This paper introduces a new pilot pattern design for channel estimation in WiMAX. Current WiMAX systems use a subcarrier allocation technique known as Uplink Partial Usage of Subcarriers (UL-PUSC). It is based on tile structure that consists of 4 subcarriers by 3 OFDMA symbols with 4 pilots in the corners to aid the channel estimation process. We propose a new pilot pattern called “transposed U...

The improved BER was achieved by inhibiting 1/3 rated Turbo coder instead of 1/2 rated Turbo coder. It was accomplished by sending the output from 1/3 rated Turbo encoder to serial to parallel converter. The output from serial to parallel converter was inhibited to various Adaptive modulation schemes like m-aryPSK, m-aryQAM, m-aryCPM, and m-aryMHPM system. The modulated output was then fed to m...

In this paper, a channel estimation algorithm in frequency domain for IFDMA is introduced. Moreover, a post processing algorithm for further improvement of the channel estimation is presented. The performance of IFDMA is analyzed and compared to DFT precoded OFDMA with blockwise subcarrier allocation with and without frequency hopping in terms of overhead that occurs due to pilot assisted chann...

Most standards for the forthcoming beyond 3G (B3G) and 4G technologies state Orthogonal Frequency-Division Multiple Access (OFDMA) as a very promising candidate to be used as a digital modulation scheme. OFDMA combines multiple access techniques with Adaptive Quadrature Amplitude Modulation (AQAM) to maximize system performance while keeping the errors below a certain target. In order to achiev...

While OFDMA orthogonalizes users within a cell, out-of-cell interference avoidance is a primary concern in the practical implementation of OFDMA systems. This project explores one of the key ideas towards limiting the harmful effects of out-of-cell interference: fractional frequency reuse (FFR) (1). We first explore the idea of frequency reuse and introduce FFR. Then, we discuss the algorithm f...

An adaptive transmission scheme, in which the work in [3] is extended to multiuser environment, is proposed for LDPC-coded MIMO-OFDMA cellular systems that employ FDD by considering active user selection and sub-channel power allocation. The performance of the proposed scheme is obtained from simulation and compared with that of the conventional scheme using mean SNR only. It is shown that the ...

Fractional Frequency Reuse is an interference mitigation technique well suited for OFDMA system where the cell region is partitioned into two: inner cell region and outer cell region. In this paper we proposed an interference mitigation technique in LTE OFDMA femtocell system using Fractional Frequency Reuse (FFR) also system in order to improve performance of the system resource allocation is ...

1 Faculty of Electronics and Telecommunications, Communications Dept. Bd. V. Parvan 2, 300223 Timisoara, Romania, e-mail [email protected] Abstract – The main purpose of this paper is to introduce a blind channel estimation technique based on denoising for multiple access schemes in 3GPP Long Term Evolution (LTE) technology, which uses Orthogonal Frequency Division Multiple Access (OFD...

In the current era of exponentially growing demand for user connectivity, spectral efficiency (SE), and high throughput, performance goals have become even more challenging in ultra-dense 5G networks. The conventional orthogonal frequency division multiple access (OFDMA) tech-niques are mature but not proven sufficient to address data rates increased capacity. Therefore, achieve an improved thr...

Abstract Wireless systems based on Orthogonal Frequency Division Multiple Access (OFDMA) multiplex different users in time and frequency. One of the main problems in OFDMA-systems is the inter-cell interference. A promising approach to solve this problem is interference coordination (IFCO). In this paper, we present a novel distributed IFCO scheme, where a central coordinator communicates coord...