JP2008311911A - Base station, radio terminal and radio communicating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable each base station to allocate a channel while avoiding collision in using a communication channel between base stations. <P>SOLUTION: A candidate for a communication channel to be allocated to an allocation object terminal being a terminal belonging to a certain base station is determined among a plurality of communication channels, a training signal determined in each base station of each of the plurality of communication channels is transmitted from the allocation object terminal to the certain base station in the candidate for a communication channel, the candidate for a communication channel detects the training signal transmitted from a terminal within a communication area of the certain base station, and the candidate for a communication channel is allocated to the allocation object terminal when the candidate for a communication channel does not detect a training signal having a priority higher than that of the training signal transmitted from the allocation object terminal on the basis of the priority of each of a plurality of training signals determined in each of the plurality of communication channels. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a base station, a radio terminal, and a radio communication method, for example, a channel assignment method in a cellular radio communication system.

As a method for avoiding channel collision in a wireless communication system, there is a method in which each terminal broadcasts a reservation status of a channel and a priority based on a traffic type or the like to the surroundings using a beacon. When contention for channel reservation occurs, terminals with higher priority use the channel to avoid channel collision in an autonomous and distributed manner (Japanese Patent Laid-Open No. 2005-354326).
Japanese Patent Laid-Open No. 2005-354326

  However, in this method, since it is assumed that each terminal can directly communicate the channel reservation status with a beacon, a system in which terminals cannot communicate with each other like terminals in adjacent cells of a cellular communication system. Has problems that are not applicable.

  The present invention provides a base station, a wireless terminal, and a wireless communication method capable of assigning a channel in each base station while avoiding a collision of use of a communication channel between base stations.

The base station as one aspect of the present invention is:
A base station that performs communication by allocating at least one communication channel among a plurality of communication channels to a terminal in a communication area, and is arranged so that the communication area partially overlaps with another base station,
Determining means for determining a communication channel candidate to be allocated to an allocation target terminal, which is a terminal in the communication area, from among the plurality of communication channels;
First information in which the x-th training signal different from the other base stations to be used among the first to n-th training signals defined in advance is determined in each of the plurality of communication channels, and the plurality of communications Information holding means for holding second information defining priority of the first to n-th training signals in each of the channels;
Instruction means for sending instruction data to instruct the allocation target terminal to transmit the x-th training signal determined by the first information in the candidate communication channel;
Detecting means for detecting a training signal transmitted from a terminal in the communication area in the communication channel candidate;
Allocating means for allocating the communication channel candidate determined by the determining means to the allocation target terminal when a training signal having a higher priority than the x-th training signal is not detected in the communication channel candidates;
Assigning means for assigning candidates to the assignment target terminal;
Is provided.

A wireless terminal as one aspect of the present invention is:
A wireless terminal that communicates by using at least one communication channel assigned from one of a plurality of communication channels and one of base stations arranged so that communication areas overlap each other,
Candidate information acquisition means for acquiring candidate information indicating communication channels that are candidates for allocation from a base station that is one of the base stations;
Training signal transmitting means for transmitting a training signal predetermined for each base station in each of the plurality of communication channels to the certain base station in a communication channel candidate indicated by the candidate information acquired by the candidate information acquiring means When,
Notification acquisition means for acquiring a notification of a communication channel assigned by the certain base station from the certain base station;
Is provided.

A wireless communication method as one aspect of the present invention includes:
A wireless communication method for selecting and assigning to a terminal a communication channel for communicating with one of base stations arranged so that communication areas overlap each other,
A communication channel candidate to be allocated to an allocation target terminal that is a terminal belonging to a base station that is one of the base stations is determined from the plurality of communication channels;
A training signal predetermined for each base station in each of the plurality of communication channels is transmitted from the allocation target terminal to the certain base station in the communication channel candidates,
Detecting a training signal transmitted from a terminal in a communication area of the certain base station in the communication channel candidate;
Based on the priority of each of the plurality of training signals predetermined for each of the plurality of communication channels, a training signal having a higher priority than the training signal transmitted from the allocation target terminal is detected in the communication channel candidates. If not, assign the communication channel candidate to the allocation target terminal,
It is characterized by that.

  According to the present invention, it is possible to allocate a channel in each base station while avoiding a collision in use of a communication channel between the base stations.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a configuration example of a cellular radio communication system according to an embodiment of the present invention.

  This cellular radio communication system includes a plurality of base stations CS1 and CS2, a base station controller 11 that controls the plurality of base stations CS1 and CS2, and a plurality of terminals PS1A to PS1C and PS2A to PS2C. Base stations CS1 and CS2 are arranged such that their communication areas partially overlap. A plurality of base stations CS 1 and CS 2 and the base station control device 11 are connected via a wired network 12. A plurality of base stations do not directly exchange channel (communication channel) reservation information and channel assignment information, and the base stations CS1 and CS2 operate in an autonomous and distributed manner.

  In the present embodiment, the base stations do not share channel reservation information and channel allocation information with each other, thereby avoiding channel use conflicts between base stations that are problematic in the overlapping area of the communication area. However, it is intended to enable flexible channel allocation in units of several frames.

  Hereinafter, the cellular radio communication system of FIG. 1 will be described in more detail.

  FIG. 2 is a diagram showing a frame configuration example used in the cellular radio communication system of FIG.

  One frame is composed of a plurality of control channels CCH (n) whose time length is slot time and frequency width is channel width, and a plurality of communication channels TCH (n). Method), the downlink and the uplink are time-divided. One super frame is composed of k frames. CCH (n) and TCH (n) are a control channel with channel number n and a communication channel with channel number n, respectively.

  Since each base station basically uses a downlink and an uplink as a pair, the number of downlink channels is equal to the number of uplink channels, and each channel is described with the same channel number.

  A certain control channel is constantly used continuously by the base station, and is used for transmission of broadcast information and paging information and a connection procedure for assigning a circuit-switched communication channel to a terminal. On the other hand, the communication channel is used for voice communication and data communication between the base station and the terminal, and is a type of channel that is temporarily used as needed unlike the control channel.

  FIG. 3 is a diagram illustrating a configuration example of a superframe. The channel number of the control channel is defined by the superframe period. In the example in the figure, one superframe is composed of four frames, and there are 16 types of control channels, CCH (1) to CCH (16). It is assumed that each base station selects one of the control channels with the lowest interference level and regularly uses it by measuring the interference level of the control channel.

  FIG. 4 is a diagram illustrating an example of a list of control channel numbers used by the base station. Here, the base station number is up to 16, but since the control channel itself is reused at geographically distant points, the limit of the number of base stations is 16 in an actual cellular radio communication system. It doesn't mean that. The interpretation that the number of base station coverage overlaps at a point is at most 16 is correct. Hereinafter, as shown in FIG. 4, the number of the control channel used by each base station is treated as the base station number. That is, the base station using the control channel CCH (1) is CS1, the base station using the control channel CCH (2) is CS2,..., And the base station using the control channel CCH (16) is CS16.

  FIG. 5 is a diagram illustrating a configuration example of a control channel and a communication channel. Here, it is assumed that an OFDM (Orthogonal Frequency Division Multiplexing) scheme or an SC (Single Carrier) scheme with a guard interval added is used as a downlink and uplink radio access scheme. In the case of the OFDM scheme, each channel is composed of a plurality of OFDM symbols composed of a plurality of subcarriers, and the OFDM symbol includes a guard interval (GI for avoiding propagation path propagation delay and multipath interference). : Guard Interval) is added. In the SC scheme, each channel is composed of a plurality of single carrier data blocks (SC data blocks) each composed of a plurality of modulation symbols. When a plurality of communication channels are allocated to terminals in the same slot, there is no particular limitation on the allocation method in the case of OFDM symbols, but in the case of SC data blocks, it is necessary to allocate communication channels that are continuous in frequency. As shown in FIG. 5, if the channel configuration is such that the OFDM symbol length is equal to the block length of the SC data block and the guard interval length is also equal, the OFDM system terminal and the SC system may be included in the same system. Terminals can coexist. Further, in addition to a completely frequency-divided channel configuration as shown in FIG. 5, each channel may be defined as a plurality of subcarriers bundled at regular intervals in a comb tooth shape. Hereinafter, for the sake of simplification of discussion, it is assumed that the radio access communication between the base station and the terminal uses the OFDM scheme for both downlink and uplink unless otherwise noted.

  FIG. 6 is a diagram illustrating classification of communication channels. Communication channels are classified into two types, circuit-switched channels and packet-switched channels, depending on how they are used. As each name indicates, a circuit-switched channel is a type of channel that is once used between a base station and a terminal and continues to be used until the connection is terminated. This is a type of channel that uses only a certain number of frames at a time (temporarily assigned and used).

  Circuit switched channels are further classified into two types according to the purpose of use: reserved allocation channels and circuit switched data channels. The reservation allocation channel is used to allocate a packet switching channel or a circuit switching data channel to the terminal. The circuit switched data channel is a channel for transmitting traffic used for circuit switching such as voice communication, and the packet switched channel is a channel for transmitting traffic such as packet communication.

  FIG. 7 is a diagram illustrating a first configuration example of the channel assignment section. The channel allocation section is a section periodically composed of a plurality of frames, and is a unit of time for the base station to perform channel allocation of the packet switching channel to the terminal. In the example of FIG. 4, four consecutive frames correspond to one channel allocation section. The base station assigns each communication channel to a terminal for each channel assignment section. However, in the first configuration example, it is assumed that the base stations are synchronized in time through GPS (Global Positioning System) or the base station control device 11, and the channel allocation section of each base station is synchronized. .

  FIG. 8 is a diagram illustrating a second configuration example of the channel allocation section. The difference from the first configuration example in FIG. 7 is that the channel assignment sections of the base stations are not necessarily synchronized, and when the channel assignment section is composed of N frames, There are N allocation start timings. In this example, since the channel allocation section is composed of four frames, there are four allocation start timings as shown in FIGS. 8 (A) to 8 (D). However, also in the second configuration example, each base station needs to be synchronized in time through a GPS (Global Positioning System) or a base station control device.

  FIG. 9 is a diagram illustrating a basic configuration example of a circuit switching channel. A characteristic of the circuit switching channel is that the uplink channel is divided into a circuit switching training area A1, a BF (beamforming) training area A2, and a data area as shown in FIG. 9A. The downlink channel consists only of the data area as shown in FIG. In the circuit-switched training area in the uplink channel, a circuit-switched training signal for indicating a circuit-switched channel is transmitted from the terminal. In the BF (Beam Forming) training area, a training signal for beamforming weight calculation in the base station is transmitted from the terminal. In the data area in the uplink channel and the downlink channel, actual voice data at the time of voice communication, a data portion of a reservation allocation channel described later, and the like are transmitted.

  FIG. 10 is a diagram illustrating a configuration example of a circuit switching training area and a BF training area. In the figure, one grid corresponds to one subcarrier of one OFDM symbol or one frequency component of one SC data block. In addition, since it is possible to calculate the weight of the beamforming using the circuit switching training signal itself, in such a case, the BF training area can be made a part of the data area. The role and usage of the circuit switching training area and BF training area will be described in detail later.

  The configuration of the circuit switched data channel is the same as the configuration example of FIG. In a circuit switched data channel for transmitting data such as voice communication, one terminal uses the entire channel for both uplink and downlink. When a fixed number of circuit-switched data channels are required for voice communication or the like, they are assigned directly to the terminal through the control channel.

  FIG. 11 is a diagram illustrating a configuration example of a packet switching channel. A characteristic of the packet switching channel is that the uplink channel is divided into a packet switching training area and a data area in addition to the circuit switching training area and the BF training area as shown in FIG. The downlink channel consists only of the data area as shown in FIG. The circuit switching training area in the uplink channel is defined in the same way as the circuit switching channel, but this area is not normally used in the packet switching channel. This is because in this area, the circuit switching channel is used for the purpose of distinguishing between the circuit switching channel and the packet switching channel in order to send a unique circuit switching training signal. An example of the exceptional use of the circuit switched training area in the packet switched channel will be described later.

  In the packet switching training area, a packet switching training signal is transmitted from the terminal. The packet switching training signal is autonomously distributed among base stations using the priority based on the type of packet switching training signal when the request for using the communication channel in the next channel allocation section competes. Is to make a decision. That is, when the base station wants to use a communication channel in the channel allocation section, the base station transmits a packet switching training signal to the terminal in one predetermined packet switching training area in the previous section. Become.

  FIG. 12 is a diagram illustrating a configuration example of a packet exchange training area. The packet exchange training area is divided into a plurality of areas. In the example of FIG. 12, the packet switching training areas B1 to B4 are divided into four areas. The reason for dividing into a plurality of areas in this way is to make it easy to simultaneously receive and detect a plurality of packet-switched training signals transmitted from neighboring base stations. If the number of packet-switched training signals is larger than the number of packet-switched training areas defined in the packet-switched channel, the packet-switched training areas at the same position are time-divided for each frame within the channel assignment section. It may be used by another base station (see FIG. 22 described later).

  In particular, as shown in FIG. 8, when there is an offset in the start timing of the channel assignment section, each base station's packet exchange training area is present in the last frame of the section immediately before the channel assignment section. By setting the packet switching training area and the start timing offset, each base station can always receive a packet switching training signal immediately before the channel allocation period. The weight calculation for beam forming in this frame can be easily realized. More detailed roles and usage of the packet switching training area will be described later.

  In the data area, an actual data portion (payload portion) of packet communication, upper layer data, and the like are transmitted. In the packet-switched channel, the packet-switched training area is an area shared by a plurality of base stations for the next channel allocation section, so it can be considered that it is independent of the data area, and the channel is allocated. Meaning means assigning a data area.

  The BF training signal used in the BF training area is received from the terminal in the packet switching channel where the right to use is obtained for weight calculation for beamforming when the right to use the packet switching channel is obtained in a certain channel allocation section. Sent.

  Here, the method of dividing the training region into a plurality of regions in FIG. 10 and FIG. 12 is not limited to subcarrier (frequency component) units as shown in FIG. Combinations of these can also be used. However, since the arrival timing of a training signal from a terminal under the control of another base station cannot be controlled in general, in order to maintain the orthogonality of the training signal, subdivisions such as those shown in FIGS. An exclusive division method such as division for each carrier, time division, or frequency division is more suitable.

  FIG. 13 is a diagram illustrating a first configuration example of a reservation allocation channel which is a kind of circuit switching channel. When a terminal connects to a base station for the purpose of data communication or the like, the base station first assigns a reservation allocation channel to the terminal using a control channel. Since the reserved allocation channel is a circuit switching channel, once the terminal is connected to the reserved allocation channel, it continues to use the reserved allocation channel until communication is completed. The base station assigns one or more communication channels to the terminal for data communication between the base station and the terminal using the reservation assignment channel. However, regarding the reservation allocation channel, even if it is a circuit switching channel, it is not always necessary for the base station and the terminal to perform one-to-one communication in all frames, and one reservation allocation channel is shared by a plurality of terminals. Also good. The circuit switching channel (reserved allocation channel) shown in FIG. 13 is used for the base station to perform bidirectional communication with two terminals simultaneously using the downlink reserved data allocation area and the uplink data area. It is an example of a channel configuration.

  In the reserved allocation data area in the downlink channel of FIG. 13B, the base station sends the channel number (channel candidate) to be used in the next channel allocation section to the terminal. In this channel configuration, when one or more reservation allocation channels are shared by three or more terminals, the terminal number is transmitted together with the channel number in the reservation allocation data area to determine which terminal the information is addressed to. Can be easily distinguished. In the reservation allocation data area, transmission power control information, transmission timing control information, ACK / NACK information, modulation / coding information, and other control information may be used simultaneously. Further, in the uplink data area of FIG. 13A corresponding to the reservation allocation data area, it may be used for transmission of control information such as ACK / NACK information, modulation / coding information, and channel allocation request.

  When sharing a reservation allocation channel with multiple terminals, it is assumed that the neighboring base stations are empty channels and the channel is not taken away. When a signal is transmitted, it is easy to be detected by a neighboring base station. At this time, if the transmission timing of the circuit-switched training signal is shifted for each terminal, or OFDM symbols and SC data blocks are cyclically shifted and transmitted, it becomes easier to separate at the base station. Alternatively, the circuit-switched training area is used only by the terminal that is the destination of the downlink reserved allocation data area among a plurality of terminals, and the other terminals use terminal-specific training signals in the BF training area. Can also be transmitted for weight calculation for beamforming.

  FIG. 14 is a diagram illustrating a second configuration example of the reservation allocation channel. In the configuration of FIG. 14, in addition to the first configuration example of FIG. 13, there is a random access region in the uplink channel of FIG. Such a configuration is effective when one reservation allocation channel is shared by more terminals. The random access area is an area for a terminal to transmit a communication channel allocation request when a reservation allocation channel is allocated but there is no authority to transmit in the uplink data area.

  Hereinafter, the priority of the training signal will be described. Priorities are set for a plurality of training signals used for each communication channel. As already described, there are roughly three types of training signals. They are a circuit-switched training signal for indicating that a circuit-switched channel is used, a BF training signal for calculating the beamforming weight, and a packet-switched training signal for determining the right to use the packet-switched channel. is there.

  15 and 16 show a first configuration example of the training signal priority table (priority information). The table in FIG. 15 corresponds to the second information, and the table in FIG. 16 corresponds to the first information. As shown in FIG. 15, the training signal A1 is a circuit-switched training signal transmitted in the circuit-switched training area, and the highest priority is set for all channels. The training signal A1 corresponds to, for example, a first training signal. Training signals B1 to B16 are packet-switched training signals transmitted in the packet-switched training area, and have different priorities for each communication channel. Training signals B1 to B16 correspond to, for example, second to nth training signals. FIG. 16 shows a list of numbers of packet exchange training signals B1 to B16 that are fixedly assigned to the base stations CS1 to CS16. The BF training signal A2 is not shown here because it is not defined by itself in terms of priority. By using the priority table shown in the set of FIG. 15 and FIG. 16, the priority in each communication channel and the training signal to be used can be known for each base station. In this configuration example, the base station does not need to teach the priority of the training signal to the terminal.

  The priorities of the packet exchange training signals determined from FIGS. 15 and 16 are summarized from the viewpoint of the base station as shown in FIG. However, the order is excluding the circuit switching training signal whose priority is always first. In the example of the figure, the priority of each base station is set so as to cyclically change for each channel, and the priority of each base station is the same when averaged. However, in FIG. 17, the channel number is an odd number so that the priority of one of the training signals does not increase unilaterally when the priorities of two types of packet-switched training signals (for example, B1 and B2) are compared. The communication channel is set so as to cyclically change for each communication channel with reference to a column in which the arrangement of B1 to B16 is in the opposite direction between the communication channel and the even communication channel. 15 to FIG. 17, the priority for each base station is first set as shown in FIG. 17, and then, based on the fixed elements (in this example, FIG. 16), FIG. It is also possible to create a table.

  18 and 19 show a second configuration example of the training signal priority table (priority information). The table in FIG. 18 corresponds to the second information, and the table in FIG. 19 corresponds to the first information. As shown in FIG. 18, the priority of the training signal is fixed regardless of the channel, the circuit-switched training signal A1 is the highest, and the packet-switched training signals B1 to B16 are the priority that follows in sequence. Yes. FIG. 19 shows a list of training signal numbers B1 to B16 used by the base station in each channel. Unlike the first configuration example, the circuit switching training signals B1 to B16 are not unique to the base station. Unlike the first configuration example, in the second configuration example, the base station needs to teach the terminal of information on the training signal to be used in each base station, that is, the information of FIG. A first method for transmitting the information of FIG. 19 to the terminal is to transmit it as broadcast information in the control channel. A second method is to transmit information on a training signal to be used together with a channel number (training designation information designating a training signal to be transmitted to the base station) on the reserved allocation channel. Moreover, when the priority of the packet exchange training signal determined from FIG. 18 and FIG. 19 is summarized from the viewpoint of the base station, it becomes the same as the first configuration example shown in FIG.

  20 and 21 are diagrams illustrating a third configuration example of the training signal priority table (priority information). The table in FIG. 20 corresponds to the second information, and the table in FIG. 21 corresponds to the first information. As shown in FIG. 20, as in FIG. 15, the training signal A1 is a circuit-switched training signal transmitted in the circuit-switched training area, and the highest priority is set for all channels. Training signals B1 to B16 are packet-switched training signals transmitted in the packet-switched training area, and have different priorities for each communication channel. FIG. 21 shows a list of numbers of the packet exchange training signals B1 to B16 used by the base stations CS1 to CS16 for each communication channel. In the third configuration example, the number of the packet exchange training signal used for each base station and its priority can be changed for each communication channel. Moreover, when the priority of the packet exchange training signal determined from FIG. 20 and FIG. 21 is summarized from the viewpoint of the base station, it becomes the same as the first configuration example shown in FIG.

  When setting priorities of B1 to B16 in the first to third configuration examples of the priority table described above, the priority of each base station is uniformed on average, as shown in FIGS. 20, setting the table of FIG. 21 makes it possible for each base station to obtain the right to use the channel equally on average.

  Alternatively, a plurality of tables shown in FIGS. 15, 19, 20, and 21 may be prepared, and the plurality of tables may be selectively used periodically with time. Thus, by using a plurality of tables, the priority level of a specific channel can be changed with time.

  Alternatively, the base station may change the tables in FIGS. 15, 19, 20, and 21 according to the increase or decrease in the number of terminals in the cell and the bandwidth request (increase or decrease in the number of necessary communication channels). , The base station control device 11 requests the base station control device 11 to temporarily change the priority so that the overall priority becomes higher or lower. 21. By using the method of changing the table of FIG. 21 and transmitting the changed new table to a plurality of base stations including this base station, a more flexible system design becomes possible.

  FIG. 22 is a diagram illustrating an example of a list of training signal numbers used in each training signal region in each frame in the channel allocation section. In this example, four frames are one channel allocation section. If it is necessary to transmit the packet-switched training signals B1 to B16 as the entire system within the channel allocation section, it is preferable to divide B1 to B16 into four frames and transmit four training signals for each frame. In this way, by dividing the number of frames in the channel allocation section, the number of training signals transmitted for each frame can be limited. As a result, the overhead required for the training signals can be reduced as a whole system. It becomes possible.

  In particular, in the case of setting the priority of the training signal as shown in FIG. 18, by assigning to the frame as shown in FIG. 22, the packet exchange training signal is transmitted for each frame in descending order of priority. Therefore, it is not necessary to detect a training signal in a subsequent frame when a training signal having a priority higher than that of the base station itself is detected.

  FIG. 23 is a diagram illustrating a first configuration example of a reservation section defined as a section in which a base station can transmit a reservation allocation channel in order to allocate a communication channel to a terminal in the channel allocation section. A section in which a reserved allocation channel for channel allocation section k can be transmitted is defined as a reserved section. That is, a reservation allocation channel is transmitted from the base station in the downlink of any frame in the reservation interval k, and the terminal transmits the frame determined by the priority table and the table in FIG. 22 in the reservation allocation interval k-1. In the uplink, a packet-switched training signal is transmitted. The base station determines whether to actually assign the channel assignment interval k to the terminal by comparing the priority of the training signal from the terminal in the neighboring base station with the priority of the packet exchange training signal transmitted to the terminal.

  In the configuration example of FIG. 23, the channel assignment interval k-1 and the reservation interval k are synchronized. Since the terminal transmits the packet exchange training signal after receiving the reservation assignment channel, for example, when the base station transmits the reservation assignment channel in the second frame of the reservation interval k, the packet exchange is performed. The training signal can be transmitted only in the second to fourth frames in the reservation allocation section k-1. That is, when a communication channel is assigned a packet exchange training signal belonging to the packet exchange training area of the first frame according to the priority table, this means that this communication channel cannot be assigned. Therefore, in the first configuration example of the priority table, since the base station always uses the same packet exchange training signal (area), there is a difference in the number of communication channels that can be used from the beginning depending on the base station. It is not suitable for use with the first configuration example of the reserved section shown. Accordingly, it is appropriate to use the first configuration example of the reserved section together with the second configuration example or the third configuration example of the priority table.

  FIG. 24 is a diagram illustrating a second configuration example of a reservation section defined as a section in which a base station can transmit a reservation allocation channel in order to allocate a communication channel to a terminal in the channel allocation section. This second configuration example is a configuration suitable for use in combination with the first configuration example of the priority table, which has a problem in the case of FIG. FIG. 24 shows a configuration example in the case where the priority table is the first configuration example and the packet exchange training signal is fixedly assigned to the second frame in the channel assignment section. The reserved section is configured every four frames so that a frame (second frame) to which a packet exchange training signal is assigned becomes the last frame. This is because the base station transmits a packet-switched training signal on the uplink of the second frame of the channel assignment section k-1 to the terminal, and sets the reserved assignment channel in any of the four frames before it. This is for sending.

  The operation for the base station to allocate a communication channel in the terminal as a packet switching channel using the reservation allocation channel will be described below.

  FIG. 25 is a flowchart showing a packet-switched channel assignment procedure in the base station in the cellular radio communication system according to the present embodiment. FIG. 25 shows a procedure for the base station to allocate a communication channel (packet switched channel) to a terminal in the channel allocation section k. In the following description, for the sake of simplicity, the description is made according to the first configuration example of the reserved section. However, in the flowchart of FIG. The description includes the case where the channel assignment sections k-2 overlap.

  The base station starts detecting a circuit-switched training signal from the uplink of the start frame of the channel assignment section k-2 (S11). When a circuit switching training signal is detected (NO in S11), the communication channel from which this circuit switching training signal is detected is being used as a circuit switching channel by another base station, and even in the channel assignment section k. It is determined that it will continue to be used, and it is abandoned to allocate this communication channel to the terminal in the channel allocation section k (S20). These series of operations are repeated until the channel assignment interval k-2 ends.

  The reason for detecting the circuit switching training signal in the channel allocation section k-2 instead of the channel allocation section k-1 is that when the communication channel is already used as a circuit switching channel, in the channel allocation section k-1, This is to avoid such a situation because transmission of a packet-switched training signal will cause interference to the circuit-switched channel. However, considering the possibility that the use of the circuit-switched channel ends in channel assignment section k-2, only the uplink of the final frame in channel assignment section k-2 is observed to detect the circuit-switched training signal. It is actually possible to determine whether or not.

  If no circuit-switched training signal is detected in the channel assignment section k-2, the base station transmits a reservation assignment channel in any frame of the reservation section k and tries to assign it to the terminal. An instruction is transmitted to transmit a packet exchange training signal in a predetermined packet exchange training area of a communication channel (channel candidate) (S12 to S16). Before and after transmission of the reserved allocation channel, the base station detects training signals (circuit-switched training signals and packet-switched training signals) transmitted in each training region in each uplink of the channel allocation section k-1. (YES in S16, S17). Then, referring to the priority table, if a training signal having a priority higher than the priority of the packet exchange training signal transmitted from the terminal to itself is detected (NO in S17), the channel allocation section The assignment of this communication channel to the terminal is stopped at k (S20).

  If a training signal having a priority higher than the priority of the base station itself is not detected at the end of the channel assignment section k-1, communication in the channel assignment section k is performed (YES in S17, YES in S18). It is determined that the right to use the channel has been acquired, and this communication channel is actually allocated to the terminal (S20).

  When the channel assignment section is composed of N frames (N is an integer of 2 or more), the base station actually transmits the channel assignment section after the terminal transmits a packet switching training signal in the channel assignment section k-1. There is a time gap of at most N-1 frames before a channel is allocated to a terminal at k. For this reason, when the weight of the downlink beamforming in the first frame of the channel assignment section k is calculated on the basis of the training signal transmitted in the uplink of the channel assignment section k−1, at most N−1 pieces There is a delay of frames. For this reason, when the moving speed of the terminal is high, the communication path has already fluctuated, so that beam forming with very inaccuracy occurs and reception SINR is lowered.

  FIG. 26 is a flowchart showing a training signal transmission method in the channel assignment section k-1 for solving the above problem.

  In this method, when a packet switching training signal is transmitted to a terminal other than the last frame of the channel allocation section k-1, an additional training signal that is another training signal is transmitted again in the last frame. To do. Details of the additional training signal will be described later. When the terminal is originally supposed to transmit a packet exchange training signal in the final frame (Nth frame), the method described below is not necessary.

  The basic operation of FIG. 26 is the same as that of FIG. 25 up to the (N-1) th frame. Step S18 in FIG. 25 is replaced with S31 in FIG. 26, and the condition is changed from the last frame (Nth frame) to the (N-1) th frame, and S32 to S35 are added after S31. Is only different. More specifically, the difference between S18 and S31 is that when the condition of proceeding to YES in step S18 is that the priority of the base station itself is among the detected training signals when the last frame (Nth frame) is completed. In contrast to the highest case, the condition for proceeding to YES in step S31 is the case where the base station itself has the highest priority among the detected training signals at the end of the (N-1) th frame. That is. However, in the example of FIG. 26, it is assumed that the reservation allocation channel is already transmitted in any one of the first to (N-1) th frames in S14.

  The base station transmits the reserved allocation channel to the terminal again in the final frame, and sends an instruction to the terminal to transmit an additional training signal on the uplink of the final frame (YES in S31, S32, and S33). However, when the second configuration example of the reserved section is used, the reserved section that first transmitted the reserved allocation channel is the reserved section k, but the final frame of the channel allocation section k-1 is the reserved section k + 1. Therefore, an identifier (bit or the like) for distinguishing these may be included in the reserved allocation channel. No priority is set for the additional lane signal itself. Therefore, the priority of the base station remains the priority of the packet exchange training signal used previously.

  The base station tries to detect a training signal as usual also in the uplink of the final frame (S35), and confirms whether a training signal higher than the priority of the base station itself is not detected. Only when it is not detected (YES in S35), finally, in the channel assignment section k, this communication channel is assigned to the terminal as a packet switching channel (S19).

  In this way, when the right to use the channel assignment section k is obtained by transmitting the additional training signal to the terminal in the final frame of the channel assignment section k-1, the channel assignment section is used using the additional training signal. Weight calculation for beam forming can be performed accurately even in the first frame of k.

  However, as described above, it is impossible to transmit the reserved allocation channel again in the final frame to all terminals that have transmitted the reserved allocation channel in the reserved section, in view of the amount of resources of the reserved allocation channel. Therefore, the above processing is performed only for terminals that require additional training signals, such as terminals with a fast moving speed and terminals that have a long time from when a reserved allocation channel is sent until the start of the channel allocation section. It is good to do.

  Hereinafter, a first configuration example of the additional training signal will be described. When the priority of the packet switching training signal of the base station itself is higher than at least one of the priority of the packet switching training signal that may be transmitted in the final frame of the channel allocation section k-1. , The additional training signal is transmitted to the terminal in the training area of the packet exchange training signal. However, it is assumed that a packet switching training signal having a higher priority than the packet switching training signal of the base station itself is not detected in each frame before the last frame. Since it is not necessary to set the priority of the additional training signal itself, the pattern of the additional training signal may be the same as the packet-switched training signal of the base station itself, or a pattern dedicated to the additional training signal may be prepared. . When there are a plurality of training signals for the final frame that satisfy the above-described conditions, the reception SINR of the additional training signals can be increased by transmitting the additional training signals in a plurality of training signal regions.

  For example, if the base station has a packet-switched training signal B1 in a certain communication channel and one of the packet-switched training signals that may be transmitted in the final frame is B13, the priority of B1 is higher than B13 Is high. If the packet-switched training signal B1 has already been transmitted in any of the first to third frames, the training signal B13 is likely not to be transmitted in the last frame, and the training signal B13 is not transmitted to other base stations. Since it is already a training signal that does not need to be detected in FIG. Therefore, an additional training signal is transmitted to the terminal in an area used by the training signal B13 (for example, the packet exchange training area B1). However, since the additional training signal may compete with the training signal B13, weight calculation with high accuracy may be difficult in the first configuration example of the additional training signal.

  A second configuration example of the additional training signal will be described below. FIG. 27 is a diagram illustrating a second configuration example of the packet switching channel in which an additional training signal region for the additional training signal is added to the uplink channel. In the first configuration example of the additional training signal, the existing packet switching training area is used. However, in the second configuration example, the training area for the additional training signal is added to the uplink channel as shown in FIG. Is assigned. Therefore, there is no possibility of competing with other training signals, and the base station can execute highly accurate weight calculation. The pattern of the additional training signal may be the same as the packet switching training signal of the base station itself as in the first configuration example of the additional training signal, or a pattern dedicated to the additional training signal may be prepared. The second configuration example of the packet switching channel in the second configuration example of the additional training signal is a configuration of only the Nth frame (final frame) in the channel allocation section. The first configuration example of the packet switching channel is used in the same manner as in FIG.

  In the first configuration example of the additional training signal, depending on the priority setting of the packet switching training signal, the additional training signal cannot always be transmitted in the final frame, and there is a possibility of a collision. On the other hand, in the second configuration example of the additional training signal, since an area for the additional training signal is secured, the additional training signal is transmitted without causing a collision regardless of the priority of the packet switching training signal. be able to.

  In the examples so far, an example in which a packet switching channel is allocated has been shown. However, a communication channel (packet switching channel) that has acquired the right to use is continuously used as a circuit switching data channel as well as a single channel allocation section (line The method for switching to the exchange data channel is shown below. When a packet switching channel is assigned in the channel assignment section k, the BF training signal A2 is normally used as a training signal for beamforming weight calculation in the channel assignment section k. However, since priority is not set for the BF training signal A2 itself, in the case where a right to use the channel by the packet-switched training signal occurs, in the next channel allocation section k + 1, it is sent to another base station. The right to use this communication channel may be deprived.

  In order to prevent such a situation, the base station instructs the terminal to simultaneously transmit not only the BF training signal A2 but also the circuit switching training signal A1 in the channel allocation interval k. Alternatively, when the base station receives a transfer request for requesting a transfer to a circuit-switched data channel from the terminal, the base station instructs the terminal that has sent the transfer request to transmit a circuit-switched training signal A1 in the packet-switched channel. The instruction data to be transmitted is transmitted. As a result, a higher priority is guaranteed than the packet exchange training signal transmitted in response to an instruction from another base station, so that the communication channel is deprived of neighboring base stations even in the channel allocation interval k + 1. The right to use can be maintained. However, in the channel allocation section k, it is necessary to use the packet switched data channel of FIG. 11 instead of the circuit switched data channel of FIG. 9 as the channel configuration. This is because in this channel assignment section k, there is a possibility that a packet switching training signal may be transmitted from the terminal to another base station, and interference with this packet switching training signal is prevented. Once transmission of a circuit-switched training signal is started, transmission of a packet-switched training signal in the subsequent channel allocation section can be prevented. Therefore, from the next channel allocation section k + 2, it is not a packet-switched channel. With the channel configuration shown in FIG. 9 as an exchange data channel, this communication channel can be used continuously.

  FIG. 29 is a diagram illustrating a configuration example of a base station according to the present embodiment. FIG. 30 is a diagram illustrating a configuration example of a terminal according to the present embodiment. FIG. 28 is a diagram illustrating an example of a channel assignment procedure performed between a plurality of base stations and a terminal.

  FIG. 28 shows an operation when the base station CS1 and the base station CS2 contend for the right to use a certain communication channel. Here, terminal PS1 is connected to base station CS1, and a reservation allocation channel is allocated from CS1. Similarly, terminal PS2 is connected to base station CS2, and a reservation allocation channel is allocated from CS2. Hereinafter, the procedure for allocating a channel in the channel allocation section k shown in FIG. 28 will be described together with the operations of the base station in FIG. 29 and the terminal in FIG.

  The operation of the base station in the channel assignment section k-2 will be described. In the uplink, the base station switches the transmission / reception switching unit 102 to the reception side. A signal received from the antenna 101 is converted into a baseband signal by the RF / IF receiving unit 103 and converted into a digital signal by the A / D conversion unit 104. In the training signal detection unit (detection means) 105, each communication channel Attempt to detect circuit-switched training signals. In the reserved channel determination unit (determination unit) 106, the number of the communication channel (defined as an empty channel here) for which no circuit-switching training signal has been detected, and each communication channel in the priority management unit (information holding unit) 107 Communication channel (s) to be allocated to the terminal are determined from the priority table (first information and second information). When free channels equal to or more than the number of communication channels to be allocated to the terminal are detected, if the channels are selected in descending order of priority, there is a high probability that channels can be used because they are unlikely to compete with other base stations. It is assumed that the base station already holds data to be transmitted to the terminal before determining a communication channel to be allocated to the terminal. Alternatively, it is assumed that an allocation request for requesting communication channel allocation is received from the terminal. A signal including this allocation request is received by the antenna 101, converted to a baseband signal by the RF / IF receiver 103, converted to a digital signal by the A / D converter 104, and received by a receive beamforming application unit 116 described later. The weight for each antenna is multiplied and demodulated by the data demodulator 115. The allocation request is extracted from the data obtained by demodulation. The set of the antenna 101 and the RF / IF receiver 103 includes receiving means for receiving an assignment request for requesting assignment of a communication channel from a terminal, for example.

  The operation of the base station that transmits the reserved allocation channel in the channel allocation section k-1 will be described. The number of the communication channel determined by the reserved channel determining unit 106 (candidate channel to be allocated) is data-modulated by the reserved allocation channel modulating unit 108. The reserved channel determination unit 106 notifies the channel selection unit 114 of transmission of the reserved allocation channel. The mapping unit 109 maps the modulation data to the reserved allocation channel specified by the channel selection unit 114, converts it to an analog signal by the D / A conversion unit 110, and transmits it from the antenna 101 via the RF / IF transmission unit 111. Is done. When the priority table is the second configuration example or the third configuration example, the training signal number may be sent together with the communication channel number. In the example of FIG. 28, the base station CS1 transmits the reserved allocation channel to the terminal PS1 in the second frame of the channel allocation interval k-1. Similarly, the base station CS2 transmits the reserved allocation channel in the first frame of channel allocation interval k-1. These reserved allocation channels are assumed to include the same communication channel number of interest here.

  The base station shown in FIG. 29 includes an RF / IF receiver 103 to an A / D converter 104 and a D / A converter 110 to an RF / IF transmitter 111 for each antenna for beam forming. There are multiple systems. When transmitting a reservation allocation channel, the transmission beamforming application unit 112 can apply a weight for each antenna and perform transmission, whereby a high SINR can be realized in the terminal. The weight is calculated from the uplink training signal area of the reserved allocation channel.

  The operation of the terminal that receives the reserved allocation channel in channel allocation section k-1 will be described. The terminal switches the transmission / reception switching unit 202 to the reception side. A received signal received from the antenna 201 is converted into a baseband signal by the RF / IF receiver 203 and then converted into a digital signal by the A / D converter 204. Next, from the digital signal, the reservation allocation channel demodulator (candidate information acquisition means) 205 demodulates the communication channel number (s) transmitted by being mapped to the reservation allocation channel by the base station. Next, the training signal generated in the training signal generation unit 206 is mapped to the communication channel of the demodulated communication channel number by the mapping unit 207 and converted into an analog signal by the D / A conversion unit 208, and then the RF / IF The data is transmitted from the antenna 201 via the conversion unit 209. The training signal to be used is determined using a priority table for each communication channel, for example. In this example, the base station CS1 uses the training signal B1, the base station CS2 uses the training signal B2, and the priority in this channel is higher for the training signal B1 than for B2. The demodulated communication channel number is held in the storage unit 210 for the next channel assignment section. A set of the antenna 201, the RF / IF receiving unit 203, and the training signal generating unit 206 corresponds to, for example, a training signal transmitting unit. It is assumed that the base station already holds data to be transmitted to the terminal before transmitting the reservation allocation channel including the communication channel number. Alternatively, the terminal transmits an allocation request for requesting allocation of a communication channel to the base station before receiving a reservation allocation channel including the communication channel number. That is, data including an allocation request is modulated by the data modulation unit 212, mapped to a reserved allocation channel in the uplink, for example, by the mapping unit 207, converted to an analog signal by the D / A conversion unit 208, and then the RF / IF conversion unit The data is transmitted from the antenna 201 via 209.

  The operation of the base station at the time of detecting the packet exchange training signal in the channel assignment section k-1 will be described. The base station tries to detect the packet-switched training signal in the training signal detection unit 105 including the training signal transmitted not only to the base station itself but also to the neighboring base stations. That is, the base station CS1 tries to detect a training signal transmitted from the terminal PS2 as well as the terminal PS1. However, the base station CS1 does not need to know the presence of the terminal PS2 in advance. In this example, from the first frame to the third frame, the base stations CS1 and CS2 both detect the training signals B1 and B2. The base station CS2 detects that the training signal B1 has a higher priority than B2 at the end of the third frame in the channel selection unit (allocation means) 114. As a result, the channel selection unit 114 in the base station CS2 gives up the communication channel assignment.

  The operations of the base station and the terminal in the fourth frame in the channel assignment section k-1 will be described. In the downlink of the fourth frame, the base station CS1 transmits the reservation allocation channel again to the terminal PS1, and instructs the terminal PS1 to transmit an additional training signal on this communication channel.

The terminal PS1 that has received the reservation allocation channel transmits an additional training signal in the uplink of the fourth frame in accordance with the instruction. In the fourth frame, the base station CS1 determines that a training signal having a higher priority than the training signal B1 has not been detected in the channel selection unit 114, and grants the right to use this communication channel in the channel allocation section k. Determine that the base station CS1 has acquired. That is, channel selection section 114 allocates this communication channel to terminal PS1 in channel allocation section k.
Since the operation of the base station and the terminal in the fourth frame is only an auxiliary operation for calculating the beamforming weight of the first frame in the channel allocation interval k, the base station may not apply beamforming or This is a process that is not necessarily required when the terminal moves slowly and when the terminal originally transmits the training signal B1 in the fourth frame.

  The operation of the base station and the terminal in the downlink of the channel assignment section k will be described. In the base station CS1, data for transmission in the data area of the communication channel is modulated by the data modulation unit 113, and data of the communication channel (packet switching channel) determined to be used in the channel allocation section k-1 by the mapping unit 109. It is mapped to the area, and transmitted from the antenna 101 through the processing in the D / A conversion unit 110 and the RF / IF unit 111 in the same manner as described above. At this time, weight calculation is performed using the BF training signal A2, and transmission is performed after the beamforming is applied by the transmission beamforming application unit 112. At this time, for the next channel allocation section k + 1, in the reserved allocation channel, the channel numbers modulated by the reserved allocation channel modulator 108 are multiplexed and transmitted simultaneously if necessary. However, for the weight calculation in the first frame, an additional training signal or a packet exchange training signal received in the reserved section is used. When an additional training signal is not used, stable downlink communication can be realized by setting a modulation / coding rate such that the data rate of the first frame is lower than that of other frames. Even if an additional training signal is used, if the weight calculation accuracy may not be so good as in the first configuration example of the additional training signal, the data rate of the first frame is compared with other frames. Stable downlink communication can be realized by setting the modulation / coding rate to be low.

  In terminal PS1, in the communication channel of the number held in storage unit 210 in channel allocation section k-1, data demodulator 211 demodulates the data area of the packet-switched channel transmitted from base station CS1. At this time, it is assumed that the base station CS1 notifies the terminal PS1 of the number of the communication channel actually allocated in the channel allocation section k using the reserved allocation channel. Alternatively, without using the reservation allocation channel, the terminal checks whether the communication channel is actually allocated to itself. As a method, in the communication channel transmitted from the base station in the first frame, the terminal number of PS1 is described at the head of the data area of the communication channel, so that the terminal confirms whether the communication channel is actually allocated to itself. can do. If serial numbers for a plurality of communication channels actually assigned to the terminal are added to the data area in the order of the communication channel numbers, the terminal can detect when it fails to detect its own communication channel. Will be able to be easily recognized. As described above, the terminal includes notification acquisition means for acquiring notification of the communication channel assigned by the base station from the base station. The notification acquisition means is included in, for example, the reservation allocation channel demodulation unit 205.

  Operations of the base station and the terminal in the uplink of the channel assignment section k will be described. In terminal PS1, data to be transmitted is modulated by data modulation section 212, mapped to the data area of the communication channel (packet switching channel) by mapping section 207, and transmitted from antenna 201 through the same method as described above. At that time, the BF training signal A2 is also transmitted for calculating the beamforming weight at the base station. Also, if you want to use this communication channel as a circuit switching channel for a long time instead of as a packet switching channel, not only the BF training signal A2 but also a circuit switching training signal is transmitted with the packet switching channel configuration. . In the subsequent channel assignment section, when the circuit switching channel is used, the configuration of the circuit switching channel is used.

  In the base station CS1, the data demodulated in the data demodulator 115 is demodulated from the signal converted into the digital signal in the A / D converter 104. Here, before the data demodulation in the data demodulation unit 115, the reception beamforming application unit 116 applies a weight for each antenna to receive, thereby realizing a high SINR. The weight is calculated from the BF training signal A2 transmitted from the terminal.

  A reference for detecting the training signal in the training signal detection unit 105 of the base station will be described below. The first training signal detection method in the training signal detection unit 105 calculates the correlation value with the training signal for the digital signal output from the A / D conversion unit 104, and the magnitude (power) of the correlation value. Is equal to or greater than the threshold, it is determined that a training signal has been detected. Since the training signal to be received has a reception timing shift, when calculating the correlation value, the component of the signal component whose timing is shifted is also calculated, and the total of them is calculated. In the OFDM scheme and SC scheme, the same correlation value can be calculated on the frequency axis by performing Fourier transform processing (FFT processing) on the digital signal. In this case, the timing shift on the time axis causes phase rotation on the frequency axis, and therefore, when multiplying the training signal, the correlation value is calculated by taking phase rotation into account.

  The second training signal detection method in the training signal detection unit 105 is the power of the subcarrier (frequency component) in which the training signal exists with respect to the signal obtained by subjecting the digital signal output from the A / D conversion unit 104 to Fourier transform processing. If the total power is equal to or greater than the threshold, it is determined that a training signal has been detected. This method is a simple means that can be applied when the training signal region is allocated separately for each subcarrier (frequency component) as shown in FIGS. Furthermore, in this detection method, since it is not necessary to know the pattern of the training signal transmitted in the training area, each base station may use a unique scrambling pattern on the training signal. . The effect of multiplying such a scrambling pattern is that even when training signals used by other base stations are transmitted simultaneously in the same training area, when detecting the correlation of the desired training signal, The influence of interference from other training signals can be averaged.

  The third training signal detection method in the training signal detection unit 105 includes the power of each training signal (correlation value or total power) calculated by the first or second detection method and the training signal of the base station itself. When the ratio with the power (correlation value or total power) is equal to or greater than the threshold value, it is determined that each training signal has been detected.

  As a threshold value setting method in the first to third training signal detection methods described above, a constant threshold value is used regardless of the training signal. As another threshold value setting method, the threshold value is lowered as the priority of the training signal is higher. This is because the higher the priority of the training signal, the higher the detection probability. As another threshold value setting method, the threshold value is set lower as the priority difference between the training signal of the base station itself and the training signal to be detected is larger. This is because, as in the previous setting method, the higher the training signal priority is, the higher the detection probability is. In this case, instead of absolute priority, relative priority is used. Based on the difference.

  As shown in FIG. 29, the base station manages the priority for each training signal (each base station) of each communication channel in the priority management unit 107. Under normal conditions, the priority of the training signal is set to be almost the same for all base stations when the communication channel is averaged. However, the base stations with dense terminals have more priority than the surrounding base stations. Communication channels may be required. In such a situation, the base station transmits a request for updating the priority table to increase the overall priority of the base station to the base station controller 11 connected through the wired network. . The base station control device 11 receives such a request, changes the priority table according to the request if possible, and notifies a plurality of connected base stations. In this way, a flexible system configuration can be realized by changing the priority table according to the request for each base station.

  A first method for changing the priority of the base station packet-switched training signal is described below. FIG. 31 is a diagram illustrating an example of a priority table in which the priority of the base station CS1 is set high by changing FIG. In the example of FIG. 31, the priority of the packet exchange training signal B1 used by the base station CS1 is changed to a setting that always becomes one of priority 2 to priority 5 (A1 is always priority 1). ). As a result, the priorities of the other packet-switched training signals are gradually lowered as compared with FIG. The priority of the packet exchange training signal determined from FIG. 31 and FIG. It can be seen that the priority of the base station CS1 is set higher on average than in the case of FIG. Thus, the priority of a specific base station can be changed by rewriting the priority table. It is obvious that the same method can be applied not only to the first configuration example of the priority table but also to the second to third configuration examples.

  A second method for changing the priority of the packet exchange training signal of the base station will be described below. In the examples so far, the case where the maximum number of multiplexed base stations (for example, the number of control channels in FIG. 4) and the number of packet exchange training regions in the channel assignment section are equal to 16 has been described as an example. In the second method, by setting a larger number of packet switching training areas in advance than the maximum multiplexing number of base stations, the remaining packet switching training areas are allocated to the base station whose priority is to be increased, Increase the priority of a specific base station. For example, it is assumed that the maximum number of multiplexed base stations is 15, not 16, and the packet-switched training signal area corresponding to CS9 is not used by any base station without permission (that is, there is no base station CS9). At this time, the priority management unit permits the base station, for example, CS1, to increase the priority to use the packet switching training signal corresponding to CS9, so that CS1 can switch two packets in a certain communication channel. Training signals (eg, B1 and B9) can be used. At this time, the base station always uses the higher priority of B1 and B9 in the priority table, thereby making it easier to obtain the right to use the communication channel. For example, if the priority of the packet exchange training signal of the base station as shown in FIG. 17 is as shown in FIG. 33, the base station CS1 has not only CS1 but also a priority corresponding to CS9 at the same time. Therefore, in FIG. 33, the higher priority is given to CS1 and CS9. That is, the base station CS1 uses the CS1 packet exchange training signal in the communication channels TCH (1) to TCH (8), and uses the CS9 packet exchange training signal in the TCH (9) to TCH (16). Become.

  In the first method of changing the priority, the priority management unit needs to transmit the information of the changed priority table to the entire surrounding base stations via the base station controller 11. On the other hand, in the second method, since only the assignment of a specific packet switching training signal (area) is changed, there is no need to change the priority table itself, and the priority management unit does not need to change the specific packet switching training signal. The change information only needs to be transmitted to the base station related to the change of the allocation of the signal (in the above example, B9 which is a training signal corresponding to CS9).

  Up to this point, the circuit-switched channel allocation unit and the packet-switched channel allocation unit have been made equal to one communication channel. However, the overhead required for the training area can be further reduced by using a plurality of communication channels as packet switching channel allocation units. For example, it is assumed that two communication channels connected in the frequency direction are defined as a super channel, and a packet switching channel allocation unit is allocated and used in super channel units.

  FIG. 34 is a diagram illustrating a frame configuration example in the case where two communication channels (TCH) in FIG. 2 are one super channel (STCH). For example, STCH (1) is obtained by connecting TCH (1) and TCH (5) in FIG. In the case of using a packet switching channel, it is considered that the allocation in STCH units shown in FIG. 34 is performed, and that the circuit switching channel is allocated in TCH units in FIG. In such a case, if the number of packet switching training areas per packet switching channel and the number of subcarriers per packet switching training area are kept the same as in FIG. 11, the ratio of the packet switching training area to the packet switching channel Can be halved. Similarly, if the ratio of the packet switching training area to the packet switching channel is kept the same, the number of packet switching training areas in the packet switching channel can be doubled, so that the length of the channel allocation section can be halved.

  FIG. 35 is a diagram showing a channel allocation procedure for packet-switched channels in units of super channels. Here, two circuit switched channels are equal to the size of one packet switched channel. The difference from the flowchart of FIG. 25 is that it is tested whether a circuit-switched training signal is detected in two communication channels (TCH) instead of one communication channel in the channel assignment section k-2 (S41). ). The other steps in FIG. 35 are essentially the same as those in FIG. 25, and therefore steps that are substantially the same as those in FIG.

  As described above, according to the present embodiment, it is not necessary to directly share channel allocation information between base stations, and the priority table and a plurality of types of training signals are used. Therefore, it is possible to allocate channels flexibly in units of several frames while avoiding collision of channel usage between base stations, and to efficiently handle both circuit-switched traffic and packet-switched traffic. Can do.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The figure which shows the structural example of the cellular radio | wireless communications system by this Embodiment. The figure which shows the example of a flame | frame structure of the cellular radio | wireless communications system by this Embodiment. The figure which shows the structural example of the super-frame of the cellular radio | wireless communications system by this Embodiment. The figure which shows an example of the list of the numbers of the control channel which a base station uses in the cellular radio | wireless communications system by this Embodiment. The figure which shows the structural example of the control channel and communication channel in the cellular radio | wireless communications system by this Embodiment. The figure which shows the classification | category of the communication channel in the cellular radio | wireless communications system by this Embodiment. The figure which shows the 1st structural example of the channel allocation area in the cellular radio | wireless communications system by this Embodiment. The figure which shows the 2nd structural example of the channel allocation area in the cellular radio | wireless communications system by this Embodiment. The figure which shows the structural example of the circuit switching channel in the cellular radio | wireless communications system by this Embodiment. The figure which shows an example of a structural example of the circuit switching training area | region and BF training area | region in the cellular radio | wireless communications system by this Embodiment. The figure which shows the 1st structural example of the packet switching channel in the cellular radio | wireless communications system by this Embodiment. The figure which shows the structural example of the packet exchange training signal area | region in the cellular radio | wireless communications system by this Embodiment. It is a figure which shows the 1st structural example of the reservation allocation channel in the cellular radio | wireless communications system by this Embodiment. The figure which shows the 2nd structural example of the reservation allocation channel in the cellular radio | wireless communications system by this Embodiment. The figure which shows the 1st structural example of the priority table of a training signal in the cellular radio | wireless communications system by this Embodiment. The figure which shows the list of the number of the training signal which a base station uses in the 1st structural example of the priority table of a training signal in the cellular radio | wireless communications system by this Embodiment. The figure which summarized the priority of the packet exchange training signal in the cellular radio | wireless communications system by this Embodiment from a viewpoint of a base station. The figure which shows the 2nd structural example of the priority table of a training signal in the cellular radio | wireless communications system by this Embodiment. The figure which shows the list of the number of the training signal which a base station uses in the 2nd structural example of the priority table of a training signal in the cellular radio | wireless communications system by this Embodiment. The figure which shows the 3rd structural example of the priority table of a training signal in the cellular radio | wireless communications system by this Embodiment. The figure which shows the list of the number of the training signal which a base station uses in the 3rd structural example of the priority table of a training signal in the cellular radio | wireless communications system by this Embodiment. The figure which shows an example of the list of the frames which transmit the training signal in the channel allocation area in the cellular radio | wireless communications system by this Embodiment. The figure which shows the 1st structural example of the reservation area in the cellular radio | wireless communications system by this Embodiment. The figure which shows the 2nd structural example of the reservation area in the cellular radio | wireless communications system by this Embodiment. The flowchart which shows the packet switching channel allocation procedure in the base station in the cellular radio | wireless communications system by this Embodiment. The figure shown about the transmission method of the BF training signal in the cellular radio | wireless communications system by this Embodiment. The figure which shows the 2nd structural example of the packet switching channel in the cellular radio | wireless communications system by this Embodiment. The figure which shows an example of the channel allocation procedure between the base station and a terminal in the cellular radio | wireless communications system by this Embodiment. The figure which shows the structural example of the base station in the cellular radio | wireless communications system by this Embodiment. The figure which shows the structural example of the terminal in the cellular radio | wireless communications system by this Embodiment. The figure which shows an example of the table of the priority which changed the priority in the cellular radio | wireless communications system by this Embodiment. The figure which shows an example of the priority of the base station by the table of the changed priority in the cellular radio | wireless communications system by this Embodiment. The figure which shows an example of the priority of the base station by the table of priority in the cellular radio | wireless communications system by this Embodiment. It is a figure which shows the example of a frame structure at the time of applying a super channel in the cellular radio | wireless communications system by this Embodiment. The flowchart which shows the allocation procedure of the packet exchange channel in the super channel in the base station in the cellular radio | wireless communications system by this Embodiment.

Claims (20)

A base station that performs communication by allocating at least one communication channel among a plurality of communication channels to a terminal in a communication area, and is arranged so that the communication area partially overlaps with another base station,
Determining means for determining a communication channel candidate to be allocated to an allocation target terminal, which is a terminal in the communication area, from among the plurality of communication channels;
First information in which the x-th training signal different from the other base stations to be used among the first to n-th training signals defined in advance is determined in each of the plurality of communication channels, and the plurality of communications Information holding means for holding second information defining priority of the first to n-th training signals in each of the channels;
Instruction means for sending instruction data to instruct the allocation target terminal to transmit the x-th training signal determined by the first information in the candidate communication channel;
Detecting means for detecting a training signal transmitted from a terminal in the communication area in the communication channel candidate;
Allocating means for allocating the communication channel candidate determined by the determining means to the allocation target terminal when a training signal having a higher priority than the x-th training signal is not detected in the communication channel candidates;
Base station equipped with. The second information sets the priority for the first training signal higher than the second to n-th training signals in all of the plurality of communication channels,
The determination unit detects the first training signal in the plurality of communication channels using the detection unit, and determines the communication channel candidate from the communication channels in which the first training signal is not detected. ,
The base station according to claim 1.   The determining means preferentially selects a communication channel in which a priority of the x-th training signal is set higher than other training signals among communication channels in which the first training signal is not detected. The base station according to claim 2, wherein the base station is selected as a candidate. The instructing unit is configured to assign the packet switching channel assigned by the allocating unit to the allocation target terminal that has been allocated by the allocating unit to the packet switched channel applied to the packet switched communication as the communication channel. Transmitting instruction data instructing to transmit the first training signal;
The allocating means uses the same communication channel as the packet switched channel for the allocation target terminal that has transmitted the first training signal, and is applied to circuit switched communication after the packet switched channel ends. The base station according to claim 2 or 3, wherein the base station is continuously assigned. The first training signal is always transmitted in the circuit switched channel from a terminal assigned a circuit switched channel applied to circuit switched communication as the communication channel;
The determination means allocates to the allocation target terminal from among the super channels in which the first training signal is not detected in all communication channels in a packet switching channel having a super channel form in which a plurality of the communication channels are connected. Determine the candidate for the super channel
The assigning means is determined by the determining means when a training signal having a higher priority than the x-th training signal in the super channel candidate is not detected in all communication channels in the super channel candidate. 5. The base station according to claim 2, wherein a super channel candidate is allocated to the allocation target terminal. The communication channel is assigned in units of channel assignment sections having consecutive N frames including the plurality of communication channels,
The determination means detects the detection of the training signal transmitted from a terminal in the communication area for the plurality of communication channels in a channel allocation section immediately before a channel allocation section to be allocated to the allocation target terminal. Selecting a communication channel candidate from among communication channels in which a training signal having a higher priority than the x-th training signal is not detected at the time of determination,
The instruction means sends instruction data for instructing to transmit the x-th training signal in the communication channel candidate in the previous channel allocation section to the allocation target terminal;
The base station according to any one of claims 1 to 5, wherein   The instruction means determines that the priority of the training signal detected by the detection means in the communication channel candidates from the first frame to the (N-1) th frame in the previous channel allocation section is the x-th training. When all of the signals are lower than the priority of the signal, instruction data instructing to transmit the same or different training signal as the x-th training signal to the allocation target terminal in the communication channel candidate in the Nth frame is sent. The base station according to claim 6. The first information defines any one of the first to n-th training signals in common for all the plurality of communication channels for each base station,
The second information respectively defines different priorities for the first to n-th training signals for each of the plurality of communication channels.
The base station according to claim 1, wherein the base station is a base station. The first information defines different training signals for each base station in each of the plurality of communication channels,
The second information sets the same priority for the first to n-th training signals in all of the plurality of communication channels.
The base station according to claim 1, wherein the base station is a base station. The first information defines different training signals for each base station in each of the plurality of communication channels,
The second information defines different priorities for the first to n-th training signals for each of the plurality of communication channels.
The base station according to claim 1, wherein the base station is a base station. A base station that controls the base station to change at least one of the first information and the second information held by the information holding means according to an increase or decrease in the total number of communication channels required for each terminal in the communication area Change request means for requesting the control device via a network;
Updating means for updating the information holding means based on at least one of the changed first and second information notified from the base station control device;
The base station according to claim 1, further comprising:   The detecting means calculates a first correlation value between a signal transmitted by the communication channel candidate and data of a y-th (arbitrary value from 1 to n) training signal given in advance, and The base station according to any one of claims 1 to 11, wherein the base station determines that the y-th training signal is detected when one correlation value satisfies a threshold value.   The detection means calculates a second correlation value between the x-th training signal and the x-th training signal transmitted by the communication channel candidate, and calculates the second correlation value and the first correlation value. The base station of claim 12, wherein the base station determines that the y-th training signal is detected when a ratio satisfies a threshold.   The detection means calculates a first total power of subcarriers to which a training signal different from the x-th training signal can be mapped in the communication channel candidate, and when the first total power is equal to or greater than a threshold, 12. The base station according to claim 1, wherein it is determined that a training signal that can be mapped to a carrier is detected.   The detecting means calculates a second total power of a subcarrier to which the xth training signal is mapped, and when the ratio between the first total power and the second total power satisfies a threshold, The base station according to claim 14, wherein it is determined that a training signal that can be mapped has been detected. A wireless terminal that communicates by using at least one communication channel assigned from one of a plurality of communication channels and one of base stations arranged so that communication areas overlap each other,
Candidate information acquisition means for acquiring candidate information indicating communication channels that are candidates for allocation from a base station that is one of the base stations;
Training signal transmitting means for transmitting a training signal predetermined for each base station in each of the plurality of communication channels to the certain base station in a communication channel candidate indicated by the candidate information acquired by the candidate information acquiring means When,
Notification acquisition means for acquiring a notification of a communication channel assigned by the certain base station from the certain base station;
Wireless terminal equipped with.   The said training signal transmission means transmits the training signal for the said certain base station defined in common to all of these communication channels irrespective of the said communication channel candidate, It is characterized by the above-mentioned. The wireless terminal described.   The training signal transmitting means holds information in which a certain training signal is determined for the certain base station for each of the plurality of communication channels, and a training signal determined from the information corresponding to the candidate communication channel The wireless terminal according to claim 16, wherein the wireless terminal transmits to the certain base station. The candidate information includes training designation information that designates a training signal to be transmitted to the certain base station,
The wireless terminal according to claim 16, wherein the training signal transmitting means transmits a training signal indicated by the training designation information to the certain base station. A wireless communication method for selecting and assigning to a terminal a communication channel for communicating with one of base stations arranged so that communication areas overlap each other,
A communication channel candidate to be allocated to an allocation target terminal that is a terminal belonging to a base station that is one of the base stations is determined from the plurality of communication channels;
A training signal predetermined for each base station in each of the plurality of communication channels is transmitted from the allocation target terminal to the certain base station in the communication channel candidates,
Detecting a training signal transmitted from a terminal in a communication area of the certain base station in the communication channel candidate;
Based on the priority of each of the plurality of training signals predetermined for each of the plurality of communication channels, a training signal having a higher priority than the training signal transmitted from the allocation target terminal is detected in the communication channel candidates. If not, assign the communication channel candidate to the allocation target terminal,
Wireless communication method.

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