• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.1
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• pp.79-85
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• 2017

Vehicular ad-hoc networks (VANETs) cause link disconnection problems due to the rapid speed and the frequent moving direction change of vehicles. Link disconnection in vehicle-to-vehicle communication is an important issue that must be solved because it decreases the reliability of packet forwarding. From the characteristics of VANETs, greedy forwarding protocols using the position information based on the inter-vehicle distance have gained attention. However, greedy forwarding protocols do not perform well in the urban environment where the direction of the vehicle changes greatly. It is because greedy forwarding protocols select the neighbor vehicle that is closest to the destination vehicle as the next transmission vehicle. In this paper, we propose a greedy anycast forwarding (GAF) protocol to improve the reliability of the inter-vehicle communication. The proposed GAF protocol combines the greedy forwarding scheme and the anycast forwarding method. Simulation results show that the GAF protocol can provide a better packet delivery rate than existing greedy forwarding protocols.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.11
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• pp.2980-2991
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• 2012

Since wireless sensor networks are broadly used in various areas, there have been a number of protocols developed to satisfy specific constraints of each application. The most important and common requirements regardless of application types are to provide a long network lifetime and small end-to-end delay. In this paper, we propose Early Preamble MAC (EP-MAC) with improved energy conservation and low latency. It is based on CMAC but adopts a new preamble type called 'early preamble'. In EP-MAC, a transmitting node can find quickly when a next receiving node wakes up, so EP-MAC enables direct data forwarding in the next phase. From numerical analysis, we show that EP-MAC improves energy consumption and latency greatly compared to CMAC. We also implemented EP-MAC with NS-2, and through extensive simulation, we confirmed that EP-MAC outperforms CMAC.