Hi Phani,
Change the code as below.
L_S_RANGE-SIGN = 'I'.
L_S_RANGE-OPT = 'BT'.
L_S_RANGE-low = begdt.
L_S_RANGE-HIGH = sy-datum.
APPEND l_s_range TO e_t_range.
Then if u execute today(20141219), then u will get the data for 20140619 to 20141219.
Regards,
Babu.