Control apparatus, control method, and wireless communication system

1. A control apparatus in a wireless communication system including a base station, a plurality of relay stations, and a plurality of terminals, each of the plurality of relay stations being configured to relay wireless signals between the base station and the plurality of terminals, the control apparatus comprising:

a memory; and

a processor coupled to the memory and configured to

determine relay schedules based on first information associated with first path losses between any pair of the plurality of relay stations, each of the relay schedules defining each of relay periods for each of the plurality of relay stations relaying the wireless signals, and

transmit each of the relay schedules to each of the plurality of relay stations respectively.

2. The control apparatus according to claim 1 , wherein

the processor is further configured to

identify relay stations from the plurality of relay stations, for which the first path losses respective to the identified relay stations are less than a first value, and

determine the relay schedules for the identified relay stations so that the relay periods respective to the identified relay stations do not overlap each other.

3. The control apparatus according to claim 2 , wherein

the processor is further configured to determine the relay schedules based on second information associated with second path losses between any pair of one of the plurality of relay stations and one of the plurality of terminals.

4. The control apparatus according to claim 3 , wherein

the identified relay stations include a first relay station and a second relay station, and

the processor is further configured to determine a first relay schedule for the first relay station and a second relay schedule for the second relay station so that a first relay period of the first relay schedule is shorter than a second relay period of the second relay schedule when a first number is less than a second number, the first number is a number of terminals for which second path losses with the first relay station are less than a second value, the second number is a number of terminals for which second path losses with the second relay station are less than the second value.

5. The control apparatus according to claim 4 , wherein

the processor is further configured to determine the relay schedules so that the relay periods, for the plurality of relay station for which second path losses are greater than the second value, are set to none of the sequential periods having the given length.

6. The control apparatus according to claim 2 , wherein

each of the relay periods are defined among sequential periods, and each of the sequential periods has a given length.

7. The control apparatus according to claim 6 , wherein

the processor is further configured to determine the relay schedules so that the relay periods, for the plurality of relay station for which first path losses are greater than first value, are set to all of the sequential periods having the given length.

8. The control apparatus according to claim 1 , wherein

the processor is further configured to determine the relay schedules based on second information associated with second path losses between any pair of one of the plurality of relay stations and one of the plurality of terminals.

9. The control apparatus according to claim 1 , wherein

each of the relay periods are defined among sequential periods, and each of the sequential periods has a given length.

10. The control apparatus according to claim 1 , wherein

the processor is further configured to

receive other relay schedules for another plurality of relay stations relaying other wireless signals between another base station and another plurality of terminals,

update the relay schedules based on the received other relay schedules, and

transmit each of the updated relay schedules to each of the plurality of relay stations respectively.

11. The control apparatus according to claim 1 , wherein each period of the sequential periods is substantially equal to a period during which the plurality of terminals is configured to measure the wireless signals.

12. The control apparatus according to claim 1 , wherein the first information is generated based on measurement of the wireless signals at the plurality of relay stations.

13. The control apparatus according to claim 1 , wherein the control apparatus includes the base station.

14. The control apparatus according to claim 1 , wherein the plurality of relay stations are full duplex type.

15. The control apparatus according to claim 1 , wherein the plurality of relay stations have no scheduler for the plurality of terminals.

16. A control method for a wireless communication system including a base station, a plurality of relay stations, and a plurality of terminals, each of the plurality of relay stations being configured to relay wireless signals between the base station and the plurality of terminals, the control method comprising:

determining relay schedules based on first information associated with first path losses between any pair of the plurality of relay stations, each of the relay schedules defining each of relay periods for each of the plurality of relay stations relaying the wireless signals; and

transmitting each of the relay schedules to each of the plurality of relay stations respectively.

17. A wireless communication system comprising:

a base station;

a plurality of terminals;

a plurality of relay stations, each of the plurality of relay stations being configured to relay wireless signals between the base station and the plurality of terminals; and

a control apparatus configured to

determine relay schedules based on first information associated with first path losses between any pair of the plurality of relay stations, each of the relay schedules defining each of relay periods for each of the plurality of relay stations relaying the wireless signals, and

transmit each of the relay schedules to each of the plurality of relay stations respectively.