Applications of ad hoc wireless networks pdf

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Quick navigation Home. Sensor networks Characteristics of sensor network Application of sensor network Lmitation of ad-hoc and sensor networks. Network: Network is series of points or nodes Interconnected by communication paths Network can interconnect with other netowrks contains subnetworks. What is Ad-hoc? Dynamic network topology The mobile nodes are free to move randomly and organize themselves arbitrarily; thus, the network's wireless topology may change rapidl and unpredictably.

Sometimes there is no coverages remote areas, ad hoc meetings, disaster areas cost can also be an argument against an infrastructure Sometimes not every station can hear every other station Data needs to be forwarded in a multihop manner. Comparisons between Cellular and Ad Hoc Wireless Networks I Cellular Networks Fixed infrastructure-based Guaranteed bandwidth designed for voice traffic Centralized routing Circuit-switched evolving toward packet switching Seamless connectivity low call drops during handoffs High cost and time of deployment Reuse of frequency spectrum through geographical channel reuse Ad Hoc Wireless Networks Infrastructureless Shared radio channel more suitable for best-effort data traffic Distributed routing Packet-switched evolving toward emulation of circuit switching Frequent path breaks due to mobility Quick and cost-effective deployment Dynamic frequency reuse based on carrier sense mechanism.

Easier to employ bandwidth reservation Bandwidth reservation requires complex medium access control protocols Comparisons between Cellular and Ad Hoc Wireless Networks II Cellular Networks Application domains include mainly civilian and commercial sectors High cost of network maintenance backup power source, staffing, etc. Mobile hosts are of relatively low complexity. Motivation Ad-hoc nodes are typically battery powered and may not support energy scavenging Node and network lifetime must be prolonged Most energy consumption is at the nodes transceiver Minimum transmit power decreases contention Higher number of simultaneous transmissions can be allowed Increase in Capacity.

Motivation Cont wireless networks have special limitations and properties such as limited bandwidth, highly dynamic topology, link interference, limited range of links, and broadcast. Characteristics and tradeoffs Characteristics Self-organized Self-deployed Decentralized Dynamic network topology.

Possibly uni-directional links Constrained resources battery power wireless transmitter range. Broadcasting Unlike wired network, every hop is broadcasting Every packet can reach every node in the radio range of the sender Flooding messages make the problem even worse Wasted bandwidth High collision rate.

The goal of a wireless sensor network is to prolong battery life at the expense of QoS and bandwidth utilization [7], whereas the objective of an ad hoc network is to provide QoS. Wireless Sensor Networks WSN New technologies have reduced the cost, size and power of micro-sensors and wireless interfaces. Environmental Monitoring Benefits from 3 technologies digital circuitry wireless communication silicon micro-machining.

Fixed infrastructure-based Guaranteed bandwidth designed for voice traffic Centralized routing Circuit-switched evolving toward packet switching Seamless connectivity low call drops during handoffs High cost and time of deployment Reuse of frequency spectrum through geographical channel reuse Easier to employ bandwidth. Open navigation menu. Close suggestions Search Search. User Settings. Skip carousel. Carousel Previous. Carousel Next. What is Scribd? Explore Ebooks. Routing techniques in wireless ad hoc networks classification and comparison Spyros Magliveras.

Download PDF. A short summary of this paper. Routing techniques in wireless ad hoc networks classification and comparison. Boca Raton, FL , U. Routing and forwarding is a core problem in networks for deliv- There have been several routing protocols proposed for wireless ering data from one node to another.

Today wireless networks are ad hoc networks. Wireless ad hoc networks are termed as protocols [1, 5, 24, 26]. Among them, three articles [1, 5, 26] mobile distributed multihop wireless networks without predeter- compare a few up to four protocols based on the simulation of mined topology preexisting fixed infrastructure or central con- the compared protocols and the authors of [24] provide a com- trol.

In this paper, we present a comprehensive review for routing prehensive survey including qualitative comparisons of nine pro- features and techniques in wireless ad hoc networks. For more tocols. Moreover, we examine more than a dozen Keywords.

Routing protocols, Wireless communications, Ad typical routing protocols, giving qualitative comparisons of their hoc networks. For example, what rout- Anywhere and Any time [22, 25].

However, wireless networks ing information is exchanged; when and how the routing infor- have special limitations and properties such as limited bandwidth, mation is exchanged, when and how routes are computed and so highly dynamic topology, link interference, limited range of links, on.

We will discuss these criteria in this section. Therefore, routing protocols for wired networks cannot be directly used in wireless networks; routing protocols for wireless networks need to be designed and implemented sep- Link state routing LSR vs. Wireless ad hoc networks formerly called packet radio and distance vector routing DVR are two underlying mecha- networks are defined as mobile distributed multihop wireless nisms for routing in wireless ad hoc networks.

In LSR [28], rout- networks [7]. In a wireless ad hoc network, there is no prede- ing information is exchanged in the form of link state packets termined topology preexisting fixed infrastructure and no cen- LSP. The LSP of a node includes link information about its tral control. The nodes in ad hoc networks communicate without neighbors. Wireless ad hoc networks are traditionally used in maintain a global network topology from the LSPs it receives, battlefield communications, law enforcement, disaster recovery and compute, by itself, routes to all other nodes.

The problem fire, earthquake, etc. Re- with LSR is that excessive routing overhead may be incurred be- cently, wireless ad hoc networks have been extensively used in cause nodes in a wireless ad hoc network move quickly and the civilian forums i.

Every node periodically ditions flooding can be reasonably robust. However, it gener- exchanges distance vectors with its neighbors. When a node re- ates an excessive amount of traffic in heavy traffic or in a large ceives distance vectors from its neighbors, it computes new routes network [15], and it is difficult to achieve flooding reliably [21] and updates its distance vector. The complete route from a source when the topology is highly dynamic. Flooding is generally used to a destination is formed, in a distributed manner, by combining to transmit control packets e.

The problems with DVR are slow convergence and the tendency of creating routing loops. Periodical update vs. Based on when the routing infor- be divided into two categories: precomputed routing and on- mation will be disseminated, we can classify routing protocols as demand routing.

Precomputed routing is also called proactive routing or table- Periodical update protocols disseminate routing information peri- driven routing [24]. In this method, the routes to all destinations odically. Periodical updates will simplify protocols and maintain are computed a priori. In order to compute routes in advance, network stability, and most importantly, enable new nodes to nodes need to store the entire or partial information about link learn about the topology and the state of the network.

However if states and network topology. In order to keep the information up the period between updates is large, the protocol may not keep the to date, nodes need to update their information periodically or information up-to-date. On the other hand, if the period is small, whenever the link state or network topology changes. The ad- too many routing packets will be disseminated which consumes vantage of precomputed routing is that when a source needs to the precious bandwidth of a wireless network.

The disadvantage is that some routes may when a link fails or a new link appears , an update packet will never be used. Another problem is that the dissemination of rout- be broadcast and the up-to-date status can be disseminated over ing information will consume a lot of the scarce wireless network the network soon. The problem might be that if the topology of bandwidth when the link state and network topology change fast networks changes rapidly, a lot of update packets will be gener- this is especially true in a wireless ad hoc network.

The conven- ated and disseminated over the network which will use a lot of tional LSR and DVR are examples of proactive routing. We will precious bandwidth, and furthermore, may cause too much fluc- use precomputed and proactive interchangeably in this paper. One solution is to use some threshold [12, 19]. On-demand routing is also called reactive routing.

In this Periodical update and event-driven update mechanisms can be method, the route to a destination may not exist in advance and used together, forming what is called a hybrid update mechanism.

When a source needs to send packets to a destination, it periodically. Moreover, whenever a node finds that a link is bro- first finds a route or several routes to the destination. This pro- ken, it distributes a message immediately. After the route s are discovered, the source transmits packets along the route s. During the trans- mission of packets, the route may be broken because the node s on the route move away or go down.

The broken route needs to Flat structure vs. The process of detecting route breakage and rebuild- ing the route is called route maintenance. The major advantage of In a flat structure, all nodes in a network are at the same level and on-demand routing is that the precious bandwidth of wireless ad have the same routing functionality. Flat routing is simple and hoc networks is greatly saved [15] because it limits the amount of efficient for small networks.

The problem is that when a network bandwidth consumed in the exchange of routing information by becomes large, the volume of routing information will be large maintaining routes to only those destinations to which the routers and it will take a long time for routing information to arrive at need to forward data traffic. On-demand routing also obviates the remote nodes. The primary used to solve the above problems [12, 15].

In hierarchical routing problem with on-demand routing is the large latency at the begin- the nodes in the network are dynamically organized into parti- ning of the transmission caused by route discovery.

We will use tions called clusters, then the clusters are aggregated again into on-demand and reactive interchangeably in this paper. Organizing a Apart from proactive route computation and reactive route dis- network into clusters help maintain a relatively stable network covery, there is another routing mechanism, called flooding [9, topology [15].