System and method for TDD configuration for D2D open discovery
Embodiments are provided to support device-to-device (D2D) communications in a time-division duplexing (TDD) communications system, and ensure that D2D discovery signals are transmitted by user devices on an uplink subframe when there is a TDD frame configuration change. In an embodiment, a user device receives form the network a TDD frame configuration selected from a set of available TDD frame configurations according to the TDD configuration. The device further receives a D2D discovery configuration for a discovery time interval. The user device then allocates a transmission resource a D2D discovery signal within the discovery time interval according to the D2D discovery configuration. The user device is also configured to receive from another device a second D2D discovery signal during the discovery time interval in accordance with the TDD configuration and the D2D discovery configuration.
1. A method for facilitating device to device (D2D) discovery, the method comprising:
transmitting, by an evolved node B (eNB), a device to device (D2D) discovery configuration to one or more user equipments (UEs), the D2D discovery configuration associated with a set of periodically occurring time-domain periods, wherein the D2D discovery configuration includes a time division duplexing (TDD) configuration parameter that identifies a TDD uplink downlink (UL/DL) configuration used to determine a sub-frame pool for D2D discovery, a first indicator for identifying an initial D2D discovery subframe, and a second indicator indicating a D2D discovery period, and
wherein discovery subframes in the sub-frame pool for D2D discovery are determined according to j=(O 3 +i·P), wherein O 3 is the first indicator, P is the second indicator, i is an integer value, and j is a subframe index increasing by 1 for each successive subframe.
2. The method of claim 1 , further comprising:
selecting, by the eNB, the TDD configuration parameter from a set of available TDD configurations; and
determining, by the eNB, the D2D discovery configuration according to the TDD configuration parameter.
3. The method of claim 2 , wherein the set of available TDD configurations includes:
a first TDD configuration comprising corresponding subframes 0 and 5 on downlink bandwidth, subframes 1 and 6 defined as special subframes including an uplink bandwidth portion and a downlink bandwidth portion, and subframes 2 , 3 , 4 , 7 , 8 , and 9 on uplink bandwidth;
a second TDD configuration comprising corresponding subframes 0 , 4 , 5 , and 9 on downlink bandwidth, subframes 1 and 6 defined as special subframes, and subframes 2 , 3 , 7 , and 8 on uplink bandwidth;
a third TDD configuration comprising corresponding subframes 0 , 3 , 4 , 5 , 8 and 9 on downlink bandwidth, subframes 1 and 6 defined as special subframes, and subframes 2 , and 7 on uplink bandwidth;
a fourth TDD configuration comprising corresponding subframes 0 , 5 , 6 , 7 , 8 and 9 on downlink bandwidth, subframe 1 defined as a special subframe, and subframes 2 , 3 , and 4 on uplink bandwidth;
a fifth TDD configuration comprising corresponding subframes 0 , 4 , 5 , 6 , 7 , 8 and 9 on downlink bandwidth, subframe 1 defined as a special subframe, and subframes 2 , and 3 on uplink bandwidth;
a sixth TDD configuration comprising corresponding subframes 0 , 3 , 4 , 5 , 6 , 7 , 8 and 9 on downlink bandwidth, subframe 1 defined as a special subframe, and subframe 2 on uplink bandwidth; and
a seventh TDD configuration comprising corresponding subframes 0 , 5 , and 9 on downlink bandwidth, subframes 1 and 6 defined as special subframes, and subframes 2 , 3 , 4 , 7 and 8 on uplink bandwidth.
4. The method of claim 2 , wherein the D2D discovery configuration identifies subframes on uplink bandwidth of the TDD configuration parameter.
5. The method of claim 4 , wherein the D2D discovery configuration identifies a same corresponding uplink bandwidth subframe on each of the set of available TDD configurations.
6. The method of claim 5 , wherein the D2D discovery configuration identifies subframe 2 on each of the set of available TDD configurations.
7. An evolved node B (eNB) for facilitating device to device (D2D) discovery, the eNB comprising:
at least one processor; and
a non-transitory computer-readable storage medium coupled to the at least one processor and storing a program to be executed by the at least one processor, the program including instructions to:
transmit a device to device (D2D) discovery configuration to one or more user equipments (UEs), the D2D discovery configuration associated with a set of periodically occurring time-domain periods, wherein the D2D discovery configuration includes a time division duplexing (TDD) configuration parameter that identifies a TDD uplink downlink (UL/DL) configuration used to determine a sub-frame pool for D2D discovery, a first indicator for identifying an initial D2D discovery subframe, and a second indicator indicating a D2D discovery period, and
wherein discovery subframes in the sub-frame pool for D2D discovery are determined according to j=(O 3 +i·P), wherein O 3 is the first indicator, P is the second indicator, i is an integer value, and j is a subframe index increasing by 1 for each successive subframe.
8. The eNB of claim 7 , wherein the program further includes instructions to:
select the TDD configuration parameter from a set of available TDD configurations; and
determine the D2D discovery configuration according to the TDD configuration parameter.
9. The eNB of claim 8 , wherein the program further includes instructions to:
access the set of available TDD configurations, the set of available TDD configurations including:
a first TDD configuration comprising corresponding subframes 0 and 5 on downlink bandwidth, subframes 1 and 6 defined as special subframes including an uplink bandwidth portion and a downlink bandwidth portion, and subframes 2 , 3 , 4 , 7 , 8 , and 9 on uplink bandwidth;
a second TDD configuration comprising corresponding subframes 0 , 4 , 5 , and 9 on downlink bandwidth, subframes 1 and 6 defined as special subframes, and subframes 2 , 3 , 7 , and 8 on uplink bandwidth;
a third TDD configuration comprising corresponding subframes 0 , 3 , 4 , 5 , 8 and 9 on downlink bandwidth, subframes 1 and 6 defined as special subframes, and subframes 2 , and 7 on uplink bandwidth;
a fourth TDD configuration comprising corresponding subframes 0 , 5 , 6 , 7 , 8 and 9 on downlink bandwidth, subframe 1 defined as a special subframe, and subframes 2 , 3 , and 4 on uplink bandwidth;
a fifth TDD configuration comprising corresponding subframes 0 , 4 , 5 , 6 , 7 , 8 and 9 on downlink bandwidth, subframe 1 defined as a special subframe, and subframes 2 , and 3 on uplink bandwidth;
a sixth TDD configuration comprising corresponding subframes 0 , 3 , 4 , 5 , 6 , 7 , 8 and 9 on downlink bandwidth, subframe 1 defined as a special subframe, and subframe 2 on uplink bandwidth; and
a seventh TDD configuration comprising corresponding subframes 0 , 5 , and 9 on downlink bandwidth, subframes 1 and 6 defined as special subframes, and subframes 2 , 3 , 4 , 7 and 8 on uplink bandwidth.
10. The eNB of claim 8 , wherein the D2D discovery configuration identifies subframes on uplink bandwidth of the TDD configuration parameter.
11. The eNB of claim 10 , wherein the D2D discovery configuration identifies a same corresponding uplink bandwidth subframe on each of the set of available TDD configurations.
12. The eNB of claim 11 , wherein the D2D discovery configuration identifies subframe 2 on each of the set of available TDD configurations.
13. An apparatus for facilitating device to device (D2D) discovery, the apparatus comprising:
a transmitter, the transmitter configured to transmit a device to device (D2D) discovery configuration to one or more user equipments (UEs), the D2D discovery configuration associated with a set of periodically occurring time-domain periods, wherein the D2D discovery configuration includes a time division duplexing (TDD) configuration parameter that identifies a TDD uplink downlink (UL/DL) configuration used to determine a sub-frame pool for D2D discovery, a first indicator for identifying an initial D2D discovery subframe, and a second indicator indicating a D2D discovery period,
wherein discovery subframes in the sub-frame pool for D2D discovery are determined according to j=(O 3 +i·P), wherein O 3 is the first indicator, P is the second indicator, i is an integer value, and j is a subframe index increasing 1 for each successive subframe.
14. The apparatus of claim 13 , further comprising:
a processor operatively coupled to the transmitter, the processor configured to select the TDD configuration parameter from a set of available TDD configurations, the processor further configured to determine the D2D discovery configuration according to the TDD configuration parameter.
15. The apparatus of claim 14 , further comprising:
a memory operatively coupled to the processor, the memory configured to store the set of available TDD configurations, the set of available TDD configurations including:
a first TDD configuration comprising corresponding subframes 0 and 5 on downlink bandwidth, subframes 1 and 6 defined as special subframes including an uplink bandwidth portion and a downlink bandwidth portion, and subframes 2 , 3 , 4 , 7 , 8 , and 9 on uplink bandwidth;
a second TDD configuration comprising corresponding subframes 0 , 4 , 5 , and 9 on downlink bandwidth, subframes 1 and 6 defined as special subframes, and subframes 2 , 3 , 7 , and 8 on uplink bandwidth;
a third TDD configuration comprising corresponding subframes 0 , 3 , 4 , 5 , 8 and 9 on downlink bandwidth, subframes 1 and 6 defined as special subframes, and subframes 2 , and 7 on uplink bandwidth;
a fourth TDD configuration comprising corresponding subframes 0 , 5 , 6 , 7 , 8 and 9 on downlink bandwidth, subframe 1 defined as a special subframe, and subframes 2 , 3 , and 4 on uplink bandwidth;
a fifth TDD configuration comprising corresponding subframes 0 , 4 , 5 , 6 , 7 , 8 and 9 on downlink bandwidth, subframe 1 defined as a special subframe, and subframes 2 , and 3 on uplink bandwidth;
a sixth TDD configuration comprising corresponding subframes 0 , 3 , 4 , 5 , 6 , 7 , 8 and 9 on downlink bandwidth, subframe 1 defined as a special subframe, and subframe 2 on uplink bandwidth; and
a seventh TDD configuration comprising corresponding subframes 0 , 5 , and 9 on downlink bandwidth, subframes 1 and 6 defined as special subframes, and subframes 2 , 3 , 4 , 7 and 8 on uplink bandwidth.
16. The apparatus of claim 14 , wherein the D2D discovery configuration identifies subframes on uplink bandwidth of the TDD configuration parameter.
17. The apparatus of claim 16 , wherein the D2D discovery configuration identifies a same corresponding uplink bandwidth subframe on each of the set of available TDD configurations.
18. The apparatus of claim 17 , wherein the D2D discovery configuration identifies subframe 2 on each of the set of available TDD configurations.