Abstract
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 ( $\text {NU-SBS}_{\mathcal {D}} $ ) to reduce interference and, thus, increase network performance. According to our $\text {NU-SBS}_{\mathcal {D}} $ model, SBS deployment ( $\text {SBS}_{\mathcal {D}} $ ) near macro base station (MBS) is avoided, whereas MBS coverage edge area is enriched with ultra-dense $\text {SBS}_{\mathcal {D}} $ . $\text {NU-SBS}_{\mathcal {D}} $ model leads to: (i) better SIR reception of MBS coverage edge users, (ii) fewer $\text {SBS}_{\mathcal {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 ( $\text {U-SBS}_{\mathcal {D}} $ ) and $\text {NU-SBS}_{\mathcal {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 $\text {NU-SBS}_{\mathcal {D}} $ model along with RFA leads to reduced network interference as compared with $\text {U-SBS}_{\mathcal {D}} $ and, thus, leverages FPC in HetNets.
Highlights
MOTIVATION In heterogeneous cellular networks (HetNets), coverage probability, spectrum efficiency, and throughput are significantly enhanced by enriching coverage area of macro base station (MBS) with small base station deployment (SBSD) [1], [2]
Different interference management schemes have been proposed in the state-of-theart to mitigate DL and UL interferences, such as fractional frequency reuse (FFR) [15], cell range expansion (CRE) [16], soft frequency reuse (SFR) [17], and reverse frequency allocation (RFA) [18], [19]
In HetNets, fractional power control (FPC) is undesirable as it leads to significant increase in interference and, limits network performance gain
Summary
A. MOTIVATION In heterogeneous cellular networks (HetNets), coverage probability, spectrum efficiency, and throughput are significantly enhanced by enriching coverage area of macro base station (MBS) with small base station deployment (SBSD) [1], [2]. In HetNets, MBS-associated users (MBS-AUs) and SBSassociated users (SBS-AUs) share the same frequency band and, lead to high throughput. Due to the aforementioned benefits, the proposed NU-SBSD with FPC leads to efficient UL interference mitigation. Different interference management schemes have been proposed in the state-of-theart to mitigate DL and UL interferences, such as fractional frequency reuse (FFR) [15], cell range expansion (CRE) [16], soft frequency reuse (SFR) [17], and reverse frequency allocation (RFA) [18], [19]. We use NU-SBSD in conjunction with RFA and FPC to improve UL coverage performance
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