Power control in a wireless communication system
In a wireless communications system, a serving base station performs outer and closed power control for an overhead channel and a traffic channel for data, either of which can carry an acknowledgement (Ack) channel and Channel Quality Indicator (CQI) channel on an uplink from User Equipment (UE). In an exemplary aspect, data packet communication is implemented in 3GPP LTE Rel. 8 wherein the uplink has a Single Carrier Frequency Division Multiplex (SC-FDM) uplink waveform. The UE performs open loop power control by a determining transmit power spectral density value by using received energy per symbol for a reference signal.
1. A method for transmitting on an uplink in a wireless communication system, comprising:
receiving a reference signal on a downlink;
determining a transmit power spectral density value by using received energy per symbol for the reference signal;
performing open loop power control for an uplink of an overhead channel and a traffic channel based upon the transmit power spectral density value; and
transmitting channel quality feedback that is subject to the transmit power spectral density value determined by open loop power control on either the overhead channel or the traffic channel.
2. The method of claim 1 , further comprising performing open loop power control based upon an open loop adjust value determined to be equal to an uplink receive power spectral density (RxPSD, ul ) value for a user equipment plus a downlink transmit power spectral density (TxPSD DL ) value for a serving node plus a noise figure (NF NodeB ) at the serving node plus a noise over ((NoW) NodeB ) figure at the serving node minus an uplink interference-over-thermal noise (IoT) value at the serving node.
3. The method of claim 1 , further comprising:
receiving a command from a node to adjust a transmit power of a selected one of the overhead channel or the traffic channel that carries the channel quality feedback in accordance with performing outer loop power control, wherein the node determines a detection confidence value for the channel quality feedback and performs outer loop power control for the determined one of the overhead channel or the traffic channel to maintain the detection confidence value at a target; and
transmitting the channel quality feedback on the selected one of the overhead channel or the traffic channel that is subject in part to the transmit power spectral density value determined by open loop power control.
4. A computer program product for transmitting on an uplink in a wireless communication system, the computer program product comprising:
at least one non-transitory computer readable storage medium storing computer executable instructions comprising:
a first set of codes for receiving a reference signal on a downlink;
a second set of codes for determining a transmit power spectral density value by using received energy per symbol for the reference signal;
a third set of codes for performing open loop power control for an uplink of an overhead channel and a traffic channel based upon the transmit power spectral density value; and
a fourth set of codes for transmitting channel quality feedback that is subject to the transmit power spectral density value determined by open loop power control on either the overhead channel or the traffic channel.
5. An apparatus for transmitting on an uplink in a wireless communication system, the apparatus comprising:
means for receiving a reference signal on a downlink;
means for determining a transmit power spectral density value by using received energy per symbol for the reference signal;
means for performing open loop power control for an uplink of an overhead channel and a traffic channel based upon the transmit power spectral density value; and
means for transmitting channel quality feedback that is subject to the transmit power spectral density value determined by open loop power control on either the overhead channel or the traffic channel.
6. An apparatus for transmitting on an uplink in a wireless communication system, the apparatus comprising:
a receiver for receiving a reference signal on a downlink;
a computing platform for determining a transmit power spectral density value by using received energy per symbol for the reference signal and for performing open loop power control for an uplink of an overhead channel and a traffic channel based upon the transmit power spectral density value; and
a transmitter for transmitting channel quality feedback that is subject to the transmit power spectral density value determined by open loop power control on either the overhead channel or the traffic channel.
7. The apparatus of claim 6 , wherein the computing platform is further for performing open loop power control based upon an open loop adjust value determined to be equal to an uplink receive power spectral density (RxPSD ul ) value for a user equipment plus a downlink transmit power spectral density (TxPSD DL ) value for a serving node plus a noise figure (NF NodeB ) at the serving node plus a noise over ((NOW) NodeB ) figure at the serving node minus an uplink interference-over-thermal noise (IoT) value at the serving node.
8. The apparatus of claim 6 , wherein the receiver is further for receiving a command from a node to adjust a transmit power of a selected one of the overhead channel or the traffic channel that carries the channel quality feedback in accordance with an outer loop power control, wherein the node determines a detection confidence value for the channel quality feedback and performs outer loop power control for the determined one of the overhead channel or the traffic channel to maintain the detection confidence value at a target; and
the transmitter is further for transmitting the channel quality feedback on the selected one of the overhead channel or the traffic channel that is subject in part to the transmit power spectral density value determined by open loop power control.