The current chapter addresses enhanced Session Management (SM) for multiparty communications, i.e. how to setup and modify a multi-party session that may respond to context changes and adapt to satisfy the users of a service group. By using the users’ situation information, i.e. environment and network context, the chapter plans to illustrate ways to provide more accurate sessions for mobile communities. An evolved SM functional entity, aided by the network, can support the establishment of context-aware multiparty sessions in a heterogeneous environment in an efficient way. Works of the authors that have led to the current chapter include (Antoniou et al., 2009; Antoniou et al., 2009b; Antoniou et al., 2009c; Simoes et al., 2009) performed within and supported by the ICT-funded C-CAST (C-CAST, 2008) project. The chapter ends with the methodology stemming from this work representing a practical framework that can be used to investigate similar research objectives, and lists adaptations that may be achieved from this methodology.
Session Management and Multiparty Communications
In terms of group-based sessions, efficiency of session setup and session modification requires a correct definition of user groups. Nowadays, it is common to cross areas where there exists overlapping of different network access technologies, such as Wi-Fi, 3G and WiMax. The efficiency of the grouping operation (creation of a set of users to receive a given session) may depend on parameters, such as access technology, since for instance, 3G networks have lower bandwidth capabilities than Wi-Fi and WiMax networks. Thus, sub-grouping could be performed and the same service session could be delivered with different throughput (e.g., using different codings of the same content) to adapt to the current network capabilities. In addition to network traffic, other types of context should also be used to improve sub-grouping, such as noise, terminal location and speed, user’s priority and network preferences, user’s terminal capabilities, quality of received signal etc.
SM manages all the user-to-content and content-to-user relationships. In fact, it provides the necessary signalling to deliver content to its consumers, handling different types of events, specifically: session initiation, modification, termination and mobility. SM thus participates in dynamic changes, e.g. switching between different content for the same group of users because of new quality constraints. Since SM is closely interlinked with media delivery, it is responsible to ensure that content is delivered to its customer and is thus, appropriate to handle the coupling of context-awareness and multiparty communications.
There are two key issues that must be considered for achieving context-aware, adaptive multiparty communications: (a) Context-to-content matching and, (b) Session handling based on context information. We consider issue (a) to be out of scope for the current chapter, which concentrates on (b), the session enhancement. In addition, the chapter plans to address enhanced SM so that its key functionality is to motivate the creation of user subgroups, i.e. subsets of the same content group based on network, user and environment context to the extent that these are necessary for efficiency. A new session may adapt to the context of the user and the environment as well as to the context of the network. For the last adaptation, SM is aided by the network itself, which handles the selection of the best access network (when more than one access networks are available) for a particular user service request, based on dynamically collected network information.