Capacity improvement for uplink OFDMA

The combination of OFDM and FDMA, called OFDMA (orthogonal frequency division multiple access), is proposed for future communications systems. The paper studies the problem of receiver design in uplink communications in an OFDMA system. The aim is to provide a receiver design to support efficient resource allocation among multiple users. We look at blind subspace based estimation methods for synchronization and interference cancellation to improve the OFDMA uplink. The paper investigates the performance of the resulting receiver under the conditions of frequency offset and multipath fading. The issues of frequency offset synchronization as well as channel estimation are addressed.