Bài giảng mạng không dây chương 7 ad hoc networks

Chương Ad-hoc Networks Agenda • Ad-hoc Networks – Introduction to MANETs (Mobile Ad Hoc Networks ) – Characteristis of MANETs – Applications – Technical challenges and issue • Media Access Control Protocols • Routing Protocols 1/19/22 – Department of Computer Introduction to MANETs (Mobile Ad Hoc Networks ) 1/19/22 – Department of Computer MANETs • • • • Consists of more than one mobile devices/nodes, connected by wireless link Connect and communicate to each others without supporting of BS Each node serves as both host and router The union forms a communication network modeled in the form of an arbitrarygraph 1/19/22 – Department of Computer MANETs • Peer-to-peer, multihop networks • Store-and-forward • As node move, the connectivity may change based on relative locations of other nodes 1/19/22 – Department of Computer MANETs • Single/Direct transmission A • B Multihop transmission A 1/19/22 C D E – Department of Computer B • Dynamic topologies Bandwidth-constrained and variable capacity links Energy-constrained operation Characteristis of MANETs Limited physical security 1/19/22 – Department of Computer • Dynamic topologies – Nodes are free to move arbitrarily – The network topology may • Change randomly • Unpredictably • Primarily consists of bidirectional links – In some cases, where the transmission power of two nodes is different, a undirectional link may exist 1/19/22 – Department of Computer • Bandwidth-constrained and variable capacity links – Wireless link  significantly lower capacity than infrastructured networks – Throughput is effected by multiple access, fading, noise, interference conditions, and so on  often much less than a radio’s maximum transmission rate – Congestion oftenly happen 1/19/22 – Department of Computer • Energy-constrained operation – Some or all of the MSs in a MANET may rely on batteries or other exhaustible means for their energy – For these nodes, the most important system design optimization criteria may be energy conservation 1/19/22 – Department of Computer 10 • AODV – Route Discovery [RREQ] 1/19/22 – Department of Computer 82 • AODV – Route Discovery [RREQ] 1/19/22 – Department of Computer 83 • AODV – Route Discovery [RREQ] 1/19/22 – Department of Computer 84 • AODV – Route Discovery [RREQ] 1/19/22 – Department of Computer 85 • AODV – Route Reply [RREP] 1/19/22 – Department of Computer 86 • AODV – Route Reply [RREP] 1/19/22 – Department of Computer 87 • AODV – Route Reply [RREP] 1/19/22 – Department of Computer 88 • AODV – Route Reply [RREP] 1/19/22 – Department of Computer 89 • AODV – Route Reply [RREP] 1/19/22 – Department of Computer 90 • AODV – Route Reply [RREP] 1/19/22 – Department of Computer 91 • Source-Initiated On-Demand Routing AODV – Summary v The AODV routing protocol is based on the DSDV algorithm v It can minimize the number of required broadcasts by creating routes on an on-demand basis v Each host maintains a routing table v Two major parts: 1/19/22 • route discovery (by flooding) • route maintenance/reply – Department of Computer 92 • Source-Initiated On-Demand AODV vs DSRRouting – DSR: Routes are discovered and cached – AODV: Next-hop info is stored 1/19/22 – Department of Computer 93 • Source-Initiated On-Demand Routing Temporally Ordered Routing Algorithm (TORA) v TORA is a source-initiated, loop-free, distributed routing algorithm based on the concept of link reversal v This protocol performs three basic functions: route creation, route maintenance, and route erasure v During the phases of creating and maintaining the route, nodes will use a "height" metric to establish a DAG (directed acyclic graph) rooted at the destination 1/19/22 – Department of Computer 94 • Source-Initiated On-Demand Routing Temporally Ordered Routing Algorithm (TORA) Route maintenance process in TORA: N N N N 1/19/22 N N N – Department of Computer 95 Hybrid Protocols • Zone Routing Protocol (ZRP) • Fisheye State Routing • Location-Aided Routing (LAR) • • Distance Routing Effect Algorithm for Mobility Relative Distance Microdiscovery Ad Hoc Routing • Power Aware Routing (PAR) • Multipath Routing Protocols – Department of Computer 1/19/22 96 ... computation: The resources in Ad- Hoc networks such as energy and network bandwidth are available in limited amounts 1/19/22 – Department of Computer 17 • In addition to that, Ad- Hoc networks inherit some...Agenda • Ad- hoc Networks – Introduction to MANETs (Mobile Ad Hoc Networks ) – Characteristis of MANETs – Applications – Technical challenges... capacity than infrastructured networks – Throughput is effected by multiple access, fading, noise, interference conditions, and so on  often much less than a radio’s maximum transmission rate