research centers


Search results: Found 2

Listing 1 - 2 of 2
Sort by

Article
OFDM Channel Estimation Enhancement using Null Subcarriers

Author: Abdulmunem Ahmed Mohammed
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2018 Volume: 25 Issue: 1 Pages: 12-17
Publisher: Tikrit University جامعة تكريت

Loading...
Loading...
Abstract

Orthogonal frequency division multiplexing (OFDM) is one of the popular techniques for high data rates nowadays. However, the channel transfer function estimation for OFDM based systems is essential, to increase the bit rate with low bit error rate (BER) degradation. Numerous algorithms are provided in the literature such as the pilot assisted channel estimation methods. This paper suggests to making use of the null subcarriers, such as the cyclic prefix interval, to make more occupation of the pilot subcarriers. Least squares estimator has been employed to estimate the channel frequency response. However, simulation results, using MATLAB programming, show that the BER performance has been improved, where the required signal to noise ratio (SNR) has been reduced by approximately 4dB, for different baseband mapping.


Article
Select the Best Cyclic Prefix for Various Effective Area in an O-OFDM System

Authors: Rend N. Alrays --- Razi J. Al-azawi --- Sinan Majid
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2018 Volume: 36 Issue: 5 Part (A) Engineering Pages: 488-492
Publisher: University of Technology الجامعة التكنولوجية

Loading...
Loading...
Abstract

In the past few years, the Optical Orthogonal Frequency Division Multiplexing (O-OFDM) has been deliberated as a promising future in high data transmission technology. OFDM is a special case of FDM technology, which is a multi-carrier-modulation (MCM). OFDM has been developed in the wireless as well as wireline systems, for that reason it is popularly used in optical transmission systems. O-OFDM system is simulated with Optisystem V14.0 program from @Optiwave company. This paper provides an examination of O-OFDM system using different cyclic prefix length to eliminate the effect of ICI and ISI, on the other hand using different values of effective area of the optical fiber and observe its effect on the bit error rate of the system. The best transmission performance (best BER) at a length of 1000Km of optical fiber of the system is at a cyclic prefix of 1/16 (6.25%) at the effective area of 150 μm2.

Listing 1 - 2 of 2
Sort by
Narrow your search

Resource type

article (2)


Language

English (2)


Year
From To Submit

2018 (2)