Nowadays, tons of sensors are used to monitor our surrounding environment. Sensors can be utilized at an extensive scale to monitor and connect all sorts of devices in a smart grid based on an anywhere/anytime/anything style. Connecting all sorts of devices needs some efficient addressing methods to address all kinds of objects in the IoT. Integrating cloud computing with the Internet of Things (IoT) in a huge data network can also facilitate smart management of energy for currently-growing populations worldwide.
On the other hand, tremendous communication loads and huge data transmission are energy-intensive. Moreover, quality communication on the Internet of energy relies on numerous field-deployed actuators and sensors.
As a key component of this smart infrastructure, the low-cost, structurally-simple wireless sensor nodes applicable to an extensive range of deployment scenarios can assist with realizing monitoring in smart grids. Moreover, wireless sensor networks (WSNs) normally comprise small sensors with limited radio transmission, processing power, and data storage resources. Their common applications include smart grids, surveillance, home, and industrial automation, environmental monitoring, and social networks, including mobile social networks.
Limited power supply constitutes the most significant constraint in WSNs. Given the practical infeasibility of replenishing energy in the majority of WSN applications, designing energy-efficient systems with a long lifetime is a major challenge. A large body of literature is devoted to energy optimization mainly by employing routing algorithms in WSNs as well as MAC optimization, data fusion, and cross-layer optimization that combines multiple levels.
As a commonly-used method, quorum sensing is utilized to design wireless network protocols.
Quorum-based systems mainly rely on sensor nodes for functional switching between units of sensing and communication in an on-off cyclic manner. The amount of energy consumption by active nodes can be lower by more than one-tenth by switching them to the sleep mode.
All of the quorum-based protocols divide time into intervals known as quorum intervals. Each of these intervals contains equal beacon intervals during which a station can sleep or stay awake. Quorum systems define cyclic patterns as wakeup-sleep schedules during n consecutive beacon intervals, with integer referring to the system size. In addition, the strengths of these protocols lie in the facts that stations ought to be awake in only out of beacon intervals, and at least two stations remain awake during every beacon interval. Increasing the number of active slots known as quorum time slots enhances the likelihood of the forwarder set of nodes being inactive states during their data transmission, which lowers transmission delays. In addition, the energy consumed by an active node is 100-1000 times that consumed by a sleeping node. The number of quorum time slots, therefore, negatively relates to the lifetime of nodes. Given the challenging design and development of quorum time slots in quorum-based protocols, available methods suffer limitations as follows:
– Energy efficiency: Energy holes emerge in WSNs causes by the feature of data collection when the energy consumption close to a sink is significantly higher than the energy consumption far from the sink. Thereby, the nodes’ battery close to the sink drains much faster than other nodes, which causes the death of the network. Utilizing the same quantity of quorum time slots for different nodes in current quorum-based protocols causes the emergence of energy holes in networks. Aiming at energy saving, decreasing these slots in number for the nodes carrying fewer data in areas far from a sink lowered energy efficiency and increased the remaining energy.
– Few intersection slots: Quorum-based protocols independently select slots as quorum slots through nodes. At least one intersection slot between different nodes must be guaranteed for data transmission. One of the main aims in designing quorum-based protocols is to increase the number of intersection slots between nodes to minimize the network latency; nevertheless, currently-applied methods ensure few intersection slots between 2 adjacent nodes. Overcoming the obstacles facing current quorum-based protocols is, therefore, crucial in terms of increasing their small intersection slot ratios.
– Prolonged transmission latency: Network transmission latency refers to the interval between sensing the data produced by a node and transmitting the data to a sink. The lower the transmission delay, the more accurate and reliable results. Event monitoring in a specific region constitutes the main role of a WSN. Commonly-used quorum-based protocols suffer many limitations. Many researchers quantitatively reduced quorum slots of nodes to reduce energy consumption in a network, which was, however, associated with fewer intersection slots between nodes. In the case of data transmission by a node, the delay of a sensing node in the detection of the next-hop node in routing will be therefore long, leading to prolonged transmission latency. Further studies are therefore recommended to be conducted to decrease network latency while ensuring network lifetime.
In this paper, we propose two new quorum-based protocols, called Adaptive Stepped-Grid (AS-Grid), for minimizing delay and maximizing neighbor sensitivity and Low Power Stepped-Grid (LPS-Grid) for minimizing active ratio and maximizing the network lifetime for wireless sensor networks (WSNs). In this paper, the main contributions are as follows:
The proposed protocols increase/decrease the Expected Quorum Overlapping Size (EQOS)/active ratio, which increases/decreases the number of intersection slots/the Quorum Slots Size (QSS), to maximize neighbor sensitivity and minimize delay and minimize power consumption. In most existing quorum-based protocols like grid, torus, e-torus, cyclic, and FPP, the neighbor sensitivity is low and causes high latency in sending/receiving data between nodes. In this paper, we devise two new quorum systems that have comparably high neighbor sensitivity than grid, cyclic, torus, e-torus, and FPP. Another merit of these two protocols is that unlike existing quorum-based protocols, these two protocols are flexible in system size and works with any array size. While the grid works with just arrays, the torus and the e-torus works with just arrays when , and the cyclic and the FPP can only be constructed when and is a prime power.
In existing Quorum Systems, the active slots are randomly allocated to nodes in the network. But in the AS-Grid protocol, active slots are allocated to nodes based on the conditions of the nodes adaptively. In wireless sensor networks, data are collected and transmitted from areas that are far away from the sink or Cluster Heads (CH) nodes to the CH nodes or the sink. Thus, those nodes in areas that are close to the sink or CH nodes need more active slots, while the nodes in areas that are far away the sink or CH nodes need less active slots to transmit data. This adaptive approach of allocating active slots can consume less energy and prolong the network lifetime. The AS-Grid protocol increases neighbor sensitivity, thereby decreases the network latency. The LPS-Grid protocol decreases active ratio, thereby decreases power consumption and extend the lifetime of the network.The results show that neighbor sensitivity and power consumption can be improved through our theoretical analyses.