Abstract
Two major challenges for evolving LTE (Long Term Evolution) networks are to achieve enhanced system capacity and cell coverage compared with WCDMA (Wideband Code Division Multiple Access) system. Effective utilization of radio resources as well as dense spectrum reuse are at the core to attain these targets. However, dense frequency reuse may increase inter-cell interference, which in turn severely limits the capacity of users in the system. Inter-cell interference can restrict overall system performance in terms of throughput and spectral efficiency, especially for the users located at the cell edge area. Hence, careful management of inter-cell interferences becomes crucial to improve LTE system performance. In this paper, interference mitigation schemes for LTE downlink networks are investigated.
Highlights
The growing demand of providing ubiquitous broadband internet access on mobile networks has imposed the need of developing OFDMA (Orthogonal Frequency Division Multiple Access) based wireless cellular networks such as 4G networks
We mainly focus on interference avoidance schemes which are more related to the DL (Downlink) LTE networks
3.1.3 Intelligent Reuse Scheme In intelligent reuse scheme, frequency band assigned to different sectors expands depending on existing workloads. This scheme starts with a RF3 like configuration and reuse factor can be modified with the increment of workloads for becoming Partial Frequency Reuse (PFR), Soft Frequency Reuse (SFR) or RF1. 3.1.3.1 Incremental Frequency Reuse (IFR) IFR scheme was proposed to overcome some limitations of conventional SFR scheme such as low spectrum efficiency, increased co-channel interference even at low traffic load situation, overall cell capacity loss when the system is above half-full loaded
Summary
The growing demand of providing ubiquitous broadband internet access on mobile networks has imposed the need of developing OFDMA (Orthogonal Frequency Division Multiple Access) based wireless cellular networks such as 4G networks. The allocation of various resources (e.g. time/frequency/power) is controlled to increase signal to interference and noise ratio, SINR; thereby throughput, for cell edge users and to make sure ICI will be within tolerable limits [6]. When a user moves away from serving eNB and becomes closer to its adjacent eNB, the received SINR (Signal to Interference and Noise Ratio) degrades as the desired received signal power decreases and the ICI increases. A range of power and frequency allocation strategies can be adopted for cell centre and cell edge users to mitigate ICI. Considering the third situation when ICI increases (when the neighbor cells allocate the same RB to their users), various RB allocation schemes are adopted as ICI mitigation schemes in which the objective of the schemes is to reduce ICI and maintain the higher spectral efficiency concurrently It is observed from the equation (1). The conception of reserving specific portions of the bandwidth for CCU and CEU to avoid interference is named as frequency reuse technique
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