Routing For Partially Connected Networks In Alternately Active Mode

Ad hoc networks can be set up dynamically in places where no networking infrastructureis available, and will be widely used in the future. According to the connectivity of the networkin realistic scenarios, ad hoc networks can be classified in two groups: partially connectednetworks and fully connected networks. Most of existing ad hoc routing techniques aredesigned for fully connected networks, and will fail in partially connected networks. Researchof routing for partially connected networks focuses on communication in the cases where afully connected path between source and destination may never exist. This research isimportant for ad hoc networks to be deployed over a wide range of application classes.In many scenarios such as monitoring of coal mine or farmland, nodes seldom move andmay switch from sleeping to waking mode alternately to minimize power consumption.Sleeping of nodes may break the connectivity of networks. The networks then fall intocategory of partially connected networks, and are named partially connected networks inalternately active mode. Most of the previous work is for partially connected mobile networks,while work for partially connected networks in alternately active mode is scarce. This thesis focuses intensively on the analytical model, protocol designs and optimizationschemes for partially connected networks in alternately active mode. An analytical networkmodel for such networks is proposed. Numerical analysis is conducted on the relationshipamong sleep parameters, performance of routing protocols and energy consumption. On thebasis of network model, a new routing protocol is designed to achieve reliable routing innetworks with high sleep/wake ratio. Based on the result of numerical analysis, severalimproved schemes such as packet processing, packet scheduling and sleep scheduling areintroduced to the protocol. Simulation and theoretical analysis validate the designs. The majorachievements of the thesis are described as following:(1) Proposing a network model for partially connected networks in alternately active modeThis thesis deduces the formula of packet delivery ratio in the progress of multihop"store-wait-forward" in partially connected networks in alternately active mode. Numericalanalysis is conducted on the relationship among network parameters, power consumption andperformance of routing protocols such as packet delivery ratio and delay. A method for settingof the parameters is introduced. As an independent toolkit, this analytical model can be appliedto research on optimization of routing protocol and deployment of networks to reduce theworking load of simulation. A theoretical criterion for applicability of routing protocol isprovided in the process of ad hoc networks in power saving mode.(2) Designing a group relation routing protocol for partially connected networks in alternatelyactive modeThe thesis designs a group relation routing protocol which takes group sequence as routingmetric. This protocol can route the packets to destination in the direction specified by the groupsequence and achieve high packet delivery ratio with low probability of route failure. Thisprotocol is suitable for ad hoc networks with high sleep/wake ratio. An asynchronousforwarding scheme is designed to decrease the delay period per hop and the end-to-end delay.A remote controlling system for electric appliance is implemented over the network composedof several kinds of embedded terminals. This system can provide an accurate and reliable wayto control the electric appliance.(3) Proposing optimization schemes for the group relation routing protocolBased on the analytical model, the thesis develops schemes to enhance the performance ofthe group relation routing protocol. An algorithm is proposed to merge packets during the delayperiods in the routing progress. This algorithm can eliminate chippy packets thus minimizeenergy consumption. An evaluation of reasonable delay period is given. A probabilisticmodel-based packet scheduling scheme is introduced to increase the packet delivery ratio. Acluster-based sleep scheduling algorithm is proposed to decrease the delay period per hop andthe end-to-end delay without sacrificing the effectiveness of energy saving.