*Phase Noise in OFDM DOI: http://dx.doi.org/10.5772/intechopen.105551*

transmitting over the channel. The 64-point FFT of the received signal is taken after CP removal. Simulation model is based on IEEE 802.11 g like system with parameters given in **Table 2**.

**Figure 6.** *Received constellations in 16-QAM OFDM system with (a) receiver phase noise and (b) transceiver phase noise.*

## **5. OFDMA**

In OFDMA system, both the time and frequency resources are used to separate the multiple users. As OFDMA is typically used with burst transmission, a burst consists of many OFDM symbols. In an OFDM symbol, there are many subcarriers. So, a subcarrier in frequency domain and symbol duration in time domain are the finest units. The combination of a time unit and a frequency unit, i.e., a symbol period and a
