JP5441811B2 - Receiving device, base station device, wireless communication system, propagation path estimation method, control program, and integrated circuit - Google Patents

Description

  The present invention relates to a radio communication system that demodulates reference signals transmitted at different frequency arrangements, and more particularly to a propagation path estimation method in a receiving apparatus.

  The standardization of the LTE (Long Term Evolution) system, which is the wireless communication system for the 3.9th generation mobile phone, is almost completed, and recently, the LTE-A (4th generation wireless communication system, which is a further development of the LTE system). LTE-Advanced, IMT-A, etc.) are being standardized. Generally, in the uplink of a mobile communication system (communication from a mobile station to a base station), the mobile station becomes a transmitting station, so that the power utilization efficiency of the amplifier can be maintained high with limited transmission power, and the peak power A low single carrier method (LTE adopts a single carrier frequency division multiple access (SC-FDMA) method) is effective. SC-FDMA is also called DFT-S-OFDM (Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing) or DFT-precoded OFDM.

  In LTE-A, in order to further improve the frequency utilization efficiency, for a terminal having a sufficient transmission power, the SC-FDMA spectrum is divided into clusters composed of a plurality of subcarriers, and each cluster is arbitrarily assigned on the frequency axis. To newly support an access method called Clustered DFT-S-OFDM (also referred to as Dynamic Spectrum Control (DSC), Single Carrier Adaptive Spectrum Allocation (SC-ASA), etc.) arranged at a frequency of Has been determined. Further, introduction of a multi-user MIMO (Multiple-Input Multiple-Output) scheme is being studied as a technique for improving uplink throughput in LTE-A.

  FIG. 10 is a diagram illustrating the concept of uplink multi-user MIMO. Here, description will be made assuming that the number of mobile station apparatuses to be connected is two. As shown in FIG. 10, in the multi-user MIMO system, the first mobile station apparatus 1-1 and the second mobile station apparatus 1-2 (hereinafter referred to as the first mobile station apparatus 1-1 and the second mobile station). The station apparatus 1-2 is collectively referred to as the mobile station apparatus 1) and transmits to the base station apparatus 3 using the same time and the same frequency, and performs MIMO separation using two or more receiving antennas of the base station apparatus 3. As a result, the number of mobile station apparatuses that can be connected simultaneously can be expanded in the spatial direction, thereby improving the throughput.

  Furthermore, when Clustered DFT-S-OFDM is used, throughput is improved by multiplexing the frequency bandwidth and frequency of users to be spatially multiplexed so as not to impair scheduling flexibility by distributed arrangement. (For example, Non-Patent Document 1). In LTE, when a plurality of mobile station apparatuses 1 transmit using the same frequency, if the frequency bandwidths of these mobile station apparatuses 1 are the same and use the same frequency, a channel estimation signal (DMRS: DeModulation Reference Since the orthogonal signal is multiplied by the frequency signal with respect to (Signal), the propagation path characteristics from each mobile station apparatus 1 can be estimated, and therefore, separation is possible.

  However, since the method of Non-Patent Document 1 uses different bandwidths, LTE orthogonal codes cannot be used. Therefore, orthogonal codes on the time axis called OCC (Orthogonal Cover Code) and IFDMA (Interleaved Frequency) are used. An orthogonal code on the frequency axis called “Division Multiple Access” has been proposed. 11A and 11B show the concept of OCC and IFDMA.

  FIG. 11A is a diagram illustrating a configuration of a subframe that is a minimum radio resource on the time axis. Reference signals (DMRS: DeModulation Reference Signal) 101 and 102 for channel estimation are arranged in the subframe, and the rest are data symbols. In OCC, subcarriers assigned to frequency signals are the same as those of LTE, and DMRSs 101 and 102 having two symbols on the time axis are multiplied by orthogonal codes to maintain orthogonality. In this method, since DMRS has only two symbols, only two multiplexing can be performed in the spatial domain, but important backward compatibility can be maintained in LTE-A.

  FIG. 11B is a diagram illustrating IFDMA. DMRS subcarriers 105 to 111 are allocated on the frequency axis. In the DMDMA, as in the DMRS subcarriers 105 to 111 in FIG. 11B, the DMRSs are orthogonalized on the frequency axis by arranging the frequencies in a comb-like shape at regular intervals. In this case, although the number of mobile station apparatuses that can be multiplexed increases according to the number of subcarriers included between the comb teeth, there is a problem that orthogonality is lost because the LTE subcarrier allocation method is not used. Therefore, application of OCC is discussed in LTE-A.

Nokia, NSN, R1-094651

  Furthermore, when IFDMA is applied, there is a problem that orthogonality with LTE cannot be maintained, which is not suitable from the viewpoint of backward compatibility. However, considering the application of only OCC, the number of mobile station apparatuses that can be multiplexed in the spatial domain is limited. Therefore, when further improvement in throughput is considered, maintaining orthogonality such as IFDMA is also important. When the number of LTE-A mobile station devices 1 increases from that of LTE mobile devices 1, it is not desirable to limit the number of spatial multiplexing even though LTE is not connected.

  The present invention has been made in view of such circumstances, and even when IFDMA is applied, a receiving device, a base station device, a wireless communication system, a propagation path estimation method, which can maintain orthogonality with LTE, An object is to provide a control program and an integrated circuit.

  (1) In order to achieve the above object, the present invention takes the following measures. That is, the receiving apparatus of the present invention is a receiving apparatus that receives a radio signal in which a plurality of reference signals having different allocation intervals of assigned subcarriers are multiplexed, and any one reference signal from the received radio signal. Excluding all reference signals except for estimating the propagation path characteristic of any one of the reference signals, based on the received wireless signal and the estimated propagation path characteristic of any one of the reference signals, The propagation path characteristic of any other reference signal is estimated.

  In this way, the receiving apparatus excludes all reference signals other than any one of the reference signals from the received radio signal, estimates the propagation path characteristics of any one of the reference signals, and receives the received radio signal and Since the propagation path characteristics of any other reference signal are estimated based on the estimated propagation path characteristics of any one of the reference signals, even if the mobile station apparatus uses DMRS based on IFDMA, the LTE reference signal arrangement and Even if the IFDMA reference signal arrangement is mixed, the receiving apparatus can demodulate both data signals. As a result, flexible multi-user MIMO can be efficiently realized without being aware of orthogonality due to orthogonal codes.

  (2) Moreover, in the receiving apparatus of the present invention, the radio signal includes a reference signal assigned to consecutively arranged subcarriers and a reference signal assigned to discretely arranged subcarriers. It is characterized by that.

  As described above, since the radio signal includes the reference signal assigned to the continuously arranged subcarriers and the reference signal assigned to the discretely arranged subcarriers, the receiving apparatus can perform DMRS based on IFDMA. Even when LTE is used, even when LTE reference signal arrangement and IFDMA reference signal arrangement are mixed, both data signals can be demodulated. As a result, flexible multi-user MIMO can be efficiently realized without being aware of orthogonality due to orthogonal codes.

  (3) In the reception apparatus of the present invention, the radio signal includes a reference signal assigned to at least one subcarrier group including a plurality of subcarriers arranged in succession, and sub-bands arranged discretely. And a reference signal assigned to the carrier.

  In this way, a radio signal includes a reference signal assigned to at least one subcarrier group composed of a plurality of subcarriers arranged continuously, and a reference signal assigned to subcarriers arranged discretely. Therefore, the receiving apparatus receives both data signals when a reference signal in which frequency signals such as Clustered DFT-S-OFDM are distributed in a plurality of clusters and a comb-like reference signal are multiplexed. Demodulation is possible. As a result, flexible multi-user MIMO can be efficiently realized without being aware of orthogonality due to orthogonal codes.

  (4) Further, in the receiving apparatus of the present invention, the propagation path characteristics of the reference signal are estimated in ascending order of allocated subcarrier arrangement intervals.

  Thus, since the receiving apparatus estimates the propagation characteristics of the reference signal in ascending order of the allocated subcarrier arrangement interval, even when the mobile station apparatus uses DMRS based on IFDMA, the reference signal arrangement of LTE Even if the IFDMA reference signal arrangement is mixed, the base station apparatus can demodulate both data signals. As a result, flexible multi-user MIMO can be efficiently realized without being aware of orthogonality due to orthogonal codes.

  (5) Moreover, the base station apparatus of this invention is provided with the receiver in any one of (1) to (5), It is characterized by the above-mentioned.

  As described above, since the base station apparatus includes the receiving apparatus according to any one of (1) to (5), even when the mobile station apparatus uses DMRS based on IFDMA, LTE reference signal arrangement and IFDMA reference are performed. Even when the signal arrangement is mixed, the base station apparatus can demodulate both data signals. As a result, flexible multi-user MIMO can be efficiently realized without being aware of orthogonality due to orthogonal codes.

  (6) Moreover, the radio | wireless communications system of this invention is comprised from a mobile station apparatus and the base station apparatus as described in (5), It is characterized by the above-mentioned.

  As described above, since the wireless communication system includes the mobile station apparatus and the base station apparatus described in (5), even when the mobile station apparatus uses DMRS based on IFDMA, LTE reference signal arrangement and IFDMA are used. Even when the reference signal arrangements are mixed, the base station apparatus can demodulate both data signals. As a result, flexible multi-user MIMO can be efficiently realized without being aware of orthogonality due to orthogonal codes.

  (7) Further, the propagation path estimation method of the present invention is a propagation path estimation method of a receiving apparatus that receives a radio signal in which a plurality of reference signals having different allocation intervals of assigned subcarriers are multiplexed. In the apparatus, a step of receiving a radio signal, a step of excluding all reference signals other than any one of the reference signals from the received radio signal, and a step of estimating a propagation path characteristic of the one of the reference signals And estimating the propagation path characteristic of any other reference signal based on the received wireless signal and the estimated propagation path characteristic of any one of the reference signals.

  In this way, the receiving apparatus excludes all reference signals other than any one reference signal from the received radio signal, estimates the propagation path characteristics of any one reference signal, and estimates the received radio signal and Since the propagation path characteristic of any other reference signal is estimated based on the propagation path characteristic of any one reference signal, even when the mobile station apparatus uses DMRS by IFDMA, the reference signal arrangement of LTE and IFDMA Even when the reference signal arrangement is mixed, the base station apparatus can demodulate both data signals. As a result, flexible multi-user MIMO can be efficiently realized without being aware of orthogonality due to orthogonal codes.

  (8) The control program of the present invention is a control program for a receiving apparatus that receives a radio signal in which a plurality of reference signals having different allocated subcarrier arrangement intervals are multiplexed, and receives the radio signal. A process, a process of excluding all reference signals other than any one reference signal from the received radio signal, a process of estimating a propagation path characteristic of the any one reference signal, the received radio signal, and Based on the estimated propagation path characteristic of any one of the reference signals, a process including the process of estimating the propagation path characteristics of any other reference signal is commanded to be readable and executable by a computer. It is characterized by that.

  In this way, the receiving apparatus excludes all reference signals other than any one reference signal from the received radio signal, estimates the propagation path characteristics of any one reference signal, and estimates the received radio signal and Since the propagation path characteristic of any other reference signal is estimated based on the propagation path characteristic of any one reference signal, even when the mobile station apparatus uses DMRS by IFDMA, the reference signal arrangement of LTE and IFDMA Even when the reference signal arrangement is mixed, the base station apparatus can demodulate both data signals. As a result, flexible multi-user MIMO can be efficiently realized without being aware of orthogonality due to orthogonal codes.

  (9) Further, the integrated circuit of the present invention is an integrated circuit that causes the wireless communication device to perform a plurality of functions by being mounted on the wireless communication device, and has a plurality of allocated subcarrier arrangement intervals different from each other. A function of receiving a radio signal multiplexed with a reference signal, a function of excluding all reference signals other than any one of the received radio signals from the received radio signal, and propagation path characteristics of the one of the reference signals A series of functions including: a function of estimating a propagation path characteristic of any other reference signal based on a propagation path characteristic of the received radio signal and any one of the estimated reference signals In the wireless communication device.

  In this way, the receiving apparatus excludes all reference signals other than any one reference signal from the received radio signal, estimates the propagation path characteristics of any one reference signal, and estimates the received radio signal and Since the propagation path characteristic of any other reference signal is estimated based on the propagation path characteristic of any one reference signal, even when the mobile station apparatus uses DMRS by IFDMA, the reference signal arrangement of LTE and IFDMA Even when the reference signal arrangement is mixed, the base station apparatus can demodulate both data signals. As a result, flexible multi-user MIMO can be efficiently realized without being aware of orthogonality due to orthogonal codes.

  According to the present invention, it is possible to demodulate both data signals even when DMRS using IFDMA is used or when LTE reference signal arrangement and IFDMA reference signal arrangement are mixed. As a result, flexible multi-user MIMO can be efficiently realized without being aware of orthogonality due to orthogonal codes.

It is a block diagram which shows an example of the base station apparatus 3 which is a receiver concerning the 1st Embodiment of this invention. It is a figure which shows the subcarrier arrangement | positioning 301 of DMRS of the 1st mobile station apparatus 1-1 which concerns on the 1st Embodiment of this invention, and the subcarrier arrangement | positioning 303 of DMRS of the 2nd mobile station apparatus 1-2. FIG. 3 is a diagram illustrating an example of a frequency signal that has received the reference signal of FIG. 2 in the first embodiment of the present invention. In the 1st Embodiment of this invention, after estimating some propagation path characteristics, it is a figure which shows the concept of performing the propagation path estimation in all the subcarriers by extrapolation, interpolation, etc. FIG. In the first embodiment of the present invention, the propagation path characteristics of the mobile station apparatus 1 of the LTE system are estimated and complemented, and then the second mobile station is subtracted from the replica of the continuously arranged reference signal from the received signal. It is a figure which shows the concept which estimates the propagation path characteristic of the apparatus 1-2. It is a block diagram which shows an example of the base station apparatus 3 which is a receiver concerning the 2nd Embodiment of this invention. It is a figure which shows the subcarrier arrangement | positioning 801 of the 1st mobile station apparatus 1-1 based on the 2nd Embodiment of this invention, and the subcarrier arrangement | positioning 303 of the 2nd mobile station apparatus 1-2. In the second embodiment of the present invention, after estimating and complementing the propagation path characteristics of the mobile station apparatus 1 of the LTE system, the second mobile station is subtracted from the replica of the reference signal in the distributed arrangement from the received signal. It is a figure which shows the concept which estimates the propagation path characteristic of the apparatus 1-2. In the 3rd Embodiment of this invention, it is a figure which shows an example of a reference signal arrangement | positioning when the number of the mobile station apparatuses 1 is four. It is a figure which shows the concept of the uplink multiuser MIMO. It is a figure which shows the structure of the sub-frame which is the minimum radio | wireless resource of a time axis. It is a figure showing IFDMA.

  Embodiments of the present invention will be described below with reference to the drawings. In the following embodiment, the number of mobile station apparatuses accessing the base station apparatus 3 by multiuser MIMO is 2, and the minimum unit of frequency resources (the number of subcarriers included in a resource block) is 12, which is included in the system band. Although the description will be made assuming that the number of resource blocks NRB is 4, it is not limited to this. Here, uplink multi-user MIMO including the background art is shown as an example. However, since the essence of the present invention is a receiving apparatus that can demodulate reference signals transmitted at different frequency arrangements, It is not limited to user MIMO.

[First Embodiment]
FIG. 1 is a block diagram illustrating an example of a base station apparatus 3 which is a receiving apparatus according to the first embodiment of the present invention. The received signal is received by the receiving antenna 201 and is down-converted from a radio frequency to a baseband signal by the radio unit 203. Next, the CP (Cyclic Prefix) removing unit 205 removes the CP, which is a later copy of the transmission signal added at the time of transmission, and the FFT (Fast Fourier Transform) unit 207 converts it into a frequency signal. The reference signal separation unit 209 separates the reference signal for channel estimation from the frequency signal, and the subcarrier removal unit 211 removes the subcarrier of the frequency to which the reference signal of the second mobile station apparatus 1-2 is assigned. The first propagation path estimation unit 213 estimates the propagation path characteristics of the first mobile station apparatus 1-1 transmitted by the same transmission method as LTE from the subcarrier received signal that has not been removed.

  Thereafter, the propagation path characteristic subtraction unit 215 subtracts the replica of the continuously arranged reference signal output from the reference signal separation unit 209 from the original reception signal, and the second propagation path estimation unit 217 performs the second mobile station. The propagation path characteristic from the device 1-2 to the base station device 3 is estimated. Thereafter, the channel estimation value output from the first channel estimation unit 213 and the channel estimation value output from the second channel estimation unit 217 are input to the signal detection unit 219, and the reference signal separation unit 209 is input. The signal of each mobile station apparatus 1 is detected by the MIMO separation process from the data signal output by. Thereafter, the estimated signal of each mobile station apparatus 1 is input to the demodulator 221 to convert the symbol into a bit-level received signal, and the decoder 223 performs error correction decoding to obtain a decoded bit sequence. FIG. 2 shows DMRS subcarrier allocation of each mobile station apparatus 1.

  FIG. 2 is a diagram showing a DMRS subcarrier arrangement 301 of the first mobile station apparatus 1-1 and a DMRS subcarrier arrangement 303 of the second mobile station apparatus 1-2 according to the first embodiment of the present invention. It is. The 1st mobile station apparatus 1-1 shall be the mobile station apparatus 1 based on a LTE system. Reference signals with such an arrangement are referred to as continuous arrangement reference signals. Further, FIG. 2 shows a DMRS subcarrier arrangement 303 based on IFDMA. The reference signal having such an arrangement is referred to as a comb-shaped reference signal.

  FIG. 3 is a diagram illustrating an example of a frequency signal received from the reference signal of FIG. 2 in the first embodiment of the present invention. In FIG. 3, a received signal 401 is a received signal affected by propagation path fluctuations observed in the base station apparatus 3, and a received signal 403 is a received signal from the first mobile station apparatus 1-1, a received signal 405. Is a received signal from the second mobile station apparatus 1-2. As shown in FIG. 3, the received signal observed by the base station apparatus 3 is represented by the sum of the received signal 403 and the received signal 405 like the received signal 401. When this is specifically written as an expression, it is expressed as Expression (1).

Ｒ（ｋ）は、ｋ番目のサブキャリアの受信信号を示しており、ｍはＩＦＤＭＡにおけるサブキャリアを配置する間隔、ｋ’は０以上の整数、ｐはＩＦＤＭＡにおける最初のサブキャリアが配置されるサブキャリア番号であり、１からｍ−１の値のいずれかである。例えば、ｐ＝２、ｍ＝４の場合には、ＩＦＤＭＡのサブキャリアが配置されるインデックスは、２、６、１０、１４、・・・となる。また、Ｈ_１（ｋ）、Ｈ_２（ｋ）は、それぞれ第１の移動局装置１−１から基地局装置３への伝搬路特性、第２の移動局装置１−２から基地局装置３への伝搬路特性を表し、Ｓ_１（ｋ）、Ｓ_２（ｋ）はそれぞれ第１の移動局装置１−１および第２の移動局装置１−２のＤＭＲＳの振幅を表す。ただし、式（１）では、簡単のため干渉および雑音成分は省略している。

R (k) represents a received signal of the kth subcarrier, m is an interval for arranging subcarriers in IFDMA, k ′ is an integer of 0 or more, and p is a first subcarrier in IFDMA. A subcarrier number, which is any value from 1 to m-1. For example, when p = 2 and m = 4, the indexes where IFDMA subcarriers are arranged are 2, 6, 10, 14,. H ₁ (k) and H ₂ (k) are the propagation path characteristics from the first mobile station apparatus 1-1 to the base station apparatus 3, respectively, and the second mobile station apparatus 1-2 to the base station apparatus 3 respectively. And S ₁ (k) and S ₂ (k) represent the DMRS amplitudes of the first mobile station apparatus 1-1 and the second mobile station apparatus 1-2, respectively. However, in Equation (1), interference and noise components are omitted for simplicity.

  For the received signal obtained in this way, the propagation path characteristic of the first mobile station apparatus 1-1 is estimated from the frequency that is not arranged by IFDMA in Expression (1). In equation (1), propagation path characteristics other than k = mk ′ + p are expressed by the following equation (2).

ただし、Ｈ_１’（ｋ）はｋ番目のサブキャリアの第１の移動局装置１−１の伝搬路推定値である。このように第１の移動局装置１−１の伝搬路特性を推定し、第２の移動局装置１−２が割り当てたサブキャリア以外の伝搬路特性を推定した後、ｋ＝ｍｋ’＋ｐにおける伝搬路特性を、外挿や内挿などにより全てのサブキャリアにおける伝搬路推定を行なう。この概念を図４に示す。

However, H ₁ ′ (k) is a propagation path estimation value of the first mobile station apparatus 1-1 of the kth subcarrier. Thus, after estimating the propagation path characteristics of the first mobile station apparatus 1-1 and estimating the propagation path characteristics other than the subcarriers assigned by the second mobile station apparatus 1-2, k = mk ′ + p The propagation path characteristics are estimated for all subcarriers by extrapolation or interpolation. This concept is illustrated in FIG.

  FIG. 4 is a diagram illustrating a concept of performing channel estimation on all subcarriers by extrapolation, interpolation, or the like after estimating some channel characteristics in the first embodiment of the present invention. The propagation path characteristic 501 is the propagation path characteristic of the first mobile station apparatus 1-1 estimated by the expression (2), and the propagation path characteristic 503 is calculated from the propagation path characteristic estimated by the expression (2). It is a propagation path characteristic estimated by processing such as insertion or extrapolation and estimated for all subcarriers. As a method of interpolation or extrapolation, interpolation may be performed using a generally used linear function or quadratic function, or a DFT (Discrete Fourier Transform) method or MMSE (Minimum Mean Square Error). Complementation such as law may be used, and the complementation method is not limited. Next, subtraction from the received signal obtained by Expression (1) is performed using the subcarrier propagation path estimated value satisfying k = mk ′ + p. At this time, the propagation path estimated value is expressed by Equation (3).

ただし、右辺第２項は、連続配置の参照信号のレプリカである。このように、ＬＴＥシステムの移動局装置１の伝搬路特性をＩＦＤＭＡによりＤＭＲＳを送信する移動局装置１が使用していない周波数から推定し、補完した後、受信信号から連続配置の参照信号のレプリカを減算することで、第２の移動局装置１−２の伝搬路特性も推定する。この概念を図５に示す。

However, the second term on the right side is a replica of reference signals arranged continuously. As described above, the propagation path characteristics of the mobile station apparatus 1 in the LTE system are estimated from frequencies not used by the mobile station apparatus 1 that transmits DMRS by IFDMA, and after complementation, a replica of reference signals continuously arranged from the received signal. To estimate the propagation path characteristics of the second mobile station apparatus 1-2. This concept is illustrated in FIG.

  FIG. 5 shows the first embodiment of the present invention, after estimating and complementing the propagation path characteristics of the mobile station apparatus 1 of the LTE system, subtracting a replica of the continuously arranged reference signal from the received signal. It is a figure which shows the concept which estimates the propagation path characteristic of 2 mobile station apparatuses 1-2. As shown in FIG. 5, the propagation path characteristic 601 from the second mobile station apparatus 1-2 to the base station apparatus 3 is subtracted from the reception signal 401 by the propagation path characteristic 503 estimated as described above. Can be estimated. Thereafter, the propagation path characteristic 601 from the second mobile station apparatus 1-2 to the base station apparatus 3 is estimated by using complementary processing such as DFT method and MMSE method for the estimated propagation path characteristic 601. Can do. As a result, flexible multi-user MIMO can be efficiently realized without being aware of orthogonality due to orthogonal codes.

[Second Embodiment]
The second embodiment shows a propagation path estimation method when a reference signal in which frequency signals such as Clustered DFT-S-OFDM are distributed in a plurality of clusters and a comb-like reference signal are multiplexed. .

  FIG. 6 is a block diagram showing an example of the base station apparatus 3 which is a receiving apparatus according to the second embodiment of the present invention. The basic configuration is the same as that in FIG. 1, and the blocks denoted by the same reference numerals have the same functions, and thus description thereof is omitted. A newly added block is a subcarrier extraction unit 701. Subcarrier extraction section 701 uses first mobile station apparatus 1-1 before subcarrier removal section 211 removes subcarriers of frequencies to which the reference signal of second mobile station apparatus 1-2 is assigned. Only the selected frequency is left and the received signal of the remaining frequency is set to zero.

  FIG. 7 is a diagram showing a subcarrier arrangement 801 of the first mobile station apparatus 1-1 and a subcarrier arrangement 303 of the second mobile station apparatus 1-2 according to the second embodiment of the present invention. In Clustered DFT-S-OFDM, as shown in the subcarrier arrangement 801 in FIG. 7, transmission signals are distributed and arranged on an arbitrary frequency according to propagation path characteristics, QoS (Quality of Service), and the like on the frequency axis. . Therefore, the reference signal is also distributed and transmitted on the frequency axis. The reference signal in this case is referred to as a distributed reference signal. In the dispersedly arranged reference signals, it is assumed that the reference signals are continuously arranged on the frequency axis in each of the dispersedly arranged clusters.

  FIG. 7 shows an example of reference signals arranged in a distributed manner and transmission signals arranged in a comb shape. It is assumed that the reference signals of the comb-tooth-shaped subcarrier arrangement 303 are simultaneously transmitted as shown in FIG. The basic idea is the same as in the first embodiment.

  FIG. 8 shows a second embodiment of the present invention, in which the propagation path characteristics of the mobile station apparatus 1 of the LTE system are estimated and complemented, and then a replica of the reference signal in a distributed arrangement is subtracted from the received signal. It is a figure which shows the concept which estimates the propagation path characteristic of 2 mobile station apparatuses 1-2. As in the first embodiment, first, the propagation path characteristics 903 of the reference signals distributed in the first mobile station apparatus 1-1 are changed to the subcarriers in which the second mobile station apparatus 1-2 is set. Estimate from the excluded channel characteristics using interpolation. Next, the propagation path characteristic 905 of the second mobile station apparatus 1-2 is estimated by subtracting the propagation path characteristic 903 from the received signal 901.

[Third Embodiment]
As a third embodiment, the case of a reference signal that is further generalized and multiplexed with signals of more than two mobile station apparatuses will be described.

  FIG. 9 is a diagram illustrating an example of reference signal arrangement when the number of mobile station devices 1 is four in the third embodiment of the present invention. In FIG. 9, subcarrier arrangements 1001 and 1007 are arrangements of reference signals transmitted by the transmission method belonging to first mobile station apparatus 1-1 in this specification, and subcarrier arrangements 1003 and 1005 are second movements. This is an arrangement of reference signals transmitted by the transmission method belonging to the station apparatus 1-2. At this time, the bands assigned the same numbers represent the frequencies used by the same mobile station apparatus 1. For example, the band to which the subcarrier arrangement 1003 is attached represents that the mobile station apparatus 1 transmits reference signals distributed and arranged at two places on the frequency axis.

  As described above, even when a plurality of mobile station apparatuses 1 are mixed, by classifying the reference signal of the continuous arrangement, the reference signal of the distributed arrangement, and the comb-shaped reference signal, the propagation path can be applied to the flexible arrangement. Estimation can be performed.

  In the present invention, the case where the comb-tooth-shaped reference signal and the continuous and distributed reference signals are spatially multiplexed has been described. However, when continuous and distributed reference signals are multiplexed, OCC is used. For example, the propagation path characteristics can be estimated with high accuracy in any arrangement. Further, the present invention considers that, for example, as shown in the first embodiment, a reference signal having a subcarrier arrangement interval of 0 and a reference signal having a subcarrier arrangement interval of 3 (natural number) are multiplexed. Therefore, it is naturally applicable even when reference signals having different subcarrier arrangement intervals are multiplexed. For example, when a reference signal with a subcarrier interval of 2 and a reference signal with a subcarrier interval of 4 are multiplexed, first, a reference signal with a subcarrier interval of 4 is arranged from a reference signal with a subcarrier interval of 2 This is possible by estimating the propagation path excluding the frequency and subtracting the reference signal replica having a subcarrier interval of 2 from the received signal. As described above, the present invention also includes a method and apparatus for estimating propagation path characteristics first from a reference signal having a small subcarrier interval and estimating propagation path characteristics obtained from a reference signal having a large subcarrier interval.

  The program that operates in the mobile station apparatus 1 and the base station apparatus 3 related to the present invention is a program (a program that causes a computer to function) that controls the CPU and the like so as to realize the functions of the above-described embodiments related to the present invention. Information handled by these devices is temporarily stored in the RAM at the time of processing, then stored in various ROMs and HDDs, read out by the CPU, and corrected and written as necessary. As a recording medium for storing the program, a semiconductor medium (for example, ROM, nonvolatile memory card, etc.), an optical recording medium (for example, DVD, MO, MD, CD, BD, etc.), a magnetic recording medium (for example, magnetic tape, Any of a flexible disk etc. may be sufficient. In addition, by executing the loaded program, not only the functions of the above-described embodiment are realized, but also based on the instructions of the program, the processing is performed in cooperation with the operating system or other application programs. The functions of the invention may be realized.

  In the case of distribution in the market, the program can be stored and distributed in a portable recording medium, or transferred to a server computer connected via a network such as the Internet. In this case, the storage device of the server computer is also included in the present invention. Moreover, you may implement | achieve part or all of the mobile station apparatus 1 and the base station apparatus 3 in embodiment mentioned above typically as LSI which is an integrated circuit. Each functional block of the mobile station device 1 and the base station device 3 may be individually chipped, or a part or all of them may be integrated into a chip. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. In addition, when an integrated circuit technology that replaces LSI appears due to progress in semiconductor technology, an integrated circuit based on the technology can also be used.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the design and the like within the scope not departing from the gist of the present invention are also claimed. Included in the range.

101, 102 DMRS
105 to 111 Subcarrier 1, 1-1, 1-2 Mobile station apparatus 3 Base station apparatus 201 Reception antenna 203 Radio section 205 CP removal section 207 FFT section 209 Reference signal separation section 211 Subcarrier removal section 213 First propagation path Estimating unit 215 Channel characteristic subtracting unit 217 Second channel estimating unit 219 Signal detecting unit 221 Demodulating unit 223 Decoding unit 301, 303, 801, 1001, 1003, 1005, 1007 Subcarrier arrangement 401, 403, 405, 901 Reception Signals 501, 503, 601, 903, 905 Propagation path characteristics 701 Subcarrier extraction unit

Claims (8)

A receiving apparatus that receives a radio signal in which a plurality of reference signals having different allocation intervals of assigned subcarriers are multiplexed,
A receiving antenna that receives the radio signal in which one reference signal of the plurality of reference signals and another reference signal are multiplexed, and is assigned so that some subcarriers overlap;
A removing unit that exclude all reference signals other than the one of the reference signal from a radio signal received;
A first estimation unit for estimating the propagation path characteristics before Symbol one reference signal,
Based on the propagation path characteristics of the radio signals and one reference signal the estimated and the received reception apparatus characterized in that it comprises a second estimation unit for estimating the propagation path characteristics of the other reference signals. The receiving apparatus according to claim 1, wherein the radio signal includes a reference signal assigned to two or more consecutive subcarriers and a reference signal assigned to discretely arranged subcarriers. The radio signal is at least 2 or more clusters each composed of two or more consecutive sub-carriers, the reference signals allocated to the subcarrier is not at least one cluster is contiguous with other clusters, discrete The receiving apparatus according to claim 1, further comprising: a reference signal assigned to a subcarrier arranged in the base station.   The receiving apparatus according to claim 1, wherein the propagation path characteristic of the reference signal is estimated in ascending order of allocation intervals of the assigned subcarriers.   A wireless communication system comprising two or more mobile station devices and a base station device,
  Of the two or more mobile station devices, the first mobile station device is:
  Transmitting a first reference signal to the base station apparatus using a first subcarrier composed of two or more subcarriers;
  Of the two or more mobile station devices, a second mobile station device is:
  Transmitting a second reference signal having a different subcarrier allocation interval from the first reference signal using a second subcarrier partially overlapping with the first subcarrier;
  The base station device
  Receiving a radio signal in which at least the first reference signal and the second reference signal are multiplexed;
  Excluding all reference signals other than the first reference signal from the received radio signal;
  Estimating a propagation path characteristic of the first reference signal;
  A wireless communication system, wherein at least a propagation path characteristic of the second reference signal is estimated based on a propagation path characteristic of the received wireless signal and the estimated first reference signal.   A method of estimating a propagation path of a receiving apparatus for receiving a radio signal in which a plurality of reference signals having different allocation intervals of assigned subcarriers are multiplexed,
  Receiving the radio signal in which one reference signal and another reference signal among the plurality of reference signals, which are allocated so that some subcarriers overlap, are multiplexed;
  Excluding all reference signals other than the one reference signal from the received radio signal;
  Estimating a propagation path characteristic of the one reference signal;
  A channel estimation method including at least a step of estimating a channel characteristic of the other reference signal based on the channel characteristic of the received radio signal and the estimated one reference signal.   A control program for a receiving apparatus that receives a radio signal in which a plurality of reference signals having different allocation intervals of assigned subcarriers are multiplexed,
  A process of receiving the radio signal in which one reference signal and another reference signal are multiplexed among the plurality of reference signals assigned so that some subcarriers are overlapped;
  A process of excluding all reference signals other than the one reference signal from the received radio signal;
  A process for estimating a propagation path characteristic of the one reference signal;
  A series of processes including the process of estimating the propagation path characteristic of the other reference signal based on the propagation path characteristic of the received radio signal and the estimated one reference signal can be read and executed by a computer A control program characterized by a command.   An integrated circuit mounted on a wireless communication device,
  A function of receiving a radio signal in which one reference signal and another reference signal are multiplexed so that some subcarriers are overlapped among a plurality of reference signals having different allocation intervals of allocated subcarriers When,
  A function of excluding all reference signals other than the one reference signal from the received radio signal;
  A function of estimating a propagation path characteristic of the one reference signal;
  An integration characterized by causing a series of functions to include a function of estimating a propagation path characteristic of the other reference signal based on a propagation path characteristic of the received radio signal and the estimated one reference signal circuit.

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