In this paper, a novel decentralised dynamic sub-carrier assignment (DSA) algorithm for orthogonal frequency division multiple access (OFDMA)-based adhoc and cellular networks operating in time division duplexing (TDD) mode is proposed to solve the hidden and exposed node problem in media access control (MAC). This method reduces the cochannel interference (CCI), and thus increases the overall ...

The wireless industry is in transition. All of the new 4G air-interfaces—WiMAX, Long Term Evolution, Ultra Mobile Broadband, 802.20, Wireless Broadband, next-generation PHS and the like—share some things in common: all are based on OFDM Access (OFDMA); all exploit MIMO; and all have «flattened architecture» and all are Internet Protocol-based. This article discusses WiMAX and LTE: in particular...

Nowadays, OFDMA (Orthogonal Frequency Division Multiple Access) technique has been used in WiMAX communication system to achieve very high data rate as well as multi-user service. However, similar with other OFDM-based systems, OFDMA system is very sensitive to frequency synchronization errors, especially in the uplink communications where different users always have different CFOs (Carrier Fre...

TAMPERE UNIVERSITY OF TECHNOLOGY Master’s Degree Program in Information Technology Samara, Lutfi: Phase Noise Estimation and Mitigation in Uplink OFDMA Master of Science Thesis: 46 Pages October 2013 Major: Communications Engineering Examiners: Prof. Mikko Valkama and Dr. Ville Syrjälä

Successive user detection algorithm is used to observe the multi user ranging signals and calculate there corresponding parameters. Using IEEE 802.16 specification in Orthogonal Frequency Division Multiple Access (OFDMA), initial ranging method designed an algorithm called Moment Maximum Likelihood Detection (MMLD) to detect the codes assigned and predicting offset timing. The objective functio...

Cooperative communication has been proposed to improve the disadvantages of the multiple-input multiple-output (MIMO) technique without using extra multiple antennas. In an orthogonal frequency division multiple access (OFDMA) system, a cooperative communication that each user shares their allocated sub-channels instead of the MIMO system has been proposed to improve the throughput. But the coo...

Cross layer optimization based on utility functions has been recently studied extensively, meanwhile, numerous types of utility functions have been examined in the corresponding literature. However, a major drawback is that most utility functions take a fixed mathematical form or are based on simple combining, which can not fully exploit available information. In this paper, we formulate a fram...