Orthogonal Frequency Division Multiplexing (OFDM) is an emerging multicarrier modulation scheme, which has been adapted for several wireless local area network (WLAN) systems and IEEE 802.16a (WIMAX) systems. The quality of service and performance sensitivity of different wireless services varies according to the channel, so the conventional OFDM is unsatisfactory. In this paper, we introduce an adaptive modulation scheme in association with OFDM systems. By using different modulation techniques we can send variable number of bits per symbol depending on the channel quality to achieve better throughput. We also remove the pilot bits from the transmitted data to increases the bandwidth efficiency. We propose a method to estimate the channel quality and Signal-to-Noise ratio (SNR) directly, without using any pilot bits. © 2012 Springer-Verlag.