tailieunhanh - Báo cáo hóa học: " Research Article Full Rate Network Coding via Nesting Modulation Constellations"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Full Rate Network Coding via Nesting Modulation Constellations | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2011 Article ID 780632 11 pages doi 2011 780632 Research Article Full Rate Network Coding via Nesting Modulation Constellations Suhua Tang 1 Hiroyuki Yomo 1 2 Tetsuro Ueda 1 Ryu Miura 1 and Sadao Obana1 1ATR Adaptive Communications Research Laboratories 2-2-2 Hikaridai Seika-cho Soraku-gun Kyoto 619-0288 Japan 2 Faculty of Engineering Science Kansai University 3-3-35 Yamate-cho Suita Osaka 564-8680 Japan Correspondence should be addressed to Suhua Tang shtang@ Received 30 September 2010 Revised 15 December 2010 Accepted 14 January 2011 Academic Editor Steven McLaughlin Copyright 2011 Suhua Tang et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. Network coding is an effective method to improving relay efficiency by reducing the number of transmissions required to deliver data from source s to destination s . However its performance may be greatly degraded by rate mismatch which is seldom touched in previous works and remains a challenge. In this paper we reinterpret network coding as a mapping of modulation constellation. On this basis we extend the mapping to support full rate network coding FRNC enabling simultaneous use of different modulations by nesting the low level constellation as a subset of the high level constellation. When relay links have different qualities the messages of different flows are combined via network coding in such a way that for each relay link its desired message is transmitted at its own highest rate. The limit in constellation size is also addressed. Compared with the state-of-the-art solutions to rate mismatch the proposed scheme achieves the full rate of all relay links on the broadcast channel. 1. Introduction Wireless communications suffer greatly from .