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Unformatted text preview: eterministic guarantee in the worst case, in the sense that if any of them is left out then it is not true anymore that the arising backbone is connected for any underlying flat network. Mobility-Adaptive Protocols for Managing Large Ad hoc Networks Properties of B-protocol 1. 2. 3. Each node in flat network knows only its one-hop neighbors. This induces the minimum possible overhead B-link establishment is run at each B-node only with no knowledge of the surrounding B-nodes. Again, this induces the minimum overhead Every B-node serves a number of F-nodes each of which is at most three-hops away. B-node selection protocol guarantees that all the Fnodes are served by only one neighboring B-node 4. 5. There are no two B-nodes that are neighbors in the flat network. This guarantees that B-nodes are evenly distributed in the network B-node selection is based on the node's current status (weight) Mobility-Adaptive Protocols for Managing Large Ad hoc Networks Properties of B-protocol 1. 2. The B-network is always connected provided that the underlying flat network is connected B-protocols takes into account different technologies and mechanisms that can be used to link the B-nodes in the network. Two types of Blinks are provided; namely physical and virtual links. Physical links are used when there is a direct link between B-nodes at most three hops away and virtual links are used when there is a direct link cannot be established Mobility-Adaptive Protocols for Managing Large Ad hoc Networks Simulation Environment A simulator used for an ad hoc network of nodes ranges 100 - 1000 Nodes can freely move around in a rectangular region (a grid) Node movements are discretized to grid units of 1 meter A node determines its direction randomly by choosing between its current direction (with 75% probability) and uniformly among all other directions (with 25% probability) When a node hits a grid boundary, it bounces back into the region with an angle determined by the incoming direction Fixed transmission range of each node (250 m) and the grid size have been chosen to obtain a good network connectivity Each packet contains the time-stamped, node identified weight of the sending node. All packets are sent for the one-hop neighbors only Mobility-Adaptive Protocols for Managing Large Ad hoc Networks Simulation Results k is the total number of Fnodes a B-node can serve at any point in time Three cases: k < n (where n is total number of nodes in network) k<4 k<8 Figure 1: Number of B-nodes (% w.r.t the number of the network nodes) Mobility-Adaptive Protocols for Managing Large Ad hoc Networks Simulation Results k is the total number of Fnodes a B-node can serve at any point in time Three cases: k < n (where n is total number of nodes in network) k<4 k<8 Figure 2: Number of B-links (%) when a physical link between any two B-nodes can be established directly. Mobility-Adaptive Protocols for Managing Large Ad hoc Networks Simulation Results k is the total number of Fnodes a B-node can serve at any point in time Three cases: k < n (where n is total number of nodes in network) k<4 k<8 Figure 3: Number of B-links (%) when a link between B-nodes is implemented by a physical path with at most three hops away SPAN: An Energy-Efficient Coordination Algorithm for Topology Maintenance in Ad hoc Wireless Networks [Chen+ 2002] SPAN is a power saving technique for multi-hop ad hoc networks that reduces energy consumption with the consider...
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