WO2013140528A1

WO2013140528A1 - Base station device, mobile station device, communication system, and communication method

Info

Publication number: WO2013140528A1
Application number: PCT/JP2012/057076
Authority: WO
Inventors: 裕磯沼
Original assignee: 富士通株式会社
Priority date: 2012-03-19
Filing date: 2012-03-19
Publication date: 2013-09-26

Abstract

The base station device (2) is provided with: a scheduler (42) for assigning a wireless resource for a wireless signal transmitted by a first cell (5), for transmission of a control signal to or from a mobile station device (3), and for assigning a wireless resource for a wireless signal transmitted by a second cell (6) different from the first cell (5), for transmission of user traffic to or from the mobile station device (3); and a signal transmitter/receiver (43) for transmitting and receiving control signals and user traffic to and from the mobile station device (3), in accordance with the wireless resource assignments made by the scheduler (42).

Description

Base station apparatus, mobile station apparatus, communication system, and communication method

The embodiments discussed herein relate to the formation of cells used for mobile communications.

A first base station that forms a first cell and can communicate with a mobile station, and a second base station that forms a second cell and can communicate with the mobile station Mobile communication systems have been proposed. The first base station can transmit the first radio signal including the same cell information regarding the first cell a plurality of times. The second base station receives the first radio signal including the same cell information at least once, and the cell information included in the received first radio signal is valid until a predetermined time has elapsed or until a predetermined time. To do. The second base station adjusts radio parameters related to the second cell based on the cell information.

JP2011-97142A

In cellular mobile communication, when user traffic increases, the capacity of traffic per cell may be insufficient. In this case, the amount of user traffic accommodated per cell can be reduced by reducing the coverage range of each cell and increasing the cell arrangement density to reduce the number of mobile station apparatuses accommodated per cell.

On the other hand, when the mobile station apparatus moves between cells, a handover process is performed to maintain a connection between the mobile station apparatus and the base station apparatus of the movement destination. In the following description, handover may be referred to as “HO”. Since HO processing involves transmission and reception of control messages, radio resources are consumed. As the coverage area of one cell becomes smaller, HO processing increases. For this reason, an increase in radio resources used for the HO processing may reduce the amount of radio resources that can be used for user traffic, and may reduce the utilization efficiency of radio resources.

The disclosed apparatus, system, and method alleviate an increase in HO processing due to a reduction in the coverage range of a cell that accommodates user traffic.

According to one aspect of the device, a base station device is provided. The base station apparatus allocates radio resources of radio signals transmitted in the first cell to control signal transmission with the mobile station apparatus, and allocates radio resources of radio signals transmitted in a second cell different from the first cell. And a scheduler assigned to transmission of user traffic to and from the mobile station apparatus. The base station apparatus includes a signal transmission / reception unit that transmits and receives control signals and user traffic to and from the mobile station apparatus in accordance with radio resource allocation by the scheduler.

According to another aspect of the device, a mobile station device is provided. The mobile station apparatus includes a scheduling information detection unit that detects scheduling information. The scheduling information designates a second cell different from the first cell, which is used for transmission of user traffic with the base station apparatus, from a radio signal transmitted in the first cell. The scheduling information specifies a radio resource of a radio signal transmitted in the second cell allocated for transmission of user traffic. The mobile station apparatus includes a user traffic transmission / reception unit that transmits / receives user traffic using radio resources of radio signals transmitted in the second cell, which are designated by the scheduling information.

According to another aspect of the apparatus, a communication system is provided. The communication system includes a base station device and a mobile station device. The base station apparatus allocates radio resources of radio signals transmitted in the first cell to control signal transmission with the mobile station apparatus, and allocates radio resources of radio signals transmitted in a second cell different from the first cell. A scheduler assigned to transmission of user traffic to and from the mobile station apparatus is provided. The base station apparatus includes a control signal transmission unit that transmits scheduling information in the first cell. The scheduling information specifies a radio resource allocated by the scheduler for transmission of user traffic and a second cell used for transmission of user traffic. The base station apparatus includes a control signal transmission unit that transmits in the first cell and a user traffic transmission / reception unit that transmits and receives user traffic to and from the mobile station apparatus according to radio resource allocation by the scheduler. The mobile station apparatus includes a scheduling information detection unit that detects scheduling information from a radio signal transmitted in the first cell. The mobile station apparatus includes a user traffic transmission / reception unit that transmits / receives user traffic using radio resources of radio signals transmitted in the second cell, which are designated by the scheduling information.

According to one aspect of the method, a communication method is given. In the communication method, radio resources of radio signals transmitted in the first cell are allocated to control signal transmission between the base station apparatus and the mobile station apparatus. In the communication method, radio resources of radio signals transmitted in a second cell different from the first cell are allocated to transmission of user traffic between the base station apparatus and the mobile station apparatus.

According to the disclosed apparatus, system, or method, an increase in HO processing is reduced even if the coverage range of a cell that accommodates user traffic is reduced.

The objects and advantages of the invention will be realized and attained by means of the elements and combinations shown in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.

It is a figure which shows the structural example of a communication system. It is explanatory drawing of an example of cell notification information. It is explanatory drawing of an example of cell quality information. It is explanatory drawing of an example of scheduling information. It is a figure which shows an example of the hardware constitutions of a mobile station apparatus. It is an example of the functional block diagram of a mobile station apparatus. It is a figure which shows an example of the hardware constitutions of a base station apparatus. It is an example of the functional block diagram of a base station apparatus. It is explanatory drawing of the operation | movement at the time of call origination. It is explanatory drawing of the movement between U plane cells. It is explanatory drawing of the operation | movement at the time of a hand-over.

<1. System configuration>
Hereinafter, preferred embodiments will be described with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a configuration example of a communication system. The communication system 1 includes

base station devices

2 a and 2 b and a mobile station 3. In the following description, a base station device and a mobile station device may be referred to as a base station and a mobile station, respectively. Further, the

base stations

2a and 2b may be collectively referred to as the base station 2.

The base station 2 is a radio station device that relays between a mobile station 3 of a user who receives a mobile communication service and a fixed communication network in accordance with a predetermined radio communication standard. The wireless communication standard of the base station 2 may be, for example, a W-CDMA (Wideband Code Division Multiple Access) system or an LTE (Long Term Evolution) system. The mobile station 3 is a terminal device used for communication via the Internet such as the Web or communication such as voice via a public line / other mobile communication network.

The base station 2a includes a first cell 5a for transmitting a control signal to and from the mobile station 3, and

second cells

6a and 6b for transmitting user traffic to and from the mobile station 3. Form separately. The base station 2b separately forms a first cell 5b for transmitting control signals to and from the mobile station 3 and a second cell 6c for transmitting user traffic to and from the mobile station 3. .

In the following description, the

first cells

5a and 5b may be referred to as C-

plane cells

5a and 5b. The second cells 6a to 6c may be referred to as U-plane cells 6a to 6c. Further, the

C plane cells

5a and 5b may be collectively referred to as the C plane cell 5. The U plane cells 6a to 6c may be collectively referred to as a U plane cell 6.

The base station 2a of this embodiment includes radio devices (RE: “Radio” Equipment) 4a and 4b. Similarly, the base station 2b includes a wireless device 4c. The radio apparatuses 4a to 4c include a communication interface with the base station 2, a digital-analog converter, a digital-analog converter, a frequency converter, a transmission amplifier, a transmission amplifier, and a reception amplifier. The wireless communication with the mobile station 3 is relayed. An example of the wireless devices 4a to 4c is, for example, a remote radio head (RRH: “Remote Radio Radio Head”).

The base station 2a forms coverage by the relay of the

wireless devices

4a and 4b as

U cells

6a and 6b, and the base station 2b forms coverage by the relay of the wireless device 4c as the U cell 6c. In the following description, the wireless devices 4a to 4c may be collectively referred to as the wireless device 4. In another embodiment, the base station 2 may form the C cell 5 by coverage by relay of the wireless device 4. Further, the base station 2 may form the U cell 6 with the coverage of the base station 2 itself.

In one embodiment, the coverage range of one U plane cell 6 is smaller than the coverage range of one C plane cell 5. By reducing the number of U-plane cells 6 that transmit user traffic, the number of mobile stations 3 accommodated per U-plane cell 6 is reduced, and the radio resources that can be used by one mobile station 3 to transmit user traffic increase. To do.

On the other hand, a control signal used for connection connection between the mobile station 3 and the base station 2 is transmitted and received in the C plane cell 5. For this reason, the HO process for maintaining the connection between the mobile station 3 and the base station 2 is performed when the mobile station 3 moves between the C plane cells 5. Therefore, by making the C plane cell 5 larger than the U plane cell 6, even if the U plane cell 6 is downsized, radio resource consumption due to an increase in HO processing is reduced.

Also, the recent increase in the traffic volume of the entire network is due to the increase in user traffic, and the increase in control signals is small compared to the increase in user traffic. Therefore, if the cell that transmits the control signal is reduced in accordance with the reduction of the cell that transmits the user traffic, the control signal processing capability in the base station 2 is left. By making the C plane cell 5 larger than the U plane cell 6, even if the U plane cell 6 is reduced, the reduction in the number of mobile stations 3 per base station 2 is reduced, and the control signal processing in the base station 2 is reduced. It is possible to prevent excess capacity.

The control signal processing in the C plane cell 5a and the user traffic processing in the U plane cells 6a and 6c included in the coverage of the C plane cell 5a are performed by the same base station 2a. That is, the U plane cells 6a and 6c in which user traffic is processed by a certain base station 2a are included in the coverage of the C plane cell 5a in which control signals are processed by the same base station 2a.

Similarly, control signal processing in the C plane cell 5b and user traffic processing in the U plane cell 6c included in the coverage of the C plane cell 5b are performed by the same base station 2a. Note that the coverage of the

U plane cell

6a or 6b included in a certain C plane cell 5a does not necessarily have to be included in the C plane cell 5a. The partial range of the

U plane cell

6a or 6b may be outside the C plane cell 5a, and the connection with a certain base station 2a may not be maintained.

In one embodiment, the C-

plane cells

5a and 5b use the carrier frequency f1, and the U-plane cells 6a to 6c use a carrier frequency f2 different from f1. In some embodiments, if the interference between the transmission signal in the C plane cell 5 and the transmission signal in the U plane cell 6 can be avoided by some means, the same carrier frequency is used in the C plane cell 5 and the U plane cell 6. May be. For example, CDMA (Code Division Multiple Access) may be used to avoid interference.

<2. Overview of user traffic transmission operations>
Next, an outline of a user traffic transmission operation in the communication system 1 will be described. In the following description, an example of a communication system according to the LTE scheme is used. However, this illustration is not intended to apply the communication system described herein to the LTE system. The communication system described in this specification can be widely applied to mobile communication systems that adopt a cellular system.

In the case of the LTE system, control signals passing through the following channels are transmitted / received in the C plane cell 5.
(1) PRACH (Physical Random Access Channel)
(2) PUCCH (Physical Uplink Control Channel)
(3) PDCCH (Physical Downlink Control Channel)
(4) CCCH (Common Control Channel) and DCCH (Dedicated Control Channel) mapped to PUSCH (Physical Uplink Shared Channel)
(5) PCCH (Paging Control Channel), BCCH (Broadcast Control Channel), CCCH, and DCCH mapped to PDSCH (Physical Uplink Shared Channel)

Also, in the U plane cell 6, user traffic on DTCH (Dedicated Traffic) mapped to PUSCH and PDSCH is transmitted.

<2.1. Obtaining cell notification information>
The base station 2 transmits cell notification information as broadcast information via the BCCH. The cell notification information is information for notifying the U plane cell 6 formed by the base station 2. FIG. 2 shows an example of cell notification information. The cell notification information of an embodiment may include information elements “cell identifier” and “frequency”.

The information element “cell identifier” is an identifier of the U-plane cell 6 formed by the base station 2. The information element “frequency” indicates the carrier frequency in each U-plane cell 6. The cell notification information may be transmitted as one of SIB (System Information Block), for example. The base station 2 transmits cell notification information of all U plane cells 6 formed by the base station 2. The mobile station 3 acquires cell notification information from the received broadcast information.

<2.2. Acquisition of reference signal and synchronization signal in U-plane cell 6>
The base station 2 inserts a reference signal and a synchronization signal including a pattern unique to each U plane cell 6 into a radio signal transmitted to the U plane cell 6. The reference signal includes a pattern specific to each U-plane cell 6, and the mobile station 3 can identify the U-plane cell 6 based on the reference signal. The synchronization signal is a signal whose position is determined in the time domain, and the mobile station 3 can perform symbol synchronization based on the synchronization signal.

<2.3. Calling action>
When starting communication, the mobile station 3 connects to the base station 2 by transmitting and receiving control signals in the C plane cell 5. The mobile station 3 detects the U plane cell 6 to which the received reference signal is transmitted based on the reception result of the reference signal transmitted from the U plane cell 6. The mobile station 3 measures the reception strength of the reference signal for each U plane cell 6. The mobile station 3 selects the upper predetermined number of U-plane cells 6 having higher reception strength.

The mobile station 3 transmits cell quality information including the identifier and reception strength of the selected U-plane cell 6 to the base station 2 as an RRC (Radio Resource Control) protocol message via the DCCH. FIG. 3 shows an example of cell quality information. The cell quality information includes information elements “message type”, “number of cells”, and “cell information”. The information element “message type” is an identifier indicating that this message is cell quality information. The information element “number of cells” indicates how many cells the cell quality information includes.

Each of the information elements “cell information” further includes an information element “identifier” and “reception strength”. The cell quality information includes an information element “cell information” corresponding to the number of values of the information element “number of cells”. The information elements “identifier” and “reception strength” indicate the identifier and reception strength of the U-plane cell 6 selected by the mobile station.

<2.4. Send user traffic>
The base station 2 selects the U plane cell 6 used for communication with the mobile station 3 from the U plane cells 6 specified by the cell quality information. In the following description, it is assumed that

U-plane cells

6a and 6b are available. The base station 2 determines radio resources to be allocated for communication with the mobile station 3 from the available radio resources in both the

U plane cells

6a and 6b.

The base station 2 transmits resource information specifying the assigned radio resource in the C plane cell 5 using PDCCH. The schedule information may include a cell identifier of the U plane cell 6 used for transmission of user traffic between the base station 2 and the mobile station 3, and an identifier of a radio resource. The radio resource identifier may include, for example, a channel number and a slot number used for transmission.

FIG. 4 is an explanatory diagram of an example of scheduling information. In FIG. 4, scheduling information for downlink to the mobile station 3 is transmitted in the third slot on the PDCCH which is a control signal channel. In the

U-plane cells

6a and 6b, n channels for user traffic transmission are prepared in the PDSCH, and each channel has 15 slots. The scheduling information shown in the figure indicates that downlink user traffic to the mobile station 3 is transmitted in the twelfth slot of the first channel of the U plane cell 6b.

The mobile station 3 acquires scheduling information assigned to the mobile station 3 from the PDCCH. The mobile station 3 acquires user traffic by descrambling a signal transmitted using the radio resource specified by the scheduling information using a scrambling code unique to the U-plane cell 6b. Also, the mobile station 3 scrambles the encoded uplink user traffic using a scramble code unique to the U-plane cell 6b, and transmits the scrambled code using radio resources specified by the scheduling information. By scrambling user traffic with a scramble code unique to the U-plane cell 6b, interference between the U-plane cells 6 can be removed, and signals transmitted in the U-plane cells 6 can be distinguished.

<3. Mobile station device>
<3.1. Hardware configuration>
Next, each component of the communication system 1 will be described. FIG. 5 is a diagram illustrating an example of a hardware configuration of the mobile station 3. The hardware configuration illustrated in FIG. 5 is one example of a hardware configuration that implements the mobile station 3. Any other hardware configuration may be adopted as long as it performs the operations described below. The mobile station 3 includes a processor 10, a memory 11, an LSI (Large Scale Integration) 12, a wireless communication circuit 13, an interface circuit 14, an input device 15, and an output device 16. In the accompanying drawings, the interface circuit is denoted as “I / F”.

The processor 10 executes information processing of application software used by the user of the mobile station 3 and communication protocol processing for wireless communication with the base station 2 by executing a computer program stored in the memory 11. To do. The memory 11 stores a computer program executed by the processor 10 and data used for the execution. The memory 11 may include a non-volatile storage device for storing programs and data, and a random access memory (RAM: “Random Access” Memory) for storing temporary data.

The LSI 12 executes baseband signal processing of radio signals with the base station 2 transmitted and received by the radio communication circuit 13. The LSI 12 may be, for example, an FPGA (Field-Programming Gate Array), an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), or the like. The radio communication circuit 13 transmits and receives radio signals between the mobile station 3 and the base station 2.

The interface circuit 14 is an interface circuit between the processor 10 and the following input device 15 and output device 16. The input device 15 is an input device that accepts an input operation by a user. The input device 15 may be, for example, a keypad, a keyboard, a pointing device, a touch panel, or the like. The output device 16 is an output device that outputs a signal processed by the mobile station apparatus 3. For example, the output device 16 may be a display device that visually displays information processed by the mobile station device 3 to the user. This display device may be, for example, a liquid crystal display or an organic electroluminescence display. Alternatively, the output device 16 may be a speaker that outputs an audio signal or a drive circuit thereof.

<3.2. Functional configuration>
Next, functions of each unit of the mobile station 3 will be described. FIG. 6 is an example of a functional block diagram of the mobile station 3. FIG. 6 mainly shows functions related to the following description. The mobile station 3 may include other components than the illustrated components. The mobile station 3 includes a C plane signal processing unit 20, a U plane signal processing unit 21, a communication control unit 22, a communication processing unit 23, and an application processing unit 24. A solid line indicates the flow of user traffic and control signals transmitted to and received from the base station 2, and a broken line indicates the flow of control signals used in the mobile station 3.

The following operations of the communication control unit 22, the communication processing unit 23, and the application processing unit 24 are executed by the processor 10 shown in FIG. The operations of the C plane signal processing unit 20 and the U plane signal processing unit 21 are executed by the cooperation of the LSI 12 and the wireless communication circuit 13.

The C-plane signal processing unit 20 performs radio signal transmission / reception processing, encoding processing, decoding processing, modulation processing, and demodulation processing of control signals transmitted and received in the C-plane cell 5. The U plane signal processing unit 21 performs transmission / reception processing, encoding processing, decoding processing, modulation processing, and demodulation processing of radio signals of user traffic transmitted and received in the U plane cell 6.

In addition, the U plane signal processing unit 21 identifies the U plane cell 6 that can be used by the mobile station 3 based on the reference signal and the synchronization signal transmitted for each U plane cell 6, symbol synchronization, and the U plane cell. The reception strength measurement at 6 is performed. The U plane signal processing unit 21 outputs the detected identifier of the U plane cell 6 and the reception strength measurement result to the application processing unit 24.

The U plane signal processing unit 21 receives from the application processing unit 24 a scramble code used in the U plane cell 6 through which user traffic is transmitted and received. The U-plane signal processing unit 21 performs a scramble process and a descrambling process with the scramble code specified by the application processing unit 24 in the encoding process and decoding process of user traffic.

The communication control unit 22 performs termination processing of PUCCH, PRACH, and PDCCH, and transmission control and reception control of signals transmitted and received by the communication processing unit 23. In downlink communication, the communication control unit 22 acquires schedule information indicating radio resources allocated on the PDSCH for downlink communication from the PDCCH. The communication control unit 22 outputs the schedule information to the communication processing unit 23, the C plane signal processing unit 20, and the U plane signal processing unit 21.

In uplink communication, upon receiving a signal transmission request from the communication processing unit 23, the communication control unit 22 sends an uplink radio resource allocation request used for signal transmission to the base via the C plane signal processing unit 20. Transmit to station 2. The radio resource allocation request is transmitted via the PUCCH. The communication control unit 22 acquires schedule information indicating radio resources allocated on the PUSCH for uplink communication from the PDCCH. The communication control unit 22 outputs the schedule information to the communication processing unit 23, the C plane signal processing unit 20, and the U plane signal processing unit 21.

The communication processing unit 23 transmits / receives control signals and user traffic to / from the application processing unit 24 and PUSCH and PDSCH termination processing. In the downlink, the communication processing unit 23 receives the PDSCH from the C plane signal processing unit 20 and / or the U plane signal processing unit 21 according to the schedule information output from the communication control unit 22. Further, the communication processing unit 23 outputs a control signal and user traffic transmitted on the PDSCH to the application processing unit 24.

When receiving a control signal and / or user traffic from the application processing unit 24 in the uplink, the communication processing unit 23 outputs a signal transmission request to the communication control unit 22. When a transmission instruction from the communication control unit 22 is received, a PUSCH signal containing a control signal and / or user traffic is output to the C plane signal processing unit 20 and / or the U plane signal processing unit 21. The C plane signal processing unit 20 and the U plane signal processing unit 21 transmit a PUSCH signal using radio resources specified by the schedule information in accordance with the schedule information output from the communication control unit 22.

Further, the communication processing unit 23 detects cell notification information transmitted from the base station 2 as broadcast information via BCCH. The communication processing unit 23 transmits cell notification information to the application processing unit 24.

The application processing unit 24 executes information processing of application software used by the user of the mobile station 3, transmission / reception of user traffic on the logical channel, and communication protocol processing for wireless communication with the base station 2.

When receiving the cell notification information from the communication processing unit 23, the application processing unit 24 outputs the identifiers and carrier frequency information of all the U plane cells 6 formed by the base station 2 to the U plane signal processing unit 21. The U plane signal processing unit 21 performs identification of the U plane cell 6, symbol synchronization, and reception intensity measurement in the U plane cell 6 based on the identifier of the U plane cell 6 and information on the carrier frequency.

The application processing unit 24 selects the upper predetermined number of U plane cells 6 having higher reception strength based on the measurement result of the reception strength by the U plane signal processing unit 21. The application processing unit 24 generates cell quality information including the identifier and reception strength of the selected U plane cell 6. The application processing unit 24 transmits an RRC protocol message notifying cell quality information to the base station 2 via the communication processing unit 23 and the C plane signal processing unit 20.

Also, the application processing unit 24 selects a scramble code to be used for scrambling user traffic from known scramble codes designated in advance for each U-plane cell 6. The application processing unit 24 outputs the selected scramble code to the U plane signal processing unit 21.

<4. Base station equipment>
<4.1. Hardware configuration>
Next, the base station 2 will be described. FIG. 7 is a diagram illustrating an example of a hardware configuration of the base station 2. The hardware configuration illustrated in FIG. 7 is an example of a hardware configuration that implements the base station 2. Any other hardware configuration may be adopted as long as it performs the operations described below. The base station 2 includes a processor 30, an auxiliary storage device 31, a memory 32, an LSI 33, a wireless communication circuit 34, and a network interface circuit 35. In the accompanying drawings, the network interface circuit is referred to as “NIF circuit”.

The processor 30 executes a computer program stored in the auxiliary storage device 31 to execute control of the base station 2 and communication protocol processing for wireless communication with the mobile station 3. The auxiliary storage device 31 stores a computer program executed by the processor 30 and data used for the execution. The auxiliary storage device 31 may include a nonvolatile memory, a read-only memory (ROM: “Read” Only ”Memory), a hard disk, and the like as storage elements.

The memory 32 stores a program currently being executed by the processor 30 and data temporarily used when the program is executed. The memory 32 may include a random access memory. The LSI 33 performs baseband signal processing of radio signals with the mobile station 3 in the C plane cell 5 transmitted and received by the radio communication circuit 34 and radio signals with the mobile station 3 in the U plane cell 6 transmitted and received by the radio apparatus 4. Execute.

The radio communication circuit 34 transmits and receives radio signals between the mobile station 3 and the base station 2 in the C plane cell 5. The network interface circuit 35 is a communication interface circuit for communication with other base stations and higher-level node devices via a fixed communication network.

<4.2. Functional configuration>
Next, functions of each unit of the base station 2 will be described. FIG. 8 is an example of a functional block diagram of the base station 2. FIG. 8 mainly shows functions related to the following description. The base station 2 may include other components other than the illustrated components. The base station 2 includes a C plane signal processing unit 40, a U plane signal processing unit 41, a communication control unit 42, a communication processing unit 43, and an application processing unit 44. The solid line indicates the flow of user traffic and control signals transmitted to and received from the mobile station 3, and the broken line indicates the flow of control signals used in the base station 2.

The following operations of the communication control unit 42, the communication processing unit 43, and the application processing unit 44 are executed by the processor 30 shown in FIG. The operation of the C plane signal processing unit 40 is executed by the cooperation of the LSI 33 and the wireless communication circuit 34. The operation of the U plane signal processing unit 21 is executed by the cooperation of the LSI 33 and the wireless device 4.

The C plane signal processing unit 40 performs radio signal transmission / reception processing, encoding processing, decoding processing, modulation processing, and demodulation processing of control signals transmitted and received in the C plane cell 5. The U plane signal processing unit 41 performs transmission / reception processing, encoding processing, decoding processing, modulation processing, and demodulation processing of radio signals of user traffic transmitted / received in the U plane cell 6. The U plane signal processing unit 41 inserts a cell-specific reference signal and a synchronization signal into the radio signal transmitted by each U plane cell 6.

Also, the U plane signal processing unit 41 receives a scramble code used in the U plane cell 6 through which user traffic is transmitted and received from the application processing unit 44. The U-plane signal processing unit 41 performs scramble processing and descrambling processing with the scramble code specified by the application processing unit 44 in the encoding processing and decoding processing of user traffic.

The communication control unit 42 performs termination processing of PUCCH, PRACH, and PDCCH, and transmission control and reception control of signals transmitted and received by the communication processing unit 43. In downlink communication, when receiving a signal transmission request from the communication processing unit 43, the communication control unit 42 determines a cell and radio resource to be used for transmission, and generates schedule information. At this time, if the transmission signal is a control signal, the communication control unit 42 uses the C plane cell 5 for transmission. If the transmission signal is user traffic, the communication control unit 42 uses one of the U plane cells 6 specified in the cell quality information received from the mobile station 3 for transmission. When there are free radio resources in the plurality of U plane cells 6 specified in the cell quality information, the communication control unit 42 may preferentially use a cell with higher reception strength.

The communication control unit 42 transmits schedule information to the mobile station 3 via the C plane signal processing unit 40 using PDCCH. The communication control unit 42 notifies the communication processing unit 43 of schedule information. The communication control unit 42 notifies the C plane signal processing unit 40 of the schedule information if the transmission signal is a control signal, and notifies the U plane signal processing unit 41 of the schedule information if the transmission signal is user traffic. The C plane signal processing unit 40 transmits the control signal output from the communication control unit 42 according to the schedule information. The U plane signal processing unit 41 transmits user traffic output from the communication control unit 42 according to the schedule information.

In uplink communication, the communication control unit 42 detects an uplink radio resource allocation request by the mobile station 3 from the PUCCH. The communication control unit 42 determines a cell and a radio resource used for receiving an uplink signal from the mobile station 3, and generates schedule information. The communication control unit 42 uses the C plane cell 5 for reception if the received signal is a control signal. If the received signal is user traffic, the communication control unit 42 uses one of the U plane cells 6 specified in the cell quality information received from the mobile station 3 for reception. When there are free radio resources in the plurality of U plane cells 6 specified in the cell quality information, the communication control unit 42 may preferentially use a cell with higher reception strength.

The communication control unit 42 transmits schedule information to the mobile station 3 via the C plane signal processing unit 40 using PDCCH. The communication control unit 42 notifies the communication processing unit 43 of schedule information. The communication control unit 42 notifies the C plane signal processing unit 40 of the schedule information if the received signal is a control signal, and notifies the U plane signal processing unit 41 of the schedule information if the received signal is user traffic. The C plane signal processing unit 40 detects the control signal transmitted by the mobile station 3 from the radio resource indicated by the schedule information. The U plane signal processing unit 41 detects user traffic from the radio resource indicated by the schedule information.

Further, the communication control unit 42 transmits cell notification information via BCCH.

The communication processing unit 43 performs PUSCH and PDSCH termination processing, and transmission and reception of control signals and user traffic between the application processing unit 44. In the downlink, when receiving a control signal and / or user traffic from the application processing unit 44, the communication processing unit 43 outputs a signal transmission request to the communication control unit 42. When a transmission instruction from the communication control unit 42 is received, a PDSCH signal containing a control signal and / or user traffic is output to the C plane signal processing unit 40 and / or the U plane signal processing unit 41. The C plane signal processing unit 40 and the U plane signal processing unit 41 transmit the PDSCH signal using radio resources specified by the schedule information in accordance with the schedule information output from the communication control unit 42.

In the uplink, the communication processing unit 43 receives the PUSCH from the C plane signal processing unit 40 and / or the U plane signal processing unit 41 in accordance with the schedule information output from the communication control unit 42. The communication processing unit 43 outputs the control signal and user traffic transmitted by the PUSCH to the application processing unit 44.

The application processing unit 44 executes control of the base station 2, transmission / reception of user traffic on the logical channel, and communication protocol processing for wireless communication with the mobile station 3. Further, the application processing unit 44 receives an RRC protocol message for notifying cell quality information from the mobile station 3 via the C plane signal processing unit 40 and the communication processing unit 43. The application processing unit 44 notifies the communication control unit 42 of the received cell quality information.

Also, the application processing unit 44 selects a scramble code to be used for scrambling user traffic from known scramble codes specified in advance for each U-plane cell 6. The application processing unit 44 outputs the selected scramble code to the U plane signal processing unit 41.

<5. Operation when calling>
Next, the operation of the communication system 1 according to the present embodiment will be described. FIG. 9 is an explanatory diagram of the operation of the communication system 1 at the time of calling. The series of operations described with reference to FIG. 9 may be interpreted as a method including a plurality of procedures. In this case, “operation” may be read as “step”. The same applies to the operation described with reference to FIG.

In operation AA, the base station 2a transmits broadcast information via the BCCH. The broadcast information is transmitted in the C plane cell 5. At this time, the communication control unit 42 transmits cell notification information as broadcast information. The mobile station 3 receives cell notification information. In operation AB, the mobile station 3 performs call processing and connection establishment processing with the base station 2 by transmitting and receiving control signals in the C plane cell 5.

In operations AC and AD, the U-plane signal processing unit 41 of the base station 2 inserts a cell-specific reference signal and a synchronization signal into the radio signal transmitted by each

U-plane cell

6a and 6b. It shows how it is received. In operation AE, the U plane signal processing unit 21 of the mobile station 3 detects the reference signal corresponding to the identifier of the

U plane cells

6a and 6b notified by the cell notification information, and identifies the

U plane cells

6a and 6b. The U plane signal processing unit 21 performs symbol synchronization in the

U plane cells

6a and 6b.

In operation AF, the U plane signal processing unit 21 of the mobile station 3 measures the reception strength of the reference signal for each U plane cell 6. The application processing unit 24 of the mobile station 3 transmits an RRC protocol message for notifying cell quality information to the base station 2 in the C plane cell 5.

In operation AG, the communication control unit 42 of the base station 2 performs a scheduling process for determining the U-plane cell 6 and radio resources used for transmitting user traffic between the mobile station 3 and the base station 2a. In operation AH, the communication control unit 42 transmits scheduling information by PDCCH. Scheduling information is transmitted in the C plane cell 5. Here, it is assumed that the U-plane cell 6b is used for transmitting user traffic between the mobile station 3 and the base station 2a. User traffic is transmitted between the mobile station 3 and the base station 2a in the U-plane cell 6b designated by the scheduling information in operation AI.

<6. Operation during handover>
Next, the process at the time of HO of the mobile station 3 will be described. Even if the mobile station 3 moves between the U-plane cells 6, the mobile station 3 and the base station 2 do not perform the HO operation for changing the base station connected to the mobile station 3. The base station 2 changes the U plane cell 6 used for transmission of user traffic by changing the designation of the U plane cell 6 in the scheduling information.

For example, assume that the mobile station 3 moves from the U plane cell 6a to the U plane cell 6b as shown in FIG. When the mobile station 3 is in the U plane cell 6a, the reception strength in the U plane cell 6a is higher than the reception strength in the U plane cell 6b. However, when the mobile station 3 moves to the U plane cell 6b, the reception strength in the U plane cell 6b becomes higher than the reception strength in the U plane cell 6b. As a result, the base station 2 changes the cell specified by the scheduling information from the U plane cell 6a to the U plane cell 6b.

On the other hand, when the mobile station 3 moves between the C plane cells 5, the mobile station 3 and the base station 2 perform a HO operation to change the base station connected to the mobile station 3, and after the HO, the HO destination base station 2 The U plane cell 6 used for transmission of traffic between the mobile station 3 and the mobile station 3 is determined. FIG. 11 is an explanatory diagram of the operation at the time of HO between the C plane cells 5.

In operation BA, the HO source base station 2a controls measurement reports regarding mobility of the mobile station 3. Based on this control, the mobile station 3 reports the measurement result to the HO source base station 2a. In operation BB, the HO source base station 2a determines the HO destination candidate base station 2b. In operation BC, the HO source base station 2a transmits a HO request to the base station 2b. In operation BD, the base station 2b performs call admission control. When the call admission is permitted, the base station 2b becomes the HO-destination base station 2b.

In operation BE, the base station 2b returns a HO response to the HO request. In operation BF, the HO source base station 2a instructs the mobile station 3 to perform handover. In operation BG, synchronization processing of the physical layer and data link layer such as radio synchronization is executed between the mobile station 3 and the HO destination base station 2b to establish a connection.

In operation BH, the base station 2b transmits broadcast information via the BCCH. The broadcast information is transmitted in the C plane cell 5. The broadcast information transmitted at this time includes cell notification information related to the U-plane cell 6c formed by the base station 2b. The mobile station 3 receives cell notification information. Further, the mobile station 3 may acquire the cell notification information related to the U plane cell 6c from the BCCH during the connection establishment process in the operation BG.

Operation BI shows a state in which the mobile station 3 receives a signal obtained by inserting a cell-specific reference signal and a synchronization signal into a radio signal transmitted from the U-plane cell 6c by the base station 2b. In operation BJ, the mobile station 3 identifies the U plane cell 6c and performs symbol synchronization. In operation BK, the mobile station 3 measures the reception strength of the reference signal of the U plane cell 6c. The mobile station 3 transmits an RRC protocol message notifying cell quality information regarding the U plane cell 6 c to the base station 2 in the C plane cell 5.

Hereinafter, in the same manner as the operations AG to AI described with reference to FIG. 10, in operations BL to BM, scheduling of radio resources for user traffic and transmission of traffic using the U plane cell 6c are performed.

<7. Effect of Example>
According to this embodiment, the coverage range of the U plane cell 6 used for transmitting user traffic is made smaller than the coverage range of the C plane cell 5 used for transmitting control signals. As a result, the number of mobile stations 3 per U plane cell 6 can be reduced, and the radio resources that can be used by one mobile station 3 to transmit user traffic can be increased. Thereby, the traffic capacity of the entire network can be increased.

Further, by making the C plane cell 5 larger than the U plane cell 6, it is possible to avoid frequent HO processing even if the U plane cell 6 is downsized. For this reason, it is possible to avoid an increase in processing addition and radio resource consumption due to frequent occurrence of HO processing.

Also, by making the C plane cell 5 larger than the U plane cell 6, even if the U plane cell 6 that transmits user traffic is reduced, the decrease in the mobile stations 3 accommodated in the base station 2 is reduced. For this reason, it is possible to prevent excess control signal processing capability in the base station 2.

<8. Description of Modification>
Subsequently, a modification of the embodiment will be described. The U plane cell 6 may be formed so as to cover the entire C plane cell 5, and may be provided in a spot manner with priority given to a part of the C plane cell 5, for example, an area where user traffic is high. . The application processing unit 24 of the mobile station 3 does not transmit the cell quality information when the reference signal of the U plane cell 6 cannot be detected or when the reception strength is lower than the threshold value. Alternatively, the application processing unit 24 transmits empty cell quality information. When the cell quality information is not transmitted from a certain mobile station 3 or when the cell quality information is empty, the communication control unit 42 of the base station 2 assigns the radio resource of the radio signal transmitted in the C plane cell 5 to the mobile station 3. Allocate user traffic for transmission.

In another embodiment, the user traffic of the mobile station 3 located in the U plane cell 6 may be allocated from the radio resource of the C plane cell 5. Further, the user traffic of one mobile station 3 may be simultaneously allocated to the radio resources of the C plane cell 5 and the U plane cell 6. A part of the control signal may be transmitted by the U plane cell 6.

All examples and conditional terms contained herein are intended for educational purposes only to assist the reader in understanding the present invention and the concepts provided by the inventor for the advancement of technology. And should not be construed as being limited to the examples and conditions set forth above, as well as the configuration of the examples herein with respect to showing the superiority and inferiority of the present invention. Is. While embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions and modifications can be made thereto without departing from the spirit and scope of the present invention.

DESCRIPTION OF SYMBOLS 1

Communication system

2, 2a, 2b Base station apparatus 3

Mobile station apparatus

4, 4a-4c Radio |

wireless apparatus

5, 5a, 5b

C plane cell

6, 6a-6c U plane cell

Claims

A radio resource of a radio signal transmitted in the first cell is allocated to transmission of a control signal with the mobile station apparatus, and a radio resource of a radio signal transmitted in a second cell different from the first cell is assigned to the mobile station A scheduler assigned to transfer user traffic to and from the device;
A signal transmission / reception unit that transmits and receives control signals and user traffic to and from the mobile station apparatus according to radio resource allocation by the scheduler;
A base station apparatus comprising:
An identifier transmitter for transmitting the identifier of the second cell covered by the base station device in the first cell;
A signal transmission unit that transmits a radio signal in which a pattern signal unique to the second cell is inserted in the second cell;
A receiving unit for receiving a measurement result of the reception intensity of the pattern signal from the mobile station device;
The base station apparatus according to claim 1, wherein the scheduler determines a second cell to be used for transmission of user traffic according to the measurement result.
When the measurement result is not received from the mobile station apparatus, the scheduler allocates radio resources of radio signals transmitted in the first cell to user traffic transmission with the mobile station apparatus. The base station apparatus according to claim 2.
The base station apparatus according to any one of claims 1 to 3, further comprising a scrambler that scrambles user traffic to and from the mobile station apparatus using a code specific to the second cell.
A second cell different from the first cell used for transmission of user traffic to and from the base station apparatus from a radio signal transmitted in the first cell, and a second cell assigned for transmission of the user traffic A scheduling information detector that detects scheduling information that specifies radio resources of a radio signal to be transmitted;
A user traffic transmission / reception unit that transmits / receives the user traffic with a radio resource of a radio signal transmitted in the second cell specified by the scheduling information;
A mobile station apparatus comprising:
An identifier receiving unit that receives the identifier of the second cell covered by the base station apparatus in the first cell;
A measurement unit that detects a pattern signal specific to the second cell corresponding to the identifier from a radio signal transmitted by the base station device in a second cell, and measures the reception intensity of the pattern signal;
The mobile station apparatus according to claim 5, further comprising a measurement result transmission unit that transmits the measurement result of the reception intensity to the base station apparatus.
The mobile station apparatus according to claim 5 or 6, further comprising a scrambler that scrambles user traffic to and from the base station apparatus with a code specific to the second cell specified by the scheduling information.
8. The apparatus according to claim 5, further comprising a descrambler that descrambles a signal acquired from a radio resource designated by the scheduling information with a code specific to the second cell designated by the scheduling information. The mobile station apparatus as described in any one.
A communication system comprising a base station device and a mobile station device,
The base station device
The radio resource of the radio signal transmitted in the first cell is allocated to the transmission of the control signal with the mobile station apparatus, and the radio resource of the radio signal transmitted in the second cell different from the first cell is moved. A scheduler assigned to transmit user traffic to and from the station device;
A control signal transmission unit for transmitting, in the first cell, scheduling information specifying a radio resource allocated by the scheduler for transmission of the user traffic and a second cell used for transmission of the user traffic;
A user traffic transmission / reception unit that transmits / receives user traffic to / from the mobile station apparatus according to radio resource allocation by the scheduler,
The mobile station device
A scheduling information detector for detecting the scheduling information from a radio signal transmitted in the first cell;
A user traffic transmission / reception unit that transmits / receives the user traffic with a radio resource of a radio signal transmitted in the second cell specified by the scheduling information;
A communication system comprising:
Allocating radio resources of radio signals transmitted in the first cell for transmission of control signals between the base station apparatus and the mobile station apparatus,
A communication method, comprising: allocating radio resources of radio signals transmitted in a second cell different from the first cell for transmission of user traffic between the base station apparatus and the mobile station apparatus.
Transmitting the identifier of the second cell covered by the base station apparatus in the first cell;
A radio signal in which a pattern signal unique to the second cell is inserted is transmitted from the base station apparatus in the second cell,
Measure the reception intensity of the pattern signal in the mobile station device,
The communication method according to claim 10, wherein a second cell to be used for transmission of user traffic is determined according to a measurement result of the reception strength.
The communication method according to claim 11, wherein when the pattern signal is not received by the mobile station apparatus, radio resources of radio signals transmitted in the first cell are allocated for transmission of user traffic.
The communication according to claim 11, wherein when the mobile station apparatus is not in any of the second cells, radio resources of radio signals transmitted in the first cell are allocated for transmission of user traffic. Method.
The communication method according to any one of claims 10 to 13, wherein user traffic to and from the base station apparatus is scrambled with a code unique to the second cell.