Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Design of Uniformly Most Powerful Alphabets for HDF 2-Way Relaying Employing Non-Linear Frequency Modulations | Hekrdla and Sykora EURASIP Journal on Wireless Communications and Networking 2011 2011 128 EURASIP Journal on http content 2011 1 128 Wireless Communications and Networking a SpringerOpen Journal RESEARCH Open Access Design of Uniformly Most Powerful Alphabets for HDF 2-Way Relaying Employing Non-Linear Frequency Modulations Miroslav Hekrdla and Jan Sykora Abstract Hierarchical-Decode-and-Forward is a promising wireless-network-coding-based 2-way relaying strategy due to its potential to operate outside the classical multiple-access capacity region. Assuming a practical scenario with channel state information at the receiver and no channel adaptation there exist modulations and exclusive codes for which even non-zero channel parameters denoted as catastrophic cause zero hierarchical minimal distance -significantly degrading its performance. In this work we state that non-binary linear alphabets cannot avoid these parameters and some exclusive codes even imply them contrary XOR does not. We define alphabets avoiding all catastrophic parameters and reaching its upper bound on minimal distance for all parameter values denoted uniformly most powerful UMP . We find that binary non-binary orthogonal and bi-orthogonal modulations are UMP. We optimize scalar parameters of FSK modulation index and full-response CPM frequency pulse shape to yield UMP alphabets. I. Introduction Cooperative communication in wireless relay networks can potentially be of great benefit offering several gains that may decrease required transmission power increase the system capacity improve the cell coverage or interference mitigation while balancing the quality of service and keeping relatively low deployment costs 1 . Consequently future wireless networks are envisaged to include the cooperative relaying techniques. However it also brings several new challenging problems such as the extra resources . frequency or time slots taken for interference-free relay traffic .
