In this paper

an energy-saving method based on cell discontinuous transmission（DTX） technique for LTE system is presented.By using cell DTX

the cell can be put into sleep mode and the power amplifier（PA） can be turned off in certain OFMD symbols

which do not carry any user information or control signals.An optimization model is proposed

to get the number of sub-frames that can enter sleep mode in a system frame

according to the traffic load.The optimized object of the model is PA energy consumption

which is more effective than only taking the channel transmission energy into consideration.It is showed that

significant energy reductions can be achieved by using cell DTX technique

when the traffic load is low.Taking a single user system as example

up to 60% energy reduction of PA energy consumption can be achieved.