JP5198512B2 - Radio communication system, radio base station apparatus, and radio terminal - Google Patents

Description

  Embodiments described herein relate generally to a radio base station apparatus, a baseband apparatus, and a radio terminal that form a communication area using, for example, a microcell system.

  The PHS (Personal Handy-phone System) system uses microcells, so the cell radius (area in which wireless base stations can communicate) is smaller than that of macrocells, and handover is necessary for communications involving movement. I wo n’t. However, if the terminal moving at a high speed due to the small cell radius cannot be handed over at a high speed, the communication is disconnected. In response to this problem, a proposal has been made to perform high-speed handover by predicting the handover destination from the handover history of the terminal (communication time between the handover destination radio base station and the radio base station) and the estimated moving speed of the terminal. However, if the prediction is incorrect, a fast handover cannot be realized. Therefore, a method for selecting the size of the radio zone to be allocated from the moving speed of the terminal in a multiple radio zone environment has been proposed (see, for example, Patent Document 1).

JP-A-9-261723

  As described above, the method of predicting the handover destination from the terminal handover history and the moving speed of the terminal has a problem that a high-speed handover cannot be realized if the prediction is incorrect. On the other hand, in the method disclosed in Patent Document 1, when a multiple wireless zone environment is constructed, the cost burden is large, and when there are many terminals with high moving speeds, usable radio resources are reduced. There's a problem.

  The present embodiment has been made by paying attention to the above circumstances, and an object thereof is to provide a radio base station apparatus, a baseband apparatus, and a radio terminal that realize effective use of radio resources and improvement of communication quality. There is.

  A radio base station apparatus according to the present embodiment includes a plurality of radio units that individually form radio cells that perform radio communication with radio terminals, and a radio control unit connected to the radio units via a transmission path. In the radio base station apparatus, the radio control unit includes a first identifier that is uniquely set for each radio unit, and a second identifier that is commonly set for any combination of the plurality of radio units. An identifier generation unit that generates a radio resource that allocates a radio resource that can be used in the radio communication to the first identifier and the second identifier, and the first identifier and the second identifier A control data transmitting unit that transmits the control data to the radio unit, wherein the radio unit receives the control data via the transmission path, and the control received by the control data receiving unit. Wireless communication of data To a transmission unit that transmits more to the wireless terminal.

  The baseband device according to the present embodiment is a baseband device that is connected by a transmission path to a plurality of radio units that individually form radio cells that perform radio communication with a radio terminal, the radio unit An identifier generating unit that generates a first identifier that is uniquely set for each and a second identifier that is commonly set for any combination of the plurality of radio units; the first identifier and the second identifier And a control data transmission unit for transmitting the control data including the first identifier and the second identifier to the radio unit. To do.

  Further, the radio terminal according to the present embodiment performs radio communication via a radio base station apparatus including a plurality of radio units that individually form radio cells and a radio control unit connected to the radio unit via a transmission path. Control data including a first identifier that is uniquely set for each radio unit and a second identifier that is commonly set for any combination of the plurality of radio units is a radio terminal. And a control data receiving unit that receives the data via an ID, and an identifier selecting unit that selects an identifier to be used for the wireless communication among the first identifier and the second identifier included in the control data.

1 is an overall configuration diagram showing an embodiment of a wireless system according to the present embodiment. The functional block diagram which shows the structure of this radio | wireless communications system. The figure which shows the operation | movement by which a real radio | wireless identifier is alert | reported from a radio | wireless part to a radio | wireless terminal. The figure which shows the operation | movement by which a virtual radio | wireless identifier is alert | reported from a radio | wireless part to a radio | wireless terminal. The figure which shows the operation | movement which a wireless terminal recognizes a real wireless identifier. The figure which shows the operation | movement which a wireless terminal recognizes a virtual wireless identifier. The figure which shows operation | movement of a radio base station apparatus. The figure which shows the specific example of a real wireless identifier and a virtual wireless identifier. The figure which shows a radio | wireless resource allocation process. The figure which shows the operation | movement which a radio | wireless terminal detects a radio | wireless identifier. The figure which shows the operation | movement which a radio | wireless terminal selects a real radio | wireless identifier. The figure which shows the operation | movement which a wireless terminal selects a virtual wireless identifier.

Hereinafter, a radio base station apparatus, a baseband apparatus, and a radio terminal according to the present embodiment will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram showing an embodiment of a wireless communication system according to this embodiment. In FIG. 1, an IP (Internet Protocol) network 300 and a public switched telephone network (PSTN) network 400 are connected to a gateway device 200, and a radio base station device S is connected. The radio control apparatus S includes a radio control unit (BBU: Base Band Unit) 1 and a plurality of radio units (RRU: Remote Radio Unit) 21 to 2n. The wireless control unit 1 is connected to a plurality of wireless units 21 to 2n (generically referred to as a wireless unit 2) that individually form wireless cells that transmit and receive wirelessly, and performs wireless signal processing and signal distribution. I do. A plurality of wireless terminals PS1 to PSm (collectively referred to as wireless terminals PS) perform voice or data communication with the wireless units 21 to 2n.

  FIG. 2 is a block diagram showing the configuration of this wireless communication system. The radio terminal PS transmits user data to and from the radio unit 2 with the control data transmitting unit 101 and the control data receiving unit 102 for transmitting and receiving control data to and from the radio unit 2. A transmission unit 103 and a user data reception unit 104 are provided. The control data is data for controlling the wireless section, and the user is usually not aware of these data. The user data is data that the user transmits or receives through the wireless terminal PS. In addition to these units, the radio terminal PS includes a radio identifier selection unit 105 that arbitrarily selects from all the radio identifiers detected by the radio terminal PS and determines the radio unit 2 as a communication destination. Details of the wireless identifier will be described later.

  The wireless unit 2 transmits and receives data wirelessly between the wireless terminal PS1 and the wired data transmitting unit 201 and the wired data receiving unit 202 for transmitting and receiving data to and from the wireless control unit 1. Wireless data transmission unit 203 and wireless data reception unit 204. In addition, a modulation unit 205 that converts data received from the wireless control unit 1 into wireless data and a demodulation unit 206 that converts data received from the wireless terminal PS into wired data are provided.

  The radio control unit 1 includes a control data transmission unit 301 and a control data reception unit 302 for transmitting / receiving control data to / from the radio unit 2, and a user data transmission unit 303 and user data for transmitting / receiving user data. A receiving unit 304. In addition, the radio control unit 1 includes a radio identifier generation unit 305 that generates a real radio identifier and a virtual radio identifier used as the radio identifier, and a radio resource allocation unit 306 that determines a radio resource distribution method. Details of the real radio identifier and the virtual radio identifier and details of operations of the radio identifier generation unit 305 and the radio resource allocation unit 306 will be described later.

  Next, the real radio identifier and the virtual radio identifier used in the radio base station apparatus S will be described in detail with reference to FIGS. 3 and 4.

  The actual wireless identifier is an identifier (ID) that is uniquely set in the system for each wireless unit 2, and the same value is not set for a plurality of wireless units 2 in normal operation. The radio terminal PS individually recognizes the radio unit 2 by detecting the actual radio identifier from the broadcast channel. FIG. 3 is a diagram illustrating an operation in which the wireless terminal PS individually detects the wireless unit 2 using the actual wireless identifier. When the wireless terminal PS1 is within the range of the wireless units 21 and 22, the wireless terminal PS1 recognizes the wireless units 21 and 22 to which the wireless terminal PS1 can connect by receiving the broadcast channel from the wireless units 21 and 22. The broadcast channel includes an actual radio identifier corresponding to each radio unit 2, and the radio terminal PS1 can distinguish that these broadcast channels are transmitted from different radio units 21 and 22. .

  On the other hand, the virtual wireless identifier is an identifier (ID) that can be used in common by the plurality of wireless units 2, unlike the actual wireless identifier. However, there is no difference between the virtual radio identifier and the real radio identifier from the radio terminal PS, and both are handled as radio identifiers. Therefore, data transmitted from two radio units 2 is actually transmitted from one radio unit 2. Can appear to be. FIG. 4 is a diagram illustrating an operation in which the wireless terminal PS detects the wireless unit 2 using the virtual wireless identifier. Since the radio units 21 and 22 use the same virtual radio identifier, the radio terminal PS1 recognizes that one radio cell is detected without distinguishing the radio units 21 and 22.

  5 and 6 show the difference in recognition of the wireless unit 2 by the wireless terminal PS when the real wireless identifier and the virtual wireless identifier are used.

  FIG. 5 shows a case where different real radio identifiers are transmitted from the two radio units 21 and 22. In FIG. 5, when communication is continued when the wireless terminal PS <b> 1 moves in the direction of the arrow and goes out of the range of the wireless unit 21, the wireless unit 22 needs to be handed over. If the wireless terminal PS1 is moving at high speed, the handover process may not be in time and communication may be disconnected.

  FIG. 6 shows a case where the same virtual wireless identifier is transmitted from the two wireless units 21 and 22. As a result, the wireless terminal PS1 can recognize that it is communicating with one wireless unit 2. In FIG. 6, even when communication is continued when the wireless terminal PS1 moves in the direction of the arrow and reaches the outside of the range of the wireless unit 21, there is no need for handover, and data received from the wireless unit 22 may be used. This is because both the radio units 21 and 22 communicate with the radio terminal PS1 using the same radio resource area, and is therefore a very useful technique for a terminal moving at high speed. However, since the same radio resource area is used by the two radio units 21 and 22, there is a problem that radio resources cannot be effectively used.

  Here, the operation of the radio base station apparatus S of the present embodiment will be described. FIG. 7 is a sequence diagram illustrating an example of the operation of the radio base station apparatus according to the present embodiment.

[Step S1: Generation of Wireless Identifier]
In step S1, the wireless identifier generation unit 305 of the wireless control unit 1 generates a real wireless identifier and a virtual wireless identifier. With reference to FIG. 8, the specific example of the real radio | wireless identifier and virtual radio | wireless identifier which are used with this radio base station apparatus S is demonstrated according to each Example.

Example 1
FIG. 8A shows a case where a real radio identifier and a virtual radio identifier are separated as handling of a radio identifier in the entire radio base station apparatus. In the first embodiment, if the leading wireless identifier is a number, it indicates a real wireless identifier, and if it is an alphabet, it indicates a virtual wireless identifier. In this example, the determination is based on the information of the first character, but the information to be distinguished can be set at an arbitrary position, and the determination may be made not only by one character but also by two or more characters. These can be negotiated by the system.

(Example 2)
FIG. 8B shows a case where the control data in the entire radio base station apparatus includes information on whether it is a real radio identifier or a virtual radio identifier. In the case of the second embodiment, as in the first embodiment, the wireless identifier itself does not include information for identifying whether it is a real wireless identifier or a virtual wireless identifier. The radio terminal PS may identify whether it is a real radio identifier or a virtual radio identifier from specific data in the received control data. In the example of FIG. 8B, when the virtual flag is ON, a virtual wireless identifier is indicated, and when it is OFF, an actual wireless identifier is indicated. There is no limit to the amount of information that distinguishes between a real wireless identifier and a virtual wireless identifier.

(Example 3)
FIG. 8 (c) shows a case of identifying whether it is a real radio identifier or a virtual radio identifier at the timing of transmitting control data in the entire radio base station apparatus. In the case of the third embodiment, it is assumed that 12 control data can be included in one cycle, and the first half 6 data is used as a real wireless identifier and the second half 6 data is used as a virtual wireless identifier. . Note that the periodicity of data can be determined from the sequence of types of control data to be set.

  In step S 1, the first embodiment is adopted, and the wireless identifier generation unit 305 generates an actual wireless identifier “012” for the wireless unit 21 and an actual wireless identifier “789” for the wireless unit 22. It is assumed that a virtual radio identifier “A12” common to the units 21 and 22 is generated.

[Step S2: Radio Resource Allocation]
In step S2, the radio resource assignment unit 306 of the radio equipment controller S assigns radio resources to the real radio identifier and the virtual radio identifier generated by the radio identifier generation unit 305. FIG. 9 shows a method of assigning radio resource areas used by real radio identifiers and virtual radio identifiers.

  In FIG. 9, an area for control data communication is allocated to the lowest frequency area in the radio resource area, and the other areas are allocated to user data communication areas. Further, in the time domain, the previous period is the real radio identifier use area, The period is divided into virtual wireless identifier usage areas. As described above, by dividing the resource area to be used, the real wireless identifier and the virtual wireless identifier can be mixed.

  Note that these resource allocations do not always have to be halved. The radio control unit 1 may expand the area of the virtual radio identifier when there are a large number of radio terminals PS having a high moving speed in the cover area. Further, when the number of connected wireless terminals PS increases, the area of the actual wireless identifier can be expanded. The area of the resource area used by each of the real wireless identifier and the virtual wireless identifier can be arbitrarily and dynamically set by the system.

[Step S3: Transmission of Radio Identifier]
In step S <b> 3, the control data transmission unit 301 of the wireless control unit 1 transmits the real wireless identifier and virtual wireless identifier generated by the wireless identifier generation unit 305 to the wireless terminal PS via the wireless units 21 and 22. The control data transmission unit 301 transmits the real radio identifier “012” and the virtual radio identifier “A12” to the radio terminal PS via the radio unit 21, and the real radio identifier “789” and the virtual radio identifier via the radio unit 22. “A12” is transmitted to the wireless terminal PS.

[Step S4: Reception of Radio Identifier]
In step S4, the control data receiving unit 102 of the radio terminal PS receives the real radio identifier “012” and the virtual radio identifier “A12” via the radio unit 21, and receives the real radio identifier “789” via the radio unit 22. And the virtual wireless identifier “A12” is received.

  FIG. 10 shows a state when the wireless terminal PS detects a wireless identifier.

  In FIG. 10A, the radio unit 21 transmits the broadcast channel (control data) of the real radio identifier 012 and the broadcast channel (control data) of the virtual radio identifier A12, and the radio unit 22 transmits the broadcast channel (control data) of the real radio identifier 789. Control data) and the broadcast channel (control data) of the virtual radio identifier A12 are transmitted. FIG. 10B shows the state of the broadcast channel in this case. When the real radio identifier is used in the radio unit 21 and the radio unit 22, the radio radio identifier must be transmitted at different timings. When using, transmission is performed at the same timing.

  In FIG. 10A, the wireless terminal PS can detect three wireless identifiers from the received data. Here, when Example 1 of FIG. 8A is applied, it can be recognized that A12 whose leading information is alphabet is a virtual wireless identifier and an identifier covering a wide area. The radio terminal PS can arbitrarily select a radio identifier to be used (real radio identifier / virtual radio identifier), that is, a radio cell, according to the situation in which the radio terminal PS is placed.

[Steps S5 to S7: Selection of Radio Identifier]
In steps S <b> 5 to S <b> 7, the radio identifier selection unit 105 of the radio terminal PS selects one of the real radio identifier and the virtual radio identifier received by the control data receiving unit 102. For example, the moving speed of the wireless terminal PS is compared with a predetermined threshold (step S5), and if the moving speed exceeds the threshold, a virtual wireless identifier is selected (step S7). A radio identifier is selected (step S6).

  Here, FIG. 11 shows a state when the wireless terminal PS selects an actual wireless identifier in step S6. FIG. 12 shows how the wireless terminal PS selects a virtual wireless identifier in step S7. The selection of the radio identifier is performed, for example, at the time of handover or the start of communication. The environment in FIGS. 11 and 12 is the same as that in FIG.

  In FIG. 11, it is assumed that the wireless terminal PS1 is moving at a low speed in the direction of the arrow in FIG. In this case, communication is not interrupted even if a handover is performed when the wireless unit 21 reaches an out-of-service area. Therefore, when the wireless terminal PS1 is moving at a low speed, communication is performed using the actual wireless identifier “012” in the communication area of the wireless unit 21 (step S6-1), and the communication area of the wireless unit 22 is reached. The actual wireless identifier “789” is switched to perform communication via the wireless unit 22 (step S6-2).

  Next, in FIG. 12, it is assumed that the wireless terminal PS1 is moving at high speed in the direction of the arrow in FIG. In this case, there is a high possibility that communication will be interrupted if a handover is performed when the wireless unit 21 reaches an out-of-service area. Therefore, when the wireless terminal PS1 is moving at high speed, communication is performed using the virtual wireless identifier “A12” (step S7-1). For example, the moving speed of the radio terminal PS1 can be estimated from the time interval at which the terminal itself performs handover. In FIG. 7, the wireless terminal PS1 can cope with the case where the speed changes during communication by repeatedly performing steps S4 to S7 during communication.

  In the examples of FIG. 10, FIG. 11, and FIG. 12, there is a method of selecting a radio identifier to be used from the viewpoint of the moving speed of the terminal. From the viewpoint of radio resources, the number of resources that can be used when using virtual radio identifiers Has a problem of decreasing due to interference of radio waves transmitted by the wireless units 21 and 22. Therefore, the radio identifier to be used is selected according to the time zone so that the real radio identifier is used as much as possible in the time zone with a large number of communication, and the virtual identifier is used in the time zone with a small number of communication such as midnight. It is also possible.

  In the above embodiment, the wireless identifier generation unit 305 generates both the real wireless identifier and the virtual wireless identifier. However, the moving speed is within the cover area formed by the wireless unit 2 belonging to the wireless control unit 1. When there is no fast wireless terminal PS, it is not necessary to generate a virtual wireless identifier. The radio control unit 1 can generate a virtual radio identifier as necessary based on the situation such as the number of radio terminals PS in the cover area and the moving speed.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 200 ... Gateway apparatus, S ... Wireless base station apparatus, 1 ... Wireless control part, 300 ... IP network, 400 ... PSTN network, PS1-PSm ... Wireless terminal, 21-2n ... Wireless part, 101 ... Control data transmission part, 102 ... Control data receiving unit 103 ... User data transmitting unit 104 ... User data receiving unit 105 ... Wire identifier selection unit 201 ... Wired data transmitting unit 202 ... Wired data receiving unit 203 ... Wireless data transmitting unit 204 ... Wireless data reception unit, 205 ... modulation unit, 206 ... demodulation unit, 301 ... control data transmission unit, 302 ... control data reception unit, 303 ... user data transmission unit, 304 ... user data reception unit, 305 ... radio identifier generation unit, 306: A radio resource allocation unit.

Claims (21)

A wireless communication system comprising a wireless terminal and a wireless base station device that performs wireless communication with the wireless terminal through a plurality of wireless units forming a wireless cell,
The wireless base station device
An identifier generating unit that generates a first identifier that is uniquely set for each wireless unit and a second identifier that is commonly set by the plurality of wireless units;
A radio resource allocating unit that allocates radio resources that can be used in radio communication by the first identifier to each radio unit, and that allocates radio resources that can be used in radio communication by the second identifier to the plurality of radio units;
A transmission unit for transmitting the control data including the first identifier and the second identifier to the wireless terminal;
Comprising
The wireless terminal is
A control data receiving unit for receiving the control data transmitted from the radio base station apparatus;
An identifier selection unit that selects an identifier to be used for the wireless communication from among the first identifier and the second identifier included in the control data according to a use situation of the terminal;
A wireless communication system comprising: The identifier selecting unit selects the first identifier when the moving speed of the terminal is equal to or less than a threshold value, and selects the second identifier when the moving speed exceeds the threshold value. The wireless communication system according to 1. The wireless communication system according to claim 1, wherein the identifier selecting unit selects the identifier to be used according to a time zone in which the terminal is used. The wireless communication system according to claim 1, wherein the second identifier is configured with an identifier system different from the first identifier. The second identifier is configured with the same identifier system as the first identifier, and the control data transmission unit transmits the second identifier together with information indicating that the second identifier is included in the control data. The wireless communication system according to claim 1. The wireless communication system according to claim 1, wherein the transmission unit transmits the first identifier and the second identifier to the wireless terminal via the wireless unit at different transmission timings. The radio resource allocation unit divides, in a time domain, a radio resource that can be used for radio communication by the first identifier and a radio resource that can be used for radio communication by the second identifier. The wireless communication system described. The radio resource allocation unit dynamically changes an area used by the second identifier and an area used by the first identifier according to a moving speed of a radio terminal in communication with the radio unit. The wireless communication system according to claim 1 . Before Ki識 Besshi generator, when the moving speed of the radio terminal exceeds the threshold value of the wireless terminal in communication with the wireless unit is not present, according to claim 1, characterized in that does not generate the second identifier The wireless communication system according to 1 . The radio resource allocation unit dynamically changes an area used by the second identifier and an area used by the first identifier according to the number of radio terminals in communication with the radio unit. The wireless communication system according to claim 1 . The continuously-ray base station apparatus for performing radio communication with the radio terminal via a plurality of radio units that form a non-linear cell,
A first identifier set uniquely for each front Symbol wireless unit, an identifier generation unit for generating a second identifier set in common by the plurality of radio units,
A radio resource allocating unit that allocates radio resources that can be used in radio communication by the first identifier to each radio unit, and that allocates radio resources that can be used in radio communication by the second identifier to the plurality of radio units ;
Depending on the usage of the wireless terminal, in order to select the identifier used for the wireless communication of the first identifier and the second identifier, said control data including said first identifier and said second identifier the radio base station apparatus, characterized by a transmission unit that transmits before Symbol wireless terminal. The radio base station apparatus according to claim 11 , wherein the second identifier is configured with an identifier system different from the first identifier. The second identifier is configured with the same identifier system as the first identifier, and the control data transmission unit transmits the second identifier together with information indicating that the second identifier is included in the control data. The radio base station apparatus according to claim 11 . And the transmission unit, the radio base station apparatus according to claim 11, characterized that you send to the wireless terminal and said second identifier and said first identifier via the radio unit at different transmission timings. The radio resource allocating unit divides, in a time domain, a radio resource that can be used for radio communication by the first identifier and a radio resource that can be used for radio communication by the second identifier. The radio base station apparatus described. The radio resource allocation unit dynamically changes an area used by the second identifier and an area used by the first identifier according to a moving speed of a radio terminal in communication with the radio unit. The radio base station apparatus according to claim 11 . Before Ki識 Besshi generator, when the moving speed of the radio terminal exceeds the threshold value of the wireless terminal in communication with the wireless unit is not present, according to claim characterized in that it does not generate the second identifier 11 The radio base station apparatus described in 1. The radio resource allocation unit dynamically changes an area used by the second identifier and an area used by the first identifier according to the number of radio terminals in communication with the radio unit. The radio base station apparatus according to claim 11 . A plurality of radio units that form the radio cells to generate a second identifier set the first identifier set uniquely in common by the plurality of radio units for each of the radio unit, the second 1 identifier assigning radio resources available in the radio communication for each of the wireless unit by radio communication with the radio base station apparatus for allocating radio resources available in the radio communication to the plurality of radio units by the second identifier A wireless terminal that performs
A control data receiving unit for receiving control data including said second identifier before Symbol first identifier transmitted from the radio base station apparatus,
A wireless terminal comprising: an identifier selection unit that selects an identifier to be used for the wireless communication from among the first identifier and the second identifier included in the control data according to a use situation of the terminal. . The said identifier selection part selects the said 1st identifier when a moving speed is below a threshold value, and selects the said 2nd identifier when the said moving speed exceeds a threshold value, The Claim 19 characterized by the above-mentioned. Wireless terminal. The wireless terminal according to claim 19 , wherein the identifier selection unit selects the identifier to be used according to a time zone.

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