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 Enhancing the Performance of Random Access Networks with Random Packet CDMA and Joint Detection | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2009 Article ID 238103 16 pages doi 2009 238103 Research Article Enhancing the Performance of Random Access Networks with Random Packet CDMA and Joint Detection Roland Kempter 1 Peiman Amini 2 and Behrouz Farhang-Boroujeny2 1Military Air Systems EADS Deutschland GmbH 88039 Friedrichshafen Germany 2Department of Electrical and Computer Engineering University of Utah UT 84112 USA Correspondence should be addressed to Roland Kempter kempter@ Received 17 January 2008 Revised 17 April 2008 Accepted 29 July 2008 Recommended by Petar Popovski Random packet CDMA RP-CDMA is a recently proposed random transmission scheme which has been designed from the beginning as a cross-layer method to overcome the restrictive nature of the Aloha protocol. Herein we more precisely model its performance and investigate throughput and network stability. In contrast to previous works we adopt the spread Aloha model for header transmission and the performance of different joint detection methods for the payload data is investigated. Furthermore we introduce performance measures for multiple access systems based on the diagonal elements of a modified multipacket reception matrix and show that our measures describe the upper limit of the vector of stable arrival rates for a finite number of users. Finally we simulate queue sizes and throughput characteristics of RP-CDMA with various receiver structures and compare them to spread Aloha. Copyright 2009 Roland Kempter 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. 1. Introduction Generally channel access can be performed either in a centrally controlled or distributed fashion. The benefit of scheduled access is obvious due to the all-knowing nature of the channel arbiter .
