Cooperative ALOHA Protocol in Fading Channels
Date Issued
2009
Date
2009
Author(s)
Chiang, Yi-Han
Abstract
As original MAC protocols are applied in fading channels, the signals transmission may fall in outage and thus the system performance is degraded. To combat this channel impairment, user cooperation providing cooperative diversity has been considered as a promising technology for MAC protocols. Previous efforts on cooperative MAC protocols primarily focus on improving link reliability (Diversity cooperation mode), which ignore that user cooperation can help improve the system throughput as well. To this end, we propose a new cooperative MAC protocol which enables the source to handover its packet to the relay node so that it can turn to cope with its new packets (Multiplexing cooperation mode). In order to apply such concept onto original MAC protocols, so as to enhance the system throughput, we propose cooperative ALOHA protocol (CAP) in fading channels in thesis. However, it is shown that the proposed cooperative MAC protocol benefits to the system performance conditionally. By the complementary properties of the conventional and the proposed cooperative MAC protocol, we observe that there is a tradeoff between the cooperation modes. Therefore, a threshold-based stabilization technique to monitor the aggregate traffic load so as to select cooperation mode accordingly is proposed. Simulation results show that the stabilized CAP can always outperform the conventional ALOHA protocol.
Subjects
Outage
User cooperation
Link reliability
Handover
Stabilization
Diversity cooperation mode
Multiplexing cooperation mode
Type
thesis
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