Orthogonal frequency division multiplexing, Electrical Engineering

Assignment Help:

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 In high mobility scenarios, the orthogonality of the subcarriers is no longer maintained that results in inter-carrier interference (ICI).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


Related Discussions:- Orthogonal frequency division multiplexing

Show output characteristic of common emitter configuration, Q. Show output ...

Q. Show output Characteristic Of Common Emitter Configuration? Output characteristics: This family of curves may be divided into three regions just as was done for common base

Compute product of inductance and capacitance, Q. The inductance per unit l...

Q. The inductance per unit length in H/m for parallel-plate infinitely long conductors in air is given by L = µ 0 d/w = 4π×10 -7 d/w, where d and w are inmeters. Compute L (per un

Determine and sketch il for inductance, Q. For the circuit of Figure, deter...

Q. For the circuit of Figure, determine and sketch i L (t) and vC(t) for inductance values of (a)3/4 H, (b) 2/3 H, and (c) 3/17 H. Note that the inductance values are chosen her

Show a schematic diagram of the seven- segment decoder, Q. Digital watches ...

Q. Digital watches display time by turning on a certain combination of the seven-segment display device. (a) Show a typical seven-segment display. (b) Develop a truth table f

Explain protected mode addressing, Explain protected mode addressing. ...

Explain protected mode addressing. This addressing permits access to data and programs located as the first 1M byte of memory, with in the first 1M byte of memory. Addressing

What is the purpose of clock signal in an 8086 system, What is the purpose ...

What is the purpose of clock signal in an 8086 system? 8086 needs clock signal with 33%duty cycle from some external operations.8086 processor needs 5 MHZ clock signal

What is assembler, What is assembler? Assembler: An assembler or macr...

What is assembler? Assembler: An assembler or macro-assembler usually forms a part of the operating system. This translates an assembly language program into machine language

Sketch the phasor diagram, Q. A balanced delta-connected load with a per-ph...

Q. A balanced delta-connected load with a per-phase impedance of 12 + j9  is supplied by a 173-V, 60-Hz three-phase source. (a) Determine the line current, the power factor, th

Example memory to registers , Example Memory to  Registers Example: ...

Example Memory to  Registers Example: Write  assembly  language  statement  to copy  data byte  36H  stored  at 2025 H  to register B. Solution : Assuming 2025 H is sto

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd