Current Issue : January - March Volume : 2021 Issue Number : 1 Articles : 5 Articles
In underwater wireless sensor networks (UWSN), acoustic communication naturally introduces challenges such as long\npropagation delay and high packet loss. The flooding-based routing protocol can address these challenges with its multipath\ncharacteristics. As in flooding-based routing, due to multipath propagation mechanism, not only DATA but also ACK messages\nare transmitted through multiple routes however still some packet loss will degrade the performance. So, to provide high\nreliability of message delivery, an efficient retransmission mechanism is inevitable. Though, if the network uses conventional\ntransport layer protocol such as TCP, it will suffer a spurious retransmission problem as TCP was originally not designed for the\nmultipath environment. In this paper, we propose route discrimination for flooding-based routing to reduce spurious\nretransmission in UWSN to solve the limitation. The notion of ACK copies waiting time (ACWT) is utilized which is selectively\nupdated based on the similarity of paths of transmission of ACK message copies. We also improved our previous solution that\nlacks flexibility to cope with dynamic link error characteristics. Through evaluation, we verified that our new scheme achieves\nthe performance improvements of 14%~84% in terms of retransmission ratio compared to the previous research....
Field observation instruments in cold and arid areas are deployed with many difficulties caused by the harsh natural environment,\nwhich leads to the lag of information acquisition ability and severely restricts the geoscience research in these areas.\nTherefore, it is urgent to study the suitable routing technology of observation instrument networks according to the characteristics\nof cold and arid areas. In this paper, we have studied and designed an improved routing protocol for the field\nobservation instruments network based on the LEACH protocol (FOI-LEACH). Firstly, the FOI-LEACH was proposed to\nmainly improve the LEACH protocol in three aspects: (1) the network nodes are heterogeneous and combined with the\ncharacteristics of field observation instrument networking. The residual energy and the rechargeable energy of nodes are added\nin the process of cluster head (CH) election to reduce the risk of premature death of CHs and shortened network life cycle\ncaused by the selection of nodes with less energy as CH. (2) In the process of cluster forming, the distance from CH to the base\nstation (BS) and the residual energy of CH is considered when setting the cluster radius, to reasonably plan the cluster size and\nalleviate the â??hot spotâ? problem. The nonuniform distribution of clusters in the network is enhanced to balance the total\nnetwork energy consumption. (3) The autonomous zone-based multihop routing mechanism is adopted to solve the low\nreliability of data transmission caused by the poor quality of intercluster communication links and premature death of nodes in\nlong-distance transmission. Then, MATLAB was used to compare the network routing protocol model of the observation\ninstrument from four aspects, network life, energy consumption rate, stability, and throughput. The results showed that the\nimproved algorithm FOI-LEACH balances the network energy consumption and alleviates the â??hot spotâ? problem, to extend\nthe lifetime of network nodes....
In recent years, wireless sensor networks (WSNs) have gained significant attention in both industry and academia. In WSNs, each\nsensor node is normally equipped with a small-size battery with finite capacity. Hence, energy-efficient communication is\nconsidered a key factor for the extension of network lifetime. Formerly, a large number of medium access control (MAC)\nprotocols have been proposed to improve energy efficiency to prolong the network lifetime. There are applications that generate\ndifferent types of data packets and require quality of service (QoS) without any disruption in network operation. Therefore,\nthese applications need an energy-efficient QoS MAC protocol that can support QoS by considering energy efficiency as the\nprimary goal to avoid any failure in the network. This article proposes an energy-efficient asynchronous QoS (AQSen) MAC\nprotocol, called AQSen-MAC. The AQSen-MAC considers different types of data packets and uses two novel techniques: selfadaptation\nand scheduling to enhance energy efficiency, packet delivery ratio, and network throughput. Furthermore, in the\nprotocol, the receiver adjusts its duty cycle according to the remaining energy to prolong the network operation. Finally, the\nperformance of the AQSen-MAC protocol has been evaluated through detailed simulation using Castalia and compared with\nMPQ-MAC, PMME-MAC, and QAEE-MAC protocols. The simulation results indicate that the AQSen-MAC protocol\nsignificantly reduces the energy consumption at the receiver of up to 13.4%, consumption per bit of up to 3% and improves the\npacket delivery ratio and network throughput of up to 12% in the network....
With the development of 5G, the Internet of Vehicles (IoV) evolves to be one important component of the Internet of Things (IoT),\nwhere vehicles and public infrastructure communicate with each other through a IEEE 802.11p EDCA mechanism to support four\naccess categories (ACs) to access a channel. Due to the mobility of the vehicles, the network topology is time varying and thus incurs\na dynamic network performance. There are many works on the stationary performance of 802.11p EDCA and some on real-time\nperformance, but existing work does not consider real-time performance under extreme highway scenario. In this paper, we\nconsider four ACs defined in the 802.11p EDCA mechanism to evaluate the limit of the real-time network performance in an\nextreme highway scenario, i.e., all vehicles keep the minimum safety distance between each other. The performance of the model\nhas been demonstrated through simulations. It is found that some ACs can meet real-time requirements while others cannot in\nthe extreme scenario....
Cloud robotics can largely enhance the robot intelligence by offloading tasks to the cloud dynamically. However, the robots differ in\ntheir own hardware configuration such as battery and processing capacity, while the transmission frames are also a mixture of\ndifferent quality of service (QoS) requirements. As the competition for limited channel resource is inevitable, how to optimize\nthe system performance by effective resource allocation is a key problem. The paper proposes a two-tier hierarchical-based\nMAC (Two-Tier MAC) which means the classification exists not only in frames but also in robots. The Lyapunov optimization\ntechnique is used to maximize the time-averaged quality satisfaction. The experiments show the superior performance of the\nTwo-Tier MAC compared with other MAC protocols especially in overloaded networks. Meanwhile, the system also presents a\nlonger lifetime because the Two-Tier MAC takes energy balance into consideration....
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