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In homogeneous cellular networks, fractional power control (FPC) is employed to partially compensate the path-loss and, hence, improve uplink (U L) signal-to-interference ratio (SIR). However, this scheme is less effective in heterogeneous cellular networks (HetNets) because: (i) except the typical user, all other users with variable U L transmit power (UTP) act as interferers, (ii) FPC leads to high UTP by edge users and, hence, more interference, and (iii) small base stations (SBSs)' densification further increases network interferences. Leveraging FPC in HetNets, we propose nonuniform SBS deployment (NU-SBS D) to reduce interference and, thus, increase network performance. According to our NU-SBS D model, SBS deployment (SBS D) near macro base station (MBS) is avoided, whereas MBS coverage edge area is enriched with ultra-dense SBS D. NU-SBS D model leads to: (i) better SIR reception of MBS coverage edge users, (ii) fewer SBS D requirement, and (iii) better SBS coverage in the MBS coverage edge area. Moreover, to make a model more proactive, we also consider reverse frequency allocation (RFA) to further abate both U L and downlink (D L) interferences. The coverage probability expressions are derived for both uniform SBS deployment (U-SBS D) and NU-SBS D while using RFA and FPC. Through simulation and numerical results, we characterize coverage probability for different values of SIR threshold, path loss compensation factor, SBS density, users density, and the distance between the typical user and the associated base station. The proposed NU-SBS D model along with RFA leads to reduced network interference as compared with U-SBS D and, thus, leverages FPC in HetNets.

No abstract

In heterogeneous cellular networks (HetNets), small base stations (SBSs) are overlaid in the coverage region of a macro base station (MBS) to improve coverage and spectral efficiency. However, the performance of HetNets is significantly degraded by inter-cell interference (ICI) due to aggressive frequency reuse and multi-tier deployment. Besides ICI, the uplink (UL) communications of MBS edgeusers (M-EUs) are prone to jammers' interference (JI) due to wide-band jammers (WBJs). With sufficient knowledge of network parameters, such as frequency bands and transmit powers, WBJs inject JI in the UL communications band to affect legitimate communications by degrading UL signal-to-interference ratio (SIR). Such distributed denial-of-service (DDoS) attacks normally target organizations, shopping malls, or public gatherings by clustering around them. As a countermeasure, we use decoupled association (DeCA) for the M-EUs, as opposed to the coupled association (CA), to improve UL SIR. Additionally, we use proactive interference management scheme, known as reverse frequency allocation (RFA), along with DeCA to resist both ICI and JI. The results show that WBJs cluster effectively degrades the legitimate UL communications of the target. The results also demonstrate that the network performance degrades significantly by increasing jammers' density and transmit power. Furthermore, DeCA with RFA leads to improved network performance due to effective ICI and JI mitigation. INDEX TERMS Coverage probability, denial-of-service, decoupled association, heterogeneous cellular networks, matern cluster process, poisson point process, reverse frequency allocation, wide-band jammers.

In heterogeneous wireless networks, signal-to-interference-plus-noise ratio (SINR) suffers degradation due to strong interference received by users from offloaded macro base station (mBS). Similarly, cell-edge users experience low SINR due to their distant locations. Moreover, small base stations (sBSs) located in the vicinity of mBS experience reduced coverage due to the high transmit power of mBS. To overcome these limitations, we use Stienen's model as a base station deployment strategy to improve network performance gain. More specifically, we use reverse frequency allocation (RFA) as an interference management scheme together with Stienen's model to significantly improve SINR, enhance edge user coverage, and avoid sBS deployment near the mBS. In the proposed set-up, the available coverage region is divided into two noncontiguous regions, ie, center region and outer region. Furthermore, mBSs are uniformly distributed throughout the coverage region using independent Poisson point processes, while sBSs are deployed only in outer region using Poisson hole process (PHP).Closed-form expressions for coverage probabilities are characterized for the proposed model. Numerical results show that the proposed scheme yields improved SINR with enhanced edge user coverage and requires fewer number of sBSs. KEYWORDS coverage probability, heterogeneous wireless networks, Poisson hole process, Poisson point processes, reverse frequency allocation, Stienen's model Int J Commun Syst. 2020;33:e4147.wileyonlinelibrary.com/journal/dac