| 摘要 |
<p>A Multiple Input Multiple Output (MIMO) communication system 1 has a transmitter for transmitting signals over a MIMO Broadcast Channel (MIMO-BC) 6. Data for communication to respective receivers 41, 4K-1, 4K is encoded by encoding stages 101, . . . , 10K-1, 10K in a selected order by selecting codewords c1, . . . cK-1, cK from codebooks C1, . . . CK-1, CK of a nested lattice code. Dither adders 111, . . . , 11K-1, 11K are arranged to add a respective dither d1 . . . , dK-1, dk to the selected codewords c1, . . . cK-1, cK. Quantising stages 121, . . . , 12K-1, 12K each perform respective quantising operations modΛS,1, . . . , modΛS, K-1, modΛS, K using the shaping latticeΛS of the nested lattice code. Quantised signals u1, . . . , uK-1, uK of data encoded earlier in the selected order are output to feedbackward filter stages 141, . . . , 14K-1 for filtering the codewords c1, . . . cK-1, cK of data encoded later in the selected order before they are quantised by the quantising stages 121, . . . , 12K-1 using a feedbackward filter Fb. At the receivers 41, 4K-1, 4K feedforward filter stages 151, . . . , 15K-1, 15K filter received signals y1, . . . , yK-1, yK by applying a feedforward filter Ff. A combination of the feedbackward and feedforward filters Fb, Ff is substantially equivalent to a single filter for extracting the signals representing the data intended to be communicated to the receivers 41, 4K-1, 4K with a minimum mean squared error, but the feedforward filter Ff can be applied by each of the receivers 41, . . . , 4K-1, 4K without knowledge of signals y1, . . . , yK-1, yK received by the other receivers 41, . . . , 4K-1, 4K.</p> |
