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EXISTING SYSTEM

PROPOSED SYSTEM

EXISTING CONCEPT

we average the conditional BER over the fading statistics. Our analysis shows that the BER for an uncoded OFDM system with quadrature amplitude modulation (QAM) can be obtained as the sum of a few integrals, whose number depends on the constellation size. Each integral can be computed by numerical techniques, or, in Rayleigh fading, replaced by a series expansion that involves generalized hypergeometric functions.

PROPOSED CONCEPT

Here, each estimator variance depends on the training sequence size and the pilot power. In this paper, variable and fixed pilot power are considered. When the pilot power equals the signal power, the estimator accuracy improves as SNR increases.

assuming that the pilot power is fixed regardless of the signal power. This assumption is commonly used when no explicit expression is available for the estimator variance.

EXISTING TECHNIQUE:

Non-random CFO

PROPOSED TECHNIQUE:

Cyclic prefix based CFO technique

Training symbols based CFO

Fixed and equal pilot power.

TECHNIQUE DEFINITION:

It is common in most previous research to measure the performance degradation due to non-random CFO in terms ofthe average signal-to-interference plus noise ratio (SINR).

TECHNIQUE DEFINITION:

Taking into account accurate statistical models for the ICI, new exact expressions for the spectral efficiency of OFDM systems in the presence of residual CFO.

DRAWBACKS

Performance degradation due to non-random CFO in terms of the average signal-to-interference plus noise ratio (SINR).

ADVANTAGES

spectral efficiency increases with SNR without bound.