JP6278045B2 - Wireless communication method, wireless communication system, base station, and wireless station - Google Patents

Description

  The present invention relates to a radio communication method, a radio communication system, a base station, and a radio station.

  In recent years, in the wireless communication system such as a cellular phone system (cellular system), the next generation wireless communication technology has been discussed in order to further increase the speed and capacity of the wireless communication. For example, 3GPP (3rd Generation Partnership Project), a standardization organization, proposes a communication standard called LTE (Long Term Evolution) and a communication standard called LTE-A (LTE-Advanced) based on LTE wireless communication technology. Has been.

  The latest communication standard completed in 3GPP is Release 11 corresponding to LTE-A, which is an extension of Release 10 that greatly expands Release 8 and 9 corresponding to LTE. Currently, the discussion of the major parts of Release 12 that further expands Release 11 is over and details are being finalized. Hereinafter, unless otherwise specified, “LTE” includes, in addition to LTE and LTE-A, other wireless communication systems in which these are expanded.

  3GPP Release 12 includes various technologies. One of those technologies is a small cell. A small cell is a relatively small cell and is a concept for a macro cell that is a relatively large cell. A macro cell is formed by a relatively large radio base station, whereas a small cell is formed by a relatively small radio base station. Here, the “cell” is a term indicating a range covered by the radio base station in order for the radio terminal to transmit and receive radio signals. However, since the radio base station and the cell are almost corresponding concepts, In the description, “cell” may be appropriately read as “radio base station”.

  It is thought that several effects can be obtained by introducing a small cell. For example, the macro cell load can be reduced by arranging the small cell in a place with a large communication amount such as a hot spot. In addition, for a wireless terminal, transmitting signals to a small cell closer to a distant macro cell can suppress the transmission power and can be expected to have an effect of obtaining good communication characteristics. Small cells are considered to be an elemental technology that can solve various problems of current or future wireless communication systems, and active discussions will continue as a promising future technology in 3GPP. There is no mistake.

  By the way, in 3GPP, examination of dual connectivity is started as one of the technologies related to small cells. In the two-way connection, wireless terminals connect to a plurality of wireless base stations and communicate with each other at the same time, thereby transmitting or receiving different information simultaneously with the respective wireless base stations. In other words, according to the two-way connection, the wireless terminal can perform individual communication in parallel with each of the plurality of wireless base stations.

  FIG. 1 shows a conceptual diagram of two-way connection. As shown in FIG. 1, as an example of two-way connection, when a plurality of small cells (cells formed by small base stations) are arranged in a macro cell (cell formed by macro base stations), a wireless terminal A case where (UE: User Equipment) connects to both a macro cell and a small cell is conceivable. As a result, for example, the wireless terminal can transmit and receive information (individual communication) different from both the macro cell and the small cell, so that high-speed communication can be realized. Although discussions regarding two-way connection have just started in 3GPP, many discussions will continue in the future because it will be possible to achieve the high speed and large capacity required for future wireless communication systems. It is expected to be done.

  In this application, two-way connection is described, but it goes without saying that the same discussion can be made for three-way or more multiple access. Therefore, it should be noted that the binary connection in the present application may be regarded as a concept including the multiple connection, and the binary connection may be read as the multiple connection in the present application.

3GPP TS36.300 V11.7.0 (2013-09) 3GPP TS36.211 V11.4.0 (2013-09) 3GPP TS36.212 V11.3.0 (2013-06) 3GPP TS36.213 V11.7.0 (2013-09) 3GPP TS36.321 V11.3.0 (2013-06) 3GPP TS36.322 V11.0.0 (2012-09) 3GPP TS36.323 V11.2.0 (2013-03) 3GPP TS36.331 V11.5.0 (2013-09) 3GPP R2-133292 (2013-10) 3GPP R2-133732 (TR36.842 V0.4.0) (2013-10)

  As described above, in 3GPP, discussions have begun on two-way connections based on small cells, etc., and discussions have not yet been made so deeply. Therefore, when a two-way connection is introduced to an LTE system or the like, there is a possibility that some problem or inconvenience that is unknown in the world may occur. In particular, little research has been conducted on terminal management by a base station for realizing two-way connection. Therefore, a terminal management mechanism that is desirable for realizing a two-way connection based on a small cell or the like has not existed conventionally.

  In addition, although the description up to the above problem has been performed based on a small cell in the LTE system, this problem can be extended to a general cell including a macro cell. That is, a terminal management mechanism that is desirable for a wireless terminal to realize a two-way connection with a plurality of cells in a conventional LTE system has not been known.

  The disclosed technique has been made in view of the above, and provides a wireless communication method, a wireless communication system, a base station, and a wireless station that can perform terminal management desirable when realizing dual connection With the goal.

  In order to solve the above-described problems and achieve the object, the disclosed wireless communication method is such that a base station is a first wireless station that cannot communicate with the base station and other base stations in parallel. The first information to be transmitted is subjected to a first conversion process, and the base station transmits the second information to be transmitted when the second radio station capable of communicating in parallel with the base station and the other base station is the destination. On the other hand, a second conversion process different from the first conversion process is performed.

  According to one aspect of the wireless communication method, the wireless communication system, the base station, and the wireless station disclosed in this case, it is possible to perform terminal management that is desirable when two-way connection is realized.

FIG. 1 is a diagram illustrating the concept of two-way connection. FIG. 2 is an example of a processing flow showing an overview of DCI transmission processing according to the LTE system. FIG. 3 is an example of a processing flow showing an outline of the DCI reception processing according to the LTE system. FIG. 4 is an example of a processing flow showing an overview of DCI transmission processing according to the second embodiment. FIG. 5 is an example of a process flow showing an overview of the DCI reception process according to the second embodiment. FIG. 6 is an example of a processing flow showing details of DCI transmission processing according to the LTE system. FIG. 7 is a diagram illustrating an example of a network configuration of the wireless communication system according to each embodiment. FIG. 8 is a diagram illustrating an example of a functional configuration of the radio base station in each embodiment. FIG. 9 is a diagram illustrating an example of a functional configuration of a wireless terminal in each embodiment. FIG. 10 is a diagram illustrating an example of a hardware configuration of a radio base station in each embodiment. FIG. 11 is a diagram illustrating an example of a hardware configuration of a wireless terminal in each embodiment.

  Hereinafter, embodiments of the disclosed wireless communication method, wireless communication system, base station, and wireless station will be described with reference to the drawings. In addition, although demonstrated as separate embodiment for convenience, it cannot be overemphasized that the effect of a combination can be acquired and usefulness can further be heightened by combining each embodiment.

[Location of problem]
First, before describing each embodiment, the location of problems in the prior art will be described. It should be noted that this problem has been newly found as a result of careful study of the prior art by the inventor and has not been known so far.

  As described above, the terminal management desirable for the wireless terminal 20 to realize a two-way connection with a plurality of cells in the conventional LTE system is not known. In the following, this point will be examined as to whether terminal management desirable for realizing a two-way connection is possible by using the technology already defined in the conventional LTE system.

  As preparation for the examination, transmission / reception processing of downlink control information from the base station 10 to the radio terminal 20 in the conventional LTE system will be described below as an example. In the LTE system, the radio terminal 20 is generally referred to as UE (User Equipment), and the base station 10 (radio base station 10) is referred to as eNB (evolved Node B). It should be noted that the wireless terminal 20 in the present application can be generalized as a wireless station. The wireless station can include a wireless communication device that can perform wireless communication with the base station 10.

  The base station 10 transmits DCI (Downlink Control Information), which is downlink control information, to the terminal in a predetermined case. For example, when transmitting the downlink data, the base station 10 transmits the downlink data with the DCI attached. At this time, the DCI includes various control information for the wireless terminal 20 to receive downlink data. Further, for example, the base station 10 transmits DCI even when the terminal transmits uplink data. The DCI in this case is called UL Grant and includes various control information for the wireless terminal 20 to transmit uplink data. Further, for example, DCI may be used to control transmission power in the terminal. Thus, DCI can be said to be essential control information for performing wireless communication such as data communication between the base station 10 and the terminal.

  DCI was previously sent and received via the downlink control channel (PDCCH: Physical Downlink Control CHannel), but it was sent and received via the EPDCCH (Enhanced Physical Downlink Control CHannel) introduced in release 11 of 3GPP. You can also. On the other hand, downlink data is transmitted via a downlink shared channel (PDSCH: Physical Downlink Shared CHannel), uplink data is transmitted via an uplink shared channel (PUSCH: Physical Uplink Shared CHannel), and uplink control information is transmitted via an uplink control channel (PUCCH: Physical Uplink). Control CHannel).

  A DCI is added with a 16-bit CRC so that the radio terminal 20 can determine whether or not the DCI is received correctly. Here, the CRC added to the DCI is masked with a C-RNTI (Cell Radio Network Temporary Identifier) which is an identifier of the radio terminal 20 in data communication.

  In the LTE system, a logical and temporary terminal identifier called RNTI (Radio Network Temporary Identifier) is used, and C-RNTI corresponds to the identifier of the radio terminal 20 in data communication among the RNTI. . C-RNTI is a 16-bit identifier (however, a part of the 16-bit space cannot be used as C-RNTI), and the radio terminal 20 performs random access for synchronizing uplink with the base station 10 (cell). In the procedure, the C-RNTI is allocated from the base station 10. Each base station 10 independently assigns a C-RNTI to each subordinate radio terminal 20 uniquely (so as not to overlap between the subordinate radio terminals 20). When the radio terminal 20 moves and becomes under the control of another base station 10, the radio terminal 20 receives a new C-RNTI assignment from the destination base station 10.

  Based on FIG. 2, the outline of the DCI transmission processing by the base station 10 in the LTE system will be described. Note that FIG. 2 shows an outline of DCI transmission processing in the LTE system, and a part of the procedure is omitted for the sake of simplicity.

  First, in S101, the base station 10 generates a DCI. As described above, for example, when downlink data to be transmitted to the radio terminal 20 is generated in the base station 10, a DCI associated with the downlink data is generated. However, the DCI generated in S101 is not limited to this, and any DCI may be used.

  In step S102, the base station 10 adds a 16-bit CRC to the DCI as described above. As described above, the CRC is masked by the C-RNTI of the wireless terminal 20 that is the destination of the DCI. In the present application, for convenience, the CRC after masking will be referred to as masked CRC. The reason for masking CRC based on C-RNTI is to prevent erroneous reception between terminals.

  Next, in S103, the base station 10 performs scrambling on the DCI and the masked CRC. This scrambling is performed based on PCI (Physical Cell Identifier) which is an identifier (cell ID) of the base station 10. More specifically, the base station 10 generates a scrambling sequence (a pseudo-random sequence called a gold code) based on the PCI of the base station 10 itself, and scrambles the DCI and the masked CRC based on the scrambling sequence. To do. PCI is repeatedly assigned to each base station 10 in advance from 504 types of values by an operator, but different values are assigned to adjacent base stations 10 such as the macro base station 10a and the small base station 10b, for example. The reason why the DCI and the masked DCI are scrambled based on the PCI is to prevent the interference between the base stations 10.

  In step S104, the base station 10 transmits the DCI and the masked CRC scrambled in step S103 to the destination wireless terminal 20, respectively. As described above, DCI is transmitted / received via either PDCCH or EPDCCH. For example, when the PDCCH is used, the scrambled DCI and the masked CRC are mapped and transmitted in the control signal area provided in the head part of the downlink subframe.

  Based on FIG. 3, an outline of DCI reception processing by the radio terminal 20 in the LTE system will be described. Note that FIG. 3 shows an outline of DCI reception processing in the LTE system, and a part of the procedure is omitted for the sake of simplicity.

  First, the premise of FIG. 3 will be described. The wireless terminal 20 does not recognize when the DCI addressed to itself is transmitted (that is, in which downlink subframe). Therefore, the radio terminal 20 needs to monitor the control signal areas of all downlink subframes and decode all DCIs (more precisely DCI candidates) mapped there. Since decoding of DCI is performed blindly in this way, it is generally called blind decoding.

  In S201 of FIG. 3, the radio terminal 20 selects one DCI (DCI candidate) to which a masked CRC is added in the control signal region of the downlink subframe received from the base station 10. In this application, for convenience, the DCI and masked CRC received by the wireless terminal 20 from the base station 10 are referred to as reception DCI and reception masked CRC.

  Next, in S202, the wireless terminal 20 performs descrambling (that is, unscrambling) the reception DCI and reception masked CRC selected in S201. Specifically, the radio terminal 20 performs descrambling on the reception DCI and the reception masked CRC based on the PCI that is the identifier (cell ID) of the base station 10. This descrambling corresponds to the inverse transform of the scrambling performed by the base station 10 in S103 of FIG. 2, so that the scrambling applied to the reception DCI and the reception masked CRC can be solved. In order to perform descrambling here, the wireless terminal 20 needs to recognize the PCI of the base station 10, but the wireless terminal 20 has a PSS (Primary Synchronization Signal) and a synchronization signal of the base station 10. PCI can be recognized in advance by SSS (Secondary Synchronization Signal).

  In step S203, the wireless terminal 20 performs a CRC check based on the reception DCI and reception masked DCI descrambled in step S202. More specifically, in S203, the wireless terminal 20 generates a CRC (referred to as a first CRC for convenience) based on the received DCI descrambled in S202. Also, the reception masked CRC descrambled in S202 is demasked (unmasking) with its own C-RNTI, and the unmasked CRC (referred to as a second CRC for convenience) is obtained. Then, the radio terminal 20 compares the first CRC and the second CRC. If they match, the DCI is successfully received, and the wireless terminal 20 determines that the DCI is addressed to itself. On the other hand, if they do not match, the DCI fails to be received, and the first terminal determines that the DCI is not addressed to itself.

  In S204, the radio terminal 20 determines whether undecoded DCI (candidate) remains in the control signal area of the downlink subframe. If undecoded DCI remains, the process returns to S201. If there remains no undecoded DCI, the DCI reception process ends.

  The above is the transmission / reception process of the downlink control information from the base station 10 to the radio terminal 20 in the conventional LTE system. In the following, the discussion is returned to the original, and management of the radio terminal 20 that is desirable for realizing dual connection in the LTE system will be described based on the above description.

  First, the premise of the discussion is described. As described above, some wireless terminals 20 are capable of two-way connection. Here, it is assumed that even if the wireless terminal 20 is two-way connected, the number of C-RNTIs assigned to the wireless terminal 20 is one (or “unique”). In other words, the wireless terminal 20 receives downlink data addressed to itself based on the same C-RNTI in each of the two-way connections. In this application, for convenience, the wireless terminal 20 that cannot be connected in two ways is referred to as a first wireless terminal 20a, and the wireless terminal 20 that can be connected in two ways is referred to as a second wireless terminal 20b.

  Now, the second radio terminal 20b, which is a radio terminal 20 that can be connected in two ways, is connected to the macro base station 10a (macro cell), and the second radio terminal 20b can transmit and receive uplink data and downlink data to and from the macro base station 10a. It shall be in a possible state (called RRC-Connected state in LTE system). At this time, the second radio terminal 20b is assigned # N1 as C-RNTI from the macro base station 10a.

  Next, it is assumed that the second radio terminal 20b is connected to the small base station 10b (small cell) while maintaining the connection of the macro base station 10a. That is, it is assumed that the second radio terminal 20b is connected in two ways to the macro base station 10a and the small base station 10b. For example, the second radio terminal 20b reports the reception quality from the small base station 10b to the macro base station 10a, and the macro base station 10a decides to connect the second radio terminal 20b in a two-way connection based on the reception quality. Then, the wireless terminal 20 is notified of the determination. Thereafter, the second radio terminal 20b performs a predetermined procedure with the small base station 10b, and connects to the small base station 10b while maintaining the connection with the macro base station 10a.

  At this time, the macro base station 10a notifies the small base station 10b of # N1, which is C-RNTI already assigned to the second radio terminal 20b. As described above, it should be noted that in the discussion here, even a wireless terminal 20 that performs a two-way connection has one C-RNTI. The small base station 10b can transmit the DCI to the second radio terminal 20b by receiving the C-RNTI of the second radio terminal 20b from the macro base station 10a. As a result, the small base station 10b can perform data communication with the second radio terminal 20b.

  With the above procedure, two-way connection is realized in the second radio terminal 20b, and the second radio terminal 20b can receive DCI from each of the macro base station 10a and the small base station 10b. As a result, the second radio terminal 20b can perform data communication in parallel between the macro base station 10a and the small base station 10b.

  However, the above procedure is sufficient if the wireless terminal 20 connected to the small base station 10b is only the second wireless terminal 20b, but other wireless terminals 20 are also connected to the small base station 10b. There is room for the following problems to occur.

  In the following, it is assumed that the PCI (cell ID) of the macro base station 10a and the PCI of the small base station 10b are # M1 and # M2, respectively.

  Now, assume that when the second radio terminal 20b is connected to the small base station 10b, the second radio terminal 20b is already connected to the small base station 10b. Here, it is assumed that the second radio terminal 20b is a radio terminal 20 different from the second radio terminal 20b, and as an example, is a radio terminal 20 incapable of two-way connection (such a radio terminal 20 as a legacy radio). May be referred to as a terminal 20). At this time, there is a possibility that the small base station 10b has already assigned # N1 as C-RNTI to the second radio terminal 20b. Thereby, C-RNTI is established between the second radio terminal 20b that performs a two-way connection to the macro base station 10a and the small base station 10b and the second radio terminal 20b that connects to the small base station 10b. Duplication itself may occur.

  In such a situation, for example, consider a case where the small base station 10b transmits a DCI addressed to the second radio terminal 20b. In that case, the DCI is added with a CRC masked by # N1 which is the C-RNTI of the second radio terminal 20b along with the processing flow of FIG. 2, and then the PCI is # M2 which is the PCI of the small base station 10b. Scrambled and transmitted.

  At this time, the first radio terminal 20a descrambles the reception DCI and the reception masked CRC with # M2 and further demasks the reception masked CRC after descrambling with # N1 according to the processing flow of FIG. Perform CRC check at. Here, since the conversion process (masking and scrambling) for DCI by the small base station 10b and the conversion process (descrambling and demasking) for the received DCI by the first radio terminal 20a are inversely converted, the first radio terminal 20a performs a CRC check based on the DCI and CRC before the small base station 10b performs the conversion process. Therefore, in this case, unless an unacceptable radio error occurs on the radio, the CRC check is successful (successful reception), and the first radio terminal 20a can appropriately receive the DCI addressed to itself.

  On the other hand, the DCI reception process by the second wireless terminal 20b in the first case is considered. At this time, the second wireless terminal 20b also descrambles the reception DCI and the reception masked CRC with # M2 and further demasks the reception masked CRC after descrambling with # N1 in accordance with the processing flow of FIG. Perform CRC check. Here, as described above, it should be noted that the C-RNTI of the second radio terminal 20b and the C-RNTI of the first radio terminal 20a overlap, and both are # N1. At this time, since the conversion process for the DCI by the small base station 10b and the conversion process for the reception DCI by the second radio terminal 20b are also inversely converted, the second radio terminal 20b is in a state before the small base station 10b performs the conversion process. CRC check is performed based on DCI and CRC. Therefore, in this case, the CRC check is successful (successful reception), and the second wireless terminal 20b improperly receives the DCI addressed to the first wireless terminal 20a (that is, erroneous reception occurs).

  From the above, when the C-RNTI overlaps, the DCI addressed to the first radio terminal 20a is received redundantly by the first radio terminal 20a and the second radio terminal 20b. At this time, the second radio terminal 20b erroneously receives the DCI addressed to the other radio terminal 20. In such a case, since the second wireless terminal 20b erroneously performs reception of downlink data, transmission of uplink data, etc. associated with the DCI based on erroneous reception of DCI, such as erroneous reception, erroneous transmission, etc. A malfunction will occur. Therefore, such duplicate reception of DCI is considered to be a very undesirable problem for a wireless communication system.

  In the above, as an example, the erroneous reception that occurs in the second radio terminal 20b when the small base station 10b transmits the DCI to the second radio terminal 20b has been described, but the small base station 10b is addressed to the second radio terminal 20b. When the DCI is transmitted to the second wireless terminal 20b, the same erroneous reception may occur. On the other hand, when the macro base station 10a transmits a DCI addressed to the second radio terminal 20b, the same erroneous reception does not occur in the second radio terminal 20b. The C-RNTI of the second radio terminal 20b is # N1, but the second radio terminal 20b is not connected to the macro base station 10a. Therefore, the first radio terminal 20a does not perform the process (descrambling based on # M1) for receiving the DCI scrambled by # M1, which is the PCI (cell ID) of the macro base station 10a.

  In the above description, the problem of duplicate reception based on duplication of C-RNTI has been described. However, it should be noted that the present invention is not limited to this. There are other types of RNTI, which is a terminal identifier in the LTE system, other than C-RNTI, and among these, there are some that should be assigned without overlapping between base stations 10. In addition to C-RNTI, RNTI that should be allocated between base stations 10 includes Semi-Persistent Scheduling C-RNTI, Temporary C-RNTI, TPC-PUCCH-RNTI, and TPC-PUSCH-RNTI.

  Furthermore, in the above description, it has been based on a binary connection between the macro base station 10a (macro cell) and the small base station 10b (small cell) in the LTE system, but the scope of application of the present invention is not limited to this, Note that it can be extended to a general base station 10 (cell). For example, the present invention is naturally applicable to master cells and slave cells, anchor cells and assisting cells, primary cells and secondary cells, and the like. Further, in the present application, it should be noted that the name of each cell (base station 10) is not limited to these. In general, the base station 10 is a base station 10 that performs communication by connecting both a control plane and a data plane as in a conventional LTE communication system, and a base that performs communication by additionally connecting a data plane. If the base station 10 is a subordinate station 10, various names can be used without departing from this intention. For example, in the latest standardization trend, a combination of two-way connection and carrier aggregation is possible. The cell group that provides the main communication resource is the “master cell group (MCG)”, and the cell group that provides the additional communication resource is It is called “Secondary Cell Group (SCG)”.

  In addition, although the above has been described with reference to an LTE system, it should be noted that the above problems are not limited to LTE systems. That is, the above problem can occur in any wireless communication system as long as conditions are met.

  In summary, as an example, in the LTE system, each base station 10 uniquely assigns a C-RNTI, which is a terminal identifier, to each subordinate radio terminal 20 (so as not to overlap between subordinate radio terminals 20. ) Allocation, the radio terminal 20 receives the DCI addressed to itself from the base station 10 based on the C-RNTI allocated to itself. Here, on the assumption that each wireless terminal 20 receives DCI from only one base station 10 as in the prior art, DCI is received only by the destination wireless terminal 20 due to the uniqueness of C-RNTI in the base station 10. Was secured. However, when there are wireless terminals 20 that receive DCIs from a plurality of base stations 10, the uniqueness of C-RNTI in the base station 10 also ensures that the DCI is received only by the destination wireless terminal 20. It may happen that it disappears. When the DCI is received by another radio terminal 20 different from the destination radio terminal 20, the other radio terminal 20 receives downlink data or uplink data associated with the DCI, and erroneous reception or transmission occurs. Therefore, it is considered not preferable. As described above, this problem was newly found as a result of careful study of the prior art by the inventor, and has not been known so far. Hereinafter, each embodiment of the present application for solving the problem of erroneous reception associated with the two-way connection will be described in order.

[First Embodiment]
In the first embodiment, a base station 10 (for example, a small base station 10b) is a first radio station (for example, binary) that cannot communicate with the base station 10 and another base station 10 (for example, a macro base station 10a) in parallel. When the first wireless terminal 20a) that cannot be connected is a destination, the first information to be transmitted (for example, DCI) is subjected to a first conversion process (for example, scrambling based on the cell ID of the small base station 10b), The base station 10 transmits the second information when the second radio station (for example, the second radio terminal 20b capable of two-way connection) capable of communicating in parallel with the base station 10 and the other base station 10 is the destination. (E.g. DCI) second conversion processing different from the first conversion processing (e.g. scrambling based on the cell ID of the macro base station 10a and scrambling based on the cell ID of the small base station 10b) And it performs double scrambling) made of.

  The first embodiment also includes a first base station 10 (for example, a small base station 10b) that performs first conversion processing (for example, scrambling based on the cell ID of the small base station 10b) on information to be transmitted (for example, DCI), The information to be transmitted includes the first conversion process or a second conversion process different from the first conversion process (for example, scrambling based on the cell ID of the macro base station 10a and scrambling based on the cell ID of the small base station 10). Communication in parallel with a second base station 10 (for example, the macro base station 10a) that performs double scrambling, and the information received from the first base station 10 corresponds to the first conversion process. 1 Decoding process (for example, descrambling based on the cell ID of the small base station 10b) is performed, and the information received from the second base station 10 A wireless communication method for performing a second decoding process corresponding to the second conversion process (for example, double descrambling consisting of descrambling based on the cell ID of the small base station 10b and descrambling based on the cell ID of the macro base station 10a). When the second base station 10 cannot communicate with the first base station 10 and the second base station 10 in parallel with the destination radio station (for example, when it is a terminal incapable of two-way connection). When the destination radio station can perform communication in parallel with the first base station 10 and the second base station 10 while performing the first conversion processing on the information to be transmitted (for example, in a terminal capable of two-way connection) In some cases, the second conversion process is performed on the information to be transmitted.

  Here, the first conversion process for the first information addressed to the first radio station (first radio terminal 20a capable of two-way connection) and the second radio station (second radio terminal 20b that cannot be two-way connection) It should be noted that the second conversion process for the second information may include any different conversion processes that can avoid the reception (interference) of the first information and the second information on the receiving side. However, in view of the location of the above-described problem, even if the identifiers of the first wireless station and the second wireless station are duplicated, the first conversion process that can avoid the duplicate reception of the first information and the second information, It is desirable to employ the second conversion process. In the above description, scrambling based on the cell ID of the small base station 10b is cited as the first conversion processing, and scrambling and smoothing based on the cell ID of the macro base station 10a is used as the second conversion processing. Although double scrambling consisting of scrambling based on the cell ID of the base station 10 is mentioned, it goes without saying that these are only examples.

  According to the first embodiment, it is possible to avoid the problem of duplicate reception associated with the above-described two-way connection. This will be described along with a specific example described in the above-mentioned problem location.

  For example, consider a case where the small base station 10b transmits a DCI to the first wireless terminal 20a that is not capable of two-way connection. At this time, according to the DCI transmission process according to the first embodiment, the small base station 10b performs a first conversion process (for example, scrambling based on the cell ID of the small base station 10b) on the DCI. On the other hand, according to the DCI reception process according to the first embodiment, the second wireless terminal 20b capable of two-way connection can perform the second decoding corresponding to the second conversion process different from the first conversion process on the DCI. Process. At this time, since the conversion process on the transmission side does not correspond to the decoding process on the reception side, the decoding process is considered to fail. Accordingly, erroneous reception by the second wireless terminal 20b capable of two-way connection to the DCI addressed to the first wireless terminal 20a that cannot be two-way connected is avoided.

  On the other hand, consider a case where the small base station 10b transmits a DCI to the second wireless terminal 20b capable of two-way connection. At this time, according to the DCI transmission process according to the first embodiment, the small base station 10b performs a second conversion process on the DCI (for example, scrambling based on the cell ID of the macro base station 10a and the cell of the small base station 10b). (Double scrambling consisting of scrambling based on ID). On the other hand, the first wireless terminal 20a that cannot perform the two-way connection performs a first decoding process corresponding to the first conversion process on the DCI. Also at this time, the conversion process on the transmission side does not correspond to the decoding process on the reception side, so the decoding process is considered to fail. Therefore, erroneous reception by the first wireless terminal 20a, which is not capable of two-way connection, with respect to the DCI addressed to the second wireless terminal 20b that is capable of two-way connection is also avoided.

  By the way, in said 1st Embodiment and each subsequent embodiment, although the case where the downlink data in a LTE system was mainly transmitted / received was demonstrated to the example, it applies similarly when transmitting / receiving the uplink data in a LTE system. Note that is possible.

  In the first embodiment and each of the subsequent embodiments, the description is mainly based on the two-way connection between the macro base station 10a (macro cell) and the small base station 10b (small cell) in the LTE system. However, it should be noted that the scope of application of the present invention is not limited to this and can be extended to a general radio base station 10 (cell). For example, the present invention is naturally applicable to master cells and slave cells, anchor cells and assisting cells, primary cells and secondary cells, and the like. Furthermore, in the present application, it should be noted that the name of each cell (radio base station 10) is not limited to these. Generally, a radio base station 10 that performs communication by connecting both a control plane and a data plane as in a conventional LTE communication system is the main radio base station 10, and additionally communicates by connecting a data plane. If the radio base station 10 to be performed is a subordinate radio base station 10, various names can be used without departing from this intention.

  Furthermore, in the first embodiment and each of the following embodiments, it is mainly described based on the LTE system, but it should be noted that the present invention is not limited to the LTE system. In other words, the present invention can be applied to any wireless communication system as long as conditions are met.

  According to the first embodiment described above, as described above, the problem of duplicate reception of DCI described in the location of the problem can be solved. Therefore, according to the first embodiment, it is possible to perform terminal management that is desirable when realizing two-way connection.

[Second Embodiment]
The second embodiment is one of the embodiments in which the first embodiment is specifically applied to the LTE system.

  The premise of 2nd Embodiment is demonstrated. Also in the second embodiment, a wireless communication system conforming to the wireless communication system (that is, the conventional LTE system) described in the above “location of problem” is assumed. Specifically, the wireless communication system according to the second embodiment includes a macro base station 10a, a small base station 10b, a first wireless terminal 20a that is a wireless terminal 20 that cannot be connected in two ways, and a wireless that can be connected in two ways. A second wireless terminal 20b, which is the terminal 20, is provided.

  Also in the second embodiment, similarly to the wireless communication system (conventional LTE system) described in the location of the problem, the macro base station 10a assigns the C-RNTI to the second wireless terminal 20b, and the first wireless terminal 20a The C-RNTI is assigned to the small base station 10b. Therefore, it is assumed that the C-RNTI of the second radio terminal 20b and the C-RNTI of the first radio terminal 20a can overlap. However, in the radio communication system according to the second embodiment, unlike the radio communication system described in the location of the problem, the problem of duplicate reception does not occur. This point will be described later.

  In the following, DCI transmission processing by the small base station 10b according to the second embodiment, DCI transmission processing by the macro base station 10a, DCI reception processing by the terminal (first wireless terminal 20a) that cannot be connected in two ways, and The DCI reception process by a terminal capable of two-way connection (second wireless terminal 20b) will be described in order.

  First, FIG. 4 shows an example of a processing flow of DCI transmission processing by the small base station 10b according to the second embodiment.

  Since S301 to S302 in FIG. 4 may be performed in the same manner as S101 to S102 in FIG. 2, description thereof is omitted. Next, in S303, the small base station 10b determines whether or not the wireless terminal 20 that is the destination of the DCI is capable of two-way connection. When the destination of DCI is a terminal (second wireless terminal 20b) capable of two-way connection, the process proceeds to S304. On the other hand, when the destination of the DCI is a terminal (first wireless terminal 20a) that cannot be connected in two ways, the process proceeds to S305.

  In S304, the small base station 10b performs double scrambling on the DCI and the masked CRC addressed to the terminal (second radio terminal 20b) capable of two-way connection. This point is different from the wireless communication system according to the reference technique described above. It should be noted that the reference technology small base station 10b performs only one scrambling.

  The double scrambling in S304 is performed as follows, for example. First, the small base station 10b performs the first scrambling on the DCI and the masked CRC based on the PCI (cell ID) of the macro base station 10a. Further, the small base station 10b performs the second scrambling on the DCI and the masked CRC that are scrambled once based on the PCI of the small base station 10b (the PCI used for scrambling is different from the first time). Note that). As a result, double scrambling is performed on the DCI and the masked CRC.

  Note that, as the method of scrambling twice performed in S304, the one adopted in the conventional LTE system can be used as in the reference technique described above. In order to perform the first scrambling, the small base station 10b needs to recognize the PCI of the macro base station 10a, but this may be performed by an arbitrary method.

  On the other hand, in S305, the small base station 10b performs scrambling only once for the DCI and the masked CRC addressed to the terminal (first radio terminal 20a) that cannot be connected in two ways. Since S305 in FIG. 4 may be performed in the same manner as S103 in FIG. 2, the description thereof is omitted.

  In this way, in S304, the small base station 10b generates a doubly scrambled DCI and a masked CRC for a terminal (second radio terminal 20b) that can be connected in two ways. On the other hand, in S305, the small base station 10b generates a DCI and a masked CRC that are scrambled once for each terminal (first wireless terminal 20a) that cannot be connected in two ways.

  Finally, in S306 or S307, the small base station 10b transmits the information generated in S304 or S305 to the wireless terminal 20. That is, in S306, the small base station 10b transmits the DCI and the masked CRC that are scrambled twice in S304 to a terminal (second radio terminal 20b) capable of two-way connection. Alternatively, in S307, the small base station 10b transmits the DCI and the masked CRC, each of which is scrambled only once in S305, to a terminal (first wireless terminal 20a) that cannot be connected in a binary manner.

  Next, DCI transmission processing by the macro base station 10a according to the second embodiment will be described. The DCI transmission process by the macro base station 10a according to the second embodiment can be performed, for example, in the same manner as the DCI transmission process (FIG. 2) according to the LTE system described above (which will be described later as a modified example). But other ways are possible). Therefore, detailed description is omitted here. Incidentally, as described above, since the problem of duplicate reception does not occur in the first place based on the DCI transmitted from the macro base station 10a, the DCI transmission processing by the macro base station 10a has no problem even if it is the same as the conventional one. I want to be.

  Next, a DCI reception process performed by the wireless terminal 20 (first wireless terminal 20a) that cannot perform two-way connection according to the second embodiment will be described. The DCI reception process by the first radio terminal 20a according to the second embodiment may be performed in the same manner as the DCI reception process (FIG. 3) according to the LTE system described above. Therefore, detailed description is omitted here. Incidentally, since the first radio terminal 20a corresponds to the so-called legacy radio terminal 20 as described above, it is difficult to perform reception processing other than the above-described DCI reception processing (FIG. 3) related to the LTE system. Please note that.

  Next, FIG. 5 shows an example of a processing flow of DCI reception processing by the wireless terminal 20 (second wireless terminal 20b) capable of two-way connection according to the second embodiment. This processing flow corresponds to blind decoding (described above) performed for each DCI (more precisely, DCI candidates).

  First, in S401, the second radio terminal 20b selects one DCI (more precisely, a DCI candidate) to which a masked CRC is added in the control signal region of the downlink subframe received from the base station 10. As described above, in the present application, the DCI and masked CRC received by the wireless terminal 20 from the base station 10 are referred to as reception DCI and reception masked CRC. Here, the received DCI corresponds to either a DCI that is scrambled only once or a DCI that is scrambled twice. The reception masked CRC corresponds to either a masked CRC scrambled only once or a masked CRC scrambled twice.

  Next, in S402, the second radio terminal 20b determines whether the base station 10 that is the transmission source of the received DCI and the received CRC is the small base station 10b or the macro base station 10a. When the transmission source of the reception DCI and the reception CRC is the small base station 10b, the process proceeds to S403. On the other hand, when the transmission source of the reception DCI and the reception CRC is the macro base station 10a, the process proceeds to S404.

  Next, in S403, the second wireless terminal 20b doubles the received DCI and the reception masked CRC. Specifically, first, the second radio terminal 20b performs the first descrambling on the reception DCI and the reception masked CRC based on the PCI of the small base station 10b. Further, the second radio terminal 20b performs the descrambling for the second time based on the PCI of the macro base station 10a for the reception DCI and the reception masked CRC each descrambled once (the first time is descrambled). Note that the PCI used is different). As a result, the reception DCI and the reception masked CRC are each descrambled twice. As the descrambling method performed here, the method adopted in the conventional LTE system can be used as in the above-described reference technology.

  When comparing the double scrambling in S304 of FIG. 4 and the double descrambling of S403 in FIG. 5, the order of applying the PCI of the macro base station 10a and the PCI of the small base station 10b is reversed. Please keep in mind. As a result, the double scrambling and the double descrambling are inversely converted to each other, and the double scrambling can be restored by performing the double descrambling on the double scrambled DCI.

  On the other hand, in S404, the second radio terminal 20b descrambles the received DCI and the received CRC only once (unscrambles). Specifically, the second radio terminal 20b performs descrambling on the received DCI and the received CRC based on the PCI (cell ID) of the macro base station 10a. The descrambling performed here corresponds to the inverse conversion of scrambling performed in the base station 10. As the descrambling method here, a method adopted in the conventional LTE system can be used as in the above-described reference technique.

  In this way, in S403, the second radio terminal 20b performs descrambling twice on the reception DCI and the reception masked CRC received from the small base station 10b. On the other hand, in S404, the second radio terminal 20b descrambles the received DCI and the received masked CRC received from the macro base station 10a only once.

  Finally, in S405 or S406, the second wireless terminal 20b performs a CRC check based on the information generated in S403 or S404. More specifically, in S405, the second radio terminal 20b generates a CRC based on the received DCI that has been double-descrambled in S403, and masks the CRC with its own C-RNTI. Then, the masked CRC is compared with the reception masked CRC double-descrambled in S403. If they match, the DCI is successfully received, and the first terminal determines that the DCI is addressed to itself. On the other hand, if they do not match, the DCI fails to be received, and the first terminal determines that the DCI is not addressed to itself.

  In S406, the second radio terminal 20b generates a CRC based on the received DCI descrambled once in S404, and masks the CRC with its own C-RNTI. Then, the masked CRC is compared with the reception masked CRC descrambled only once in S404. If they match, the DCI is successfully received, and the first terminal determines that the DCI is addressed to itself. On the other hand, if they do not match, the DCI fails to be received, and the first terminal determines that the DCI is not addressed to itself.

  Finally, in S407, the second radio terminal 20b determines whether or not undecoded DCI (candidate) remains in the control signal area of the downlink subframe. If undecoded DCI remains, the process returns to S401. If there remains no undecoded DCI, the DCI reception process ends.

  Hereinafter, it is confirmed that the above-described problem is solved by the transmission / reception processing of the second embodiment described above. Now, in the same way as described in the location of the problem, the second wireless terminal 20b that performs a two-way connection to the macro base station 10a and the small base station 10b, and the second wireless terminal that connects to the small base station 10b It is assumed that C-RNTI = # N1 overlaps with 20b.

  In such a situation, a case where the small base station 10b transmits a DCI addressed to the second radio terminal 20b is considered as a first case. In that case, the DCI is added with a CRC masked with # N1 (which overlaps with the first radio terminal 20a), which is the C-RNTI of the second radio terminal 20b, along the processing flow of FIG. The scrambled doubly is transmitted by # M1 which is PCI of the macro base station 10a and # M2 which is PCI of the small base station 10b.

  In the first case, the second wireless terminal 20b performs reception descrambling after double descrambling after performing descrambling of reception DCI and reception masked CRC with # M2 and # M1 in accordance with the processing flow of FIG. CRC check is performed after demasking the CRC with # N1. Here, in the first case, since the conversion process for DCI by the small base station 10b and the conversion process for reception DCI by the second radio terminal 20b are inversely related, the second radio terminal 20b The CRC check is performed based on the DCI and CRC before 10b performs the conversion process. Accordingly, in this case, unless an unacceptable radio error occurs on the radio, the CRC check is successful (successful reception), and the second radio terminal 20b can appropriately receive the DCI addressed to itself.

  On the other hand, the reception process by the first wireless terminal 20a in the first case is considered. At this time, the first radio terminal 20a descrambles the reception DCI and the reception masked CRC based on # M2 which is the PCI of the small base station 10b, and then performs the reception masked CRC after descrambling according to the processing flow of FIG. In addition, CRC check is performed after demasking with # N1. Here, in the first case, since the conversion process for DCI by the small base station 10b and the conversion process for reception DCI by the first radio terminal 20a are not inversely related, the first radio terminal 20a The CRC check is not performed based on the DCI and CRC before the station 10b performs the conversion process. Therefore, in this case, the CRC check fails (reception failure), and the first radio terminal 20a cannot properly receive the DCI addressed to the second radio terminal 20b (an erroneous reception can be avoided).

  Next, as a second case, consider a case where the small base station 10b transmits a DCI addressed to the second radio terminal 20b. In that case, the DCI is added with a CRC masked with # N1 (which overlaps with the second radio terminal 20b), which is the C-RNTI of the second radio terminal 20b, along the processing flow of FIG. Then, it is scrambled and transmitted by # M2, which is the PCI (cell ID) of the small base station 10b.

  In the second case, the first wireless terminal 20a descrambles the reception DCI and the reception masked CRC with # M2 and then demasks the reception masked CRC after descrambling with # N1 in accordance with the processing flow of FIG. And then check the CRC. Here, in the second case, since the conversion process for DCI by the small base station 10b and the conversion process for reception DCI by the first radio terminal 20a are inversely related, the first radio terminal 20a The CRC check is performed based on the DCI and CRC before 10b performs the conversion process. Therefore, in this case, unless an unacceptable radio error occurs on the radio, the CRC check is successful (successful reception), and the first radio terminal 20a can appropriately receive the DCI addressed to itself.

  On the other hand, the reception process by the second wireless terminal 20b in the second case is considered. At this time, the second wireless terminal 20b adds the received DCI and the received masked CRC to # M2 which is the PCI of the small base station 10b and # M1 which is the PCI of the macro base station 10a in accordance with the processing flow of FIG. After double descrambling, receive masked CRC after double descrambling is further demasked with # N1 and then CRC check is performed. Here, in the second case, since the conversion process for DCI by the small base station 10b and the conversion process for reception DCI by the second radio terminal 20b are not inversely related, the second radio terminal 20b The CRC check is not performed based on the DCI and CRC before the station 10b performs the conversion process. Therefore, in this case, the CRC check fails (reception failure), and the second wireless terminal 20b can not properly receive the DCI addressed to the first wireless terminal 20a (an erroneous reception can be avoided).

  As described above, according to the second embodiment, unlike the case described in the above problem location, the problem of duplicate reception associated with the two-way connection does not occur.

  Next, specific examples of the above-described double scrambling and double descrambling will be described along the standard specifications of the LTE system.

  FIG. 6 shows DCI transmission processing in a general LTE system. Here, the transmission process in FIG. 6 corresponds to the DCI transmission process in FIG. As described above, in FIG. 2, a part of the procedure of the DCI transmission process is omitted, whereas FIG. 6 shows the whole process of the transmission process. FIG. 6 shows a case where two DCIs are multiplexed as an example, but it goes without saying that the number of DCIs to be multiplexed is not limited to two.

  The DCI transmission process shown in FIG. 6 will be described. First, let the bit sequence of DCI generated by the base station 10 be a_i. At this time, the base station 10 adds a 16-bit CRC to a_i in S501 (CRC attachment). Here, as described above, the CRC added to a_i is a CRC (masked CRC) obtained by masking the CRC calculated based on a_i with the C-RNTI of the destination terminal. Let c_i be a bit sequence with masked CRC added to a_i.

  Next, in S502 (Channel coding), the base station 10 performs channel coding on c_i. At this time, a tailbiting convolutional code is used as an encoding method. Here, the output of the convolutional code is d_k ^ (0), d_k ^ (1), and d_k ^ (2). These are three parity sequences, and the coding rate of the convolutional code is 1/3.

  Next, in S503 (Rate matching), the base station 10 performs rate matching on d_k ^ (0), d_k ^ (1), and d_k ^ (2). The rate matching in S503 further includes interleave processing in S5031 (Sub-block interleaver), bit combination in S5032 (Bit collection), and bit selection and pruning processing in S5033 (Bit selection and pruning). In the interleaving process of S5031, each bit string of d_k ^ (0), d_k ^ (1), d_k ^ (2) is shuffled, and three bit sequences v_k ^ (0), v_k ^ (1), Generate v_k ^ (2). In the bit combination of S5032, v_k ^ (0), v_k ^ (1), and v_k ^ (2) are combined to generate one bit sequence w_k. In the bit selection and pruning in S5033, bit selection and pruning (decimation) are performed on w_k so as to obtain a desired coding rate, and a bit sequence e_k is generated.

  Further, the base station 10 assigns e_k to a CCE (Control Channel Element) based on an aggregation level determined by radio quality or the like. The aggregation level can take values of 1, 2, 4, and 8. For example, when the aggregation level is 4, the base station 10 assigns e_k to four CCEs.

  In step S504 (Physical channel processing), the base station 10 performs physical channel processing on the transmission side for e_k and transmits the result using a radio signal. The transmission side physical channel processing in S504 further includes S5041 (Multiplexing and scrambling) multiplexing and scrambling, S5042 (Modulation) modulation, S5043 (Layer mapping and precoding) layer mapping and precoding, and S5044 (RE mapping). ) To each RE (Resource Element) mapping process. In the multiplexing and scrambling of S5041, scrambling is performed based on PCI (cell ID) after multiplexing e_k assigned to CCE. The scrambling in S5041 will be described later. The bit sequence after scrambling is modulated with QPSK in S5042, and then mapped to a layer (a communication path by spatial multiplexing) in S5043, and further mapped to RE, which is a radio resource unit on the radio signal, in S5044. Then, the base station 10 transmits the radio signal.

  On the other hand, the detailed DCI reception process can be performed by a process opposite to the detailed DCI transmission process shown in FIG. Therefore, the explanation is omitted here.

Now, scrambling (S5041) in the physical channel processing on the transmission side will be described. Now, let b (i) be a bit string obtained by multiplexing e_k assigned to CCE. At this time, in the LTE standard specification, the bit string after scrambling is expressed by the following equation (1).

  Here, c (i) is a scrambling sequence called a scrambling sequence, and a pseudo-random sequence called a gold code (gold sequence) is used. By using the Gold code, the DCI is randomized by scrambling, so that a stable operation of the demodulator can be obtained on the receiving side.

The scrambling sequence for DCI is defined by a predetermined formula (omitted in this application), and its initial value is defined by the following formula (2). The scrambling sequence is initialized for each subframe based on this initial value.

  Here, N_ID ^ cell corresponds to PCI which is the identifier (cell ID) of the base station 10. Therefore, it can be seen that scrambling on the transmission side for DCI is performed based on PCI as described above. Also, the descrambling on the receiving side for DCI is an inverse conversion process of scrambling on the transmitting side, and is thus performed based on the same scrambling sequence used in scrambling. Therefore, descrambling is also performed based on PCI.

  In the DCI transmission process in the LTE system described with reference to FIG. 6, the DCI and masked CRC scrambling are performed only once in S5041. Also, in the DCI reception process, descrambling of DCI and masked CRC is performed only once (not shown). In other words, for the sequence e_k, scrambling is performed only once on the transmission side, and descrambling is performed only once on the reception side.

  In contrast, in the second embodiment of the present application, double scrambling and descrambling are performed on the DCI and the masked CRC as described with reference to FIGS. Therefore, in the DCI transmission / reception processing according to the second embodiment of the present application, in addition to scrambling and descrambling once for the sequence e_k in FIG. 6, additional scrambling and desking once again at any timing. It is necessary to perform rambling.

  As an example, this additional scrambling and descrambling can be performed on c_i in FIG. This is equivalent to scrambling the DCI raw bit string itself. As a result, scrambling is performed before rate matching (encoding), so that blind decoding on the receiving side can be performed in accordance with conventional processing.

  As another example, additional scrambling and descrambling can be performed on e_k in FIG. This corresponds to continuous double scrambling for e_k. However, in this case, scrambling is performed after rate matching. In other words, scrambling processing is performed after determination of the aggregation level and CCE placement, which affects the blind decoding on the receiving side. Specifically, since blind decoding is repeated twice on the receiving side, the processing amount of that portion is doubled.

  Therefore, it is considered desirable to perform additional scrambling and descrambling on c_i in FIG. On the other hand, it is considered that it is not so realistic to perform additional scrambling and descrambling on e_k in FIG. For example, additional scrambling or descrambling may be performed on any of d_k, v_k, and w_k in FIG. When additional scrambling or the like is performed on d_k or v_k, it corresponds to scrambling before rate matching, and can be handled in the same manner as when additional scrambling or the like is performed on c_i. On the other hand, when additional scrambling is performed on w_k, it corresponds to scrambling after rate matching, and can be handled in the same way as when additional scrambling is performed on e_k. .

  According to the second embodiment described above, as described above, the problem of duplicate reception of DCI described in the location of the problem can be solved. Therefore, according to the second embodiment, it is possible to perform terminal management that is desirable when realizing two-way connection.

[Third Embodiment]
The third embodiment is also one of the embodiments in which the first embodiment is specifically applied to the LTE system. The third embodiment has many points in common with the second embodiment. Therefore, in the following, the third embodiment will be described focusing on differences from the second embodiment.

  First, since the premise of the third embodiment is the same as that of the second embodiment, the description thereof is omitted here.

  The DCI transmission process by the small base station 10b according to the third embodiment will be described. The small base station 10b according to the third embodiment performs DCI transmission processing based on a processing flow (FIG. 4) similar to that of the small base station 10b according to the second embodiment. Specifically, the small base station 10b according to the third embodiment may perform the same processing as that described in the second embodiment for S301 to S303 and S305 to S307 in FIG. On the other hand, the small base station 10b according to the third embodiment performs processing different from the content described in the second embodiment for S304 in FIG.

  The process which the small base station 10b which concerns on 3rd Embodiment performs in S304 of FIG. 4 is demonstrated. In S304 of FIG. 4, the small base station 10b according to the third embodiment performs scrambling by bit-inverting the scrambling sequence with respect to the DCI and masked CRC addressed to the two-way connectable terminal (second radio terminal 20b). Do. More specifically, in the normal scrambling for DCI, the above-mentioned predetermined scrambling sequence (using a gold code) is used, but here the scrambling sequence is bit-inverted and then scrambled. It is.

  Here, bit inversion means that 0 and 1 of each bit of the scrambling sequence are inverted. As an example, when the predetermined scrambling sequence described above is 1010111010100011, the scrambling sequence obtained by bit-inversion of this is 0101000101011100. Note that since the pseudo-randomness of the scrambling sequence before inversion is not lost by inverting the bits in this way, the stability of the operation of the demodulator on the receiving side described above is not impaired. I want.

  As a result, the small base station 10b according to the third embodiment performs scrambling by bit-inverting the scrambling sequence for the DCI and masked CRC addressed to a terminal capable of two-way connection (second radio terminal 20b). Will do. On the other hand, the small base station 10b according to the third embodiment performs bit inversion on the scrambling sequence as usual for DCI and masked CRC addressed to a terminal (first wireless terminal 20a) that cannot be connected in two ways. Scrambling).

  On the other hand, a DCI reception process by the wireless terminal 20 (second wireless terminal 20b) capable of two-way connection according to the third embodiment will be described. The second radio terminal 20b according to the third embodiment performs DCI reception processing based on a processing flow (FIG. 5) similar to that of the second radio terminal 20b according to the second embodiment. Specifically, the second wireless terminal 20b according to the third embodiment may perform the same processing as that described in the second embodiment for S401 to S402 and S404 to S407 in FIG. In contrast, the first terminal according to the third embodiment performs a process different from the content described in the second embodiment for S403 in FIG.

  Specifically, in S403 of FIG. 5, the second radio terminal 20b according to the third embodiment performs descrambling on the DCI and masked CRC received from the small base station 10b by bit-inverting the scrambling sequence. . More specifically, in the normal descrambling for DCI, the above-mentioned predetermined scrambling sequence (using a gold code) is used, but here, descrambling is performed after bit-inversion of the scrambling sequence. It is. Since this process is a process corresponding to the scrambling process by the small base station 10b according to the third embodiment described above, a detailed description thereof is omitted.

  Thereby, the two-way connectable terminal (second radio terminal 20b) according to the third embodiment performs descrambling by bit-inverting the scrambling sequence for the DCI and masked CRC received from the small base station 10b. Will do. On the other hand, the second radio terminal 20b according to the third embodiment performs descrambling as usual (without bit inversion of the scrambling sequence) for the DCI and masked CRC received from the macro base station 10a. become.

  In the wireless communication system according to the third embodiment, similarly to the above embodiments, erroneous reception when the small base station 10b transmits a DCI addressed to the second wireless terminal 20b can be avoided. In order to explain this, here, as an example, in the wireless communication system according to the third embodiment, a case where the small base station 10b transmits a DCI addressed to the second wireless terminal 20b is considered.

  In this case, in the scrambling for DCI and masked CRC, a bit-reversed scrambling sequence is used. On the other hand, the first radio terminal 20a uses a scrambling sequence that does not invert bits in descrambling for reception DCI and reception masked CRC. At this time, the conversion process for the DCI by the small base station 10b and the conversion process for the reception DCI by the first radio terminal 20a are not inversely related. Therefore, the first radio terminal 20a does not perform a CRC check based on the DCI and CRC before the small base station 10b performs the conversion process. Therefore, in this case, the CRC check fails (reception failure), and the first radio terminal 20a cannot properly receive the DCI addressed to the second radio terminal 20b (an erroneous reception can be avoided). Note that, in the wireless communication system according to the third embodiment, erroneous reception can be avoided even when the small base station 10b transmits a DCI addressed to the first wireless terminal 20a. Yes (details omitted).

  According to the third embodiment described above, as described above, the problem of duplicate reception of DCI described at the location of the problem can be solved. Therefore, according to the third embodiment, it is possible to perform terminal management that is desirable when two-way connection is realized.

[Fourth Embodiment]
The fourth embodiment is also one of the embodiments in which the first embodiment is specifically applied to the LTE system. The fourth embodiment has many points in common with the third embodiment. Therefore, the following description will focus on differences from the third embodiment in the fourth embodiment.

  First, since the premise of the fourth embodiment is the same as that of the third embodiment, the description thereof is omitted here.

  The small base station 10b according to the third embodiment described above performs scrambling by bit-inverting the scrambling sequence with respect to the DCI and masked CRC addressed to the two-way connectable terminal (second radio terminal 20b). It is. On the other hand, the small base station 10b according to the fourth embodiment performs scrambling by bit-reversing the scrambling sequence with respect to the DCI and masked CRC addressed to the two-way connectable terminal (second radio terminal 20b). Is what you do.

  Further, a terminal capable of two-way connection (second radio terminal 20b) according to the third embodiment performs descrambling by bit-inverting the scrambling sequence with respect to the DCI and masked CRC received from the small base station 10b. It is. In contrast, the second radio terminal 20b according to the fourth embodiment performs descrambling on the DCI and masked CRC received from the small base station 10b by bit-reversing the scrambling sequence.

  Here, the bit inversion means to reverse the order of bits in the scrambling sequence. As an example, when the predetermined scrambling sequence described above is 1010111010100011, the scrambling sequence obtained by bit-reversing this is 1100010101110101. Note that since the pseudo-randomness of the scrambling sequence before the inversion is not lost by reversing the bits in this way, the stability of the operation of the demodulator on the receiving side described above is not impaired. I want.

  Also in the wireless communication system according to the fourth embodiment, it can be explained that erroneous reception that occurs when the small base station 10b transmits a DCI addressed to the second wireless terminal 20b can be avoided as in the third embodiment. . Moreover, it can be explained that erroneous reception is avoided even when the small base station 10b transmits DCI to the second radio terminal 20b. Since this description is the same as that of the third embodiment, details are omitted here.

  According to the fourth embodiment described above, as described above, the problem of duplicate reception of DCI described at the location of the problem can be solved. Therefore, according to the fourth embodiment, it is possible to perform terminal management that is desirable when two-way connection is realized.

[Other Embodiments]
Here, other embodiments and modifications will be briefly described.

  First, as described in the first embodiment, the first conversion processing for the first information (DCI) addressed to the first radio station (terminal capable of two-way connection) and the second radio station (radio that cannot be two-way connected) As the second conversion process for the second information (DCI) addressed to the terminal 20), the reception side (first radio station or second radio station) can avoid receiving the first information and the second information redundantly (interference). Any different conversion process can be included. However, in view of the location of the above-described problem, even if the identifiers of the first wireless station and the second wireless station are duplicated, the first conversion process that can avoid the duplicate reception of the first information and the second information, It is desirable to employ the second conversion process.

  Although specific examples of the first conversion process and the second conversion process have been described in the second to fourth embodiments, specific examples other than these are also conceivable. For example, in the second embodiment, the double scrambling of S304 in FIG. 4 indicates the first conversion process, and the (single) scrambling of S305 indicates the second conversion process. Here, both the double scrambling of S304 and the scrambling of S305 are performed based on a predetermined formula defined in the conventional LTE system including the formulas (1) and (2) described above. . Further, the double scrambling of S304 is performed based on the PCI of each of the macro base station 10a and the small base station 10b, and the scrambling of S305 is performed based on the PCI of the small base station 10b. However, these can be modified as follows, for example.

  For example, the small base station 10b performs, as the first conversion process in S304 of FIG. 4, a predetermined expression (for convenience, the predetermined expression defined in the conventional LTE system including Expression (1) and Expression (2) described above. The scrambling is performed based on an expression different from the predetermined expression. Note that it is desirable that a pseudo-random sequence be generated in an expression different from the predetermined expression as well as in the predetermined expression. On the other hand, the small base station 10b performs scrambling based on the predetermined formula as a second conversion process in S305 of FIG. 4 (general method). In this way, an embodiment in which the equations that serve as the basis for scrambling in the first conversion process and the second conversion process are different is also possible. This is because the above-described problem of duplicate reception can be avoided.

  As another example, the small base station 10b converts not the PCI (cell ID) itself of the small base station 10b itself but the PCI of the small base station 10b according to a predetermined rule (predetermined) as the first conversion process in S304 of FIG. Scrambling is performed based on another PCI generated by performing arithmetic operations or bit operations). On the other hand, the small base station 10b performs scrambling as a second conversion process in S305 of FIG. 4 based on the PCI of the small base station 10b (general method). In this case, the predetermined formula may be used in any scrambling of the first conversion process and the second conversion process. As described above, an embodiment in which scrambling in the first conversion process and the second conversion process is performed based on different PCIs is also possible. This is because the above-described problem of duplicate reception can be avoided.

  As another example, the small base station 10b performs scrambling as a first conversion process in S304 of FIG. 4 based on the PCI of the small base station 10b and a predetermined formula (general method). On the other hand, the small base station 10b does nothing as the second conversion process in S305 of FIG. Here, it should be noted that the first conversion process and the second conversion process in the present application can be handled as a concept including not performing anything. Thus, an embodiment in which nothing is performed in one of the first conversion process and the second conversion process is also possible. This is because the above-described problem of duplicate reception can be avoided.

  Next, in each of the above-described embodiments, a case has been described in which DCI that is downlink control information is transmitted / received via PDCCH that is a downlink control channel. However, as described above, DCI can be transmitted and received via EPDCCH, which is an extended downlink control channel. In this regard, the present invention is not limited to the case where the DCI is transmitted / received via the PDCCH, and can be applied without any problem when the DCI is applied to the EPDCCH. Specifically, since it is feasible to replace “PDCCH” with “EPDCCH” in each of the above-described embodiments, details are omitted. It should be noted that DCI addressed to multiple users is multiplexed when DCI is transmitted using PDCCH, but is not multiplexed when transmitted using EPDCCH.

  Further, in each of the above-described embodiments, as described in the second embodiment, the DCI transmission process by the macro base station 10a is performed in the same manner as the DCI transmission process (FIG. 2) related to the LTE system described above. I was trying. However, in each of the above embodiments, the macro base station 10a can also be modified to transmit DCI in the same procedure as the small base station 10b. Specifically, for example, in the second embodiment, the macro base station 10a can perform DCI transmission processing along the processing flow of FIG. In this case, the DCI reception process by the two-way connectable radio terminal 20 (second radio terminal 20b) is different from the process flow of FIG. Specifically, the second radio terminal 20b doubles descrambles the received DCI regardless of whether the DCI transmission source is the macro base station 10a or the small base station 10b. As a case where such a modification is applied, for example, the macro base station 10a may behave as the small base station 10b, and the corresponding small base station 10b may behave as the macro base station 10a.

  Finally, it goes without saying that the information element names, parameter names, etc. in the control signals transmitted and received by the radio base station 10 and the radio terminal 20 in the above embodiments are merely examples. Further, even when the arrangement (order) of parameters is different, or when optional (optional) information elements and parameters are not used, they are included in the scope of the present invention as long as they do not depart from the spirit of the present invention. Needless to say.

[Network configuration of wireless communication system of each embodiment]
Next, based on FIG. 7, the network configuration of the radio communication system 1 of each embodiment will be described. As illustrated in FIG. 7, the wireless communication system 1 includes a wireless base station 10 and a wireless terminal 20. The radio base station 10 forms a cell C10. The radio terminal 20 exists in the cell C10.

  The wireless base station 10 is connected to the network device 3 via a wired connection, and the network device 3 is connected to the network 2 via a wired connection. The radio base station 10 is provided so as to be able to transmit / receive data and control information to / from other radio base stations 10 via the network device 3 and the network 2.

  The radio base station 10 may separate the radio communication function with the radio terminal 20 and the digital signal processing and control function to be a separate device. In this case, a device having a wireless communication function is called an RRH (Remote Radio Head), and a device having a digital signal processing and control function is called a BBU (Base Band Unit). The RRH may be installed overhanging from the BBU, and may be wired by an optical fiber between them. Further, the radio base station 10 is a radio of various scales other than small radio base stations 10 (including a micro radio base station 10, a femto radio base station 10 and the like) such as a macro radio base station 10 and a pico radio base station 10. It may be the base station 10. When a relay station that relays wireless communication between the wireless base station 10 and the wireless terminal 20 is used, the relay station (transmission / reception with the wireless terminal 20 and its control) is also included in the wireless base station 10 of the present application. It is good.

  On the other hand, the wireless terminal 20 communicates with the wireless base station 10 by wireless communication.

  The wireless terminal 20 may be a wireless terminal 20 such as a mobile phone, a smartphone, a PDA (Personal Digital Assistant), a personal computer (Personal Computer), various devices or devices (such as a sensor device) having a wireless communication function. Further, when a relay station that relays radio communication between the radio base station 10 and the radio terminal 20 is used, the relay station (transmission / reception with the radio base station 10 and its control) is also included in the radio terminal 20 of this paper. It is good.

  The network device 3 includes, for example, a communication unit and a control unit, and these components are connected so that signals and data can be input and output in one direction or in both directions. The network device 3 is realized by a gateway, for example. As a hardware configuration of the network device 3, for example, the communication unit is realized by an interface circuit, and the control unit is realized by a processor and a memory.

  In addition, the specific mode of distribution / integration of each component of the radio base station 10 and the radio terminal 20 is not limited to the mode of the first embodiment, and all or a part thereof can be used for various loads, usage conditions, and the like. Accordingly, it may be configured to be functionally or physically distributed / integrated in an arbitrary unit. For example, the memory may be connected as an external device of the radio base station 10 and the radio terminal 20 via a network or a cable.

[Functional Configuration of Each Device in Radio Communication System of Each Embodiment]
Next, based on FIGS. 8-9, the function structure of each apparatus in the radio | wireless communications system of each embodiment is demonstrated.

  FIG. 8 is a block diagram illustrating an example of a functional configuration of the radio base station 10 (including the macro base station 10a and the small base station 10b). As illustrated in FIG. 8, the radio base station 10 includes, for example, a radio transmission unit 11, a radio reception unit 12, a control unit 13, a storage unit 14, and a communication unit 15. Each of these components is connected so that signals and data can be input and output in one direction or in both directions. The wireless transmission unit 11 and the wireless reception unit 12 are collectively referred to as a wireless communication unit 16.

  The wireless transmission unit 11 transmits a data signal and a control signal by wireless communication via an antenna. The antenna may be common for transmission and reception. The radio transmission unit 11 transmits a radio signal (downlink radio signal) to the radio terminal 20. The radio signal transmitted by the radio transmission unit 11 can include arbitrary user data and control information for the radio terminal 20 (encoding and modulation are performed).

  As a specific example of the radio signal transmitted by the radio transmitter 11, each radio base station 10 (including the macro base station 10a and the small base station 10b) in FIG. 2, FIG. 4, and FIG. Each radio signal transmitted to the terminal 20a and the second radio terminal 20b). The radio signal transmitted by the radio transmission unit 11 is not limited to these, and includes any radio signal transmitted from each radio base station 10 to the radio terminal 20 in each of the above embodiments and modifications.

  The wireless receiving unit 12 receives data signals and control signals by wireless communication via an antenna. The radio reception unit 12 receives a radio signal (uplink radio signal) from the radio terminal 20. The radio signal received by the radio reception unit 12 can include arbitrary user data and control information (encoded or modulated) transmitted by the radio terminal 20. The signals received by the wireless reception unit 12 are not limited to these, and in each of the above-described embodiments and modifications, each wireless base station 10 (including the macro base station 10a and the small base station 10b) receives the wireless terminal 20 (first wireless communication). All wireless signals received from the terminal 20a and the second wireless terminal 20b).

  The control unit 13 outputs data and control information to be transmitted to the wireless terminal 20 to the wireless transmission unit 11. The control unit 13 inputs data and control information received from the wireless terminal 20 from the wireless reception unit 12. The control unit 13 inputs and outputs data, control information, programs, and the like with the storage unit 14 described later. The control unit 13 inputs / outputs data and control information transmitted / received to / from the other radio base station 10 and the like with the communication unit 15 described later. In addition to these, the control unit 13 performs various controls in the radio base station 10.

  Specific examples of processing controlled by the control unit 13 include control on signals transmitted and received by each radio base station 10 (including the macro base station 10a and the small base station 10b) in FIGS. And control with respect to each process which each wireless base station 10 is performing is mentioned. The process which the control part 13 controls is not restricted to these, but includes the control regarding all the processes which each radio base station 10 performs by said each embodiment and modification.

  The storage unit 14 stores various information such as data, control information, and programs. The various information stored in the storage unit 14 includes all information that can be stored in each radio base station 10 (including the macro base station 10a and the small base station 10b) in each of the above embodiments and modifications.

  The communication unit 15 transmits / receives data and control information to / from another wireless base station 10 or the like via a wired signal or the like (which may be a wireless signal). Wired signals and the like transmitted and received by the communication unit 15 include all wired signals and the like transmitted and received by each wireless base station 10 from the other wireless base station 10 and the like in the above embodiments and modifications.

  The radio base station 10 may transmit and receive radio signals to / from radio communication devices other than the radio terminal 20 (for example, other radio base stations 10 and relay stations) via the radio transmission unit 11 and the radio reception unit 12. .

  FIG. 9 is a block diagram illustrating an example of a functional configuration of the wireless terminal 20 (including the first wireless terminal 20a and the second wireless terminal 20b). As illustrated in FIG. 9, the wireless terminal 20 includes, for example, a wireless transmission unit 21, a wireless reception unit 22, a control unit 23, and a storage unit 24. Each of these components is connected so that signals and data can be input and output in one direction or in both directions. The wireless transmission unit 21 and the wireless reception unit 22 are collectively referred to as a wireless communication unit 25.

  The wireless transmission unit 21 transmits a data signal and a control signal by wireless communication via an antenna. The antenna may be common for transmission and reception. The radio transmission unit 21 transmits a radio signal (uplink radio signal) to each radio base station 10. The radio signal transmitted by the radio transmission unit 21 can include arbitrary user data, control information, and the like (encoded and modulated) for each radio base station 10. The radio signal transmitted by the radio transmission unit 21 is not limited to these, and the radio terminal 20 (including the first radio terminal 20a and the second radio terminal 20b) in each of the above-described embodiments and modified examples has the radio base station 10 ( Including all radio signals to be transmitted to the macro base station 10a and the small base station 10b).

  The wireless reception unit 22 receives data signals and control signals by wireless communication via an antenna. The radio reception unit 22 receives a radio signal (downlink radio signal) from each radio base station 10. The radio signal received by the radio reception unit 22 can include arbitrary user data, control information, and the like (encoded or modulated) transmitted by each radio base station 10.

  As a specific example of the radio signal received by the radio receiver 22, the radio terminal 20 (including the first radio terminal 20a and the second radio terminal 20b) in FIG. 3 and FIG. 5 is transmitted to the radio base station 10 (macro base station 10a, Each radio signal received from the small base station 10b) is included. The signal received by the wireless reception unit 22 is not limited to these, and includes any wireless signal that the wireless terminal 20 receives from each wireless base station 10 in each of the above embodiments and modifications.

  The control unit 23 outputs data and control information to be transmitted to each radio base station 10 to the radio transmission unit 21. The control unit 23 inputs data and control information received from each radio base station 10 from the radio reception unit 22. The control unit 23 inputs and outputs data, control information, programs, and the like with the storage unit 24 described later. In addition to these, the control unit 23 performs various controls in the wireless terminal 20.

  Specific examples of processing controlled by the control unit 23 include control for signals transmitted and received by the wireless terminal 20 (including the first wireless terminal 20a and the second wireless terminal 20b) in FIG. 3 and FIG. The control with respect to each process performed by 20 is mentioned. The process which the control part 23 controls is not restricted to these, but includes the control regarding all the processes which the radio | wireless terminal 20 performs by said each embodiment and modification.

  The storage unit 24 stores various information such as data, control information, and programs. The various information stored in the storage unit 24 includes all information that can be stored in the wireless terminal 20 (including the first wireless terminal 20a and the second wireless terminal 20b) in each of the above-described embodiments and modifications.

  Note that the radio terminal 20 may transmit and receive radio signals to / from radio communication devices other than the radio base station 10 via the radio transmission unit 21 and the radio reception unit 22.

[Hardware Configuration of Each Device in Radio Communication System of Each Embodiment]
Based on FIGS. 10 to 11, the hardware configuration of each device in the wireless communication system of each embodiment and each modification will be described.

  FIG. 10 is a diagram illustrating an example of a hardware configuration of the radio base station 10 (including the macro base station 10a and the small base station 10b). As illustrated in FIG. 10, the radio base station 10 includes, as hardware components, an RF (Radio Frequency) circuit 112 including an antenna 111, a processor 113, a memory 114, and a network IF (Interface) 115, for example. Have. These components are connected so that various signals and data can be input and output via a bus.

  The processor 113 is, for example, a CPU (Central Processing Unit) or a DSP (Digital Signal Processor). In the present application, the processor 113 may be realized by a digital electronic circuit. Examples of the digital electronic circuit include ASIC (Application Specific Integrated Circuit), FPGA (Field-Programming Gate Array), LSI (Large Scale Integration), and the like.

  The memory 114 includes at least one of RAM (Random Access Memory) such as SDRAM (Synchronous Dynamic Random Access Memory), ROM (Read Only Memory), and flash memory, and stores programs, control information, and data. In addition, the radio base station 10 may include an auxiliary storage device (such as a hard disk) not shown.

  The correspondence between the functional configuration of the radio base station 10 illustrated in FIG. 8 and the hardware configuration of the radio base station 10 illustrated in FIG. 10 will be described. The wireless transmission unit 11 and the wireless reception unit 12 (or the wireless communication unit 16) are realized by the RF circuit 112, or the antenna 111 and the RF circuit 112, for example. The control unit 13 is realized by, for example, the processor 113, the memory 114, a digital electronic circuit (not shown), and the like. The storage unit 14 is realized by the memory 114, for example. The communication unit 15 is realized by the network IF 115, for example.

  FIG. 11 is a diagram illustrating an example of a hardware configuration of the wireless terminal 20 (including the first wireless terminal 20a and the second wireless terminal 20b). As illustrated in FIG. 11, the wireless terminal 20 includes, as hardware components, an RF (Radio Frequency) circuit 122 including an antenna 121, a processor 123, and a memory 124, for example. These components are connected so that various signals and data can be input and output via a bus.

  The processor 123 is, for example, a CPU (Central Processing Unit) or a DSP (Digital Signal Processor). In the present application, the processor 123 may be realized by a digital electronic circuit. Examples of the digital electronic circuit include ASIC (Application Specific Integrated Circuit), FPGA (Field-Programming Gate Array), LSI (Large Scale Integration), and the like.

  The memory 124 includes at least one of RAM (Random Access Memory) such as SDRAM (Synchronous Dynamic Random Access Memory), ROM (Read Only Memory), and flash memory, and stores programs, control information, and data.

  The correspondence between the functional configuration of the wireless terminal 20 illustrated in FIG. 9 and the hardware configuration of the wireless terminal 20 illustrated in FIG. 11 will be described. The wireless transmission unit 21 and the wireless reception unit 22 (or the wireless communication unit 25) are realized by the RF circuit 122, the antenna 121, and the RF circuit 122, for example. The control unit 23 is realized by, for example, the processor 123, the memory 124, a digital electronic circuit (not shown), and the like. The storage unit 24 is realized by the memory 124, for example.

1 wireless communication system 2 network 3 network device 10 wireless base station C10 cell 20 wireless terminal

Claims (12)

When the base station is the first wireless station that cannot communicate with the base station and other base stations in parallel, the base station performs a first conversion process on the first information to be transmitted,
When the second radio station capable of communicating in parallel with the base station and the other base station is the destination, the base station performs second conversion processing different from the first conversion processing on the second information to be transmitted. A wireless communication method. The base station performs the first conversion process on the first information after performing the third conversion process based on the first radio station identifier of the first radio station,
2. The radio communication method according to claim 1, wherein the base station performs the second conversion process on the second information after performing the third conversion process based on a second radio station identifier of the second radio station. . The wireless communication method according to claim 2, wherein the first wireless station identifier and the second wireless station identifier can overlap. When the first radio station detects that the first information subjected to the first conversion process has been successfully received based on the first radio station identifier, the first radio station receives the first information. Process as addressed to the station,
When the second wireless station detects that the second information subjected to the second conversion process has been successfully received based on the second wireless station identifier, the second wireless station transmits the second information to the second wireless station. 4. The wireless communication method according to claim 2, wherein the wireless communication method is processed as addressed to a station. The first conversion process includes a conversion process based on a first base station identifier of the base station. The second conversion process is a conversion based on the first base station identifier and a second base station identifier of the other base station. The wireless communication method according to claim 1, further comprising a process. The first conversion process includes a scrambling process based on the first base station identifier;
The wireless communication method according to claim 5, wherein the second conversion process includes a scrambling process based on the first base station identifier and a scrambling process based on the second base station identifier. The first conversion process includes a conversion process based on a first base station identifier of the base station,
The wireless communication method according to claim 1, wherein the second conversion process includes a conversion process that is generated based on the first base station identifier and is based on a third base station identifier that is different from the first base station identifier. The first wireless station cannot perform individual communication in parallel with the base station and the other base station,
The wireless communication method according to claim 1, wherein the second wireless station can perform individual communication in parallel with the base station and the other base station. Communication in parallel with a first base station that performs a first conversion process on information to be transmitted and a second base station that performs a second conversion process different from the first conversion process or the first conversion process on information to be transmitted Done
A wireless communication method for performing a first decoding process on information received from the first base station and performing a second decoding process different from the first decoding process on information received from the second base station There,
When the destination wireless station cannot communicate with the first base station and the second base station in parallel, the second base station performs the first conversion process on the information to be transmitted, and the destination wireless station A wireless communication method for performing the second conversion process on information to be transmitted when communication can be performed in parallel with the first base station and the second base station. A base station,
With other base stations,
A first wireless station that cannot communicate in parallel with the base station and the other base station;
A wireless communication system comprising a second wireless station capable of communicating in parallel with the base station and the other base station,
When the first wireless station is a destination, the base station performs a first conversion process on information to be transmitted, and when the second wireless station is a destination, the base station performs the first conversion on the information to be transmitted. The radio | wireless communications system which performs the 2nd conversion process different from a process. A base station,
When the first wireless station that cannot communicate in parallel with the base station and another base station is the destination, the first conversion processing is performed on the information to be transmitted, and the base station and the other base station are performed in parallel. A base station comprising a control unit that performs a second conversion process different from the first conversion process on information to be transmitted when a second wireless station capable of communication is a destination. Communication in parallel with a first base station that performs a first conversion process on information to be transmitted and a second base station that performs a second conversion process different from the first conversion process or the first conversion process on information to be transmitted A communication unit to perform,
A first decoding process corresponding to the first conversion process is performed on the information received from the first base station, and a second corresponding to the second conversion process is performed on the information received from the second base station. A control unit that performs a decryption process,
When the destination wireless station cannot communicate with the first base station and the second base station in parallel, the second base station performs the first conversion process on the information to be transmitted, and the destination wireless station Is a radio station that performs the second conversion process on information to be transmitted when communication can be performed in parallel with the first base station and the second base station.