Intermittent Connectivity Wireless Communication Networks

Modern computer communication has been developed for providing continuous end-to-end connectivity. There are, however, communications services that are tolerant to both disruptions and transmission delay and, do not require (or cannot be given) continuous connectivity. This chapter focuses on communication over infrastructural wireless communication networks with intermittent connectivity (WCN-IC). Intermittent connectivity is due to either planned or unexpected link disruptions that may results in long delays for the communicating parties. The key assumption for WCN-IC networks is that the coverage is sparse; consequently, as long as the mobile user is in the coverage area of an information node (infocell) the user may download information to the mobile terminal storage for later usage. The communication services that may use such intermittent and high delay connections are characterized by a low degree of interactivity (i.e., broadcasting, messaging, data collection, background file downloading such as a video file, a piece of music, a weather report, etc., and background download of e-mails). In specific, two network paradigms for WCN-IC are studied in this chapter; say the spatial intermittent connectivity (SIC) and the spatial and temporal intermittent connectivity (STIC) paradigms. SIC and STIC network models are intended to operate in high traffic-density (sit-through or walk-through) and/or high mobility (drive-through) scenarios such as city centres, business districts, airports, campuses, tourist zones, and highways (Hernández-Valdez & Cruz-Pérez, 2008). Infostations (Ahmed & Miguel-Calvo, 2009; Chowdhury et al., 2010; Chowdhury et al., 2006; Frenkiel et al., 2000; Small & Haas, 2007; Small & Haas, 2003), hotspots (Doufexi et al., 2003; Goodman et al., 1997; Frenkiel & Imielinski, 1996), drive-through internet and wireless local networks-based architectures (Ott & Kutscher, 2005; Ott & Kutscher, a, 2004; Ott & Kutscher, b, 2004; Zhou et al., 2003), roadside infrastructures (Sichitiu & Kihl, 2008; Tan et al., 2009; Wu and Fijumoto, 2009), cell-hoping systems (Hassan & Jha, 2004; Hassan & Jha, 2003; Hassan & Jha, 2001), and relay stations (Pabst et al., 2004; Yanikomeroglu, 2004) are examples of SIC networks, while the Intermitstations system proposed in (HernándezValdez et al., a 2003; Hernández-Valdez et al., b 2003) is an example of a STIC network. Even though the naming varies in terms of functionalities they share the main characteristic of WCN-IC networks: the overall spatial coverage of these networks is sparse.