JP2012178849A - Mobile terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of realizing improvement of communication quality between a mobile terminal and a base station.SOLUTION: A mobile terminal comprises: a reception processing part which receives a signal; and a transmission processing part which determines multiple subcarriers based on the received signal so that a ratio of allocating subcarriers to fading generation subcarriers is uniform between branches and notifies a transmission source of the received signal of the determined multiple subcarriers.

Description

The present invention relates to OFCDM (Orthogonal Frequency and Code Division Multiplexing) and O
The present invention relates to a technique suitably applied to a mobile communication system that performs data transmission using multicarriers such as FDM (Orthogonal Frequency Division Multiplexing).

The OFCDM system is a system that further performs code division multiplexing using spreading codes in an OFDM (Orthogonal Frequency Division Multiplexing) system that transmits data in parallel using a plurality of subcarriers. Thereby, user multiplexing at the same frequency can be achieved.

The OFDM system has the following advantages.
(1) Strong against narrowband interference
(2) Strong against frequency selective fading
(3) High frequency utilization efficiency (because frequency sharing between subcarriers is possible)
(4) Frequency domain processing is possible The outline of the OFCDM transmission method is as follows (see, for example, Patent Document 1).
<1> First, an information symbol to be transmitted is prepared.
<2> Error correction coding such as turbo coding is performed on the information symbols.
<3> Predetermined data modulation processing (for example, QPS) is performed on the error correction encoded information symbol.
K modulation) is performed.
<4> The modulated information symbol is serial-parallel converted.
<5> Information symbols subjected to serial-parallel conversion are duplicated by a number equal to the spreading period (spreading factor) of the spreading code according to a predetermined spreading factor (SF).
<6> Each duplicated information symbol is multiplied by one chip of the spreading code.
<7> Information symbols multiplied by spreading codes are multiplexed.
<8> Frequency / time conversion (IFFT: inverse fast Fourier transform) processing is performed on the multiplexed information symbols. By this, OFCDM transmission signal (orthogonal multicarrier signal)
Is generated.
<9> A guard interval (GI) is inserted for each information symbol of the OFCDM transmission signal.
<10> An OFCDM transmission signal including spread parallel symbols is transmitted by wireless communication using carriers (multicarriers) of various frequencies.

In OFCDM, transmission using a plurality of subcarriers is performed as shown in FIG. For this reason, even if frequency selective fading occurs, only a certain subcarrier needs to be affected by fading. Furthermore, for affected subcarriers, this effect can be regarded as flat fading (simple attenuation). In this case, the SIR (Signal to Interference Ratio) of the subcarrier is lower than the target value. Therefore, in transmission power control for each subcarrier (subcarrier transmission power control method: Sub Carrier Transmit Power Control (STPC)), if the transmission power of the subcarrier is increased, this problem due to frequency selective fading can be avoided. Can do.

On the other hand, in the case of a single carrier such as CDMA (Code Division Multiple Access), when frequency selective fading occurs, the entire transmission carrier is affected. This affects the entire transmission data. This effect has been difficult to improve by transmission power control (TPC). That is, with a single carrier, it is difficult to improve the bit error rate by improving the influence of frequency selective fading.

  As described above, in a system that performs radio transmission using subcarriers such as OFCDM, the use of STPC can suppress the influence of frequency selective fading compared to radio transmission using a single carrier. .

  However, STPC can affect other calls. That is, as shown in FIG. 23, when a reception power level falls due to the influence of frequency selective fading in a certain mobile station (Mobile Station (MS): mobile terminal) # 0, the mobile station # 0 Request transmission power increase. As a result, the mobile device # 0 can secure a desired SIR. However, such an increase in transmission power may lead to an increase in the noise component in the corresponding subcarrier received by the other mobile device # 1.

  In order to solve such a problem, a method of not using a subcarrier in which a drop in reception level has been proposed (for example, see Non-Patent Document 1).

  In view of the problem that transmission efficiency decreases when not used simply, a PNPA (Partial Non-Power Allocation) method that assigns punctured bits to unused subcarriers has been proposed (for example, non-power allocation). Patent Document 2).

By the way, in the DHO (Diversity Hand Over) method in which the mobile device is in communication with a plurality of base stations in the 3GPP method, the same data is transmitted on all transmission paths (branches) by a single carrier. On the receiving side, the data from each branch is combined to reproduce the data. In this case, if affected by frequency selective fading in each branch, no matter how the data received from each branch was selected during synthesis on the receiving side, it was affected by frequency selective fading. There was a problem of becoming something.

  In addition, when soft handover is performed, the same data flows on a plurality of transmission paths. This implies that the line usage efficiency for ensuring a certain quality is poor. For example, when an RNC (Radio Network Controller: base station controller) has a function unit for performing data selection / combination, each Iub (RNC-) is used in both the uplink and the downlink. The same data flows on the interface between Node B (base station).

  Furthermore, with respect to uplink transmission, 3GPP has a specification in which a mobile device transmits the same data to all base stations.

JP 2004-134978 A

Toshimitsu Tsuji, Yoichi Matsumoto, Masahiro Umehira, "A Study on ARQ for Wireless ATM Using OFDM Subcarrier Information", IEICE 1997 Communication Society Conference Proceedings 1, IEICE, 1997 8 Issued on May 13, p332 Noriyuki Maeda, Seiichi Sampei, Norihiko Morinaga, “Characteristics of subcarrier transmission power control scheme using delay profile information channel in OFDM / FDD system”, IEICE Transactions Vol.J84-B No.2, Incorporated Association The Institute of Electronics, Information and Communication Engineers, issued February 1, 2001, No. 398, p205-207

  The present invention has been made in view of the above-described problems. That is, an object of the present invention is to provide a technique capable of improving quality in communication between a mobile terminal and a base station.

  Moreover, the objective of this invention is providing the technique which can perform efficient communication between a mobile terminal and a base station.

The present invention adopts the following configuration in order to solve the above problems. That is, the present invention is a mobile terminal,
A data generation unit for generating first data and second data;
A radio transmission unit that performs radio transmission according to an OFDM scheme using the first subcarrier group for the first data and the second subcarrier group for the second data.

  In the mobile terminal according to the present invention, it is preferable that the first data and the second data are part of data subjected to error correction coding.

  Also, the mobile terminal according to the present invention transmits information for identifying subcarriers included in the first subcarrier group and subcarriers included in the second subcarrier group among a plurality of subcarriers. It is preferable to further include a transmission unit.

  In the mobile terminal according to the present invention, the first subcarrier group and the second subcarrier group are subcarriers obtained by dividing a subcarrier candidate group including a plurality of subcarriers based on a radio environment. A group is preferred.

A mobile terminal according to the present invention includes a radio environment for a plurality of subcarriers between a first antenna provided in a base station and a mobile station, and a plurality of sub-carriers provided between the second antenna provided in the base station and the mobile station. A radio environment measurement unit for measuring the radio environment of the subcarrier;
A subcarrier setting unit configured to set the first subcarrier group and the second subcarrier group based on the measurement result;
Data transmitted using the first subcarrier group is subjected to reception processing by a receiving unit including the first antenna, and data transmitted using the second subcarrier group includes the second antenna. It is preferable that reception processing is performed by the receiving unit.

The present invention also provides a reception processing unit that receives the different signals from the first and second antennas in a situation where different signals are transmitted according to the OFDM scheme,
For a base station that transmits a signal from the first antenna to the mobile station, a subcarrier group that the base station uses for transmission to the mobile station is designated based on a received signal from the base station A transmission processing unit for transmitting information to be transmitted,
It is a mobile terminal provided with.

Further, the present invention is a wireless communication apparatus that transmits and receives a multicarrier signal using a plurality of subcarriers,
An acquisition means for acquiring a wireless environment in each wireless transmission path when there are a plurality of wireless transmission paths for transmitting and receiving a multicarrier signal;
Assignment means for allocating subcarriers used for transmission and / or reception of multicarrier signals to each wireless transmission path based on the wireless environment obtained by the obtaining means.

The present invention also provides a second antenna different from the first antenna that transmits the first data to the mobile station using the first subcarrier group,
A transmission processing unit for transmitting second data to the mobile station using the second subcarrier group from the second antenna;
Is a base station apparatus.

  In the base station apparatus according to the present invention, it is preferable that the first antenna is provided in the base station apparatus or in another base station apparatus.

  In the base station apparatus according to the present invention, it is preferable that the transmission processing unit transmits reception quality information of a received signal from the base station received by the second antenna to the mobile station.

  ADVANTAGE OF THE INVENTION According to this invention, the improvement in the quality in communication between a mobile terminal and a base station can be aimed at.

  Further, according to the present invention, efficient communication can be performed between the mobile terminal and the base station.

FIG. 1 is a schematic explanatory diagram of the present invention, and is a table showing an example of subcarrier allocation states for each branch when there are 16 subcarriers and two branches. FIG. 2 is a table showing an example of determining whether or not frequency selective fading has occurred. FIG. 3 is a diagram illustrating an example of a basic frame format for sending feedback information. FIG. 4 is a diagram schematically showing a multicarrier signal in which a data area and a feedback information area are defined. FIG. 5 is a diagram illustrating an example of a feedback loop using an uplink and a downlink. FIG. 6 is a diagram illustrating a relationship between data during uplink transmission and downlink feedback information. FIG. 7 is a diagram illustrating a relationship between data during uplink transmission (when downlink subcarrier designation transmission is not performed) and uplink feedback information. FIG. 8 is a diagram illustrating a relationship between data during uplink transmission (when downlink subcarrier designation transmission is performed) and uplink feedback information. FIG. 9 is a diagram illustrating a configuration example of uplink feedback information. FIG. 10 is a diagram illustrating a configuration example of downlink feedback information. FIG. 11 is a table showing an example of subcarrier allocation based on the fading occurrence status. FIG. 12 is a table showing an example of subcarrier allocation based on the fading occurrence status. FIG. 13 is a diagram illustrating the relationship between SF and subcarriers. FIG. 14 is a table showing an example of subcarrier allocation in the case of SF = 4. FIG. 15 is a diagram illustrating a configuration example of a mobile device and a base station (node B) in the embodiment. FIG. 16 is a diagram illustrating an example of the mobile communication system in the application example. FIG. 17 is a diagram illustrating a configuration example of the DHO processing unit. FIG. 18 is a diagram illustrating a configuration example for realizing the data division ratio determination process. FIG. 19 is a diagram illustrating a configuration example of a base station and a mobile device in an application example. FIG. 20 is an explanatory diagram illustrating an example of uplink transmission in the application example. FIG. 21 is an explanatory diagram illustrating an example of downlink transmission in the application example. It is a figure which shows the difference of the influence of frequency selective fading with respect to a single carrier signal and an orthogonal multicarrier signal. It is a figure which shows the influence on the subcarrier for other mobile devices by the increase in the transmission power of the subcarrier for a certain mobile device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The configuration of the embodiment is an exemplification, and the present invention is not limited to the configuration of the embodiment.

<Outline of the present invention>
The present invention determines whether or not subcarriers can be used in units of subcarriers in a multicarrier communication system such as an OFDM system (for example, OFCDM system). This possibility determination is based on, for example, the occurrence of frequency selective fading for each subcarrier using the transmission power level on the transmission side of the multicarrier signal and / or the reception level of the signal on the reception side of the multicarrier signal. Done.

Furthermore, the present invention is applicable to a case where a plurality of branches (wireless transmission paths) are connected between the transmission side and the reception side of a multicarrier signal, for example, when executing DHO (Diversity Hand Over). Subcarriers to be used in each branch are allocated. This allocation of subcarriers is performed based on the occurrence of frequency selective fading, for example. At this time, the correspondence between the branch and the base station may be one-to-one, or may be n-to-one (n is a natural number of 2 or more). That is, there may be one base station for one branch, and there may be one base station for a plurality of branches.

  FIG. 1 is a table showing an example of an assignment state of subcarriers to each branch when there are 17 subcarriers and two branches as an example.

  In FIG. 1, subcarriers indicated by crosses (×) are subcarriers that are determined to be unusable in the branch due to the influence of frequency selective fading.

  On the other hand, subcarriers indicated by circles (◯) are subcarriers assigned as transmission subcarriers in that branch based on the result of the availability determination.

In FIG. 1, subcarriers 0 to 3 are assigned to branch # 0, and subcarriers 4 to 16 are assigned to branch # 1. As a result, the transmission side and the reception side can transmit and receive data (radio signals) without the influence of frequency selective fading using the branches # 0 and # 1.

The present invention includes, for example, “communication system, transmission method” (international application number PCT / JP2005 / 04133, international application date March 9, 2005: international publication number WO 2006/095423: This patent application is referred to as “prior application”, and the invention according to this prior application is referred to as “prior application invention”). In this communication method, when there are a plurality of base stations (branches), the same data is not transmitted to each base station (branch), and the data is divided according to the number of branches (for example, the number of branches is N If it is a book, it is divided into N), and each base station transmits divided data (segments) through each branch. According to this communication method, the amount of data transmitted in one branch can be reduced, and the degree of noise in another branch can be reduced with respect to a certain branch.

  In application to such a communication system, the divided data can be transmitted using the subcarriers assigned to each branch described above. Further, data to be transmitted can be divided into PDU (Packet Data Unit) units in RLC (Radio Link Control) defined by 3GPP or logical channel (Logical CH) units and allocated to each branch.

<Subcarrier allocation>
Next, an embodiment of a method for assigning subcarriers to branches according to the present invention will be described.

<Fading occurrence judgment method>
In the present embodiment, the following method can be applied as a method for determining the occurrence of frequency selective fading for subcarriers.

(First method: estimation based on transmission power control information)
When communication is performed between a transmission side and a reception side using a wireless transmission path, transmission power control (T
PC) is performed. This TPC can be performed for each subcarrier in the multicarrier communication system (STPC).

  TPC will be briefly described. The reception side measures the SIR of the signal received from the transmission side through the wireless transmission path, and determines whether the measured SIR is lower or higher than the SIR target value. At this time, if the SIR is lower than the target value, TPC information instructing an increase (Up) of the transmission power on the transmission side is generated. If the SIR is higher than the target value, the transmission power of the transmission side is generated. TPC information for instructing reduction is generated. The TPC information is sent to the transmission side. The transmission side controls (increases / decreases) the transmission power of the signal to the reception side according to the instruction by the TPC information.

  The transmission side of the multicarrier transmission signal (OFCDM transmission signal) can detect the reception power fluctuation of each subcarrier through such TPC information. That is, it is possible to determine whether or not a subcarrier that is a power control target is affected by frequency selective fading from the amount of power increase during a certain period.

  FIG. 2 is a table showing an example of determining whether or not frequency selective fading has occurred. In FIG. 2, each time TPC information is received, the transmission side accumulates the instruction content by the TPC information in the storage device a predetermined number of times (in the example of FIG. 2, 10 times). When the instruction content is accumulated a predetermined number of times, it is determined whether or not the accumulated content satisfies the determination condition indicated by the determination information on whether or not fading has been stored in the storage device in advance.

  In the example shown in FIG. 2, the determination condition for determining that fading has occurred if the increase instruction is 8 times or more in the TPC information for 10 times is shown. Here, 8 out of 10 instructions are increase instructions, so the transmitting side determines that this subcarrier is affected by fading (fading has occurred).

  Such a first method can also be implemented on the receiving side by accumulating TPC information to be sent to the transmitting side.

(Second method: reception level determination on the receiving side)
The receiving side of the multicarrier signal calculates an average reception level for a plurality of subcarriers of the multicarrier signal in a predetermined measurement period, and compares this average reception level with the reception level of the subcarrier to be determined, Whether or not fading has occurred can be determined. The calculation of the average reception level may include or exclude the reception level of the determination target subcarrier.

  Specifically, the reception side measures the reception levels of a plurality of subcarriers in a predetermined measurement period or timing, and calculates the average reception level in the measurement period. Next, the reception side extracts the reception level of the measurement target subcarrier and calculates the difference between the reception level and the average reception level (reception level difference = average reception level−determination target reception level).

Next, the reception side reads fading presence / absence determination data (eg, a reference value of the reception level) stored in advance in the storage device and compares it with the difference. At this time, if the difference is larger than the reference value (reception level difference> reference value), the receiving side determines that fading has occurred. On the other hand, when the difference is equal to or smaller than the reference value (reception level difference ≦ reference value), it is determined that fading has not occurred.

(Third method: combination of the first method and the second method)
The first method and the second method described above can be combined to form a third method. That is, the determination result obtained by the first method (fading information (for example, 0 (occurrence) / 1 (not generated))) and the determination result obtained by the second method (fading information (for example, 0 (occurrence)) / 1 (not generated))), the presence or absence of fading can be determined.

  For example, the logical product or logical sum of the fading information obtained by the first and second methods is calculated, and it is determined that fading has occurred when the result is “1”.

《Feedback information》
The determination results (fading information) by the first to third methods described above can be sent to the other party as feedback information when the subcarrier is assigned based on the fading information on the other party.

  As described above, the first method can be executed on one of the transmission side and the reception side of the multicarrier signal. When the first method is executed on the transmission side, the fading information obtained by the first method can be sent to the reception side as feedback information. On the other hand, when the first method is executed on the receiving side, the fading information obtained by the first method can be sent to the transmitting side as feedback information.

  The second method is performed on the receiving side of the multicarrier signal. The fading information obtained by the second method can be sent to the transmission side as feedback information.

  The third method is performed on one of the transmission side and the reception side of the multicarrier signal. When the third method is executed on the receiving side, the receiving side uses the determination result of the third method obtained from the determination results of the first and second methods executed on the receiving side as feedback information. Can be sent to the sender.

  On the other hand, when the third method is executed on the transmission side, the transmission side performs fading information based on the first method executed on the transmission side and fading information based on the second method executed on the reception side ( The third method based on (feedback information) can be executed, and the result can be sent to the receiving side as feedback information.

  Note that the measurement result of the reception power level fluctuation in the first method, the measurement of the reception level and the calculation result of the average reception level in the second method are sent as feedback information to the partner side, and the information sent on the partner side The process for determining the occurrence of fading based on the above may be executed.

  Note that any known method can be applied to determine the occurrence of frequency selective fading for subcarriers.

《Feedback method》
As described above, the fading information for each subcarrier obtained on one side of the transmission side and the reception side can be sent to the other side as feedback information.

  The feedback information can be sent to the other party together with the data to be transmitted, for example. FIG. 3 shows an example of a basic frame format for sending feedback information.

As shown in FIG. 3, the frame includes a data area (Data Subframe) for storing data,
A feedback information area (Feedback Information Subframe) for storing feedback information is defined.

FIG. 4 is a diagram schematically showing a multicarrier signal (for example, OFCDM signal) in which a data area and a feedback information area are defined. FIG. 4 shows a case where the number of subcarriers is 16.

In the example shown in FIG. 4, a feedback information area is defined for the first two rows (2 blocks) in all subcarriers, and a data area is defined behind the feedback information area. However, the position of the feedback information area in each subcarrier may be arbitrary. That is, the position of the feedback information area may be different between subcarriers. Further, the ratio occupied by the feedback information area in each subcarrier (the number of blocks used in the feedback information area in FIG. 4) is also arbitrary.

  The feedback information region is preferably defined over all subcarriers used in the multicarrier signal. Even when a certain subcarrier is not used for data transmission by subcarrier allocation, if the feedback information is allocated to the subcarrier, the reception level of the subcarrier can be measured on the receiving side. Because it becomes.

  Therefore, feedback information does not necessarily have to be assigned to subcarriers that are not used. For example, in FIG. 4, when subcarriers # 0 to # 7 are not used, feedback information related to subcarriers # 0 to # 7 may be assigned to subcarriers # 8 to 15. In this case, dummy data for reception level measurement can be assigned to subcarriers # 0 to # 7.

  Note that the data area includes TPC information (TPC bits) for each subcarrier transmitted from the receiving side of the radio signal to the transmitting side.

《Feedback loop》
FIG. 5 is a diagram illustrating an example of a feedback loop using an uplink and a downlink. In the example shown in FIG. 5, a mobile device (UE: mobile terminal) has a plurality of Node Bs (base stations: # 0 and # 1) and an uplink (mobile device) via Uu (mobile device-base station interface). Unit → base station) and downlink (base station → mobile station).

  Further, FIG. 5 shows an example in which the second method is executed by the mobile device for the uplink and the second method is executed by the mobile device for the downlink as the fading occurrence determination method.

  In the example shown in FIG. 5, for the uplink communication, the mobile station sets a plurality of subcarriers used in multicarrier signal transmission to a number corresponding to the transmission path (branches: here, base stations # 0 and # 1). It can be divided into a plurality of subcarrier groups, and each subcarrier group can be assigned to each branch. That is, the mobile device can determine subcarriers used in each of a plurality of branches used in uplink communication.

Further, in the example shown in FIG. 5, when the mobile station uses different subcarriers (subcarrier groups) in downlink communication, a plurality of branches (base stations # 0 and # 1) use different subcarriers (subcarrier groups).
A subcarrier (subcarrier group) used by each branch can be determined. In this way, downlink communication in which a plurality of branches use different subcarriers is referred to herein as “downlink subcarrier designation transmission”.

  In FIG. 5, each of the base stations # 0 and # 1 generates feedback information (uplink feedback information) to be transmitted to the mobile device through the downlink (ST1, ST2).

  The uplink feedback information is used for the mobile station to transmit data to each of the base stations # 0 and # 1 using the uplink. The uplink feedback information includes data division related information (also referred to as “subcarrier division information”) and uplink fading information.

  The data division related information includes designation of a subcarrier number (a subcarrier that the mobile station should receive from each base station) used when each of the base stations # 0 and # 1 performs downlink subcarrier designation transmission. The subcarrier division information is included only when subcarriers to be used by the base stations # 0 and # 1 are determined by the mobile station in order to execute downlink subcarrier designation transmission.

  The uplink fading information indicates a frequency selective fading occurrence determination result (fading information) for each subcarrier executed by the base stations # 0 and # 1.

  Uplink feedback information from each of the base stations # 0 and # 1 is received by the mobile device through the downlink of the interface Uu (ST3, ST4).

  The mobile device performs the following processing (ST5, ST6) based on the uplink feedback information from the base stations # 0 and # 1. In ST5, with respect to the base station # 0, the mobile station performs reception power level determination for each downlink subcarrier used by the base station # 0 and whether or not fading has occurred. Further, the mobile device recognizes the subcarrier number to be received from the base station # 0 through the downlink based on the designation of the subcarrier number included in the uplink feedback information from the base station # 0. This recognition is performed only in the case of downlink subcarrier designation transmission. Further, the mobile station acquires uplink fading information included in the uplink feedback information from the base station # 0.

  Also, in ST6, the mobile device performs the same process as the process (ST5) related to the uplink feedback information from the base station # 0 based on the uplink feedback information from the base station # 1.

  Next, the mobile station generates downlink feedback information to be transmitted to the base stations # 0 and # 1 through the uplink (ST7, ST8). Downlink feedback information is used for each base station # 0 and # 1 to transmit data to the mobile station through the downlink.

  The downlink feedback information includes data division related information (subcarrier division information). The subcarrier division information includes (1) designation information of subcarrier numbers to be received by the base stations # 0 and # 1 through the uplink, and (2) base stations # 0 and # 1 used for downlink transmission. Information (notification information) of the subcarrier number to be included.

As described above, the mobile device can determine the subcarrier (subcarrier group) that each base station (branch) uses for data transmission / reception in uplink / downlink communication. In the generation of downlink feedback information (ST7), the mobile station uses the subcarriers to be received by the base stations # 0 and # 1 through uplink communication based on the uplink fading information from the base stations # 0 and # 1. A number is determined and included in downlink feedback information as specified information.

  Further, when the mobile station determines to perform downlink subcarrier designation transmission based on the determination result of the occurrence of fading of subcarriers of the base stations # 0 and # 1, the base stations # 0 and # 1 Determines a subcarrier number to be used for downlink communication and includes it in the downlink feedback information as notification information.

  The downlink feedback information is transmitted to the base stations # 0 and # 1 through the uplink of the interface Uu (ST9, ST10).

  In the base station # 0, the following processing is executed based on the downlink feedback information (ST11). That is, base station # 0 recognizes a subcarrier number to be received in uplink communication based on the designation information. In addition, the base station # 0 performs reception power level measurement of a signal received through uplink communication and processing for determining whether or not fading has occurred. Base station # 1 also performs the same processing as base station # 0 based on downlink feedback information (ST12).

  Base stations # 0 and # 1 generate uplink feedback information based on the above processing (ST13, ST14). Then, uplink feedback information as described in ST1 and ST2 is generated. Such a feedback loop is formed between a plurality of base stations and mobile devices.

  The “transmission side” and “reception side” described in the above fading occurrence determination are focused on the uplink communication in the example shown in FIG. 5, and the mobile device corresponds to the “transmission side”. # 1 corresponds to the “receiving side”.

  6 to 8 are diagrams illustrating the relationship between data transmitted and received between the base stations # 0 and # 1 and the mobile device and feedback information in the feedback loop described above. In the examples shown in FIGS. 6 to 8, two branches # 0 and # 1 are assumed and 16 subcarriers are used.

  FIG. 6 is a diagram illustrating a relationship between data during uplink transmission and downlink feedback information. FIG. 6 shows a multicarrier signal (OFCDM signal) transmitted from a mobile device during uplink transmission.

  As shown in FIG. 6, the downlink feedback information is transmitted to the base stations (branches) # 0 and # 1 through the uplink together with the data. In FIG. 6, as an example, according to the determination and designation by the mobile device, the branch (base station) # 0 receives a portion corresponding to subcarriers # 0 to # 7 in this multicarrier signal, and subcarrier # 8 It is shown that branch (base station) # 1 receives a portion corresponding to ˜15.

  Note that the portion (area) received in each branch need not be divided into two as shown in FIG. That is, a discrete subcarrier number may be assigned to each branch. For example, subcarriers may be alternately assigned to branches # 0 and # 1.

  In FIG. 6, the data stored in the data area is considered as one data block, the portion received at branch # 0 is the first data block, and the portion received at branch # 1 is the second data block. Can be thought of as

FIG. 7 is a diagram illustrating a relationship between data during uplink transmission (when downlink subcarrier designation transmission is not performed) and uplink feedback information. FIG. 7 shows a multicarrier signal (OFCDM) transmitted to the mobile station through downlink branches # 0 and # 1.
Signal).

  When downlink subcarrier designation transmission is not executed, OFCDM signals using all subcarriers (# 0 to # 15) are transmitted for each branch # 0 and # 1. FIG. 7 shows an OFCDM signal of branch # 0 including data spread by spreading code # 0 and an OFCDM signal of branch # 1 including data spread by spreading code # 1. Each OFCDM signal includes downlink feedback information including fading information of subcarriers # 0 to # 15.

  FIG. 8 is a diagram illustrating a relationship between data during uplink transmission (when downlink subcarrier designation transmission is performed) and uplink feedback information.

  In FIG. 8, regarding downlink transmission, use of subcarriers # 0 to # 7 is determined for base station (branch) # 0, and use of subcarriers # 8 to 15 is determined for base station (branch) # 1. In this case, OFCDM signals transmitted from the base stations # 0 and # 1 are shown. Each OFCDM signal is in a state that does not include an unused subcarrier data area.

  As a result, the amount of data transmitted through each branch is reduced, and it is possible to efficiently use resources and prevent a signal from one branch from becoming a noise relative to a signal from another branch.

  7 and 8, the data included in the OFCDM signal may be the same data, or may be divided data (segments) when certain data is divided.

《Uplink feedback information》
FIG. 9 is a diagram illustrating a configuration example of uplink feedback information. Uplink feedback information is given to transmission target data at the time of downlink transmission.

  In the example shown in FIG. 9, as uplink feedback information, a bit map (fading information) indicating whether or not fading has occurred in each uplink subcarrier, and a bit map (subframe) indicating a reception target subcarrier of the mobile station (UE). In this example, the carrier division information is stored in the OFCDM signal.

  The fading information is information regarding the occurrence of fading for each subcarrier obtained by the above-described fading occurrence determination method (for example, the first or second method) regarding signal reception from the uplink in each base station. For example, it is composed of bits (0 (none) / 1 (present)) indicating whether or not fading has occurred for each subcarrier.

  On the other hand, the subcarrier division information indicates a subcarrier number notified to each base station from the mobile device as downlink feedback information, which the mobile device should receive (to be used by the base station). For example, the subcarrier division information is composed of a bit string corresponding to the number of subcarriers, the subcarrier number to be received is represented by “1”, and the subcarrier number that is not the reception target is represented by “0”.

  The fading information is indispensable information when fading occurrence determination is performed at the base station. However, when the first method is performed by the mobile device, the determination process at the base station (reception side) is not performed, so that there is no fading information in this case.

  On the other hand, the subcarrier division information is information notified from the mobile device to each base station, and has a strong meaning that the base station has received the designation from the mobile device. For this reason, the information is defined as an option.

《Downlink feedback information》
FIG. 10 is a diagram illustrating a configuration example of downlink feedback information. Downlink feedback information is given to transmission target data during uplink transmission.

In the example shown in FIG. 10, as downlink feedback information (subcarrier division information in downlink feedback information), a bitmap (uplink reception target subcarrier information) indicating uplink reception target subcarriers for each base station, and And a bitmap (downlink reception target subcarrier information) indicating reception target subcarriers from each base station of the mobile device (UE).

  The uplink reception target subcarrier information indicates a subcarrier number to be received by each base station. The downlink reception target subcarrier information indicates a subcarrier number to be received by the mobile station (that is, a subcarrier number to be transmitted by each base station).

  The uplink / downlink reception target subcarrier information is prepared for each base station (branch). Also, the uplink / downlink reception target subcarrier information is composed of, for example, a bit string corresponding to the total number of subcarriers, and the reception target subcarrier at the base station or mobile station is represented by “1”. Non-subcarriers are represented by “0”.

  The uplink reception target subcarrier information is included in the downlink feedback information as essential information. However, this information may be omitted when all subcarriers are to be received in each branch.

  On the other hand, downlink reception target subcarrier information is defined as an option included in downlink feedback information only when downlink subcarrier designation transmission is performed.

  Note that the target subcarrier number itself may be stored as information indicating the subcarrier number included as the subcarrier division information.

<Subcarrier assignment decision>
The mobile device determines subcarriers to be assigned to each of a plurality of branches (base stations) based on the determination process in the own device and the fading information obtained as feedback information.

  11 and 12 are tables showing examples of subcarrier allocation based on the fading occurrence status. The mobile station assigns each subcarrier to each branch so that the subcarrier in which fading occurs is not used in each branch.

  FIGS. 11 and 12 show an example in which 12 subcarriers are allocated to branches # 0 and # 1. In the example shown in FIG. 11, fading occurs in subcarriers # 2 and # 3 in branch # 0. In branch # 1, fading occurs in subcarrier # 8.

  For this reason, subcarriers # 6 to # 12 are allocated to branch # 0 and subcarriers # 1 to # 5 are allocated to branch # 0 so that the subcarriers in which fading has occurred in each branch # 0 and # 1 are not allocated. It is determined to be assigned to 1.

  If the table of FIG. 11 is a table corresponding to the uplink, branches (base stations) # 0 and # 1 can receive OFCDM signals that are not affected by fading from the mobile device. On the other hand, if the table of FIG. 11 is a table corresponding to the downlink, the mobile device can receive OFCDM signals that are not affected by fading from each branch (base station) # 0 and # 1.

Thus, in this embodiment, the subcarrier candidate group (subcarriers # 1 to # 12) including a plurality of subcarriers is divided into the first subcarrier group (# 6 to # 12) and the second subcarrier group. It can be divided into carrier groups (# 1 to # 5).

  As shown in FIG. 12, depending on the occurrence of fading, there may be a case where a subcarrier in which fading has occurred must be allocated.

In FIG. 12, fading occurs in subcarriers # 3 and # 11 in branch # 0, and fading occurs in subcarriers # 2, # 6, and # 11 in branch # 1. At this time, if all the subcarriers must be assigned to branches # 0 and # 1, the ratio of the number of subcarriers in which fading has occurred to the number of subcarriers assigned to the branch (subcarriers assigned to the branch) (Fading occurrence subcarriers / assigned subcarriers (Branch # 0) ≒ Fading occurrence subcarriers / assigned sub) Carriers (Branch # 1)).

  In the example shown in FIG. 12, subcarriers # 6 to # 12 are assigned to branch # 0, and subcarriers # 1 to # 5 are assigned to branch # 1. Note that if it is possible to avoid the use of subcarriers in which fading has occurred in all branches, it is also possible to assign subcarriers # 11 so that they are not used.

  By the way, when OFCDM is applied, frequency spreading of information symbols is performed according to SF (spreading factor). For this reason, it is conceivable that a group spread according to SF, not a subcarrier as described above, is defined as a minimum allocation unit to each branch.

  FIG. 13 is a diagram illustrating the relationship between SF and subcarriers. FIG. 13 shows the case of SF = 4. In this case, four subcarriers corresponding to SF (spread code chip number) form one group, and allocation is determined in units of groups.

FIG. 14 is a table showing an example of assignment in the case of SF = 4. In FIG. 14, according to SF, subcarriers # 1 to # 4 form group # 0, subcarriers # 5 to # 8 form group # 1, and subcarriers # 9 to # 12 form group # 2. is doing. The fading occurrence situation is the same as in FIG. Groups # 0 and # 1 are assigned to branch # 1, and group # 2 is assigned to branch # 0.

<Allocation change method>
The subcarrier allocation process to each branch described above is executed at the start of uplink / downlink communication, for example. Thereafter, the allocation status can be changed as necessary. In this case, one of (1) a method for changing the subcarrier allocation status to be appropriate in real-time processing and (2) a method for changing (reviewing) the subcarrier allocation status at a fixed period is applied. be able to.

<Configuration example of mobile station and base station>
Next, a configuration example of a mobile device and a base station as a wireless communication device for realizing the processes and functions described so far will be described. FIG. 15 is a diagram illustrating a configuration example of a mobile device and a base station (Node B). In FIG. 15, each of the base stations # 0 and # 1 is wirelessly transmitted through a plurality of base stations # 0 and # 1 and two branches # 0 and # 1 formed between the base stations # 0 and # 1. A mobile device (mobile terminal) that performs communication is shown.

(Mobile machine)
The mobile device includes a reception processing unit 11 as a radio reception unit, a reception data processing unit 12, a subcarrier measurement unit 13, a reception carrier determination unit 14, a feedback information processing unit 15, a feedback information generation unit 16, A transmission carrier determination unit 17 as a subcarrier setting unit and a control unit, a transmission data processing unit 18 as a data generation unit, a feedback information adding unit 19, and a transmission processing unit 20 as an information transmission unit are provided.

The reception processing unit 11 is connected to a plurality of antennas (here, the first and second antennas A1 and A2) provided in the mobile device. The first antenna A1 receives the downlink OFCDM signal transmitted from the base station # 0, and the second antenna A2 receives the downlink OFCDM signal transmitted from the base station # 1. However, there may be one receiving antenna.

The reception processing unit 11 performs reception processing of signals received by the antennas A1 and A2. As reception processing, the reception processing unit 11 performs demodulation processing of each OFCDM signal. The reception processing unit 11 performs, as demodulation processing of each OFCDM signal, guard interval (GI) removal, Fourier transform (FFT), multiplication of spreading codes, symbol synthesis, parallel-serial conversion, data demodulation (for example, QPS)
K demodulation).

At this time, the reception processing unit 11 sends the feedback information area data (downlink feedback information) in each OFCDM signal to the feedback information processing unit 15 (no error correction coding or interleaving is performed on the feedback information). Assuming the case).

On the other hand, if the downlink subcarrier designation communication is not currently performed at the stage where data demodulation is performed on data in the data area in each OFCDM signal, the reception processing unit 11 performs deinterleaving and error on each data. Corrected demodulation and one of the obtained data (
For example, the one having the better reception level is selected and sent to the reception data processing unit 12. At this time, it is also possible to send the received data processing unit 12 with the quality improved by combining the two data.

On the other hand, the reception processing unit 11 performs the data demodulated data if the downlink subcarrier designation communication is currently performed at the stage where the data demodulation is performed on the data in the data area in each OFCDM signal. Assembling processing, deinterleaving processing and error correction demodulation processing for the assembling data are performed, and finally obtained data is sent to the reception data processing unit 12.

  Further, the reception processing unit 11 sends the demodulated data and downlink feedback information to the subcarrier measurement unit 13 as reception level measurement data.

  The reception data processing unit 12 executes predetermined processing based on the data received from the reception processing unit 11.

  The subcarrier measurement unit 13 executes reception level determination processing (fading occurrence determination processing) for each subcarrier related to each of the base stations # 0 and # 1 using the measurement data. The determination result is sent to the reception carrier determination unit 14.

The reception carrier determination unit 14 specifies (recognizes) a subcarrier in which fading has occurred (fading occurrence status) based on the determination result relating to each base station received from the subcarrier measurement unit 13. Based on this identification (recognition) result, the reception carrier determination unit 14 determines the reception target subcarrier (downlink reception target subcarrier) of the mobile station to be allocated to each base station (branch) (subcarrier for each branch). Assignment). The determination (allocation) result is sent to the feedback information generation unit 16.

  Thus, the reception carrier determination unit 14 determines whether or not to perform downlink subcarrier designation transmission described in the explanation of the feedback loop (FIG. 5). For example, when fading does not occur in each branch, the reception carrier determination unit 14 can determine that all subcarriers are used in each branch. In this case, notification to the feedback information generation unit 16 is not performed.

  The reception carrier determination unit 14 notifies the reception processing unit 11 of the determination result of the reception target subcarrier. As a result, the reception processing unit 11 performs reception processing from the base stations # 0 and # 1 for the reception target subcarriers specified as the determination result.

Based on the fading information included in the downlink feedback information from the base stations # 0 and # 1 received from the reception processing unit 11, the feedback information processing unit 15 causes fading for each branch # 0 and # 1. Identify (recognize) existing subcarriers. At this time, if necessary, the feedback information processing unit 15 performs reception level determination processing for each subcarrier of the OFCDM signal from each base station, and combines this determination result with fading information to generate final fading. Determination processing (third method) can also be performed. The feedback information processing unit 15 notifies the transmission carrier determination unit 17 of the recognition result (may be fading information) or the determination result by the above-described processing. Further, the feedback information processing unit 15 recognizes the designation information of the uplink reception target subcarriers included in the uplink feedback information.

Based on the notification (fading occurrence status) from the feedback information processing unit 15, the transmission carrier determination unit 17 is a subcarrier (uplink reception target subcarrier) that each of the base stations # 0 and # 1 should receive by uplink communication. To decide. That is, the transmission carrier determination unit 17 assigns a subcarrier number to be received to each base station. The determination (allocation) result is notified to the feedback information generation unit 16 and the transmission data processing unit 18.

  Note that the transmission carrier determination unit 17 can also determine to use all subcarriers for all branches when determining that fading has not occurred in any branch based on the fading occurrence status.

  The feedback information generation unit 16 generates downlink feedback information to be notified to the base stations # 0 and # 1. The downlink feedback information includes subcarrier division information. The subcarrier division information is generated based on the downlink reception target subcarrier determination result from the reception carrier determination unit 14 and the uplink reception target subcarrier determination result from the transmission carrier determination unit 17. The feedback information generation unit 16 notifies the downlink feedback information to the feedback information addition unit 19.

  The transmission data processing unit 18 performs error correction coding (for example, turbo coding) and interleaving on the data to be transmitted to the base station generated in the mobile device, and then gives the data to the feedback information adding unit 19.

  The feedback information adding unit 19 adds downlink feedback information to the input data and inputs the data to the transmission processing unit 20.

  The transmission processing unit 20 performs the following processing using the input data and downlink feedback information as transmission targets. That is, the transmission processing unit 20 performs data modulation processing (for example, QPSK modulation) for each of data and downlink feedback information.

  Furthermore, the transmission processing unit 20 performs orthogonal parallel transformation, information symbol duplication according to SF (spreading factor), multiplication of spreading code for each duplication, inverse fast Fourier transform (IFFT), guard interval as modulation processing by the OFCDM method. (GI) Insert. As a result, an OFCDM signal including data and downlink feedback information is created. The OFCDM signal is transmitted from the antenna A3. At this time, the antenna A1 or A2 may function as the antenna A3.

  Note that the mobile station can generate an OFCDM signal for each base station when different subcarriers are used between branches for uplink transmission (subcarriers are divided). In this case, the transmission data processing unit 18 divides the transmission target data for each base station after performing error correction coding and interleaving on the transmission target data.

  At this time, the transmission data processing unit 18 calculates the ratio of subcarriers allocated to each base station (branch) based on the determination result notified from the transmission carrier determination unit 17. The transmission data processing unit 18 divides the transmission target data into the same number of divided data (segments: first and second data) as the base station (number of branches) according to the calculated ratio.

  In this case, the feedback information giving unit 19 gives downlink feedback information to each segment, and the transmission processing unit 20 performs the above-described modulation processing on each segment and the pair of downlink feedback information, An OFCDM signal for the base station is generated and transmitted to each base station. In this case, a different spreading code is used for each base station.

  Note that the transmission carrier determination unit 17 as the control unit assigns a certain subcarrier to the first antenna (antenna A4) side and the second antenna (antenna A6) side. The antenna side that transmits a control signal (TPC information) that does not require an increase is configured to have priority over the antenna side that transmits a control signal (TPC information) that requests an increase in transmission power as an assignment destination of the subcarrier. be able to.

(base station)
Base stations # 0 and # 1 have the same configuration. The base station # 0 will be described as an example. As illustrated in FIG. 15, the base station # 0 includes a reception processing unit 21, a reception data processing unit 22, a subcarrier measurement unit 23 as a radio environment measurement unit, a feedback information processing unit 24, and a feedback information generation unit. 25, a transmission data processing unit 26, a feedback information adding unit 27, and a transmission processing unit 28.

  The reception processing unit 21 is connected to the reception antenna A4. The receiving antenna A4 receives the radio signal of the OFCDM signal transmitted from the mobile station antenna A3 through the uplink branch # 0.

  The reception processing unit 21 has substantially the same configuration as the reception processing unit 11 of the mobile device. However, data assembly between base stations as performed in the reception processing unit 11 is not executed. The reception processing unit 21 performs demodulation processing similar to that of the reception processing unit 11, and obtains data and uplink feedback information from the OFCDM signal.

  However, when receiving the designation of the uplink reception target subcarrier from the mobile station, the reception processing unit 21 demodulates the data stored in the data area of the uplink reception target subcarrier in the OFCDM signal. Process.

  The reception processing unit 21 sends data to the reception data processing unit 22 and sends uplink feedback information to the feedback information processing unit 24. Further, the reception processing unit 21 sends data and feedback information to the subcarrier measurement unit 23 as reception level measurement data.

  The reception data processing unit 22 executes predetermined processing relating to data received from the reception processing unit 21.

The subcarrier measurement unit 23 uses the data and feedback information from the reception processing unit 21 to execute the fading occurrence determination method shown as the second method. The execution result (fading occurrence status of each subcarrier and determination result of fading occurrence) is sent to the feedback information generation unit 25.

The feedback information processing unit 24 refers to the designation of the uplink reception target subcarrier included in the uplink feedback information (the number of the subcarrier group to be received by the base station # 0: designation information), and the designated number Recognize that reception processing should be performed on the subcarriers. In accordance with this recognition, the feedback information processing unit 24 instructs the reception processing unit 21 to perform reception processing for only the designated subcarrier number. This instruction is given, for example, by notification of designation information.

  Also, the feedback information processing unit 24 performs downlink transmission using the designated subcarrier when the uplink feedback information includes the number of subcarriers targeted for downlink reception (notification information). recognize. The feedback information processing unit 24 notifies the downlink reception target subcarrier number to the feedback information generation unit 25 and the transmission data processing unit 26.

  The feedback information generation unit 25 includes uplink fading information as a determination result from the subcarrier measurement unit 23 and an uplink reception target subcarrier number (subcarrier division information) from the feedback information processing unit 24. Feedback information is generated and notified to the feedback information adding unit 27.

The transmission data processing unit 26 sends data to be transmitted to the mobile device (error correction coding and interleaving are performed) to the feedback information adding unit 27. The feedback information giving unit 27 gives uplink feedback information to the transmission target data and sends it to the transmission processing unit 28.

  The transmission processing unit 28 has substantially the same configuration as the transmission processing unit 20 of the mobile device. The transmission processing unit 28 generates an OFCDM signal including the data from the feedback information adding unit 27 and the uplink feedback information, and transmits the signal from the antenna A5 to the base station. The radio signal of the OFCDM signal is received by the antenna A1 through the downlink branch # 0.

  The base station # 1 receives the radio signal of the OFCDM signal transmitted from the antenna A3 of the mobile station and transmitted through the uplink branch # 1 via the antenna A6. Base station # 1 transmits a radio signal of the OFCDM signal from antenna A7 to the mobile device. This radio signal is received by mobile station antenna A2 through downlink branch # 1. Each of the antennas A4 and A5 and the antennas A6 and A7 can be configured by one antenna element.

  Instead of the above-described configuration, error correction coding or interleaving may be performed on feedback information in a mobile device or a base station.

<Application example>
Next, as an application example, an embodiment in which the present invention is applied to a 3GPP mobile communication system will be described.

"System configuration"
FIG. 16 is a diagram illustrating an example of the mobile communication system in the application example. FIG. 16 shows, as a mobile communication system, a base station controller (Radio Network Controller (RNC)) 50 in a radio access network, a base station controller 50 and an interface Iu.
a plurality of base stations (base station devices: Node B) 60 and 70 connected via b, and wireless mobile devices (User Equipment (UE)) connected to the base stations 60 and 70 via a radio interface Uu 80.

When DHO is performed on the mobile device 80, the mobile device 80 is a wireless transmission path (branch) provided between the base station 60 and the mobile device 80 and between the base station 70 and the mobile device 80. # 0, #
The communication with the base stations 60 and 70 becomes possible through 1).

  That is, at the time of DHO, data to be transmitted to the mobile device 80 is transmitted from the base station control device 50 to the base stations 60 and 70. Each base station 60 and 70 generates a radio signal including the data and transmits the radio signal from each of the transmission antennas 61 and 71 included in the base station.

  Each radio signal is received by the mobile device 80 through the downlink branches # 0 and # 1, and the mobile device 80 includes antennas 81 to 84, for example, a radio signal from the base station 60 (# 0). Is received by the antenna 81, and a radio signal from the base station 70 (# 1) is received by the antenna 82.

  On the other hand, the mobile device 80 transmits uplink radio signals (including data to be transmitted to the base station controller 50) from the antennas 83 and 84 to the base stations 60 and 70, respectively. The base station 60 receives a signal from the mobile device 80 via its own antenna 62, and the base station 70 receives a signal from the mobile device 80 via its own antenna 72. Each base station 60 and 70 extracts data from the received radio signal and sends it to the base station controller 50.

In normal 3GPP, during DHO, the same data is transmitted to each base station in both downlink and uplink. On the other hand, in this embodiment, the data transmitted to each base station 60 and 70 is divided according to the radio environment (radio transmission path quality) between each base station 60 and 70 and the mobile device 80. .

  FIG. 17 is a diagram illustrating a configuration example of a DHO execution unit (DHO processing unit) provided in the base station control device 50, and FIG. 18 realizes a data division ratio determination process executed by the base station control device 50. It is a figure which shows the structural example for doing. The configuration shown in FIGS. 17 and 18 is a configuration according to the prior invention.

  The DHO processing unit 90 shown in FIG. 17 is provided in the base station control device 50 in this application example. However, the DHO processing unit 90 may be provided in a base station, a host device (not shown) of the base station control device, or a mobile terminal.

The DHO processing unit 90 includes a coding / decoding unit (Coding / Decoding) 91, an interleave / de-interleave unit (Interleave / De-interleave) 92, and a segmentation / reassemble unit 93. Yes.

  Data to be transmitted to the mobile device 80 is subjected to error correction coding by the encoding / decoding unit 91 and interleaved by the interleaving / deinterleaving unit 92. The interleaved data is divided by the dividing / assembling unit 93 into a number corresponding to the number of base stations (branches). In this application example, the data is divided into two segments. The divided data (segment) is transmitted from the base station controller 50 to the base stations 60 and 70.

  Each base station 60 and 70 uses the segment received from the base station controller 50 as a transmission target to the mobile device 80, generates an OFCDM signal including this segment, and transmits the OFCDM signal to the mobile device 80.

  On the other hand, when the segments are received from the base stations 60 and 70, the DHO processing unit 90 assembles the segments by the division / assembly unit 93. The interleave / deinterleave unit 92 deinterleaves the assembled data, and the encoding / decoding unit 91 performs error correction decoding.

  FIG. 18 shows a configuration for the DHO processing unit 90 to determine a data division ratio when dividing data. In order to determine the data division ratio, the base station controller 50 receives a data receiver 51 that receives data to be transmitted from the host device to the mobile device 80, and the transmission target data based on the wireless transmission path quality information. The apparatus includes a data division rate determination unit 52 that determines a division rate, and a data division / transmission unit 53 that divides transmission target data according to the division rate and transmits the data to the base stations 60 and 70. The DHO processing unit 90 is included in the data division / transmission unit 53.

  Each of the base stations 60 and 70 transmits to the base station control device 50 the wireless transmission path quality information related to the wireless transmission path (branch) corresponding to the own station. The wireless transmission path quality information is given to the data division ratio determination unit 52.

  In this application example, the subcarrier number to be used by each base station at the time of downlink subcarrier designation transmission received by each base station from the mobile station is applied as the radio transmission path quality information.

The data division ratio determining unit 52 determines the occupancy rate (subcarrier usage rate) of the usage target subcarriers with respect to the total number of subcarriers from the radio channel quality information (numbers of the usage target subcarrier groups) from each base station. Calculate for each base station (branch). The data division rate determination unit 52 determines the data division rate based on the ratio of the usage rates.

  For example, when the ratio of subcarriers in the base station 60 (# 0) and the base station 70 (# 1) is 50%, the data division ratio determination unit 52 sets the data division ratio to 1: 1. decide. Note that the mounting position of the data division ratio determination unit can be changed according to the mounting position of the DHO processing unit 90.

FIG. 19 is a diagram illustrating a configuration example of the base stations 60 and 70 and the mobile device 80 in the application example. The base stations 60 and 70 and the mobile device 80 shown in FIG. 19 have substantially the same configuration as the mobile device and the base station shown in FIG. However, in the base stations 60 and 70, the transmission data processing unit 26 receives data transmitted from the base station control device 50.

  Further, the number of subcarriers (subcarrier group) to be used in the base station when executing downlink subcarrier designation transmission, which is output from the feedback information processing unit 24, is transmitted to the base station controller 50 as radio channel quality information. Sent.

  When downlink subcarrier designation transmission is not executed, the mobile station 80 obtains the fading occurrence rate in each branch from the fading occurrence state for each subcarrier, and reduces the fading occurrence rate instead of the downlink reception target subcarrier number. It may be included in the link feedback information. In this case, the fading occurrence rate of each branch is notified to the data division rate determination unit 52 of the base station controller 50. At this time, the data division rate determination unit 52 can determine the ratio of fading occurrence rates between branches as the data division rate. Instead of the fading occurrence rate, an effective subcarrier ratio may be obtained.

<Uplink transmission>
FIG. 20 is an explanatory diagram illustrating an example of uplink transmission in the application example. First, before the start of communication, the subcarrier group to be received by each base station 60 (# 0) and 70 (# 1) determines that the mobile station 80 and each base station 60 and 70 are based on the feedback information. Determined between. The determination result (the number of the uplink reception target subcarrier group of each base station) is notified from the base stations 60 and 70 to the base station controller 50 (DHO processing unit 90) as necessary. At this time, information for performing deinterleaving and error correction decoding in the base station controller 50 may be notified from the mobile device 80 to the base station controller 50.

In uplink transmission, the mobile device 80 performs error correction coding and interleaving processing of transmission target data on the data, and then all subcarriers (subcarriers # 0 to ## in FIG. 20).
15) is used to transmit data.

  Each base station 60 and 70 receives data transmitted from the mobile device 80, and in accordance with a predetermined reception valid carrier (uplink reception target subcarrier number), data carried by the target subcarrier. Only receive.

  Here, the reception target subcarriers of base station 60 (branch # 0) are subcarriers # 0 to # 7. On the other hand, the reception target subcarriers of the base station 70 (branch # 1) are subcarriers # 8 to # 15. Each base station 60 and 70 performs data reception processing on the target subcarrier. However, the feedback information is subjected to reception processing for all subcarriers. Each base station 60 and 70 reproduces the data received on the reception target subcarrier. As a result, a segment in which the data transmitted from the mobile device 80 is divided is generated. Each base station 60 and 70 sends each segment to a base station controller (RNC) 50.

The base station controller 50 (DHO processing unit 90) performs assembly processing, deinterleaving, and error correction decoding of segments received from the base stations 60 and 70. Thereby, the data transmitted from the mobile device 80 is reproduced.

《Downlink transmission》
FIG. 21 is an explanatory diagram illustrating an example of downlink transmission in the application example. FIG. 21 shows a case where downlink subcarrier designation transmission is executed.

  In downlink transmission, a subcarrier group to be transmitted in each base station 60 and 70 is determined between the mobile device 80 and each base station 60 and 70 based on feedback information before starting communication.

  The determined information (downlink reception target subcarrier number) is notified to the base station controller 50. In the base station control device 50, the data division ratio determination unit 52 determines the data division ratio. In the downlink transmission, the DHO processing unit 90 performs error correction encoding and interleaving processing of data to be transmitted to the mobile device 80, and then performs data segmentation (division) according to a predetermined data division ratio, Send the segment to the corresponding base station.

  Each base station 60 and 70 transmits the divided data (segment) received from the base station control device 50 using a predetermined transmission effective carrier (downlink transmission target subcarrier).

  In the example illustrated in FIG. 21, the downlink transmission target subcarrier groups for the base station 60 are subcarriers # 0 to # 7, and the downlink transmission target subcarrier groups for the base station 70 are subcarriers # 8 to # 15. is there. Base station 60 transmits segments using subcarriers # 0 to # 7, and base station 70 transmits segments using subcarriers # 8 to # 15.

  The mobile device 80 receives the divided data (segments) from the base stations 60 and 70. The mobile device 80 assembles a plurality of segments according to the error correction coding and interleaving contents notified in advance, and executes deinterleaving and error correction decoding processing. As a result, the data transmitted from the base station control device 50 is reproduced.

  At the time of downlink transmission, the spreading code used for downlink transmission differs for each base station. Therefore, as a data division transmission method, each base station may perform downlink transmission using all subcarriers instead of using a part of subcarriers as in the example shown in FIG. Yes (see FIG. 7).

  In this case, as described above, as the downlink feedback information, the Fading occurrence rate or the effective subcarrier ratio in each downlink branch is notified to the data division rate determination unit 52 as the data division rate determination material. Also good.

  In the application example, the downlink feedback information can be modified so as to include the identification information of the base station that performs the process of reproducing the data received from the mobile device 80.

Each base station (for example, a transmission processing unit) as a wireless communication device increases the number of subcarriers used for transmission of transmission target data (segments) as necessary (for example, from a natural number N to M). The subcarrier number changing unit (subcarrier control unit) that increases) and the spreading factor (SF) is changed according to the change in the number of subcarriers (the spreading factor is decreased (increased) when the subcarrier number increases (decreases). And a spreading factor control unit that performs control.

<Effects of Embodiment>
According to the embodiment described above, when there are a plurality of wireless transmission paths (branches) between the base station and the mobile station, the frequency for each subcarrier is related to uplink transmission and downlink transmission using these branches. A selectivity fading occurrence determination process is executed. Based on the determination result, a subcarrier (subcarrier group) to be received or transmitted is assigned to each branch (base station).

  Thereby, in each branch, subcarriers can be allocated such that fading-caused subcarriers are not used. As a result, high-quality uplink or downlink transmission / reception can be performed.

  Further, since a subcarrier in which fading has occurred is not used, it is not necessary to perform transmission power control for that subcarrier. For this reason, it can suppress that the noise in another subcarrier generate | occur | produces by the transmission power increase of a certain subcarrier.

  Furthermore, since the data is divided into a plurality of segments, the amount of data transmitted in each branch can be reduced, so that efficient communication and effective use of resources can be achieved.

  Further, subcarriers that are not used between a certain base station and a mobile device can be allocated between other base stations and the mobile device. As a result, effective use of radio resources can be achieved.

  In addition, in a mobile device, when data is divided into segments and each segment is transmitted to each branch, the amount of data transmitted through each branch can be suppressed, and communication efficiency and effective use of radio resources can be reduced. Can be planned.

<Others>
(Appendix 1)
A data generation unit for generating first data and second data;
A wireless transmission unit that wirelessly transmits according to an OFDM scheme using a first subcarrier group for the first data and a second subcarrier group for the second data;
Mobile terminal equipped with.
(Appendix 2)
The first data and the second data are part of error-corrected encoded data.
The mobile terminal according to attachment 1.
(Appendix 3)
The additional description 1 further provided with the information transmission part which transmits the information which identifies the subcarrier contained in the said 1st subcarrier group among the several subcarriers, and the subcarrier contained in the said 2nd subcarrier group. Mobile terminal.
(Appendix 4)
The mobile terminal according to supplementary note 3, wherein the information transmitting unit transmits using either one or both of the first subcarrier group and the second subcarrier group.
(Appendix 5)
The mobile terminal according to supplementary note 3, wherein the information includes information capable of identifying a base station that is to perform a reproduction process on each of the first data and the second data.
(Appendix 6)
The mobile terminal according to supplementary note 1, wherein the first and second subcarrier groups are subcarrier groups obtained by dividing a subcarrier candidate group including a plurality of subcarriers based on a radio environment.
(Appendix 7)
A radio environment for a plurality of subcarriers between the first antenna and the mobile station provided in the base station, and a radio environment for a plurality of subcarriers provided between the second antenna and the mobile station provided in the base station; A wireless environment measurement unit for measuring
A subcarrier setting unit configured to set the first subcarrier group and the second subcarrier group based on the measurement result;
Data transmitted using the first subcarrier group is subjected to reception processing by a receiving unit including the first antenna, and data transmitted using the second subcarrier group includes the second antenna. The mobile terminal according to appendix 1, wherein reception processing is performed by the receiving unit.
(Appendix 8)
A reception processing unit that receives the different signals in a situation where different signals are transmitted from the first and second antennas according to the OFDM scheme;
For a base station that transmits a signal from the first antenna to the mobile station, a subcarrier group that the base station uses for transmission to the mobile station is designated based on a received signal from the base station And a transmission processing unit that transmits information to be transmitted.
(Appendix 9)
The ODFM scheme is an OFCDM scheme using code division, and a minimum unit of information transmitted using the first and second subcarriers is equal to a chip length of a spreading code.
The mobile terminal according to attachment 1.
(Appendix 10)
The OFDM scheme is an OFCDM scheme using code division, and the subcarrier group includes a number of subcarriers equal to or greater than a spreading factor.
The mobile terminal according to attachment 1.
(Appendix 11)
2. The mobile terminal according to supplementary note 1, wherein the OFDM scheme is an OFCDM scheme using code division, and is configured by using a plurality of subcarrier groups each having a spreading code chip count as one group.
(Appendix 12)
A reception processing unit that receives a control signal for transmission power control for each subcarrier generated by reception quality evaluation according to each of the first and second antennas that receive the wirelessly transmitted signal;
When assigning a plurality of subcarriers to the first antenna side and the second antenna side, a control signal requesting an increase in transmission power is transmitted to an antenna side that transmits a control signal not requiring an increase in transmission power. A control unit that gives priority as a subcarrier allocation destination over the transmitting antenna side;
The mobile terminal according to appendix 1, further comprising:
(Appendix 13)
A wireless communication apparatus that transmits and receives a multicarrier signal using a plurality of subcarriers,
An acquisition means for acquiring a wireless environment in each wireless transmission path when there are a plurality of wireless transmission paths for transmitting and receiving a multicarrier signal;
A wireless communication apparatus comprising: assignment means for assigning subcarriers used for transmission and / or reception of multicarrier signals to each wireless transmission path based on the wireless environment obtained by the obtaining means.
(Appendix 14)
A second antenna different from the first antenna that transmits the first data to the mobile station using the first subcarrier group;
A transmission processing unit for transmitting second data to the mobile station using the second subcarrier group from the second antenna;
A base station apparatus.
(Appendix 15)
The first antenna is provided in the base station device or in another base station device,
The base station apparatus according to appendix 14.
(Appendix 16)
15. The base station apparatus according to supplementary note 14, wherein the first and second data are a part of data subjected to error correction coding.
(Appendix 17)
15. The base station apparatus according to supplementary note 14, further comprising a subcarrier selection unit that selects the second subcarrier group from a plurality of subcarriers based on information from the mobile station.
(Appendix 18)
The base station apparatus according to appendix 17, wherein the information is generated according to a radio environment between the second antenna and the mobile station.
(Appendix 19)
The base station apparatus according to supplementary note 14, wherein the transmission processing unit transmits reception quality information of a received signal from the base station received by the second antenna to the mobile station.
(Appendix 20)
In a radio communication apparatus capable of radio transmission according to an OFDM scheme using subcarriers including natural number N subcarriers,
A subcarrier control unit capable of changing subcarriers used for the wireless communication from N subcarriers to M (N <M) subcarriers;
A wireless communication apparatus comprising: a spreading factor control unit that performs control to change a spreading factor according to a change in the number of subcarriers.

A1, 81 ... Antenna (first antenna)
A2,82 ... Antenna (second antenna)
A5,62 ... Antenna (first antenna)
A7, 72 ... Antenna (second antenna)
11, 21, reception processing units 12, 22, reception data processing units 13, 23, subcarrier measurement unit 14, reception carrier determination units 15, 24, feedback information processing unit (acquisition means) )
16, 25 ... Feedback information generation unit 17 ... Transmission carrier determination unit (allocation means)
18, 26 ... Transmission data processing unit 19, 27 ... Feedback information adding unit 20, 28 ... Transmission processing unit 50 ... Base station controller (RNC)
51: Data reception unit 52: Data division rate determination unit 53: Data division / transmission unit 60, 70: Base station (Node B)
80: Mobile device (mobile terminal)
90 ... DHO processing part

Claims (3)

A reception processing unit for receiving a signal;
Based on the received signal, a plurality of subcarriers are determined such that the ratio of the assigned subcarrier to the fading occurrence subcarrier is uniform between the branches, and the determined plurality of subcarriers are determined as the received signal. A transmission processing unit for notifying the transmission source of
A mobile terminal comprising: The reception processing unit receives signals on a plurality of subcarriers,
The transmission processing unit determines a plurality of subcarriers based on the reception status of the received signal for each subcarrier so that the ratio between the assigned subcarrier and the fading occurrence subcarrier is uniform between the branches, Notifying the determined plurality of subcarriers to the source of the received signal;
The mobile terminal according to claim 1.   A signal is received, and based on the received signal, a plurality of subcarriers are determined such that the ratio of the assigned subcarriers and the fading occurrence subcarriers is uniform between the branches, and the determined subcarriers are: A mobile terminal comprising a reception processing unit for receiving a signal from a transmission source of the received signal.

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