The adaptive PSAM design in cross-layer

The purpose is to design the pilot symbols efficiently and adaptively in communication systems to guarantee the minimum channel estimation error and the required quality of service (QoS). The various adaptive schemes about pilot symbols assisted modulation (PSAM) are obtained in terms of the pilot-insertion frequency and the power arrangement. The pilot-insertion frequency is redefined according to the sampling theory and the characteristics of fading channels, such as the level crossing rate (LCR) and the average fading duration (AFD). The power arrangement is optimized by maximizing the average spectral efficiency (ASE) in cross-layer design system. Besides, the ASE function in such a system is modified taking the imperfect channel state information caused by channel estimation into considered. The closed-form expression of modified ASE is present in this paper. From both the theoretical analysis and simulation points of view, a suitable scheme about PSAM design is obtained for cross-layer design.