Providing channel state information about a radio channel
View Patent ↗The invention relates to a method for providing channel state information, CSI, about a radio channel ( 4 ) established between a first network element ( 2 ) and a second network element ( 3 ), the method comprising: providing an estimate (h n ) of a channel coefficient (h n,a ) of the radio channel ( 4 ) based on at least one signal, in particular a pilot signal ( 7 ), transmitted over the radio channel ( 4 ) from the first network element ( 2 ) to the second network element ( 3 ), making a prediction (I) of the channel coefficient (h n,a ) of the radio channel ( 4 ) based on previous estimates (h n,k ), and feeding back information about an error (e n ) between the prediction (I) and the estimate (h n ) of the channel coefficient (h n,a ) from the second network element ( 3 ) to the first network element ( 2 ). The invention also relates to network elements ( 2, 3 ) for implementing the method, as well as to a wireless communication network ( 1 ) comprising the same.
1. A method for providing channel state information about a radio channel established between a first network element and a second network element, the method comprising:
providing an estimate of a channel coefficient of the radio channel for a time step n based on at least one signal, in particular a pilot signal, transmitted over the radio channel from the first network element to the second network element,
making a prediction of the channel coefficient of the radio channel for the same time step n based on previous estimates;
feeding back information about an error between the prediction and the estimate of the channel coefficient from the second network element to the first network element,
wherein the prediction of the channel coefficient is based on a time series of previous estimates combined with prediction coefficients, in particular with linear prediction coefficients; and
updating the prediction coefficients, and providing feedback information about the updated prediction coefficients from the second network element to the first network element, the information about the updated prediction coefficients being fed back less frequently than the information about the error between the prediction and the estimate.
2. The method according to claim 1 , wherein the radio channel is one of a plurality of MIMO channels between the first network element and the second network element, and wherein only a single set of updated prediction coefficients is fed back for all MIMO channels.
3. The method according to claim 1 , wherein the radio channel is a multipath channel and wherein only a single set of updated prediction coefficients is fed back for the multipath channel.
4. The method according to claim 1 , further comprising: multiplexing and encoding the information about the error and the information about the updated prediction coefficients, and providing both types of feedback from the second network element to the first network element using the same feedback channel.
5. The method according to claim 1 , further comprising:
in the first network element, estimating the channel coefficient by making a prediction of the channel coefficient, and correcting the prediction using the feedback information about the error between the prediction and the estimate.
6. A network element, in particular mobile terminal, configured to provide channel state information about a radio channel, comprising at least one processor configured to:
provide an estimate of a channel coefficient of the radio channel for a time step n based on at least one signal, in particular a pilot signal, received from a further network element over the radio channel;
make a prediction of the channel coefficient of the radio channel for the same time step n based on previous estimates; and
provide feedback information about an error between the prediction and the estimate of the channel coefficient to the further network element,
wherein
the at least one processor is configured to make the prediction of the channel coefficient based on a time series of previous estimates combined with prediction coefficients, in particular with linear prediction coefficients;
update the prediction coefficients; and
provide feedback information about the updated prediction coefficients from the network element to the further network element, the information about the updated prediction coefficients being fed back less frequently than the information about the error between the prediction and the estimate.
7. The network element according to claim 6 , wherein the radio channel is one of a plurality of MIMO channels between the network element and the further network element, and wherein the at least one processor is adapted to feed back only a single set of updated prediction coefficients for all MIMO channels.
8. The network element according to claim 6 , wherein the radio channel is a multipath channel and wherein the at least one processor is adapted to feed back only a single set of updated prediction coefficients for the multipath channel.
9. The network element according to claim 6 , wherein the at least one processor is further adapted to multiplex and encode the information about the error and the information about the updated prediction coefficients, and to provide both types of feedback from the network element to the further network element using the same feedback channel.
10. A network element, in particular base station, configured to estimate a channel coefficient of a radio channel for a time step n, the network element comprising at least one processor configured to:
receive information about an error between a prediction and an estimate of the channel coefficient of the radio channel at the time step n from a further network element, the prediction of the channel coefficient being based on a time series of previous estimates combined with prediction coefficients, in particular with linear prediction coefficients;
receive feedback information about updated prediction coefficients from the the further network element, the information about the updated prediction coefficients being received less frequently than the information about the error between the prediction and the estimate;
estimate the channel coefficient by making a prediction of the channel coefficient based on previous estimates; and
correct the prediction using the feedback information about the error between the prediction and the estimate.
11. A wireless communication network, comprising:
at least one network element according to claim 10 ; and,
at least one network element comprising at least one processor configured to—
provide an estimate of a channel coefficient of the radio channel for a time step n based on at least one signal, in particular a pilot signal, received from a further network element over the radio channel,
make a prediction of the channel coefficient of the radio channel for the same time step n based on previous estimates, and
provide feedback information about an error between the prediction and the estimate of the channel coefficient to the further network element, wherein the processing means are adapted to make the prediction of the channel coefficient based on a time series of previous estimates combined with prediction coefficients, in particular with linear prediction coefficients
update the prediction coefficients; and
provide feedback information about the updated prediction coefficients from the network element to the further network element, the information about the updated prediction coefficients being fed back less frequently than the information about the error between the prediction and the estimate.