Design of group-oriented protocols and algorithms for wireless mobile networks
Authors: Jiannong Cao
Venue:  (2007)

In wireless mobile networks, mobile nodes normally form groups to coordinate their actions in a cooperative way. In this thesis, we develop group-oriented protocols and algorithms for two types of wireless mobile networks: mobile ad hoc network (MANET) and its Internet extension, i.e., iMANET. These protocols and algorithms together build the foundation of the research framework on group-oriented communication. We classify mobile nodes into two types based on the distribution of group members. The first type is named as the aggregated group in which all group members stay together and move following a certain group mobility model. The second type is named as the distributed group in which group members are distributed in different locations in the network and need the support of group communication using multicast forwarding. In an aggregated group, group mobility has significant effects on the design of network protocols and algorithms. In light of this, researchers have considered various issues in MANETs under the group mobility scenarios, e.g., multimedia streaming, network partition prediction, routing and data replication. We identify two properties of group mobility. The first property is the relative stability of distances between two neighboring nodes in the same group, which can be used to improve the overall system stability. Taking advantage of this property, we investigate the clustering problem in MANETs with group mobility, and propose a Stability-aware Multi-objective Clustering algorithm (SMoC). In SMoC, the relatively stable topology is constructed first, and then multi-metric clustering is conducted with the help of a multi-objective evolutionary algorithm. SMoC shows better performance than the well known Weighted Clustering Algorithm (WCA). The second property of group mobility is motion affinity, meaning that the group can be regarded as a logical subnet. Using this property, we propose GrLS, a Group-based Location Service protocol for MANETs with group mobility. In GrLS, only the group leader needs to recruit location servers and adaptively update its location to these servers while the other group nodes are exempted from these operations. Thus, the location update cost can be significantly reduced resulting in a dramatic protocol overhead reduction. In a distributed group, members normally do not coordinate their movement but often need to communicate with each other. To support group communication, we need to develop multicast routing protocols which establish and maintain efficient multicast forwarding structures, meeting certain specified quality-of-service (QoS) requirements. We develop a hybrid multicast routing protocol for MANET, referred to as the Geography-aided Multicast Zone Routing Protocol (GMZRP). GMZRP discovers a multicast forwarding tree by on-demand Multicast Route REQuest (MRREQ) propagation, which is guided by geographic information to reduce redundant transmission. For the iMANET heterogeneous network, we focus on the construction of a QoS-aware multicast tree in the backbone network and the integration of the effect caused by wireless transmission paths. We propose two algorithms, Delay and Delay Variation Multicast Algorithm (DDVMA) and the improved CBT+SP (CBT: Core- Based Tree, SP: Shortest Path) heuristic algorithm. Both algorithms can achieve better performance in terms of multicast delay variation than the existing well-known Delay and Delay Variation Constraint Algorithm (DDVCA) under the same multicast end-to-end delay constraints. Keywords: MANET; iMANET; group mobility; group communication; clustering; location service; multicast.