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For conserving energy, duty cycle is defined by setting up the active and sleep periods of network nodes. In beacon enabled networks, to provide support for duty cycle, the IEEE 802.15.4 standard uses optional super-frame structure. This duty cycle is usually fixed and does not consider the topology changes that often occur in dynamic sensor networks. In this paper, existing energy conserving duty cycling approaches for 802.15.4 networks especially the adaptive duty cycling techniques for wireless sensor networks are summed up. Also, this paper highlights the shortcomings of the proposals in the literature, such as induced additional latency, so that they may not support the practical scenarios of Internet of Things (IoT). Further, this study highlights a gross shortcoming that relative performance comparison of RL-based proposals cannot be performed without using a benchmarking framework and real test-bed environment. In this paper, we have presented the future research directions that would lay the foundation for successful development of energy efficient RL-based duty-cycling techniques.

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An improved data hiding technique is proposed in this paper to hide the shares of a secret image in an Extended Visual Secret Sharing (EVSS) scheme. It is based on Least Significant Bit (LSB) substitution with a little modification that the embedding capacity varies with each pixel of the host image and depends upon the surrounding pixels' color difference. This not only increases the embedding capacity of the host image as compared to simple LSB substitution but also yields high Peak Signal to Noise Ratio (PSNR) values for host and stego images. Moreover, results indicate that the proposed data hiding process improves the security of camouflage images in EVSS schemes since shares are completely hidden in the cover images without any trace of their presence, unlike most of the previous share hiding approaches, thus preventing shares from alteration during transmission.