On the bandwidth efficient constant envelope continuous phase signals

Constant envelope, continuous phase (CECP) signals are widely used in communication systems since they provide better power amplifier efficiency and faster sidelobe roll off. One of the most commonly used CECP signals is the continuous phase modulation (CPM) signal. Even though CPM signals are used in many communication systems, most of them do not provide high bandwidth efficiency. This limits the use of these CPM signals in high rate communication systems, such as digital video broadcast (DVB).; In this work, we first develop a method to evaluate the symmetric information rate (SIR) of a CPM signal transmitted over the additive white Gaussian noise (AWGN) channel. The SIR is used to measure the performance and bandwidth efficiency of the CPM signal. We then derive an upper bound on the asymptotic bandwidth efficiency of CPM, given a signal complexity constraint. This bound leads to our design of bandwidth efficient, low complexity CPM signals. To improve the bandwidth efficiency of a specific CPM signal, we introduce the concept of shaping. It is shown that shaping can improve both the performance and bandwidth efficiency of a CPM signal. In order to enable iterative detection, we develop the soft input soft output (SISO) de-shaper for block and trellis shaping. It is demonstrated that using the SISO de-shaper, together with iterative decoding and de-shaping, the theoretical advantage of shaping can be realized with practical complexity.; In the second part of this work, we derive the capacity of the CECP-AWGN channel under the Carson's rule bandwidth constraint. By comparing the SIR of some existing CECP signals with the channel capacity, it is shown that the bandwidth efficiency of these CECP signals are still far below the CECP-AWGN channel capacity. This motivates us to develop a new CECP signal called phase interpolated modulation (PIM). PIM signals can provide high bandwidth efficiency and fast sidelobe roll off. Furthermore, near optimal performance can be achieved with a very simple receiver structure. Finally, we will show that PIM signals approach the CECP-AWGN channel capacity better than other existing CECP signals.