naa a22 4500 510795102 CHVBK 20180411083333.0 cr unu---uuuuu 180411e20130401xx s 000 0 eng 10.1007/s11277-012-0645-z doi (NATIONALLICENCE)springer-10.1007/s11277-012-0645-z Cooperative Multiuser Relay Communications Employing Hierarchical Modulation [Elektronische Daten] [Roderick Whang, Saransh Malik, Intae Hwang, Huaping Liu] Relay-assisted cooperative communications are a promising solution for error-performance improvement and cell coverage extension. However, additional resources such as time slots or frequency bands are required for the relay, which reduce the overall throughput. This paper proposes two cooperative relay schemes that employ hierarchical modulation to overcome this limitation. One scheme is for symmetric downlink communications and the other is for asymmetric downlink communications. These schemes exploit the hierarchical modulation symbols for users in the network and allow the system to transmit two or more independent data streams simultaneously. The proposed schemes reduce the number of transmission phases to the same as conventional schemes without diversity gain. The symbol-error rates of the proposed systems are a function of the distance parameter of hierarchical modulation. By flexibly controlling the distance parameter based on specific scenarios, it allows an extra degree of freedom to guarantee error performance of receivers whose signals undergo different losses. Springer Science+Business Media, LLC., 2012 Cooperative relay communications nationallicence Hierarchical modulation nationallicence Layered modulation nationallicence Whang Roderick School of Electrical Engineering and Computer Science, Oregon State University, 97331-3211, Corvallis, OR, USA aut Malik Saransh Department of Electronics and Computer Engineering, Chonnam National University, 300 Yongbong-dong, Buk-gu, 500-757, Gwangju, Korea aut Hwang Intae Department of Electronics and Computer Engineering, Chonnam National University, 300 Yongbong-dong, Buk-gu, 500-757, Gwangju, Korea aut Liu Huaping School of Electrical Engineering and Computer Science, Oregon State University, 97331-3211, Corvallis, OR, USA aut Wireless Personal Communications Springer US; http://www.springer-ny.com 69/4(2013-04-01), 1463-1479 0929-6212 69:4<1463 2013 69 11277 https://doi.org/10.1007/s11277-012-0645-z text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11277-012-0645-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Whang Roderick School of Electrical Engineering and Computer Science, Oregon State University, 97331-3211, Corvallis, OR, USA aut NATIONALLICENCE 700 1- Malik Saransh Department of Electronics and Computer Engineering, Chonnam National University, 300 Yongbong-dong, Buk-gu, 500-757, Gwangju, Korea aut NATIONALLICENCE 700 1- Hwang Intae Department of Electronics and Computer Engineering, Chonnam National University, 300 Yongbong-dong, Buk-gu, 500-757, Gwangju, Korea aut NATIONALLICENCE 700 1- Liu Huaping School of Electrical Engineering and Computer Science, Oregon State University, 97331-3211, Corvallis, OR, USA aut NATIONALLICENCE 773 0- Wireless Personal Communications Springer US; http://www.springer-ny.com 69/4(2013-04-01), 1463-1479 0929-6212 69:4<1463 2013 69 11277 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer