Flat Cellular Networks

Current 3G systems consist of many specialized cellular access network elements that collectively form a hierarchical cellular wireless system. Instead, we argue for flat cellular systems, which need just one type of specialized network element to provide Radio Access Network (RAN) functionality, supplemented by standard IP-based network elements to form a cellular network. The reasons for building flat cellular systems are these: (1) as wireless transmission techniques evolve into Hybrid ARQ (HARQ) systems, there is less need for a hierarchical cellular system; (2) we foresee that 4G networks will be IP-based; and (3) a flat cellular system can be self scaling: there are no central components that limit the expansion of a cellular stem with newer technologies. Supporting micro- and macro-mobility in a flat cellular systems architecture is intricate, and we present our vision for mobility support based on integrated layer-2 and layer-3 mobility.