Orthogonal frequency division multiplexing, Electrical Engineering

CURRENTLY, orthogonal frequency division multiplexing (OFDM) is emerging as the preferred modulation technique in modern high data rate broadband wireless mobile communication systems. In OFDM, the entire spectrum is divided into subcarriers which are narrow-banded with respec to the coherence bandwidth of the channel. This provides resistance against frequency-selectivity of the channel for wideband data transmission. However, the well known problem in OFDM system is its vulnerability to the frequency offset errors causedby oscillator inaccuracies or the Doppler frequency shift due to mobility. In high mobility scenarios, the orthogonality of the subcarriers is no longer maintained that results in inter-carrier interference (ICI). Hence, the transmission performance of the mobile OFDM system is degraded severely.

ICI cancellation techniques are essential in improving the per formance of OFDM system in an environment which induces frequency offset error. A lot of ICI mitigation methods have been extensively investigated to combat the ICI, including fre- quency-domain equalization, time-domain windowing and the self-cancellation schemes, frequency offset estimation and tracking techniques and so on. Among the methods, the ICI self-cancellation method is a simple way to suppress ICI that uses redundant modulation. Several selfcancellation methods have been exploited, including data conversion, data conjugate and symmetric data-conversion/conjugate methods. Windowing methods reduce the SNR but they need redundant information. That is, the performances of the windowing methods and self-cancellation methods degrade signi?cantly with the increase of frequency offset. Besides, maximum likelihood estimation and extended Kalman

Posted Date: 3/8/2013 12:34:44 AM | Location : United States







Related Discussions:- Orthogonal frequency division multiplexing, Assignment Help, Ask Question on Orthogonal frequency division multiplexing, Get Answer, Expert's Help, Orthogonal frequency division multiplexing Discussions

Write discussion on Orthogonal frequency division multiplexing
Your posts are moderated
Related Questions
Q. A six-pole, double-layer dc armature winding in 28 slots has five turns per coil. If the field flux is 0.025 Wb per pole and the speed of the rotor is 1200 r/min, find the value

(a) The key elements of a protocol are the syntax, semantics and timing. Give a brief explanation of each of these key elements. (b) A file contains 4 million bytes. Compare

Q. Explain about Common Control? Common Control: Those systems in which the control subsystem is outside the switching network are known as common control switching system. Str

CRM Framework There exist several ways to view CRM framework. Therefore, an operational strategic framework is more relevant to apply CRM in power/electricity business systems

Q. Describe the working of bistable multivibrator A bistable circuit is one which can exit indefinitely  in either of two stable states and which can be induced to make an abru

A 2300-V, three-phase, wye-connected, round rotor synchronousmotor has a synchronous reactance of 3 per phase and an armature resistance of 0.25  per phase. The motor operates on

Three sine waves along with frequencies 100Hz, 200Hz and 350Hz and with amplitudes of 1V, 2V and 1.5V correspondingly, are added together to make a single waveform. What is the min

Switching Characteristics During Turn off The techniques  used for turning off a thyristor is known  as  commutation techniques. A  thyristor can be can be  turn off by reducin

Explain graphic adapter and monitor. Video card changes digital output from the computer in an analog video signal and sends the signal by a cable to the monitor also termed a

Determine the node voltage by using KCL: Determine the node voltage V and then current flowing through each element by using KCL. Solution Apply KCL at the node whose