how would i know that how many bits should i sent in an OFDMA signal to meet 10Kbps requirements?

Dear all, i would like to know how many bits should i allocate in an OFDM symbol in order to meet 10kbps requirement. Let me clear it little more. suppose we have 3 different users transmitting (1 voice, 1 video and 1 data user). All these have different requirements in terms of BER and data rate. Voice user is transmitting at 10kbps, video 500kbps and data user 1 Mbps. In one OFDM symbol, i allocate 8 subcarriers to the voice user and on those 8 subcarriers how many bits shud i sent in order to meet 10kbps requirement. Thats it.

Talha

[Walter Roberson]

Unanswerable without knowing the symbol transmission rate.