08-16-2017, 09:34 PM
Abstract:
Orthogonal Frequency-Division Multiple Access (OFDMA) is a multi-user version. Multiple access is achieved in OFDMA by assigning subsets of subcarriers to individual users. This allows simultaneous low data rate transmission from several users, OFDM is sometimes referred to as discrete multi-tone modulation, instead of a single carrier being modulated, a large number of evenly spaced subcarriers are modulated using some m-ary of QAM. This is a spread-spectrum technique that increases the efficiency of data communications by increasing data throughput because there are more carriers to modulate.In an OFDM system, a very high rate data stream is divided into multiple parallel low rate data streams