Resource Optimization in Multi-Tier HetNets Exploiting Multi-Slope Path Loss Model

Current resource allocation techniques in cellular networks are largely based on single-slope path loss model, which falls short in accurately capturing the effect of physical environment. The phenomenon of densification makes cell patterns more irregular; therefore, the multi-slope path loss model is more realistic to approximate the increased variations in the links and interferences. In this paper, we investigate the impacts of multi-slope path loss models, where different link distances are characterized by different path loss exponents. We propose a framework for joint user association, power and subcarrier allocation on the downlink of a heterogeneous network (HetNet). The proposed scheme is formulated as a weighted sum rate maximization problem, ensuring the users' quality-of-service requirements, namely users' minimum rate, and the base stations' (BSs) maximum transmission power. We then compare the performance of the proposed approach under different path loss models with demonstrate the effectiveness of dual-slope path loss model in comparison to the single-slope path loss model. Simulation results show that the dual-slope model leads to significant improvement in network's performance in comparison to the standard single-slope model by accurately approximating the path loss exponent dependence on the link distance. Moreover, it improves the user offloading from macrocell BS to small cells by connecting the users to nearby BSs with minimal attenuation. It has been shown that the path loss exponents significantly influence the user association lying across the critical radius in the case of the dual-slope path loss model

Computationally Intelligent Techniques for Resource Management in MmWave Small Cell Networks

Ultra densification in HetNets and the advent of mmWave technology for 5G networks have led researchers to redesign the existing resource management techniques. A salient feature of this activity is to accentuate the importance of CI resource allocation schemes offering less complexity and overhead. This article overviews the existing literature on resource management in mmWave-based Het- Nets with a special emphasis on CI techniques and further proposes frameworks that ensure quality of service requirements for all network entities. More specifically, HetNets with mmWave-based small cells pose different challenges compared to an all-microwave- based system. Similarly, various modes of small cell access policies and operations of base stations in dual mode, that is, operating both mmWave and microwave links simultaneously, offer unique challenges to resource allocation. Furthermore, the use of multi-slope path loss models becomes inevitable for analysis due to irregular cell patterns and blocking characteristics of mmWave communications. This article amalgamates the unique challenges posed because of the aforementioned recent developments and proposes various CI-based techniques, including game theory and optimization routines, to perform efficient resource management

User-Centric Interference Nulling in Downlink Multi-Antenna Heterogeneous Networks

In heterogeneous networks (HetNets), strong interference due to spectrum reuse affects each user's signal-to-interference ratio (SIR), and hence is one limiting factor of network performance. In this paper, we propose a user-centric interference nulling (IN) scheme in a downlink large-scale HetNet to improve coverage/outage probability by improving each user's SIR. This IN scheme utilizes at most maximum IN degree of freedom (DoF) at each macro-BS to avoid interference to uniformly selected macro (pico) users with signal-to-individual-interference ratio (SIIR) below a macro (pico) IN threshold, where the maximum IN DoF and the two IN thresholds are three design parameters. Using tools from stochastic geometry, we first obtain a tractable expression of the coverage (equivalently outage) probability. Then, we analyze the asymptotic coverage/outage probability in the low and high SIR threshold regimes. The analytical results indicate that the maximum IN DoF can affect the order gain of the outage probability in the low SIR threshold regime, but cannot affect the order gain of the coverage probability in the high SIR threshold regime. Moreover, we characterize the optimal maximum IN DoF which optimizes the asymptotic coverage/outage probability. The optimization results reveal that the IN scheme can linearly improve the outage probability in the low SIR threshold regime, but cannot improve the coverage probability in the high SIR threshold regime. Finally, numerical results show that the proposed scheme can achieve good gains in coverage/outage probability over a maximum ratio beamforming scheme and a user-centric almost blank subframes (ABS) scheme.Comment: Transactions on Wireless Communications (under revision). arXiv admin note: text overlap with arXiv:1504.0528

A Novel Approach for Centralized 3D Radio Resource Allocation and Scheduling in Dense HetNets for 5G Control-/User-plane Separation Architectures

This paper presents a centralized 3-dimensional radio resources (namely, time, frequency, and power) allocation and scheduling approach for control-plane and user-plane (C-/U-plane) separation architectures for fifth generation mobile networks. A central station is considered where schedulers of all base stations (BSs) are located. We consider a multi-tier network that comprises of a macrocell BS (MCBS), several outdoor picocell BSs, and a number of indoor femtocell BSs (FCBSs) deployed in a number of multi-storage buildings. The system bandwidth is reused in FCBSs within each building orthogonally. In contrast to the conventional almost blank subframe, we consider a fully blank subframe based time-domain enhanced intercell interference coordination to split completely C-/U-plane traffic such that the control-plane can be served only by the MCBS and the user-plane of user equipments by their respective BSs. We propose two power management schemes for FCBSs based on whether or not the coordinated multi-point communication with joint transmission (JT CoMP) is employed during off-state of a FCBS and develop a power control mechanism for both a single user and multi-user per FCBS scenarios. An optimal value of average activation factor (OAF) for a FCBS is derived to trade-off its serving capacity and transmit power saving factor. It is shown that in order to improve the network capacity, a FCBS needs to operate at an average activation factor (AAF) greater than its OAF using JT CoMP to serve neighboring on-state FCBSs during its normal off-state, whereas at an AAF less than the OAF to improve the energy efficiency. With a system level simulation, we show that the capacity of a FCBS increases, whereas its power saving factor decreases linearly with an increase in its AAF because of serving increased traffic, and an OAF of 0.5 for the capacity scaling factor and greater than 0.5 for are found.This paper presents a centralized 3-dimensional radio resources (namely, time, frequency, and power) allocation and scheduling approach for control-plane and user-plane (C-/U-plane) separation architectures for fifth generation mobile networks. A central station is considered where schedulers of all base stations (BSs) are located. We consider a multi-tier network that comprises of a macrocell BS (MCBS), several outdoor picocell BSs, and a number of indoor femtocell BSs (FCBSs) deployed in a number of multi-storage buildings. The system bandwidth is reused in FCBSs within each building orthogonally. In contrast to the conventional almost blank subframe, we consider a fully blank subframe based time-domain enhanced intercell interference coordination to split completely C-/U-plane traffic such that the control-plane can be served only by the MCBS and the user-plane of user equipments by their respective BSs. We propose two power management schemes for FCBSs based on whether or not the coordinated multi-point communication with joint transmission (JT CoMP) is employed during off-state of a FCBS and develop a power control mechanism for both a single user and multi-user per FCBS scenarios. An optimal value of average activation factor (OAF) for a FCBS is derived to trade-off its serving capacity and transmit power saving factor. It is shown that in order to improve the network capacity, a FCBS needs to operate at an average activation factor (AAF) greater than its OAF using JT CoMP to serve neighboring on-state FCBSs during its normal off-state, whereas at an AAF less than the OAF to improve the energy efficiency. With a system level simulation, we show that the capacity of a FCBS increases, whereas its power saving factor decreases linearly with an increase in its AAF because of serving increased traffic, and an OAF of 0.5 for the capacity scaling factor k = 1/2 and greater than 0.5 for k < 1 are found.&nbsp

MM-Wave HetNet in 5G and beyond Cellular Networks Reinforcement Learning Method to improve QoS and Exploiting Path Loss Model

This paper presents High density heterogeneous networks (HetNet) which are the most promising technology for the fifth generation (5G) cellular network. Since 5G will be available for a long time, previous generation networking systems will need customization and updates. We examine the merits and drawbacks of legacy and Q-Learning (QL)-based adaptive resource allocation systems. Furthermore, various comparisons between methods and schemes are made for the purpose of evaluating the solutions for future generation. Microwave macro cells are used to enable extra high capacity such as Long-Term Evolution (LTE), eNodeB (eNB), and Multimedia Communications Wireless technology (MC), in which they are most likely to be deployed. This paper also presents four scenarios for 5G mm-Wave implementation, including proposed system architectures. The WL algorithm allocates optimal power to the small cell base station (SBS) to satisfy the minimum necessary capacity of macro cell user equipment (MUEs) and small cell user equipment (SCUEs) in order to provide quality of service (QoS) (SUEs). The challenges with dense HetNet and the massive backhaul traffic they generate are discussed in this study. Finally, a core HetNet design based on clusters is aimed at reducing backhaul traffic. According to our findings, MM-wave HetNet and MEC can be useful in a wide range of applications, including ultra-high data rate and low latency communications in 5G and beyond. We also used the channel model simulator to examine the directional power delay profile with received signal power, path loss, and path loss exponent (PLE) for both LOS and NLOS using uniform linear array (ULA) 2X2 and 64x16 antenna configurations at 38 GHz and 73 GHz mmWave bands for both LOS and NLOS (NYUSIM). The simulation results show the performance of several path loss models in the mmWave and sub-6 GHz bands. The path loss in the close-in (CI) model at mmWave bands is higher than that of open space and two ray path loss models because it considers all shadowing and reflection effects between transmitter and receiver. We also compared the suggested method to existing models like Amiri, Su, Alsobhi, Iqbal, and greedy (non adaptive), and found that it not only enhanced MUE and SUE minimum capacities and reduced BT complexity, but it also established a new minimum QoS threshold. We also talked about 6G researches in the future. When compared to utilizing the dual slope route loss model alone in a hybrid heterogeneous network, our simulation findings show that decoupling is more visible when employing the dual slope path loss model, which enhances system performance in terms of coverage and data rate