A transmission method comprising: generating a transmission signal for each of a plurality of users, the transmission signal including a plurality of OFDM symbols for a data field which contains an encoded bit stream of information bits, wherein the last OFDM symbol of the plurality of OFDM symbols is partitioned into four segments, the four segments ending with four boundaries, respectively, and wherein the generating of the transmission signal includes: computing, for each of the plurality of users, an initial padding factor value, and computing, for each of the plurality of users, an initial number of OFDM symbols for the data field, wherein the padding factor value represents one of the four boundaries; determining a user with longest encoded packet duration among the plurality of users; determining a common padding factor value that is the initial padding factor value of the determined user with the longest encoded packet duration; determining a common number of OFDM symbols that is the initial number of OFDM symbols for the data field of the determined user with the longest encoded packet duration; adding, for each of the plurality of users, pre-FEC padding bits to the information bits so that the encoded bit stream fills at least one of the four segments until one of the four boundaries specified by the determined common padding factor value; and adding post-FEC padding bits after the encoded bit stream of the last OFDM symbol; and transmitting the generated transmission signal, wherein the user with the longest encoded packet duration is determined based on both the initial number of OFDM symbols and the initial padding factor value of each of the plurality of generating a transmission signal for each of a plurality of users, the transmission signal including a plurality of OFDM symbols for a data field which contains an encoded bit stream of information bits, wherein the last OFDM symbol of the plurality of OFDM symbols is partitioned into four segments, the four segments ending with four boundaries, respectively, and wherein the generating of the transmission signal includes: computing, for each of the plurality of users, an initial padding factor value, and computing, for each of the plurality of users, an initial number of OFDM symbols for the data field, wherein the padding factor value represents one of the four boundaries; determining a user with longest encoded packet duration among the plurality of users; determining a common padding factor value that is the initial padding factor value of the determined user with the longest encoded packet duration; determining a common number of OFDM symbols that is the initial number of OFDM symbols for the data field of the determined user with the longest encoded packet duration; adding, for each of the plurality of users, pre-FEC padding bits to the information bits so that the encoded bit stream fills at least one of the four segments until one of the four boundaries specified by the determined common padding factor value; and adding post-FEC padding bits after the encoded bit stream of the last OFDM symbol; and transmitting the generated transmission signal, wherein the user with the longest encoded packet duration is determined based on both the initial number of OFDM symbols and the initial padding factor value of each of the plurality of computing, for each of the plurality of users, an initial padding factor value, and computing, for each of the plurality of users, an initial number of OFDM symbols for the data field, wherein the padding factor value represents one of the four boundaries; determining a user with longest encoded packet duration among the plurality of users; determining a common padding factor value that is the initial padding factor value of the determined user with the longest encoded packet duration; determining a common number of OFDM symbols that is the initial number of OFDM symbols for the data field of the determined user with the longest encoded packet duration; adding, for each of the plurality of users, pre-FEC padding bits to the information bits so that the encoded bit stream fills at least one of the four segments until one of the four boundaries specified by the determined common padding factor value; and adding post-FEC padding bits after the encoded bit stream of the last OFDM symbol; and transmitting the generated transmission signal, wherein the user with the longest encoded packet duration is determined based on both the initial number of OFDM symbols and the initial padding factor value of each of the plurality of