Abstract:
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Accurate representation of the physical layer is
instrumental for a sound design and optimization of Medium Access
Control (MAC) protocols for cooperative wireless networks.
However, the vast majority of MAC protocols are designed and
analyzed by considering simplified physical layer and channel
models, which often lead to too optimistic performance predictions.
In particular, even though many experimental activities
have showcased the important role played by shadow-fading,
most protocols are designed and evaluated by taking into account
only the transmission distance (circular coverage model) or only
the fast-fading. Motivated by the proved unsuitability of these
models, the contribution of this paper is threefold: i) we provide
important considerations on how to adequately include the effect
of shadowing into the design of MAC protocols for cooperative
networks; ii) we provide an analytical framework to determine
the subset of active relays in order to meet a given Quality-of-
Service (QoS) requirement; and iii) we study, through analysis
and simulation, the performance of a promising MAC protocol
for cooperative networks, which is called Persistent Relay Carrier
Sensing Multiple Access (PRCSMA), by explicitly taking into
account the effect of shadowing. Our study shows that shadowing
can dramatically change system and protocol performance |