An efficient MAC protocol in wireless ad-hoc networks with heterogeneous power nodes

A simulation study of a MAC layer protocol for wireless networks with asymmetric links

“…Fujii et al [2] made several improvements relative to [1]: (i) not only CTS but also RTS packets are rebroadcasted; (ii) nodes with a CTS packet to rebroadcast, first sense the medium and transmit only if the medium is not busy; and (iii) only high-power nodes rebroadcast RTS or CTS packets. The solutions proposed by [1] and [2] can lead to the inefficient use of the channel if nodes are misclassified as hidden nodes. In such situations, nodes that could have been active are silenced due to misclassification, severely degrading the channel utilization.…”

“…In such situations, nodes that could have been active are silenced due to misclassification, severely degrading the channel utilization. [1] and [2] routinely assume routing over symmetric links so that the sender is able to receive both CTS and ACK packets. In the presence of asymmetric links, however, the sender might not receive the CTS or ACK packets, thus the sender cannot trigger the transmission of DATA packets, and does not know whether a transmission was successful or not.…”

“…In this way, a considerable number of nodes that are misclassified as "hidden" nodes by [1], referred to as protocol A, and [2], referred to as protocol B, are allowed to transmit. Note that our approach does not identify all hidden nodes, but neither methods A or B are able to identify all hidden nodes.…”

“…We compare the accuracy of the classification of our proposed AMAC protocol with the accuracy of two well known protocols which are performing the same classification [1,2]. As a note, the basic IEEE 802.11 MAC protocol does not perform any classification of nodes.…”

“…The MAC layer protocol requires fewer nodes to maintain silence during a transmission than the protocols proposed in [1,2]. We introduce a set of metrics characterizing the ability of a MAC protocol to silence nodes which can cause collisions.…”