Impact of MAC frame length on energy efficiency in 6LowPAN

To reach necessary end-to-end connectivity between the Internet and wireless sensor networks (WSNs), the Internet Engineering Task Force (IETF) IPv6 over low power wireless personal area network (6LowPAN) working group has been established and introduced an adaptation layer for integration of IEEE 802.15.4 physical layer/media access control (PHY/MAC) layers and the upper layers of any Internet protocol (IP)-based networks, such as the Internet. The energy efficiency is one of the most important performance measures in WSNs because most sensor nodes are only battery powered so we should reduce the energy consumption to the lowest to extend the life of nodes. Therefore the determination of MAC frame length should be carefully considered since that the radio frequency (RF) module consumes most the energy of a sensor node meanwhile the MAC protocol is the direct controller of RF module. In this paper, we provide a star-shaped 6LowPAN non-beacon mode with unslotted carrier sense multiple access with collision avoidance (CSMA/CA) mechanism to access to the channel and model the stochastic behavior of a target end node as the M/G/1 queuing system. Analytical expressions for some parameters such as channel busy probability, packet loss probability and energy efficiency are obtained in this paper and our analytical results can clearly show the impact of MAC frame length on the energy efficiency of a target node in both ideal and lossy channel.