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Summary: 1
A Distributed Opportunistic Access Scheme and its
Application to OFDMA Systems
Dandan Wang, Student Member, IEEE, Hlaing Minn, Senior Member, IEEE, and Naofal Al-Dhahir, Fellow, IEEE
Abstract-- Multiuser systems can provide multiuser diversity
gains by assigning channels to users with higher channel gains.
To avoid the extensive information exchange with the access point
for the uplink access in centralized approaches, we propose in
this paper a distributed opportunistic access scheme. Through
a judicious design of a novel backoff mechanism to utilize the
channel information and reduce collisions, significant multiuser
diversity gains are achieved. To a user, the higher the channel
gain is, the smaller the backoff time-slot and, hence, the higher
the access priority of that user is. In addition, for heterogeneous
systems, our proposed scheme can realize multiuser diversity
gains and achieve fairness among the users at the same time.
Finally, we design two distributed opportunistic access schemes
for OFDMA systems. Users contend on all sub-channels in the
first scheme and only on several strongest sub-channels in the
second scheme. Compared with traditional centralized OFDMA
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