HIERARCHICAL CODEBOOK USING WATER – FILLING IN MULTIPATH MM – WAVE MASSIVE MIMO COMMUNICATION

Currently, there are many studies on designing codebook at the transmitter as well as a receiver in the mm-wave MIMO radio communication. One of the codebook designs used is hierarchical codebook design because of its simplicity and effectiveness. It applies to a multi-path transmission environment. With a hierarchical codebook search, the receiver can find the best codewords pair for the transmitter and receiver. We assume that the physical paths change slowly, so the response from the receiver to the transmitter does not require a strict time. However, to improve the channel capacity, the author proposed an extended algorithm to find the codewords using the "water - filling" principle by estimating the gain of physical paths. The results showed that the channel capacity increased significantly compared to the case of a hierarchical codebook search without using the "water - filling" principle.