Method and apparatus of transmitting and receiving system information in a wireless system

A method for receiving system information by a mobile station (MS) of a wireless communication system, the method comprising:

• receiving a secondary superframe header (S-SFH) change cycle from a base station (BS);
• and
• receiving a primary superframe header information element (P-SFH IE) including a first field indicating a change count of a plurality of secondary superframe header subpacket information elements (S-SFH SP IEs) from the BS,
• wherein, once each of the plurality of S-SFH SP IEs is changed, each of the plurality of S-SFH SP IEs remains unchanged during one or more S-SFH change cycle periods, and
• wherein if a difference between a value of the first field and an S-SFH change count stored in the MS is 1, the MS updates an S-SFH SP IE whose bit in an S-SFH change bitmap is set to 1.