On the Limits of Coexisting Coverage and Capacity in Multi-RAT Multi RAT Heterogeneous Networks
Abstract: This paper devises a general modeling and analyzing framework for a heterogeneous wireless network (HetNet) in which several wireless subnetworks coexist and use multiple radio access technologies (multi-RATs). (multi RATs). The coexisting coverage and network capacity in such a multi-RAT multi RAT HetNet are hardly investigated in prior works. To characterize the coexisting interactions in a multi multi-RAT HetNet, in this paper, er, we consider a HetNet consisting of K tiers of access points (APs) and two different RATs, RAT-II and RAT-U, RAT U, are adopted in the HetNet. RAT-I RAT is adopted by the APs in the first K K-1 1 tiers and APs in the Kth tier only use RAT-U. RAT Both noncrossing-RAT and crossingRAT ossingRAT user association scenarios are considered. In each scenario, the void probability and the channel access probability of the APs in each tier are first found and then the tight lower bounds and their lowest limits on the proposed coexisting coverage coverage and network capacity are derived. We show that multi-RAT RAT networks in general can achieve higher link coverage and capacity by using opportunistic carrier sense multiple access with collision avoidance that avoids/alleviates severe interfering between all all coexisting APs. Also, crossing crossing-RAT user association is shown to achieve much higher coexisting coverage and network capacity than noncrossing noncrossing-RAT RAT user association. Finally, numerical simulations for the LTE-U U and WiFi networks coexisting in the HetNet va validate our findings.