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TopA Review Of Literature
Research on CLD optimization in WLANs has recently attracted significant interest in the wider networking research community (Athanasiou, Korakis, Ercetin, & Tassiulas, 2009; Caillouet, Pérennes, & Rivano, 2011; Khan, Mahmud, Loo, & Al-Raweshidy, 2008; Obeidat et al., 2012). This research is concerned with sharing information between various protocol layers, as specified in the ISO/OSI reference model (OSI Reference Model). To overcome network performance problems, the CLD framework (i.e. the integration of two or more protocol layers) has been proposed by many network researchers. For brevity only a selected set of literature that is indicative of the range of approaches used for CLD optimization to improve WLAN performance is reported in this section.
Khan et al. (2008) proposed a CLD framework for rate adaptation in 802.11 networks. This rate adaptation approach is different from the other approaches reported in the literature (Choudhury & Gibson, 2007; Lee & Chung, 2008; Xia, Jin, & Hamdi, 2007). In Khan’s solution, the rate is adapted to the changing channel state, application preferences and underlying MAC sublayer timing constraints. The design is based on a cross layer approach involving two-way (application layer with rate adaptation algorithm) communications. It also incorporates a frame loss differentiation mechanism for assessing channel variations while performing rate adaptation.
Yuan et al. (2007) proposed an opportunistic cooperative MAC (OC-MAC) protocol based on cross-layer information utilization. The idea is to determine the best relay station between source and destination based on instantaneous channel measurements. After determining the relay station, the destination station decides whether or not to use it for data transmission. OC-MAC uses relay stations for data transmission only if it can improve system performance. OC-MAC performed better (i.e. lower packet delay) than distributed coordination function (DCF).