Method and network node for link adaptation in a wireless communications network
A method in network node for selecting a downlink modulation and coding scheme is provided. The network node obtains information comprising a first uplink signal strength of a transmission from the terminal in the first cell. The network node further obtains information comprising a second uplink signal strength of a transmission from the terminal in the second cell. The network node also obtains scheduled downlink transmission information for the respective first cell and second cell. The network node then selects a downlink modulation and coding scheme for transmission from one or more of the access point serving the first cell and the access point serving the second cell to the terminal. The selection is based on the obtained information comprising the first uplink signal strength, the obtained information comprising the second uplink signal strength, and the obtained scheduled downlink transmission information for the respective first cell and second cell.
1. A method in a network node for selecting a downlink modulation and coding scheme in a wireless communication network, which wireless communication network comprises the network node, a first cell, a second cell and a terminal, the method comprising:
obtaining information comprising a first uplink signal strength of a transmission from the terminal in the first cell, which first uplink signal strength of the transmission from the terminal is measured by an access node serving the first cell;
obtaining information comprising a second uplink signal strength of a transmission from the terminal in the second cell, which second uplink signal strength of the transmission from the terminal is measured by an access node serving the second cell;
obtaining scheduled downlink transmission information for the respective first cell and second cell; and
selecting a downlink modulation and coding scheme for transmission from one or more of the access point serving the first cell and the access point serving the second cell to the terminal, based on the obtained information comprising the first uplink signal strength, the obtained information comprising the second uplink signal strength, and the obtained scheduled downlink transmission information for the respective first cell and second cell.
2. The method according to claim 1 , wherein the selecting further comprises selecting one or more of: a rank, a power, a precoding matrix indicator and a frequency allocation.
3. The method according to claim 1 , wherein the network node is represented by the access node serving the first cell, and wherein information about the first uplink signal strength of the transmission from the terminal is obtained by being measured by the access node serving the first cell.
4. The method according to claim 1 , wherein the scheduled downlink transmission information comprises one or more of: a frequency allocation, a power, a rank, and a precoder, for the respective first cell and second cell.
5. The method according to claim 1 , wherein the respective first uplink signal strength and second uplink signal strength are measured on sounding reference signals from the terminal.
6. The method according to claim 1 , further comprising:
estimating Signal to Interference-plus-Noise Ratio, SINR, for the terminal, based on the obtained information comprising the first uplink signal strength, the obtained information comprising the respective second uplink signal strength, and the obtained scheduled downlink transmission information for the respective access node serving the first cell and access node serving second cell, and
wherein selecting the modulation and coding scheme and, if applicable, any one of the rank, the power, the precoding matrix indicator and the frequency allocation, further is based on the estimated SINR for the terminal.
7. The method according to claim 1 , further comprising:
obtaining from the terminal, one or more downlink Channel State Information, CSI, measurements, and
wherein the selecting the modulation and coding scheme and, if applicable, any one of the rank, the power, the precoding matrix indicator and the frequency allocation, further is based on the respective obtained one or more downlink CSI measurements.
8. A network node for selecting a downlink modulation and coding scheme in a wireless communication network, which wireless communication network is adapted to comprise the network node, a first cell, a second cell and a terminal,
the network node comprising an obtaining circuit configured to obtain information comprising a first uplink signal strength of a transmission from the terminal in a first cell, which first uplink signal strength of the transmission from the terminal is measured by an access node serving the first cell,
which obtaining circuit further is configured to obtain information comprising a second uplink signal strength of a transmission from the terminal in a second cell, which second uplink signal strength of the transmission from the terminal is measured by an access node serving the second cell,
which obtaining circuit further is configured to obtain scheduled downlink transmission information for the respective first cell and second cell, and
the network node further comprising a selecting circuit configured to select a downlink modulation and coding scheme for transmission from one or more of the access point serving the first cell and the access point serving the second cell to the terminal, based on the obtained information comprising the first uplink signal strength, the obtained information comprising the second uplink signal strength, and the obtained scheduled downlink transmission information for the respective first cell and second cell.
9. The network node according to claim 8 , wherein the selecting circuit further is configured to select one or more of: a rank, a power, a precoding matrix indicator and a frequency allocation.
10. The network node according to claim 8 , wherein the network node is represented by the access node serving the first cell, and wherein the information about the first uplink signal strength of the transmission from the terminal is to be obtained by being measured by the access node serving the first cell.
11. The network node according to claim 8 , wherein the scheduled downlink transmission information comprises one or more of: a frequency allocation, a power, a rank, and a precoder, for the respective first cell and second cell.
12. The network node according to claim 8 , wherein the respective first uplink signal strength and second uplink signal strength are to be measured on sounding reference signals from the terminal.
13. The network node according to claim 8 , further comprising:
an estimating circuit configured to estimate a Signal to Interference-plus-Noise Ratio, SINR, for the terminal, based on the obtained information comprising the first uplink signal strength, the obtained information comprising the respective second uplink signal strength, and the obtained scheduled downlink transmission information for the respective access node serving the first cell and access node serving second cell, and
wherein the selecting circuit further is configured to perform the selection of the modulation and coding scheme and, if applicable, any one of the rank, the power, the precoding matrix indicator and the frequency allocation, further based on the estimated SINR for the terminal.
14. The network node according to claim 8 , wherein the obtaining circuit further is configured to obtain from the terminal, one or more downlink Channel State Information, CSI, measurements, and
wherein the selecting circuit further is configured to perform the selection of the modulation and coding scheme and, if applicable, any one of the rank, the power, the precoding matrix indicator and the frequency allocation, further is based on the respective obtained one or more downlink CSI measurements.