In an IoT (Internet of Things) network, nodes need first to access the network resources before they can transmit data. If the data to be transmitted require real-time guarantees, then the node should not be stuck in the process of accessing resources. Quick and efficient access to the network resources is desirable for timely data communication. To this end, we have studied the IEEE 802.15.4 and IEEE 802.15.4e-TSCH standards and have proposed energy-efficient algorithms to ensure that the nodes can access the resources at the earliest. We have proposed a “Device Registration” algorithm for IEEE 802.15.4 networks, which aims at increasing accessibility of the Guaranteed Time Slots (GTSs) available in the superframe. The algorithm can be implemented by making minor modifications to the parameters within the existing MAC framework. Similarly, we have proposed a “Sparse Beacon Advertisement”, a beacon scheduling algorithm, for IEEE 802.15.4e-TSCH networks that aims at reducing the wait time for a new node before it joins the network, even when there are few beacons being advertised. Both these algorithms have been evaluated extensively using simulations and experiments on a testbed. Our results show that in an IEEE 802.15.4 network, with the proposed algorithm, nodes are twice as successful in accessing the GTS resources as they were before. Similarly, Sparse Beacon Advertisement reduces the joining times by at least 60% in an IEEE 802.15.4e-TSCH network.

在物联网（IoT）网络中，节点需要先访问网络资源，然后才能传输数据。如果要传输的数据需要实时保证，则该节点不应卡在访问资源的过程中。对于及时的数据通信，期望快速有效地访问网络资源。为此，我们研究了IEEE 802.15.4和IEEE 802.15.4e-TSCH标准，并提出了节能算法，以确保节点最早可以访问资源。我们已经为IEEE 802.15.4网络提出了一种“设备注册”算法，其目的是提高超帧中可用的保证时隙（GTS）的可访问性。可以通过对现有MAC框架中的参数进行较小的修改来实现该算法。同样，我们为IEEE 802.15.4e-TSCH网络提出了一种信标调度算法“稀疏信标广告”，该算法旨在减少新节点加入网络之前的等待时间，即使正在广播的信标很少。这两种算法均已在测试台上使用仿真和实验进行了广泛评估。我们的结果表明，在IEEE 802.15.4网络中，使用提出的算法，节点在访问GTS资源方面的成功是以前的两倍。同样，在IEEE 802.15.4e-TSCH网络中，稀疏信标广告将加入时间减少了至少60％。这两种算法均已在测试台上使用仿真和实验进行了广泛评估。我们的结果表明，在IEEE 802.15.4网络中，使用提出的算法，节点在访问GTS资源方面的成功是以前的两倍。同样，在IEEE 802.15.4e-TSCH网络中，稀疏信标广告将加入时间减少了至少60％。这两种算法均已在测试台上使用仿真和实验进行了广泛评估。我们的结果表明，在IEEE 802.15.4网络中，使用提出的算法，节点在访问GTS资源方面的成功是以前的两倍。同样，在IEEE 802.15.4e-TSCH网络中，稀疏信标广告将加入时间减少了至少60％。