WO2012074048A1 - Wireless communication path selection method, wireless communication system and control device - Google Patents

Abstract

The present invention is a wireless communication path selection method in a control device for controlling communication among a base station device, a mobile station device, and relay station devices for relaying communication between the base station device and the mobile station device, wherein a control device calculates scores related to communication qualities of a first transport path which performs communication with the base station device and the mobile station device without going through the relay devices and a second transport path which performs communication from the base station device through the relay devices to the mobile station device, whereupon the control device, on the basis of the scores, selects a first candidate from between the first and second transport paths, and the control device, on the basis of the scores, selects a second candidate other than the first candidate from between the first and second transport paths.

Description

Wireless communication path selection method, wireless communication system, and control apparatus

The present invention relates to a wireless communication path selection method, a wireless communication system, and a control device.
This application claims priority based on Japanese Patent Application No. 2010-269711 filed in Japan on December 2, 2010, the contents of which are incorporated herein by reference.

In recent wireless communication systems, new multimedia data communication services such as an Internet connection function, a music distribution function, a video distribution function, and an electronic payment function have been developed as compared with conventional communication systems only for calls. In such a wireless system, higher communication quality is required. In addition, since the transmission power of the mobile station apparatus is limited by restrictions such as power supply capacity, it is difficult to expand the radio area covered by one base station apparatus.

On the other hand, in Patent Document 1, the following processing is performed for the purpose of expanding the communication service area and improving communication quality. In other words, when the relay station device is placed in the far end of the communication service area or in the radio wave insensitive zone and wireless communication is performed between the transmitting station and the receiving station via relay communication, the relay station device receives the signal from the transmitting station. The communication data error is detected based on the control information. Thereby, the transfer of the data block in which the error is detected to the receiving station is suppressed.

In Patent Document 2, the following processing is performed in a wireless communication system between a base station device and a mobile station device via a relay station device. In other words, when determining whether to communicate via the transmission path between the mobile station device and the base station device or via the relay station device, the used frequency band, transmission time, propagation loss value, propagation loss fluctuation value width, relative movement The evaluation value of each route is calculated from the information on the speed and the transmission power value, and the route is selected based on the evaluation value.

JP 2008-60951 A JP 2010-232945 A

However, with the techniques described in Patent Documents 1 and 2, if a communication failure occurs between the base station device and the relay station device, communication cannot be resumed immediately.

The present invention has been made in view of the above problems, and a wireless communication path selection method and a wireless communication system capable of wireless communication even when a communication failure occurs between a base station device and a relay station device And a control device.

(1) The present invention has been made to solve the above-described problem, and a wireless communication path selection method according to the first aspect of the present invention includes a base station device, a mobile station device, and the base station device. And a relay station device that relays communication between the mobile station device and a wireless communication path selection method in a control device that controls communication between the base station device and the mobile station device. Calculating an evaluation value related to communication quality of a first transmission path that performs communication without passing through the base station apparatus and a second transmission path that performs communication from the base station apparatus to the mobile station apparatus via the relay station apparatus, A first candidate is selected from the first and second transmission paths based on the evaluation value, and the first candidate is selected from the first and second transmission paths based on the evaluation value. A second candidate other than the candidate is selected.

(2) In the wireless communication path selection method according to the first aspect of the present invention, when the first candidate transmission path is a transmission path via the relay station device, the evaluation value is used. The second candidate may be selected from the first and second transmission paths.

(3) The wireless communication system according to the second aspect of the present invention includes a base station device, a mobile station device, a relay station device that relays communication between the base station device and the mobile station device, and system control. A wireless communication system including a control device for performing a communication between the base station device and a mobile station device without passing through the relay station device, and the base station device. A calculation unit that calculates an evaluation value related to communication quality of a second transmission path that communicates with the mobile station apparatus via the relay station apparatus; and the first and second transmission paths based on the evaluation value And a selection unit that selects a second candidate other than the first candidate from the first and second transmission paths based on the evaluation value. .

(4) Note that, in the wireless communication system according to the second aspect of the present invention, the selection unit is configured such that when the first candidate transmission path is a transmission path through the relay station device, the first candidate The second candidate may be selected from a communicable transmission path other than the candidate transmission path.

(5) Also, in the radio communication system according to the second aspect of the present invention, the control device may be included in the base station device.

(6) Moreover, in the wireless communication system according to the second aspect of the present invention, the control device may include a notification unit that notifies the relay station device of the second candidate.

(7) Moreover, the radio | wireless communications system by the 2nd aspect of this invention WHEREIN: The said control apparatus may be provided with the notification part which notifies the said 2nd candidate to the said mobile station apparatus.

(8) Also, in the wireless communication system according to the second aspect of the present invention, when the control device is requested to notify the second candidate from the relay station device, the control device determines the second candidate. You may provide the notification part which notifies to the said relay station apparatus.

(9) Also, in the wireless communication system according to the second aspect of the present invention, when the control device is requested to notify the second candidate from the mobile station device, the control device determines the second candidate. You may provide the notification part which notifies to the said mobile station apparatus.

(10) The control device according to the third aspect of the present invention includes a base station device, a mobile station device, a relay station device that relays communication between the base station device and the mobile station device, and system control. A control device that performs communication between the base station device and the mobile station device without passing through the relay station device, and the mobile station device through the relay station device from the base station device A calculation unit that calculates an evaluation value related to communication quality of a second transmission path that performs communication with the station device, and a first candidate is selected from the first and second transmission paths based on the evaluation value And a selection unit that selects a second candidate other than the first candidate from the first and second transmission paths based on the evaluation value.

According to the present invention, when a communication failure occurs between the base station apparatus and the relay station apparatus, the communication path can be immediately changed to a communicable communication path.

1 is a conceptual diagram of a wireless communication system according to an embodiment of the present invention. It is a schematic block diagram which shows the structure of the base station apparatus which concerns on this embodiment. It is a schematic block diagram which shows the structure of the relay station apparatus which concerns on this embodiment. It is a flowchart which shows operation | movement of the path | route selection part of the relay station apparatus which concerns on this embodiment. It is a schematic block diagram which shows the structure of the mobile station apparatus which concerns on this embodiment. In the radio | wireless communications system which concerns on this embodiment, it is a sequence diagram which shows an example in the case of route selection using a downlink transmission path quality value. It is a sequence diagram which shows an example when a failure generate | occur | produces in communication between the base station apparatus and relay station apparatus which concern on this embodiment. It is a sequence diagram which shows the modification when a failure generate | occur | produces in the communication between the base station apparatus and relay station apparatus which concern on this embodiment.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing a wireless communication system according to an embodiment of the present invention.
The radio communication system of FIG. 1 includes a base station device 2, relay station devices 3-1, 3-2, and a mobile station device 4. In the present embodiment, the case where the number of base station devices is 1, the number of relay station devices is 2, and the number of mobile station devices is 1, but this is an example, and the present invention is not limited to this. . In FIG. 1, the base station apparatus 2 establishes a transmission path for wireless communication with the relay station apparatuses 3-1 and 3-2 and the mobile station apparatus 4.
The relay station apparatuses 3-1 and 3-2 are installed in a place far away from the base station apparatus 2 or in a radio wave insensitive zone, and are used for expanding the communication service area of the base station apparatus 2 and improving communication quality. The mobile station device 4 is a movable communication terminal used by a user. Examples of the communication terminal include a mobile phone, a PC (personal computer) having a communication function, and a PDA (personal digital assistant).

Here, the transmission path between the base station apparatus 2 and the relay station apparatuses 3-1 and 3-2 and the mobile station apparatus 4 will be described. In the present embodiment, the following three paths (transmission paths) exist between the base station apparatus 2 and the mobile station apparatus 4.

Path R1: base station device 2 → mobile station device 4,
Path R2: base station device 2 → relay station device 3-1, mobile station device 4,
Path R3: base station device 2 → relay station device 3-2 → mobile station device 4

That is, the route R1 is a route for performing communication directly from the base station device 2 to the mobile station device 4. The route R1 includes one transmission line (transmission line P1). The routes R2 and R3 are routes that are relayed from the base station device 2 by one relay station device 3-1, 3-2 and communicate with the mobile station device 4.
The path R2 includes a transmission path (transmission path P2) between the base station apparatus 2 and the relay station apparatus 3-1, and a transmission path (transmission path P3) between the relay station apparatus 3-1 and the mobile station apparatus 4. Including two transmission lines.
The path R3 includes a transmission path (transmission path P4) between the base station apparatus 2 and the relay station apparatus 3-2, and a transmission path (transmission path P5) between the relay station apparatus 3-2 and the mobile station apparatus 4. Including two transmission lines.
A transmission path used when the base station apparatus 2 and the relay station apparatuses 3-1 and 3-2 are connected by wireless communication is called a backhaul link. A transmission path used when the relay station apparatuses 3-1 and 3-2 and the mobile station apparatus 4 are connected by wireless communication is called an access link.

These transmission paths are used for upstream and downstream communications of the transmission paths P1 to P5. The uplink and downlink transmission channel quality of one transmission channel is almost in the state of quality, but the quality actually differs because of the difference in the frequency band used and the traffic situation.
Here, a case will be described in which a transmission path quality value is evaluated for a downlink transmission path, and which path is used using the transmission path quality value. Note that the same can be applied to the case of evaluating the transmission path quality value for the upstream transmission path and determining the path.
When any of the first, second, and third routes can be used, the base station device 2 calculates an evaluation value of each route using each transmission channel quality value, and selects a route with a good evaluation value. . Here, in order to simplify the description, an example is shown in which the base station apparatus 2 selects one of the first, second, and third paths. However, when there are more base station devices and relay station devices with which the mobile station device can communicate than in the example shown in the present embodiment, a larger number of routes may be selected. Hereinafter, the downlink of the transmission path is referred to as a downlink transmission path, and the uplink of the transmission path is referred to as an uplink transmission path.

The mobile station apparatus 4 receives and demodulates the reference signal transmitted from the base station apparatus 2 in order to measure the transmission path quality value of the downlink transmission path P1. The mobile station apparatus 4 measures the received power from the demodulated amplitude value of the reference signal, and measures the noise power by obtaining the variance value of the received signal. The mobile station device 4 measures the SNR (Signal-Noise-Ratio) by calculating the ratio between the received power and the noise power.
The mobile station apparatus 4 receives the reference signals transmitted from the relay station apparatus 3-1 and the relay station apparatus 3-2 in order to measure the transmission path quality values of the downlink transmission path P3 and the downlink transmission path P5. Demodulate. The mobile station device 4 measures received power from the demodulated amplitude value of the reference signal, and obtains a dispersion value of the received signal based on the measured received power, thereby measuring noise power. The mobile station apparatus 4 measures the SNR by calculating the ratio between the received power and the noise power.

Relay station apparatuses 3-1 and 3-2 receive and demodulate the reference signal transmitted from base station apparatus 2 in order to measure the communication quality of downlink transmission paths P2 and P4. Relay station apparatuses 3-1 and 3-2 measure the received power from the amplitude value of the demodulated reference signal, and obtain the dispersion value of the received signal, thereby measuring the noise power. The relay station apparatuses 3-1 and 3-2 measure the SNR by calculating the ratio of the received power and the noise power.

In addition to the above SNR, it is possible to use a frequency bandwidth to be used, a required time, a propagation loss value, a propagation loss fluctuation range, an average received power, and the like as the transmission path quality value.
The frequency band corresponds to the frequency bandwidth used in the transmission path. When transmitting the same amount of information, if the frequency bandwidth used is small, it means that the quality of the transmission path is good.
The required time can be obtained by actually measuring the time for transmitting the prescribed amount of data on the transmission line.
The transmission loss value is obtained by subtracting the reception power value from the transmission power value of the reference signal, thereby obtaining the transmission loss value (also referred to as “path loss”) of the transmission line.
The transmission loss fluctuation range is obtained by integrating the dispersion value of the propagation path loss value over a unit time.
The average received power corresponds to a value obtained by averaging the signal level measured when the reference signal is received for the unit time. For example, the reciprocal of the average received power can be used as the transmission path quality value.
The mobile station device 4 and the relay station devices 3-1 and 3-2 use the transmission path quality value measured or set as described above (for example, “frequency band to be used” is set). Transmit to the base station apparatus 2. The transmission path quality values transmitted by the mobile station device 4 and the relay station devices 3-1 and 3-2 are used for route selection by the base station device 2.

FIG. 2 is a schematic block diagram showing the configuration of the base station apparatus 2 according to one embodiment of the present invention.
The base station device 2 includes a control device 2-1, a receiving unit 201, a transmitting unit 209, and an antenna 210. The control device 2-1 includes a transmission path quality reception unit 202, an evaluation value calculation unit 203, a route selection unit 204, a reference signal generation unit 205, a connection change unit 206, a relay operation instruction unit 207, a quality evaluation transmission unit 208, a path quality A request receiving unit 211, a control unit 212, and a storage unit 213 are provided. In addition, the base station apparatus 2 has other generally known functions of the base station apparatus related to transmission / reception of data signals.
The receiving unit 201 converts the frequency of the radio signal received by the antenna 210 into a baseband signal, performs demodulation and decoding operations, and then transmits a control signal such as a propagation path quality value to the transmission path quality receiving unit 202 and the path. Output to the quality request receiver 211.

The transmission path quality receiving unit 202 acquires the transmission path quality values of the transmission paths P1 to P5 from the receiving unit 201. The transmission path quality reception unit 202 outputs each transmission path quality value to the evaluation value calculation unit 203.
Evaluation value calculation section 203 calculates an evaluation value for each path based on the transmission path quality values of transmission paths P1 to P5 input from transmission path quality reception section 202. For example, the evaluation values of the paths R1 to R3 may be the sum of the transmission path quality values of the transmission paths included in each path. The evaluation value calculation unit 203 generates route evaluation value information. The route evaluation value information is information in which route ID information for distinguishing the routes R1 to R3, the evaluation value, and relay presence / absence information indicating whether or not the route passes through the base station apparatus are associated with each other. The evaluation value calculation unit 203 outputs route evaluation value information to the route selection unit 204.
The route selection unit 204 selects the route ID and the relay presence / absence information of the route (first candidate) having the smallest route evaluation value from the route evaluation value information input from the evaluation value calculation unit 203. When the selected relay presence / absence information indicates that the selected relay presence / absence information is via the relay station device (relay station), the route selection unit 204 determines the second smallest route from the evaluation value information of the route input from the evaluation value calculation unit 203. A route ID having (second candidate) is selected. The route selection unit 204 outputs the selected route information indicating the extracted route ID to the connection change unit 206 and the quality evaluation transmission unit 208.

FIG. 3 is a flowchart showing an example of the operation of the route selection unit 204 (FIG. 2) of the base station apparatus 2. The operation of the route selection unit 204 will be described in detail with reference to this flowchart.

(Step S301)
The route selection unit 204 selects the route having the first smallest evaluation value from the route evaluation value information input from the evaluation value calculation unit 203. Thereafter, the process proceeds to step S302.

(Step S302)
The route selection unit 204 determines whether or not the route having the first smallest evaluation value selected in step S301 is via the relay station device based on the relay presence / absence information. If it is determined that the relay station device is not passed (YES), the process proceeds to step S303. If it is determined that the relay station device is used (NO), the process proceeds to step S304.

(Step S303)
The route selection unit 204 includes the route ID corresponding to the route that is the evaluation value information output from the evaluation calculation unit 203 and is determined based on the evaluation value information of the route and has the first smallest evaluation value. Select path information is generated. Thereafter, the process proceeds to an end process.

(Step S304)
The route selection unit 204 selects a route having the second smallest evaluation value from the route evaluation values input from the evaluation value calculation unit 203. Thereafter, the process proceeds to step S302.

(Step S305)
The route selection unit 204 is the evaluation value information output from the evaluation calculation unit 203 and is a route determined based on the evaluation value information of the route, and the first smallest evaluation value, the second smallest evaluation value, The selected route information including the route ID corresponding to the route having is generated. Thereafter, the process proceeds to an end process.

As described above, the route determination unit 204 includes the route ID corresponding to the route having the first smallest evaluation value and the second smallest evaluation value when the selected route passes through the relay station device. The selected route information is output to the connection changing unit 206 and the quality evaluation transmitting unit 208. On the other hand, when the selected route does not go through the relay station device, the route determination unit 204 sends the selected route information including only the route ID corresponding to the first smallest evaluation value to the connection changing unit 206 and the quality evaluation transmission. To the unit 208.
The reference signal generation unit 205 receives an instruction from the control unit 212 to generate a reference signal for measurement of transmission path quality values of the transmission paths P1, P2, and P4. Here, the reference signal is a signal whose waveform is defined in advance by the base station device, the relay station device, and the mobile station device, and is used for determination of transmission path quality. The reference signal generation unit 205 generates a reference signal for measuring transmission path quality values of the transmission paths P1, P2, and P4. The reference signal includes information indicating that the transmission source is the base station apparatus 2. The reference signal generation unit 205 outputs the generated reference signal to the transmission unit 209.

The connection change unit 206 is a relay station device 3-1, 3-2 and mobile station device when the selected route information output from the route selection unit 204 is changed and the route needs to be changed. 4 generates information for instructing a route change. The connection change unit 206 outputs information related to the change of the route to the transmission unit 209.
The control unit 212 estimates a relay station device located in the vicinity of the mobile station device 4, and outputs a command to the relay operation instruction unit 207 to cause the relay station device to perform a relay operation. Relay operation instructing unit 207 generates a signal including a command for causing the relay station device to perform a relay operation, and outputs the signal to transmitting unit 209.
The quality evaluation transmission unit 208 transmits the selected route information input from the route selection unit 204 to the relay station devices 3-1 and 3-2 and the mobile station device 4 via the transmission unit 209. When the instruction to transmit the selected route information is input from the route quality request receiving unit 211, the quality evaluation transmitting unit 208 acquires the selected route information from the selected route selecting unit 204, and via the transmitting unit 209, The data is transmitted to relay station apparatuses 3-1 and 3-2 and mobile station apparatus 4.

The transmission unit 209 acquires the above-described information and signals from the reference signal generation unit 205, the connection change unit 206, the relay operation instruction unit 207, and the quality evaluation transmission unit 208. The transmission unit 209 generates a baseband signal through operations of encoding and modulation of the input information and signal, and converts the frequency of the baseband signal into a radio signal. Transmitter 209 outputs the frequency-converted radio signal to antenna 210.
The antenna 210 transmits the radio signal output from the transmission unit 209 as a radio wave to the relay station apparatuses 3-1 and 3-2 and the mobile station apparatus 4.
The route quality request receiving unit 211 receives a request signal for requesting transmission of the selected route information from the relay station devices 3-1 and 3-2 and the mobile station device 4 via the receiving unit 201, and transmits the selected route information. The instruction to be output is output to the quality evaluation transmission unit 208.
The control unit 212 outputs a command for generating a reference signal to the reference signal generation unit 205. The control unit 212 commands the relay operation instruction unit 207 to transmit a command to the relay station devices 3-1 and 3-2 to perform the relay operation.
In the storage unit 213, the evaluation value calculation unit 203 writes or reads the device ID, relay presence / absence information, and the like.

FIG. 4 is a schematic block diagram showing the configuration of the relay station apparatus 3-1 according to the embodiment of the present invention. The relay station device 3-2 has the same configuration as the relay station device 3-1.
The relay station device 3-1 includes a reception unit 301, a reference signal power measurement unit 302, an SNR measurement unit 303, a relay operation management unit 304, a reference signal generation unit 305, a location registration information generation unit 306, a path quality transmission unit 307, a transmission A path loss transmission unit 308, a communication disconnection determination unit 309, a communication disconnection occurrence notification unit 310, a transmission unit 311, an antenna 312, a path quality request unit 313, a control unit 314, and a storage unit 315 are provided. In addition, the relay station apparatus 3-1 has other generally known functions of the relay station apparatus related to transmission / reception of data signals.
The receiving unit 301 converts the radio signal received by the antenna 312 into a received signal. The receiving unit 301 converts the frequency of the received signal into a baseband signal. The receiving unit 301 performs frequency conversion, demodulation and decoding operations on the baseband signal, and then transmits a control signal such as a channel quality value, a reference signal power measurement unit 302, a relay operation management unit 304, and position registration information. The data is output to the generation unit 306, the path quality transmission unit 307, the transmission path quality transmission unit 308, the communication disconnection determination unit 309, and the storage unit 315.

The reference signal power measurement unit 302 acquires the reference signal transmitted by the base station apparatus 2 via the reception unit 302, and measures the power based on the amplitude value of the reference signal. The reference signal power measurement unit 302 outputs the measured reference signal power (referred to as “reception power”) to the SNR measurement unit 303.
The SNR measurement unit 303 acquires received power from the reference signal power measurement unit 302. The SNR measurement unit 303 measures noise power by obtaining a dispersion value of received power. SNR measurement section 303 calculates the ratio (SNR) between received power and noise power, and outputs the ratio to position registration information generation section 306 and transmission path quality transmission section 308.

The relay operation management unit 304 receives the route change completion notification transmitted from the mobile station device 4, and transmits this route change completion notification to the base station device 2 via the transmission unit 311.
The reference signal generation unit 305 acquires a command for generating a reference signal from the control unit 314, and generates a reference signal for measuring the transmission path quality value of the transmission path P3. This reference signal includes information indicating that the transmission source is the relay station device 3-1. The reference signal generation unit 305 outputs the generated reference signal to the transmission unit 311.
Location registration information generation section 306 selects the transmission path with the first highest transmission path quality value based on the SNR output from SNR measurement section 303. The location registration information generation unit 306 generates information for performing location registration in the base station apparatus corresponding to the transmission channel having the first highest transmission channel quality value, and outputs the information to the transmission unit 309.

The route quality transmission unit 307 acquires, from the reception unit 301, information on the route selected by the base station apparatus 2, the route having the first smallest evaluation value, and the route having the second smallest evaluation value, and transmits the information. To the unit 311.
The transmission path quality transmission unit 308 performs transmission path loss between the base station apparatus 2 and the mobile station apparatus 4 (transmission path P1) and between the relay station apparatus 3-1 and the mobile station apparatus 4 (transmission path P3). And acquired via the receiving unit 301. The transmission path quality transmission unit 308 acquires the transmission path loss between the base station apparatus 2 and the relay station apparatus 3-1 (transmission path P2) from the SNR measurement unit 303. The transmission path quality transmission unit 308 outputs the transmission path quality values of the transmission paths P 1, P 2, and P 3 to the transmission unit 311.
The communication disconnection determination unit 309 determines whether communication between the base station device 2 and the relay station device 3-1 has been interrupted based on the input from the reception unit 301. For example, the determination criterion is whether or not the number of packet communication errors between the base station device 2 and the relay station device 3-1 exceeds a certain value. If the communication disconnection determination unit 309 determines that communication between the base station device 2 and the relay station device 3-1 has been interrupted, the communication disconnection determination unit 309 transmits a signal indicating that a communication failure (RLF: Radio Link Failure) has occurred. Output to the occurrence notification unit 310.
The communication disconnection occurrence notification unit 310 receives a signal indicating that an RLF has occurred from the communication disconnection determination unit 309, receives input of selected route information from the storage unit 315, and outputs an RLF generation notification to the transmission unit 311. Further, the communication disconnection occurrence notification unit 310 receives a signal indicating that an RLF has occurred from the communication disconnection determination unit 309, receives input of selected route information from the storage unit 315, and outputs a communication path change notification to the transmission unit 311. To do.

The transmission unit 311 includes a relay operation management unit 304, a reference signal generation unit 305, a location registration information generation unit 306, a path quality transmission unit 307, a transmission path quality transmission unit 308, a path quality request unit 313, and a communication disconnection occurrence notification unit 310. Get the signal.
The transmission unit 311 generates a baseband signal through an operation of encoding / modulating the input information and signal, and converts the frequency of the baseband signal into a radio signal. Transmitter 311 outputs the radio signal subjected to frequency conversion to antenna 312.
The antenna 312 transmits the radio signal output from the transmission unit 311 as a radio wave from the relay station device 3-1 to the base station device 2 and the mobile station device 4.
The route quality request unit 313 receives an input from the control unit 314, and transmits a command for causing the base station apparatus 2 to transmit the selected route information via the transmission unit 311.
The control unit 314 outputs a command for generating a reference signal to the reference signal generation unit 305. The control unit 314 outputs a command for transmitting the selected route information to the route quality request unit 313.
The storage unit 315 stores the selected route information input from the receiving unit 301. The storage unit 315 outputs the selected route information to the communication disconnection occurrence notification unit 310.

FIG. 5 is a schematic block diagram showing the configuration of the mobile station apparatus 4 according to one embodiment of the present invention.
The mobile station apparatus 4 includes a receiving unit 401, a reference signal power measuring unit 402, an SNR measuring unit 403, a storage unit 404, a path changing unit 405, a transmission path quality transmitting unit 406, a location registration information generating unit 407, a transmitting unit 408, an antenna. 409, a route quality request unit 410 and a control unit 411. In addition, the mobile station apparatus 4 has other generally known functions of the mobile station apparatus related to transmission / reception of data signals.

The reception unit 401 converts the frequency of the radio signal received by the antenna 409 into a baseband signal, performs demodulation and decoding operations, and then transmits the reference signal and the like to the reference signal power measurement unit 402, the storage unit 404, and the path The data is output to the changing unit 405.
The reference signal power measurement unit 402 acquires the reference signal transmitted from the base station device 2 and the relay station devices 3-1 and 3-2 from the reception unit 401, and measures the power based on the amplitude value of the reference signal. The reference signal power measurement unit 402 outputs the measured reference signal power (reception power) to the SNR measurement unit 403.
The SNR measurement unit 403 acquires received power from the reference signal power measurement unit 402. The SNR measurement unit 403 measures noise power by obtaining a dispersion value of received power. SNR measurement section 403 calculates the ratio (SNR) between received power and noise power, and outputs the ratio to transmission path quality transmission section 406 and location registration information generation section 407.

The storage unit 404 acquires and stores information regarding the route having the first smallest evaluation value and the route having the second smallest evaluation value generated by the route selection unit 204 of the base station device 2.
The storage unit 404 outputs to the route changing unit 405 information related to the route with the first smallest evaluation value and the route with the second smallest evaluation value.
The route changing unit 405 acquires information on the route change output from the base station device 2 from the storage unit 404. The route changing unit 405 acquires information on the route having the first smallest evaluation value and the route having the second smallest evaluation value from the storage unit 404. The path changing unit 405 reads out an RLF occurrence notification, a communication path change notification, and a communication path change request from the storage unit 404. Then, the route changing unit 405 performs communication with the base station device 2, the relay station device 3-1 or 3-2 based on the information about the route with the first smallest evaluation value and the route with the second smallest evaluation value. A signal for starting the connection procedure is output to the transmission unit 408.

The transmission path quality transmission unit 406 acquires the transmission path loss between the base station apparatus 2 and the mobile station apparatus 4 (transmission path P1) from the SNR measurement unit 403. The transmission path quality transmission unit 406 acquires the transmission path loss between the relay station apparatuses 3-1 and 3-2 and the mobile station apparatus 4 (transmission paths P 3 and P 5) from the SNR measurement unit 403. Transmission path quality transmission section 406 outputs the transmission path quality of transmission paths P 1, P 3 and P 5 to transmission section 408.
The location registration information generation unit 407 selects the transmission path with the first highest transmission path quality value based on the SNR output from the SNR measurement section 403. The location registration information generation unit 407 generates information for performing location registration in the base station device 2, the relay station device 3-1 or 3-2 corresponding to the transmission channel having the first highest transmission channel quality value, The data is output to the transmission unit 408.
The transmission unit 408 acquires signals from the path change unit 405, the transmission path quality transmission unit 406, the location registration information generation unit 407, and the path quality request unit 410. The transmission unit 408 encodes and modulates the signal and information input in this manner to generate a baseband signal, and converts the frequency of the baseband signal into a radio signal. Transmitter 408 outputs the frequency-converted radio signal to antenna 409.
The antenna 409 transmits the radio signal input from the transmission unit 408 as a radio wave to the relay station apparatuses 3-1 and 3-2 and the base station apparatus 2.
The route quality request unit 410 receives an input from the control unit 411 and transmits a command for causing the base station apparatus 2 to transmit the selected route information via the transmission unit 408.
The control unit 411 outputs a command for causing the route quality request unit 410 to transmit the selected route information.

Hereinafter, an embodiment of the present invention will be described with reference to a sequence diagram.
FIG. 6 is a sequence diagram illustrating an example of processing for performing route selection based on downlink transmission path quality measurement according to an embodiment of the present invention. Note that it is possible to perform route selection in the same manner based on uplink transmission channel quality measurement. Here, a change process from the route R1 to the route R2 is shown. Here, as shown in FIG. 1, a case where there is one base station apparatus 2, two relay station apparatuses (3-1, 3-2), and one mobile station apparatus 4 will be described.

(Step S501)
The base station apparatus 2 transmits the reference signal generated by the reference signal generation unit 205 to the relay station apparatus 3-1 (transmission path P2). The relay station device 3-1 transmits the reference signal generated by the reference signal generation unit 305 to the mobile station device 4 (transmission path P3).
The base station apparatus 2 transmits the reference signal generated by the reference signal generation unit 205 to the relay station apparatus 3-2 (transmission path P4). The relay station apparatus 3-2 transmits the reference signal generated by the reference signal generation unit 305 to the mobile station apparatus 4 (transmission path P5).

(Step S502)
The location registration information generation unit 306 of the relay station device 3-1 uses the transmission line quality value output from the SNR measurement unit 303 as the transmission line having the highest transmission line quality value (here, transmission line P 2). The corresponding base station apparatus is selected and location registration is performed.
Based on the transmission path quality value output from the SNR measurement section 303, the location registration information generation section 306 of the relay station apparatus 3-2 sets the transmission path having the highest transmission path quality value (here, transmission path P4). The corresponding base station apparatus is selected and location registration is performed.

(Step S503)
The relay station device 3-1 receives the reference signal transmitted from the base station device 2, measures the reference signal power in the reference signal power measurement unit 302, and outputs the measured power to the SNR measurement unit 303. The SNR measurement unit 303 outputs the calculated SNR to the transmission path quality transmission unit 308. The transmission path quality transmission unit 308 transmits the transmission path quality value of the downlink transmission path P2 to the base station apparatus 2.
The relay station device 3-2 receives the reference signal transmitted from the base station device 2, measures the power of the reference signal by the reference signal power measurement unit 302, and outputs the measured power to the SNR measurement unit 303. The SNR measurement unit 303 outputs the calculated SNR to the transmission path quality transmission unit 308. The transmission path quality transmission unit 308 transmits the transmission path quality value of the downlink transmission path P4 to the base station apparatus 2. The operation in step S503 is continuously performed periodically.

(Step S504)
The location registration information generation unit 407 of the mobile station apparatus 4 is based on the transmission path quality values of the paths R1, R3, and R5 output from the SNR measurement unit 403, and the base corresponding to the transmission path with the first highest transmission path quality value is provided. Location registration is performed by selecting a station device or a relay station device (here, the base station device 2).

(Step S505)
The base station apparatus 2 and the mobile station apparatus 4 start a connection procedure by calling or receiving each other, and start communication between the base station apparatus 2 and the mobile station apparatus 4 via the path R1.

(Step S506)
The mobile station device 4 receives the reference signal transmitted from the base station device 2, measures the power of the reference signal by the reference signal power measurement unit 402, and outputs the measured power to the SNR measurement unit 403. SNR measuring section 403 outputs the calculated SNR to transmission path quality transmitting section 406. The transmission path quality transmission unit 406 transmits the transmission path quality value of the downlink transmission path P1 to the base station apparatus 2. The operation in step S506 is continuously performed periodically.

(Step S507)
The base station device 2 estimates the relay station devices 3-1 and 3-2 located in the vicinity of the mobile station device 4. Specifically, the relay operation instruction unit 207 of the base station device 2 transmits a command to start the relay operation to the relay station devices 3-1 and 3-2 located in the vicinity of the mobile station device 4. . The relay station devices 3-1 and 3-2 receive an instruction to start the relay operation from the base station device 2 and start the relay operation. Note that the relay station devices 3-1 and 3-2 do not perform the relay operation only when receiving a command to start the relay operation, but may always perform the relay operation. In this case, the base station device 2 does not need to transmit a command to start the relay operation. Note that the relay station devices 3-1 and 3-2 located in the vicinity of the mobile station device 4 may make the determination based on the information on the position registration already performed. Alternatively, the relay station devices 3-1 and 3-2 located in the vicinity may be determined by transmitting location registration information from the mobile station device 4 again.

(Step S508)
The relay station apparatuses 3-1 and 3-2 transmit the reference signal generated by the reference signal generation unit 305 to the mobile station apparatus 4.

(Step S509)
The mobile station device 4 receives the reference signals transmitted from the relay station devices 3-1 and 3-2, measures the reference signal power by the reference signal power measurement unit 402, and sends the measured power to the SNR measurement unit 403. Output. The SNR measurement unit 303 outputs the calculated SNR to the transmission path quality transmission unit 308. The transmission path quality transmission unit 308 transmits the transmission path quality values of the downlink transmission paths P3 and P5 to the base station apparatus 2 via the path R1. The operation in step S509 is continuously performed periodically.

(Step S510)
The receiving unit 201 of the base station apparatus 2 receives the transmission path quality value of each transmission path transmitted from the relay station apparatuses 3-1 and 3-2 and the mobile station apparatus 4 and outputs it to the transmission path quality receiving unit 202. . The transmission path quality reception unit 202 outputs the transmission path quality value of each transmission path to the evaluation value calculation unit 203. The evaluation value calculation unit 203 is based on each transmission path quality value input from the transmission path quality reception unit 202, and is an E _{path R1} , E _{path R2} , which is an evaluation value (path evaluation value) of the paths R1, R2, R3, E _{route R3} is calculated. The evaluation value calculation unit 203 outputs route evaluation value information to the route selection unit 204.
The route selection unit 204 determines that the route having the first smallest evaluation value is the route via the relay station device 3-1 from the route evaluation value information input from the evaluation value calculation unit 203. Selected route information including a route ID corresponding to a route having a small evaluation value and a second smallest evaluation value is generated. The route selection unit 204 outputs the selected route information to the connection change unit 206 and the quality evaluation transmission unit 208.

(Step S511)
The base station apparatus 2 transmits the selected path information calculated by the evaluation value calculation unit 204 in step S510 to the relay station apparatuses 3-1 and 3-2 (path evaluation result report). At this time, not only the path having the smallest evaluation value but also a path that is a candidate for RLF recovery used when RLF occurs between the base station apparatus 2 and the relay station apparatuses 3-1 and 3-2 ( 2nd route with the smallest evaluation value) is also transmitted. Note that the route quality request unit 313 of the relay station devices 3-1 and 3-2 may send a route evaluation result report transmission request to the route quality request reception unit 211 of the base station device 2. In this case, the route quality request reception unit 211 of the base station apparatus 2 instructs the quality evaluation transmission unit 208 to transmit the route evaluation result report, and the quality evaluation transmission unit 208 transmits the route evaluation result report via the transmission unit 209. Send.

(Step S512)
The base station apparatus 2 reports a path evaluation result to the mobile station apparatus 4 via the quality evaluation transmission unit 208. At this time, not only the route having the smallest evaluation value but also a route that becomes a candidate route for RLF recovery when an RLF occurs between the base station device 2 and the relay station devices 3-1 and 3-2. Send. Note that the route quality request unit 410 of the mobile station device 4 may make a transmission request for a route evaluation result report to the route quality request reception unit 211 of the base station device 2. In this case, the route quality request reception unit 211 of the base station apparatus 2 instructs the quality evaluation transmission unit 208 to transmit the route evaluation result report, and the quality evaluation transmission unit 208 passes the route evaluation result via the transmission unit 209. Send a report.

(Step S513)
The base station device 2 and the relay station device 3-1 start the connection procedure by calling or receiving each other because the evaluation value calculation unit 203 has selected the route R2 as the route having the smallest evaluation value.

(Step S514)
The base station device 2 transmits a communication path change request to the mobile station device 4 via the connection change unit 206. The mobile station apparatus 4 outputs the communication path change request received from the mobile station apparatus 1 to the path change unit 405.

(Step S515)
The mobile station device 4 receives a call or a call between the mobile station device 4 and the relay station device 3-1 based on the communication route change request input to the route change unit 405, thereby connecting the connection procedure. To start. As a method for changing the communication path at this time, soft handover, hard handover, or the like can be used.

(Step S516)
In the mobile station device 4, when the route change is completed, the route change unit 405 transmits a route change completion notification to the relay station device 3-1. The relay station device 3-1 outputs the received route change completion notification to the relay operation management unit 304.

(Step S517)
The relay station device 3-1 receives the route change completion notification from the mobile station device 4. The relay operation management unit 304 transmits a communication path change completion notification to the base station apparatus 2.

(Step S518)
The base station apparatus 2 disconnects communication with the mobile station apparatus 4 through the path R1 based on the input communication path change completion notification.

(Step S519)
The base station device 2 starts communication with the mobile station device 4 through the route R2 based on the input communication route change completion notification.

FIG. 7 is a sequence diagram showing an example of processing when an RLF occurs in communication between the base station device 2 and the relay station device 3-1 according to the embodiment of the present invention. Here, processing is shown when RLF is generated between the base station device 2 and the relay station device 3-1 when communication is performed using the route R2, and the route R1 is changed.

(Step S601)
The mobile station device 4 outputs the reference signal received from the relay station device 3-1 via the transmission path P3 to the SNR measurement unit 403. The SNR measurement unit 403 periodically transmits the transmission channel quality value of the downlink transmission channel P3 calculated based on the SNR of the reference signal to the relay station device 3-1. The mobile station device 4 outputs the reference signal received from the relay station device 3-2 via the transmission path P5 to the SNR measurement unit 403. The SNR measurement unit 403 periodically transmits the transmission channel quality value of the downlink transmission channel P5 calculated based on the SNR of the reference signal to the relay station device 3-1. The mobile station apparatus 4 outputs the reference signal received from the base station apparatus 2 via the transmission path P1 to the SNR measurement unit 403. The SNR measurement unit 403 periodically transmits the transmission channel quality value of the downlink transmission channel P1 calculated based on the SNR of the reference signal to the relay station device 3-1.

(Step S602)
The relay station apparatus 3-1 periodically transmits the transmission path quality values of the downlink transmission paths P1, P3, and P5 received from the mobile station apparatus 4 to the base station apparatus 2.
The relay station apparatus 3-1 outputs the reference signal received from the base station apparatus 2 via the transmission path P2 to the SNR measurement unit 403. The SNR measurement unit 403 periodically transmits the transmission path quality value of the downlink transmission path P2 calculated based on the SNR of the reference signal to the base station apparatus 2.
The relay station device 3-2 outputs the reference signal received from the base station device 2 via the transmission path P4 to the SNR measurement unit 403. The SNR measurement unit 403 periodically transmits the transmission channel quality value of the downlink transmission channel P4 calculated based on the SNR of the reference signal to the base station apparatus 2.

(Step S603)
The base station apparatus 2 receives the transmission path quality value of each transmission path transmitted from the relay station apparatuses 3-1 and 3-2 and the mobile station apparatus 4, and outputs it to the transmission path quality reception unit 202.
The transmission path quality reception unit 202 outputs the transmission path quality value of each transmission path to the evaluation value calculation unit 203.
The evaluation value calculation unit 203 is based on each transmission path quality value input from the transmission path quality reception unit 202, and is an E _{path R1} , E _{path R2} , which is an evaluation value (path evaluation value) of the paths R1, R2, R3, E _{route R3} is calculated. The evaluation value calculation unit 203 outputs route evaluation value information to the route selection unit 204.
The route selection unit 204 determines that the route having the first smallest evaluation value is the route via the relay station device 3-1 from the route evaluation value information input from the evaluation value calculation unit 203. Selected route information including a route ID corresponding to a route having a small evaluation value and a second smallest evaluation value is generated. The route selection unit 204 outputs the selected route information to the connection change unit 206 and the quality evaluation transmission unit 208.

(Step S604)
The base station apparatus 2 transmits the path evaluation value calculated by the evaluation value calculation unit 203 in step S603 to the relay station apparatuses 3-1 and 3-2 (path evaluation result report). At this time, not only the path with the smallest evaluation value, but also a path that is a candidate for an RLF recovery path when the RLF occurs between the base station apparatus 2 and the relay station apparatuses 3-1 and 3-2 (the second path) High quality route).

(Step S605)
The relay station device 3-1 performs a route evaluation result report for transmitting the evaluation value received from the base station device 2 and the route evaluation value to the mobile station device 4. At this time, not only the path having the smallest evaluation value but also a path that becomes a candidate for RLF recovery when an RLF occurs between the base station apparatus 2 and the relay station apparatus 3-1 is transmitted.

(Step S606)
Here, a case where RLF occurs in the transmission path P2 between the base station apparatus 2 and the relay station apparatus 3-1 will be described.

(Step S607)
When the communication disconnection determination unit 309 of the relay station apparatus 3-1 detects the communication disconnection with the base station apparatus 2 based on the input from the reception unit 301, the command to transmit the RLF generation notification to the communication disconnection generation notification unit 310 To do. The communication disconnection occurrence notification unit 310 transmits an RLF occurrence notification to the mobile station apparatus 4.

(Step S608)
The mobile station device 4 receives the RLF occurrence notification from the relay station device 3-1. The mobile station apparatus 4 changes the communication path based on information on a path stored in the storage unit 404 and a candidate for RLF recovery. Here, in the path evaluation result report, since the path that is a candidate for RLF recovery is notified as the path R1, connection from the mobile station apparatus 4 to the base station apparatus 2 is started. As a method for changing the communication path here, soft handover or hard handover can be used.

(Step S609)
The mobile station device 4 transmits a handover request message to the base station device 2.

(Step S610)
The base station apparatus 2 receives the handover request message from the mobile station apparatus 4 and transmits a handover completion message to the mobile station apparatus 4.

(Step S611)
The base station device 2 and the mobile station device 4 complete the handover procedure, and resume radio communication between the base station device 2 and the mobile station device 4 via the route R1.

Thus, in this embodiment, the base station apparatus, the mobile station apparatus, one or more relay station apparatuses that relay data transmission between the base station apparatus and the mobile station apparatus, and the control apparatus that controls the system Is provided. And a plurality of paths that use a transmission path between the base station apparatus and the mobile station apparatus, a transmission path between the base station apparatus and the relay station apparatus, and a transmission path between the relay station apparatus and the mobile station apparatus. There is a route. In a wireless communication system in which any of these routes can be used, the control device calculates evaluation values of a plurality of routes, selects the first highest quality route from the plurality of routes, and other routes Then, the second highest quality route is selected. As a result, when communication cannot be performed via the first highest quality route, communication is possible using the second highest quality route, and communication can be resumed immediately when a communication failure occurs. it can.

(Modification)
Below, the modification of one Embodiment of this invention is demonstrated, referring a sequence diagram. FIG. 8 is a sequence diagram showing an example of processing when RLF occurs in communication between the base station device 2 and the relay station device 3-1 according to the embodiment of the present invention. Here, processing is shown when RLF is generated between the base station device 2 and the relay station device 3-1 when communication is performed using the route R2, and the route R1 is changed.
Since the processing from step S701 to step S705 is the same as the processing from step S601 to step S605 in FIG. 7, the description of these processing is omitted. Further, the processing of step S708 to step S710 is the same as the processing of step S609 to step S611 in FIG. 7, so description of those processing will be omitted.

(Step S706)
The relay station device 3-1 transmits a communication path change notification to the mobile station device 4. The communication path to be notified here is determined from a path evaluation result report periodically received from the base station apparatus 2. Note that the communication path change notification is a communication channel such as a data channel or a control channel, and may be transmitted using a communication channel between the relay station device 3-1 and the mobile station device 4.

(Step S707)
The mobile station device 4 receives the communication path change notification from the relay station device 3-1. The mobile station device 4 changes the communication path based on the communication path change notification. Here, since the RLF recovery communication path is notified as the path R1 in the communication path change notification, the connection from the mobile station apparatus 4 to the base station apparatus 2 is started. As a method for changing the communication path here, soft handover or hard handover can be used.

As described above, according to the present modification, even when information on the communication path is not transmitted to the mobile station apparatus 4 in advance, the mobile station is based on the information of the path evaluation result report held by the relay station apparatus after the occurrence of RLF. The apparatus 4 is notified of the RLF recovery communication path. Thereby, the mobile station apparatus can restart a new communication immediately.

As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to that described above, and various design changes and the like can be made without departing from the scope of the present invention. It is possible to

The present invention relates to a wireless communication path selection method for performing communication between a base station apparatus and a mobile station apparatus even when a communication failure occurs between the base station apparatus and the relay station apparatus in mobile communication, and wireless communication It can be applied to systems and control devices.

2 ... base station device, 2-1 ... control device, 201 ... receiving unit, 202 ... transmission path quality receiving unit, 203 ... evaluation value calculating unit, 204 ... route selecting unit , 205... Reference signal generation unit, 206... Connection change unit, 207... Relay operation instruction unit, 208... Quality evaluation transmission unit, 209.・ ・ ・ Route quality request receiving unit, 212 ... Control unit, 213 ... Storage unit, 3-1 to 3-2 ... Relay station device, 301 ... Receiving unit, 302 ... Reference signal Power measurement unit, 303 ... SNR measurement unit, 304 ... relay operation management unit, 305 ... reference signal generation unit, 306 ... location registration information generation unit, 307 ... path quality transmission unit, 308 ... Transmission path quality transmitter, 309 ... sparse Disconnection determination unit, 310 ... communication disconnection occurrence notification unit, 311 ... transmission unit, 312 ... antenna, 313 ... path quality request unit, 314 ... control unit, 315 ... storage unit, 4 ... mobile station apparatus, 401 ... receiving unit, 402 ... reference signal power measuring unit, 403 ... SNR measuring unit, 404 ... storage unit, 405 ... path changing unit, 406 ..Transmission path quality transmission unit, 407 ... position registration information generation unit, 408 ... transmission unit, 409 ... antenna, 410 ... route quality request unit, 411 ... control unit

Claims (10)

1. A wireless communication path selection method in a control device that controls communication between a base station device, a mobile station device, and a relay station device that relays communication between the base station device and the mobile station device,
   A first transmission path for performing communication between the base station apparatus and the mobile station apparatus without passing through the relay station apparatus, and communication from the base station apparatus to the mobile station apparatus via the relay station apparatus Calculate an evaluation value related to the communication quality of the second transmission path,
   Based on the evaluation value, a first candidate is selected from the first and second transmission paths,
   A wireless communication path selection method for selecting a second candidate other than the first candidate from the first and second transmission paths based on the evaluation value.
2. When the first candidate transmission path is a transmission path via the relay station device, the second candidate is selected from the first and second transmission paths based on the evaluation value The wireless communication path selection method according to claim 1.
3. A wireless communication system comprising a base station device, a mobile station device, a relay station device that relays communication between the base station device and the mobile station device, and a control device that controls the system,
   The controller is
   A first transmission path for performing communication between the base station apparatus and the mobile station apparatus without passing through the relay station apparatus; and a first transmission path for performing communication from the base station apparatus to the mobile station apparatus through the relay station apparatus. A calculation unit for calculating an evaluation value related to communication quality of the two transmission paths;
   Based on the evaluation value, a first candidate is selected from the first and second transmission paths,
   A radio communication system comprising: a selection unit that selects a second candidate other than the first candidate from the first and second transmission paths based on the evaluation value.
4. When the first candidate transmission path is a transmission path via the relay station device, the selection unit selects the second candidate from a communicable transmission path other than the first candidate transmission path. The wireless communication system according to claim 3, wherein the wireless communication system is selected.
5. The wireless communication system according to claim 3, wherein the control device is included in the base station device.
6. The wireless communication system according to claim 3, wherein the control device includes a notification unit that notifies the relay station device of the second candidate.
7. The wireless communication system according to claim 3, wherein the control device includes a notification unit that notifies the mobile station device of the second candidate.
8. 4. The radio according to claim 3, wherein the control device includes a notification unit configured to notify the relay station device of the second candidate when the relay station device is requested to notify the second candidate. Communications system.
9. The said control apparatus is a radio | wireless of Claim 3 provided with the notification part which notifies the said 2nd candidate to the said mobile station apparatus, when notifying the said 2nd candidate from the said mobile station apparatus is requested | required. Communications system.
10. A base station device, a mobile station device, a relay station device that relays communication between the base station device and the mobile station device, and a control device that controls the system,
    A first transmission path for performing communication between the base station apparatus and the mobile station apparatus without passing through the relay station apparatus; and a first transmission path for performing communication from the base station apparatus to the mobile station apparatus through the relay station apparatus. A calculation unit for calculating an evaluation value related to communication quality of the two transmission paths;
    Based on the evaluation value, a first candidate is selected from the first and second transmission paths,
    A selection unit that selects a second candidate other than the first candidate from the first and second transmission paths based on the evaluation value;
    A control device comprising:

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