Statistical analysis of inter-cell interference in uplink OFDMA networks with soft frequency reuse
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RESEARCH
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Statistical analysis of inter-cell interference in uplink OFDMA networks with soft frequency reuse Yuanping Zhu1,3 , Jing Xu1,2* , Jiang Wang1,2 and Yang Yang1,2
Abstract As the inter-cell interference becomes a great challenge in frequency reuse one systems, soft frequency reuse (SFR) has been widely used to deal with the severe inter-cell interference especially for cell edge users. This paper proposes an analytical method to investigate the statistics of inter-cell interference in uplink orthogonal frequency division multiple access systems when SFR scheme is adopted. Probability density functions of inter-cell interference in different frequency bands are derived and then used to deduce the expectation and variance of inter-cell interference from multiple interfering cells. The derivations are validated through numerical results. In addition, the relationship between system parameters and the statistics of inter-cell interference in different frequency bands is investigated. These contributions will give insights and guidelines for the system optimization. 1 Introduction Orthogonal frequency division multiple access (OFDMA) has been adopted in many wireless networks such as IEEE 802.16 and the 3rd Generation Partnership Project long-term evolution (LTE), due to many beneficial characteristics. Meanwhile, as the limited frequency resource becomes a bottleneck for the increasing data rate demand, it would be better to reuse the available frequency among each cell. However, inter-cell interference (ICI) will be more severe for user equipments (UEs) in the cell edge region. Many inter-cell interference coordination (ICIC) techniques have been proposed to mitigate the problem. One typical solution introduced in LTE [1] is soft frequency reuse (SFR): (1) UEs in the cell center region which experience/generate low interference and require low power to communicate with their serving evolved NodeBs (eNBs) are permitted to use the whole spectrum, and (2) UEs in the cell edge region which experience/generate strong interference and require high power to ensure reliable communication are constrained to be scheduled with *Correspondence: [email protected] 1 Key Laboratory of Wireless Sensor Network & Communication, Shanghai Institute of Microsystem Information and Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050, People’s Republic of China 2 Shanghai Research Center for Wireless Communications (WiCO), Shanghai 200335, People’s Republic of China Full list of author information is available at the end of the article
a part of the spectrum, while these resources should be allocated to UEs in the center region or not be used in neighboring cells. With such resource scheduling limitation among adjacent cells, SFR can be utilized to avoid severe ICI. Figure 1 demonstrates an example of the SFR scheme for multicell cellular networks. If statistical characteristics of ICI can be derived through theoretical analysis, time-consuming systemlevel simulations may be avoided. Therefore, res
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