JP2011229171A - Wireless base station device, terminal device and wireless communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless base station device, a terminal device and a wireless communication method thereof that can easily perform allocation processing of a terminal device to be connected in spatial multiplexing, and that can reduce processing time in the wireless base station device that performs spatial multiplexing transmission to a plurality of terminal devices, the terminal device that responds to spatial multiplex transmission, and the wireless communication method thereof.SOLUTION: A wireless base station device 1 comprises a plurality of transmission weight generation unit 6-1 to 6-n that generate a transmission weight information group for performing spatial multiplex transmission by a different algorithm based on channel information to a plurality of terminal devices 2-1 to 2-s which have one or more antennas to perform spatial multiplex transmission; and a beam selection unit 7 that selects either transmission weight information of a plurality piece of transmission weight information generated by the algorithm. The wireless base station device 1 performs spatial multiplex transmission using the selected transmission weight information as transmission weight.

Description

  The present invention relates to a radio base station apparatus that performs spatial multiplexing transmission to a plurality of terminal apparatuses, a terminal apparatus that supports spatial multiplexing transmission, and a radio communication method thereof.

  In recent years, there has been a great increase in demand for higher capacity and higher speed of wireless communication, and research on methods for further improving the effective utilization efficiency of finite frequency resources has become active. As one of the methods, a technique using a spatial domain is attracting attention.

  One of the spatial domain utilization techniques is an adaptive array antenna (adaptive antenna), and the desired wave signal is adjusted by adjusting the amplitude and phase by a weighting coefficient (hereinafter referred to as “weighting”) to be multiplied with the received signal. Is received strongly and the interference wave signal is suppressed, so that co-channel interference can be reduced and the system capacity can be improved.

  Another spatial domain utilization technique uses spatial orthogonality in the propagation path, so that different data sequences can be transmitted to different terminal devices using the same time, the same frequency, and the same code physical channel. It is a spatial multiplexing transmission technology for transmission.

  Information on the spatial multiplexing transmission technique is disclosed in Non-Patent Document 1 and the like. In the spatial multiplexing transmission radio base station apparatus and terminal apparatus using this technique, if the spatial correlation coefficient between the terminal apparatuses is lower than a predetermined value, Spatial multiplexing transmission is possible, and the throughput of the wireless communication system and the number of simultaneous users can be improved.

T.A. Ohgane et al, “A study on a channel allocation scheme with an adaptive array in SDMA,” IEEE 47th VTC, Page. 725-729, vol. 2 (1997)

  However, in the configuration of the conventional spatial multiplexing transmission radio base station and terminal device, the terminal device that detects the spatial correlation coefficient between the terminal devices and should spatially multiplex connect the terminal devices having a spatial correlation coefficient smaller than a predetermined value. (Hereinafter, this “selection” operation is referred to as “assignment”) is required in the radio base station apparatus.

  Also, the spatial correlation coefficient has the property of changing with time due to changes in the propagation environment accompanying movement of the terminal device or peripheral objects, so the spatial correlation coefficient information is detected relatively frequently or periodically. Needed to be updated. For this reason, there has been a problem that the detection processing of the spatial correlation coefficient and the allocation processing of the terminal device to be spatially multiplexed are complicated. In addition, there is a problem that the processing delay associated therewith becomes long.

The present invention solves the above-described conventional problem. In the radio base station apparatus, a plurality of transmission weight generation units for generating transmission weight information based on a plurality of different algorithms are prepared in advance, and channel information from the terminal apparatus is prepared. Based on the predicted SINR (Signal-to-Interference and Noise power Ratio) value obtained from the above, the optimum transmission weight information is selected. As a result, by selecting an algorithm that provides the best communication quality for various spatial correlation coefficient conditions between terminal devices attempting to perform spatial multiplexing, the reception quality by spatial multiplexing transmission is made to a certain level of quality. can do. In addition, due to this effect, it is possible to easily perform allocation processing of terminal devices to be spatially multiplexed, and accordingly, a radio base station device and terminal device capable of reducing processing time, and a radio communication method thereof The purpose is to provide.

  In order to solve the above-described conventional problems, the radio base station apparatus of the present invention is used to form a transmission beam to be transmitted to the plurality of terminal apparatuses based on channel information for the plurality of terminal apparatuses to be spatially multiplexed. A plurality of transmission weight generation units that generate transmission weight information by different algorithms, and a beam selection unit that selects any one of the transmission weight information generated by the algorithm are provided.

  With this configuration, the optimal transmission weight according to various spatial correlation conditions detected by channel information during spatial multiplexing transmission to multiple terminal devices is optimal from those generated by multiple different transmission weight generation algorithms Can be selected.

  Further, the radio base station apparatus of the present invention uses, based on channel information for a plurality of terminal apparatuses to be subjected to spatial multiplexing transmission, transmission weight information used for forming a transmission beam to be transmitted to the plurality of terminal apparatuses using different algorithms. It is good also as a structure which has the some transmission weight production | generation part to produce | generate and the beam selection part which selects the transmission weight production | generation part which has a specific algorithm beforehand based on the said channel information.

  With this configuration, during spatial multiplexing transmission to multiple terminal devices, a transmission weight suitable for various spatial correlation conditions detected by channel information is selected and generated from a plurality of different transmission weight generation algorithms. can do.

  In addition, the terminal device of the present invention is based on a channel estimation unit that performs channel estimation based on a previously known signal sequence assigned to each spatially multiplexed signal, and channel information obtained from the channel estimation unit. In addition, a spatial demultiplexing unit having a function of generating a reception weight for separating and outputting a desired signal from the spatial multiplexed signal is provided.

  With this configuration, at the time of spatial multiplexing transmission to a plurality of terminal apparatuses, it is possible to separate and receive a spatially multiplexed signal using a known signal sequence for each transmission signal on the terminal apparatus side. As a result, in particular, when transmission weight generation is performed based on channel information including an error on the radio base station apparatus side, a spatially multiplexed signal is generated using a known signal sequence for each transmission signal on the terminal apparatus side. Separate reception is possible.

  In addition, the terminal device of the present invention has a channel estimation unit that performs channel estimation based on a previously known signal sequence inserted for each spatially multiplexed signal, and a channel estimation matrix obtained from the channel estimation unit. The left singular vector corresponding to the maximum singular value obtained by the value decomposition may have a spatial demultiplexing unit having a function of generating a reception weight for separating and outputting a desired signal from the spatial multiplexed signal.

  With this configuration, at the time of spatial multiplexing transmission to a plurality of terminal apparatuses, it is possible to separate and receive a spatially multiplexed signal using a known signal sequence for each transmission antenna on the terminal apparatus side. As a result, in particular, when using a transmission weight that enhances the reception quality to a desired terminal device after adding a constraint condition that minimizes interference with the other terminal device, the co-channel interference wave for the other terminal device is It is possible to suppress and maximize the reception power of the spatially multiplexed signal component.

Further, the wireless communication method of the present invention extracts channel information between the terminal device and the wireless base station from a received signal from the terminal device, and a plurality of spatial multiplexing transmissions to be performed based on the extracted channel information. Obtaining a spatial correlation coefficient between terminal devices;
A first method for generating a transmission weight using an algorithm for generating a transmission weight that enhances reception quality to a desired terminal device after adding a constraint condition that minimizes interference with other terminal devices;
A second method using an algorithm for generating a transmission weight that improves reception quality to a desired terminal device without adding a constraint condition of reducing interference with other terminal devices; and
From the third method of generating transmission weights using an algorithm that generates a single transmission weight,
And a step of selecting a method with the best communication quality according to the spatial correlation coefficient obtained in the step based on a predetermined selection processing method.
This configuration makes use of the fact that there is a specific relationship between the spatial correlation coefficient vs. communication quality characteristics of three different transmission weight generation methods, and this characteristic is divided into a plurality of sections in advance. The method selection processing method can be set so that the method with the best is selected.

  The present invention can select a transmission weight generation method suitable for a spatial correlation situation between terminal devices, and enables spatial multiplexing transmission that is robust to the spatial correlation situation between terminals, based on a conventional spatial correlation coefficient. Simplification of the allocation process can be achieved. Accordingly, there is provided a radio base station apparatus, a terminal apparatus, and a radio communication method that have the effect of simplifying the radio base station apparatus and reducing the processing time for spatial multiplexing transmission control and improving the system capacity by spatial multiplexing transmission. It can be provided.

Configuration diagram of radio base station apparatus and terminal apparatus according to first embodiment of the present invention (A) Detailed configuration diagram of terminal apparatus having a plurality of receiving unit antennas according to the first embodiment of the present invention (b) Terminal having one receiving unit antenna according to the first embodiment of the present invention Detailed configuration diagram of the device The flowchart which shows the spatial multiplexing transmission operation | movement based on the 1st Embodiment of this invention. (A) Arrangement diagram of antenna elements of radio base station antenna used for simulation of correlation coefficient and communication quality in three algorithms according to the first embodiment of the present invention (b) First embodiment of the present invention (C) Correlation coefficient in the three-method algorithm according to the first embodiment of the present invention Model diagram showing the state of radio wave propagation between the radio base station antenna and the receiving unit antenna used in the communication quality simulation (d) Correlation coefficient and communication quality in the three algorithms according to the first embodiment of the present invention (E) A model diagram showing the beam width on the transmitting end side used in the simulation of the three methods according to the first embodiment of the present invention. Model diagram showing a beam width at the receiving end using the simulation of the communication quality and correlation coefficient in Gorizumu The figure which shows the simulation conditions which concern on the 1st Embodiment of this invention Simulation result graph of correlation coefficient and communication quality when Rice factor K = 3 dB in the three-method algorithm according to the first embodiment of the present invention Simulation result graph of correlation coefficient and communication quality when Rice factor K = 6 dB in the three-method algorithm according to the first embodiment of the present invention Simulation result graph of correlation coefficient and communication quality when Rice factor K = 9 dB in the three-method algorithm according to the first embodiment of the present invention (A) Schematic diagram showing the state of spatial multiplexing transmission of the first transmission data frame sequence according to the first embodiment of the present invention in terms of time axis and spatial axis. (B) In the first embodiment of the present invention. Configuration diagram of the first transmission data frame sequence (A) Schematic diagram showing the state of spatial multiplexing transmission of the second transmission data frame sequence according to the first embodiment of the present invention in terms of time axis and spatial axis. (B) In the first embodiment of the present invention. Configuration diagram of the second transmission data frame sequence Configuration diagram of radio base station apparatus and terminal apparatus according to second embodiment of the present invention Configuration diagram of radio base station apparatus according to third embodiment of the present invention The block diagram of the terminal device which concerns on the 3rd Embodiment of this invention Configuration diagram of radio base station apparatus according to fourth embodiment of the present invention The block diagram of the terminal device which concerns on the 4th Embodiment of this invention Another block diagram of the terminal device which concerns on the 4th Embodiment of this invention

  Hereinafter, a radio base station apparatus and a terminal apparatus according to embodiments of the present invention will be described with reference to the drawings.

  Here, in the following description, a component, unit, or device having a plurality of the same components is designated by the same number when there is no need to indicate which component, unit, or device in the description. When it is difficult to understand the explanation unless a number is assigned to each of a plurality of components or units or devices, a hyphen is added after the first number and a second number is assigned. To do.

  For example, if the description can be understood without clearly indicating which device it is, it is referred to as the terminal device 2, and if the description is difficult to understand, the terminal devices 2-1, 2-2, 2-s are used. Shall be called.

(Embodiment 1)
FIG. 1 shows a radio base station apparatus and a terminal apparatus according to the first embodiment of the present invention. In FIG. 1, each of the terminal devices 2-1 to 2-s has a plurality of antennas 20-1 to 20-j, a plurality of antennas 20-1 to 20-k, and a plurality of antennas 20-1 to 20-s. However, only one antenna may be used. FIG. 2A shows a detailed configuration diagram of a terminal device having a plurality of antennas on the receiving side of the terminal device, and FIG. 2B shows a detailed configuration diagram of a terminal device having only one antenna.

FIG. 1 is a diagram illustrating configurations of the radio base station device 1 and the terminal devices 2-1 to 2-s according to the first embodiment of the present invention. Hereinafter, in the present embodiment, in the transmission (hereinafter referred to as downlink) from the radio base station apparatus 1 to the terminal apparatuses 2-1 to 2-s, Ns spatial streams are converted into s terminal apparatuses. A description will be given of the case of transmission toward (where Ns ≧ s and Ns is a natural number).

  In FIG. 1, a radio base station apparatus 1 according to an embodiment of the present invention generates a transmission signal generation unit 3- that generates a transmission data sequence for terminal apparatuses 2-1 to 2-s to be subjected to spatial multiplexing transmission. 1 to 3 -s and a channel information acquisition unit 4 for extracting downlink estimated channel information from received signals from the terminal devices 2-1 to 2 -s, and a weight determination unit for determining transmission weights. Transmission weight generation units 6-1 to 6-n that generate transmission weight information based on different generation algorithms, and a plurality of transmission weight information groups generated by the transmission weight generation units 6-1 to 6-n Based on the transmission weight determination unit 5 including the beam selection unit 7 that selects the optimal transmission weight information and the selected transmission weight information, the transmission power of each spatial stream is determined, and transmission power control information is transmitted. A transmission power determining unit 8 that performs transmission, and a transmission beam that multiplies each transmission data sequence by a transmission weight using the selected transmission weight information to form a specific transmission beam, and converts the multiplied signal into a high-frequency signal. Based on the transmission power control information of each spatial stream determined by the forming unit 9 and the transmission power determination unit 8, the output signals of the transmission signal generation units 3-1 to 3-s are multiplied by a predetermined power coefficient. Power coefficient multipliers 10-1 to 10-s and radio base station antennas 11-1 to 11-s that radiate high-frequency signals from the transmission beam forming unit 9 to a transmission medium (not shown) are provided.

  2A, a terminal apparatus 2-A according to an embodiment of the present invention having a plurality of antennas includes a transmission unit 210, a transmission unit antenna 216, a reception unit 220, and reception unit antennas 20-1 to 20-m. It has.

  The transmission unit 210 performs predetermined data processing on the data input unit 214 to which data information to be transmitted by the terminal user is input and the channel estimation information transmitted from the channel estimation unit 222, and converts the data into a high frequency signal. A transmission unit 212.

  The reception unit 220 corresponds to each of the reception unit antennas 20-1 to 20-m, and receives the units 221-1 to 221-1 that convert high-frequency signals received by the reception unit antennas 20-1 to 20-m into baseband signals. 221-m, a channel estimation unit 222 that estimates channel response information of a channel in the downlink from a plurality of baseband signals, and a desired signal from a spatially multiplexed signal based on the channel response information obtained by the channel estimation unit 222 Spatial demultiplexing unit 223 that separates and extracts, demodulating unit 224 that restores a transmission data sequence from a desired signal that is separated and received, and outputs the restored reception data sequence to another device or uses a terminal device A data output unit 225 for transmitting the information to a person.

  Here, although the transmission unit antenna 216 and the reception unit antennas 20-1 to 20-m are treated as different ones, they may share the same antenna.

  In FIG. 2B, the terminal apparatus 2-B according to the embodiment of the present invention having only one antenna includes a transmission unit 210, a transmission unit antenna 216, a reception unit 230, and a reception unit antenna 20-1. Yes.

  The difference from FIG. 2A is that, in the receiving unit 230, since the terminal device 2-B is only a single receiving unit antenna 20-1, the spatial demultiplexing unit 223, which is a spatial domain interference cancellation process, is provided. This is a configuration that does not include. Similarly to FIG. 2A, the transmission unit antenna 216 and the reception unit antenna 20-1 are treated as different ones, but they may share the same antenna.

Next, operations of the radio base station apparatus 1 and the terminal apparatus 2-A or 2-B will be described. First, on the assumption that the downlink channel information is estimated by the terminal devices 2-1 to 2-s, the operation of notifying this information to the radio base station device 1 will be outlined.

  First, in the transmission unit 210 of the terminal device 2-A or 2-B, channel information of a propagation path (not shown) estimated by the channel estimation unit 222 is guided to the transmission unit 212 and controlled by the transmission unit 212. It is transmitted to the radio base station apparatus 1 via the channel or the broadcast channel. That is, the control channel signal or broadcast channel signal carrying the channel information is guided to the transmission unit antenna 216, and is emitted from the transmission unit antenna 216 to the propagation path (not shown) toward the radio base station apparatus 1. .

  Here, the control channel or the broadcast channel is a communication channel for exchanging information for effectively operating the radio base station apparatus 1 and the terminal apparatus 2-A or 2-B, and the terminal apparatus 2-A. Alternatively, the communication channel is different from the communication channel through which information to be transmitted / received by the 2-B user is exchanged.

  Information to be transmitted by the user of the terminal device 2-A or 2-B is input from the data input unit 214 to the transmission unit 212, subjected to predetermined signal processing, converted into a high-frequency signal, and then transmitted. It is sent to the radio base station apparatus 1 via the unit antenna 216.

  After that, in the radio base station apparatus 1, the channel information acquisition unit 4 transmits the radio base station antennas 11-1 to 11- from the plurality of terminal apparatuses 2-1 to 2-s having the configuration of the terminal apparatus 2-A or 2-B. Channel information transmitted from each of the terminal devices 2-1 to 2 -s is extracted from the control channel signal or broadcast channel signal transmitted toward s and output to the transmission weight determination unit 5.

  Next, based on the notified downlink channel information, a transmission signal addressed to (assigned) terminal apparatuses 2-1 to 2-s to be spatially multiplexed is multiplied by a predetermined transmission weight to be spatially multiplexed. Outlined is the operation performed.

  First, in the radio base station apparatus 1, the channel information acquisition unit 4 is directed from the terminal apparatuses 2-1 to 2-s that are to be spatially multiplexed (assigned) to the radio base station antennas 11-1 to 11-s. The channel information transmitted from each of the terminal devices 2-1 to 2 -s is extracted from the transmitted control channel signal or broadcast channel signal, and is output to the transmission weight determining unit 5. The channel information extracted at this time is downlink channel information from the radio base station apparatus 1 to the terminal apparatuses 2-1 to 2-s.

  Next, the transmission weight determination unit 5 transmits different transmission weights to the terminal devices 2-1 to 2-s to be spatially multiplexed in order to perform optimal signal transmission according to the correlation state between the terminal devices. A plurality of types of transmission weight generation information are generated by a plurality of transmission weight generation units 6-1 to 6-n having a generation algorithm. Thereafter, the beam selection unit 7 maximizes a predetermined criterion from among a plurality of transmission weight generation information groups generated by the first to nth transmission weight generation units 6-1 to 6-n. The transmission weight information is selected, and this information is output to the transmission power determination unit 8 and the transmission beam forming unit 9.

  Next, the transmission power determination unit 8 calculates a power distribution coefficient for determining transmission power for each spatial multiplexing stream, based on the input transmission weight information.

  On the other hand, transmission signal generation sections 3-1 to 3-s generate signals (hereinafter referred to as transmission data sequences) addressed to terminal devices 2-1 to 2-s to be spatially multiplexed (assigned). After being subjected to predetermined signal processing, it is output.

  Then, in the power coefficient multipliers 10-1 to 10-s, the signal output of each of the transmission signal generation units 3-1 to 3-s is multiplied by the power distribution coefficient calculated by the transmission power determination unit 8.

  Next, the transmission beam forming unit 9 applies a predetermined (selected) to each transmission data frame sequence signal (described later) multiplied by the power distribution coefficient based on the transmission weight information from the beam selection unit 7. (B) Generate baseband symbol data multiplied by transmission weights forming a beam. After that, digital data, which is baseband symbol data, is digital / analog converted by a digital / analog converter (not shown), a band limiting filter and a frequency converter, further band-limited, and then converted to a carrier frequency. Outputs high frequency signals.

  The radio base station antennas 11-1 to 11-s emit the supplied high-frequency signals to a propagation path (space) (not shown) toward the terminal devices 2-1 to 2-s to be spatially multiplexed.

  Here, the operation of the reception processing in the terminal apparatuses 2-1 to 2-s for the signals that are spatially multiplexed in the radio base station apparatus 1 will be described later, and before that, the radio base station apparatus in the downlink Regarding the spatial multiplexing transmission in FIG. 1, after explaining the operation flow from the viewpoint including scheduling, the operation in each step, determination criteria, weight generation algorithm, etc. will be described in detail.

  FIG. 3 is a flowchart showing a spatial multiplexing transmission operation in the downlink radio base station apparatus 1. Hereinafter, the spatial multiplexing transmission operation in the radio base station apparatus 1 in the downlink will be described using FIG. 1 and FIG. In order to make the contents easy to understand, the outline of the operation will be explained first, and then the detailed items will be explained.

First, s or less terminal devices 2-k to be preferentially connected by downlink transmission are determined for a plurality of terminal devices 2-1 to 2-s by predetermined packet scheduling (step S30). Here, it is assumed that the terminal device 2-k having k = 1 to s (s is a natural number) is preferentially assigned. Here, as a scheduling method, a signal-to-interference wave power ratio (hereinafter referred to as SIR (Signal-to-Interference), which is one of values indicating the reception quality of the terminal device.
There are a Maximum CIR method and a Proportional Fairness method, which are packet scheduling based on (Ratio)). Jalali et al, “Data Throughput of CDMA-HDR
a High Efficiency-High Data Rate Personal Communication Wireless System "IEEE VTC2000-Spring, pp. 1854-1858 is applied.

  Next, the channel information acquisition unit 4 acquires downlink channel information for the allocated terminal apparatuses 2-1 to 2-s (step S31). In this case, in each of the terminal devices 2-1 to 2-s, the observed channel information is fed back to the radio base station device 1 in advance, or in the case of TDD (Time division duplex), the relativity of the propagation path is used. It is possible to acquire downlink channel information based on transmission signals of known signal sequences in the uplink from the terminal apparatuses 2-1 to 2-s.

The following was obtained assuming flat fading (indicating an environment in which the influence of fading is all the same in the frequency band to be considered, that is, an environment state in which the influence of multipath does not need to be considered). As channel information, a channel estimation matrix for the k-th terminal apparatus 2-k is denoted as H (k). The channel estimation matrix is (the k-th terminal device 2-
The number of receiving antennas Nr (k) at k is a matrix composed of rows (number of radio base station antennas Nt), and the jth row and sth column elements of the channel estimation matrix are from the sth antenna of the radio base station device 1. This represents a complex channel response when a signal to be transmitted is received by the j-th receiving antenna 20 of the terminal device 2-k.

  Next, the first to nth transmission weight generation units 6-1 to 6-n generate a plurality of transmission weight information groups based on different weight generation algorithms (step S32).

  Next, the beam selection unit 7 selects transmission weight information that maximizes a predetermined criterion from among a plurality of transmission weight information groups (step S33). Here, transmission weight information for the k-th terminal device 2-k by the n-th transmission weight generation unit 6-n is defined as a transmission weight Wn (j). Here, j = 1 to Nu (k), Wn (j) is a column vector having Nt elements, and its norm is normalized to 1 (except for zero weight). . Nu (k) is the number of spatially multiplexed streams for the terminal device 2-k. Furthermore, k = 1 to s, and the total number of Nu (k) for all the terminal devices 2-1 to 2-s to be connected simultaneously by spatial multiplexing transmission is that when the number of all spatial multiplexing streams is Ns, It shall be equal to Ns.

  Next, the transmission power determination unit 8 determines the transmission power distribution coefficient for each spatial stream based on the transmission weight information selected by the beam selection unit 7. In this case, it is necessary to set the total transmission power of each stream so as not to exceed a predetermined transmission power value. Then, in the power coefficient multipliers 10-1 to 10-s, the signal output of each of the transmission signal generation units 3-1 to 3-s is multiplied by the power distribution coefficient determined by the transmission power determination unit 8 (step) S34).

  Next, based on the transmission weight information from the beam selection unit 7, the transmission beam forming unit 9 multiplies each transmission data frame sequence signal by the transmission weight for forming the selected beam. Generate symbol data. The digital data that is the baseband symbol data is digital / analog converted by a digital / analog conversion (not shown), a band limiting filter and a frequency converter, and further subjected to a band limiting process. The converted high frequency signal is output. Further, the radio base station antennas 11-1 to 11-s emit the supplied high frequency signal to a propagation path (space) (not shown) (step S35).

The above is a schematic description of the spatial multiplexing transmission operation in the downlink radio base station apparatus 1 shown in the flowchart of FIG. Next, the following items [1] to [3] will be described in further detail.
[1] Detailed description of a transmission weight generation algorithm incorporated in the transmission weight generation units 6-1 to 6-n.
[2] Detailed description of the transmission weight information selection method in the beam selection unit 7.
[3] Detailed description of a method for determining a transmission power distribution coefficient.

  [1] Detailed description of a transmission weight generation algorithm incorporated in the transmission weight generation units 6-1 to 6-n.

  Here, the transmission weight generation algorithm incorporated in the transmission weight generation units 6-1 to 6-n will be described in detail. The transmission weight generation units 6-1 to 6-n are roughly divided into the following three types of different weight generation algorithms.

Method (A) An algorithm for generating a transmission weight that enhances reception quality to a desired terminal device 2 after adding a constraint condition that minimizes interference with other terminal devices 2.

  Method (B) An algorithm for generating a transmission weight that enhances reception quality to the desired terminal device 2 without adding a constraint that reduces interference with the other terminal device 2.

  Method (C) An algorithm for generating a single transmission weight.

  It has been found by simulation this time that by using these three different algorithms, it is possible to generate various transmission weights that can correspond to the correlation status between terminal devices. 6 to 8 show changes in the emission angle difference AOD (2) (described later) between the terminal devices using the conditions shown in FIG. 5 in the directional channel model shown in FIGS. 4 (a) to 4 (e). FIG. 6 is a graph showing a simulation result of the relationship between the correlation coefficient and the communication quality when the correlation coefficient between the terminal devices is changed. As the communication quality evaluation value, the required transmission power satisfying the bit error rate (BER) = 1E-3 is used (however, normalization is performed with the transmission power at the time of one-antenna transmission), and the smaller of this value Is a method with good communication quality.

  4A shows the antenna element arrangement of the radio base station antenna 60 used in the simulation, and FIG. 4B shows the antenna arrangement of the reception unit antenna 62 of the terminal apparatus. In the radio base station antenna 60, four transmission antenna elements 60-1 to 60-4 are arranged on a straight line at positions spaced at equal intervals by the distance Dt, and the reception unit antenna 62 receives two elements. Antenna elements 62-1 to 62-2 are arranged separated by a distance Dr.

  In FIG. 4C, the radio wave radiated from the radio base station antenna 60 is reflected by the obstacle 64 at the reflection point 65 and received by the receiving unit antenna 62 via the path 67-a and the path 67-b. FIG. The angle from the normal on the obstacle 64 side of the straight line where the transmitting antenna elements 60-1 to 60-4 are lined up to the path 67-a indicating the direction of the radio wave radiated toward the obstacle 64 is defined as an emission angle difference AOD. An angle from a straight line normal to the obstacle 64 side defined between the receiving antenna elements 62-1 to 62-2 to a path 67-b indicating the direction of the radio wave reflected from the reflection point 65 of the obstacle 64 Is defined as an incident angle difference AOA.

  The communication path between the radio base station antenna 60 and the receiving unit antenna 62 of the kth terminal device (user) is called the kth user path, and the AOD and AOA at this time are AOD (k) and AOA. (K) is displayed. The kth user path includes a path 67-a and a path 67-b.

  4D schematically shows the beam width on the transmission end side of the path 67-a, and FIG. 4E schematically shows the beam width on the reception end side of the path 67-b. The horizontal axis indicates the beam width, and the vertical axis indicates the radio wave intensity. The width between two points 3 dB lower than the peak value of the radio field strength is defined as the beam width, the angle spread on the transmission end side is defined as AS (t), and the angle spread on the reception end side is defined as AS (r). When the radio base station antenna height is higher than the surrounding building height, AS (r) tends to be larger than AS (t).

  When the correlation coefficient value at the intersection of the method (B) and the method (A) is E1, and the correlation coefficient value at the intersection of the method (B) and the method (C) is F1, in the interval where the correlation coefficient value is 0 to E1, The communication quality of the method (B) is the best, the communication quality of the method (A) is the best in the section where the correlation coefficient value is E1 to F1, and the communication of the method (C) is performed in the region where the correlation coefficient value is F1 to F1. The signal quality of each method changes so that the quality is the best, and the spatial correlation coefficient versus communication quality characteristic shown in FIG. 6 is drawn.

FIG. 6 shows values when the rice factor K = 3 dB. In FIG. 6, the horizontal axis indicates the spatial correlation coefficient between the terminal devices, and the vertical axis indicates the required transmission power that satisfies the bit error rate (BER) = 1E-3 as the signal quality. The square (black) points are plots of the spatial correlation coefficient between the terminal devices and the signal quality when the method (A) is used, and the triangle (black) points use the method (B). In this case, the spatial correlation coefficient between the terminal devices and the signal quality are plotted. Furthermore, the circle (white) point is a plot of the spatial correlation coefficient between the terminal devices and the signal quality when the method (C) is used.

  FIG. 7 shows the case where the rice factor K = 6 dB, and FIG. 8 shows the case where the rice factor K = 9 dB. In any case, the same can be said as in FIG. That is, even if the rice factor K is changed, the spatial correlation coefficient versus communication quality characteristic can be divided into a plurality of three or more sections, and there is a method in which the communication quality is the best in each section.

  Here, the rice factor K is a parameter indicating a prospect situation of the radio base station antenna 60 and the receiving unit antenna 62. In general, when the rice factor K is large, the radio base station antenna height is high, and it is assumed as a propagation model in a cellular environment that is relatively likely to be a line-of-sight environment, and when the rice factor K is small, the radio base station antenna 60 Both the receiving unit antenna 62 is assumed to be a propagation model when it is lower than the surrounding building height and is not in a line-of-sight environment.

  From these results, when the correlation between the terminal devices is low (for example, when the correlation coefficient is about 0 to 0.3), the degree of freedom of the plurality of antennas on the transmission side is used to improve the communication quality to the terminal device 2 The technique according to B is advantageous. In addition, when the correlation is very high (for example, when the correlation coefficient is about 0.8 to 1), the method (C) that does not perform spatial multiplexing transmission is advantageous. In the case of an intermediate correlation between them (for example, when the correlation coefficient is about 0.4 to 0.6), the method by the method A using the degrees of freedom of a plurality of antennas on the transmission side for mutual interference cancellation between terminals is advantageous. It is. As described above, it is possible to perform spatial multiplexing transmission while maintaining high communication quality by appropriately selecting algorithms having different properties.

  Here, the method (A) type algorithm is (A-1) a null beam method (ZF beam (Zero-Forcing, zero forcing, beam), MMSE beam (Minimum-Mean- Square-Error, least square error, beam))) or when the terminal device 2 has a plurality of antennas, (A-2) a block orthogonalization weight method and (A-3) a reception weight at the time of reception Assuming that the signal is received with the maximum ratio combining weight, one or a plurality of combined weight generation methods for performing block orthogonalization are included.

  The method (B) type algorithm has (B-1) eigenvector beam technique (single value obtained by singular value decomposition of the channel estimation matrix H (k) for a specific k-th terminal apparatus 2-k). On the other hand, a right singular vector corresponding to a large singular value corresponding to the number of spatial multiplexing Nu (k) to a specific k-th terminal apparatus 2-k is used), (B-2) a plurality of different main beam directivities One or a plurality of techniques for selecting a beam closest to the direction of a specific terminal device 2 in which the main beam direction is spatially multiplexed from a fixed beam pattern (orthogonal beam pattern or a beam pattern having different main beam directions at equal intervals) This method is included.

  In the method (C) type algorithm, the eigenvector beam is transmitted only to one highest priority terminal device 2 among the plurality of terminal devices 2-1 to 2-s. , Using a single transmit weight technique that generates zero weights of all zero elements.

Hereinafter, each weight generation method of the method (A) type algorithm will be further described in detail.

(A-1) In the case of a null beam technique in which nulls are directed toward other terminal devices 2:
When forming a ZF beam, the transmission weight Wk (j) for the k-th terminal apparatus 2-k is calculated as follows. That is, except for the channel estimation matrix H (k) of the k-th terminal apparatus 2-k, for all channel estimation matrices H (l) for other terminal apparatuses 2 to be connected simultaneously, A transmission weight Wk (j) that satisfies the conditions shown is calculated. Here, j = 1 to Nu (k), Nu (k) is the number of spatially multiplexed streams for the terminal device 2-k, and s is the number of all terminal devices that are spatially multiplexed.

However,
For example, when the number of spatial multiplexed streams for the terminal device 2-1 is Nu (1) = 3, three elements constituting the column vector W1 (j) that is a transmission weight for the terminal device 2-1, W1 A value satisfying (Equation 1) is calculated for (1) to W1 (3).

  As described above, k is varied from 1 to s, and transmission weights for all terminal apparatuses 2-1 to 2-s are calculated. That is, a total of Ns transmission weights, which is the total number of all spatially multiplexed streams, is calculated.

If, on the assumption that the noise power [delta] ² are all equal in all of the receiving-side terminal apparatus 2 is set to a certain predetermined value, the signal-to-interference ratio (SIR at each of the terminal devices 2 forming the MMSE beam ) Is maximized, a transmission weight Wn (j) that satisfies the condition shown in (Expression 2) is generated. Here, j = 1 to s, and s is the total number of terminal apparatuses that are spatially multiplexed.

  Superscript “H” indicates a complex conjugate operator.

(A-2) In case of block orthogonal weight method:
The transmission weight Wn (j) for the k-th terminal device 2-k is calculated as follows. Here, j = 1 to Nu (k). First, except for the channel estimation matrix H (k) of the k-th terminal apparatus 2-k, the channel estimation matrix H (l) of other terminal apparatuses to be simultaneously connected (where l =
A matrix Dk shown in (Expression 3) is generated as a new matrix based on l ≠ k) with 1, 2,... S.

  Next, a right singular matrix Vk shown in (Expression 4) obtained by singular value decomposition of Dk is obtained.

  The obtained right singular matrix Vk constitutes a matrix of Nt rows and Nt columns, and a matrix obtained by taking out the right singular vector corresponding to the singular value “0” (numerical value zero) is Rk. The matrix Rk consists of Nt rows and Nq columns. Here, Nq is expressed by (Equation 5).

  Eigenvector beam transmission is performed based on a new matrix Ek shown in (Equation 6) using a matrix Rk composed of Nt rows and Nq columns.

  That is, the matrix Ek is composed of Nr (k) rows and Nq columns, and is the number of spatially multiplexed streams transmitted to the k-th terminal apparatus 2-k among the right singular vectors obtained by singular value decomposition of Ek. Nu (k) singular values are selected in descending order, and a transmission weight Wn (j) is set using the right singular vector corresponding to the selected singular values.

  As described above, k is varied from 1 to s, and transmission weights for the terminal apparatuses 2-1 to 2-s are calculated. That is, a total of Ns transmission weights, which is the total number of all spatially multiplexed streams, is calculated.

(A-3) In the case of the combined weight generation method for performing block orthogonalization on the assumption that the reception weight at the time of reception is received with the maximum ratio combining weight:
The transmission weight Wn (j) for the k-th terminal device 2-k is calculated as follows. Here, j = 1 to Nu (k). First, as shown in (Expression 7), among the left singular matrix Uk obtained by singular value decomposition of the channel estimation matrix H (k) of the kth terminal apparatus 2-k, the kth terminal apparatus 2- Nu (k) singular values that are the number of spatial multiplexed streams to be transmitted to k are selected in descending order and the left singular vector corresponding to the selected singular value is used to generate the k-th terminal device 2- Assume a reception weight matrix Gk at k. The reception weight matrix Gk consists of Nr (k) rows Nu (k) columns.

  This is calculated for all terminal devices 2.

  Next, a channel estimation matrix H (m) excluding the channel estimation matrix H (k) and the reception weight matrix G (k) regarding the k-th terminal apparatus 2-k, and a reception weight matrix Gm, where m = 1 ˜s, m ≠ k), a new channel estimation matrix Dk shown in (Expression 8) is calculated.

  Next, a right singular matrix Vk shown in (Expression 4) is obtained for the obtained matrix Dk. The obtained right singular matrix Vk constitutes a matrix of Nt rows and Nt columns, and a matrix obtained by taking out the right singular vector corresponding to the singular value “0” (numerical value zero) is Rk. The matrix Rk consists of Nt rows and Nv columns. Here, Nv is expressed by (Equation 9).

Eigenvector beam transmission is performed based on the new matrix Ek shown in (Expression 6) using the matrix Rk composed of Nt rows and Nv columns. That is, the matrix Ek is composed of Nr (k) rows and Nv columns, and is the number of spatial multiplexed streams to be transmitted to the k-th terminal apparatus 2-k among the right singular vectors obtained by singular value decomposition of Ek. Select Nu (k) singular values in descending order,
The transmission weight Wn (j) is set using the singular right singular vector corresponding to the selected singular value. As described above, k is varied from 1 to s, and transmission weights for the terminal apparatuses 2-1 to 2-s are calculated. That is, a total of Ns transmission weights, which is the total number of all spatially multiplexed streams, is calculated.

  In addition, since this method (A-3) assumes that the reception weight at the time of reception is received by the maximum ratio combining weight, the constraint condition for forming the directivity null is relaxed, and the method (A-2) The present invention can be applied even when the total number of reception antennas provided in the terminal devices 2 connected simultaneously is larger than the number Nt of transmission antennas of the radio base station device 1. In the method (A-2), the number of reception antennas is a restriction condition when the transmission weight is formed. On the other hand, in this technique, the restriction condition when the number of spatially multiplexed streams forms the transmission weight. Therefore, in a certain terminal device 2-k, when the number of spatially multiplexed streams Nu (k) to the terminal device 2-k is smaller than the number of receiving antennas Nr (k), it is superior to the method of (A-2). The reception quality can be obtained.

[2] Detailed Description of Transmission Weight Information Selection Method in Beam Selection Unit 7 Here, a detailed description is given of the transmission weight information selection method in the beam selection unit 7. The beam selection unit 7 selects transmission weight information that maximizes a predetermined criterion from among a plurality of transmission weight information groups generated by the n-th to n-th transmission weight generation units 6-1 to 6-n. To do. As a determination criterion, a predicted value of a physical quantity indicating signal quality such as a signal-to-noise power ratio (hereinafter referred to as SNR) or a signal-to-interference wave power ratio (hereinafter referred to as SINR) received by the terminal device 2 is used.

  Therefore, a specific transmission weight selection method will be described using mathematical expressions. First, assuming that Ns spatial streams at time t are (Equation 10) and the transmission weight information generated by the nth transmission weight generation unit 6-n is selected, the signal Yn (t) to be transmitted is It shall be shown by (Formula 11). Here, k = 1 to Ns, and Yn (t) represents a column vector composed of Nt elements. Further, (Equation 12) represents the transmission power of each of the spatial multiplexed streams for the terminal devices 2-1 to 2-s. Here, it is assumed that equal power transmission is performed. Further, Wn (k) is a transmission weight (column vector of Nt elements) for the kth spatial stream (Equation 10) generated by the nth transmission weight generation unit 6-n.

Here, the subscript “k” indicates the k-th spatial stream, and k = 1, 2,..., Ns.

  Here, the subscript “k” indicates the k-th spatial stream, and k = 1, 2,..., Ns.

  Next, the received signal (Equation 13) in the terminal device 2 is predicted. The received signal (Expression 13) can be expressed as (Expression 14) using channel information H (k) for the k-th terminal apparatus 2-k.

  Here, when the number of antennas Nr (k) of the terminal device 2-k is 1, SINR is obtained by (Equation 15). Note that δ is noise power when it is assumed that Gaussian additive noise is added, and is treated as a predetermined fixed value hereinafter.

  When the terminal device 2-k has a plurality of antennas, SINR evaluation is performed using (Equation 16) assuming directivity formation by the reception weight R (k). Here, the reception weight R (k) indicates a column vector having Nr (k) elements for the number of reception unit antennas of the terminal device 2-k. In (Expression 16), the subscript “n” indicates the number when the user terminal, that is, each terminal device 2 that performs spatial multiplexing connection is numbered in order, and in this embodiment, the terminal device 2-1. Corresponds to ~ 2-s.

As a method for calculating a virtual reception weight in the terminal device 2, when an interference wave component exists, the MMSE method and the ZF method can be applied, and when the interference wave component does not need to be considered, Maximum ratio combining reception weight can be applied.

  When the method for calculating the transmission weight is the block orthogonal weight method, the number of spatially multiplexed streams for the terminal device 2-k among the singular values obtained by singular value decomposition of the channel estimation matrix H (k). Minute singular values may be selected in descending order, and the left singular vector corresponding to the selected singular value may be used.

  Further, there may be used a method of selecting a best combination of reception weight and transmission weight candidate by having a plurality of weight information candidates that can be used as the above-mentioned reception weight and performing respective SINR evaluations. In this case, the processing amount for SINR evaluation increases, but the best communication quality can be obtained under various propagation environment conditions.

  As described above, SINRn (k) of each user is calculated using Wn (k) shown in (Equation 16) as a variable. This is calculated by all the first to nth transmission weight generation units. Then, a transmission weight Ws (k) that is output information from the sth transmission weight generation unit 6-s that generates a transmission weight that maximizes the sum of the SINRn (k) of each user is selected. Here, k = 1 to Ns.

  Here, weighted addition according to the QoS (allowable delay, transmission request rate, etc.) of the spatially multiplexed stream to be spatially multiplexed may be performed. For example, for a user (terminal device) that needs real-time signal transmission with a small allowable delay, weighting is increased and signal transmission is performed with priority. As a result, the number of retransmission processes is reduced, and the overall system throughput can be improved.

  Moreover, you may perform the weighting addition according to a transmission request rate. For example, the system throughput as a whole can be improved by increasing the weight for a spatially multiplexed stream having a high transmission request rate and preferentially transmitting a signal having a high request rate.

  [3] Detailed description of a method for determining a transmission power distribution coefficient.

  Here, the transmission power distribution coefficient determination method will be described in detail. The power distribution can be simply performed by equal power distribution, but the application of the following methods (1) to (2) can improve the throughput or reduce the transmission power.

(1) Methods to improve capacity (throughput):
The SNR (k) is measured as the reception quality of the terminal device 2-k for the broadcast signal from the radio base station device 1, and the measurement information is notified to the radio base station device 1 in advance. A water-filling method based on theoretical capacity from each SNR (k) and channel estimation matrix (a method for preferentially allocating power to a stream having a good SNR value) is applied. Thereby, since the power distribution ratio for each spatial stream is determined, the ratio is set as a power distribution coefficient.

In this case, normally, the change of the modulation multi-value number and the coding rate (hereinafter referred to as MCS) is a discrete value, so it is more desirable to correct the power distribution ratio. In that case, the following correction method is used. That is, the received SINR in the terminal device 2-k when the calculated power distribution is performed is predicted, and when the predicted SINR exceeds the required SINR in the MCS that realizes the maximum rate, the surplus is Since power distribution more than necessary and sufficient is given to the terminal device 2-k, the surplus is distributed to the spatial streams for the other terminal devices 2. Conversely, the required SINR in the MSC that achieves the minimum rate.
Is less than, the power distribution ratio to the spatial streams for the other terminal devices 2 is reduced in order to preferentially distribute the power for the spatial streams for the terminal device 2-k.

(2) Technique for reducing transmission power:
First, SNR (k) is measured as the reception quality of the terminal device 2-k for the broadcast signal from the radio base station apparatus 1, and the measurement information is notified to the radio base station apparatus 1 in advance. Noise power is estimated from the obtained SNR (k), and SNRt (j) defined by (Equation 17) is predicted as the SNR at the time of spatial multiplexing stream transmission. Here, j = 1 to Nu (k), and Pa represents the ratio of the transmission power of the broadcast signal to the predetermined maximum power when transmitting the spatially multiplexed stream. Further, when the broadcast signal is transmitted from the nth antenna, h (k) is the number of antennas Nr (k) included in the receiving unit of the terminal device 2-k, which is composed of the nth column of H (k). Indicates a column vector consisting of the same number of elements.

  Next, in the radio base station apparatus 1, assuming that the table of correspondence between the reception quality (SNR) in the terminal apparatus 2 and the optimum MCS is owned in advance, the following processing is performed. First, according to the respective allowable delays required for QoS from all the terminal devices 2 to be connected simultaneously, power is distributed to the terminal devices in order from the highest priority of data transmission. Then, a required SNR satisfying a minimum transmission rate is determined from a combination of MCSs that realize a transmission rate satisfying an allowable delay, with a predetermined margin added.

  Next, the power distribution coefficient b (j) is determined so that SNRt (j), which is the SNR at the time of spatial multiplexing stream transmission, becomes substantially equal to the required SNR. When b (j) is smaller than 1, power is similarly distributed to other spatial streams or other terminal devices 2 to be simultaneously connected within a range not exceeding the remaining transmission power, and terminals to be simultaneously connected Transmission is not performed for the terminal device 2 that does not satisfy the required SNR in the device 2. Finally, the distribution is performed such that the sum of the power distribution coefficients b (k) is 1 or less.

  Next, the operation in the transmission signal generation units 3-1 to 3-s will be described in detail. First, in the first to s-th transmission signal generation units 3-1 to 3-s, signals addressed to the terminal devices 2-1 to 2-s to be spatially multiplexed (priority assigned) (hereinafter referred to as transmission data). Each of which is called a series. Then, each transmission data sequence is subjected to error correction coding using an error correction encoder, interleaver, puncture, and modulator (not shown), punctured, and interleaved. Symbol mapping is performed according to the modulation method. (Hereinafter, a signal subjected to symbol mapping is referred to as a symbol data series or a spatial stream individual data signal). Thereafter, a transmission signal having a predetermined frame configuration is generated by attaching a known pilot signal and control information in advance to each symbol data series. Hereinafter, this signal is referred to as a transmission data frame sequence.

  FIG. 9B is an example of a transmission data frame sequence configuration. Each of the transmission data frame sequences 500-1 to 500-s generated and output from the first to sth transmission signal generation units 3-1 to 3-s includes a control information unit C1 to Cs and a spatial stream unit. Each of the spatial stream sections K1 to Ks includes a spatial stream dedicated pilot signal section P1 to Ps and a spatial stream dedicated data signal section D1 to Ds.

  The control information units C1 to Cs are signals broadcast to all the terminal devices 2-1 to 2-s that are to be spatially multiplexed, and are transmitted omnidirectionally. In the control information sections C1 to Cs, the number of subsequent spatial streams and the ID information of the destination terminal device with respect to the spatial stream number, that is, information indicating which terminal device is a spatial stream including a transmission data sequence and Modulation format information such as an encoding method, an encoding rate, a modulation multi-level number, and a data length is included.

  On the other hand, the spatial stream units K1 to Ks are signals transmitted to the respective terminal devices 2-1 to 2-s using transmission weights, and are transmitted in a directional manner. In the spatial stream units K1 to Ks, spatial stream individual pilot signal units P1 to Ps composed of previously known pilot signal sequences are included in the spatial stream individual data signal unit including transmission data (individual data) addressed to each terminal apparatus. Although the preamble structure attached to the preceding stage is used, a postamble structure attached to the subsequent stage or a midamble structure attached to the middle of the spatial stream individual data signal unit may be used.

  FIG. 9A shows how the transmission data frame sequence is spatially multiplexed with respect to a plurality of terminal apparatuses 2-1 to 2-s (corresponding to the first user to the sth user). It is schematically shown on the axis and the space axis. After the same control information 40-1 to 40-s is omnidirectionally transmitted to all users (first user to sth user) to be spatially multiplexed, each user (first It is shown that the signals for each of (th user to s-th user) are transmitted directionally. The time from T1 to T2 corresponds to the time taken to transmit one transmission data frame sequence.

  FIG. 10 is an example of a second transmission data frame sequence configuration. The difference from the frame configuration of FIG. 9 is that the spatial stream section further includes spatial stream individual control information sections SC1 to SCs. Spatial stream individual control information sections SC1 to SCs include modulation format information of subsequent spatial stream individual data signal sections D1 to Ds, and are transmitted in a fixed predetermined modulation format.

  By using this configuration, it is not necessary for the control information units C1 to Cs to include the modulation format information of the subsequent spatial stream individual data signal units D1 to Ds, so the transmission amount in the control information units C1 to Cs is reduced. be able to. Furthermore, since the spatial stream individual control information units SC1 to SCs including the modulation format information of the spatial stream individual data signal units D1 to Ds are also transmitted in a directional manner, the terminal devices 2-1 to 2-s perform the spatial stream individual data. The reception error of the modulation format information of the signal parts D1 to Ds can be prevented. As a result, higher reception quality can be ensured.

  The above is the detailed description of the items [1] to [3].

  Next, the reception processing operation in the terminal devices 2-1 to 2-s for signals spatially multiplexed in the radio base station device 1 will be described with reference to FIG. Hereinafter, an operation after establishment of synchronization (frame and symbol synchronization) with the radio base station apparatus 1 will be described.

  First, in the terminal device 2-A, high-frequency signals received by the reception unit antennas 20-1 to 20-m are input to the reception units 221-1 to 221-m, respectively. The receiving units 221-1 to 221-m filter a desired band from a high-frequency signal, perform frequency conversion to a quadrature-detected baseband signal, and perform digital / analog conversion (hereinafter referred to as an A / D converter) to generate an I signal, Digital signal data (hereinafter referred to as complex baseband signal) composed of Q signals is output.

  The spatial demultiplexing unit 223 receives a data signal of a desired spatial stream number notified to the terminal device from one or more input complex baseband signals, and receives data of a spatial stream number other than that addressed to the terminal itself In order to suppress the signal, that is, the interference signal, to the extent that signal quality sufficient for removing or performing communication can be ensured, the following operation is performed.

  First, the channel estimation unit 222 separates and extracts all the spatial stream dedicated pilot signals at the arrival timing of pilot signals (hereinafter referred to as spatial stream dedicated pilot signals) that are transmitted accompanying the spatial streams. The channel estimation value of is calculated. Here, the m-th terminal apparatus 2-m that receives a spatially multiplexed signal includes Nr (m) reception unit antennas 20-1 to 20-m and Nr corresponding to each reception unit antenna. It is assumed that (m) reception units 221-1 to 221-m are provided.

  Output signal obtained as a result of receiving the k-th spatial stream dedicated pilot signal sequence (Equation 18) by the j-th receiving unit antenna 20-j and the receiving unit 221-j in the m-th terminal apparatus 2-m. As shown in (Equation 20), a channel estimation value (Equation 21) of the propagation path is calculated by performing a correlation operation between (Equation 19) and (Equation 18) generated inside the terminal device 2-m. .

  However, j = 1,..., Nr (m). K = 1,..., Ns. Furthermore, Nr (m) is the number of receiving unit antennas.

  Np is the number of symbols of the spatial stream dedicated pilot signal sequence. The superscript “*” is an operator that performs complex conjugate.

  In addition, the reception result of the spatial stream individual pilot signal sequence (Equation 18) over a plurality of times may be stored and an averaging process may be performed. In this case, if the moving speed of the terminal apparatus 2-m is sufficiently low, the influence of noise is reduced. The channel estimation quality of the propagation path can be improved.

Finally, as channel estimation values of the propagation path by the m-th terminal apparatus 2-m, a total of Ns × Nr (m) channel estimation values (Expression 21) are calculated. However, Ns is the number of spatially multiplexed streams, and Nr (m) is the number of receiving unit antennas of the terminal device 2-m.

  Here, a channel estimation matrix (Equation 22) for the terminal device 2-m is defined as (Equation 23).

  Next, separation of spatially multiplexed channels is performed using the obtained channel estimation matrix (Equation 22). Here, the separation of spatially multiplexed channels means the same operation as separating and extracting data signals included in each spatial stream from the spatially multiplexed stream.

  As a separation method, a case where ZF (Zero Forcing), which is a method using an inverse matrix of a channel estimation matrix, and a case where MMSE (Minimum Mean Square Error) is used will be described.

First, the case where the ZF method is used will be described. In the ZF technique, when the ZF technique is used for the received signal (Equation 24) at the j-th receiving unit antenna 20-j and the receiving unit 221-j in the m-th terminal apparatus 2- ^m , A row vector V (Bm) composed of the (Bm) -th row in (H ^m ) ⁻¹ which is an inverse matrix is calculated and used as a reception weight for receiving a desired spatial multiplexed stream.

  However, j = 1,..., Nr (m). Nr (m) is the number of receiving unit antennas.

  Here, Bm is a spatial stream number addressed to the terminal apparatus 2-m notified from the radio base station apparatus 1. As shown in (Equation 25), the data signal of the Bmth spatial stream number is multiplied by the reception weight V (Bm) by the spatial stream reception signal (Equation 26) in the terminal device 2-m, thereby obtaining another spatial stream. Can be extracted as a desired signal with suppressed interference signals.

Here, r ^(m) (t) is r _j ^(m) (t) received by the j-th antenna and receiving unit 221-j in the m-th terminal apparatus 2-m (where j = 1,..., Nr (m)) is a column vector having the jth element.

  Next, a case where the MMSE method is used will be described. Also in this case, similarly to the ZF method, a row vector V (Bm) composed of the Bmth row of the reception weight matrix W calculated according to the MMSE standard is calculated, and this is set as a reception weight for receiving a desired spatial stream.

  As shown in (Equation 25), the Bm-th spatial stream is obtained by multiplying the spatial stream reception signal (Equation 26) in the terminal device 2-m by the reception weight to suppress the interference signal components from other spatial streams. It can be received as a signal.

  When there are a plurality of spatial stream numbers addressed to the same terminal device 2-m, a reception weight for receiving the data signal of each spatial stream number is generated and multiplied by the spatial stream reception signal (Equation 26). Similarly, the desired signal can be separately received from the spatial stream.

  In addition, when information regarding the coding rate of the spatial stream data addressed to other than the terminal device 2-m, the coding method such as the modulation multi-level number, and the modulation method is known, maximum likelihood estimation (joint estimation), sequential It is possible to apply a technique such as an interference canceller (V-BLAST or the like).

  The demodulating unit 224 restores a desired transmission data sequence by performing demodulation and decoding processing on a desired signal separated and received from the spatial multiplexing stream.

  2B, since the terminal device 2-B having only a single receiving unit antenna 20-1 does not have the spatial demultiplexing unit 223 and cannot perform spatial interference removal, The demodulation unit 224 performs demodulation processing while compensating for the influence of the change in the environmental state of the propagation path using the channel estimation value obtained by the channel estimation unit 222 from the signal received by the reception unit 221-1.

  Through the operation as described above, in the embodiment of the present invention, according to various spatial correlation situations, spatial multiplexing transmission to a plurality of terminal devices 2-1 to 2-s, and further terminal devices 2-1 to 2-s. It is possible to select a transmission weight that can improve reception quality when receiving multiple antennas in s. As a result, it is possible to improve the system capacity by spatial multiplexing.

Furthermore, in the assignment work of the priority connection terminal apparatus 2 to be spatially multiplexed, the combination assignment control of the terminal apparatus 2 based on the detection of the spatial correlation coefficient, which has been performed in the conventional radio base station apparatus, becomes unnecessary, and the normal packet Allocation work can be performed only by preferential user allocation processing by the scheduler. As a result, it is possible to simplify the scheduling process for the terminal device 2 to be spatially connected.

  When the terminal device 2 includes a plurality of reception unit antennas as in the terminal device 2-A, the wireless base station device 1 transmits a known pilot signal for each spatial stream, and transmits the received pilot signal. By performing channel estimation using these pilot signals at 220, the radio base station apparatus 1 can generate a transmission weight even when a channel estimation error or a propagation path environment change, that is, a channel change with time has occurred. Therefore, it is possible to reduce the deterioration of communication quality due to the influence thereof.

  Further, in the case of a TDD system, it is possible to use the channel estimation result in the uplink as the channel estimation value in the downlink using the property of “relativity of propagation path”. In this case, the deviation between the systems including the transmission / reception antenna and the radio frequency (RF) circuit in the transmission / reception system in the uplink and the transmission / reception system in the downlink needs to be sufficiently corrected in advance. However, in general, sufficient correction cannot be performed and errors between systems are often included. Therefore, by applying this method, it is possible to reduce deterioration of communication quality due to the influence even when errors between systems are included as described above.

  In the embodiment of the present invention, after the transmission weight is generated by the transmission weight generators 6-1 to 6-n, the beam selection unit 7 selects the transmission weight based on the predicted SINR. And the transmission weight may be determined based on the average value or the minimum value.

  In this case, in order to select a transmission weight generation method suitable for the spatial correlation state between terminals earlier than the conventional method, specifically, it is roughly divided into the spatial correlation coefficient versus communication quality characteristics of the three types of transmission weight generation methods. Utilizing the fact that there is a specific relationship, this characteristic is divided into a plurality of sections so that a method with the best communication quality is automatically selected in each section.

  That is, extracting channel information between the terminal device and a radio base station from a received signal from the terminal device, obtaining a spatial correlation coefficient between the terminal devices to be spatially multiplexed based on the channel information, In relation to the three types of transmission weight generation methods, a processing method for selecting a method with the best communication quality in each section is determined in advance, and this selection processing method and the step of obtaining the spatial correlation coefficient are obtained. A transmission weight can be easily selected by including a step of selecting a method with the best communication quality based on the spatial correlation coefficient.

  The embodiment of the present invention can be realized without distinction between single carrier transmission and multicarrier transmission. At the time of multicarrier transmission, this can be realized by calculating a channel estimation value for each subcarrier and performing separate reception of spatially multiplexed streams as in the operation in this embodiment for each subcarrier. Further, the present invention can be applied regardless of duplex systems such as TDD and FDD. Further, the present invention can be applied regardless of access methods such as TDMA, FDMA, and CDMA.

  As described above, according to the first embodiment of the present invention, based on channel information for a plurality of terminal devices 2-1 to 2-s to be subjected to spatial multiplexing transmission, the plurality of terminal devices 2-1 to 2-2. System with transmission weight determination unit 5 that varies the method of generating a transmission weight for performing spatial multiplexing transmission for -s, thereby improving and ensuring communication quality in various spatial correlation situations and accompanying spatial multiplexing transmission system The effect that the capacity can be improved is obtained.

In addition, the transmission weight generation method suitable for the spatial correlation status between terminals can be varied, and spatial multiplexing transmission robust to the spatial correlation status between terminals becomes possible, and the allocation processing based on the conventional spatial correlation coefficient can be performed. Simplification can be achieved. Thereby, the effect that the processing time for the simplification of the radio base station apparatus 1 and the spatial multiplexing transmission control can be shortened can be obtained.

  Further, the radio base station apparatus 1 transmits transmission beams to be transmitted to the terminal apparatuses 2-1 to 2-s based on channel information for the terminal apparatuses 2-1 to 2-s to be spatially multiplexed. A plurality of transmission weight generation units 6-1 to 6-n that generate transmission weight information used for forming by different algorithms, and any one of the plurality of transmission weight information generated by the algorithm A beam selection unit 7 that selects a transmission beam and a transmission beam forming unit 9 that forms a transmission beam using the selected transmission weight information as a transmission weight, and has a function of performing spatial multiplexing transmission. Under various spatial correlation conditions, the communication capacity can be improved and secured and the system capacity can be improved by the spatial multiplexing transmission.

  In addition, it is possible to select a transmission weight generation method suitable for the spatial correlation status between terminals, enabling robust spatial multiplexing transmission to the spatial correlation status between terminals, and the allocation processing based on the conventional spatial correlation coefficient. Simplification can be achieved. Thereby, the effect that the processing time for the simplification of the radio base station apparatus 1 and the spatial multiplexing transmission control can be shortened can be obtained.

  Further, if the transmission power determination unit 8 has a function of determining the transmission power of the spatially multiplexed signals for the plurality of terminal apparatuses 2-1 to 2-s based on the selected transmission weight information, At the time of spatial multiplexing transmission to the terminal devices 2-1 to 2-s, an optimal transmission weight is selected from a plurality of different transmission weight generation algorithms in accordance with various spatial correlation conditions detected by channel information. It is possible to control the signal power that is generated and transmitted with these transmission weights. As a result, it is possible to perform transmission with signal power that satisfies the desired communication quality, and transmission using excessive transmission power is not performed, so that co-channel interference can be reduced and system capacity can be improved.

  Further, if the beam selection unit 7 has a function of selecting transmission weight information to be used as a transmission weight based on information indicating the signal-to-interference noise power ratio in the terminal device 2, various spatial correlation situations can be obtained. Below, there is an effect that the system capacity can be improved by improving and securing the communication quality and accompanying spatial multiplexing transmission.

    In addition, the beam selection unit 7 uses the predicted reception weight that predicts the reception weight at the terminal device 2 when the terminal device 2 can receive signals by the plurality of reception unit antennas 20-1 to 20-m. If the configuration has a function of selecting a transmission weight, it is possible to improve and secure communication quality under various spatial correlation conditions and to improve the system capacity by spatial multiplexing transmission associated therewith.

  Moreover, if the predicted reception weight is configured to form a maximum ratio combined reception beam, the communication capacity can be improved and secured under various spatial correlation conditions, and the system capacity can be improved by the spatial multiplexing transmission associated therewith. can get.

  In addition, if the prediction reception weight is a left singular vector obtained by singular value decomposition of the channel estimation matrix, a transmission weight that maximizes the reception power can be determined while suppressing co-channel interference, and a variety of In the spatial correlation situation, the communication capacity can be improved and secured, and the system capacity can be improved by the spatial multiplexing transmission associated therewith.

Further, if the predicted reception weight has a weight configuration that forms a least-square error beam, the spatial reception status varies depending on the channel information in spatial multiplexing transmission to a plurality of terminal apparatuses 2-1 to 2-s. By predicting the reception quality when the terminal device 2 having a plurality of receiving unit antennas 20-1 to 20-m uses a left singular vector obtained by singular value decomposition of the channel estimation matrix as a corresponding transmission weight. The optimum one can be selected from those generated by a plurality of different transmission weight generation algorithms.

  As a result, among the left singular vectors obtained by singular value decomposition of the channel estimation matrix, in particular, by using the left singular vector corresponding to the one having the maximum singular value, the signal-to-noise power ratio (SNR) is maximized. The transmission weight information that can obtain the reception quality that maximizes the signal-to-noise power ratio can be selected from a plurality of transmission weight information groups by using the property that the reception quality to be obtained can be obtained.

  This is particularly effective when the spatial correlation between terminal devices connected simultaneously is low and there are few co-channel interference waves. In addition, the reception weight in the terminal device 2 can be uniquely determined from the channel estimation matrix. When the number of spatially multiplexed streams to the terminal device 2 is smaller than the number of reception unit antennas in the terminal device 2, a transmission weight is formed. Therefore, it is possible to select a transmission weight having a high transmission diversity effect that can relax the constraint condition for reducing the co-channel interference. As a result, the communication capacity can be improved and secured and the system capacity can be improved by the spatial multiplexing transmission associated therewith.

  Further, if the predicted reception weight is a weight configuration that forms a zero-forming beam, it corresponds to various spatial correlation conditions detected by channel information at the time of spatial multiplexing transmission to a plurality of terminal apparatuses 2-1 to 2-s. As a transmission weight, a terminal device 2 having a plurality of reception unit antennas 20-1 to 20-m predicts reception quality when a least square error (MMSE) beam is used, so that a plurality of different transmission weight generation algorithms are used. An optimum one can be selected from the generated ones.

  As a result, the terminal device 2 uses the weight that forms the least square error (MMSE) beam, and thus the reception quality that maximizes the signal-to-interference noise power ratio (SINR) can be obtained. From the group, it is possible to select transmission weight information capable of obtaining reception quality that maximizes the signal-to-interference noise power ratio, and to improve communication quality under various spatial correlation conditions in an environment where co-channel interference waves exist. The system capacity can be improved by securing and accompanying spatial multiplexing transmission.

  Further, if the transmission power determination unit 8 has a function of determining the transmission power of spatially multiplexed signals for the plurality of terminal apparatuses 2-1 to 2-s based on the selected transmission weight information, a plurality of terminals Terminal apparatus 2 having a plurality of receiving unit antennas 20-1 to 20-m as transmission weights according to various spatial correlation conditions detected by channel information at the time of spatial multiplexing transmission to apparatuses 2-1 to 2-s Predicting the reception quality when a zero forcing (ZF) beam is used, it is possible to select an optimum one from those generated by a plurality of different transmission weight generation algorithms.

  Furthermore, by using the weight that forms a zero forcing (ZF) beam, the terminal device 2 uses the property that the reception quality of the reception weight is obtained under the constraint that prioritizes suppression of the interference noise power of the same channel, From a plurality of transmission weight information groups, it is possible to select transmission weight information that provides a reception quality that maximizes the signal-to-interference noise power ratio. As a result, it is possible to determine the transmission weight that maximizes the received power while suppressing co-channel interference, and the effect of improving and securing communication quality under various spatial correlation conditions and improving the system capacity by spatial multiplexing transmission associated therewith Is obtained. In addition, since the ZF beam can be calculated with a smaller amount of computation than the MMSE beam, the circuit scale can be reduced and the cost of the apparatus can be reduced.

Also, the radio base station apparatus 1 uses the plurality of terminal apparatuses 2-1 based on channel information for the plurality of terminal apparatuses 2-1 to 2-s having one or more receiving unit antennas to be spatially multiplexed. A plurality of transmission weight generation units 6-1 to 6-n that generate transmission weight information groups for performing spatial multiplexing transmission for ~ 2-s using different algorithms;
Based on the channel information, the beam selection unit 7 selects a transmission weight generation unit 6 having a specific algorithm in advance, and a function of performing spatial multiplexing transmission using the selected transmission weight information as a transmission weight. For example, the system capacity can be improved by improving and securing the communication quality and accompanying spatial multiplexing transmission under various spatial correlation conditions.

  In addition, if one transmission weight generation unit 6 among the plurality of transmission weight generation units 6-1 to 6-n has a function of generating transmission weight information for forming an eigenvector beam for the terminal device 2, a plurality of transmission weight generation units 6-1 to 6-n To the other terminal apparatus 2 when the channel correlation between the terminal apparatuses is low, especially in accordance with various spatial correlation conditions detected by the channel information during spatial multiplexing transmission to the terminal apparatuses 2-1 to 2-s. The effect that the transmission weight which improves reception quality to the desired terminal device 2 can be used without adding the constraint condition for reducing the interference is obtained.

  In addition, one of the plurality of transmission weight generation units 6-1 to 6-n transmits one piece of transmission weight information that does not reduce or give interference to a terminal device 2 other than the desired terminal device 2. If the configuration has a function to generate, in the spatial multiplexing transmission to a plurality of terminal devices 2-1 to 2-s, in particular, according to various spatial correlation situations detected by channel information, In the case where the correlation is relatively high, it is possible to use a transmission weight that enhances the reception quality to the desired terminal device 2 after adding a constraint condition that minimizes the interference to the other terminal device 2. It is done.

  Further, one transmission weight generation unit 6 among the plurality of transmission weight generation units 6-1 to 6-n assumes that the desired terminal device 2 receives the maximum ratio combining reception, and a terminal other than the desired terminal device 2 If the apparatus has a function of generating transmission weight information that does not reduce or give interference to the apparatus 2, it is detected by channel information at the time of spatial multiplexing transmission to a plurality of terminal apparatuses 2-1 to 2-s. According to various spatial correlation situations, especially when the correlation between channels between terminal devices is relatively high and the other terminal device 2 has a plurality of receiving unit antennas 20-1 to 20-m, the device other than the desired terminal device 2 is used. The number of constraint conditions that minimizes interference with the other terminal devices 2 can be reduced and added. Thereby, the effect that the transmission weight which improves the reception quality to the desired terminal device 2 can be used is acquired.

  In addition, one transmission weight generation unit 6 among the plurality of transmission weight generation units 6-1 to 6-n has a function of generating transmission weight information that forms a transmission weight vector in which all components are zero. Then, in the case of spatial multiplexing transmission to a plurality of terminal apparatuses 2-1 to 2-s, in particular, when the channel correlation between the terminal apparatuses is high according to various spatial correlation conditions detected by the channel information. The effect that the transmission weight which does not transmit to the terminal device 2 can be used is acquired.

  If one transmission weight generation unit 6 among the plurality of transmission weight generation units 6-1 to 6-n has a function of generating transmission weight information for forming a fixed transmission weight vector in advance, a plurality of transmission weight generation units 6 to 6-n can be used. At the time of spatial multiplexing transmission to the terminal devices 2-1 to 2-s, it is possible to selectively vary a predetermined fixed transmission weight suitable for various spatial correlation conditions detected by channel information. As a result, it is possible to improve the system quality by improving and securing the communication quality and the accompanying spatial multiplexing transmission under various spatial correlation conditions.

Further, the radio base station apparatus 1 has a function of performing spatial multiplexing transmission by inserting a known signal sequence in advance for each signal to be spatially multiplexed transmitted using a transmission weight vector formed from selected transmission weight information data. With this configuration, it is possible to change to a transmission weight generation method suitable for various spatial correlation conditions detected by channel information at the time of spatial multiplexing transmission to a plurality of terminal apparatuses 2-1 to 2-s. Even when an error is included in the signal, the terminal apparatus can separate and receive the spatially multiplexed signal using a known signal sequence for each transmission signal. As a result, it is possible to improve the system quality by improving and securing the communication quality and the accompanying spatial multiplexing transmission under various spatial correlation conditions.

  Also, the terminal device 2 performs channel estimation based on a known signal sequence assigned to each spatially multiplexed signal, and generates a reception weight for separating and outputting a desired signal from the spatially multiplexed signal. In the spatial multiplexing transmission to the plurality of terminal apparatuses 2-1 to 2-s, the terminal apparatus 2 side uses a known signal sequence for each transmission signal to convert the spatially multiplexed signal. Separate reception is possible.

  Thereby, in particular, when transmission weight generation is performed based on channel information including an error on the radio base station apparatus 1 side, spatial multiplexing is performed using a known signal sequence for each transmission signal on the terminal apparatus 2 side. Signals can be separated and received, and the effect of improving and securing communication quality under various spatial correlation conditions and improving the system capacity by spatial multiplexing transmission associated therewith can be obtained.

  Further, the channel estimation unit 222 and the spatial demultiplexing unit 223 have a function of generating a maximum ratio combined weight as a reception weight based on a value obtained as a result of channel estimation in the channel estimation unit 222. At the time of spatial multiplexing transmission to the plurality of terminal apparatuses 2-1 to 2-s, the terminal apparatus 2 side can separately receive the spatially multiplexed signals using a known signal sequence for each transmission signal.

  Thereby, in particular, when transmission weight generation is performed based on channel information including an error on the radio base station apparatus 1 side, spatial multiplexing is performed using a known signal sequence for each transmission signal on the terminal apparatus 2 side. Signals can be separately received so as to maximize received power, and the effect of improving and securing communication quality under various spatial correlation conditions and improving the system capacity by spatial multiplexing transmission associated therewith can be obtained.

  In addition, the channel estimation unit 222 and the spatial demultiplexing unit 223 have a function of generating a least square error weight as a reception weight based on a value obtained as a result of channel estimation in the channel estimation unit 222. At the time of spatial multiplexing transmission to the plurality of terminal apparatuses 2-1 to 2-s, the terminal apparatus 2 side can separately receive the spatially multiplexed signals using a known signal sequence for each transmission signal.

  Thereby, in particular, when transmission weight generation is performed based on channel information including an error on the radio base station apparatus 1 side, spatial multiplexing is performed using a known signal sequence for each transmission signal on the terminal apparatus 2 side. Signals can be received separately so that desired received power vs. interference noise power is maximized, and the communication capacity can be improved and secured under various spatial correlation conditions, and the system capacity can be improved by spatial multiplexing transmission associated therewith. Is obtained.

  The channel estimation unit 222 and the spatial demultiplexing unit 223 perform channel estimation based on a known signal sequence inserted for each spatially multiplexed signal, and singular value decomposition of the obtained channel estimation matrix If the left singular vector corresponding to the maximum singular value obtained as described above is configured to have a function of generating a reception weight for separating and outputting a desired signal from the spatially multiplexed signal, a plurality of terminal devices 2-1 to 2-1 At the time of spatial multiplexing transmission for 2-s, the terminal apparatus 2 side can separately receive a spatially multiplexed signal using a known signal sequence for each transmission antenna.

  As a result, in particular, when a transmission weight that enhances reception quality to a desired terminal device 2 is used after adding a constraint that minimizes interference with the other terminal device 2, the same channel for the other terminal device 2 is used. It is possible to suppress the interference wave and maximize the received power of the spatially multiplexed signal component, thereby obtaining the effect of improving and securing the communication quality and improving the system capacity by the spatial multiplexing transmission associated therewith.

Also, the wireless communication method of the present invention extracts channel information between the terminal device 2 and the wireless base station device 1 from a received signal from the terminal device 2, and performs spatial multiplexing transmission based on the extracted channel information. A transmission weight that increases the reception quality to a desired terminal device after adding a step of obtaining a spatial correlation coefficient between a plurality of terminal devices and a constraint that minimizes interference with the other terminal devices 2 A first method of generating a transmission weight using an algorithm to generate;
A second method using an algorithm for generating a transmission weight that improves the reception quality to the desired terminal apparatus 2 without adding a constraint condition of reducing the interference to the other terminal apparatus 2, and a single transmission weight From the third method for generating the transmission weight using the algorithm to be generated, based on a predetermined selection processing method, a method with the best communication quality according to the spatial correlation coefficient obtained in the above step By using the fact that there is a specific relationship between the spatial correlation coefficient versus the communication quality characteristic of three different transmission weight generation methods, the characteristic is divided into a plurality of sections in advance. Thus, the method selection processing method can be set so that the method with the best communication quality is selected in each section. It is not necessary to carry out the formula selected, it is possible to select a transmission weight generation method suitable for the spatial correlation conditions between the terminal device, robust spatial multiplexing transmission can be performed with respect to spatial correlation conditions between terminals. As a result, it is possible to simplify the assignment process of terminal devices to be spatially multiplexed, reduce the processing time, and improve the system capacity by spatial multiplexing transmission.

(Embodiment 2)
A radio base station apparatus 100 according to the second embodiment of the present invention is shown in FIG. In the block diagram, the difference from the radio base station apparatus 1 according to the first embodiment is that the selection switch unit 107-a is used instead of the beam selection unit 7, and the channel information acquisition unit 4 and the transmission weight generation unit 6- The selection switch unit 107-b is inserted between 1 to 6-n. From the viewpoint of the function, the channel information acquisition unit 4 selects the optimum transmission weight generation unit 6 based on the extracted channel information in addition to the channel information extraction operation which is a conventional function. This has a function of controlling the selection switch section.

  On the other hand, the selection switch units 107-a and 107-b are linked, and when the selection switch unit 107-b selects, for example, the transmission weight generation unit 6-1, the selection switch unit 107-a becomes the transmission weight generation unit. Connect to the output side of 6-1. The selection switch unit 107-b is also linked to the operation switch of the transmission weight generation unit, and the connected transmission weight generation unit 6 is turned on and channel information is input. With this operation, channel information is extracted, and an optimal transmission weight generation unit is selected and operated, and transmission weight information as an output thereof is obtained.

  As a result, only the selected transmission weight generation unit 6 is operated, so that in addition to the effect of the first embodiment of the present invention, power consumption in the radio base station apparatus 100 can be reduced. Further, when the transmission weight calculation in the transmission weight generation unit 6 is calculated using a common CPU, only the selected transmission weight generation unit 6 occupies the CPU. Can be planned. As a result, the throughput of the total system can be improved.

  As described above, in the second embodiment of the present invention, based on channel information for a plurality of terminal devices 2-1 to 2-s to be spatially multiplexed, the plurality of terminal devices 2-1 to 2- Select switch units 107-a and 107-b for selecting an arbitrary transmission weight generation unit 6 from a plurality of transmission weight generation units 6-1 to 6-n that generate transmission weights for performing spatial multiplexing transmission for s are transmitted. With the configuration of the weight generation units 6-1 to 6-n at both ends, it is possible to obtain an effect that improvement and securing of communication quality and improvement of system capacity by spatial multiplexing transmission can be achieved under various spatial correlation conditions.

  In addition, a transmission weight generation method suitable for the spatial correlation status between terminals can be selected in advance, and spatial multiplexing transmission that is robust to the spatial correlation status between terminals is possible, and the conventional allocation process based on the spatial correlation coefficient Can be simplified. Furthermore, the power consumption in the radio base station apparatus 100 can be reduced, and the calculation processing capability can be improved. As a result, the effect of improving the throughput of the system as a whole can be obtained. This also has the effect of simplifying the radio base station apparatus 100 and shortening the processing time for spatial multiplexing transmission control.

  Further, if the transmission power determination unit 8 has a function of determining the transmission power of the spatially multiplexed signals for the plurality of terminal apparatuses 2-1 to 2-s based on the selected transmission weight information, At the time of spatial multiplexing transmission to the terminal devices 2-1 to 2-s, an optimal transmission weight is selected from a plurality of different transmission weight generation algorithms in accordance with various spatial correlation conditions detected by channel information. It is possible to control the signal power that is generated and transmitted with these transmission weights.

  As a result, it is possible to perform transmission with signal power that satisfies the desired communication quality, and transmission using excessive transmission power is not performed, so that co-channel interference can be reduced and system capacity can be improved.

  In addition, one of the plurality of transmission weight generation units 6-1 to 6-n has a function of generating transmission weight information for forming eigenvector beams for the terminal devices 2-1 to 2-s. According to the configuration, during spatial multiplexing transmission to a plurality of terminal apparatuses 2-1 to 2-s, particularly when the channel correlation between the terminal apparatuses is low according to various spatial correlation situations detected by the channel information. Thus, there is an effect that it is possible to use a transmission weight that enhances reception quality to the desired terminal apparatus 2 without adding a constraint condition for reducing interference with the other terminal apparatus 2.

  In addition, one of the plurality of transmission weight generation units 6-1 to 6-n transmits one piece of transmission weight information that does not reduce or give interference to a terminal device 2 other than the desired terminal device 2. If the configuration has a function to generate, in the spatial multiplexing transmission to a plurality of terminal devices 2-1 to 2-s, in particular, according to various spatial correlation situations detected by channel information, In the case where the correlation is relatively high, it is possible to use a transmission weight that enhances the reception quality to the desired terminal device 2 after adding a constraint condition that minimizes the interference to the other terminal device 2. It is done.

Further, one transmission weight generation unit 6 among the plurality of transmission weight generation units 6-1 to 6-n assumes that the desired terminal device 2 receives the maximum ratio combining reception, and a terminal other than the desired terminal device 2 If the apparatus has a function of generating transmission weight information that does not reduce or give interference to the apparatus 2, it is detected by channel information at the time of spatial multiplexing transmission to a plurality of terminal apparatuses 2-1 to 2-s. According to various spatial correlation situations, especially when the correlation between channels between terminal devices is relatively high and the other terminal device 2 has a plurality of receiving unit antennas 20-1 to 20-m, the device other than the desired terminal device 2 is used. The number of constraint conditions that minimizes interference with the other terminal devices 2 can be reduced and added. Thereby, the effect that the transmission weight which improves the reception quality to the desired terminal device 2 can be used is acquired.

  In addition, one transmission weight generation unit 6 among the plurality of transmission weight generation units 6-1 to 6-n has a function of generating transmission weight information that forms a transmission weight vector in which all components are zero. Then, in the case of spatial multiplexing transmission to a plurality of terminal apparatuses 2-1 to 2-s, in particular, when the channel correlation between the terminal apparatuses is high according to various spatial correlation conditions detected by the channel information. The effect that the transmission weight which does not transmit to the terminal device 2 can be used is acquired.

  If one transmission weight generation unit 6 among the plurality of transmission weight generation units 6-1 to 6-n has a function of generating transmission weight information for forming a fixed transmission weight vector in advance, a plurality of transmission weight generation units 6 to 6-n can be used. At the time of spatial multiplexing transmission to the terminal devices 2-1 to 2-s, it is possible to selectively vary a predetermined fixed transmission weight suitable for various spatial correlation conditions detected by channel information. As a result, it is possible to improve the system quality by improving and securing the communication quality and the accompanying spatial multiplexing transmission under various spatial correlation conditions.

  Radio base station apparatus 100 has a function of inserting a known signal sequence in advance and performing spatial multiplexing transmission for each signal that is spatially multiplexed transmitted using a transmission weight vector formed from selected transmission weight information data. With this configuration, it is possible to change to a transmission weight generation method suitable for various spatial correlation conditions detected by channel information at the time of spatial multiplexing transmission to a plurality of terminal apparatuses 2-1 to 2-s. Even when an error is included in the signal, the terminal apparatus can separate and receive the spatially multiplexed signal using a known signal sequence for each transmission signal. As a result, it is possible to improve the system quality by improving and securing the communication quality and the accompanying spatial multiplexing transmission under various spatial correlation conditions.

(Embodiment 3)
FIG. 12 shows a radio base station apparatus 1-A according to the third embodiment of the present invention, and FIG. 13 shows a terminal apparatus 2-C. In the block diagram, the radio base station apparatus 1-A according to the present embodiment is different from the radio base station apparatus 1 according to the first embodiment in that the spatial demultiplexing technique information transmitted from the terminal apparatus 2-C is used. This further includes a separation algorithm acquisition unit 400 to be acquired, and a beam selection unit 401 that selects one of the outputs of the transmission weight generation units 6-1 to 6-n based on the spatial demultiplexing method information. The terminal device 2-C according to the present embodiment is different from the terminal device 2-A according to the first embodiment in that the spatial multiplexing / demultiplexing in the spatial multiplexing / demultiplexing unit 223 used by the terminal device 2-C during reception is performed. A spatial demultiplexing technique storage unit 300 that stores the technique, and a transmission unit 212-A that performs appropriate data processing on the spatial demultiplexing technique information 301 that is output information and converts the information into a high frequency signal. It is a point. In the following, operations different from those of the first embodiment in the components added and changed as described above will be mainly described.

  In FIG. 13, a terminal apparatus 2-C according to the embodiment of the present invention having a plurality of antennas includes a transmission unit 210, a transmission unit antenna 216, a reception unit 220, and reception unit antennas 20-1 to 20-m. ing.

The transmission unit 210 stores the channel estimation information transmitted from the data input unit 214 and the channel estimation unit 222 to which data information to be transmitted by the terminal user is input, and the spatial demultiplexing method of the spatial demultiplexing unit 223. A transmission unit 212-A that performs appropriate data processing on the spatial demultiplexing method information 301, which is output information from the spatial demultiplexing method storage unit 300, and converts the information into a high-frequency signal. Spatial demultiplexing methods include MMSE, ZF, MLD (Maximum Likelihood Detection), SI
C (Successive (or Serial) -Interference-Can
It includes information on algorithms used in spatial demultiplexing such as celler (sequential interference canceller) and PIC (Parallel-Interference-Canceller). Moreover, the information amount at the time of transmission can be reduced by transmitting the provided classification number using the table previously categorized. Alternatively, a table that is ranked by a performance index indicating the performance of the separation method may be used. For example, MMSE, ZF, etc. are ranked as class 1, SIC, PIC, etc. as class 2, MLD, etc. as class 3, and the associated table is used.

  The reception unit 220 corresponds to each of the reception unit antennas 20-1 to 20-m, and receives units 221-1 to 221 that convert high-frequency signals received by the reception antennas 20-1 to 20-m into baseband signals. -M, a channel estimation unit 222 that estimates channel response information of a channel in the downlink from a plurality of baseband signals, and a desired signal is separated from the spatial multiplexing signal based on the channel response information obtained by the channel estimation unit 222 A spatial multiplexing / demultiplexing unit 223 to extract, a demodulating unit 224 that restores a transmission data sequence from a desired signal that has been separated and received, and outputs the restored reception data sequence to another device, or a terminal device user And a data output unit 225 for transmitting the information.

  Here, although the transmission unit antenna 216 and the reception unit antennas 20-1 to 20-m are treated as different ones, they may share the same antenna.

  Next, operations of the radio base station apparatus 1-A and the terminal apparatus 2-C will be described. First, on the assumption that the downlink channel information is estimated in the terminal devices 2-1 to 2-s, the operation of notifying this information to the radio base station device 1-A will be outlined.

  First, in the transmission unit 210 of the terminal device 2-C, channel information of a propagation path (not shown) estimated by the channel estimation unit 222 is guided to the transmission unit 212, and the control unit or the broadcast channel is transmitted by the transmission unit 212. Is transmitted to the radio base station apparatus 1 via. That is, the control channel signal or broadcast channel signal carrying the channel information is guided to the transmission unit antenna 216 and emitted from the transmission unit antenna 216 to the propagation path (not shown) toward the radio base station apparatus 1-A. Is done.

  Here, the control channel or the broadcast channel is a communication channel for exchanging information for effectively operating the radio base station apparatus 1-A and the terminal apparatus 2-C. This is a communication channel different from the communication channel through which information to be transmitted / received by a person is exchanged.

  Information to be transmitted by the user of the terminal device 2-C is input from the data input unit 214 to the transmission unit 212, subjected to appropriate signal processing, converted into a high-frequency signal, and then transmitted to the transmission unit antenna 216. Via the wireless base station apparatus 1-A.

  Thereafter, in the radio base station apparatus 1-A, the channel information acquisition unit 4 changes from the plurality of terminal apparatuses 2-1 to 2-s having the configuration of the terminal apparatus 2-C to the base station antennas 11-1 to 11-s. The channel information transmitted from each of the terminal devices 2-1 to 2 -s is extracted from the control channel signal or the broadcast channel signal transmitted to the terminal, and is output to the transmission weight determination unit 5.

  Next, based on the notified downlink channel information and spatial multiplexing / demultiplexing method information, an appropriate transmission weight is applied to transmission signals addressed to (assigned) terminal apparatuses 2-1 to 2-s to be spatially multiplexed. The operation in which spatial multiplexing transmission is performed by multiplication will be outlined.

  First, in the radio base station apparatus 1-A, the channel information acquisition unit 4 is directed from the terminal apparatuses 2-1 to 2-s to be spatially multiplexed (assigned) to the base station antennas 11-1 to 11-s. The channel information transmitted from each of the terminal devices 2-1 to 2 -s is extracted from the control channel signal or broadcast channel signal transmitted in this manner, and is output to the transmission weight determining unit 5. The channel information extracted at this time is downlink channel information from the radio base station apparatus 1-A to the terminal apparatuses 2-1 to 2-s. In addition, the separation algorithm information acquisition unit 400 transmits control channel signals transmitted from the terminal devices 2-1 to 2-s that should be spatially multiplexed (assigned) to the base station antennas 11-1 to 11-s. Alternatively, the spatial multiplexing / demultiplexing method information transmitted from each terminal device 2-1 to 2-s is extracted from the broadcast channel signal and output to the transmission weight determining unit 5.

  Next, the transmission weight determination unit 5 transmits different transmission weights to the terminal devices 2-1 to 2-s to be spatially multiplexed in order to perform optimal signal transmission according to the correlation state between the terminal devices. A plurality of types of transmission weight generation information are generated by a plurality of transmission weight generation units 6-1 to 6-n having a generation algorithm. Thereafter, the beam selection unit 401 maximizes a predetermined criterion from among a plurality of transmission weight generation information groups generated by the first to nth transmission weight generation units 6-1 to 6-n. The transmission weight information is selected, and this information is output to the transmission power determination unit 8 and the transmission beam forming unit 9.

  Next, the transmission power determination unit 8 calculates a power distribution coefficient for determining transmission power for each spatial multiplexing stream, based on the input transmission weight information.

  On the other hand, the transmission signal generation units 3-1 to 3-s generate signals (hereinafter referred to as transmission data sequences) addressed to the terminal devices 2-1 to 2-s to be spatially multiplexed (priority assigned), respectively. Output after appropriate signal processing.

  Then, in the power coefficient multipliers 10-1 to 10-s, the signal output of each of the transmission signal generation units 3-1 to 3-s is multiplied by the power distribution coefficient calculated by the transmission power determination unit 8. Next, the transmission beam forming unit 9 applies a predetermined (selected) beam to each transmission data frame sequence signal multiplied by the power distribution coefficient based on the transmission weight information from the beam selection unit 401. Baseband symbol data multiplied by the transmission weight to be formed is generated. After that, digital data, which is baseband symbol data, is digital / analog converted by a digital / analog converter (not shown), a band limiting filter and a frequency converter, further band-limited, and then converted to a carrier frequency. Outputs high frequency signals. The radio base station antennas 11-1 to 11-s emit the supplied high-frequency signals to a propagation path (space) (not shown) toward the terminal devices 2-1 to 2-s to be spatially multiplexed.

  Here, the operation of the reception processing in the terminal apparatuses 2-1 to 2-s for the signals that are spatially multiplexed and transmitted in the radio base station apparatus 1 is the same as that in the first embodiment, and thus the description thereof is omitted.

  Regarding the above detailed operation, [1] the transmission weight generation algorithm incorporated in the transmission weight generation units 6-1 to 6-n and [3] the method of determining the transmission power distribution coefficient are the same as those in the first embodiment. Detailed description is omitted. In the following, a detailed description will be given of a transmission weight information selection method in [2] beam selection section 401 which is an operation different from that of the first embodiment.

[2] Detailed Description of Transmission Weight Information Selection Method in Beam Selection Unit 401 Here, a detailed description is given of the transmission weight information selection method in the beam selection unit 401. The beam selection unit 401 selects transmission weight information that maximizes a predetermined criterion from among a plurality of transmission weight information groups generated by the first to nth transmission weight generation units 6-1 to 6-n. select. As a determination criterion, a prediction value of a physical quantity indicating signal quality such as a signal-to-noise power ratio (SNR) or a signal-to-interference wave power ratio (SINR) received by the terminal device 2-C is obtained from the separation algorithm information acquisition unit 400. Based on the output of. This point is different from the beam selection unit 7 in the first embodiment.

  That is, in Embodiment 1, when the number of antennas of terminal apparatus 2-k is plural, SINR evaluation is performed using (Equation 16) assuming directivity formation by reception weight R (k). In the present embodiment, the channel information H (k) for the k-th terminal apparatus 2-k is obtained based on the spatial demultiplexing technique information of the terminal apparatus 2-k that is an output from the separation algorithm information acquisition unit 400. To generate a reception weight R (k). Here, the reception weight R (k) represents a row vector having Nr (k) elements for the number of reception unit antennas of the terminal device 2-k. In (Expression 16), the subscript “n” indicates the number when the user terminal, that is, each terminal device 2 that performs spatial multiplexing connection is numbered in order, and in this embodiment, the terminal device 2-1. Corresponds to ~ 2-s. As the spatial multiplexing / demultiplexing method information, when there is an interference wave component, the MMSE method, the ZF method, and the eigenvector beam reception method can be applied. The ratio combining reception weight is included.

  As described above, SINRn (k) of each user is calculated using Wn (k) shown in (Equation 16) as a variable. This is all calculated for the outputs of the first to nth transmission weight generation units. Then, a transmission weight Ws (k) that is output information from the sth transmission weight generation unit 6-s that generates a transmission weight that maximizes the sum of the SINRn (k) of each user is selected. Here, k = 1 to Ns.

  As described above, in Embodiment 3 of the present invention, the predicted SINR evaluation is performed by using the spatial demultiplexing technique information transmitted from the terminal apparatus. As a result, the predicted SINR evaluation value can be made closer to the SINR received by the actual terminal device. Therefore, since the transmission weight can be selected using such a predicted SINR, a more optimal transmission weight can be selected, the communication quality of the terminal device 2 that performs communication can be improved, and the capacity of the communication system can be increased. Can be increased.

  In addition, since the predicted SINR is also used when calculating the transmission power distribution coefficient, more optimal power distribution is performed due to the effect that the predicted SINR evaluation value can be made closer to the SINR received by the actual terminal device. be able to. Since the communication quality of the terminal device 2 that performs communication by such transmission power control can be ensured at a necessary and sufficient level and the transmission power is not increased more than necessary, the present embodiment is applied to the cellular system. In this case, inter-cell interference can be reduced, and the capacity of the communication system can be increased.

(Embodiment 4)
FIG. 14 shows a radio base station apparatus 1-B and FIG. 15 shows a terminal apparatus 2-D according to the fourth embodiment of the present invention. In the block diagram, the difference from the radio base station apparatus 1 of the first embodiment is that it further includes an other cell interference information acquisition unit 410 that acquires other cell interference information transmitted from the terminal apparatus 2-D. The beam selection unit 411 selects one of the outputs of the transmission weight generation units 6-1 to 6-n based on the acquired other cell interference information.

  Further, the difference from the terminal device 2-A of the first embodiment is that the terminal device 2-D measures the interference state from other cells received at the time of reception, and its output information. The other cell interference information 310 is subjected to appropriate data processing and is provided with a transmission unit 212-B that converts it into a high-frequency signal. Hereinafter, operations different from those of the first embodiment in the components added and changed will be mainly described.

  In FIG. 15, a terminal apparatus 2-D according to the embodiment of the present invention having a plurality of antennas includes a transmission unit 210, a transmission unit antenna 216, a reception unit 220, and reception unit antennas 20-1 to 20-m. ing.

  The transmission unit 210 includes a data input unit 214 to which data information to be transmitted by the terminal user is input, channel estimation information transmitted from the channel estimation unit 222, and another cell output from the other cell interference detection unit 302. A transmission unit 212-B that performs appropriate data processing on the interference information and converts the interference information into a high-frequency signal;

  The reception unit 220 corresponds to each of the reception unit antennas 20-1 to 20-m, and receives units 221-1 to 221 that convert high-frequency signals received by the reception antennas 20-1 to 20-m into baseband signals. -M, a channel estimation unit 222 that estimates channel response information of a channel in the downlink from a plurality of baseband signals, and a desired signal is separated from the spatial multiplexing signal based on the channel response information obtained by the channel estimation unit 222 A spatial multiplexing / demultiplexing unit 223 to extract, a demodulating unit 224 that restores a transmission data sequence from a desired signal that has been separated and received, and outputs the restored reception data sequence to another device, or a terminal device user And a data output unit 225 for transmitting the information.

  Here, although the transmission unit antenna 216 and the reception unit antennas 20-1 to 20-m are treated as different ones, they may share the same antenna.

  Next, operations of the radio base station apparatus 1-B and the terminal apparatus 2-D will be described. First, on the assumption that the downlink channel information is estimated by the terminal apparatuses 2-1 to 2-s, the operation of notifying the downlink channel information to the radio base station apparatus 1-B is outlined. To do.

  First, in the transmission unit 210 of the terminal device 2-D, channel information of a propagation path (not shown) estimated by the channel estimation unit 222 is guided to the transmission unit 212, and the control unit or the broadcast channel is transmitted by the transmission unit 212. Is transmitted to the radio base station apparatus 1-B. That is, the control channel signal or broadcast channel signal carrying the channel information is guided to the transmission unit antenna 216, and is directed from the transmission unit antenna 216 to a propagation path (not shown) toward the radio base station apparatus 1-B. Released.

  Here, the control channel or the broadcast channel is a communication channel for exchanging information for effectively operating the radio base station apparatus 1-B and the terminal apparatus 2-D. The communication channel is different from the communication channel for exchanging information to be transmitted / received by the user.

  Information to be transmitted by the user of the terminal device 2-D is input from the data input unit 214 to the transmission unit 212, subjected to appropriate signal processing, converted into a high-frequency signal, and then transmitted to the transmission unit antenna 216. Via the wireless base station apparatus 1-B.

  Thereafter, in the radio base station apparatus 1-B, the channel information acquisition unit 4 moves from the plurality of terminal apparatuses 2-1 to 2-s having the configuration of the terminal apparatus 2-D to the base station antennas 11-1 to 11-s. The channel information transmitted from each of the terminal devices 2-1 to 2 -s is extracted from the control channel signal or the broadcast channel signal transmitted to the terminal, and is output to the transmission weight determination unit 5.

Next, based on the notified downlink channel information and spatial demultiplexing technique information, the terminal devices 2-1 to 2-s to be spatially multiplexed, that is, the allocated terminal devices 2-1 to 2-
An operation of performing spatial multiplexing transmission by multiplying a transmission signal addressed to s by an appropriate transmission weight will be outlined.

  First, in the radio base station apparatus 1-B, the channel information acquisition unit 4 is transmitted from the terminal apparatuses 2-1 to 2-s to be spatially multiplexed to the base station antennas 11-1 to 11-s. From the control channel signal or the broadcast channel signal, channel information transmitted from each of the terminal devices 2-1 to 2-s is extracted and output to the transmission weight determining unit 5. The channel information extracted at this time is downlink channel information from the radio base station apparatus 1-B to the terminal apparatuses 2-1 to 2-s. In addition, the other-cell interference information acquisition unit 410 transmits a control channel transmitted from the terminal apparatuses 2-1 to 2-s that should be spatially connected (assigned) to the base station antennas 11-1 to 11-s. The other cell interference information transmitted from each of the terminal devices 2-1 to 2 -s is extracted from the signal or the broadcast channel signal, and is output to the transmission weight determination unit 5.

  Next, the transmission weight determination unit 5 transmits different transmission weights to the terminal devices 2-1 to 2-s to be spatially multiplexed in order to perform optimal signal transmission according to the correlation state between the terminal devices. A plurality of types of transmission weight generation information are generated by a plurality of transmission weight generation units 6-1 to 6-n having a generation algorithm.

  Thereafter, the beam selection unit 411 maximizes a predetermined criterion from among a plurality of transmission weight generation information groups generated by the first to nth transmission weight generation units 6-1 to 6-n. The transmission weight information is selected, and the selected transmission weight information is output to the transmission power determination unit 8 and the transmission beam forming unit 9.

  Next, the transmission power determination unit 8 calculates a power distribution coefficient for determining transmission power for each spatial multiplexing stream, based on the input transmission weight information.

  On the other hand, the transmission signal generation units 3-1 to 3-s generate signals (hereinafter referred to as transmission data sequences) addressed to the terminal devices 2-1 to 2-s to be spatially multiplexed (priority assigned), respectively. Output after appropriate signal processing.

  Then, in the power coefficient multipliers 10-1 to 10-s, the signal output of each of the transmission signal generation units 3-1 to 3-s is multiplied by the power distribution coefficient calculated by the transmission power determination unit 8. Next, the transmission beam forming unit 9 selects a predetermined beam, that is, a selected beam, based on transmission weight information from the beam selection unit 411 for each transmission data frame sequence signal multiplied by the power distribution coefficient. Baseband symbol data multiplied by transmission weights forming a beam is generated. After that, digital data that is baseband symbol data is digital / analog converted by a digital / analog converter (not shown), a band limiting filter, and a frequency converter, and further band-limited. The converted high frequency signal is output.

  The radio base station antennas 11-1 to 11-s emit the supplied high-frequency signals to a propagation path (space) (not shown) toward the terminal devices 2-1 to 2-s to be spatially multiplexed.

  Here, the operation of the reception processing in the terminal apparatuses 2-1 to 2-s for the signals multiplexed and transmitted in the radio base station apparatus 1-B is the same as that in the first embodiment, and thus the description thereof is omitted.

Regarding the above detailed operation, [1] the transmission weight generation algorithm incorporated in the transmission weight generation units 6-1 to 6-n and [3] the method of determining the transmission power distribution coefficient are the same as those in the first embodiment. Detailed description is omitted. In the following, a detailed description will be given of a transmission weight information selection method in [2] beam selection section 411 that is an operation different from that of the first embodiment.

[2] Detailed Description of Transmission Weight Information Selection Method in Beam Selection Unit 411 Here, a detailed description of the transmission weight information selection method in the beam selection unit 411 will be given.

  The beam selection unit 411 selects transmission weight information that maximizes a predetermined criterion from among a plurality of transmission weight information groups generated by the first to nth transmission weight generation units 6-1 to 6-n. select. As a determination criterion, a predicted value of a physical quantity indicating signal quality such as a signal-to-noise power ratio (SNR) or a signal-to-interference wave power ratio (SINR) received by the terminal apparatus 2-D is used as the other-cell interference information acquisition unit 410. Calculated based on the output from. This point is different from the beam selector 7 in the first embodiment.

  That is, in the first embodiment, when the channel information H (k) and the number of antennas of the terminal device 2-k are plural, assuming that directivity is formed by the reception weight R (k), (Equation 16) is However, in this embodiment, the other cell interference information F (k), which is the output from the other cell interference information acquisition unit 410, is also included (several numbers). 27) is used for SINR evaluation.

  Here, the reception weight R (k) indicates a row vector having Nr (k) elements for the number of reception unit antennas of the terminal device 2-k. In (Expression 27), the subscript “n” indicates the number when the user terminal, that is, each terminal device 2 that performs spatial multiplexing connection, is numbered in order, and in this embodiment, the terminal device 2- 1 to 2-s. As the spatial multiplexing / demultiplexing method information, when there is an interference wave component, the MMSE method, the ZF method, and the eigenvector beam reception method can be applied. The ratio combining reception weight is included.

  As described above, SINRn (k) of each user is calculated using Wn (k) shown in (Expression 27) as a variable. This is all calculated for the outputs of the first to nth transmission weight generation units. Then, the beam selection unit 411 generates transmission weight Ws (k) that is output information from the s-th transmission weight generation unit 6-s that generates a transmission weight that maximizes the sum of the SINRn (k) of each user. Select. Here, k = 1 to Ns.

  As described above, in the fourth embodiment of the present invention, the predicted SINR evaluation is performed by using the other-cell interference information transmitted from the terminal apparatus 2-D. As a result, the predicted SINR reflecting the other-cell interference situation can be calculated using only the channel information, and as a result, the predicted SINR evaluation value can be made closer to the SINR received by the actual terminal apparatus.

  Therefore, since the transmission weight can be selected using such a predicted SINR, a more optimal transmission weight can be selected, the communication quality of the terminal device 2 performing communication can be improved, and the capacity of the communication system can be increased. An increase can be aimed at.

  In addition, since the predicted SINR is also used when calculating the transmission power allocation coefficient, more optimal power allocation is performed by the effect that the predicted SINR evaluation value can be made closer to the SINR received by the actual terminal device. Can do.

  Since the communication quality of the terminal device 2 that performs communication by such transmission power control can be ensured at a necessary and sufficient level and the transmission power is not increased more than necessary, the present embodiment is applied to the cellular system. In this case, inter-cell interference can be reduced, and the capacity of the communication system can be increased.

  In the present embodiment, the other cell interference information is transmitted from the terminal device 2-D to the radio base station device 1-B. However, as another configuration, the configuration of the terminal device 2-E shown in FIG. 16 is applied. May be. The terminal device 2-E in FIG. 16 is different from the terminal device 2-D in that a spatial multiplexing transmission availability determination unit 303 is provided between the other cell interference detection unit 302 and the transmission unit 212-C in FIG. .

  Here, the spatial multiplexing transmission availability determination unit 303 compares the output value of the other cell interference detection unit 302 with a predetermined threshold value 304, and performs spatial multiplexing transmission when the other cell interference is larger than the predetermined threshold value. In such a case, it is determined that sufficient communication quality cannot be ensured, and the terminal apparatus 2-E transmits spatial multiplexing transmission prohibition information that does not perform spatial multiplexing transmission to the radio base station apparatus 1-B as other cell interference information. . On the other hand, the radio base station apparatus 1-B acquires the other-cell interference information and performs communication in a mode in which spatial multiplexing transmission is not performed when the spatial multiplexing transmission prohibition information is included therein.

  With the configuration as described above, it is possible for the terminal device 2 to determine whether or not spatial multiplexing transmission is possible according to the other cell interference situation. This is because the threshold setting for other cell interference generally depends on the performance of the reception method of the terminal device, and therefore the radio base station device 1 cannot make a unified determination. Based on the determination result, control of the spatial multiplexing transmission of the radio base station apparatus 1 can be realized in a more suitable form. Thereby, communication quality can be ensured particularly in an area where interference from other cells such as a cell edge cannot be ignored.

  With the operation described above, according to the present embodiment, it is possible to improve and secure communication quality and improve the system capacity by spatial multiplexing transmission associated therewith under various inter-cell interference situations.

  In addition, according to the other situation of this invention, the following invention is included.

According to the first invention, based on channel information for a plurality of terminal apparatuses to be subjected to spatial multiplexing transmission, a plurality of transmission weight information used for forming transmission beams to be transmitted to the plurality of terminal apparatuses are generated by different algorithms. A transmission weight generation unit, a beam selection unit that selects any one of the plurality of transmission weight information generated by the algorithm, and the selected transmission weight information. And a transmission beam forming unit to be formed.
According to a second aspect of the present invention, the radio base station apparatus further includes a transmission power determining unit that determines transmission power of the spatial multiplexing transmission based on the selected transmission weight information.
According to a third aspect of the invention, the beam selection unit is a radio base station apparatus that selects transmission weight information based on information indicating a signal-to-interference noise power ratio in the terminal apparatus.
Further, according to the fourth invention, the beam selection unit transmits a transmission weight based on information indicating a signal-to-interference noise power ratio in the terminal device including other-cell interference information notified from the terminal device. A radio base station apparatus that selects information.
According to a fifth aspect of the present invention, the beam selection unit uses the predicted reception weight that predicts the reception weight at the terminal device when the terminal device can be received by a plurality of antennas, and then transmits the transmission weight. A radio base station apparatus that selects information.
According to a sixth aspect of the invention, the predicted reception weight is a radio base station apparatus that is a weight that forms a maximum ratio combined reception beam.
According to a seventh aspect of the invention, the predicted reception weight is a radio base station apparatus that is a left singular vector obtained by singular value decomposition of a channel matrix.
According to an eighth aspect of the invention, the predicted reception weight is a radio base station apparatus that is a weight that forms a least square error beam.
According to a ninth aspect of the present invention, the predicted reception weight is a radio base station apparatus that is a weight for forming a zero forcing beam.
According to a tenth aspect of the present invention, the predicted reception weight is a radio base station apparatus that is a weight formed based on a spatial demultiplexing algorithm notified from a terminal apparatus.
According to the eleventh aspect of the present invention, the predicted reception weight is a weight for prohibiting spatial multiplexing transmission when the determination result indicating whether spatial multiplexing transmission is possible or not notified from the terminal apparatus is prohibition determination. A certain radio base station apparatus.
According to a twelfth aspect of the invention, the beam selection unit is a radio base station apparatus that selects a transmission weight generation unit having a specific algorithm in advance based on the channel information.
According to the thirteenth invention, one of the plurality of transmission weight generation units is a radio base station apparatus that generates transmission weight information for forming an eigenvector beam for the terminal apparatus.
According to the fourteenth aspect, one transmission weight generation unit among the plurality of transmission weight generation units generates transmission weight information that does not reduce or give interference to a terminal device other than a desired terminal device. A wireless base station device.
According to the fifteenth aspect of the invention, one transmission weight generation unit among the plurality of transmission weight generation units assumes that the desired terminal device receives the maximum ratio combining reception, and is a terminal device other than the desired terminal device. Is a radio base station apparatus that generates transmission weight information that does not reduce or give interference.
Further, according to the sixteenth aspect, one of the plurality of transmission weight generation units, the transmission base generation unit that generates transmission weight information forming a transmission weight vector in which all components are zero .
According to the seventeenth aspect, one transmission weight generation unit among the plurality of transmission weight generation units is a radio base station apparatus that generates transmission weight information that forms a fixed transmission weight vector in advance.
According to an eighteenth aspect of the invention, the transmission beam forming unit inserts a known signal sequence in advance for each signal that is spatially multiplexed using a transmission weight vector formed from the selected transmission weight information. Wireless base station apparatus that performs spatial multiplexing transmission.
According to the nineteenth invention of the second aspect, a channel estimation unit that performs channel estimation based on a previously known signal sequence assigned to each spatially multiplexed signal, and a desired signal from a spatially multiplexed signal And a spatial multiplexing / demultiplexing unit that generates reception weights for separating and outputting signals.
According to a twentieth aspect of the invention, the reception weight is a terminal device that generates a maximum ratio combined weight based on a value obtained as a result of the channel estimation.
According to a twenty-first aspect of the present invention, the reception weight is a terminal device that generates a least square error weight based on a result of the channel estimation.
According to a twenty-second aspect, in the terminal device, the reception weight is a left singular vector corresponding to a maximum singular value obtained by singular value decomposition of the channel matrix obtained as a result of the channel estimation. is there.
According to the twenty-third aspect, the spatial demultiplexing method storage unit stores spatial demultiplexing method information related to a spatial demultiplexing algorithm when a desired signal is separated from the spatial demultiplexed signal; A terminal unit further including a transmission unit that notifies the radio base station device.
According to the twenty-fourth invention, the radio base station apparatus uses the other cell interference detection unit that detects an interference situation from another cell, and the detected value detected by the other cell interference detection unit as the other cell interference information. A terminal unit further including a transmitting unit for notifying to.
According to the twenty-fifth aspect of the present invention, whether or not spatial multiplex transmission is possible is determined based on another cell interference detection unit that detects an interference situation from another cell and a detection value detected by the other cell interference detection unit. A terminal apparatus further comprising: a spatial multiplexing transmission availability determination unit; and a transmission unit that notifies the base station apparatus of the spatial multiplexing transmission availability determination result.
According to the twenty-sixth aspect of the third aspect, when the detection value detected by the other-cell interference detection unit exceeds a predetermined value, the spatial multiplexing transmission availability determination unit determines that spatial multiplexing transmission is prohibited. And a terminal device that notifies the base station device of the prohibition determination result.
According to the twenty-seventh aspect, channel information between the terminal device and the radio base station is extracted from a received signal from the terminal device, and a plurality of spatial multiplexing transmissions are to be performed based on the extracted channel information. A step for obtaining a spatial correlation coefficient between terminal devices, a first method for generating a transmission weight using an algorithm for minimizing interference with other terminal devices, and an algorithm for reducing interference with other terminal devices Based on a predetermined selection processing method from the second method for generating a transmission weight without using a third method for generating a transmission weight using an algorithm for generating a single transmission weight, And a step of selecting a method with the best communication quality according to the spatial correlation coefficient obtained in the step.
According to the twenty-eighth aspect of the invention, the selection processing method selects the second method in a region where the spatial correlation coefficient ρ is 0 ≦ ρ ≦ 0.3, and the spatial correlation coefficient ρ is In the region where 0.4 ≦ ρ ≦ 0.6, the first method is selected, and in the region where the spatial correlation coefficient ρ is 0.8 ≦ ρ ≦ 1, the third method is selected. Communication method.

  The radio base station apparatus and terminal apparatus according to the present invention have a function of selecting optimum weight information according to spatial correlation characteristics between terminal apparatuses to be spatially multiplexed from a plurality of transmission weight information groups based on different algorithms. As a result, the system capacity can be improved after simplifying the radio base station apparatus and reducing the processing delay, which is useful in the radio communication field using spatial multiplexing.

DESCRIPTION OF SYMBOLS 1,100 Radio base station apparatus 2-1, 2-2, 2-s, 2-A, 2-B Terminal apparatus 3-1, 3-2, 3-s Transmission signal generation part 4 Channel information acquisition part 5 Transmission Weight determining unit 6-1, 6-2, 6-n Transmission weight generating unit 7 Beam selecting unit 8 Transmission power determining unit 9 Transmit beam forming unit 11-1, 11-2, 11-s, 60 Radio base station antenna 20 -1, 20-m, 62 reception unit antenna 107-a, 107-b selection switch unit 216 transmission unit antenna 221-1, 221-m reception unit 222 channel estimation unit 223 spatial demultiplexing unit 224 demodulation unit

Claims (20)

Based on channel information for a plurality of terminal devices to be spatially multiplexed, a plurality of transmission weight generation units that generate transmission weight information used for forming transmission beams to be transmitted to the plurality of terminal devices by different algorithms;
A beam selection unit for selecting any transmission weight information among a plurality of transmission weight information generated by the algorithm;
A transmission beam forming unit that forms the transmission beam using the selected transmission weight information;
A wireless base station apparatus. Based on the selected transmission weight information, a transmission power determination unit that determines transmission power of the spatial multiplexing transmission,
The radio base station apparatus according to claim 1, further comprising: The beam selector
The radio base station apparatus according to claim 1, wherein transmission weight information is selected based on information indicating a signal-to-interference noise power ratio in the terminal apparatus. The beam selector
The radio base station apparatus according to claim 1, wherein transmission weight information is selected based on information indicating a signal-to-interference noise power ratio in the terminal apparatus including other-cell interference information notified from the terminal apparatus. The beam selector
2. The radio base station apparatus according to claim 1, wherein when the terminal apparatus can be received by a plurality of antennas, transmission weight information is selected using a predicted reception weight obtained by predicting a reception weight at the terminal apparatus. The predicted reception weight is
6. The radio base station apparatus according to claim 5, wherein the weight is a weight for forming a maximum ratio combined reception beam. The predicted reception weight is
6. The radio base station apparatus according to claim 5, wherein the radio base station apparatus is a left singular vector obtained by singular value decomposition of a channel matrix. The predicted reception weight is
6. The radio base station apparatus according to claim 5, wherein the weight is a weight for forming a least square error beam. The predicted reception weight is
6. The radio base station apparatus according to claim 5, wherein the weight is a weight for forming a zero forcing beam. The predicted reception weight is
The radio base station apparatus according to claim 5, wherein the weight is formed based on a spatial demultiplexing algorithm notified from the terminal apparatus. The predicted reception weight is
The radio base station apparatus according to claim 5, wherein when the determination result indicating whether or not spatial multiplexing transmission is possible is a prohibition determination, the radio base station apparatus is a weight that prohibits spatial multiplexing transmission. The beam selector
The radio base station apparatus according to claim 1, wherein a transmission weight generation unit having a specific algorithm is selected in advance based on the channel information. One transmission weight generation unit among the plurality of transmission weight generation units is
The radio base station apparatus according to claim 1 or 12, wherein transmission weight information for forming an eigenvector beam for the terminal apparatus is generated. One transmission weight generation unit among the plurality of transmission weight generation units is
The radio base station apparatus according to claim 1 or 12, wherein transmission weight information that does not reduce or give interference to a terminal apparatus other than a desired terminal apparatus is generated. One transmission weight generation unit among the plurality of transmission weight generation units is
13. The radio base according to claim 1 or 12, wherein transmission weight information is generated so as not to reduce or give interference to a terminal device other than the desired terminal device on the assumption that the desired terminal device receives maximum ratio combining reception. Station equipment. One transmission weight generation unit among the plurality of transmission weight generation units is
The radio base station apparatus according to claim 1 or 12, wherein transmission weight information that forms a transmission weight vector in which all components are zero is generated. One transmission weight generation unit among the plurality of transmission weight generation units is
The radio base station apparatus according to claim 1 or 12, wherein transmission weight information that forms a fixed transmission weight vector in advance is generated. The transmission beam former is
The radio base station according to claim 1 or 12, wherein a known signal sequence is inserted in advance and spatially multiplexed for each signal spatially multiplexed using a transmission weight vector formed from the selected transmission weight information. apparatus. Channel information between the terminal device and the radio base station is extracted from a received signal from the terminal device, and a spatial correlation coefficient between a plurality of terminal devices to be spatially multiplexed is obtained based on the extracted channel information. Steps,
A first method for generating transmission weights using an algorithm that minimizes interference with other terminal devices, and a second method for generating transmission weights without using algorithms that reduce interference with other terminal devices From the third method of generating a transmission weight using an algorithm for generating a single transmission weight, communication is performed according to the spatial correlation coefficient obtained in the above step based on a predetermined selection processing method. Selecting the method with the best quality;
A wireless communication method.   The selection processing method selects the second method in a region where the spatial correlation coefficient ρ is 0 ≦ ρ ≦ 0.3, and the spatial correlation coefficient ρ is 0.4 ≦ ρ ≦ 0.6. The radio communication method according to claim 19, wherein the first method is selected in a region, and the third method is selected in a region where the spatial correlation coefficient ρ is 0.8 ≦ ρ ≦ 1.

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