The Research Of Physical Layer Network Coding Strategy Based On Various Modulation Techniques

Under the circumstances that two or more users in a wireless network transmit simultaneously, their electromagnetic signals will be linearly superimposed on the channel. As a consequence, a receiver that is interested in one of these signals will be interfered by the others. However, with a recently developed physical layer network coding strategy, by using the concept of network coding to physical layer, interference can be harnessed and the throughput will be significantly elevated. This paper explores the physical layer coding strategy based on PSK, DPSK and QAM as well as using MAP to evaluate the system performance.Targeting at high order modulation, for the purpose of avoiding inter-symbol interference and code words shortage in larger constellation cases, lattice coding, due to the excellent performances on signal and channel coding as a linear code word, and the perfect match with physical layer coding demands, is adopted. This paper explores and applies the nested lattice code words in physical layer network coding scheme, and obtains a coding and decoding scheme that can approach the Gaussian channel capacity. This paper compares this compute-and-forward relay scheme with traditional relay schemes and proves the superiority of the lattice physical layer network coding performance.