The optimal number of sub-carriers for three randomly interfering OFDM systems

In this paper, we derive analytical equations for the optimal number of sub-carriers to maximize average channel capacity in an OFDM system. In OFDM systems, since each sub-carrier with a modulated QAM symbol is transmitted, the more sub-carriers are allocated to users, the more improved is the transmission rate. However, in interference-limited environments, because the allocated sub-carriers can interfere with the neighboring OFDM systems, channel capacity decreases based upon the number of allocated sub-carriers. Due to this, in the trade-off relationship between the number of allocated sub-carriers and the interference probability among sub-carriers, average channel capacity can be optimized by selecting optimal number of sub-carriers.