Cellular networks and wireless Internet links transfer ever greater streams of data at increasingly high speed. “Customers expect the performance of networks to improve. At the same time, though, they naturally also expect data transfer to be reliable,” Dr. Elena Costa, who heads up the Beyond 3G mobile phone systems project at Siemens Networks, states. To provide this reliability she turned to coding, especially the Low Density Parity Check (LDPC) codes, which are among the best known channel codes, and introduced some radical improvements.
The principle of coding is basically very simple. Redundant information is added to the original data prior to transmission and can be used to detect and correct errors on decoding. The strength of LDPC codes is in their very high transmission quality and relatively simple decoding. In the past there were two methods available for generating this type of code, the pseudorandom method and the algebraic method, each with its advantages and drawbacks.