Method and apparatus for long term evolution operation in unlicensed and shared spectrum for cloud radio access networks
There is provided a system, method, and interfaces for Radio Access Networks and Cloud Radio Access Networks.
1. A method comprising:
transmitting, from a lower layer a Baseband Unit (BBU) to a layer of a Remote Radio Unit (RRU), via a fronthaul interface, a discovery reference signal (DRS) transmission; wherein a Control Unit (CU) of the BBU is configured to:
send the DRS signal at a time DRS th,1 (DRS Threshold 1 ) or a time DRS th,2 (DRS Threshold 2 );
send an LBT DRS request at a target subframe for Listen Before Talk (LBT) sensing; and
determine if a discovery measurement timing configuration (DMTC) offset time has passed, and
if so, end the DRS transmission; and if not,
determine if a current time is DRS th,1 or DRS th,2 , (T now =DRS th,1 or T now =DRS th,2 ?); and
if so, send the DRS transmission.
2. The method of claim 1 , wherein the CU is further configured to: if the CU determines the current time is not the time DRS th,1 or the time DRS th,2 (T now =DRS th,1 or T now =DRS th,2 ?) determine if the RRU has received an LBT DRS request; and if not, determine if the DMTC offset time has passed and continue the DRS transmission; if the CU determines the RRU has received the LBT DRS request, determine if the outcome is successful, and if so, end the DRS transmission; if the CU determines the LBD DRS request was not successful, determine if the DMTC offset time has passed and continue the DRS transmission process.
3. A method comprising:
transmitting, from a lower layer a Baseband Unit (BBU) to a layer of a Remote Radio Unit (RRU), via a fronthaul interface, a discovery reference signal (DRS) transmission;
wherein a Control Unit (CU) of the BBU is configured to:
send the DRS signal at a time DRS th,1 or a time DRS th,2 ;
send an LBT DRS request at a target subframe for Listen Before Talk (LBT) sensing; and
determine if a discovery measurement timing configuration (DMTC) offset time has passed; and
wherein the RRU is configured to:
determine if the DRS is received, and if so, buffer the DRS;
if the DRS is not received, continue to listen for the DRS;
if the DRS is buffered, determine if the RRU has received an LBT DRS request from the CU; and
if so, determine if the discovery measurement time window (DMTC) offset time has passed, and if so, terminate the process.
4. The method of claim 3 , wherein the RRU is configured to:
if the DMTC offset time has not passed, determine if a new DRS has been received;
if not, start an LBT spectrum sensing at a configured time;
if a new DRS has been received, drop the existing buffered DRS and buffer a new DRS; and
start the LBT spectrum sensing at the configured time.
5. The method of claim 4 , wherein the RRU is configured to:
determine if the LBT spectrum sensing is successful;
if not, send an LBT DRS failure response to the CU;
determine if the DMTC offset time has passed;
if so, send an LBT DRS success response to the CU, and send the DRS over the air to the target device.
6. A system comprising:
a Baseband Unit (BBU) comprising a Control Unit (CU) configured to transmit, via a fronthaul interface, a discovery reference signal (DRS) transmission to a Remote Radio Unit (RRU), wherein a Control Unit (CU) of the BBU is configured to:
send the DRS signal at a time DRS th,1 or a time DRS th,2 ;
send an LBT DRS request at a target subframe for Listen Before Talk (LBT) sensing; and
determine if a discovery measurement timing configuration (DMTC) offset time has passed; and
if so, end the DRS transmission and if not,
determine if a current time is DRS th,1 or DRS th,2 , (T now =DRS th,1 or T now =DRS th,2 ?); and if so, send the DRS transmission.
7. The system of claim 6 wherein the CU is further configured to:
if the CU determines the current time is not the time DRS th,1 or DRS th,2 (T now =DRS th,1 or T now =DRS th,2 ?), determine if the RRU has received an LBT DRS request and if so, end the DRS transmission; and if not, determine if the DMTC offset time has passed and continue the DRS transmission; if the CU determines the RRU has received the LBT DRS request, determine if the outcome is successful, and if so, end the DRS transmission; if the CU determines the LBD DRS request was not successful, determine if the DMTC offset time has passed and continue the DRS transmission process.
8. A system comprising:
a Baseband Unit (BBU) comprising a Control Unit (CU) configured to transmit, via a fronthaul interface, a discovery reference signal (DRS) transmission to a Remote Radio Unit (RRU), wherein a Control Unit (CU) of the BBU is configured to:
send the DRS signal at a time DRS th,1 or a time DRS th,2 ;
send an LBT DRS request at a target subframe for Listen Before Talk (LBT) sensing; and
determine if a discovery measurement timing configuration (DMTC) offset time has passed; and
wherein the RRU is configured to:
determine if the DRS is received, and if so, buffer the DRS;
if the DRS is not received, continue to listen for the DRS;
if the DRS is buffered, determine if the RRU has received an LBT DRS request from the CU; and
if so, determine if the discovery measurement time window (DMTC) offset time has passed, and if so, terminate the process.
9. The system of claim 8 , wherein the RRU is configured to:
if the DMTC offset time has not passed, determine if a new DRS has been received;
if not, start an LBT spectrum sensing at a configured time;
if a new DRS has been received, drop the existing buffered DRS and buffer a new DRS; and
start the LBT spectrum sensing at the configured time.
10. The system of claim 9 , wherein the RRU is configured to:
determine if the LBT spectrum sensing is successful;
if not, send an LBT DRS failure response to the CU;
determine if the DMTC offset time has passed;
if so, send an LBT DRS success response to the CU, and
send the DRS over the air to the target device.