How does high peak to average power ratio PAPR affect OFDM system?

How does high peak to average power ratio PAPR affect OFDM system?

In fact, the high PAPR is one of the most detrimental aspects in an OFDM system as it decreases the signal-to-quantization noise ratio (SQNR) of the analog-digital convertor (ADC) and digital-analog convertor (DAC) while degrading the efficiency of the power amplifier in the transmitter.

What is peak to average power?

The “peak to average power” level, usually expressed in dB, is the power level of the highest instantaneous power compared to the average power level. A PAR of 1, or 0 dB, means the signal is of constant power, so the peak power is equal to the average power.

Which of the following can be used to reduce peak to average power ratio?

Abstract: Reduction of Peak to Average Power Ratio (PAPR) in Orthogonal Frequency Division Multiplexing (OFDM) is investigated here. Clipping can be performed in two ways- one is to clip the complex envelopes of OFDM signal and the other is to clip the Inphase (I-signal) and Quadrature phase (Q-signal) independently.

Why OFDM has large PAPR?

The PAPR is rather high in OFDM due to the linear combination of many (pseudo-random) QAM symbols in the IFFT operation (5.3). Hence, due to the central limit theorem, some output OFDM symbols will have very large PAPR. To mitigate this, a DFT precoding of the sequence of QAM symbols can be used.

What are the disadvantages of OFDM?

The main drawbacks of OFDM are its high peak to average power ratio and its sensitivity to phase noise and frequency offset.

How do you reduce PAPR in OFDM?

There are many PAPR reduction approaches for OFDM systems, as clipping, coding, non-linear companding, ton reservation and ton injection, selective mapping (SLM) and partial transmit sequence (PTS) [3].

How do a high peak to average power ratio?

Due to presence of large number of independently modulated subcarriers in an OFDM system, the peak value of the system can be very high as compared to the average of the whole system. This ratio of the peak to average power value is termed as Peak-to-Average Power Ratio. In LTE system, OFDM signal PAPR is approx. 12dB.

What is the best way to reduce the problem of PAPR in OFDM?

In an OFDM system, a large number of subcarriers are used to transmit the modulated symbols and consequently, the OFDM signals have a high peak-to-average power ratio (PAPR). To reduce the high PAPR, we propose a partial transmit sequence (PTS) method based on the adaptive particle swarm optimization.

Why is peak to average power ratio important for OFDM?

Multiplexing (OFDM) is widely used in many digital communication systems such as cellular networks. OFDM is known to provide high data rates, strong resistance to multipath effects, and high spectral efficiency. However, the transmitted signal suffers from a high Peak-to-Average Power Ratio (PAPR) which degrades the signal.

Why is the PAPR so high in OFDM?

The PAPR is rather high in OFDM due to the linear combination of many (pseudo-random) QAM symbols in the IFFT operation (5.3). Hence, due to the central limit theorem, some output OFDM symbols will have very large PAPR. To mitigate this, a DFT precoding of the sequence of QAM symbols can be used.

What is the peak to average power ratio?

To keep the average power the peak power of the remaining signal is N times the average power. When OFDM subcarriers add up coherently the power of the transmitted signal is N times the average power. The Peak-to-average power ratio (PAPR) of is the number of subcarriers.

Is the PAPR the same as the power ratio?

It should also be noted that PAPR can be defined as power-to-average power ratio, but sometimes the term peak-to-average power ratio is used. In the former case, the statistical distribution of the power-to-average power ratio is generated and the PAPR is thus a statistical distribution function.