Patent ID: 9692577
Date: 2017-06-27
CPC Classifications: H04L,H04W

Claim:
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 F 2 from and sends DL signals in frequency band F 1 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 F 2 to the normal receiving frequency band F 1 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 F 2 to the normal transmitting frequency band F 1 and the receiving signal is received from a normal transmitting antenna instead of a normal receiving antenna.