Constant-Envelope Modulation Schemes with Turbo Coding

The communication infrastructure is one of the biggest energy consumers in the world. With the expected exponential growth in the demand for wireless traffic, it becomes the foremost priority to make the communication systems energy-efficient. In this work, we will explore two energy efficiency enhancement techniques: Constant-Envelope modulation and Turbo coding. In Constant-envelope modulation, the high Peak-to-Average Power Ratio (PAPR) signal is transformed into a constant-envelope phase modulated signal. Thus the PAPR of the signal reduces to 0 dB, enabling the power amplifiers at the transmitter to work at the energy-efficient operational point. The second technique known as Turbo coding, has been known to perform very close to the theoretical bounds. Thus when Turbo codes are applied on a modulation scheme, there is a significant improvement in bit-error-rate performance. Consequently, the number of retransmissions is decreased which helps to conserve power at the transmitter.In this thesis, we will explore the application of these two established techniques for the modulation schemes used in 3GPP LTE standards: Orthogonal Frequency Division Multiplexing (OFDM) and Single Carrier-Frequency Division Multiple Access (SC-FDMA). We will also present their comparisons in terms of bit-error-rate and spectral efficiency