OFDMA is one of the promising candidates for wireless communication. In the subcarrier mapping, the two most important subcarrier mapping techniques namely Interleaved and Localized mapping techniques are being considered. OFDMA is a method that assigns different groups of subcarriers to different users. When an interleaved technique is implemented with OFDMA, it is known as interleaved OFDMA (...

Transmitting images over an Orthogonal Frequency Division Multiplexing Access (OFDMA) system poses a significant challenge. The process entails sending substantial amount of data, which consumes bandwidth. Consequently, compressing the transmitted image becomes essential to reduce required aim this paper is examine and analyse wireless transmission compressed via Discrete Cosine Transform (DCT-...

Orthogonal frequency-division multiple access (OFDMA) gains increasing attention for broadband, high data rate wireless communications. In this paper, we develop a novel unitary precoded (UP) OFDMA scheme that is particularly appealing for the uplink, because it offers high bandwidth efficiency, and constant modulus transmissions for each user. Theoretical analysis of UP-OFDMA with channel codi...

To improve the uplink performance of wireless network for long term evolution (LTE) single carrier frequency division multiple access (SC-FDMA) and orthogonal (OFDMA) are used. Two major concerns these SC-FDMA OFDMA high peak-to-average power ratio (PAPR) efficient subcarrier mapping scheme. This paper presents a comparison under different schemes which includes localized FDMA (LFDMA), distribu...

Quadrature orthogonal frequency division multiple access (Q-OFDMA) systems have been recently proposed to reduce the peakto-average power ratio (PAPR) and complexity, and improve carrier frequency offset (CFO) robustness and frequency diversity for the conventional OFDMA systems. However, Q-OFDMA receiver obtains frequency diversity at the cost of noise enhancement, which results in Q-OFDMA sys...

High peak-to-average power ratio (PAPR) reduction is one of the major challenges in orthogonal frequency division multiple access (OFDMA) systems since last decades. High PAPR increases the complexity of analogue-to-digital (A/D) and digital-to-analogue (D/A) convertors and also reduces the efficiency of RF highpower-amplifier (HPA). In this paper, we present a new DiscreteHartley transform (DH...

The main aim of the project is to study the effect of the variation of major parameters on OFDMA systems and to find channel estimation for CDMA/OFDMA communication systems, in which the bit/symbol error rate of a time varying channel has to be estimated in order to correct the channel interference prior to the decoding of information symbols. Also to propose a system that makes full use of the...

This paper presents a new subband allocation scheme for multiuser OFDMA systems. Adaptive OFDMA systems have focused on adapting the allocation of subcarriers and power to the instantaneous channel conditions of all users. Using frequency hopping pattern in OFDMA system allow users to minimize intercell and intracell interference, and perform frequency diversity. In contrast to conventional FH-...

The performance of Orthogonal Frequency Division Multiple Access (OFDMA) system degrades significantly in doubly dispersive channels. This is due to the fact that exponential sub-carriers do not match the singular functions of this type of channels. To solve this problem, we develop a system whose sub-carriers are chirp functions. This is equivalent to exploiting Fractional Fourier Transform (F...

Frequency-hopping (FH) methods in the Orthogonal frequency division multiplexing access(OFDMA) system,which are to assign user-specific subcarrier to the active users, have been paid much attention to in the broadband wireless communication system. In this paper, we present a novel multiple access scheme, referred to as CDM-FH-OFDMA, which is the extension of FH-OFDMA with code division multipl...