International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 04 Issue: 07 | July -2017
p-ISSN: 2395-0072
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Modified PREQ in HWMP for Congestion Avoidance in Wireless Mesh Network Rahul V. Mane1, Vijaykumar V. Patil2 Department of Electronics &Tele-Communication Engineering, K.I.T’s College of Engineering, Kolhapur, Maharashtra, 416234, India 2 Asst. Prof. Department of Electronics Engineering, K.I.T’s College of Engineering, Kolhapur, Maharashtra, 416234, India ---------------------------------------------------------------------***--------------------------------------------------------------------1
Abstract - Wireless Mesh Network (WMN) have been
visualized as an important solution to the next generation wireless networking which can be used in transportation systems, home networking and last-mile wireless internet access. Modified PREQ in HWMP for Congestion Avoidance Mechanism is a proposed technique in this paper we determine congested path using CCNF frame and to provide the rerouting less congested path before congestion scenario to reduce burden on congested node. Additional approach is to continue packets transmission on congested path until it gets the rerouting path in congestion scenario. When a packet transmitted from new path the previous path will be deleted to avoid any further delay. Also sequence number is to avoid flooding in the network. We are comparing our Modified PREQ Mechanism with congestion avoidance technique to improve throughput and average delay using NS-3 Simulator. Key Words: Wireless Mesh Network, HWMP, Congestion Control, Congestion Avoidance.
1. INTRODUCTION The IEEE 802.11 standard is a wireless local area network protocol, which is largely dependent on wired infrastructure for data traffic transmission. This standard was devised to extend wired network to wireless territory. There are a series of standards under IEEE 802.11, including a, b, g etc. which are related to different wireless medium. This standard specifies frequencies, mode of communication, modulation techniques and other specification for wireless mesh networks. This standard entails two different types of networks including infrastructure mode where a definite access point is present and ad hoc mode, where no specific access point is present and two stations connect to each other on demand. IEEE 802.11s standard is an essential modification to IEEE 802.11 standard that resolves wired infrastructure dependency problem of its predecessor. This standard works in link layer of OSI model and deals with physical address of the devices rather than IP address, which can be useful in layer-2, multi hop communication. It is conceivable, and in fact quite desirable, that quality of service (QoS) guarantees can be offered to customers. If the network is designed carefully and enough Internet gateways are placed at key points, each customer can enjoy © 2016, IRJET
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guaranteed bandwidth and/or delay (at least in the access network). The guarantees enable multimedia applications such as voice over IP and video on demand. Moreover, different classes of service (e.g., premium, enhanced, and basic) can be offered, each with different priorities and guarantees. HWMP protocol provides dynamic and less congested transmission path. The main idea of implementing new protocol is to communicate devices effectively which are not in a communication area to each other i.e. hard area nodes. This algorithm provides both Reactive and Pro-active routing in the network. The reactive mode uses on demand routing i.e. Ad-hoc Distance Vector Routing Protocol. In Proactive mode uses tree based data structure which has Root node maintain routing table to keep routes to all destination. Congestion Control Mechanism apply when congestion occur in the network. This mechanism provides limit the flow of packets when congestion occurs. This comprises operations which are monitoring, detection and then controlling of congestion. Only congestion signaling part is mention in HWMP where rest of congestion control mechanism is not specified. However, various congestion control mechanism are proposed in literature to resolve this problem but anyway these methods are not sufficient to derive efficient network performance. However, congestion avoidance is better than congestion control because the latter is imposed when the network is already experiencing congestion. When the volume of queue at a specific node reaches to a pre-defined limit, it performs a buffer size check. If the queue size is near the buffer limit, the node starts broadcasting CCNF signals to its neighbors that use same path. The neighboring nodes then start searching alternative paths to send their packets to destination and avoid the path that is nearly congested as proposed in the Congestion Avoidance – HWMP (CA-HWMP). Thus, the congestion is avoided. One of the added advantage of this mechanism is that it is not only helps avoiding congestion but also helps in load balancing. Also In this paper, Modified PREQ in HWMP for Congestion Avoidance Mechanism is proposed to provide continuous transmission on a congested path until it
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