A method of generating structured irregular LDPC codes for a wireless network such as a wireless local area network (WLAN) system, allowing systematic generation of improved code ensembles using density evolution, and providing essentially the best tradeoff between decoding threshold and decoding complexity. Such an LDPC code has a higher diversity order for MIMO systems, with better built-in interleaving capability. Further, the code dimension can be tailored to 802.11n system parameters such as the number of sub-carriers and delay. The code also provides an improved girth control scheme, provides flexible length with different expanding factors, and supports simple encoding and shortening for multiple rates.