Relay apparatus and relay method

1. A relay device for relaying communications between a plurality of radio devices that perform radio communications with a terminal and a radio control apparatus that controls the plurality of radio devices, the relay device comprising:

a plurality of signal combiners that are each provided for one of functional splitting points between the plurality of radio devices and the radio control apparatus, and are each configured to convert signal data outputted from a signal switcher based on a signal format in accordance with the one of the functional splitting points, and transmit the converted signal data to the radio control apparatus,

wherein the signal switcher is configured to output the signal data transmitted from the one of the plurality of radio devices, to one of the plurality of signal combiners supporting one of the functional splitting points that corresponds to the one of the plurality of radio devices,

wherein the functional splitting point is a splitting point in a protocol stack including a plurality of layers composed of one or more functions, when functions at and above either layer or function are assigned to the radio control apparatus, and functions below said layer or function are assigned to the radio devices,

wherein one functional splitting point is set in the protocol stack, and

wherein the plurality of signal combiners are provided corresponding to a plurality of protocol stacks in which different functional splitting points are set therein.

2. The relay device according to claim 1 , wherein the converted signal data is first signal data obtained by adding a plurality of pieces of the signal data, second signal data obtained by selecting one of the plurality of pieces of the signal data, or third signal data indicating a signal transmitted from the terminal detected in accordance with the plurality of pieces of the signal data.

3. The relay device according to claim 2 , wherein the second signal data is signal data selected in accordance with control information included in signals transmitted from the plurality of radio devices.

4. The relay device according to claim 2 , wherein the second signal data is signal data selected in accordance with a control signal transmitted and received between the radio devices and the radio control apparatus.

5. A relay device for relaying communications between a plurality of radio devices that perform radio communications with a terminal and a radio control apparatus that controls the plurality of radio devices, the relay device comprising:

a plurality of signal combiners that are each provided for one of functional splitting points between the plurality of radio devices and the radio control apparatus, and are each configured to convert signal data outputted from a signal switcher based on a signal format in accordance with the one of the functional splitting points and transmit the converted signal data to the radio control apparatus;

wherein the signal switcher is configured to output a plurality of pieces of the signal data transmitted from the plurality of radio devices respectively, to the plurality of signal combiners supporting the functional splitting points that correspond to the plurality of radio devices that transmitted the signal data respectively,

wherein the functional splitting point is a splitting point in a protocol stack including a plurality of layers composed of one or more functions, when functions at and above either layer or function are assigned to the radio control apparatus, and functions below said layer or function are assigned to the radio devices,

wherein one functional splitting point is set in the protocol stack, and

wherein the plurality of signal combiners are provided corresponding to a plurality of protocol stacks in which different functional splitting points are set therein.

6. The relay device according to claim 5 , wherein the converted signal data is first signal data obtained by adding the plurality of pieces of the signal data, second signal data obtained by selecting one of the plurality of pieces of the signal data, or third signal data indicating a signal transmitted from the terminal detected in accordance with the plurality of pieces of the signal data.

7. The relay device according to claim 6 , wherein the second signal data is signal data selected in accordance with control information included in signals transmitted from the plurality of radio devices.

8. The relay device according to claim 6 , wherein the second signal data is signal data selected in accordance with a control signal transmitted and received between the radio devices and the radio control apparatus.

9. The relay device according to claim 5 , wherein the relay device further comprises a signal distributer configured to copy signal data transmitted from the radio control apparatus, and transmit the copied signal data to only a target radio device of the plurality of the radio devices in accordance with the functional splitting point.

10. A relay device for relaying communications between a plurality of radio devices that perform radio communications with a terminal and a radio control apparatus that controls the radio devices, the relay device comprising a signal distributer configured to copy signal data transmitted from the radio control apparatus, and transmit the copied signal data to only a target radio device of the plurality of the radio devices in accordance with a functional splitting point,

wherein the functional splitting point is a splitting point in a protocol stack including a plurality of layers composed of one or more functions, when functions at and above either layer or function are assigned to the radio control apparatus, and functions below said layer or function are assigned to the radio devices; and

wherein one functional splitting point is set in the protocol stack.

11. A computer-implemented relay method for relaying communications between a plurality of radio devices that perform radio communications with a terminal and a radio control apparatus that controls the plurality of radio devices, the method comprising:

converting, by a plurality of signal combiners that are each provided for one of functional splitting points between the plurality of radio devices and the radio control apparatus, signal data outputted from a signal switcher based on a signal format in accordance with the one of the functional splitting points;

transmitting, by the plurality of signal combiners, the converted signal data to the radio control apparatus; and

outputting, by the signal switcher, the signal data transmitted from the one of the plurality of radio devices, to one of the plurality of signal combiners supporting one of the functional splitting points that corresponds to the one of the plurality of radio devices,

wherein the functional splitting point is a splitting point in a protocol stack including a plurality of layers composed of one or more functions, when functions at and above either layer or function are assigned to the radio control apparatus, and functions below said layer or function are assigned to the radio devices,

wherein one functional splitting point is set in the protocol stack, and

wherein the plurality of signal combiners are provided corresponding to a plurality of protocol stacks in which different functional splitting points are set therein.

12. A computer-implemented relay method for relaying communications between a plurality of radio devices that perform radio communications with a terminal and a radio control apparatus that controls the plurality of radio devices, the method comprising:

converting, by a plurality of signal combiners that are each provided for one of functional splitting points between the plurality of radio devices and the radio control apparatus, signal data outputted from a signal switcher based on a signal format in accordance with the one of the functional splitting points;

transmitting, by the plurality of signal combiners, the converted signal data to the radio control apparatus; and

outputting, by the signal switcher, a plurality of pieces of the signal data transmitted from the plurality of radio devices respectively, to the plurality of signal combiners supporting the functional splitting points that correspond to the plurality of radio devices that transmitted the signal data respectively,

wherein the functional splitting point is a splitting point in a protocol stack including a plurality of layers composed of one or more functions, when functions at and above either layer or function are assigned to the radio control apparatus, and functions below said layer or function are assigned to the radio devices,

wherein one functional splitting point is set in the protocol stack, and wherein the plurality of signal combiners are provided corresponding to a plurality of protocol stacks in which different functional splitting points are set therein.