About every tenth year a new generation of cellular standards has appeared while 1G system was launched in 1981/1982
. Every generation is differentiated by higher data rates, new frequency bands and non backwards compatible broadcast technology. 4G systems are likely to emerge in 2011-2013 as pre-4G systems like mobile WiMAX and LTE (Long Term Evolution) have already come into view and after 2020 there might be fifth generation systems. The initial release of the 3GPP LTE standard does not totally accomplish the ITU 4G necessities called IMT-Advanced.