Method for acquiring channel state information in FDD MIMO wireless networks
First Claim
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1. A method for a BS to acquire DL CSI in a FDD wireless network comprising a second FDD apparatus who normally receives UL signals in frequency band F2 from and sends DL signals in frequency band F1 to a first FDD apparatus whose DL CSI is to be estimated;
- a CSI estimation enable control signal and a set of switches controlled by the CSI estimation enable control signal in the first FDD apparatus; and
upon the CSI estimation enable control signal becoming active, changing the connections of the set of switches so that the transmitting frequency band of a transmitter in the first FDD apparatus is changed from the normal transmitting frequency band F2 to the normal receiving frequency band F1 and the transmitting signal is transmitted out of a normal receiving antenna instead of a normal transmitting antenna; and
correspondingly, a second CSI estimation enable control signal and a second set of switches controlled by the CSI estimation enable control signal in the second FDD apparatus; and
upon the CSI estimation enable control signal becoming active, changing the connections of the set of switches so that the receiving frequency band of a receiver in the second FDD apparatus is changed from the normal receiving frequency band F2 to the normal transmitting frequency band F1 and the receiving signal is received from a normal transmitting antenna instead of a normal receiving antenna.
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Abstract
This invention presents methods and circuits for a BS to acquire DL CSI in a FDD wireless network comprising switching the normal transmitting and receiving frequencies in a first and a second FDD apparatus, and using UL pilot signals to estimate the DL CSI based on reciprocity of the over the air channels.
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Citations
16 Claims
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1. A method for a BS to acquire DL CSI in a FDD wireless network comprising a second FDD apparatus who normally receives UL signals in frequency band F2 from and sends DL signals in frequency band F1 to a first FDD apparatus whose DL CSI is to be estimated;
- a CSI estimation enable control signal and a set of switches controlled by the CSI estimation enable control signal in the first FDD apparatus; and
upon the CSI estimation enable control signal becoming active, changing the connections of the set of switches so that the transmitting frequency band of a transmitter in the first FDD apparatus is changed from the normal transmitting frequency band F2 to the normal receiving frequency band F1 and the transmitting signal is transmitted out of a normal receiving antenna instead of a normal transmitting antenna; and
correspondingly, a second CSI estimation enable control signal and a second set of switches controlled by the CSI estimation enable control signal in the second FDD apparatus; and
upon the CSI estimation enable control signal becoming active, changing the connections of the set of switches so that the receiving frequency band of a receiver in the second FDD apparatus is changed from the normal receiving frequency band F2 to the normal transmitting frequency band F1 and the receiving signal is received from a normal transmitting antenna instead of a normal receiving antenna. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- a CSI estimation enable control signal and a set of switches controlled by the CSI estimation enable control signal in the first FDD apparatus; and
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8. A circuit in a first FDD apparatus for estimating DL CSI in a FDD wireless network comprising generator of a CSI estimation enable control signal and a set of switches controlled by the CSI estimation enable control signal in the first FDD apparatus;
- and upon the CSI estimation enable control signal becoming active, changing the connections of the set of switches so that the transmitting frequency band of a transmitter in the first FDD apparatus is changed from the normal transmitting frequency band F2 to the normal receiving frequency band F1 and the transmitting signal is transmitted out of a normal receiving antenna instead of a normal transmitting antenna.
- View Dependent Claims (9, 10)
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11. A circuit in a second FDD apparatus for estimating DL CSI in a FDD wireless network comprising generator of a CSI estimation enable control signal and a set of switches controlled by the CSI estimation enable control signal in the second FDD apparatus;
- and upon the CSI estimation enable control signal becoming active, changing the connections of the set of switches so that the receiving frequency band of a receiver in the second FDD apparatus is changed from the normal receiving frequency band F2 to the normal transmitting frequency band F1 and the receiving signal is received from a normal transmitting antenna instead of a normal receiving antenna.
- View Dependent Claims (12, 13, 14, 15)
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16. A method for acquiring the downlink channel information through the reciprocity of wireless channel in a FDD wireless network comprising reserving a time slot in the DL radio resource frame structure in the first frequency band (F1) for one or more UEs to transmit pilot or test signal(s) in the UL direction;
- one or more UEs using the reserved time slot to transmit pilot or test signal(s) in the first frequency band F1;
a BS receiving and using the pilot or test signal(s) to estimate the DL channel information, and performing downlink MIMO beamforming using the estimate of the DL channel information.
- one or more UEs using the reserved time slot to transmit pilot or test signal(s) in the first frequency band F1;
Specification