| 摘要 |
In an OFDM (Fig. 3) or multiple antenna (32) MIMO system, channels are allocated according to the protection provided by a given Low Density Parity Check (LDPC) code (24). An LDPC code is irregular if the functions it comprises do not all act on the same number of variables, ie. if the nodes in its Forney factor graph (Tanner graph) do not have the same number of connections (or "degree"), with a higher variable node degree (VND) representing increased redundancy and protection against channel noise, indicated by Singular Value Decomposition (SVD) gain (28). The VND of various irregular LDPC codes are sorted (Fig. 7 and 8) at a sorter (26) and high VND codes are selected for use in noisier channels according to a precoding algorithm. |
