International Journal of Emerging Technologies in Engineering Research (IJETER) Volume 1, Issue 1, July (2015) www.ijeter.everscience.org ISSN: 2454-6410 ©EverScience Publications 1 Inter-Cell Interference Avoidance Techniques in OFDMA based Cellular Networks: A Survey Virpartap Singh Department of Electronics and communication, Punjab Technical University, India. Gagandeep Kaur Department of Electronics and communication, Punjab Technical University, India. Abstract – Orthogonal Frequency Division Multiple Access (OFDMA) technique is extensively deployed in existing and next generation cellular networks to reduce interference and improve average network throughput. The OFDMA cellular network suffers from inter-cell interference (ICI) and the users found at the cell boundaries are more prone from ICI problem. Effective management of ICI is of paramount importance in order to improve cell edge throughput. Inter-cell interference avoidance is a method to improve the overall performance of the network. This paper surveys key issues in managing interference by using static frequency reuse techniques and provide a summary of the current developments of an efficient interference avoidance technique to reduce ICI in OFDMA based cellular networks. Index Terms – OFDMA; Frequency Reuse; Inter Cell Interference Coordination (ICIC); Long Term Evolution (LTE); LTE Advanced (LTE-A). 1. INTRODUCTION The tremendous growth of mobile user data rate necessities on multimedia applications requires ever increased system capacity and wireless spectrum. The wireless spectrum to the systems is costly and limited. Thus high system capacity or spectrum efficiency has been the main design criterion for the next generation wireless cellular networks, such as 3GPP Long-Term Evolution (LTE) and LTE Advanced (LTE-A) [1],[2]. OFDMA also referred to as multiuser-OFDM, is being considered as the multiple access method for next generation cellular networks to deliver high level of spectral efficiency over wideband channels [3]. The intra-cell interference in the network is avoided by orthogonal subcarrier allocation among users in each cell. As frequency bands are reused among different cells in a network, therefore ICI exists and the users situated at the cell boundaries are more prone to inter-cell interference due to the existence of multiple interferences from close by cells. In the downlink of emerging cellular systems such as LTE and LTE-A [1], [2], the OFDMA technology was preferred to diminish the effect of interference and to proficiently meet their high performance necessities. An OFDMA system divides the wireless spectrum into a number of channels and each channel is further divided into a number of consecutive orthogonal OFDM sub-channels [4]. Basic structure of frames in OFDMA systems is shown in fig.1. The intra-cell interference present in the system is condensed to a huge extent by the orthogonality of sub-channels. Time is divided into slots consisting of few consecutive OFDM symbols. Resource block (RB) is the smallest resource unit that can be allocated to a user. In time domain, one time slot is a single channel RB. The number of consecutive time slots forms a frame and a number of consecutive frames form a super frame. The allocation of RBs to a single user at a time is application dependent. In a given cell, each resource block is assigned utterly to one user at any time. However, the same RB can be reused by adjoining cells for different users [5]. Even with almost no intra-cell interference, ICI still present a huge challenge, caused by collision between the RBs [5]. That limits the overall system performance, in particular for the cell edge users. Figure 1: Basic Structure of Frames in OFDMA system.