Method and Apparatus for Performing D2d Communication

1. A method for performing D2D (Device-to-Device) communication in a communication system, wherein the communication system at least comprises a base station (BS) and a user equipment (UE) in cellular communication with the BS, and wherein the D2D communication is performed between a D2D transmitter and a D2D receiver and interferes with the cellular communication, the method comprising: obtaining modulation and coding scheme (MCS) information on the cellular communication between the BS and the UE; and determining a transmitting power for the D2D communication based on a channel information from the UE to the BS based on the MCS information, a channel information from the D2D transmitter to the BS, and outage probability of the cellular communication in uplink or downlink, so as to reduce the interference from the D2D communication to the cellular communication.

2. The method of claim 1 , wherein the cellular communication is in the uplink, and wherein obtaining the MCS information on the cellular communication between the BS and the UE comprises: obtaining the MCS information transmitted from the BS to the UE, wherein the MCS information is designated by the BS to the UE.

3. The method of claim 1 , wherein the cellular communication is in the downlink, and wherein obtaining the MCS information on the cellular communication between the BS and the UE comprises: obtaining the MCS information transmitted from the BS to the UE, wherein the MCS information is determined by the BS based on CQI measured by the UE in response to receiving reference signals from the BS.

4. The method of claim 1 , wherein determining a transmitting power for the D2D communication based on the MCS information comprises: obtaining a power limit for all of at least one shared subband which is shared by the D2D communication and the cellular communication based on the MCS information; and determining the transmitting power for the D2D communication based on the power limit.

5. The method of claim 4 , wherein the cellular communication is in the uplink, and wherein obtaining a power limit for all of at least one shared subband which is shared by the D2D communication and the cellular communication based on the MCS information comprises: obtaining the channel information from the UE to the BS based on the MCS information; obtaining the channel information from the D2D transmitter to the BS based on path-loss from the D2D transmitter to the BS; and calculating the power limit for all of the at least one shared subband based on the channel information from the UE to the BS, the channel information from the D2D transmitter to the BS, and the outage probability of the uplink.

6. The method of claim 5 , wherein obtaining channel information from the D2D transmitter to the BS based on the path-loss from the D2D transmitter to the BS comprises: calculating a path-loss from the BS to the D2D transmitter based on reference signals sent from the BS; and obtaining the path-loss from the D2D transmitter to the BS based on channel reciprocity and the path-loss from the BS to the D2D transmitter.

7. The method of claim 4 , wherein the cellular communication is in the downlink, and wherein obtaining a power limit for all of at least one shared subband shared by the D2D communication and the cellular communication based on the MCS information comprises: obtaining a channel information from the BS to the UE based on the MCS information; obtaining a channel information from the D2D transmitter to the UE based on path-loss from the D2D transmitter to the UE; and calculating the power limit for all of the at least one shared subband based on the channel information from the BS to the UE, the channel information from the D2D transmitter to the UE, and outage probability of the downlink.

8. The method of claim 7 , wherein obtaining channel information from the D2D transmitter to the UE based on path-loss from the D2D transmitter to the UE comprises: determining the distance between the D2D transmitter and the UE; and calculating the path-loss from the D2D transmitter to the UE based on the distance between the D2D transmitter and the UE.

9. The method of claim 4 , wherein determining the transmitting power for the D2D communication based on the power limit comprises: obtaining a total power limitation at the D2D transmitter; and determining the transmitting power for the D2D communication based on the power limit for all of the at least one shared subband and the total power limitation.

10. The method of claim 9 , wherein determining the transmitting power for the D2D communication based on the power limit for all of the at least one shared subband and the total power limitation comprises: obtaining interference suffered by the D2D receiver; calculating a transmission rate for each of the at least one shared subband based on the obtained interference; and obtaining a subband transmitting power for each of the at least one shared subband by maximizing the sum of the calculated transmission rate, wherein each subband transmitting power does not exceed the power limit for the corresponding subband, and the sum of subband transmitting powers does not exceed the total power limitation.

11. The method of claim 10 , wherein obtaining interference suffered by the D2D receiver comprises: obtaining long term interference to the D2D receiver, wherein the long term interference is estimated based on historical interference at the D2D receiver or set as a predetermined value.

12. The method of claim 10 , wherein obtaining interference suffered by the D2D receiver comprises: obtaining instantaneous interference to the D2D receiver, wherein the instantaneous interference is measured by the D2D receiver for each of the at least one shared subband which is shared by the UE and the D2D transmitter.

13. An apparatus for performing D2D (Device-to-Device) communication in a communication system, wherein the communication system at least comprises a base station (BS) and a user equipment (UE) in cellular communication with the BS, and wherein the D2D communication is performed between a D2D transmitter and a D2D receiver and interferes with the cellular communication, the apparatus comprising: obtaining unit configured to obtain modulation and coding scheme (MCS) information on the cellular communication between the BS and the UE; and determining unit configured to determine a transmitting power for the D2D communication based on the MCS information, so as to reduce the interference from the D2D communication to the cellular communication.

14. The apparatus of claim 13 , wherein the determining unit comprises: obtaining means configured to obtain a power limit for all of at least one shared subband which is shared by the D2D communication and the cellular communication based on the MCS information; and determining means configured to determine the transmitting power for the D2D communication based on the power limit.

15. The apparatus of claim 14 , wherein the determining means comprises: means configured to obtain a total power limitation at the D2D transmitter; and means configured to determine the transmitting power for the D2D communication based on the power limit for all of the at least one shared subband and the total power limitation.

16. The apparatus of claim 15 , wherein the means configured to determine the transmitting power for the D2D communication based on the power limit for all of the at least one shared subband and the total power limitation comprises: means configured to obtain interference suffered by the D2D receiver; means configured to calculate a transmission rate for each of the at least one shared subband based on the obtained interference; and means configured to obtain a subband transmitting power for each of the at least one shared subband by maximizing the sum of the calculated transmission rate, wherein each subband transmitting power does not exceed the power limit for the corresponding subband, and the sum of subband transmitting powers does not exceed the total power limitation.

17. An apparatus for performing D2D (Device-to-Device) communication in a communication system, wherein the communication system at least comprises a base station (BS) and a user equipment (UE) in cellular communication with the BS, and wherein the D2D communication is performed between a D2D transmitter and a D2D receiver and interferes with the cellular communication, the apparatus comprising: at least one non-transitory memory operable to store program code; and at least one processor operable to read said program code and operate as instructed by said program code, said program code comprising: obtaining code that obtains modulation and coding scheme (MCS) information on the cellular communication between the BS and the UE; and determining code that determines a transmitting power for the D2D communication based on a channel information from the UE to the BS based on the MCS information, a channel information from the D2D transmitter to the BS, and outage probability of the cellular communication in uplink or downlink, so as to reduce the interference from the D2D communication to the cellular communication.

18. The apparatus of claim 17 , wherein the cellular communication is in uplink, and wherein the obtaining code further obtains the MCS information transmitted from the BS to the UE, wherein the MCS information is designated by the BS to the UE.

19. The apparatus of claim 17 , wherein the cellular communication is in downlink, and wherein the obtaining code further obtains the MCS information transmitted from the BS to the UE, wherein the MCS information is determined by the BS based on CQI measured by the UE in response to receiving reference signals from the BS.

20. The apparatus of claim 17 , wherein the determining code further obtains a power limit for all of at least one shared subband which is shared by the D2D communication and the cellular communication based on the MCS information; and determines the transmitting power for the D2D communication based on the power limit.

21. The apparatus of claim 20 , wherein the cellular communication is in the uplink, and wherein the obtaining code further: obtains the channel information from the UE to the BS based on the MCS information; obtains the channel information from the D2D transmitter to the BS based on path-loss from the D2D transmitter to the BS; and calculates the power limit for all of the at least one shared subband based on the channel information from the UE to the BS, the channel information from the D2D transmitter to the BS, and outage probability of the uplink.

22. The apparatus of claim 21 , wherein the obtaining code further: calculates path-loss from the BS to the D2D transmitter based on reference signals sent from the BS; and obtains the path-loss from the D2D transmitter to the BS based on channel reciprocity and the path-loss from the BS to the D2D transmitter.

23. The apparatus of claim 20 , wherein the cellular communication is in the downlink, and wherein the obtaining code further: obtains a channel information from the BS to the UE based on the MCS information; obtains a channel information from the D2D transmitter to the UE based on path-loss from the D2D transmitter to the UE; and calculates the power limit for all of the at least one shared subband based on the channel information from the BS to the UE, the channel information from the D2D transmitter to the UE, and outage probability of the downlink.

24. The apparatus of claim 23 , wherein the obtaining code further: determines a distance between the D2D transmitter and the UE; and calculates the path-loss from the D2D transmitter to the UE based on the distance between the D2D transmitter and the UE.

25. The apparatus of claim 20 , wherein the determining code further obtains a total power limitation at the D2D transmitter; and determines the transmitting power for the D2D communication based on the power limit for all of the at least one shared subband and the total power limitation.

26. The apparatus of claim 25 , wherein the determining code further obtains interference suffered by the D2D receiver; calculates a transmission rate for each of the at least one shared subband based on the obtained interference; and obtains a subband transmitting power for each of the at least one shared subband by maximizing the sum of the calculated transmission rate, wherein each subband transmitting power does not exceed the power limit for the corresponding subband, and the sum of subband transmitting powers does not exceed the total power limitation.

27. The apparatus of claim 26 , wherein the determining code further obtains long term interference to the D2D receiver, wherein the long term interference is estimated based on historical interference at the D2D receiver or set as a predetermined value.

28. The apparatus of claim 26 , wherein the determining code further obtains instantaneous interference to the D2D receiver, wherein the instantaneous interference is measured by the D2D receiver for each of at least one shared subband which is shared by the UE and the D2D transmitter.