RAL_SIFS
RAL_SIFS;
3 * RAL_SIFS;
ic->ic_flags) + RAL_SIFS;
sifs = RAL_SIFS - RT2560_RXTX_TURNAROUND;
dur = ural_txtime(RAL_ACK_SIZE, rate, ic->ic_flags) + RAL_SIFS;
ic->ic_flags) + RAL_SIFS;