Tabassum, HinaSayehvand, Javad2021-03-082021-03-082020-112021-03-08http://hdl.handle.net/10315/38155Multi-band and multi-tier heterogeneous networks have been considered as a key technology to meet the requirements of the future wireless networks; that is, 5G and beyond. In this dissertation, I studied heterogeneous cellular networks consisting of two tiers, where tier 1 is composed of small base stations (SBSs) operating on the sub-6GHz spectrum, and tier 2 consists of dense deployment of Terahertz (THz) base stations (TBSs) with lower power transmission compared to the RF layer. Using stochastic geometry (SG) tools, I modeled and analyzed the downlink performance of (i) THz-only network, and (ii) two-tier (co-existing) RF and THz network in terms of the downlink interference and coverage probability of a typical user. First, I characterized the exact LT of the aggregate interference and coverage probability of a user in a {THz-only} network. Then, for a {coexisting RF/THz network}, I derive the coverage probability of a typical user considering biased received signal power association (BRSP). In addition, asymptotic approximations are presented for scenarios where the intensity of THz BSs tends to infinity or the molecular absorption coefficient in THz approaches to zero. The proposed framework is generic to capture the performance of a typical user in various network configurations such as RF-only, THz-only, opportunistic RF/THz, and hybrid RF/THz. Finally, I extend the framework to incorporate the impact of blockages and side lobe antenna gains. The derived theoretical results are validated through extensive Monte-Carlo simulations.Author owns copyright, except where explicitly noted. Please contact the author directly with licensing requests.Electrical engineeringElectronic Thesis or Dissertation2021-03-08Terahertz (THz)InterferenceCoverage probabilityStochastic geometryPoisson point process (PPP)