1. Conditions and water derivation algorithm
Water-filling algorithm is based on certain criteria, and allocation of transmission power adaptively according to channel conditions, usually better channel conditions in time, multiple power distribution, the channel time difference, the small power distribution, thereby maximizing the transmission rate. Realize the power of "water" assignment, the sender must know the CSI.
1. When the receiver has perfect knowledge of the channel while the transmitting side does not know the signal , the transmit antenna array of the power distribution is a reasonable average .
2. When the transmitting side know the channel, the channel capacity can be increased. For example if when the CSI transmitter is known , it may be employed water-filling to allocate power to each transmit antenna , the power limited case, the water filling principle can MIMO maximizing channel capacity derived.
2. CSI and the total power limited, power allocation algorithm based upon the water filling principle to achieve maximum channel capacity known in the transmitting end
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