JP4933141B2 - Wireless communication method and base station apparatus for wireless communication system - Google Patents

Description

  The present invention relates to a wireless communication system, more specifically, a MUI (Multi-User Interference) free access method in which signal orthogonalization is guaranteed based on repetitive transmission of a transmission signal such as CIBS-CDMA and IFDMA. The present invention relates to a radio communication method in a radio communication system and a base station apparatus thereof for reducing multi-cell interference in the radio communication system.

  In recent years, there have been proposals for MUI-free access wireless communication systems based on repeated transmission of transmission information data, such as CIBS-CDMA (Chip-Interleaved Block Spread-Code Division Multiple Access) system and IFDMA (Interleaved Frequency Division Multiple Access) system. Many have been made. These are communication systems that satisfy the complete orthogonality between orthogonal codes used during spreading processing, and have better communication quality than existing multiple access systems such as the DS-CDMA (Direct Sequence-CDMA) system in a multi-user environment. Is possible.

  According to the conventional CIBS-CDMA system, although there is no interference between users, there is a problem that it is easily affected by multipath interference. This is because inter-user interference is replaced with multi-path interference of individual users in principle by interleaving transmission data on the transmission side and deinterleaving reception data on the reception side.

In order to cope with this problem, a technique called frequency domain equalization (FDE) is used. FDE has a path diversity effect that can synthesize multipaths, and can also eliminate multipath interference, so the effect is very large, and it will be adopted in 3.5 generation mobile communications.
US Patent Publication No. 20050249269 Paper: Stefano Tomasin, Nevio Benvenuto, “Frequency-Domain Interference Cancellation and Nonlinear Equalization for CDMA Systems,” IEEE Transactions on Wireless Communications, Vol.4, No.5, September 2005

  However, in the CIBS-CDMA system, there is no interference between users only when all users are recognized in advance and orthogonal codes are assigned to the recognized users. That is, unlike a cellular environment, users of other cells or sectors cannot be grasped, and when the same user identifier is used in an adjacent cell or sector, very large interference is received. Therefore, in order to avoid this problem, always grasp the user access status of neighboring cells and sectors, change the spreading factor instantaneously and adaptively, and always orthogonalize between all users, this problem can be solved. To do.

  However, this increases the load on the host station that manages the radio access, and even if a user identifier is assigned, the propagation distance differs between the desired wave and the interference wave, and it is received with a large attenuation. In some cases, it may not be necessary to assign an excessive spreading factor. Therefore, the effect was questionable despite the wastefulness.

  Conventionally, MUD (Multi-User Detection) and interference cancellers have been proposed to eliminate these cell-sector interferences. MUDs and interference cancellers are so complex that they are unrealistic to implement and will not be described in detail, but are outlined below. The core technology of MUDs and interference cancellers is to temporarily receive and provisionally decode all users (or users with high power), remodulate them, and subtract them from the received signals that have been delayed during that time. These one-time processes are called “stages”, and it has been confirmed that the characteristics are improved in multistage.

  Also, serial processing and parallel processing are being studied. Although it can be easily analogized from the above contents, “demodulate once, remodulate and subtract from the received signal” means that terminals corresponding to the total number of accommodated users are provided in one stage. Considering the scale and processing time, even if the reception performance is improved, the implementation involves considerable difficulty.

  In order to reduce this difficulty, a proposal has been made to implement these interference cancellers and MUDs in the frequency domain. As an example, there is [Non-Patent Document 1] in the paper, and [Patent Document 1] in the patent. However, in these papers / patents, the time domain interference cancellation, which has been complicated in the past, is simply converted onto the frequency axis, and there is no improvement with respect to the complexity of performing a tentative decision or remodulating. It was. Therefore, the hardware scale is also increased, and there are still questions about its implementation.

  In summary, although FDE (frequency domain equalizer) is effective as a multipath countermeasure, it does not provide feasible interference cancellation, but has a small circuit scale that uses both interference cancellation and multipath countermeasures. There was a problem that there was no.

  The present invention has been made in view of the above, and frequency domain signal processing capable of reducing both multipath interference and interference between users from other cells and sectors (= Co-channel Interference). An object of the present invention is to provide a wireless communication method and a base station apparatus in a wireless communication system that can improve communication quality by realizing the above.

  In order to solve the above-mentioned problem, the invention described in claim 1 is configured such that a plurality of communication cells including a plurality of wireless communication terminals and a base station apparatus accommodating each wireless communication terminal are arranged, As the communication control device controls the communication state, each wireless communication terminal in each communication cell modulates and transmits a transmission signal using a unique orthogonal identifier assigned by the communication control device, and transmits a plurality of signals. In a wireless communication method for receiving the transmission signal at a base station device in the same communication cell, the base station device in each communication cell has a plurality of reception systems and is different from the communication cell. When the output from the wireless communication terminal having the same orthogonal identifier is received, a cancellation interference signal is created using the interference signal generated as a result of combining by a plurality of reception systems, and the received interference signal is received from each reception system. Respectively A first processing that support, and a second process of performing a transmission path fluctuation of the received signals of the respective receiving systems, characterized by being executable by the circuit process of the same configuration in the frequency domain.

  According to the second aspect of the present invention, each wireless communication terminal in each communication cell is configured to transmit and output including a cell identifier unique to the communication cell. Based on the cell identifier included in the output of the wireless communication terminal, a transfer function of only the interference signal for cancellation is obtained, and the first process is executed.

  According to a third aspect of the present invention, a plurality of communication cells including a plurality of radio communication terminals and a base station apparatus accommodating each radio communication terminal are arranged, and the communication control apparatus determines a communication state in each communication cell. In such a manner, each wireless communication terminal in each communication cell modulates and transmits a transmission signal using a unique orthogonal identifier assigned by the communication control apparatus, and transmits a plurality of the transmission signals to the same In the base station device in each communication cell in the radio communication method for receiving by the base station device in the communication cell, the base station device in the communication cell has a plurality of reception systems and is orthogonal identifier in another communication cell different from the communication cell. The orthogonalization processing unit that removes the received signals with different orthogonal identifiers, the frequency conversion unit that converts the output from the orthogonalization processing unit into the frequency domain, and the output from the frequency conversion unit combined in all the reception systems A frequency domain compensator that creates a cancellation interference signal using the resulting interference signal, removes it from the reception signal in each reception system, and performs transmission path fluctuation equalization on the reception signal of each reception system; It is characterized by providing.

  The invention described in claim 4 is characterized in that the frequency domain compensator is a single complex multiplier that performs interference cancellation and transmission path fluctuation equalization by linear processing in the frequency domain.

  According to a fifth aspect of the present invention, there is provided a frequency domain compensation unit using an MMSE (Minimum Mean Square Error) coefficient obtained from transfer functions of all receiving systems for an interference signal arriving from a communication cell different from the communication cell. After provisionally receiving, each transfer function of the interference signal in each reception system is given and subtracted from the reception signal of each reception system, and then received with the MMSE coefficient for the demodulated user using the transfer function of the user to be demodulated It is characterized by that.

  The invention described in claim 6 is characterized in that the processing order of the orthogonal processing unit and the frequency conversion unit is switched.

  According to the seventh aspect of the present invention, the frequency domain compensator is synthesized by a plurality of reception systems based on a cell identifier unique to the communication cell included in a transmission output from each wireless communication terminal in each communication cell. It is characterized in that it is determined whether or not it is an interference signal generated as a result.

  According to the present invention, it is possible to improve both communication quality by reducing both Co-channel interference and multipath interference. Further, according to the present invention, it is possible to reduce the required transmission power required until the radio wave reaches the receiving side, and it is possible to save power as the entire system. Furthermore, according to the present invention, it is possible to increase the spreading factor in anticipation of the presence of users in other cells / sectors in advance, that is, to perform communication without causing a decrease in transmission rate.

  Next, embodiments of a radio communication method and its base station apparatus in a radio communication system according to the present invention will be described in detail with reference to the accompanying drawings. Prior to that, in order to clarify the essential points of the present invention, Describe the differences.

  FIG. 8 shows an example of system operation by the CIBS-CDMA system in the prior art. That is, in FIG. 8, two cells consisting of A and B are described, and in Cell-A, two users (MS # 0-A, MS # 1-A), which are wireless communication terminals MS such as portable terminals, In addition, one user (MS # 0-B) is connected to Cell-B, and is communicating with the base station apparatus. When limited to Cell-A, User # 0 (MS # 0-A) and User # 1 (MS # 1-A) are assigned different orthogonal codes, so they are shown as 0205 to 0212. In such a base station apparatus, orthogonalization of these users can be realized without problems.

  Here, the wireless communication terminal includes a transmission data generating unit 0201, a multiplier 0202, an interleaver 0203, a guard interval adding unit 0204, and a transmission / reception wireless unit TRX0205. The transmission data generation unit 0201 is a block that generates data such as independent voices and images. The multiplier 0202 is a spread spectrum unit that provides an orthogonal variable spreading factor (OVSF) code that is an orthogonal identifier (hereinafter also referred to as a user identifier) that is also used in the current third generation wireless communication.

  The interleaver 0203 changes the transmission order of transmission signals unique to the CIBS-CDMA communication system. A guard interval giving unit 0204 is a guard interval (GI) giving unit for reducing an aperture effect that occurs when a time signal discontinuous in the frequency domain is converted into the frequency domain. A transmission / reception radio unit (TRX) 0205 is a transmission / reception radio unit having an analog unit such as a D / A, A / D converter, frequency conversion unit, orthogonal modulation / demodulation unit. Actually, the configuration of the transmission / reception radio unit 0205 is slightly different between the base station apparatus and the wireless communication terminal, but since the functions are almost the same, here, the same reference numerals are given to the wireless communication terminal and the base station apparatus.

  The base station apparatus includes a guard interval removal unit 0206, a deinterleaver 0207, a multiplier 0208, an integrator 0209, an FFT0210, a complex multiplier 0211, and an iFFT0212. The guard interval removing unit 0206 is a circuit that extracts the guard interval inserted by the guard interval providing unit 0204. The deinterleaver 0207 is a circuit that performs reverse processing of the interleaver 0203 on the transmission side and converts it to the original signal order.

  Multiplier 0208 is a multiplier that performs spectrum despreading, and is a user orthogonalization processing unit that identifies a desired signal based on the user identifier assigned by multiplier 0202 of the wireless communication terminal. The integrator 0209 is an integrator that performs spectrum despreading, and performs interval integration of one cycle (= spreading factor) of OVSF. FFT0210 and iFFT0212 are a time / frequency converter for converting to the frequency domain and a frequency / time converter for converting to the time domain, respectively. Multiplier 0211 is a complex multiplier.

  In FIG. 8, the user identifier OVSF # 0 used in Cell-A is assigned to the radio communication terminal MS # 0-B of Cell-B. Therefore, although the radio communication terminal MS # 0-B is communicating with the base station apparatus B, if the radio wave also arrives at the base station apparatus A (= may not arrive), it becomes an interference source. On the other hand, in a general MUI free access scheme such as CIBS-CDMA and IFDMA, interference does not occur due to the orthogonalization principle if the user identifier is different. Therefore, although MS # 0-B is an interference source for radio communication terminal MS # 0-A, MS # 0-B has an orthogonal user identifier for MS # 1-A. It will not be a source of interference.

  However, this orthogonalization principle is not effective when despreading is performed after frequency domain equalization or interference cancellation as described in Patent Document 1, or when determination is made in the frequency domain. This is because the multiplication process in the frequency domain corresponds to the convolution integral on the time axis. In other words, the optimum multipath removal coefficient for a certain user on the frequency axis is equivalent to the addition of an unrelated multipath when viewed from other user signals. As a result, the interference power is dispersed. This means that the state is close to noise and close to a state where interference cannot be removed. This is shown by an expression in the frequency domain expression.

Now, consider a case of receiving a transmission signal X _D of the desired user in the base station apparatus. Via the multi-path propagation paths indicated by H _D, noise n is added, the base station apparatus receives signals Y _D is as the following equation (1). Since the following mathematical expressions are all functions on the frequency axis, the suffix “(ω)” should be added as shown in FIG.
Y _D = H _D X _D + n… (1)

Against the received signal and performs frequency domain equalization to equalize the multipath H _D. When Zero Forcing equalization is taken into account, the equalization weight is given by the following equation (2).
W _D = 1 / H _D (or H _D * / | H _D | ² ) ... ZF weight… (2)
Here, * is a complex conjugate, and || is an absolute value. In addition, considering that | x | ² = xx *, it can be understood that the contents indicated by or in the above equation are the same. By multiplying this weight to the received signal Y _D, as shown in equation (3),
Y _D W _D = X _D + n / H _D … (3)
It can be seen that the transmission information _XD is not affected by multipath. On the other hand, a multipath effect is given to the noise component.

Now, consider the interference signal X _I. Interference source is considered a different location than the desired signal, also when to have an independent multipath H _I, the base station apparatus receives signals Y, as shown in equation (4),
Y = H _D X _D + H _I X _I + n… (4)
It is expressed. Here, by multiplying the weight W _D represented by the equation (2) in order to receive the desired signal, YW _D, as shown in Equation (5),
YW _D = X _D + (H _I H _D / | H _D | ² ) X _I + nH _D / | H _D | ² … (5)
It can be seen that although the desired signal can be extracted as desired, the interference component X _I remains.

Interference signal, the multipath environment of the original H _I from its coefficients, further, it is seen that the multi-path environment where H _D is superimposed. Further, since the H _D and H _I not complex conjugate form, rather than reduce multipath must also be noted that are newly generated. Therefore, the interference signal in terms of, new multipath is formed by multiplication of H _D can be considered to be spread in the time domain.

That is, since energy is dispersed, the interference signal level per multipath is lowered. As is clear from equation (5), in Patent Document 1, provisional determination is used to reduce this residual interference. As a result, the right side in Equation (5) becomes X _D ^′ , and the interference term and noise term are deleted to some extent. Thereafter, if H _D X _D ′ is subtracted from the delayed received signal, the interference for the interference user, that is, the desired signal is deleted. It can be easily imagined that the accuracy will gradually improve if this operation is repeated.

  In other words, the provisional determination described above is indispensable for improving the performance, and the concept of multistage is essential for improving the accuracy of the provisional determination and thus improving the overall reception quality. Therefore, the prior art inevitably requires a large-scale hardware, and has practically no feasibility.

On the other hand, the present invention is premised on application to MUI-Free access, and the total number of users is limited in the previous stage of equalization / interference removal. As a result, the number of interfering users shown in the above equation (5) can be limited (in equation (5), there was only one interfering user to assist understanding, but H _I1 X _I1 , H _I2 X _I2 , H Increasing _I3 X _I3 , ... will result in multi-interference users). Since user orthogonalization is performed at the stage before equalization and interference cancellation, only interference users having the same user identifier (for example, OVSF code) as the desired user remain in Equation (5).

  As a result, in order to handle signals of all users assumed in the prior art (in the prior art shown in FIG. 8, the base station apparatus transmits / receives a user # to and from one wireless communication terminal in order to remove the influence of user interference. It is necessary to include a large number of virtual terminals in one stage. On the other hand, in the configuration of the present invention, the circuit scale can be greatly reduced, and the circuit scale can be realized.

  Further, the interference signal extraction accuracy is improved by the diversity effect by providing a plurality of receiving systems. Thus, if the accuracy of the interference signal is improved by limiting the number of interfering users and the diversity configuration, it is possible to suppress the reception quality deterioration to some extent without using provisional determination. As a result, circuit scale reduction, which is an important subject of the present invention which is not shown in Patent Document 1, can be realized.

  Next, the first main point of the present embodiment will be described with reference to FIG. 2, but this diagram is only for explaining the first main point and does not show the configuration of the present embodiment. FIG. 2A shows a situation where one interfering user is canceled. By bringing the user orthogonalization processing unit 0101 (multiplier 0208 in FIG. 8) to the previous stage, interference other than the same user identifier can be obtained. The user's interference signal is removed.

  That is, in FIG. 2 (A), a user orthogonalization processing unit 0101 is connected to a subsequent stage of a transmission / reception radio unit (not shown) corresponding to the transmission / reception radio unit TRX0205 of FIG. Section FFT0102 is connected. As described above, the time / frequency conversion unit FFT0102 is provided so that the subsequent processing can be performed on the frequency axis.

With such a configuration, the received output signal Y (ω) from the time / frequency conversion unit FFT0102 becomes a signal of only the same user identifier, which is output to the adder 0103 and output to the multiplier 0109, thereby causing interference. The MMSE weight W _I (ω) for the user is integrated. A multiplier 0112 is connected to the output side of the multiplier 0109, and the transfer function H _I (ω) of the interference user is added to the output of the multiplier 0109 and output to the adder 0103. The adder 0103 outputs an output signal Y (ω) ′ obtained by subtracting the signal output from the multiplier 0112 from the output signal Y (ω) from the time / frequency conversion unit FFT0102 to the multiplier 0104. The multiplier 0104 outputs the output signal Y (ω) ′ to the frequency / time conversion unit iFFT0115 that converts the FDE output obtained by integrating the MMSE weights W _D (ω) for the desired user into the time domain.

In FIG. 2, unlike the prior art (Patent Document 1), since provisional determination is not performed, the interference component (= desired signal) and noise for the interference user are subtracted from the delayed transmission / reception signal as it is. This situation will be described using equations. The received signal Y is expressed by the aforementioned equation (4). On the other hand, the received signal Y after the interference signal is subtracted ', as shown in FIG. 2 (A), a multiplier 0109 and 0112 and by W _I and H _I and the received accumulated signal to the reception signal Y Since it is subtracted from the signal Y by the adder 0103, the equation (6) shows:
Y '= Y-W _I H _I Y
= Y (1-W _I H _I )… (6)
It becomes.

  Next, referring to FIGS. 2 (A) and 2 (B), the effect of the “equipment of a plurality of receiving systems” which is the second main point of the present invention will be described. FIG. 2A is a conceptual diagram when interference cancellation is described when there is only one receiving system. FIG. 2B is a circuit (adder 0103, multiplier 0109, and multiplier 0112) that performs interference cancellation. ) Is an example of the configuration without the above.

Hereinafter, it is shown by a mathematical formula that FIG. 2 (A) and FIG. 2 (B) match. The signal of the desired user signal X _D interfering users and X _I, the transfer function of the transmission path respectively and H _D, H _I. In addition, the MMSE weight for the desired user when there is no interference signal is W _D , and the MMSE weight for the interference signal is W _I. When the desired signal-to-noise power ratio is SNR _D and the interference signal-to-noise power ratio is SNR _I , the relationship of the following equation (7) with respect to the received signal Y is shown.
Y = H _D X _D + H _I X _I + n
W _D = H _D * / (| H _D | ² + SNR _D ^-1 )
W _I = H _I * / (| H _I | ² + SNR _I ^-1 )… (7)
Here, || represents an absolute value and * represents a complex conjugate. The reception signal Y obtained by these transfer functions and noise power, the MMSE weight W _D, is calculated by the coefficient generation unit without the MMSE weight W _I is shown, the frequency compensation portion of the receiver shown in FIG. 1 described later Used as a coefficient.

When FIG. 2A is faithfully expressed, the FDE output is as shown in Expression (8),
FDE output = W _D (Y-H _I W _I Y)
= W _D Y (1-H _I W _I )
= W _D Y (1-| H _I | ² / (| H _I | ² + SNR _I ^-1 ))… (8)
Which coincides with the coefficients in FIG.

However, it can be seen that the above equation does not make sense as interference cancellation. This is because when the SNR, which is the signal power ratio to the noise power ratio, is very high, it is regarded as SNR _I ⁻¹ = 0, and the FDE output becomes zero after all.

  Here, in this embodiment, this problem is avoided by providing a plurality of receiving systems. Assuming that two branches (= 2 reception systems) are received, the interference signal for branch 1 is constructed using the interference signal for branch 2, and similarly, the interference signal for branch 2 is the interference signal for branch 1. Use to build. As a result, it is possible to avoid a situation in which the extraction of the interference signal fails and the reception signal becomes 0 as shown in FIGS.

  In other words, by combining the interference canceller, the diversity reception, and the frequency domain equalizer, which are well-known techniques, with the careful consideration, the same hardware scale as that of the conventional frequency domain equalizer (= one complex multiplier as an optimal configuration example) ) Only, interference removal and desired wave equalization can be performed simultaneously.

  Next, before describing the receiver in this embodiment, data orthogonalization based on repetitive transmission of transmission data such as CIBS-CDMA system and IFDMA system to which the present invention is applied is guaranteed and the user A configuration example of a MUI free access wireless communication system capable of reducing the number of candidates will be described with reference to FIG.

  The communication control device 10 is a control device that controls a communication state in each communication cell of the base station device BS14 (A to G), and is a cell (C-A to C) that is a range of radio waves of each base station device BS14. -G) A unique orthogonal identifier is allocated to the radio communication terminals MS20-001 to 20-013 moving in the area. Each base station apparatus BS is a base station whose receiver is configured as shown in FIG. 1 to be described later, and the radio communication terminal MS20 in the cell under management by the orthogonal identifier assigned by the communication control apparatus. Has been identified. Radio communication terminal MS20 is a mobile terminal having the same configuration as radio communication terminal MS20 shown in FIG. 8, which modulates and transmits a transmission signal using an orthogonal identifier assigned to the communication control apparatus.

  FIG. 1 is a configuration diagram of a receiver in the present embodiment of the base station apparatus BS14 shown in FIG. 9, and the embodiment of the base station apparatus according to the present invention will be described in detail with reference to FIG. FIG. 1A shows an interference removal and equalization circuit equivalent to the configuration of this embodiment. The difference from FIG. 2 is that interference signals are extracted by using a diversity antenna of two receiving systems. Each receiving system has the same configuration, and finally the received signals in these receiving systems. Are added by the adder 0114, and the FDE output is output to the frequency / time conversion unit iFFT0115.

  Therefore, the user orthogonal circuit 0105 is the user orthogonal circuit 0101, the time / frequency conversion unit FFT0106 is the time / frequency conversion unit FFT0102, the adder 0107 is the adder 0103, the multiplier 0108 is the multiplier 0104, and the multiplier 0110 is The multiplier 0109 and the multiplier 0113 have the same functions as the multiplier 0112, respectively. The outputs of the multiplier 0109 and the multiplier 0110 are added by the adder 0111, and the output is output to the multiplier 0112 and the multiplier 0113. Further, the output of the multiplier 0112 is output to the adder 0103, and the output of the multiplier 0113 is output to the adder 0107.

These signals are subtracted from the received signals Y ₁ (ω) and Y ₂ (ω) output from the time / frequency converters FFT0102 and FFT0106 and output to the multipliers 0104 and 0108. These multipliers 0109, 0110, adder 0111, multipliers 0112, 0113, adders 0103, 0107, and multipliers 0104, 0108 perform interference cancellation using the interference signals of all reception systems and A frequency domain compensator for performing transmission line equalization is formed.

Now, there is one interfering user, the transfer function of the interfering user is H _Ix (ω) (x is the antenna number), the MMSE weight for the interfering user is W _Ix (ω), and the desired user is the one with the transfer function H _{Let Dx} (ω) and the MMSE weight be W _Dx (ω). When expressed mathematically faithfully to the configuration of FIG. 1A, the FDE output is as shown in equation (9):
FDE output =
W _D1 {Y ₁ -H _I1 (W _I1 Y ₁ + W _I2 Y ₂ )}
+ W _D2 {Y ₂ -H _I2 (W _I1 Y ₁ + W _I2 Y ₂ )}
= {W _D1 -H _I1 W _I1 W _D1 -W _D2 H _I2 W _I1 } Y ₁
+ {W _D2 -H _I2 W _I2 W _D2 -W _D1 H _I1 W _I2 } Y ₂
= {W _D1 -W _I1 (W _D1 H _I1 + W _D2 H _I2 )} Y ₁
+ {W _D2 -W _I2 (W _D1 H _I1 + W _D2 H _I2 )} Y ₂ … (9)
This is consistent with FIG.

It is confirmed whether the same problem as in FIG. 2 does not occur (that is, whether a complete no-signal state due to cancellation can be avoided). Here, although the demodulation characteristics of MMSE are optimal, the analysis includes trouble because the noise power term is included in the coefficient. Here, for the purpose of examining the influence of the interference term, the calculation is performed while ignoring the noise term. In this case, W _I1 and W _I2 in the above equation are H _I1 ^* / α and H _I2 ^* / α (where α = | H _I1 | ² + | H _I2 | ² ), respectively. Substituting and calculating, the following formula (10) is obtained:
FDE output = {W _D1- (H _I1 ^* / α) (W _D1 H _I1 + W _D2 H _I2 )} Y ₁
+ {W _D2- (H _I2 ^* / α) (W _D1 H _I1 + W _D2 H _I2 )} Y ₂
= {W _D1- (H _I1 ^* / α) (W _D1 H _I1 + W _D2 H _I2 )} (H _D1 X _D + H _I1 X _I + n ₁ )
+ {W _D2- (H _I2 ^* / α) (W _D1 H _I1 + W _D2 H _I2 )} (H _D2 X _D + H _I2 X _I + n ₂ )
… (Ten)

If this is rearranged as A = W _D1 H _I1 + W _D2 H _I2 , it is shown in the following formula (11),
= {W _D1- (H _I1 ^* / α) A} (H _D1 X _D + H _I1 X _I + n ₁ )
+ {W _D2- (H _I2 ^* / α) A} (H _D2 X _D + H _I2 X _I + n ₂ )… (11)
become.

To summarize the interference signal X _I , as shown in equation (12),
X _I coefficient = W _D1 H _I1- | H _I1 | ² / αA + W _D2 H _I2- | H _I2 | ² / αA
= W _D1 H _I1 + W _D2 H _I2 -A (| H _I1 | ² + | H _I2 | ² ) / α
= W _D1 H _I1 + W _D2 H _I2 -A
= 0… (12)
It becomes.

  As described above, when such a Zero Forcing coefficient is used, although the interference term becomes 0, a noise enhancement problem occurs and the demodulation characteristic is deteriorated as compared with MMSE. Therefore, the preferred embodiment is the use of MMSE coefficients. However, the above equation shows that the interference term can be zero in principle.

The desired the signal X _D, and rearranging, as shown in the following (13),
X _D coefficient = W _D1 H _D1 -H _D1 (H _I1 ^* / α) A + W _D2 H _D2 -H _D2 (H _I2 ^* / α) A
= W _D1 H _D1 + W _D2 H _D2 -A (H _D1 H _I1 ^* + H _D2 H _I2 ^* ) / α… (13)

Here, W _D1 and W _D2 are respectively H _D1 ^* / β and H _D2 ^* / β (where β = | H _D1 | ² + | H _D2 | ² ) and put it as shown in equation (14)
= 1-A (H _D1 H _I1 ^* + H _D2 H _I2 ^* ) / α
= {αβ-| H _D1 ^* H _I1 + H _D2 ^* H _I2 | ² } / (αβ)
= {Α (| H _D1 | ² + | H _D2 | ² )
-| H _D1 | ² | H _I1 | ^2- | H _D2 | ² | H _I2 | ² -H _D1 ^* H _I1 H _D2 ^* H _I2 -H _D1 H _I1 ^* H _D2 H _I2 ^* }
^{_{= {| H D1 | 2 |}} H I1 | 2 + | H D2 | 2 | H I2 | 2 + | H D1 | 2 | H I2 | 2 + | H D2 | 2 | H I1 | 2
-| H _D1 | ² | H _I1 | ^2- | H _D2 | ² | H _I2 | ² -H _D1 ^* H _I1 H _D2 ^* H _I2 -H _D1 H _I1 ^* H _D2 H _I2 ^* }
= {| H _D1 | ² | H _I2 | ² + | H _D2 | ² | H _I1 | ² -H _D1 ^* H _I1 H _D2 ^* H _I2 -H _D1 H _I1 ^* H _D2 H _I2 ^* }
= {| H _D1 ^* H _I2 -H _D2 H _I1 ^* | ² }… (14)
It becomes.

  From this, it can be seen that all the signals that were a problem in the previous one-branch reception are not canceled out. This indicates that, assuming a plurality of reception systems, each branch signal is mixed and it is possible to avoid cancellation.

  From the above, as disclosed in the present embodiment, first, the users are orthogonalized in each of the plurality of reception systems, and then interference signals are generated from the plurality of reception systems, and subtracted from the delayed reception signals, respectively. Thus, it has been shown that the frequency domain compensator for performing interference cancellation and transmission path equalization can be realized by one complex multiplier.

  As described above, if the transfer function of the interference signal is known, a linear interference canceller can be constructed by devising the weight generation method. However, in order to reduce the load of weight generation, the smaller the number of interference signal sources, the better. It is clear. Therefore, a user orthogonalization process (user orthogonalization processing units 0101 and 0105 in FIG. 1) is arranged before this interference canceller operation to limit the number of users.

  The effect of the CIBS-CDMA system according to this embodiment was confirmed by computer simulation. FIG. 4 and FIG. 5 show the error rate (BER: Bit Error Rate) characteristics. FIG. 4 is an error rate characteristic diagram showing the interference cancellation performance in the two reception systems as shown in FIG. 1, and FIG. 5 is an error rate characteristic diagram showing the interference cancellation performance in the four reception systems. The transmission line model is a 6-pass exponentially damped static environment. It is assumed that one desired user and one interfering user exist near the cell or sector boundary, and the transmission path between the users is independent, but is received by the base station apparatus with equal power.

  In order to make it easier to compare with 4-branch reception, the characteristics at the time of 2-branch reception are shifted left by 3 dB so that the horizontal axes match. In addition, FDE-MMSE in the figure is the BER characteristic when interference cancellation performance is not provided, and 1-stage FDE-IC is the one in this embodiment when 1-stage interference cancellation / equalization is performed. BER characteristics. 2-stage and 3-stage will be described later. The w / o CCI indicates the BER characteristic when there is no interference, and the solid line QPSK Theory indicates the BER characteristic based on a theoretical value.

The number of multipliers in the FDE is one in each case (when operating at the sample rate or chip rate). 4 and 5, it can be seen that the reception characteristics are greatly improved in the same hardware as compared with the case where interference cancellation is not performed. That is, in any case in the FDE-MMSE, in the present embodiment, two branches are used in spite of the fact that an area where one error occurs (BER = 10 ⁻² ) cannot be achieved in 100 transmission data bits. It can be seen that it was achieved except for 1-stage. In addition, as described above, since this embodiment generates an interference signal in consideration of other branch signals, the reception performance is improved by increasing the number of branches (from 2 branches to 4 branches).

In addition, if the FDE multiplication coefficient used in the computer simulation is expressed by a mathematical expression, it is as shown in the following expressions (15) to (21), respectively.
During 2 branches:
Coefficient for branch 1: W _D1 -W _I1 (W _D1 H _I1 + W _D2 H _I2 )… (15)
Coefficient for branch 2: W _D2 -W _I2 (W _D1 H _I1 + W _D2 H _I2 )… (16)
4 branches:
Coefficient for branch 1: W _D1 -W _I1 (W _D1 H _I1 + W _D2 H _I2 + W _D3 H _I3 + W _D4 H _I4 )
… (17)
Coefficient for branch 2: W _D2 -W _I2 (W _D1 H _I1 + W _D2 H _I2 + W _D3 H _I3 + W _D4 H _I4 )
… (18)
Coefficient for branch 3: W _D3 -W _I3 (W _D1 H _I1 + W _D2 H _I2 + W _D3 H _I3 + W _D4 H _I4 )
… (19)
Coefficient for branch 4: W _D4 -W _I4 (W _D1 H _I1 + W _D2 H _I2 + W _D3 H _I3 + W _D4 H _I4 )
… (20)

ここで、W_Dx、W_Ix、H_Dx、H_Ixとは、先の数式説明に用いたものと同一であり、それぞれ、希望信号のMMSEウェイト、干渉信号のMMSEウェイト、希望信号の伝達関数、干渉信号の伝達関数であり、ｘはアンテナ番号、つまり受信系統番号である。

Here, W _Dx , W _Ix , H _Dx , and H _Ix are the same as those used in the previous mathematical description, and the MMSE weight of the desired signal, the MMSE weight of the interference signal, the transfer function of the desired signal, It is a transfer function of an interference signal, and x is an antenna number, that is, a reception system number.

  In such a configuration, in the present embodiment, the total number of users is limited before the interference removal / equalization is performed, and the transfer function of each interference user is detected and removed, and the transfer function of the desired signal is detected. Then, interference removal / equalization processing is performed.

  According to such an interference cancellation / equalization method, interference cancellation is performed on the interference signal using the same user identifier by performing complex multiplication processing on the reception data in the frequency domain on the reception side, so that the desired user can be prevented. On the other hand, multipath interference in a multipath environment can be equalized. Further, since it is a linear process, interference removal and equalization is performed with only one complex multiplier in the most preferable example, and an increase in hardware scale does not occur.

  Therefore, by applying the interference cancellation / equalization method according to the present embodiment, high-speed performance is reduced due to the presence of interference users that occur rarely in an extremely short time (for example, 0.5 msec), such as high-speed packet transmission. Without sacrificing (= increasing the spreading factor), and when there are no interfering users, the same MMSE equalization as before can be performed, so the transmission rate is lower than the conventional wireless communication method. It is not necessary, and the communication quality can be greatly improved.

  And by improving communication quality in this way, it becomes possible to reduce the required transmission power required until the radio wave reaches the receiving side. This means that the battery of the mobile communication terminal can be kept for a long time when considering the uplink from the mobile communication terminal to the base station apparatus, and that the power saving of the infrastructure equipment can be achieved when considering the downlink. . Further, if the application does not particularly require power saving, it means that the radio wave reach is extended accordingly, and in any case, an effective effect can be obtained.

  Next, an embodiment of a transmitter in the wireless communication system according to the present invention will be described. In the embodiment shown in FIG. 1, the case where the transfer function of the interfering user is obtained by some means has been described in detail. In this embodiment, the cell / sector identifier is transmitted together with the transmission signal from the transmitter of the radio communication terminal MS20 in FIG. 9, so that the frequency domain compensator of the receiver of the base station apparatus 14 can identify the interference user. Show.

  FIG. 6 shows an example of the configuration of the transmitter in this embodiment. In FIG. 6, a pilot signal generation unit 1001 is a generation unit that generates a pilot signal that is a pseudo noise code such as an M-sequence, and outputs the generated pilot signal to the identifier assigning unit 1002. The identifier assigning unit 1002 is a multiplier that assigns, to the pilot signal, a cell / sector identifier that is a cell identifier unique to the communication cell of the base station apparatus that performs communication. The identifier assigning unit 1002 may be an ExOR or complex multiplier in addition to the multiplier. The transmission data generation unit 0201 is a block that generates data such as independent voices and images.

  The changeover switch 1003 is a switch that switches transmission data from the transmission data generation unit and a cell / sector identifier from the identifier assigning unit 1002 at a predetermined timing, and outputs these data to the multiplier 0202 as a spread spectrum unit. A multiplier 0202 is a multiplier that provides a spreading code (OVSF code) that is a user identifier. The multiplier 0202 is connected to the interleaver 0203, and the transmission data to which the OVSF code is added is output to the interleaver 0203. The interleaver 0203 changes the transmission order of transmission signals specific to the CIBS-CDMA communication system.

  The interleaver 0203 is connected to the guard interval assigning unit 0204, and a transmission signal whose transmission order is changed is output thereto. The guard interval giving unit 0204 is a giving unit that gives a guard interval (GI) for reducing an aperture effect that occurs when a time signal discontinuous in the frequency domain is converted into the frequency domain. The guard interval giving unit 0204 is connected to the transmission / reception radio unit TRX0205 and outputs a transmission signal to which a guard interval is given. The transmission / reception radio unit TRX0205 is a transmission / reception unit having an analog unit such as a D / A, A / D converter, frequency conversion unit, orthogonal modulation / demodulation unit.

  As described above, also in the case of the transmitter shown in FIG. 6, a user identifier for each connected user is assigned, and a pilot signal that is a known signal, such as an M sequence that is a random periodic sequence, exists between the transceivers. To do. Then, a cell / sector identifier assigned to a cell or sector is given to the pilot signal, a user identifier is given in the same manner as a normal data signal, and these are transmitted prior to a transmission data sequence, for example.

  On the receiving side, user orthogonalization is performed using user identifiers, and then correlation reception using pilot signals is performed, for example, a section that is an integral multiple of the pilot signal period (= M sequence period), and then multiplied by each cell / sector identifier. By accumulating, it is recognized whether it is the same cell / sector or a different cell / sector.

  This is shown in FIG. 7A is a diagram obtained by despreading using a spreading code common to all users, FIG. 7B is a diagram obtained by adding the desired user cell / sector identification code (++), and FIG. 7C is an interfering user cell. Each figure shows addition with the sector identification code (+-).

  FIG. 7A shows an MF (Matched Filter) output for a pilot signal (for example, M sequence) common to users in the receiver. A pseudo-noise code with sharp autocorrelation such as an M sequence outputs a correlation result as shown in FIG. As a more specific example, an M sequence consisting of 64 chips (a chip indicates an M sequence 1-bit unit) (strictly, an M sequence can only have an odd number, but this time is an example, so 0 is added. ) Is a pilot signal, and this M sequence is given to the coefficient of MF.

  When the received signal is supplied to, for example, 128 chips (two correlation windows of 64 chips), the output of two M-sequence periods is obtained. At this point, not only the desired user but also the correlation output of the Co-Channel interfering user appears, so the two cannot be distinguished. However, since the cell / sector identifier exists, for example, if the cell identifier of the desired user is +1, +1, and the cell / sector identifier of the interfering user is +1, -1, each of the 64 chip sections is added. The impulse response of the transmission path of the desired user cell shown in FIG.

Similarly, when +1 and -1 are multiplied and accumulated, the impulse response of the interfering user shown in FIG. 11C is obtained. If these results are frequency-converted, H _I and H _D , and thus W _I and W _D in the previous equation can be obtained. When there are many Co-Channel interference users, the cell / sector identifier is 2 chips in the previous example, but it may be increased to 4 chips or 8 chips.

  Therefore, by applying the transmission method according to this embodiment, not only the desired user but also the transfer function of the interfering user can be obtained. From this, it is possible to perform interference removal of the interference user and equalization of the desired signal, so that the communication quality can be greatly improved as compared with the conventional wireless communication system, and power saving can be achieved.

  In the embodiment of the transmitter, in order to simplify hardware for initial synchronization (= including user detection), it is assumed that all users have a common pilot signal (= may be called a synchronization channel). explained. If the premise of this hardware simplification is removed, a different pilot signal such as a general orthogonal Gold code or M sequence may be given to each user. In this case, an initial synchronization detection unit for the Gold code or M sequence is required on the receiving side, but the present invention can be applied.

  Next, another embodiment of the base station apparatus according to the present invention will be described. In the embodiment shown in FIG. 1, the case of one stage of subtracting the interference user from the signal of the desired user has been described in detail. In the embodiment of FIG. 3, the embodiment when it is multistaged will be described.

  FIGS. 3A and 3B show the configuration of an interference cancellation and equalization circuit according to another embodiment of the receiver applied to the base station apparatus BS14 of FIG. The multi-stage configuration according to this embodiment will be described in comparison with FIG. 1A showing the concept of a single stage.

  3A differs from FIG. 1A in that the Stage 2 portion is clearly introduced, and the configuration of the third embodiment is a two-multistage configuration. Note that if Stage1 and Stage2 do not exist, that is, only Stage0, this corresponds to MMSE reception equalization without performing interference cancellation.

  In FIG. 3, in order to receive a desired signal, an interference signal is generated in Stage 1 and subtraction is performed from the original received signal. As a matter of course, the desired signal corresponds to the interference signal for the interference signal extraction. Therefore, by extracting the desired signal at Stage 2 and subtracting it from the received signal for interference extraction, the accuracy of interference signal extraction at Stage 1 is improved. This is the basic concept of multistage.

As a matter of course, when extracting the interference signal (or extracting the desired signal), the extraction accuracy improves as the received power increases. Therefore, it is apparent that the performance improvement of the final desired signal can be obtained by performing signal extraction in the order of the received power, not in the order shown in FIG. 3A.
Now, the multiplication coefficient at the time of multistage will be proved by a mathematical formula.

When expressed mathematically faithfully to the configuration of FIG. 3A, the FDE output is as shown in Expression (22),
FDE output =
W _D1 (Y ₁ -H _I1 (W _I1 (Y ₁ -H _D1 (W _D1 Y ₁ + W _D2 Y ₂ ) + W _I2 (Y ₂ -H _D2 (W _D1 Y ₁ + W _D2 Y ₂ ))) ]
+ W _D2 (Y ₂ -H _I2 (W _I1 (Y ₁ -H _D1 (W _D1 Y ₁ + W _D2 Y ₂ ) + W _I2 (Y ₂ -H _D2 (W _D1 Y ₁ + W _D2 Y ₂ )) )] …(twenty two)
It becomes.

The value in [] is calculated first by the following equation (23).
[] =
W _I1 (Y ₁ -H _D1 (W _D1 Y ₁ + W _D2 Y ₂ ) + W _I2 (Y ₂ -H _D2 (W _D1 Y ₁ + W _D2 Y ₂ ))
= {W _I1 -W _I1 H _D1 W _{D1 -} W _I2 H _D2 W _{D1 }} Y ₁ + {W _I2 -W _I1 H _D1 W _D2 -W _I2 H _D2 W _{D2 }} Y ₂
= {W _I1 -W _D1 (H _D1 W _I1 + W _I2 H _D2 )} Y ₁ + {W _I2 -W _D2 (H _D1 W _I1 + W _I2 H _D2 )} Y ₂
= {W _I1 -W _D1 B} Y ₁ + {W _I2 -W _D2 B} Y ₂ … (23)
Here, B = W _I1 H _D1 + W _I2 H _D2 .

Substituting this result into the FDE output yields equation (24).
FDE output =
W _D1 {Y ₁ -H _I1 [(W _I1 -W _D1 B) Y ₁ + (W _I2 -W _D2 B) Y ₂ ]}
+ W _D2 {Y ₂ -H _I2 [(W _I1 -W _D1 B) Y ₁ + (W _I2 -W _D2 B) Y ₂ ]}
= {W _D1 -W _D1 H _I1 (W _I1 -W _D1 B) − W _D2 H _I2 (W _I1 -W _D1 B)} Y ₁
+ {W _D2 -W _D1 H _I1 (W _I2 -W _D2 B) − W _D2 H _I2 (W _I2 -W _D2 B)} Y ₂ … (24)

By the way, in the result of the previous SingleStage, A = W _D1 H _I1 + W _D2 H _I2 was used, so when introduced again here, as in the following equation (25),
= {W _D1 − A (W _I1 -W _D1 B)} Y ₁
+ {W _D2 − A (W _I2 -W _D2 B)} Y ₂ (Stage2: Coefficient)… (25)
become.

Extending this idea and considering up to stage 3, as shown in the following formula (26),
= {W _D1 − A [W _I1 − B (W _D1 −AW _I1 )]} Y ₁
+ {W _D2 − A [W _I2 − B (W _D2 −AW _I2 )]} Y ₂ (Stage 3: coefficient)… (26)
It becomes. Further, when the number of reception systems fluctuates, as described in the description of the preceding claims, the number of terms A and B described above may be increased together.

  Note that the present invention is not limited to the above-described embodiment, and variations or modifications of the technical idea equivalent to the present invention are included in the scope of the present invention. That is, in the first embodiment described above, the user orthogonalization process is performed before the frequency conversion process, but these are linear operations, and there is no problem even if the order is changed.

  Further, in the above-described embodiment of the receiver of the base station apparatus, the case where the present invention is applied to the CIBS-CDMA system has been described. However, the present invention is not limited to this, and the point is that between users Various other radios that use orthogonal communication methods that can reduce the number of user candidates for interference cancellation, such as IFDMA (Interleaved Frequency Domain Multiple Access) and VSCRF-CDMA (Variable Spreading Chip Repetition Factor-CDMA) It can be widely applied to any wireless communication system that uses high-speed packet transmission that allocates a very short time to each user by the communication method or the upper scheduling function and reduces inter-channel interference with other cells and sectors. .

  Further, in the above-described transmitter embodiment, the pilot signal is a preamble scheme generally called, but there is no problem in any form such as midamble and postamble. Moreover, although the example applied to the transmitter of the radio communication terminal has been described in the embodiment of the transmitter, it can also be applied to the transmitter of the base station apparatus BS14. Further, each of the above-described receiver embodiments is not limited to the base station apparatus BS14, and can be applied to any wireless communication terminal such as a mobile computer in which a diversity antenna can be mounted. Therefore, if the above-described embodiment of the present invention is applied to each of the base station apparatus BS14 and the radio communication terminal, an excellent radio communication system capable of improving the call quality and reducing the transmission power can be realized with a large-scale circuit. It can be realized without using it.

  In the embodiment of the receiver shown in FIG. 3, the concept of multi-stage is introduced. Generally, when multi-stage is used, the stage suppression coefficient is 1 rather than subtracting 100% of a removal signal including an error. It is also possible to introduce a technique of multiplying by a small value and operating so as not to pull too much. In the computer simulations shown in FIGS. 4 and 5, the suppression coefficient is actually introduced. A general MMSE coefficient has a noise power term in the denominator. Therefore, the output signal after frequency domain equalization may be smaller than the original value. In this case, if the “suppression coefficient smaller than 1” described above is not greater than 1, the level deviates from that to be subtracted and needs to be corrected.

  As described above in detail, in the frequency domain equalization / interference removal method in the receiver of the present invention, the orthogonal identifier unique to the wireless communication device assigned to each transmission device by the upper communication control device is used. In a wireless communication system that performs modulation processing and transmission, a receiving apparatus has a plurality of reception systems, and includes user orthogonalization means that performs user orthogonalization in the previous stage of frequency domain equalization, thereby causing unspecified number of interferences. The source is limited to signals (Co-channel interference) and desired signals originating from different transmitters with the same user identifier, and the respective transfer functions of Co-channel interference and desired signals are obtained, and different from the total received signals. Considering the user signal to be subtracted, means for obtaining the optimum demodulation coefficient for the desired signal, frequency domain conversion means for converting the total received signal to the frequency domain, and the demodulation target The optimal coefficient to the received signal, and a frequency domain compensation means for applying at least one complex multiplier, and executes the multi-path interference removal of the desired signal and Co-channel interference cancellation simultaneously.

  As a result, according to this receiver configuration, when performing multipath equalization of a user to be decoded in frequency domain equalization having a complex multiplier (only one in the optimal configuration), Co-channel interference Mitigation is performed simultaneously.

  In addition, the equalization / interference cancellation method of the present invention includes a measurement unit that obtains transfer signals of signals received by the same user identifier, that is, co-channel interference and a desired signal, and further, is unique to the receiver. A means to measure thermal noise is also provided.For example, after receiving with MMSE (Minimum Mean Square Error) coefficient considering multiple receiving systems for Co-channel interference, it is subtracted from the total received signal delayed, and then the desired signal It is characterized in that a frequency domain equalization coefficient equivalent to that received by the MMSE coefficient for the signal is obtained, and multi-path equalization for the desired signal can be performed simultaneously.

  As a result, according to this equalization / interference elimination method, a method that takes time to determine the coefficients based on learning represented by RLS (Recursive Least mean Square) and LMS (Least Mean Square) Unlike this, it is characterized in that an optimum coefficient is obtained immediately, and co-channel interference cancellation and multipath interference cancellation of a desired signal are performed simultaneously.

Furthermore, the transmission apparatus of the present invention is devised so that the transfer function of the transmission path can be obtained on the receiver side even in different cells and sectors.
As a result, according to this communication apparatus, in general, in order to improve the communication quality, the scramble method or the scramble coefficient differs between cells and sectors, and signals of other cells and sectors cannot be received. It is possible to obtain a transfer function of a -channel interference user, and to simultaneously perform co-channel interference cancellation and multipath interference cancellation of a desired signal.

In addition, the equalization / interference removal method of the present invention can also include the concept of multi-stage processing of the prior art, and in multi-stage processing, by performing interference removal from a signal having a large received power, It is devised to improve the interference removal performance.
As a result, this receiving apparatus is characterized in that the interference removal performance can be further improved.

The equivalent circuit schematic and block diagram which show embodiment of the receiver applied to the base station apparatus in the radio | wireless communications system by this invention. The conceptual diagram and block diagram of the equivalent circuit of interference removal and multipath equalization. The equivalent circuit schematic and block diagram which show other embodiment of the receiver applied to the base station apparatus in the radio | wireless communications system by this invention. The error characteristic figure which showed the effect in the case of 2 receiving systems in the receiver of this Embodiment shown in FIG.1 and FIG.3. The error characteristic figure which showed the effect in the case of 4 receiving systems in the receiver of this Embodiment shown in FIG.1 and FIG.3. The block diagram which shows an example of the transmitter of the radio | wireless communication terminal in the radio | wireless communications system by this invention. Explanatory drawing which shows the extraction method of the impulse response of the transmission line in the transmitter shown in FIG. The example of operation | movement of the radio | wireless communications system by the CIBS-CDMA system in a prior art. The block diagram of the radio | wireless communications system of a MUI free access system with which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Communication control apparatus 14 ... Base station apparatus 20 ... Wireless communication terminal
0101, 0105 ... User orthogonalization processing unit
0102, 0106, 0210 ... Time / frequency converter
0103, 0107, 0111, 0114, 0403, 0406, 0407, 0410 ... Adder (subtracter)
0109, 0110, 0104, 0108, 0112, 0113, 0211, 0401, 0402, 0404, 0405, 0408, 0409, 0411, 0412 ... complex multiplier
0115, 0212 ... Frequency / time converter
0201 ... Transmission data generator
0202, 0208 ... Multiplier
0203 ・ ・ ・ Interleaver
0204 ・ ・ ・ Guard interval giving part
0205 ・ ・ ・ Transmission / reception radio section
0206 ・ ・ ・ Guard interval remover
0207 ・ ・ ・ Deinterleaver
0209 ... Integrator
1001 ・ ・ ・ Pilot signal generator
1002 ... Identifier assigning section
1003 ・ ・ ・ Changeover switch

Claims (7)

A plurality of communication cells each including a plurality of wireless communication terminals and a base station device that accommodates each wireless communication terminal are arranged, and the communication control device controls a communication state in each communication cell, so that each communication cell Each of the wireless communication terminals within the communication station modulates and transmits a transmission signal using a unique orthogonal identifier assigned by the communication control device, and transmits a plurality of the transmission signals to the base station in the same communication cell. In a wireless communication method received by a device,
The base station device in each of the communication cells is
When receiving an output from the wireless communication terminal having a plurality of reception systems and having the same orthogonal identifier in another communication cell different from the communication cell, the result is a combination of the plurality of reception systems. A first process of creating an interference signal for removal using the interference signal and removing the interference signal from the received signal in each of the reception systems;
A wireless communication method characterized in that the second processing for performing transmission path fluctuation equalization on the received signal of each receiving system can be executed by circuit processing having the same configuration in the frequency domain. Each wireless communication terminal in each communication cell is configured to transmit and output including a cell identifier unique to the communication cell,
The base station device in each of the communication cells is
2. The radio according to claim 1, wherein a transfer function of only the cancellation interference signal is obtained based on the cell identifier included in the received output of the radio communication terminal, and the first process is executed. Communication method. A plurality of communication cells each including a plurality of wireless communication terminals and a base station device that accommodates each wireless communication terminal are arranged, and the communication control device controls a communication state in each communication cell, so that each communication cell Each of the wireless communication terminals within the communication station modulates and transmits a transmission signal using a unique orthogonal identifier assigned by the communication control device, and transmits a plurality of the transmission signals to the base station in the same communication cell. In the base station device in each communication cell in the wireless communication method received by the device,
An orthogonalization processing unit that has a plurality of reception systems and removes reception signals of orthogonal identifiers having different orthogonal identifiers in another communication cell different from the communication cell;
A frequency conversion unit for converting the output from the orthogonalization processing unit into a frequency domain;
Create an interference signal for removal using an interference signal generated as a result of combining all the reception systems with the output from the frequency converter, and after removing each interference signal from the reception signal in each reception system, A base station apparatus comprising: a frequency domain compensator that performs transmission path fluctuation equalization on a received signal. The frequency domain compensator is
The base station apparatus according to claim 3, wherein the base station apparatus is a single complex multiplier that performs the interference cancellation and the transmission path fluctuation equalization by linear processing in the frequency domain. After provisionally receiving in the frequency domain compensation unit using the MMSE (Minimum Mean Square Error) coefficient obtained from the transfer function of all receiving systems for the interference signal arriving from a communication cell different from the communication cell, Each transfer function of the interference signal in the reception system is given and subtracted from the reception signal of each reception system, and then received with the MMSE coefficient for the demodulated user using the transfer function of the user to be demodulated. The base station apparatus according to claim 3. The base station apparatus according to claim 3, wherein the processing order of the orthogonal processing unit and the frequency conversion unit is switched. The frequency domain compensator is
Determining whether or not an interference signal is generated as a result of combining in the plurality of receiving systems, based on a cell identifier unique to the communication cell included in a transmission output from each wireless communication terminal in each communication cell. The base station apparatus according to claim 3, wherein:

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