Challenges In HetNets Research Articles

Joint DL/UL Decouple User Association in Microwave and mmWave Enabled Beyond 5G Heterogeneous Networks

Beyond fifth-generation (5G) heterogeneous networks (HetNets) are facing the challenge of accommodating enormous mobile users and data traffic with scarce spectrum resources in the microWave ( $\mu $ Wave) band. In this work, we consider both challenges in HetNets comprising large size, high power base station (LHB) and relay operating in $\mu $ Wave band and small size, low power base station (SLB) and device-to-device (D2D) operating in millimeter wave (mmWave) band. We formulate user association optimization problems to pitch user association schemes based on downlink uplink decoupled (DU-DPL) access against traditional downlink uplink coupled (DU-CPL) access in HetNets to gauge the performance of these access schemes in terms of accommodating users and spectrum efficiency in $\mu $ Wave and mmWave bands. Formulated problems are non-deterministic polynomial-time hard (NP-hard) and solved using $\epsilon $ -optimal algorithm. Simulation results show the edge of DU-DPL access over DU-CPL access in terms of users association and spectrum efficiency.

Smart heterogeneous networks: a 5G paradigm

An exponential growth in data demand on wireless networks and wireless link capacity approaching its theoretical limits, bound us to find new solutions and innovative network designs to handle the enormous amount of traffic. In this paper, we discuss long term evolution-advance (LTE-A) heterogeneous networks (HetNets) being a most effective solution to break this wireless cellular capacity crunch. LTE-A HetNets provide adequate increase in capacity by utilizing multi-tier architecture consisting of different type of cells i.e macro cell, small cell, relay and device to device. However this increase in capacity comes with certain challenges in HetNets outlined in this article. Considering inter cell interference coordination (ICIC) as biggest challenge in LTE-A HetNets, this article surveys state of the art LTE-A HetNets deployments with focus on ICIC. Effective ICIC techniques allow further substantial capacity increase. We give state of the art ICIC on air-interface as well as backhaul strategies for effective ICIC in LTE-A HetNets. Operators perspective of LTE-A HetNets with some insight to future of 5G LTE-A HetNets is provided. We also provide simulation results to show how LTE-A HetNets lead to realize ambitious targets of 5G technology in terms of capacity.

Distributed Load Balancing via Message Passing for Heterogeneous Cellular Networks

This paper presents a distributed load-balancing algorithm that maximizes the network-wide sum rate in heterogeneous cellular networks (HetNets). Unlike previous studies that have considered a logarithmic utility defined with respect to the sum rate, we maximize the sum rate directly to achieve the best user association for the HetNet. To capture realistic communication scenarios, we also consider a minimum rate constraint for individual users. The corresponding problem is formulated as a combinatorial optimization of which finding the solution becomes computationally demanding as the size of the network grows. Another challenge in HetNets is that the information exchange among base stations (BSs) is limited if each tier of BSs is deployed by different network vendors or users, and this brings about the need for distributed control. To resolve these challenges, we introduce a promising approach based on a message-passing framework and derive a distributed load-balancing algorithm. The proposed algorithm developed via message passing provides a very efficient solution for the load-balancing problem with reduced computational complexity. We compare the proposed algorithm with existing load-balancing strategies. Simulation results verify that the proposed algorithm significantly improves resource utilization and mitigates the congestion of macro BSs, thereby resulting in a multifold gain to the sum rate.