Uplink transmission timing
Embodiments herein relates to a method in a radio base station ( 12 ) for handling a timing of uplink transmission from a user equipment ( 10 ) to the radio base station ( 12 ) in a radio communications network. The user equipment ( 10 ) is served in a cell ( 14 ) controlled by the radio base station ( 12 ), and which radio base station ( 12 ) and user equipment ( 10 ) are comprised in the radio communications network. The communications in the cell ( 14 ) are organized in radio frames comprising subframes. The radio base station ( 12 ) receives a first uplink transmission from the user equipment ( 10 ) in a subframe related to the radio base station ( 12 ). The radio base station then estimates a time parameter value based on a distance between the user equipment ( 10 ) and the radio base station ( 12 ) when the first uplink transmission is transmitted from the user equipment ( 10 ). The radio base station ( 12 ) then sets a time value (N TA1 ) in a message, which time value (N TA1 ) is to be used to set a timing of a second uplink transmission at the user equipment ( 10 ). The time value (N TA1 ) is based on the estimated time parameter value and a time offset value (ΔT). The radio base station ( 12 ) then transmits the message comprising the time value (N TA1 ) to the user equipment.
1. A method in a radio base station for handling a timing of uplink transmissions from a user equipment to the radio base station in a radio communications network, in which the user equipment is served in a cell controlled by the radio base station, and in which cell communications are organized in radio frames comprising subframes, the method comprising:
receiving a first uplink transmission from the user equipment in a subframe related to the radio base station;
estimating a time parameter value based on a distance between the user equipment and the radio base station when the first uplink transmission is transmitted from the user equipment;
setting a time value in a message, which time value is to be used to set a timing of a second uplink transmission at the user equipment, and which time value is based on the estimated time parameter value and a time offset value for increasing a time budget for processing in the radio base station; and
transmitting the message comprising the time value to the user equipment.
2. The method according to claim 1 , wherein the first uplink transmission comprises a random access preamble in a random access request from the user equipment and the time value is comprised in a random access response.
3. The method according to claim 1 , wherein the distance between the user equipment and the radio base station is based on a position of the received first uplink transmission in a time domain of the subframe related to the radio base station.
4. The method according to claim 1 , wherein the time value is comprised in a time alignment command of the message.
5. The method according to claim 1 , wherein the time offset value is pre-set or based on statistics measured in the cell.
6. The method according to claim 1 , wherein the time offset value is continuously updated based on measurements within the cell.
7. The method according to claim 1 , further comprising reducing a data rate of the user equipment when the distance between the user equipment and the radio base station exceeds a threshold value.
8. The method according to claim 7 , wherein the reducing comprises reducing a transport block size for uplink transmission for the user equipment.
9. A radio base station for handling a timing of uplink transmission from a user equipment to the radio base station in a radio communications network, in which the user equipment is served in a cell controlled by the radio base station, and in which cell communications are organized in radio frames comprising subframes, and wherein the radio base station comprises;
a receiver configured to receive a first uplink transmission from the user equipment in a subframe related to the radio base station;
an estimating circuit configured to estimate a time parameter value based on a distance between the user equipment and the radio base station when the first uplink transmission is transmitted from the user equipment;
a setting circuit configured to set a time value in a message, which time value is to be used to set a timing of a second uplink transmission at the user equipment, and which time value is based on the estimated time parameter value and a time offset value for increasing a time budget for processing in the radio base station; and
a transmitter configured to transmit the message comprising the time value to the user equipment.
10. The radio base station according to claim 9 , wherein the first uplink transmission comprises a random access preamble in a random access request from the user equipment and wherein the time value is comprised in a random access response.
11. The radio base station according to claim 9 , wherein the distance between the user equipment and the radio base station is based on a position of the received first uplink transmission in a time domain of the subframe related to the radio base station.
12. The radio base station according to claim 9 , wherein the time value is comprised in a time alignment command of the message.
13. The radio base station according to claim 9 , wherein the time offset value is pre-set or based on statistics measured in the cell.
14. The radio base station according to claim 9 , wherein the time offset value is continuously updated based on measurements within the cell.
15. The radio base station according to claim 9 , further comprising a reduction circuit configured to reduce a data rate of the user equipment when the distance between the user equipment and the radio base station exceeds a threshold value.
16. The radio base station according to claim 9 , wherein the reducing circuit is configured to reduce a transport block size for uplink transmission for the user equipments.