WO2015063819A1 - Radio communication method, radio communication system, base station, and radio station - Google Patents

Abstract

The objective of the technique disclosed herein is to provide a radio communication method, a radio communication system, a base station and a radio station that can perform a terminal management desirable when a binary connection is carried out. According to the radio communication method disclosed herein, at least one of a first base station or a second base station performs a control such that a first radio station identifier, which the first base station selects from a set of first radio station identifiers and allocates to a first radio station being able to communicate with the first and second base stations in a parallel manner, is not identical with a second radio station identifier, which the second base station selects from a set of second radio station identifiers at least some of which are identical with some of the set of first radio station identifiers and allocates to a second radio station, the first radio station using the first radio station identifier to communicate at least with the first base station, the second radio station using the second radio station identifier to communicate with the second base station.

Description

Wireless communication method, wireless communication system, base station, and wireless station

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

In recent years, next-generation wireless communication technologies have been discussed in order to further increase the speed and capacity of wireless communication in wireless communication systems such as cellular phone systems (cellular systems). 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, which is a significant enhancement of Release 8 and 9 corresponding to LTE. Currently, the discussion of the main parts of Release 12, which is an extension of 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, but one of those technologies is a small cell. A small cell is a relatively small cell, and is a concept for a macro cell, which is a relatively large cell. A macro cell is formed by a relatively large base station (here, it means area coverage or device size), whereas a small cell is formed by a relatively small base station (here, it means area coverage or device size). It is formed. Here, “cell” is a term indicating a range covered by a base station in order for a wireless terminal to transmit and receive a wireless signal. However, since a base station and a cell are almost corresponding concepts, “Cell” may be appropriately read as “base station”.

It is believed that several effects can be obtained by introducing small cells. 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, as one of the technologies related to small cells, studies on dual connectivity have been started. In the two-way connection, wireless terminals connect to a plurality of base stations and communicate with each other at the same time, thereby transmitting or receiving different information simultaneously with each base station. In other words, according to the two-way connection, the wireless terminal can perform individual communication in parallel with each of the plurality of base stations. Alternatively, the wireless terminal can perform communication (in parallel or in parallel) using resources of a plurality of 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 TS36.413 V11.5.0 (2013-09) 3GPP TS36.423 V11.6.0 (2013-09) 3GPP R2-133292 (2013-10) 3GPP R2-133732 (TR36.842 V0.4.0) (2013-10)

As described above, in 3GPP, discussions have started about dual 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, there is no terminal management mechanism that is desirable for a wireless terminal to realize two-way connection with a plurality of cells in a conventional LTE system.

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, a disclosed wireless communication method is provided for a first wireless station in which a first base station can communicate in parallel with the first base station and the second base station. A first radio station identifier selected and assigned from the first radio station identifier set, and a second radio station identifier at least partially overlapping with the first radio station identifier set by the second base station for the second radio station At least one of the first base station and the second base station performs control so that the second radio station identifier selected and assigned from the set does not overlap, and the first radio station assigns the first radio station identifier to the first radio station identifier. To communicate with at least the first base station, and the second radio station communicates with the second base station using the second radio station identifier.

According to one aspect of the wireless communication method, the wireless communication system, the base station, and the wireless station disclosed in the present 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. 2A to 2C are diagrams each illustrating an example of an identifier space for C-RNTI in the LTE system. FIG. 3 is a diagram illustrating an example of a processing sequence in the wireless communication system according to the second embodiment. 4A to 4D are diagrams (part 1) illustrating an example of an identifier space for C-RNTI in the wireless communication system according to the second embodiment. 5A to 5C are diagrams (part 2) illustrating an example of a C-RNTI identifier space in the wireless communication system according to the second embodiment. 6A to 6C are diagrams (part 3) illustrating an example of an identifier space for C-RNTI in the wireless communication system according to the second embodiment. 7A to 7C are diagrams each illustrating an example of a C-RNTI identifier space in the wireless communication system according to the second modification of the second embodiment. 8A to 8C are diagrams each illustrating an example of a C-RNTI identifier space in the wireless communication system according to the third modification of the second embodiment. 9A to 9C are diagrams each illustrating an example of a C-RNTI identifier space in the wireless communication system according to the fourth modification of the second embodiment. FIG. 10 is a diagram illustrating an example of a processing sequence in the wireless communication system according to the third embodiment. FIG. 11 is a diagram illustrating an example of a processing sequence in the wireless communication system according to the first modification of the third embodiment. FIG. 12 is a diagram illustrating an example of a processing sequence in the wireless communication system according to the second modification of the third embodiment. FIG. 13 is a diagram illustrating an example of a processing sequence in the wireless communication system according to the fourth embodiment. FIG. 14 is a diagram illustrating an example of a processing sequence in the wireless communication system according to the first modification of the fourth embodiment. FIG. 15 is a diagram illustrating an example of a processing sequence in the wireless communication system according to the second modification of the fourth embodiment. FIG. 16 is a diagram illustrating an example of a processing sequence in a wireless communication system according to another embodiment (part 1). FIG. 17 is a diagram illustrating an example of a processing sequence in a wireless communication system according to another embodiment (part 2). FIG. 18 is a diagram illustrating an example of a network configuration of the wireless communication system according to each embodiment. FIG. 19 is a diagram illustrating an example of a functional configuration of a wireless terminal in each embodiment. FIG. 20 is a diagram illustrating an example of a functional configuration of the base station in each embodiment. FIG. 21 is a diagram illustrating an example of a hardware configuration of a wireless terminal in each embodiment. FIG. 22 is a diagram illustrating an example of a hardware configuration of a base station 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, there is no terminal management that is desirable for the wireless terminal 20 to realize two-way connection with a plurality of cells in the conventional LTE system. Therefore, it is examined whether the terminal management desirable for realizing the two-way connection is possible by using the technology already defined in the conventional LTE system.

As preparation for the examination, an outline of transmission / reception processing of downlink data 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, a wireless terminal is generally referred to as UE (User Equipment), and a base station (wireless base station) is referred to as eNB (evolved Node B). It should be noted that the wireless terminal in the present application can be generalized as a wireless station. The wireless station can include a wireless communication device capable of performing wireless communication with the base station.

When transmitting the downlink data, the base station 10 transmits the downlink data accompanied by DCI (Downlink Control Information) that is downlink control information. Here, the DCI includes various control information for the wireless terminal 20 to receive downlink data. Downlink data is transmitted via a physical downlink shared channel (PDSCH: “Physical” Downlink “Shared” CHannel), and DCI is transmitted via a physical downlink control channel (PDCCH: “Physical” Downlink “Control” CHannel).

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

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, as will be described later, a part of the 16-bit space cannot be used as C-RNTI), and the radio terminal 20 is a random number for synchronizing uplink with the base station 10. In the access procedure, a C-RNTI assignment is received from the base station 10. Each base station 10 (cell) 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 (cell), the radio terminal 20 receives a new C-RNTI assignment from the destination base station 10.

The DCI and downlink data reception processing by the wireless terminal 20 will be described. Since the radio terminal 20 does not know when the DCI addressed to itself is sent, it constantly monitors the DCI mapped to the control signal area of each downlink subframe. Then, the radio terminal 20 performs a CRC operation on the DCI on the DCI after demasking (unmasking) the CRC added to the DCI using its own C-RNTI. As a result, the radio terminal 20 can determine whether or not the DCI is addressed to itself (if the DCI is not addressed to itself, a CRC error occurs).

The DCI is scrambled by PCI (Physical Cell Identifier) which is an identifier of the base station 10 (cell) and transmitted from the base station 10. The wireless terminal 20 recognizes PCI in advance by PSS (Primary Synchronization Signal) and SSS (Secondary Synchronization Signal) which are synchronization signals of the base station 10, and descrambles (disscrambles) the received DCI. be able to.

When the wireless terminal 20 receives the DCI addressed to itself, the wireless terminal 20 downloads the downlink data addressed to itself mapped on the same subframe as the DCI based on various control information (subcarrier information, MCS, etc.) included in the DCI. Is demodulated and decoded. Thereby, the radio | wireless terminal 20 can receive the downlink data addressed to self.

In summary, the wireless terminal 20 receives the DCI addressed to itself from the base station 10 based on the C-RNTI assigned to itself. Based on the received DCI, it receives downlink data addressed to itself.

Talking back to the original, we will explain the wireless terminal management that is desirable to achieve a two-way connection. 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. Note that an operation mode in which two C-RNTIs are allocated to terminals connected in two ways is also assumed, and such a case will be described later.

Now, the first radio terminal 20a, which is a radio terminal 20 capable of two-way connection, is connected to the macro base station 10a (macro cell), and the first radio terminal 20a transmits and receives 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, it is assumed that the first radio terminal 20a is assigned # N1 as C-RNTI from the macro base station 10a.

Next, it is assumed that the first radio terminal 20a 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 first radio terminal 20a is connected in two ways to the macro base station 10a and the small base station 10b. For example, the first radio terminal 20a reports the reception quality from the small base station 10b to the macro base station 10a, and the macro base station 10a determines that the first radio terminal 20a is to be connected in two based on the reception quality. Then, the wireless terminal 20 is notified of the determination. Thereafter, the first radio terminal 20a 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 a C-RNTI already assigned to the first radio terminal 20a. This is because it is necessary for the small base station 10b to transmit downlink data to the first radio terminal 20a. 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.

Through the above procedure, two-way connection is realized in the first radio terminal 20a, and the first radio terminal 20a can receive downlink data from each of the macro base station 10a and the small base station 10b. This procedure is sufficient if the wireless terminal 20 connected to the small base station 10b is only the first wireless terminal 20a, but when the other wireless terminal 20 is also connected to the small base station 10b, There is room for such problems.

Now, it is assumed that when the first radio terminal 20a 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 first radio terminal 20a, and is a radio terminal 20 that cannot be connected in two ways as an example. 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. As a result, C-RNTI is established between the first radio terminal 20a that performs 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, it is assumed that the small base station 10b transmits downlink data to the second radio terminal 20b. The DCI associated with the downlink data is transmitted after being masked by # N1, which is the C-RNTI of the second radio terminal 20b. Therefore, the second radio terminal 20b monitoring the DCI masked with C-RNTI = # N1 transmitted from the small base station 10b can correctly receive the DCI and downlink data addressed to the second radio terminal 20b. .

However, the C-RNTI of the first radio terminal 20a is also # N1, and the first radio terminal 20a is also connected to the small base station 10b. Therefore, the first radio terminal 20a also monitors the DCI masked with C-RNTI = # N1 transmitted from the small base station 10b. As a result, the first radio terminal 20a also erroneously receives the DCI addressed to the second radio terminal 20b (and thus downlink data associated with the DCI). This is because the DCI addressed to the second radio terminal 20b is masked with C-RNTI = # N1, so that the DCI appears to itself as viewed from the first radio terminal 20a. Thus, there is a problem that unintended reception of DCI (and downlink data) occurs in the first radio terminal 20a due to duplication of C-RNTI.

By the way, in the above description, the erroneous reception that occurs in the first radio terminal 20a when the small base station 10b transmits the downlink data to the second radio terminal 20b has been described as an example. Even when downlink data is transmitted to 20a, the same erroneous reception may occur in the second wireless terminal 20b. On the other hand, when the macro base station 10a transmits downlink data to the first radio terminal 20a, 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 since the second radio terminal 20b is not connected to the macro base station 10a, the second radio terminal 20b transmits the C-RNTI transmitted from the macro base station 10a. This is because DCI masked with = # N1 is not monitored. Here, as described above, since the DCI transmitted from the macro base station 10a and the DCI transmitted from the small base station 10b are scrambled by different PCIs (cell identifiers), the second radio terminal 20b Note that the DCI transmitted from the base station 10 can be distinguished.

In the above description, the case where downlink data is transmitted / received in the LTE system has been described as an example. However, a similar problem may occur when uplink data is transmitted / received in the LTE system. This is because DCI accompanies not only downlink data but also uplink data transmitted / received via a physical uplink shared channel (PUSCH: “Physical” Uplink “Shared” CHannel). Incidentally, the DCI accompanying the uplink data corresponds to permission to transmit uplink data from the base station 10 to the radio terminal 20, and may be called UL grant.

Also, in the above description, the double reception problem based on C-RNTI duplication has been described, but 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 assigned between base stations 10 includes Semi-PersistentPersistScheduling 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 using the LTE system as an example, it should be noted that the above problems are not limited to the LTE system. 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. In order not to lose the generality, here, a case where a plurality of C-RNTIs are assigned is also included, and in this case, the assigned C-RNTIs are assigned so as not to overlap between wireless terminals. 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 problems such as erroneous reception associated with the two-way connection will be described in order.

[First embodiment]
In the first embodiment, the first base station 10 (for example, the macro base station 10a) communicates (for example, two-way connection) in parallel with the first base station 10 and the second base station 10 (for example, the small base station 10b). A first radio station identifier (for example, C-RNTI) that is selected and assigned to a first radio station 20a that can be selected from a first radio station identifier set (for example, a C-RNTI space in a 16-bit identifier space); The second base station 10 has a second radio station identifier set (for example, for C-RNTI in a 16-bit identifier space) that overlaps at least partly with the first radio station identifier set with respect to the second radio station 20b. At least one of the first base station 10 and the second base station 10 performs control so that a second radio station identifier (for example, C-RNTI) selected and allocated from the space does not overlap. The station 20a obtains the first wireless station identifier. There are to communicate at least the first base station 10, the second radio station 20b is communicating with the second base station 10 by using the second radio station identifier.

In the first embodiment and each of the following embodiments, the case where downlink data is mainly transmitted / received in the LTE system has been described as an example, but the same applies to the case where uplink data is transmitted / received in the LTE system. Note that is possible.

Further, in the first embodiment and each of the following embodiments, a case has been described where double reception based on C-RNTI duplication is solved, but 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. Examples of RNTI that should be allocated without overlapping between base stations 10 include Semi-Persistent Scheduling C-RNTI, Temporary C-RNTI, TPC-PUCCH-RNTI, and TPC-PUSCH-RNTI in addition to C-RNTI. In the first embodiment and each of the following embodiments, two of the macro base station 10a (macro cell) and the small base station 10b (small cell) in the LTE system are mainly used. Although the description is based on the original connection, it should be noted that the application range of the present invention is not limited to this and 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)”.

Furthermore, in the first embodiment and each of the following embodiments, the description is mainly 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, the first terminal identifier assigned to the first radio terminal 20 by the first base station 10 and the second terminal assigned to the second radio terminal 20 by the second base station 10. There is no duplicate identifier. As a result, it is possible to avoid problems such as erroneous reception associated with the two-way connection described above. As a result, it is possible to realize terminal management that is desirable for realizing two-way connection.

[Second Embodiment]
In the second embodiment, the first embodiment is applied to an LTE system. Specifically, in the second embodiment, a part of a space of approximately 16 bits that can be used as C-RNTI is reserved as a space for C-RNTI for wireless terminals 20 that can be connected in two ways. This solves the problems such as erroneous reception associated with the above-described two-way connection.

First, the premise of the second embodiment will be described. As described above, some wireless terminals 20 are capable of two-way connection. In the second embodiment, it is assumed that there is only one C-RNTI assigned to the radio terminal 20 even if the radio terminal 20 is connected in two ways. 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.

Next, as a preparation for explaining the basic concept of the second embodiment, possible values of C-RNTI in a general LTE system will be described. As described above, C-RNTI is a 16-bit terminal identifier used for data communication, but not all 16-bit space can be used as C-RNTI. In the first place, RNTI, which is a terminal identifier, includes, in addition to C-RNTI for data communication, RA-RNTI for random access (Random-Access-Radio-Network-Temporary-Identifier), Semi-Persistent-Scheduling-C-RNTI for semi-persistent scheduling, primary There are Temporary C-RNTI, which is a typical C-RNTI, TPC-PUCCH-RNTI for transmission power for the uplink control channel, and TPC-PUSCH-RNTI for the uplink data channel. (TPC-PUCCH-RNTI and TPC-PUSCH-RNTI may be collectively referred to as TPC-RNTI). It should be noted that RA-RNTI is basically used so as not to compete with other RNTI. In the following description, the term “(identifier) space” is used based on the fact that the terminal identifier (RNTI) is a bit string, but the more general term “(identifier) set” may be used. Absent.

Referring to FIG. 2A, an identifier space for RNTI in a general LTE system will be described. As shown in FIG. 2A, the entire 16-bit identifier space can be divided into four. Space 1 is a space for RA-RNTI. Space 2 is a space for C-RNTI, Semi-Persistent Scheduling C-RNTI, Temporary C-RNTI, and TPC-RNTI (TPC-PUCCH-RNTI, TPC-PUSCH-RNTI). Space 3 is a reserved space (reserved), and space 4 is a space for other RNTI.

In FIG. 2A, it is defined in the standard specification that the boundary between the space 2 and the space 3 and the boundary between the space 3 and the space 4 are fixed. Specifically, the space 2 is up to 65523, and the space 3 is up to 65532. On the other hand, the boundary between the space 1 and the space 2 is variable, and each base station 10 can be set individually. However, due to the specifications of the LTE system, space 1 is limited to a maximum of 60 in the case of time division duplex (TDD: “Time” Division “Duplex”). Note that space 1 is limited to a maximum of 10 in the case of frequency duplex (TDD: “Time” Division “Duplex”). In the present application, the present invention will be described based on the case of TDD, but it goes without saying that the present invention can be similarly applied to the case of FDD.

Examples of identifier space settings in a conventional LTE system are shown in FIGS. 2B to 2C. FIG. 2B shows a setting example in which the size of the space 1 is 10. In this case, the size of the space 2 is 65513. On the other hand, FIG. 2C shows a setting example in which the size of the space 1 is 60. In this case, the size of the space 2 is 65463. From these setting examples, it can be seen that the size of the space 2 that can be used as the C-RNTI may be slightly different for each base station 10, but generally overlaps between the base stations 10.

Next, the basic concept of the second embodiment will be described. In the second embodiment, a macro base station 10a reserves a C-RNTI space (hereinafter referred to as a binary connection identifier space for convenience) allocated to a wireless terminal 20 that can be connected in a binary manner. Then, the small base station 10b performs control so that the C-RNTI included in the binary connection identifier space reserved by the macro base station 10a is not assigned to the radio terminal 20 under its control. As a result, the C-RNTI allocated to the two-way connectable radio terminal 20 under the macro base station 10a and the C-RNTI of the radio terminal 20 under the small base station 10b do not overlap. It is possible to avoid problems such as erroneous reception associated with the original connection.

The above is the basic idea of the second embodiment, but it is desirable to add further arrangement when applying this to the LTE system. As described above, the identifier space for C-RNTI (space 2 in FIGS. 2A to 2C) depends on the identifier space for RA-RNTI (space 1 in FIGS. 2A to 2C), and The station 10 can individually set an identifier space for RA-RNTI. Therefore, when the macro base station 10a randomly selects the binary connection identifier space, the dual connection identifier space may hinder the individual setting of the RA-RNTI identifier space by the small base station 10b. is there. Such a situation is considered undesirable from the viewpoint of compatibility with existing standard specifications in the LTE system.

Therefore, in the second embodiment, first, each base station 10 (macro base station 10a and small base station 10b) individually sets an RA-RNTI identifier space, and then the small base station 10b Notify the RA-RNTI identifier space that you set. The macro base station 10a selects and sets a two-way identifier space from an identifier space that is not used as an RA-RNTI identifier space by any of the base stations 10 (the macro base station 10a and the small base station 10b). . By performing such a procedure (hereinafter referred to as an identifier space setting procedure for convenience), the individual setting of the RA-RNTI identifier space by the small base station 10b is hindered by the two-way connection identifier space. Can be avoided.

The identifier space setting procedure described above can be performed when each base station 10 (macro base station 10a, small base station 10b) is installed (including when it is added), initialized, or reset. Further, it may be performed appropriately at other timings. However, basically, it is sufficient to perform the identifier space setting procedure only at the time of installation or initialization of each base station 10 and at the time of resetting, and at least the base station 10 performs each wireless terminal 20. Note that this is not a necessary procedure. Therefore, the increase in the amount of signaling or the processing load due to the introduction of the identifier space setting procedure is very limited, and it is considered that the procedure has a low barrier to introduction. In particular, when the backhaul network between the base stations 10 is non-ideal with a relatively large delay, it is needless to say that a smaller amount of signaling is desirable.

FIG. 3 shows an example of the processing sequence of the identifier space setting procedure according to the second embodiment. FIG. 3 shows an example in which one macro base station 10a and one small base station 10b (first small base station 10b1) are first installed, and then another small base station 10b (second small base station 10b2). Shows a processing sequence in the case where is additionally installed and resetting is further performed.

3, first, the macro base station 10a and the first small base station 10b1 individually set RA-RNTI identifier spaces. Here, as an example, as shown in FIG. 4A, the macro base station 10a assigns 1 to 20 of the 16-bit space as the RA-RNTI identifier space (the diagrams showing the identifier space thereafter). In FIG. 2, only space 1 and space 2 in FIG. 2 are shown, and space 3 and space 4 are omitted). Further, as shown in FIG. 4B, the first small base station 10b1 is assumed to have assigned 1 to 30 of the 16-bit space as the RA-RNTI identifier space. It should be noted that the macro base station 10a does not set the binary connection identifier space at this stage.

In S102 of FIG. 3, the macro base station 10a transmits an RNTI identifier space setting request (SETUP) REQUEST) to the first small base station 10b1. The SETUP REQUEST in S102 can include the RA-RNTI identifier space set by the macro base station 10a in S101, and is information indicating the entire RNTI identifier space including the RA-RNTI identifier space (hereinafter referred to as identifier space). It may also be referred to as a table, which may be referred to as an RNTI table or the like. SETUP REQUEST in S102 can be realized by a control message of the Xn protocol that is an interface between the base stations 10. It should be noted that Xn is a name for convenience and the name related to the interface name for realizing the two-way connection between the base stations is not limited to Xn without losing generality.

Next, in S103, the first small base station 10b1 transmits an RNTI identifier space setup response (SETUP RESPONSE) to the macro base station 10a in response to SETUP REQUEST in S102. Here, SETUP と す る RESPONSE in S103 is assumed to include the RA-RNTI identifier space set by the first small base station 10a in S101. Further, the SETUP-RESPONSE here may include an identifier space table including the RA-RNTI identifier space. Thereby, the macro base station 10a recognizes that the first small base station 10b1 has assigned 1 to 30 as the identifier space for RA-RNTI.

In S104 of FIG. 3, the macro base station 10a sets a two-way identifier space for the first small base station 10b1. At this time, the macro base station 10a sets a binary connection identifier space so as not to overlap with the RA-RNTI identifier space of the first small base station 10b1 recognized in S103. As described above, since the first small base station 10b1 assigns 1 to 30 as the RA-RNTI identifier space, the macro base station 10a controls not to assign 1 to 30 as the two-way connection identifier space. Since the macro base station 10a has already assigned 1 to 20 as the RA-RNTI identifier space, 21 to 30 should not be assigned as the binary connection identifier space at this stage. Here, as an example, as shown in FIG. 4C, it is assumed that the macro base station 10a allocates 31 to 80 out of the 16-bit space as a two-way connection identifier space for the first small base station 10b1. As a result, as shown in FIG. 4C, 21 to 30 and 81 to 65523 in the identifier space of the macro base station 10a can be used for applications other than C-RNTI for wireless terminals 20 that can be connected in two ways (for example, two-way connection This is a space (hereinafter referred to as a free space for convenience) used for an impossible wireless terminal 20 (C-RNTI, TPC-RNTI, etc.).

In S105 of FIG. 3, the macro base station 10a transmits a notification (eNB 通知 CONFIG UPDATE) indicating that the macro base station has updated the RNTI identifier space to the first small base station 10b1. Here, the eNB | CONFIG | UPDATE of S105 shall include the identifier space for two-way connection which the macro base station 10a set in S104. Also, the eNB CONFIG UPDATE here may include an identifier space table including the binary connection identifier space. Thereby, the first small base station 10b1 recognizes that the macro base station 10a has assigned 31 to 80 as a two-way identifier space for the first small base station 10b1. The notification in S105 can be realized by a control message of the Xn protocol.

After S105 in FIG. 3, the first small base station 10b1 does not use 31 to 80 allocated as the identifier space for two-way connection by the macro base station 10a (hereinafter, this space is referred to as an unused space for convenience). ). In S106, the first small base station 10b1 transmits a notification (eNB CONFIG UPDATE ACK) indicating this to the macro base station 10a. The notification in S105 can be realized by a control message of the Xn protocol. The free space of the first small base station 10b1 is 81 to 65523 as shown in FIG. 4D.

After S106 in FIG. 3, the macro base station 10a uses 31 to 80 as a binary connection identifier space for the first small base station 10b1, as shown in FIG. 4C. In addition, 21 to 30 and 81 to 65523 are used as free spaces, and 1 to 20 are used as identifier spaces for RA-RNTI.

Due to the identifier space setting procedure in S101 to S106 (when the base station 10 is installed), the binary connection identifier space (31 to 80) for the first small base station 10b1 in the macro base station 10a is not used in the first small base station 10b1. It becomes space. For this reason, the C-RNTI of the radio terminal 20 that can be dually connected to the macro base station 10a and the first small base station 10b1 overlaps with the C-RNTI of the conventional radio terminal 20 that is connected to the first small base station 10b1. It will not be possible. As a result, it is possible to avoid problems such as erroneous reception associated with the two-way connection described above.

Consider the case where the second small base station 10b2 is added based on FIG.

In S107 of FIG. 3, the second small base station 10b2 individually sets an RA-RNTI identifier space. Here, as an example, as shown in FIG. 5A, it is assumed that the second small base station 10b2 assigns 1 to 10 out of 16-bit spaces as RA-RNTI identifier spaces.

In S108 of FIG. 3, the second small base station 10b2 transmits SETUP に REQUEST to the macro base station 10a. SETUP REQUEST in S108 includes the RA-RNTI identifier space set by the second small base station 10b2 in S107. Further, SETUP REQUEST here may include an identifier space table including the RA-RNTI identifier space. Thereby, the macro base station 10a recognizes that the second small base station 10b2 has assigned 1 to 10 as the RA-RNTI identifier space. The notification in S107 can be realized by a control message of the Xn protocol.

In S109 of FIG. 3, the macro base station 10a sets a two-way identifier space for the second small base station 10b2. At this time, the macro base station 10a sets a two-way identifier space so as not to overlap with the RA-RNTI identifier space of the second small base station 10b2 recognized in S108. As described above, since the second small base station 10b2 assigns 1 to 10 as the RA-RNTI identifier space, the macro base station 10a controls not to assign 1 to 10 as the two-way connection identifier space. Since the macro base station 10a has already assigned 1 to 10 as RA-RNTI identifier spaces, these are inevitably assigned here as binary connection identifier spaces.

Several methods are conceivable for setting the two-way connection identifier space. Here, as an example, the two-way connection identifier space set by the macro base station 10a for each small base station 10b is not duplicated. (It is also possible to overlap as described later). Therefore, the macro base station 10a sets the binary connection identifier space for the second small base station 10b2 so as not to overlap with the dual connection identifier spaces 31 to 80 for the first small base station 10b1.

Here, as an example, as shown in FIG. 5B, the macro base station 10a allocates 21 to 30 and 81 to 100 of the 16-bit space as the two-way connection identifier space for the second small base station 10b2. To do. As a result, the free space of the macro base station 10a becomes 101 to 675523 as shown in FIG. 5B. Note that the identifier spaces 21 to 30 could not be set as the two-way identifier space because they were already assigned as the RA-RNTI identifier space in the first small base station 10b1, but in the second small base station 10b2, Note that since it is not assigned as an RA-RNTI identifier space, it may be set as a binary connection identifier space.

In S110 of FIG. 3, the macro base station 10a transmits SETUP１０RESPONSE to the second small base station 10b2. At this time, the macro base station 10a may transmit SETUP RESPONSE also to the first small base station 10b1. Here, SETUP と す る RESPONSE in S110 is assumed to include the two-way connection identifier space set by the macro base station 10a in S109. Further, the SETUP_RESPONSE here may include an identifier space table including the binary connection identifier space. As a result, the second small base station 10b2 recognizes that the macro base station 10a has assigned 21 to 30 and 81 to 100 as the two-way connection identifier space for the second small base station 10b2. The notification in S110 can be realized by a control message of the Xn protocol.

After S110 in FIG. 3, the second small base station 10b2 sets 21 to 30 and 81 to 100 allocated as the identifier space for two-way connection by the macro base station 10a as unused spaces, as shown in FIG. 5C. In S111, the second small base station 10b2 transmits a notification (eNB CONFIG UPDATE) indicating this to the macro base station 10a. At this time, the first small base station 10b1 may also transmit eNB CONFIG UPDATE to the macro base station 10a. The notification in S111 can be realized by a control message of the Xn protocol.

The free space of the second small base station 10b2 is 11 to 20, 31 to 80, and 101 to 65523, as shown in FIG. 5C. Here, it should be noted that the identifier spaces 31 to 80 are unused spaces for the first small base station 10b1, but are free spaces for the second small base station 10b2.

3, in S112 of FIG. 3, the macro base station 10a transmits a response signal (eNB 通知 CONFIG UPDATE ACK) to the notification of S111 to the second small base station 10b2. At this time, the macro base station 10a may also transmit eNB CONFIG UPDATE ACK to the first small base station 10b1. The response signal of S112 can be realized by a control message of the Xn protocol.

After S112 in FIG. 3, the macro base station 10a uses 31 to 80 as the binary connection identifier space for the first small base station 10b1, and the binary for the second small base station 10b2, as shown in FIG. 5B. Use 21-30 and 81-100 as identifier space for connection. Also, 101 to 65523 is used as a free space, and 1 to 20 is used as an RA-RNTI identifier space.

According to the identifier space setting procedure of S107 to S112 (when the base station 10 is added), the binary connection identifier space (21 to 30 and 81 to 100) for the second small base station 10b2 in the macro base station 10a is changed to the second small base station. It becomes an unused space in 10b2. Therefore, the C-RNTI of the radio terminal 20 that can be dually connected to the macro base station 10a and the second small base station 10b2 overlaps with the C-RNTI of the conventional radio terminal 20 that is connected to the second small base station 10b2. It will not be possible. As a result, it is possible to avoid problems such as erroneous reception associated with the two-way connection described above.

Suppose that the identifier space is reset again based on FIG. Here, an example in which resetting is performed starting from the second small base station 10b2 will be described, but it is needless to say that this is only an example.

In S113 of FIG. 3, the second small base station 10b2 individually resets the RA-RNTI identifier space. Here, as an example, as shown in FIG. 6A, the second small base station 10b2 newly adds 11 to 40 as the RA-RNTI identifier space, and as a result, reconfigures 1 to 40 as the RA-RNTI identifier space. It is assumed that it has been set.

In S114 of FIG. 3, the second small base station 10b2 notifies SETUP を REQUEST to the macro base station 10a. Here, SETUP REQUEST in S114 is assumed to include the RA-RNTI identifier space reset by the second small base station 10b2 in S113. Further, SETUP REQUEST here may include an identifier space table including the RA-RNTI identifier space. Thereby, the macro base station 10a recognizes that the second small base station 10b2 has reset 1 to 40 as the RA-RNTI identifier space. The notification in S114 can be realized by a control message of the Xn protocol.

3, in S115 of FIG. 3, the macro base station 10a resets the two-way identifier space for the second small base station 10b2. At this time, the macro base station 10a resets the binary connection identifier space so as not to overlap with the RA-RNTI identifier space of the second small base station 10b2 recognized in S114. As described above, since the second small base station 10b2 resets 1 to 40 as the RA-RNTI identifier space, the macro base station 10a controls not to assign 1 to 40 as the two-way connection identifier space.

Here, as an example, as shown in FIG. 6B, the macro base station 10a resets 81 to 110 out of the 16-bit space as a binary connection identifier space for the second small base station 10b2. As a result, the free space of the macro base station 10a becomes 21 to 30 and 111 to 675523 as shown in FIG. 6B. Note that the identifier spaces 21 to 30 were not assigned as the RA-RNTI identifier space of the second small base station 10b2 in S109, and thus could be set as the binary connection identifier space. It should be noted that the base station 10b2 has been reconfigured as the RA-RNTI identifier space, and thus cannot be set as a binary connection identifier space (this space can be used as a free space).

3 may be performed based on the same concept as S110 to S112 in FIG. 3, and thus a detailed description is omitted. The unused space of the second small base station 10b2 is 81 to 100 as shown in FIG. 6C. The free space of the third small base station 10b is 41 to 80 and 111 to 65523, as shown in FIG. 6C.

Due to the identifier space setting procedure (at the time of resetting) of S113 to S118, the binary connection identifier space (81 to 110) for the second small base station 10b2 in the macro base station 10a becomes the unused space in the second small base station 10b2. Become. Therefore, the C-RNTI of the radio terminal 20 that can be dually connected to the macro base station 10a and the second small base station 10b2 overlaps with the C-RNTI of the conventional radio terminal 20 that is connected to the second small base station 10b2. It will not be possible. As a result, it is possible to avoid problems such as erroneous reception associated with the two-way connection described above.

As described above, according to the identifier space setting procedure according to the second embodiment shown in FIG. 3, the small base station 10b (first small base station 10b1) installed at the same time as the macro base station 10a. However, also for the small base station 10b (second small base station 10b2) added thereafter, it is possible to avoid the above-described problems such as erroneous reception due to the two-way connection.

Hereinafter, various modifications of the above-described second embodiment will be described.

In the first modification of the second embodiment, the macro base station 10a freely sets the RNTI identifier space in each small base station 10b. In the second embodiment described above, each small base station 10b can individually set the RA-RNTI identifier space. On the other hand, in this modification, the macro base station 10a also sets the RA-RNTI identifier space in each small base station 10b.

According to the first modification of the second embodiment, in the processing sequence of the second embodiment shown in FIG. 3, for example, in S101, the first small base station 10b1 does not set its own RA-RNTI identifier space. . In 102 SETUP REQUEST and S103 SETUP RESPONSE, the identifier space table may be exchanged, or operation is possible even if omitted. Then, in S104, the macro base station 10a sets not only the binary connection identifier space for the first small base station 10b1, but also the RA-RNTI identifier space for the first small base station 10b1.

Further, in S105, the macro base station 10a transmits an eNB CONFIG UPDATE including the RA-RNTI identifier space and the binary connection identifier space to the first small base station 10b1. Then, in S106, the first small base station 10b1 may transmit a response signal eNB | CONFIG | UPDATE | ACK with respect to the signal of S105 to the macro base station 10a.

According to the first modification of the second embodiment, the signal amount between the base stations 10 can be reduced as compared with the second embodiment described above. In addition, the setting time of the identifier space for RNTI can be expected to be shortened.

In the second modification of the second embodiment, the macro base station 10a sets the binary connection identifier space in advance from the space that the small base station 10b cannot use as the RA-RNTI identifier space. In the second embodiment described above, the macro base station 10a sets the binary connection identifier space for each small base station 10b so as not to overlap with the RA-RNTI identifier space notified from each small base station 10b. It was selected and set. However, as described above, due to the specifications of the LTE system, the RA-RNTI identifier space individually set in each base station 10 is 1 to 60 at the maximum. Therefore, if the macro base station 10a allocates a binary connection identifier space for each small base station 10b from 61 to 65523 (a space that cannot be used as an RA-RNTI identifier space), the binary connection identifier In principle, the space does not overlap with the RA-RNTI identifier space.

7A to 7C show an example of an identifier space according to the second modification example of the second embodiment. 7A, 7B, and 7C show examples of the identifier space of the macro base station 10a, the identifier space of the first small base station 10b1, and the identifier space of the second small base station 10b2, respectively. In FIG. 7A, for example, the macro base station 10a sets the identifier spaces 61 to 110 as the binary connection identifier space for the first small base station 10b1, and sets the identifier spaces 111 to 140 to the second small base station 10b2. Set as an identifier space. By doing so, as illustrated in FIGS. 7B and 7C, no matter how each small base station 10b allocates the RA-RNTI identifier space, it does not overlap with the two-way identifier space.

According to the second modification example of the second embodiment, the signal amount between the base stations 10 can be reduced as in the first modification example described above. In addition, the setting time of the identifier space for RNTI can be expected to be shortened.

The third modification of the second embodiment relates to the setting of a binary connection identifier space. In the second embodiment described above, as described in S109 of FIG. 3, the two-way connection identifier spaces set for each small base station 10b by the macro base station 10a are not duplicated. However, the two-way identifier space set by the macro base station 10a for each small base station 10b may be overlapped. Further, these two methods may be selectively used depending on the situation.

8A to 8C show an example of an identifier space according to the third modification example of the second embodiment. 8A, 8B, and 8C show examples of the identifier space of the macro base station 10a, the identifier space of the first small base station 10b1, and the identifier space of the second small base station 10b2, respectively.

8A to 8C, for example, identifier spaces 31 to 50 are two-way identifier spaces for the first small base station 10b1 and the second small base station 10b2 in the macro base station 10a. That is, there is an overlap in the two-way identifier space set by the macro base station 10a for the first small base station 10b1 and the second small base station 10b2. 8A to 8C, as an example, an individual binary connection identifier space (51 to 80) for the first base station 10 and an individual dual connection identifier space (21 to 30) for the second base station 10. ) Is also set. However, the separate binary connection identifier space for each small base station 10b may not be set. In this case, the binary connection identifier spaces set by the macro base station 10a for the first small base station 10b1 and the second small base station 10b2 match (completely overlap).

In the fourth modification of the second embodiment, the small base station 10b also has a two-way identifier space. In the second embodiment described above, it is assumed that the C-RNTI can be assigned to the radio terminal 20 that can be connected in two ways only to the macro base station 10a, and the small base station 10b is not assigned. . Therefore, only the macro base station 10a has a binary connection identifier space and does not have a small base station 10b. On the other hand, in this modification, it is assumed that the small base station 10b can also allocate C-RNTI to the radio terminal 20 that can be connected in two ways. Therefore, the small base station 10b also has a binary connection identifier space.

FIGS. 9A to 9C show an example of an identifier space according to the fourth modification example of the second embodiment. 9A, 9B, and 9C show examples of the identifier space of the macro base station 10a, the identifier space of the first small base station 10b1, and the identifier space of the second small base station 10b2, respectively. In FIG. 9B, for example, the first small base station 10b1 sets the identifier spaces 101 to 120 as the binary connection identifier space for the macro base station 10a. In FIG. 9C, for example, the second small base station 10b2 has the identifier spaces 121 to 140. Is set as a binary connection identifier space for the macro base station 10a. In FIG. 9A, for example, the macro base station 10a sets the identifier spaces 101 to 140 as unused spaces. As a result, the small base station 10b can also assign C-RNTI to the wireless terminal 20 that can be connected in two ways, and avoids the macro base station 10a from assigning the C-RNTI to another wireless terminal 20. be able to.

Hereinafter, a design variation in the second embodiment will be described.

In the second embodiment described above, the identifier space table itself is transmitted in some of the notifications between the base stations 10. Specifically, for example, the identifier space table is transmitted in S102 to S103, S105 to S106, S108, S110, S114, and S116 in FIG. However, in these notifications, instead of exchanging the identifier space table (the entire setting of the RNTI identifier space) itself, it is also possible to notify only information related to the space set (changed) immediately before in the RNTI identifier space. It doesn't matter. In other words, in these notifications, only the difference information at the time of setting (changing) in the RNTI identifier space can be transmitted. Specifically, for example, in S102 of FIG. 3, the first small base station 10b1 can notify the macro base station 10a of the RA-RNTI identifier space. Further, for example, in S104, the macro base station 10a can notify the first small base station 10b1 of the binary connection identifier space for the first small base station 10b1. The same applies to other notices. By doing so, it is possible to reduce the signal amount between the base stations 10 as compared with the second embodiment described above. In addition, the setting time of the identifier space for RNTI can be expected to be shortened.

In the second embodiment described above, the starting point of the cooperation between the base stations 10 in the identifier space setting procedure is the macro base station 10a when the base station is installed, and the small base station 10b when the base station is added. At the time of resetting, the base station 10 is reset. Specifically, for example, when the base station is installed, the macro base station 10a notifies the first small base station 10b1 in S102 of FIG. Yes. However, at this time, the first small base station 10b1 may be a starting point for cooperation between the base stations 10 in the identifier space setting procedure. Any base station 10 may be a starting point for cooperation between base stations 10 in the identifier space setting procedure when adding or changing base stations.

In the second embodiment described above, the first small base station 10b1 spontaneously sets the RA-RNTI identifier space in S101 of FIG. However, the first small base station 10b1 may set the RA-RNTI identifier space in response to the reception of SETUP REQUEST in S102 of FIG. 3 (between S102 and S103 of FIG. 3).

The exchange of the identifier space table as in the present application is preferably performed at the time of setting the Xn interface, but can also be performed at the time of setting the X2 interface. The procedure is disclosed in TS36.423. It is also possible to exchange the identifier space table as in the present application when setting the S1 interface. The procedure is disclosed in TS36.413.

According to the second embodiment described above and various modifications thereof, the macro base station 10a reserves the binary connection identifier space, and the small base station 10b communicates with the radio terminal 20 under its control to the macro base station. Control is performed so that C-RNTI included in the binary connection identifier space reserved by 10a is not allocated. As a result, the C-RNTI allocated to the two-way connectable radio terminal 20 under the macro base station 10a and the C-RNTI of the radio terminal 20 under the small base station 10b do not overlap. It is possible to avoid problems such as erroneous reception associated with the original connection. As a result, it is possible to realize terminal management that is desirable for realizing two-way connection.

[Third embodiment]
In the third embodiment, the first embodiment is applied to an LTE system. Specifically, in the third embodiment, the base station 10 notifies the other base station 10 of the C-RNTI assigned to the wireless terminal 20 that can be connected in two ways, thereby achieving the above-described two-way connection. It solves problems such as erroneous reception.

First, the premise of the third embodiment will be described. In the third embodiment, as in the second embodiment, it is assumed that even if the wireless terminal 20 is connected in two ways, the C-RNTI assigned to the wireless terminal 20 is one. 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.

FIG. 10 shows an example of a processing sequence in the wireless communication system according to the third embodiment. Assume that a wireless terminal 20 that is not connected to any base station 10 is located in a cell formed by the macro base station 10a. Here, it is assumed that the wireless terminal 20 is a wireless terminal 20 capable of two-way connection.

The radio terminal 20 first receives a synchronization signal and a broadcast signal (both not shown) from the macro base station 10a to obtain necessary information. In S201 of FIG. 10, the wireless terminal 20 transmits a known signal called a random access preamble (random (access (RA) preamble) to the macro base station 10a. Here, since the random access preamble transmitted in S201 is randomly selected by the radio terminal 20, there is a possibility of collision with another radio terminal 20, but here, it is assumed that no collision has occurred.

On the other hand, in S202, the macro base station 10a selects a C-RNTI assigned to the wireless terminal 20 that can be connected in two ways. At this time, the macro base station 10a may assign an arbitrary value from the entire identifier space that can be used as the C-RNTI to the wireless terminal 20 that can be connected in two ways. In other words, at this time, the macro base station 10a selects an arbitrary value from the space 2 (identifier space that can be used as C-RNTI) in the identifier space for RNTI illustrated in FIGS. It can be assigned to the connectable wireless terminal 20. Here, as an example, it is assumed that # N1 is assigned as the C-RNTI for the two-way connectable wireless terminal 20.

Note that in the second embodiment, this point is different from the first embodiment. The macro base station 10a in the first embodiment described above is a part of the identifier space that can be used as the C-RNTI for the wireless terminal 20 that can be connected in two ways, from the two-way connected identifier space that has been reserved in advance. Assign a value. Therefore, it can be said that the fluidity of C-RNTI allocation to the two-way connectable wireless terminal 20 is higher in the second embodiment than in the first embodiment.

10, the macro base station 10 a transmits a random access response (random access (RA) response), which is a response signal to the random access preamble, to the wireless terminal 20. At this time, the macro base station 10a stores the C-RNTI (# N1) assigned to the radio terminal 20 as a temporary C-RNTI as Temporary-C-RNTI and notifies it. Thereby, the wireless terminal 20 can know Temporary C-RNTI assigned to itself. A series of processes in S201 to S203 is called a random access procedure. In the random access procedure, synchronization processing including uplink timing adjustment, transmission power adjustment, and the like is also performed, but the description is omitted because it is not directly related to the present application.

In step S203, the wireless terminal 20 receives the random access response including the Temporary C-RNTI, and can receive the DCI via the PDCCH using the Temporary C-RNTI (# N1). Further, based on the received DCI, an RRC (Radio Resource Control) signal can be received via the PDSCH and can be transmitted via the PUSCH. Here, the RRC signal is an upper layer control signal for performing various managements on radio resources. At this stage, the wireless terminal 20 is still unable to transmit / receive data accompanied by DCI.

In S204 of FIG. 10, the wireless terminal 20 transmits an RRC Connection Request message that is an RRC signal to the macro base station 10a via the PUSCH. On the other hand, in S205, the macro base station 10a transmits an RRC Connection Setup message that is an RRC signal to the radio terminal 20 via the PDSCH. When the wireless terminal 20 receives the RRC Connection Setup message, Temporary で C-RNTI # N1 received by the random access response in S203 is promoted to C-RNTI. As a result, the wireless terminal 20 recognizes that the C-RNTI assigned to itself is # 1. Subsequent radio terminals 20 receive DCI via the PDCCH using the C-RNTI (# N1).

Further, in S206, the radio terminal 20 transmits an RRC connection setup message that is an RRC signal to the macro base station 10a via the PUSCH. As a result, the wireless terminal 20 completes the connection process and enters a connection state with respect to the base station 10. In the LTE system, this state is called an RRC-Connected state.

When the radio terminal 20 enters the RRC-Connected state, it becomes possible to receive the downlink data accompanied by the DCI via the PDSCH and to transmit the uplink data via the PUSCH. After S206, the radio terminal 20 can receive DCI using # N1 as C-RNTI with the macro base station 10a, and can receive downlink data associated with the DCI and transmit uplink data.

Next, in S207, the wireless terminal 20 transmits a measurement report (measurement report) to the macro base station 10a. The measurement report is a message signal in which the radio terminal 20 reports a measurement result based on a reference signal (reference signal) transmitted from the macro base station 10a and each neighboring base station 10 to the macro base station 10a. Here, each peripheral base station 10 to be measured includes not only the other macro base station 10a around the macro base station 10a but also one or more small base stations 10b under the control of the macro base station 10a. In general, the measurement report is used to select a base station 10 (target base station 10) that is a handover destination at the time of handover. Further, the measurement report includes a periodic report and an aperiodic report performed in response to a predetermined event, but the measurement report in S207 may be any one.

Next, it is assumed that the macro base station 10a determines that the wireless terminal 20 connected to the macro base station 10a is further connected to the small base station 10b based on the measurement report received in S207. That is, it is assumed that the macro base station 10 a has determined the small base station 10 b that is the connection destination of the two-way connection in the wireless terminal 20. For example, when measurement results for a plurality of small base stations 10b are reported from the radio terminal 20 in the measurement report, the macro base station 10a selects the small base station 10b that has the best measurement results and satisfies a predetermined standard, and the macro base station 10a It can be determined as a connection destination of the two-way connection in the terminal 20.

At this time, in S208 of FIG. 10, the macro base station 10a transmits a DC (Dual Connectivity) Request, which is a signal indicating that, to the small base station 10b that is the connection destination in the two-way connection of the wireless terminal 20. . DC Request is a message signal corresponding to a request for two-way connection from the macro base station 10a to the small base station 10b. Here, the macro base station 10a stores the C-RNTI (# N1) assigned to the radio terminal 20 in S202 in the DC Request and notifies the small base station 10b. As a result, the small base station 10b can recognize the C-RNTI of the wireless terminal 20 to which the small base station 10b is a connection destination for two-way connection. The DC Request can be realized by a control message of the Xn protocol that is an interface between the base stations 10.

Next, in S209 of FIG. 10, the small base station 10b changes (updates) the identifier space for RNTI so that the C-RNTI notified from the macro base station 10a in S208 is not assigned to the subordinate radio terminal 20. )I do. More specifically, the small base station 10b has received a notification in S208 from an identifier space (space 2 in the identifier space illustrated in FIGS. 2A to 2C) that can be used as a C-RNTI by itself. # N1 which is C-RNTI is excluded.

By doing so, the small base station 10b does not assign # N1 as C-RNTI to the wireless terminal 20 connected to the small base station 10b thereafter. That is, the small base station 10b is controlled not to use the C-RNTI already assigned to the radio terminal 20 to which the macro base station 10a performs the two-way connection in the subsequent C-RNTI assignment. As a result, the C-RNTI allocated to the two-way connectable radio terminal 20 under the macro base station 10a and the C-RNTI of the radio terminal 20 under the small base station 10b do not overlap. It is possible to avoid problems such as erroneous reception associated with the original connection.

In S210 of FIG. 10, the small base station 10b transmits a DC request ACK to the macro base station 10a. DC Request ACK corresponds to a response signal to DC Request in S208. DC Request ACK can be realized by a control message of Xn protocol.

Next, in S211, the macro base station 10a transmits an RRC Connection Re-configuration message that is an RRC signal to the radio terminal 20 via the PDSCH. The RRC Connection Re-configuration message is a control signal used in various scenes for resetting the wireless connection in the wireless terminal 20, but is used here to instruct the wireless terminal 20 to make a two-way connection to the small base station 10b. It is done. More specifically, in the RRC Connection Re-configuration message of S211, the wireless terminal 20 is instructed to add a connection to the small base station 10b and start the connection (activation). . More precisely, a cell to be used at the time of adding a small base station is added, and at the same time, communication can be immediately performed in the cell.

In S212, the wireless terminal 20 transmits an RRC Connection Re-configuration Complete message that is an RRC signal to the macro base station 10a via the PUSCH. The RRC Connection Re-configuration Complete message corresponds to a response signal to the RRC Connection Re-configuration message of S211.

Next, in S213 in FIG. 10, the small base station 10b transmits the PDCCH order to the wireless terminal 20. PDCCH order is a type of MAC control element, and is a signal that requests the wireless terminal 20 to transmit a random access preamble. In the small base station 10b, a random access preamble is designated in the PDCCH order.

In S214, the wireless terminal 20 transmits the random access preamble specified by the PDCCH order in S213 to the small base station 10b. On the other hand, the terminal small base station 10b transmits a random access response to the radio terminal 20 in response to the random access preamble of S214 in S215. In S214, since the random access preamble designated by the small base station 10b is used, unlike in S201, the other radio terminal 20 and the random access preamble do not collide (compete). A series of processing in S213 to S215 is also a random access procedure, but is called a non-collision type (non-contention type) random access procedure because the random access preambles do not collide. On the other hand, S201 to S203 are referred to as collision type (contention type) random access procedures.

As a result, the wireless terminal 20 enters a two-way connection state. That is, after S215, the radio terminal 20 can receive DCI using # N1 as C-RNTI and receive downlink data associated with DCI and transmit uplink data even with the small base station 10b. . At this time, since the connection between the radio terminal 20 and the macro base station 10a established in S206 is also maintained, it should be noted that the radio terminal 20 realizes a two-way connection.

By the way, unlike S203, the random access response transmitted by the small base station 10b in S215 does not need to include C-RNTI. This is because the wireless terminal 20 can also receive the DCI transmitted from the small base station 10b based on # N1, which is the C-RNTI already assigned from the macro base station 10a. In other words, the radio terminal 20 in the second embodiment can use one C-RNTI by switching to a plurality of base stations 10 (for example, the macro base station 10a and the small base station 10b).

Further, unlike S204 to S206, the wireless terminal 20 does not need to transmit / receive the RRC signal after the random access response of S215. This is because there is only one RRC for the radio terminal 20 in the standard specification of the LTE system.

As described above, according to the processing sequence of the wireless communication system according to the third embodiment shown in FIG. 10, the C-RNTI assigned to the wireless terminal 20 to which the macro base station 10a can perform two-way connection is assigned. The small base station 10b is notified. As a result, the C-RNTI allocated to the two-way connectable radio terminal 20 under the macro base station 10a and the C-RNTI of the radio terminal 20 under the small base station 10b do not overlap. It is possible to avoid problems such as erroneous reception associated with the original connection.

In FIG. 10, the macro base station 10a assigns # N1 as the C-RNTI to the two-way connectable radio terminal 20, but # N1 is not permanently assigned to the radio terminal 20 and has a predetermined value. In case it is released. For example, when the power of the wireless terminal 20 is turned off or when the wireless terminal 20 moves out of the range of the macro base station 10a, # N1 that is the C-RNTI assigned to the wireless terminal 20 is released. In this case, it goes without saying that # N1 can be assigned as C-RNTI to the radio terminal 20 to which the macro base station 10a is newly connected.

Furthermore, when # N1 which is C-RNTI is released in the macro base station 10a, the macro base station 10a preferably transmits a signal indicating that # N1 has been released to the small base station 10b. Such a signal may be transmitted to the small base station 10b every time one C-RNTI is released in the macro base station 10a, or collectively every time a predetermined interval or a predetermined number of C-RNTIs are released. It may be transmitted to the small base station 10b.

As a result, the small base station 10b changes (updates) the identifier space so that # N1 once removed from the identifier space that can be used as the C-RNTI is returned to the identifier space that can be used as the C-RNTI. Can do. That is, the small base station 10b performs control so that # N1 is not used as C-RNTI, but the control is released and # N1 can be used again as C-RNTI. As a result, the C-RNTI once eliminated in the small base station 10b is permanently eliminated, and the situation where the identifier space that can be used as the C-RNTI is insufficient can be avoided.

Hereinafter, various modifications of the above-described third embodiment will be described. These can be applied alone to the third embodiment, or a plurality of these may be applied to the third embodiment.

The first modification in the third embodiment relates to a procedure for realizing a two-way connection. In the processing sequence of the third embodiment shown in FIG. 10, two-way connection is realized by a procedure similar to handover. On the other hand, the 1st modification in 3rd Embodiment implement | achieves two-way connection by the procedure similar to a carrier aggregation (carrier-aggregation).

FIG. 11 shows an example of the processing sequence of the first modification in the third embodiment. Although FIG. 11 and FIG. 10 share many parts, some procedures are different. Here, the points in FIG. 11 different from FIG. 10 will be mainly described.

First, in FIG. 10, connection addition (Addition) and connection start (Activation) in a two-way connection are simultaneously instructed from the macro base station 10a to the small base station 10b by a DC request of S208. These are simultaneously instructed from the macro base station 10a to the radio terminal 20 by RRC Connection Re-configuration of S211. Although details are omitted, these are procedures that follow a general handover procedure in the LTE system.

On the other hand, in FIG. 11, the addition of connection in the two-way connection is notified from the macro base station 10a to the small base station 10b by the DC request of S308. On the other hand, the start (activation) of the two-way connection is notified from the macro base station 10a to the small base station 10b by DC Activation in S313. At this time, in S314, the small base station 10b transmits a DC Activation ACK that is a DC response signal to the macro base station 10a.

In FIG. 11, addition of connection in the two-way connection is notified from the macro base station 10a to the radio terminal 20 by the RRC Connection Re-configuration of S311. On the other hand, the start (activation) of the two-way connection is notified from the macro base station 10a to the wireless terminal 20 by the MAC activation in S315. Although details are omitted, these are procedures that follow the general carrier aggregation procedure in the LTE system.

11 that are not mentioned above in the processing in FIG. 11 may be performed in the same manner as the corresponding processing in FIG. 10, and thus the description thereof is omitted here.

The second modification in the third embodiment relates to a change in the identifier space for RNTI. In the processing sequence of the third embodiment shown in FIG. 10, the small base station 10b changes the identifier space for RNTI in S209 based on the C-RNTI included in the DC request transmitted in S208. However, transmission / reception of RRC signals after random access procedures (S204 to S206) and measurement report (S207) generally require tens to hundreds of milliseconds (tens to hundreds of subframes). Therefore, while transmitting and receiving an RRC signal and a measurement report, # N1, which is the C-RNTI assigned to the radio terminal 20 by the macro base station 10a in S202, the small base station 10b communicates with the other radio terminals 20 under its control. It is considered that there is still a possibility of being assigned. Therefore, in the second modification of the third embodiment, the macro base station 10a sends out the C-RNTI assigned to the wireless terminal 20 that can be connected in two ways to the small base station 10b.

FIG. 12 shows an example of the processing sequence of the second modified example in the third embodiment. Although FIG. 12 and FIG. 10 share many parts, some procedures are different. Here, FIG. 12 will be described focusing on differences from FIG.

In FIG. 12, the macro base station 10a notifies the small base station 10b of # N1, which is the C-RNTI allocated to the two-way connectable wireless terminal 20 in S404 (this notification is referred to as C-RNTI Reservation). To do). Then, in 405, the small base station 10b changes the identifier space for RNTI based on # N1, which is C-RNTI notified by C-RNTI Reservation in S404. As a result, the identifier space for RNTI is changed immediately after the random access response in S403. Therefore, according to the processing sequence of FIG. 12, the small base station 10b assigns the C-RNTI assigned to the wireless terminal 20 by the macro base station 10a to the other wireless terminals 20 under its control, as compared to the processing sequence of FIG. The possibility is likely to decrease.

12 that are not mentioned above in the processing in FIG. 12 may be performed in the same manner as the corresponding processing in FIG. 10, and thus the description thereof is omitted here.

Note that the second modification of the third embodiment shown in FIG. 12 has the above-described advantages, but the identifier space for C-RNTI in the small base station 10b may be wasted. Please be careful. This is because the small base station 10b excludes the C-RNTI assigned to the wireless terminal 20 when it is undecided whether the wireless terminal 20 capable of two-way connection makes a two-way connection with the small base station 10b. is there. Furthermore, when there are a plurality of small base stations 10b under the control of the macro base station 10a, the C-RNTI applied to the two-way connectable radio terminal 20 needs to be excluded in all the small base stations 10b. Waste can be significant. On the other hand, in the third embodiment shown in FIG. 10, such waste is not generated.

According to the third embodiment described above and various modifications thereof, the macro base station 10a notifies the small base station 10b of the C-RNTI assigned to the wireless terminal 20 that can be connected in two ways. As a result, the C-RNTI allocated to the two-way connectable radio terminal 20 under the macro base station 10a and the C-RNTI of the radio terminal 20 under the small base station 10b do not overlap. It is possible to avoid problems such as erroneous reception associated with the original connection. As a result, it is possible to realize terminal management that is desirable for realizing two-way connection.

[Fourth embodiment]
The fourth embodiment is one in which the first embodiment is applied to an LTE system and is a subordinate concept of the first embodiment. Specifically, in the fourth embodiment, a plurality of C-RNTIs are allocated to the wireless terminal 20 that can be connected in two ways, thereby solving the above-described problem of erroneous reception associated with the two-way connection. .

The basic concept of the fourth embodiment will be described. In the above-described second to third embodiments and various modifications thereof, it is assumed that one C-RNTI is allocated to the radio terminal 20. Therefore, as detailed above in the location of the above problem, if no countermeasure is taken, the same C-RNTI as the C-RNTI of the wireless terminal 20 performing the two-way connection is transmitted to the radio under the small base station 10b. There is a possibility of being assigned to the terminal 20.

Here, consider that a plurality of C-RNTIs are allocated to the wireless terminal 20 capable of two-way connection. That is, it is assumed that the C-RNTI is independently assigned to each of the two connections in the wireless terminal 20 capable of two-way connection.

Even in this case, basically, the macro base station 10a allots a plurality of C-RNTIs to the radio terminal 20 capable of two-way connection. This is because, according to the standard specification, even a radio terminal 20 that can be connected in two ways has only one RRC, and therefore it is necessary for the macro base station to centrally allocate a plurality of C-RNTIs for the radio terminal 20. .

Therefore, even when a plurality of C-RNTIs are allocated to the wireless terminal 20 capable of two-way connection, the same as when one C-RNTI is allocated to the wireless terminal 20 capable of two-way connection. A problem occurs. That is, even when a plurality of C-RNTIs are allocated to the wireless terminal 20 capable of two-way connection, two-way connection is performed if no measures are taken as in the case of the above problem location. There is a possibility that the same C-RNTI as the C-RNTI of the radio terminal 20 is allocated to the radio terminal 20 under the small base station 10b. Hereinafter, a fourth embodiment that is an embodiment based on this viewpoint will be described.

FIG. 13 shows an example of a processing sequence in the wireless communication system according to the fourth embodiment. FIG. 13 corresponds to the processing sequence of FIG. 10 in the second embodiment, and has a procedure similar to handover as an example. Although FIG. 13 and FIG. 10 share many parts, some procedures are different. Here, FIG. 13 will be described with a focus on differences from FIG.

In S508 of FIG. 13, the macro base station 10a assigns a new C-RNTI # N2 to the radio terminal 20. This new C-RNTI # N2 is used for connection between the two-way connectable radio terminal 20 and the small base station 10b. At this time, the macro base station 10a may assign an arbitrary value from the entire identifier space that can be used as the C-RNTI to the wireless terminal 20 that can be connected in two ways. In other words, at this time, the small base station 10b selects an arbitrary value from the space 2 (identifier space that can be used as C-RNTI) in the identifier space for RNTI illustrated in FIGS. It can be assigned to the connectable wireless terminal 20.

The DC request transmitted in S509 of FIG. 13 includes # N2, which is the C-RNTI assigned to the wireless terminal 20 to which the macro base station 10a can perform two-way connection in S508, unlike S208 of FIG. The DC request in S509 may or may not include # 1 which is another C-RNTI.

In S510 of FIG. 13, the small base station 10b changes the RNTI identifier space based on # N2 which is C-RNTI included in the DC-REQUEST received in S509. This may be performed in the same manner as S209 in FIG.

In S512 of FIG. 13, the macro base station 10a transmits an RRCRRConnection Re-configuration message, which is an RRC signal, to the wireless terminal 20 via the PDSCH, similarly to S211 of FIG. Here, it is noted that the RRC Connection Re-configuration message in S512 includes # N2, which is a C-RNTI used for connection between the two-way connectable wireless terminal 20 and the small base station 10b, unlike S211. I want to be.

In FIG. 13, thereafter, the same procedure as in FIG. 10 is performed, and in S516, the wireless terminal 20 enters a two-way connection state. At this time, the radio terminal 20 starts to use # N2 which is C-RNTI allocated from the small base station 10b. That is, after S516, the radio terminal 20 can receive DCI using # N2 as C-RNTI and receive downlink data associated with DCI and transmit uplink data even with the small base station 10b. . At this time, since the connection (C-RNTI is # N1) between the wireless terminal 20 and the macro base station 10a established in S506 is also maintained, two-way connection is realized in the wireless terminal 20. Please keep in mind.

As described above, according to the processing sequence of the wireless communication system according to the fourth embodiment shown in FIG. 13, by assigning a plurality of C-RNTIs to the two-way connectable wireless terminal 20, It is possible to avoid problems such as erroneous reception associated with the two-way connection.

Hereinafter, various modifications of the above-described fourth embodiment will be described.

The first modification in the fourth embodiment relates to a procedure for realizing a two-way connection. In the processing sequence of the fourth embodiment shown in FIG. 13, two-way connection is realized by a procedure similar to handover. On the other hand, the 1st modification in 4th Embodiment implement | achieves 2-way connection by the procedure similar to a carrier aggregation.

FIG. 14 shows an example of the processing sequence of the first modification in the fourth embodiment. FIG. 14 shows the processing sequence of the fourth embodiment shown in FIG. 13 (procedure similar to handover) and the processing sequence of the first modification of the third embodiment shown in FIG. 11 (procedure similar to carrier aggregation). ). Therefore, the detailed description about FIG. 14 is omitted here.

The second modification in the fourth embodiment is a further modification of the first modification in the fourth embodiment.

FIG. 15 shows an example of a processing sequence of the second modified example in the fourth embodiment. For example, in the processing sequence of the fourth embodiment shown in FIG. 13, the wireless terminal 20 capable of two-way connection uses # N1, which is C-RNTI assigned by the macro base station 10a, in the random access response (S503) Temporary C- This is received as RNTI, and this is the same in other processing sequences. However, in the processing sequence of FIG. 13 and the like, the wireless terminal 20 capable of two-way connection uses # N2 which is C-RNTI (or Temporary C-RNTI) assigned by the macro base station 10a in a message or the like different from the random access response. Receiving.

On the other hand, in FIG. 15, the wireless terminal 20 capable of two-way connection also receives # N2, which is the C-RNTI assigned by the macro base station 10a, as Temporary C-RNTI in the random access response (S718). Is. Here, in a normal non-collision type random access procedure, Temporary C-RNTI stored in the random access response is ignored by the radio terminal 20. However, it should be noted that in this modification, the radio terminal 20 interprets the Temporary C-RNTI as a C-RNTI assigned to itself.

By the way, in the fourth embodiment described above and the modifications thereof, the macro base station 10a assigns # N2, which is a C-RNTI used by the terminal 20 capable of two-way connection to connect to the small base station 10b. It is explained on the assumption. This premise is based on the fact that there is only one RRC even if the wireless terminal 20 is capable of two-way connection in the standard specification as described above. However, the C-RNTI may be assigned by the MAC. In that case, the small base station 10b (the MAC in the small base station 10b) can assign # N2, which is a C-RNTI used for the terminal 20 capable of two-way connection to connect to the small base station 10b. The MAC in the macro base station 10a can also assign # N2, which is a C-RNTI used for the terminal 20 that can be connected in two ways to connect to the small base station 10b. In these cases as well, although details are omitted, it is possible to implement the present invention based on the above-described embodiments and modifications.

According to the fourth embodiment described above and various modifications thereof, by assigning a plurality of C-RNTIs to the wireless terminal 20 capable of two-way connection, the above-described problems such as erroneous reception due to the two-way connection are obtained. It can be avoided. As a result, it is possible to realize terminal management that is desirable for realizing two-way connection.

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

FIG. 16 shows an example of a sequence diagram of the other embodiment (part 1). In the embodiment shown in FIG. 16, when a conventional radio terminal 20 is connected to the small base station 10b, the macro base station 10a is inquired about whether or not the C-RNTI assigned to the radio terminal 20 can be used ( S803).

In FIG. 16, when the small base station 10b does not give permission to the inquiry from the macro base station 10a (S804), the small base station 10b reselects C-RNTI and makes an inquiry again to the macro base station 10a (S805 to S806). On the other hand, when the small base station 10b gives permission to the inquiry from the macro base station 10a (S808), the small base station 10b notifies the radio terminal 20 of C-RNTI (S809). At this time, the macro base station 10a changes the identifier space so that the C-RNTI permitted to the small base station 10b is not allocated to the other wireless terminal 20 capable of two-way connection (S807). By doing so, similarly to the second embodiment shown in FIG. 10 and the like, it is possible to avoid the above-described problems such as erroneous reception due to the two-way connection. As a result, it is possible to realize terminal management that is desirable for realizing two-way connection.

FIG. 17 shows an example of a sequence diagram of the other embodiment (part 2). The embodiment shown in FIG. 17 is based on the premise that both the macro base station 10a and the small base station 10b are free to allocate C-RNTI to the radio terminal 20 (S901 to S913). However, the C-RNTI assigned by the small base station 10b to the first wireless terminal 20a capable of two-way connection in the macro base station 10a overlaps with the C-RNTI already assigned to the second wireless terminal 20b under its control. When recognizing that it has been performed (S914), another C-RNTI is reassigned to the second radio terminal 20b (S915 to S918). By doing so, similarly to the second embodiment shown in FIG. 10 and the like, it is possible to avoid the above-described problems such as erroneous reception due to the two-way connection. As a result, it is possible to realize terminal management that is desirable for realizing two-way connection.

Other embodiments (part 3) notify or exchange the RNTI identifier space (identifier space table) each time. In the second embodiment and its modification described above, the identifier space is set exclusively when the base station 10 is installed. However, the identifier space table can be set exclusively after notifying or exchanging the identifier space table between the base stations 10 at the time of setting the two-way connection or at the time of the handover involving the two-way connection. In this case, the identifier space table notified or exchanged between the base stations 10 may be any of those illustrated in FIG. 4 to FIG. 9, or may operate even if it is illustrated in FIG. It is. This can also be realized by the macro base station 20a notifying the small base station 10b of a list of C-RNTIs permitted to be used.

Finally, it goes without saying that information element names, parameter names, and the like in control signals transmitted and received by the base station 10 and the wireless 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. 18, the network configuration of the wireless communication system 1 of each embodiment will be described. As illustrated in FIG. 18, the wireless communication system 1 includes a base station 10 and a wireless terminal 20. The base station 10 forms a cell C10. The radio terminal 20 exists in the cell C10. Note that in this application, the base station 10 and the wireless terminal 20 may be referred to as wireless stations.

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

The base station 10 may separate the wireless communication function with the wireless 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 base station 10 may be a base station 10 of various scales in addition to a small base station 10 (including a micro base station 10, a femto base station 10 and the like) such as a macro base station 10 and a pico base station 10. . Further, when a relay station that relays radio communication between the base station 10 and the radio terminal 20 is used, the relay station (transmission / reception with the radio terminal 20 and its control) is also included in the base station 10 of the present application. Good.

Meanwhile, the wireless terminal 20 communicates with the 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. In addition, when a relay station that relays wireless communication between the base station 10 and the wireless terminal 20 is used, the relay station (transmission / reception with the base station 10 and its control) is also included in the wireless terminal 20 of this paper. 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 aspect of distribution / integration of each component of the base station 10 and the wireless terminal 20 is not limited to the aspect of the first embodiment, and all or a part thereof depends on various loads, usage conditions, and the like. Thus, it can be configured to be functionally or physically distributed and integrated in arbitrary units. For example, the memory may be connected as an external device of the base station 10 and the wireless terminal 20 via a network or a cable.

[Functional Configuration of Each Device in Radio Communication System of Each Embodiment]
Next, the functional configuration of each device in the wireless communication system of each embodiment will be described based on FIG. 19 to FIG.

FIG. 19 is a functional block diagram showing an example of the configuration of the base station 10. As illustrated in FIG. 19, the base station 10 includes, for example, a wireless transmission unit 11, a wireless 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 transmission unit 11, the base station 10 (macro base station 10a, small base station 10b (first small base station 10b1, second small base) in FIG. 3 and FIGS. Each radio signal (arrow in the figure) transmitted to the radio terminal 20 (including the first radio terminal 20a and the second radio terminal 20b). The radio signal transmitted by the radio transmission unit 11 is not limited thereto, and includes any radio signal transmitted from each base station 10 to the radio terminal 20 in each of the above embodiments and modifications.

The wireless receiving unit 12 receives a data signal and a control signal 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.

As a specific example of the radio signal received by the radio receiver 12, each base station 10 (macro base station 10a, small base station 10b (first small base station 10b1, second small base) in FIG. 3 and FIGS. Each radio signal (indicated by an arrow in the figure) received from the radio terminal 20 (including the first radio terminal 20a and the second radio terminal 20b). The signals received by the wireless reception unit 12 are not limited to these, and include any wireless signal that each base station 10 receives from the wireless terminal 20 in each of the above embodiments and modifications.

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 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 base station 10.

As a specific example of the process controlled by the control unit 13, in FIG. 3 and FIGS. 10 to 17, each base station 10 (macro base station 10a, small base station 10b (first small base station 10b1, second small base station 10b2 ) Includes control for each signal (arrow in the figure) transmitted and received, and control for each process (rectangle in the figure) performed by each base station 10. The process which the control part 13 controls is not restricted to these, but includes the control regarding all the processes which each 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 each base station 10 (macro base station 10a, small base station 10b (first small base station 10b1, second small base station 10b2) in the above-described embodiments and modifications. ) Including any information that can be stored.

The communication unit 15 transmits / receives data and control information to / from another base station 10 or the like via a wired signal or the like (which may be a wireless signal). Specific examples of wired signals transmitted and received by the communication unit 15 include the base stations 10 (macro base station 10a, small base station 10b (first small base station 10b1, second small base) in FIGS. Each wired signal transmitted / received to / from the other base station 10 (including the macro base station 10a and the small base station 10b (including the first small base station 10b1 and the second small base station 10b2)). Etc. (arrows in the figure). The wired signals and the like transmitted and received by the communication unit 15 are not limited to these, and include all wired signals and the like that are transmitted and received by each base station 10 from the other base station 10 and the like in the above embodiments and modifications.

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

FIG. 20 is a functional block diagram illustrating an example of the configuration of the wireless terminal 20. As illustrated in FIG. 20, 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 base station 10. The radio signal transmitted by the radio transmission unit 21 can include arbitrary user data, control information, and the like (encoded or modulated) for each base station 10.

As a specific example of the radio signal transmitted by the radio transmission unit 21, the radio terminal 20 (including the first radio terminal 20a and the second radio terminal 20b) in FIG. 3 and FIG. 10 to FIG. Examples include radio signals (arrows in the figure) transmitted to the station 10a and the small base station 10b (including the first small base station 10b1 and the second small base station 10b2). The wireless signal transmitted by the wireless transmission unit 21 is not limited to these, and includes any wireless signal that the wireless terminal 20 transmits to each base station 10 in each of the above embodiments and modifications.

The wireless receiving 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 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 from each base station 10.

As a specific example of the radio signal received by the radio reception unit 22, the radio terminal 20 (including the first radio terminal 20a and the second radio terminal 20b) in FIG. 3 and FIG. 10 to FIG. 10a, each radio signal (arrow in the figure) received from the small base station 10b (including the first small base station 10b1 and the second small base station 10b2). The signals received by the wireless reception unit 22 are not limited to these, and include any wireless signal that the wireless terminal 20 receives from each 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 base station 10 to the wireless transmission unit 21. The control unit 23 inputs data and control information received from each base station 10 from the wireless 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 signals transmitted and received by the wireless terminal 20 (including the first wireless terminal 20a and the second wireless terminal 20b) in FIGS. 3 and 10 to 17 (in the drawing). Control for each process (rectangle in the figure) performed by the wireless terminal 20. 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 wireless terminal 20 may transmit and receive wireless signals to / from wireless communication devices other than the base station 10 via the wireless transmission unit 21 and the wireless reception unit 22.

[Hardware Configuration of Each Device in Radio Communication System of Each Embodiment]
The hardware configuration of each device in the wireless communication system of each embodiment and each modification will be described with reference to FIGS.

FIG. 21 is a diagram illustrating an example of a hardware configuration of the base station 10 (including the macro base station 10a and the small base station 10b (including the first small base station 10b1 and the second small base station 10b2)). As shown in FIG. 21, the base station 10 includes, as hardware components, for example, an RF (Radio Frequency) circuit 112 including an antenna 111, a processor 113, a memory 114, and a network IF (Interface) 115. . 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 base station 10 may include an auxiliary storage device (such as a hard disk) not shown.

The correspondence between the functional configuration of the base station 10 shown in FIG. 19 and the hardware configuration of the base station 10 shown in FIG. 21 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. 22 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. 22, 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. 20 and the hardware configuration of the wireless terminal 20 illustrated in FIG. 22 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.

DESCRIPTION OF SYMBOLS 1 Wireless communication system 2 Network 3 Network apparatus 10 Base station C10 Cell 20 Wireless terminal

Claims (14)

A first radio station identifier that is selected and assigned from a first radio station identifier set to a first radio station that allows a first base station to communicate in parallel with the first base station and the second base station; The first radio station identifier is selected and assigned to the second radio station from the second radio station identifier set that is at least partially overlapped with the first radio station identifier set so that the first radio station identifier does not overlap with the first radio station identifier set. At least one of the base station and the second base station performs control,
The first radio station communicates with at least the first base station using the first radio station identifier;
The wireless communication method in which the second wireless station communicates with the second base station using the second wireless station identifier. The first base station assigns the first wireless station identifier to the first wireless station from a third wireless station identifier set that is part of the first wireless station identifier set;
The radio communication method according to claim 1, wherein the second base station allocates the second radio station identifier set not included in the third radio station identifier set to the second radio station. The radio communication method according to claim 2, wherein the first base station determines the third radio station identifier set from the first radio station identifier set, and notifies the second base station of the third radio station identifier set. . The first base station is a part of the second radio station identifier set, and the third radio station identifier is not overlapped with a fourth radio station identifier set used in random access processing in the second base station. The wireless communication method according to claim 3, wherein the set is determined. The radio communication method according to claim 4, wherein the second base station determines the fourth radio station identifier set and notifies the first base station of the fourth radio station identifier set. The radio communication method according to claim 4, wherein the first base station determines the fourth radio station identifier set and notifies the second base station of the fourth radio station identifier set. The radio communication method according to any one of claims 1 to 6, wherein the first radio station can perform individual communication in parallel with the first base station and the second base station. The first base station notifies the second base station of the first radio station identifier assigned to the first radio station;
The radio communication method according to claim 1, wherein the second base station performs control so as not to assign the notified first radio station identifier as the second radio station identifier. The second base station notifies the first base station of a temporary radio station identifier selected from the second radio station identifier set;
The second base station assigns the temporary wireless station identifier as the second wireless station identifier when the first base station is given an assignment permission for the temporary wireless station identifier;
The first base station controls the temporary radio station identifier not to be allocated as the first radio station identifier when the allocation permission for the temporary radio station identifier is given to the second base station. The wireless communication method described. A first base station;
A second base station;
A first radio station;
A wireless communication system comprising: a second wireless station;
A first wireless station identifier that is selected and assigned from the first wireless station identifier set to the first wireless station that can communicate with the first base station and the second base station in parallel with the first base station; The second base station does not overlap the second wireless station identifier selected and assigned to the second wireless station by selecting from the second wireless station identifier set at least partially overlapping with the first wireless station identifier set. A control unit for controlling is provided in at least one of the first base station and the second base station,
The first radio station includes a first radio communication unit that communicates with at least the first base station using the first radio station identifier;
A said 2nd radio station is a radio | wireless communications system provided with the 2nd communication part which communicates with a said 2nd base station using the said 2nd radio station identifier. A base station,
A first wireless station identifier that is selected and assigned from a first wireless station identifier set to a first wireless station that allows the base station to communicate in parallel with the base station and another base station; A control unit that performs control so that a second radio station identifier selected and assigned to a radio station from a second radio station identifier set that is at least partially overlapped with the first radio station identifier set does not overlap;
A wireless communication unit that communicates with the first wireless station using the first wireless station identifier;
A base station. A base station,
A first radio station identifier that is selected and assigned from the first radio station identifier set to a first radio station in which another base station can communicate in parallel with the base station and the other base station; A control unit that performs control so that a second radio station identifier selected and assigned from a second radio station identifier set that is at least partially overlapped with the first radio station identifier set for a radio station does not overlap;
A wireless communication unit that communicates with the second wireless station using the second wireless station identifier;
A base station. A radio station,
A wireless communication unit capable of communicating in parallel with the first base station and the second base station;
The first base station is a first radio station identifier that the first base station selects and assigns to the radio station from the first set of radio station identifiers, and the second base station assigns the first radio station identifier to another radio station. A storage unit for storing the first wireless station identifier controlled so as not to overlap with a second wireless station identifier selected and assigned from a second wireless station identifier set that at least partially overlaps the set; and
The wireless communication unit communicates with at least the first base station using the first wireless station identifier;
Radio station. A radio station,
Control so that the first base station does not overlap with the first radio station identifier that is selected from the first radio station identifier set and assigned to other radio stations that can communicate with the first base station and the second base station in parallel. The second radio station identifier, and the second base station selects and assigns to the radio station from the second radio station identifier set that at least partially overlaps the first radio station identifier set. A storage unit for storing two radio station identifiers;
A radio station comprising: a radio communication unit that communicates with the second base station using the second radio station identifier.

Images