Heterogeneous network (HetNet) is a promising cell deployment technique where low power access points are deployed overlaid on a macrocell system. It attains high throughput by intelligently reusing spectrum, and brings a trade-off between energy-and spectral-efficiency. An efficient resource allocation strategy is required to significantly improve its throughput in a bid to meet the fifth-generation (5G) high data rate requirements. In this correspondence, a new resource allocation scheme for HetNet, called multi-level soft frequency reuse for HetNet (ML-SFR HetNet), is proposed which increases the throughput several fold. In ML-SFR HetNet, mutually exclusive spectrum is allocated for macro and small cell users and well as for cell edge users among the various cells in the reuse system. We derived spectrum and power allocation expression for a generalized HetNet scenario. In addition, analytical expressions for the throughput and area spectral efficiency (ASE) are also developed. The simulations results demonstrates the efficiency of the proposed scheme which improves the throughput by around 3.5 times and outage probability reduces nearly 5 times compared to traditional SFR system.
Abstract-Due to heavy congestion in lower frequency bands, engineers are looking for new frequency bands to support new services that require higher data rates, which in turn needs broader bandwidths. To meet this requirement, extremely high frequency (EHF), particularly Q (36 to 46 GHz) and V (46 to 56 GHz) bands, is the best viable solution because of its complete availability. The most serious challenge the EHF band poses is the attenuation caused by rain. This paper investigates the effect of the rain on Q and V bands' performances in Bangladeshi climatic conditions. The rain attenuations of the two bands are predicted for the four main regions of Bangladesh using ITU rain attenuation model. The measured rain statistics is used for this prediction. It is observed that the attenuation due to rain in the Q/V band reaches up to 150 dB which is much higher than that of the currently used Ka band. The variability of the rain attenuation is also investigated over different sessions of Bangladesh. The attenuation varies from 40 dB to 170 dB depending on the months. Finally, the amount of rain fade required to compensate the high rain attenuation is also predicted for different elevation angles.
In cellular systems, maintaining data rate at the cell edge has been a challenging task due to strong co-channel interference from neighbouring cells. Several techniques have been proposed to tackle the issue, among which soft frequency reuse (SFR) is the most widely used. A novel multi-layer SFR scheme combined with cell sectoring is proposed to improve the performance in cell-edge region. Then, a spectrum allocation scheme in a three-cell reuse system is designed to ensure the maximisation of the efficiency. A generic expression for power allocation in different regions along with the signal-to-noise ratio of multi-layer SFR in sectored cell is derived. Finally, systemlevel simulation has been carried out to demonstrate the efficiency of the proposed resource allocation scheme. It is shown that the spectral efficiency at cell-edge area improves by ∼10% which is significant for the cell-edge region.
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