However, improving spectral efficiency, as well as enhancing performance for CEU, is still left for an open research issue, especially for Orthogonal Frequency Division Multiple Access (OFDMA)-based 4 th generation (4G) systems.

The resource allocation model for downlink multi-user power communication orthogonal frequency division multiple access spatial division multiple access(OFDMA-SDMA) system is studied with the restrictions of requirement bit number for each user and power upper limit as well as specifically bit number for every subchannel in every orthogonal frequency division multiple(OFDM) symbol.

Focusing on the problem that traditional resource allocation algorithms result in low spectrum efficiency,an adaptive sub-carrier allocation algorithm was proposed for orthogonal frequency division multiple access systems with minimum transmission rate request.

A joint blind estimation method based on spectrum overlap for uplink interleaved orthogonal frequency division multiple access carrier frequency offset and timing synchronization is proposed.

A multicell adaptive resource allocation(MARA) scheme was proposed for downlink orthogonal frequency division multiple access(OFDMA) cellular system.

Built upon OFDM, Orthogonal Frequency Division Multiple Access (OFDMA) is a new wireless access technique.

Introduces the principle of Orthogonal Frequency Division Multiple Access (OFDMA) technology Discusses key technologies about OFDMA used in IEEE 802 16a The results indicate that OFDMA is an optimal solution for 2nd generation Broadband Wireless Access (BWA) network

A cross-layer packet scheduling algorithm is proposed for multi-user MIMO-OFDMA systems with the mixed services, such as Real-Time (RT) and Non-Real-Time (NRT) services.

In 1×3×1 OFDMA cellular system,in order to improve the overall system throughput,a modified algorithm is put forward.