Coverage, capacity and energy efficiency analysis in the uplink of mmWave cellular networks

In this paper, using the concept of stochastic geometry, we present an analytical framework to evaluate the signal-to-interference-and-noise-ratio (SINR) coverage in the uplink of millimeter wave cellular networks. By using a distance-dependent line-of-sight (LOS) probability function, the location of LOS and non-LOS users are modeled as two independent non-homogeneous Poisson point processes, with each having a different pathloss exponent. The analysis takes account of per-user fractional power control (FPC), which couples the transmission of users based on location-dependent channel inversion. We consider the following scenarios in our analysis: 1) Pathloss-based FPC (PL-FPC) which is performed using the measured pathloss and 2) Distance-based FPC (D-FPC) which is performed using the measured distance. Using the developed framework, we derive expressions for the area spectral efficiency and energy efficiency. Results suggest that in terms of SINR coverage, D-FPC outperforms PL-FPC scheme at high SINR where the future networks are expected to operate. It achieves equal or better area spectral efficiency and energy efficiency compared with the PL-FPC scheme. Contrary to the conventional ultra-high frequency cellular networks, in both FPC schemes, the SINR coverage decreases as the cell density becomes greater than a threshold, while the area spectral efficiency experiences a slow growth region

Expanding cellular coverage via cell-edge deployment in heterogeneous networks: spectral efficiency and backhaul power consumption perspectives

Heterogeneous small-cell networks (HetNets) are considered to be a standard part of future mobile networks where operator/consumer deployed small-cells, such as femtocells, relays, and distributed antennas (DAs), complement the existing macrocell infrastructure. This article proposes the need-oriented deployment of smallcells and device-to-device (D2D) communication around the edge of the macrocell such that the small-cell base stations (SBSs) and D2D communication serve the cell-edge mobile users, thereby expanding the network coverage and capacity. In this context, we present competitive network configurations, namely, femto-on-edge, DA-onedge, relay-on-edge, and D2D-communication on- edge, where femto base stations, DA elements, relay base stations, and D2D communication, respectively, are deployed around the edge of the macrocell. The proposed deployments ensure performance gains in the network in terms of spectral efficiency and power consumption by facilitating the cell-edge mobile users with small-cells and D2D communication. In order to calibrate the impact of power consumption on system performance and network topology, this article discusses the detailed breakdown of the end-to-end power consumption, which includes backhaul, access, and aggregation network power consumptions. Several comparative simulation results quantify the improvements in spectral efficiency and power consumption of the D2D-communication-onedge configuration to establish a greener network over the other competitive configurations

Spectral Efficient and Energy Aware Clustering in Cellular Networks

The current and envisaged increase of cellular traffic poses new challenges to Mobile Network Operators (MNO), who must densify their Radio Access Networks (RAN) while maintaining low Capital Expenditure and Operational Expenditure to ensure long-term sustainability. In this context, this paper analyses optimal clustering solutions based on Device-to-Device (D2D) communications to mitigate partially or completely the need for MNOs to carry out extremely dense RAN deployments. Specifically, a low complexity algorithm that enables the creation of spectral efficient clusters among users from different cells, denoted as enhanced Clustering Optimization for Resources' Efficiency (eCORE) is presented. Due to the imbalance between uplink and downlink traffic, a complementary algorithm, known as Clustering algorithm for Load Balancing (CaLB), is also proposed to create non-spectral efficient clusters when they result in a capacity increase. Finally, in order to alleviate the energy overconsumption suffered by cluster heads, the Clustering Energy Efficient algorithm (CEEa) is also designed to manage the trade-off between the capacity enhancement and the early battery drain of some users. Results show that the proposed algorithms increase the network capacity and outperform existing solutions, while, at the same time, CEEa is able to handle the cluster heads energy overconsumption

Heterogeneous cellular netwoks under diverse coupling and association criteria

Limiting the number of simultaneous active users does not affect the coverage and average symmetric binary rate but energy efficiency improves for its lower values, since the resources of the cell are distributed among less users, at the expense of an unfairer treatment as more users are kept inactive. It has been inspected that including more picocells has no worth for average rate and fairness under average criteria mainly due to the high difference of power between both tiers but energy efficiency slightly improves as more users get inactive. Cell range expansion bias reduces coverage but fairness is maximum for its mid-range values and the energy efficiency as well as the binary rate has improved much beyond those mid-range values. Finally, slight increment in fractional power control improves coverage and joint rate and provides better user fairness treatment. Our results show that for realistic path loss models, the decoupled DL/UL association does not improve the results sufficiently to compensate for the implementation difficulties it represents.Current networks are moving towards Heterogeneous Cellular Networks (HCN) arising from the combination of small cells with existing macrocells. The aim of this thesis is to analyze various performance indicators of heterogeneous cellular networks under diverse coupling and association criteria. We considered a two-tier heterogeneous cellular network with macro and pico BSs and UEs uniformly distributed. Realistic path loss models given by 3GPP have been taken into account for both macro and pico tiers. In this work, three association criteria were used to associate users to macro or a pico tier which include the coupled and decoupled association criteria. The coupled association criteria encompass nearest BS and maximum downlink average power whereas in decoupled association criteria, users were associated in DL by maximum average receive power and in UL by minimum path loss. Cell Range Expansion (CRE) and Fractional Power Control (FPC) techniques have been considered. The results showed a remarkable lack of independence and correlation between uplink and downlink coverage has been guessed even under independent Rayleigh fading. Simulation results showed that taking into account limits on the maximum spectral efficiency and on the number of simultaneous active users within a cell strongly modify the results on joint binary rate. It has been investigated that deploying a denser infrastructure by increasing the total number of BSs, not only improves coverage and average rates but also the energy efficiency and fairness