Time-slotted channel hopping (TSCH) medium access control is a promising technology for the construction of reliable large-scale smart metering networks. However, the existing TSCH scheduling methods do not meet the requirements of large-scale smart metering applications. In particular, link throughput limits exist, which yield packet latency and buffer overflows. In this paper, we propose a static TSCH scheduling scheme that permits all nodes in the TSCH network to transmit or receive frames in any slot. To reduce network control message collisions, we define the broadcast slots and unicast slots individually. To assess the performance of the proposed TSCH scheduling scheme, an evaluation is performed in a real-world testbed. The proposed scheduling scheme achieves a high packet delivery ratio (PDR), even in large-scale and densely deployed networks. In most scenarios, the reliability required by smart metering services is achieved. In a 100-node network, in particular, the proposed scheduling method achieves a PDR exceeding 99%, even when 350-byte packets are collected every 60 s. The scheme and results reported in this study have potential application as guidelines for implementation of large-scale TSCH-based smart metering networks.INDEX TERMS Internet of things (IoT), smart metering networks, time slotted channel hopping (TSCH) scheduling, wireless sensor networks.

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We present a new infrastructure to support secure and energy-efficient multicast communication for both innetwork processing and mobility in WSNs. A level-based hierarchy is used for the design. It subdivides the group ( | ll routing tree into level and branches. On top of it, the Secure Secure Pakcet Forwarding (SPE) D,E,F:Sensing Data Packet Forward (SPF) scheme and re-keying algorithm are -SPF-ACK B Aggregating Dataimplemented. The Secure Packet Forward (SPF) mechanism efficiently detects and mitigates the Byzantine behavior as Figure 1. Secure Packet Forwarding avoiding interference between data aggregation and message encryption. The re-keying algorithm effectively handles the impact of mobility on key establishment while minimizing the number of messages to be exchanged. Simulaaggregation. If an adversary can obtain the cryptographic tion results show that the proposed approach can derive the keys from a compromised intermediate node (aggregator) benefits of in-network processing with reasonable routing and reprogram it with malicious code, it can modify, forge overhead minimizing the effects offaulty nodes. Moreover; or discard messages, or simply transmit false aggregation it achieves dramatically lower overhead than traditional sevalues. Thus one compromised node is able to significantly cure multicast protocols for mobility management.alter the final aggregation value. However, identifying and isolating aberrant nodes that are serving as intermediate nodes is challenge issue.

We have developed a secure, accurate and energy-efficient time synchronization protocol (SAEP). First, SAEP achieves accurate time synchronization service with significantly reducing the number of message exchanges. Second, SAEP safeguards Byzantine failure, in which nodes drop, modify, or delay time information in an attempt to disrupt the time synchronization service in multi-hop networks. SAEP takes a distributed approach where each sensor independently makes decisions based only on the information collected from multiple adjacent nodes, thus achieving a high level of resistance to various attacks at a minimizing energy cost. In our experiment SAEP outperforms the existing time synchronization protocol in accuracy, energy consumption, and it is even resilient to multiple capture attacks.