Studies on the URN scheme for multiple access packet communication systems
Akira Fukuda, Yuji Hasegawa · Electronics and Communications in Japan (Part I Communications) · 1981
Abstract Research on random‐access systems has been mainly based on the ALOHA system. However, such systems have an inherent risk of channel saturation due to the avalanche phenomenon of retransmitted packets. Therefore, several access systems, such as the URN scheme, have been proposed with consideration of adaptability to operational stability and load variation. In this paper we conduct a detailed study of the characteristics of the URN scheme, which is quite attractive in using the concept of direct access instead of random delay. Particularly, we study the influence of errors in estimating the number of packets awaiting transmission and the number of working terminals. It is concluded that these estimations need not be highly accurate. We then propose the H‐URN scheme, which has a slight overhead allowance for state estimation and is simply realizable. It will also be shown that the system characteristics are only slightly degraded compared with the ideal case. Further, the optimally controlled ALOHA system is studied with similar assumptions and methods and it is concluded that the URN scheme is superior in many respects. In addition, brief consideration will be devoted to several points which have not been studied sufficiently (e.g., problems of Ack and comparison with the TDMA system).