其中,
Figure PCTCN2016076486-appb-000069
是根据修正的LCMV准则得到的对应于第i个服务用户终端的下行链路发射权矢量。
当采用迫零均衡时，用于下行链路传输的预编码矩阵可以表示为如下：
Figure PCTCN2016076486-appb-000070
因此，小基站的发送信号可以表示为：
x＝Ps，
其中s表示小基站要发送的数据。
以上描述了在下行链路中小基站使用所估计的上行链路传输的信号到达角，通过SA层和MIMO层两层的处理来发射服务用户终端的信号的处理。结合参考图7，可以更清楚地理解根据本发明在下行链路传输中SA层和MIMO层的处理。
图8-图10示出了根据本发明的无线通信系统中的信令交互流程。图8示出了在上行链路传输中，使用经扩展的信号来估计信号的到达角，并利用所估计的到达角来恢复服务用户终端的信号的流程。
如图8所示，在S801处，小基站1和小基站2分别将自己覆盖区域内的服务用户终端的相关信息报告给宏基站。
在S802处，宏基站根据所报告的信息，指示每个小基站1,2为其服务用户终端分配唯一的相互正交的扩展码，并且与小基站1,2约定扩展码的长度。
在S803处，根据宏基站的指示，小基站1和小基站2为其服务用户终端分配扩展码，并指定扩展码的长度。此时，无线通信系统中的每个用户终端被分配到的扩展码是唯一的，并且不同用户终端的扩展码相互正交。
在S804处，小基站1,2的服务用户终端根据小基站的指示，利用所分配的扩展码对要发送的数据的前面一部分符号进行扩展，同时保持后面一部分符号不变，然后发送包括经扩展的符号与未扩展的符号的符号序列。
在S805处，小基站1,2使用接收到的经扩展的符号来估计其覆盖区域内的每个用户终端的信号的到达角，包括服务用户终端信号的到达角和干扰用户终端的到达角。
在S806处，小基站1,2基于修正的LCMV准则，计算用于服务用户终端的上行链路接收权矢量。在智能天线(SA)层，小基站1,2利用计算的接收权矢量对天线上的信号进行波束成形接收，并且形成虚拟MIMO层。
在S807处，在虚拟MIMO层，小基站1,2使用迫零算法或者最小均方误差算法，对各自的服务用户终端的信号进行联合检测。
图9示出了在上行链路传输中，使用经扩展的SRS来估计信号的到达角，并利用所估计的到达角来恢复服务用户终端的信息的流程。
如图9所示，在S901处，小基站1和小基站2分别将自己覆盖区域内的服务用户终端的相关信息报告给宏基站。
在S902处，宏基站根据所报告的信息，为每个小基站分配一个扩展码。这里，小基站1所分配到的扩展码与小基站2所分配到的扩展码相互正交。
在S903处，小基站1,2分别将宏基站所分配的扩展码分配给其服务用户终端，此时，同一小基站的服务用户终端被分配到相同的扩展码，并且小基站1的服务用户终端所分配到的扩展码与小基站2的服务用户终端所分配到的扩展码相互正交。此外，小基站1,2为其服务用户终端设置SRS上行链路配置信息。
在S904处，小基站1,2的服务用户终端根据小基站的指示，利用该配置信息产生SRS,并且利用所分配的扩展码对SRS进行扩展并发送。
在S905处，小基站使用接收到的经扩展的SRS来估计其覆盖区域内的每个用户终端的信号的到达角，包括服务用户终端信号的到达角和干扰用户终端的到达角。
在S906处，小基站1,2基于修正的LCMV准则，计算用于服务用户终端的接收权矢量。在智能天线(SA)层，小基站1,2利用计算的接收权矢量对天线上的信号进行波束成形接收，并且形成虚拟MIMO层。
在S907处，在虚拟MIMO层，小基站1,2使用迫零算法或者最小均方误差算法，对各自的服务用户终端的信号进行联合检测。
图10示出了在下行链路传输中，使用在上行链路传输中估计的到达角来计算用于服务用户终端的下行链路发射权矢量，并利用所计算的发射权矢量来发送用于服务用户终端的信号的流程。
如图10所示，在S1001处，小基站1,2根据上行链路传输过程中所估计的信号到达角，来计算对于服务用户终端和干扰用户终端的导向矢量。
在S1002处，小基站1,2发送导频序列，服务用户终端基于接收到的导频信息来估计下行链路信道的衰落系数，即大尺度衰落系数。
在S1003处，服务用户终端将估计的衰落系数反馈给小基站1,2。
在S1004处，小基站1,2根据修正的LCMV准则，计算用于服务用户终端的发射权矢量。
在S1005处，根据计算的发射权矢量，形成了虚拟MIMO层。从而小基站1,2对要发送至服务用户终端的数据先进行迫零预编码，然后进行预加权(即，乘以所计算的发射权矢量)。
在S1006处，小基站1,2将预加权后的信号发送至服务用户终端。
需要说明的是，以上以小基站为例描述了估计用户终端信号的到达角的方法以及在上、下行链路中的处理，但这些方法和处理也可以由宏基站来执行。当由宏基站执行时，结合图8-图10所描述的信令交互流程中可省去小基站与宏基站之间的信令交互，而是由宏基站与用户终端直接进行通信。这种修改对于本领域技术人员将是容易且显而易见的。
本发明针对未来无线通信的多小区(小小区)多用户多干扰环境，提出了基于扩展信号(如扩展的数据或扩展的SRS)来估计用户终端信号的到达角的方法，提出了双层MIMO结构(SA层，MIMO层)以及适应于双层MIMO结构的修正的LCMV算法，并且设计了在上行链路传输与下行链路传输中的处理以及信令交互流程。
本发明的技术具有如下优点：
a.本发明提出了在上行、下行链路中用于多小区干扰协调的双层MIMO结构。首先通过SA层的处理将干扰用户终端的信号完全抑制，并且形成虚拟的MIMO层，然后在虚拟的MIMO层对服务用户终端的信息进行联合检测。
b.本发明针对双层MIMO结构，提出了修正的LCMV准则，可以有效提高系统的吞吐率，降低传输过程的误码率。
c.在上行链路传输中，本发明使用基于数据的扩展来区分用户终端，实现服务用户终端和干扰用户终端的信号的到达角估计。在另一实施方式中，本发明基于扩展的SRS来实现用户终端的信号的到达角估计，从而能够有效地减少系统的开销。
d.在下行链路传输中，利用上行链路传输中估计的到达角来进行用于下行链路传输的预编码。在频分双工系统中，这能够有效减少用户终端对基站的信道状态信息反馈的开销，尤其是在发射端天线逐渐增加的情况下。
e.本发明中的信令交互策略受到宏基站的控制，因此这种信令交换策略简单易于实现。
f.本发明中物理层算法是基于干扰消除技术，其适用于多小区之间的干扰协调，能够有效提高系统的吞吐率。
本文中所描述的各个设备或组件仅是逻辑意义上的，并不严格对应于 物理设备或组件。例如，本文所描述的每个组件的功能可能由多个物理实体来实现，或者，本文所描述的多个组件的功能可能由单个物理实体来实现。
在本文中由每个设备或组件执行的一系列处理可以由软件、硬件或者软件和硬件的组合来实现。包括在软件中的程序可以事先存储在例如每个设备或组件的内部或外部所设置的存储介质中。作为一个示例，在执行期间，这些程序被写入随机存取存储器(RAM)并且由处理器(例如CPU)来执行。
图11是示出了根据程序执行本发明的方法或处理的计算机硬件的示例配置框图。
在计算机中，中央处理单元(CPU)1101、只读存储器(ROM)1102以及随机存取存储器(RAM)1103通过总线1104彼此连接。
输入/输出接口1105进一步与总线1104连接。输入/输出接口1105连接有以下组件：以键盘、鼠标、麦克风等形成的输入单元1106；以显示器、扬声器等形成的输出单元1107；以硬盘、非易失性存储器等形成的存储单元1108；以网络接口卡(诸如局域网(LAN)卡、调制解调器等)形成的通信单元1109；以及驱动移动介质1111的驱动器1110，该移动介质1111诸如是磁盘、光盘、磁光盘或半导体存储器。
在具有上述结构的计算机中，CPU 1101将存储在存储单元1108中的程序经由输入/输出接口1105和总线1104加载到RAM 1103中，并且执行该程序，以便执行上述系列处理。
要由计算机(CPU 1101)执行的程序可以被记录在作为封装介质的移动介质1111上，该封装介质以例如磁盘(包括软盘)、光盘(包括压缩光盘-只读存储器(CD-ROM))、数字多功能光盘(DVD)等)、磁光盘、或半导体存储器来形成。此外，要由计算机(CPU 1101)执行的程序也可以经由诸如局域网、因特网、或数字卫星广播的有线或无线传输介质来提供。
当移动介质1111安装在驱动器1110中时，可以将程序经由输入/输出接口1105安装在存储单元1108中。另外，可以经由有线或无线传输介质由通信单元1109来接收程序，并且将程序安装在存储单元1108中。可替选地，可以将程序预先安装在ROM 1102或存储单元1108中。
要由计算机执行的程序可以是根据本文中描述的顺序来执行处理的 程序，或者可以是并行地执行处理或当需要时(诸如，当调用时)执行处理的程序。
以上已经结合附图详细描述了本发明的实施例以及技术效果，但是本发明的范围不限于此。本领域普通技术人员应该理解的是，取决于设计要求和其他因素，在不偏离本发明的原理和精神的情况下，可以对本文中所讨论的实施方式进行各种修改或变化。本发明的范围由所附权利要求或其等同方案来限定。
本发明的技术还可以配置如下。
根据本发明的一个方面，一种在通信系统中执行干扰协调的方法，所述通信系统包括复数个用户终端，所述方法包括：根据从所述用户终端获取的信息来确定由所述用户终端发送的信号的到达角；以及根据所述用户终端的信号的到达角来选择需要服务的用户终端。
所述方法进一步包括：接收来自基站覆盖区域内至少一个用户终端的经扩展的信号，其中所述至少一个用户终端包括由所述基站服务的服务终端和由相邻基站服务的干扰终端；根据对接收到的所述经扩展的信号的解扩结果，确定接收到的每个经扩展的信号来自所述服务终端或所述干扰终端；以及使用接收到的所述经扩展的信号来确定所述至少一个用户终端中的每个用户终端的信号的到达角。
所述服务终端和所述干扰终端中的每一个终端使用彼此正交的扩展码对其发送的数据的一部分进行扩展，并且发送经扩展的信号。所述终端发送的数据的一部分是所述终端发送的数据的前L个符号。L大于或等于50。
所述服务终端和所述干扰终端中的每一个终端使用扩展码对其产生的侦听参考信号进行扩展，并且发送经扩展的信号。所述服务终端使用相同的扩展码，并且所述服务终端产生的侦听参考信号彼此正交。所述服务终端使用的扩展码与所述干扰终端使用的扩展码彼此正交。
根据本发明的另一个方面，一种用于在基站侧在上行链路中接收信号的方法，包括：确定所述服务终端和所述干扰终端中的每一个终端的信号的到达角；在智能天线层，基于所述服务终端的信号的到达角来初始恢复所述服务终端的信号；以及在多输入多输出MIMO层，基于所述初始恢复信号再次恢复所述服务终端的信号。
所述方法进一步包括：基于所述服务终端的信号的到达角来确定用于 所述服务终端的接收权矢量，以及通过使用所述接收权矢量获得所述服务终端的初始恢复信号。
所述方法进一步包括：确定所述干扰终端发送的信号和噪声的协方差矩阵；通过确定的所述服务终端的信号的到达角来形成用于所述服务终端的上行链路导向矢量；以及使用所确定的协方差矩阵以及所形成的上行链路导向矢量来确定用于所述服务终端的所述接收权矢量。
所述方法进一步包括：在智能天线层，生成等效MIMO信道；以及在MIMO层，对等效MIMO信道进行噪声白化处理，并且对所述初始恢复信号进行白化处理。
所述方法进一步包括：根据迫零算法或最小均方误差算法从所述初始恢复信号来恢复所述服务终端的信号。
根据本发明的另一个方面，一种用于在基站侧在下行链路中发送信号的方法，包括：确定所述服务终端和所述干扰终端中的每一个终端的信号的到达角；基于确定的所述服务终端的信号的到达角来确定用于所述服务终端的发射权矢量；以及通过使用所确定的发射权矢量对用于所述服务终端的信号进行加权，来发射用于所述服务终端的信号。
所述方法进一步包括：确定由所述基站发送至所述干扰终端的信号的协方差矩阵；通过确定的所述服务终端的信号的到达角来形成用于所述服务终端的下行链路导向矢量；以及使用所确定的协方差矩阵以及所形成的下行链路导向矢量来确定用于所述服务终端的所述发射权矢量。
所述方法进一步包括：所述基站基于从所述服务终端反馈的信道大尺度衰落系数以及用于所述服务终端的发射权矢量来获得预编码矩阵，其中，所述信道大尺度衰落系数是所述服务终端基于所述基站发送的导频而估计的；以及所述基站通过使用所述预编码矩阵对用于所述服务终端的信号进行加权，来发射用于所述服务终端的信号。
根据本发明的又一个方面，一种通信系统中的基站，所述通信系统包括复数个用户终端，所述基站包括一个或多个处理器，所述一个或多个处理器被配置为：根据从所述用户终端获取的信息来确定由所述用户终端发送的信号的到达角；以及根据所述用户终端的信号的到达角来选择需要服务的用户终端。
所述一个或多个处理器进一步被配置为：对来自所述基站覆盖区域内至少一个用户终端的经扩展的信号进行解扩，其中所述至少一个用户终端 包括由所述基站服务的服务终端和由相邻基站服务的干扰终端；根据解扩结果，确定每个经扩展的信号来自所述服务终端或所述干扰终端；以及使用所述经扩展的信号来确定所述至少一个用户终端中的每个用户终端的信号的到达角。
所述经扩展后的信号是由所述服务终端和所述干扰终端中的每一个终端通过使用彼此正交的扩展码对其发送的数据的一部分进行扩展而生成。所述终端发送的数据的一部分是所述终端发送的数据的前L个符号。L大于或等于50。
所述经扩展后的信号是由所述服务终端和所述干扰终端中的每一个终端通过使用扩展码对其产生的侦听参考信号进行扩展而生成。所述服务终端使用相同的扩展码，并且所述服务终端产生的侦听参考信号彼此正交。所述服务终端使用的扩展码与所述干扰终端使用的扩展码彼此正交。
所述一个或多个处理器进一步被配置为：在智能天线层，基于所述服务终端的信号的到达角来初始恢复所述服务终端的信号；以及在多输入多输出MIMO层，基于所述初始恢复信号再次恢复所述服务终端的信号。
所述一个或多个处理器进一步被配置为：基于所述服务终端的信号的到达角来确定用于所述服务终端的接收权矢量，以及通过使用所述接收权矢量获得所述服务终端的初始恢复信号。
所述一个或多个处理器进一步被配置为：确定所述干扰终端发送的信号和噪声的协方差矩阵；通过确定的所述服务终端的信号的到达角来形成用于所述服务终端的上行链路导向矢量；以及使用所确定的协方差矩阵以及所形成的上行链路导向矢量来确定用于所述服务终端的所述接收权矢量。
所述一个或多个处理器进一步被配置为：在智能天线层，生成等效MIMO信道；以及在MIMO层，对所述等效MIMO信道进行噪声白化处理，并且对所述初始恢复信号进行白化处理。
所述一个或多个处理器进一步被配置为：根据迫零算法或最小均方误差算法从所述初始恢复信号来恢复所述服务终端的信号。
所述一个或多个处理器进一步被配置为：基于确定的服务终端的信号的到达角来确定用于所述服务终端的发射权矢量；以及使用所确定的发射权矢量对用于所述服务终端的信号进行加权。
所述一个或多个处理器进一步被配置为：确定由所述基站发送至所述 干扰终端的信号的协方差矩阵；通过确定的所述服务终端的信号的到达角来形成用于所述服务终端的下行链路导向矢量；以及使用所确定的协方差矩阵以及所形成的下行链路导向矢量来确定用于所述服务终端的所述发射权矢量。
所述一个或多个处理器进一步被配置为：基于来自所述服务终端的信道大尺度衰落系数以及用于所述服务终端的发射权矢量来获得预编码矩阵；以及使用所述预编码矩阵对用于所述服务终端的信号进行加权，其中，所述信道大尺度衰落系数是由所述服务终端基于所述基站发送的导频而估计的。
根据本发明的又一个方面，一种通信系统中的基站，包括：接收单元，用于接收来自所述基站覆盖区域内至少一个终端的经扩展的信号，其中所述至少一个终端包括由所述基站服务的服务终端和由相邻基站服务的干扰终端；确定单元，用于根据对接收到的所述经扩展的信号的解扩结果，确定接收到的每个经扩展的信号来自所述服务终端或所述干扰终端；以及到达角计算单元，用于使用接收到的所述经扩展的信号来计算所述至少一个终端中的每个终端的到达角。
所述经扩展后的信号是由所述服务终端和所述干扰终端中的每一个终端通过使用彼此正交的扩展码对其发送的数据的一部分进行扩展而生成。所述终端发送的数据的一部分是所述终端发送的数据的前L个符号。L大于或等于50。
所述经扩展后的信号是由所述服务终端和所述干扰终端中的每一个终端通过使用扩展码对其产生的侦听参考信号进行扩展而生成。所述服务终端使用相同的扩展码，并且所述服务终端产生的侦听参考信号彼此正交。所述服务终端使用的扩展码与所述干扰终端使用的扩展码彼此正交。
所述基站还包括：智能天线层处理单元，用于基于计算的服务终端的信号的到达角来计算用于所述服务终端的接收权矢量，并且通过使用所述接收权矢量获得所述服务终端的初始恢复信号；以及多输入多输出MIMO层处理单元，用于基于所述初始恢复信号再次恢复所述服务终端的信号。
所述智能天线层处理单元计算所述干扰终端发送的信号和噪声的协方差矩阵，通过计算的所述服务终端的到达角来形成用于所述服务终端的上行链路导向矢量，并且使用所计算的协方差矩阵以及所形成的上行链路 导向矢量来计算用于所述服务终端的所述接收权矢量。
所述MIMO层处理单元根据迫零算法或最小均方误差算法从所述初始恢复信号来恢复所述服务终端的信号。
所述基站还包括：发射权矢量计算单元，用于基于计算的服务终端的到达角来计算用于所述服务终端的发射权矢量，加权单元，用于使用所计算的发射权矢量对用于所述服务终端的信号进行加权；以及发射单元，用于将经加权的信号发射至所述服务终端。
所述发射权矢量计算单元计算由所述基站发送至所述干扰终端的信号的协方差矩阵，通过计算的所述服务终端的信号的到达角来形成用于所述服务终端的下行链路导向矢量，使用所计算的协方差矩阵以及所形成的下行链路导向矢量来计算用于所述服务终端的所述发射权矢量。
所述加权单元基于从所述服务终端接收到的信道大尺度衰落系数以及用于所述服务终端的发射权矢量来获得预编码矩阵，并且使用所述预编码矩阵对用于所述服务终端的信号进行加权，以及其中，所述信道大尺度衰落系数是由所述服务终端基于所述基站发送的导频而估计的。

Claims (32)

  1. 一种在通信系统中处理干扰协调的方法，所述通信系统包括复数个用户终端，所述方法包括：
    根据从所述用户终端获取的信息来确定由所述用户终端发送的信号的到达角；以及
    根据所述用户终端的信号的到达角来选择需要服务的用户终端。
  2. 根据权利要求1所述的方法，其中，根据从所述用户终端获取的信息来确定由所述用户终端发送的信号的到达角进一步包括：
    接收来自基站覆盖区域内至少一个用户终端的经扩展的信号，其中所述至少一个用户终端包括由所述基站服务的服务终端和由相邻基站服务的干扰终端；
    根据对接收到的所述经扩展的信号的解扩结果，确定接收到的每个经扩展的信号来自所述服务终端或所述干扰终端；以及
    使用接收到的所述经扩展的信号来确定所述至少一个用户终端中的每个用户终端的信号的到达角。
  3. 根据权利要求2所述的方法，其中，所述服务终端和所述干扰终端中的每一个终端使用彼此正交的扩展码对其要发送的数据的一部分进行扩展，并且发送经扩展的信号。
  4. 根据权利要求3所述的方法，其中，所述终端要发送的数据的一部分是所述终端要发送的数据的前L个符号。
  5. 根据权利要求4所述的方法，其中，L大于或等于50。
  6. 根据权利要求2所述的方法，其中，所述服务终端和所述干扰终 端中的每一个终端使用扩展码对其产生的侦听参考信号进行扩展，并且发送经扩展的信号。
  7. 根据权利要求6所述的方法，其中，所述服务终端使用相同的扩展码，并且所述服务终端产生的侦听参考信号彼此正交。
  8. 根据权利要求7所述的方法，其中，所述服务终端使用的扩展码与所述干扰终端使用的扩展码彼此正交。
  9. 一种用于在基站侧在上行链路中接收信号的方法，包括：
    根据权利要求2-8中任一项所述的方法来确定所述服务终端和所述干扰终端中的每一个终端的信号的到达角；
    在智能天线层，基于所述服务终端的信号的到达角来初始恢复所述服务终端的信号；以及
    在多输入多输出MIMO层，基于所述初始恢复信号再次恢复所述服务终端的信号。
  10. 根据权利要求9所述的方法，其中，基于所述服务终端的信号的到达角来初始恢复所述服务终端的信号包括：
    基于所述服务终端的信号的到达角来确定用于所述服务终端的接收权矢量，以及通过使用所述接收权矢量获得所述服务终端的初始恢复信号。
  11. 根据权利要求10所述的方法，其中，基于所述服务终端的信号的到达角来确定用于所述服务终端的接收权矢量包括：
    确定所述干扰终端发送的信号和噪声的协方差矩阵；
    通过确定的所述服务终端的信号的到达角来形成用于所述服务终端的上行链路导向矢量；以及
    使用所确定的协方差矩阵以及所形成的上行链路导向矢量来确定用 于所述服务终端的所述接收权矢量。
  12. 根据权利要求9所述的方法，还包括：
    在智能天线层，生成等效MIMO信道；以及
    在MIMO层，对等效MIMO信道进行噪声白化处理，并且对所述初始恢复信号进行白化处理。
  13. 根据权利要求9所述的方法，其中，基于所述初始恢复信号再次恢复所述服务终端的信号包括：根据迫零算法或最小均方误差算法从所述初始恢复信号来恢复所述服务终端的信号。
  14. 一种用于在基站侧在下行链路中发送信号的方法，包括：
    根据权利要求2-8中任一项所述的方法来确定所述服务终端和所述干扰终端中的每一个终端的信号的到达角；
    基于确定的所述服务终端的信号的到达角来确定用于所述服务终端的发射权矢量；以及
    通过使用所确定的发射权矢量对用于所述服务终端的信号进行加权，来发射用于所述服务终端的信号。
  15. 根据权利要求14所述的方法，其中，基于确定的所述服务终端的信号的到达角来确定用于所述服务终端的发射权矢量包括：
    确定由所述基站发送至所述干扰终端的信号的协方差矩阵；
    通过确定的所述服务终端的信号的到达角来形成用于所述服务终端的下行链路导向矢量；以及
    使用所确定的协方差矩阵以及所形成的下行链路导向矢量来确定用于所述服务终端的所述发射权矢量。
  16. 根据权利要求14所述的方法，通过使用所确定的发射权矢量对用于所述服务终端的信号进行加权来发射用于所述服务终端的信号包 括：
    所述基站基于从所述服务终端反馈的信道大尺度衰落系数以及用于所述服务终端的发射权矢量来获得预编码矩阵，其中，所述信道大尺度衰落系数是所述服务终端基于所述基站发送的导频而估计的；以及
    所述基站通过使用所述预编码矩阵对用于所述服务终端的信号进行加权，来发射用于所述服务终端的信号。
  17. 一种通信系统中的基站，所述通信系统包括复数个用户终端，所述基站包括一个或多个处理器，所述一个或多个处理器被配置为：
    根据从所述用户终端获取的信息来确定由所述用户终端发送的信号的到达角；以及
    根据所述用户终端的信号的到达角来选择需要服务的用户终端。
  18. 根据权利要求17所述的基站，其中，所述一个或多个处理器进一步被配置为：
    对来自所述基站覆盖区域内至少一个用户终端的经扩展的信号进行解扩，其中所述至少一个用户终端包括由所述基站服务的服务终端和由相邻基站服务的干扰终端；
    根据解扩结果，确定每个经扩展的信号来自所述服务终端或所述干扰终端；以及
    使用所述经扩展的信号来确定所述至少一个用户终端中的每个用户终端的信号的到达角。
  19. 根据权利要求18所述的基站，其中，所述经扩展后的信号是由所述服务终端和所述干扰终端中的每一个终端通过使用彼此正交的扩展码对其要发送的数据的一部分进行扩展而生成。
  20. 根据权利要求19所述的基站，其中，所述终端要发送的数据的一部分是所述终端要发送的数据的前L个符号。
  21. 根据权利要求20所述的基站，其中，L大于或等于50。
  22. 根据权利要求18所述的基站，其中，所述经扩展后的信号是由所述服务终端和所述干扰终端中的每一个终端通过使用扩展码对其产生的侦听参考信号进行扩展而生成。
  23. 根据权利要求22所述的基站，其中，所述服务终端使用相同的扩展码，并且所述服务终端产生的侦听参考信号彼此正交。
  24. 根据权利要求23所述的基站，其中，所述服务终端使用的扩展码与所述干扰终端使用的扩展码彼此正交。
  25. 根据权利要求18-24中任一项所述的基站，所述一个或多个处理器进一步被配置为：
    在智能天线层，基于所述服务终端的信号的到达角来初始恢复所述服务终端的信号；以及
    在多输入多输出MIMO层，基于所述初始恢复信号再次恢复所述服务终端的信号。
  26. 根据权利要求25所述的基站，其中，所述一个或多个处理器进一步被配置为：基于所述服务终端的信号的到达角来确定用于所述服务终端的接收权矢量，以及通过使用所述接收权矢量获得所述服务终端的初始恢复信号。
  27. 根据权利要求26所述的基站，其中，所述一个或多个处理器进一步被配置为：
    确定所述干扰终端发送的信号和噪声的协方差矩阵；
    通过确定的所述服务终端的信号的到达角来形成用于所述服务终端的上行链路导向矢量；以及
    使用所确定的协方差矩阵以及所形成的上行链路导向矢量来确定用于所述服务终端的所述接收权矢量。
  28. 根据权利要求25所述的基站，所述一个或多个处理器进一步被配置为：
    在智能天线层，生成等效MIMO信道；以及
    在MIMO层，对所述等效MIMO信道进行噪声白化处理，并且对所述初始恢复信号进行白化处理。
  29. 根据权利要求25所述的基站，其中，所述一个或多个处理器进一步被配置为：根据迫零算法或最小均方误差算法从所述初始恢复信号来恢复所述服务终端的信号。
  30. 根据权利要求18-24中任一项所述的基站，所述一个或多个处理器进一步被配置为：
    基于确定的服务终端的信号的到达角来确定用于所述服务终端的发射权矢量；以及
    使用所确定的发射权矢量对用于所述服务终端的信号进行加权。
  31. 根据权利要求30所述的基站，其中，所述一个或多个处理器进一步被配置为：
    确定由所述基站发送至所述干扰终端的信号的协方差矩阵；
    通过确定的所述服务终端的信号的到达角来形成用于所述服务终端的下行链路导向矢量；以及
    使用所确定的协方差矩阵以及所形成的下行链路导向矢量来确定用于所述服务终端的所述发射权矢量。
  32. 根据权利要求30所述的基站，其中，所述一个或多个处理器进一步被配置为：
    基于来自所述服务终端的信道大尺度衰落系数以及用于所述服务终端的发射权矢量来获得预编码矩阵；以及
    使用所述预编码矩阵对用于所述服务终端的信号进行加权，
    其中，所述信道大尺度衰落系数是由所述服务终端基于所述基站发送的导频而估计的。
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