• The KIPS Transactions:PartC
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• v.15C no.2
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• pp.79-86
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• 2008

MANET(Mobile Ad hoc Network) is a collection of two or more nodes equipped with wireless communications and constrained by the factor of energy limitation. The running out of energy on some nodes may bring down the performance of network seriously. For solving the problems above, this paper uses completely separated Node-Disjoint multipaths from a source to a destination as many as possible. And, based on average, minimum or variance of energy values on the each multipath, the packets are distributed on paths. Generally, collecting methods for energy information can be classified into two main categories, Static and Dynamic. As the different energy values collected, the packet distribution methods are classified into six criteria, Static-Average, Static-Minimum, Static-Variance, Dynamic-Average, Dynamic-Minimum and Dynamic-Variance respectively. The performance of the packet distribution methods and that of AODV are compared by NS2 simulation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.10 s.352
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• pp.79-89
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• 2006

TCP is the most widely used transport protocol in Internet applications that guarantees a reliable data transfer. But, in the wireless multi-hop networks, TCP performance is degraded because it is designed for wired networks. The main reasons of TCP performance degradation are contention for wireless medium at the MAC layer, hidden terminal problem, exposed terminal problem, packet losses in the link layer, unfairness problem, reordering problem caused by path disconnection, bandwidth waste caused by exponential backoff of retransmission timer due to node's mobility and so on. Specially, in the mobile ad-hoc networks, discrepancy between a station's transmission range and interference range produces hidden terminal problem that decreases TCP performance greatly by limiting simultaneous transmission at a time. In this paper, we propose a new MAC algorithm for mobile ad-hoc networks to solve the problem that a node can not transmit and just increase CW by hidden terminal. In the IEEE 802.11 MAC DCF, a node increases CW exponentially when it fails to transmit, but the proposed algorithm, changes CW adaptively according to the reason of failure so we get a TCP performance enhancement. We show by ns-2 simulation that the proposed algorithm enhances the TCP performance by fairly distributing the transmission opportunity to the failed nodes by hidden terminal problems.