fig8 the extended subheader group consists of an extended subheader lengths field 81 for providing a total length of the extended subheader group a reserved bit field 82 an extended subheader type field 83 and an extended subheader body 84 preferably the extended subheader lengths field should be represented in 8 bits and the total length of the extended subheader is represented in bytes here the total length can be represented by maximum of 27 bytes furthermore there can be up to 128 types of extended subheaders here table 5 illustrates addition of two extended subheaders that is based on the extended subheader type field 83 a type corresponding to u2018 0 u2019 has an extended subheader u2014 1 having a length of one 1 byte while a type corresponding to u2018 1 u2019 has an extended subheader u2014 2 having a length of two 2 bytes depending on the type the extended subheader can be classified into whether the subheader is for uplink or downlink transmission for example a subheader used in the uplink is formed at the ms and transmitted to the bs and if the ms receives this subheader the ms disregards it fig9 is an example of a format of an esf here refer to fig7 and 8 as well as table 2 in fig9 the mac pdu includes the extended subheader group and an extended subheader length field 91 is used to indicate a total length of the subheader s in this figure the total length of the subheaders is six 6 bytes in detail a new extended subheader u2014 1 includes a reserved bit 92.