In future radio access network (RAN), many small cells (SCs) will be densely deployed to meet the capacity demand of mobile users. Centralized radio access network (CRAN) is a potential solution to increase the capacity demand of RAN. CRAN breaks the functionality of RAN between remote radio head (RRH) and baseband unit (BBU) where RRH and BBU are preferably connected by an optical link called fronthaul link. However, the deployment of fiber for fronthaul connectivity, at each SC location, is impossible or impractical due to cost or other constraints. As such, passive optical network (PON) and free-space optic (FSO) technologies have emerged as potential candidates for fronthaul transmission when the complete optical fiber-based infrastructure for fronthaul network cannot be deployed alone. We propose a hybrid PON and FSO-based method for SC fronthaul connections that considers three different network constraints, i.e., bandwidth, data rate, and latency. Based on this, we formulate the problem and propose a method to perform cell association, namely minimum sum selection (MSS). The performance is evaluated in terms of the number of SCs connected and the proposed method is compared with two other baselines, namely: minimum rate selection and random selection method. The results show that despite MSS requiring knowledge of all network constraints. It has a better performance at the cost of more computation resources, achieving gains of 7% and 6.5% in cell connections compared to the other two baseline methods.
Ultrawideband (UWB) signals have low allowable transmission powers. To enhance the coverage and capacity of UWB signals, a cost-efficient solution for the access network has been proposed and simulated. The access network is based on gamma–gamma free-space optical channel model, which is employed between the central unit and the four different carrier-free radio access units (RAUs). All-optical generation and transmission of UWB signals at a rate of 1.5 Gbps to each RAU are demonstrated. Bit error rate results are obtained to observe the performance of the UWB signals received at the mobile stations. The proposed architecture requires minimum deployment cost and gives acceptable bit error rate results.
In this paper the parametric amplification and wavelength conversion in a 1cm long silicon-on-insulator (SOI)
waveguide has been investigated numerically using coupled wave equations. The wavelength conversion efficiency is
analyzed and performance is presented with effect of pump/signal power and wavelength. The influence factors of noise
figure are also considered.
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