An Intelligent Pico Cell Range Expansion Technique for Heterogeneous Wireless Networks

Abstract

Background/Objectives: Due to high transmission power emitted by macro cell, very few users will be offloaded to nearby pico cell which leads to underutilization of pico cells in Heterogeneous Networks (HetNet). Method/Statistical Analysis: Cell Range Expansion (CRE) is a technique to virtually expand the coverage range of pico cell. With the help of CRE, user equipment will add a bias value to actual signal strength received from pico cell and thereby offload their traffic from macro cell to pico cell. But, at the same time adding bias value will lead to additional downlink interference which becomes severe for choosing higher bias value. Findings: Optimal bias value reduces the number of outage mobile stations but it depends on several factors which are hard to find such as the distribution of mobile stations over the cells, resource shared between pico and macro cells, mobility pattern and so on. In this paper, we are proposing a solution of Intelligent Pico Cell Range Expansion (IP-CRE) which calculates the effective bias value for each mobile station independently, by using a fuzzy logic inference system. Our proposed solution takes multiple attributes like signal strength of pico and macro cells, speed and direction of mobile stations, battery level and traffic requirements as input parameters and the output will be an effective bias value for each mobile station. We analyzed the effectiveness of the bias value by varying the number of connected Pico cell User Equipment (PUE) in the expansion region. Application/Improvements: Our observations from the simulation experiments demonstrate that the proposed scheme reduces the number of outage UE and increases the number of offloaded UE in Het Net.