How WCDMA Interleaving ?

Effect
  • Interleaving is used to reduce the probability of consecutive bits error
  • Longer interleaving periods have better data protection with more delay
  • Channel coding works well against random errors, but it is quite vulnerable to bursts of errors, which are typical in mobile radio systems. The especially fast moving UE in CDMA systems can cause consecutive errors if the power control is not fast enough to manage the interference. Most coding schemes perform better on random data errors than on blocks of errors. 
  • This problem can be eased with interleaving, which spreads the erroneous bits over a longer period of time. By interleaving, no two adjacent bits are transmitted near to each other, and the data errors are randomized. 
  • The longer the interleaving period, the better the protection provided by the time diversity. However, longer interleaving increases transmission delays and a balance must be found between the error resistance capabilities and the delay introduced.