A major drawback of orthogonal frequency division multiplexing (OFDM) is the high peak-to-average power ratio (PAPR) of the transmit signal which can significantly impact power efficiency and performance. In this paper we present a PAPR reduction technique which exploits the phase of the signal in the frequency domain. When used to extend a previous PAPR reduction technique developed by the authors, a PAPR reduction of up to 5 dB can be obtained with this technique giving extremely low out-of-band distortion as well as lower in-band distortion than windowing and clipping methods. There is also no need for side information to be transmitted to the receiver.

A major disadvantage of orthogonal frequency division multiplexing (OFDM) is the presence of high peaks in the transmit signal. These can severely impact amplifier efficiency. Envelope Elimination and Restoration (EER) is an architecture designed for improving efficiency by dynamically adjusting the supply voltage to restore the amplitude on a phase modulated input signal. Although this significantly improves overall efficiency there remains the presence of high peaks in the envelope path, these impact the performance of a sigma delta modulator used in the D/A conversion process as well as overall efficiency. In this paper we describe a PAPR reduction technique which can be employed in order to make the input signal more suited for use with a sigma delta modulator. This causes a reduction in in-band and out-of-band distortion as well as overall efficiency improvement.

One of the major drawbacks of OFDM is its high peak-to-average power ratio (PAPR) which can result in poor power efficiency and serious distortion in the transmitter amplifier. Tone reservation (TR) is a technique designed to combat this problem by reserving a number of sub-carriers (tones) in the frequency domain to generate a cancellation signal in the time domain to remove high peaks. However TR can have a high associated computational cost due to the difficulties in finding an effective cancellation signal in the time domain by using only a few tones in the frequency domain. It also has the disadvantage of reducing data throughput. In this paper we present a PAPR reduction technique for DVB systems which uses a Gaussian pulse as the cancellation signal from only a small number of reserved tones. This facilitates a simple and effective algorithm for reducing peak values while minimizing the occurrence of secondary peaks, the latter being a key factor in contributing to the high computational complexity of tone reservation algorithms. Furthermore, the outlined technique employs some of the unused tones present in a DVB system to form the Gaussian pulse cancellation signal thereby eliminating the reduction in data throughput normally caused by tone reservation.

This article discusses an overview of Top Amplifier Research Groups in a European Team (TARGET), a network of excellence within the Sixth Framework Programme of the European Union created for the purpose of strengthening European research in the field of microwave power amplifiers for broadband wireless access.