In a typical 10G-Passive Optical Network (XG-PON), the propagation delay between the Optical Network Unit (ONU) and Optical Line Terminal (OLT) is about 0.3 ms. With a frame size of 125 μs, this amounts to three frames of data in the upstream and three frames of data in the downstream. Assuming no processing delays, the grants for any bandwidth requests reach the ONU after six frames in this request-grant cycle. Often, during this six-frame delay, the queue situation is changed drastically, as much, more data would arrive in the queue. As a result, the queued data that is delayed loses its significance due to its real-time nature. Unfortunately, almost all dynamic bandwidth allocation (DBA) algorithms follow this request-grant cycle and hence lacking in their performance. This paper introduces a novel approach for bandwidth allocation, called Demand Forecasting DBA (DF-DBA), which predicts ONU’s future demands by statistical modelling of the demand patterns and tends to fulfil the predicted demands just in time, which results in reduced delay. Simulation results indicate that the proposed technique out-performs previous DBAs, such as GigaPON access network (GIANT) and round robin (RR) employing the request-grant cycle in terms of Throughput and Packet delivery ratio (PDR). Circular buffers are introduced in statistical predictions, which produce the least delay for this novel DF-DBA. This paper, hence, opens up a new horizon of research in which researchers may come up with better statistical models to brew better and better results for Passive optical networks.
Summary
Visible light communication (VLC) is an alternative technology to the radio frequency (RF) for different applications in the indoor and outdoor environments, it could be utilized for illumination and communication simultaneously, and it offers several advantages over contemporary RF technologies such as low power consumption, free license, large bandwidth, and being friendly to the environment. In this paper, an indoor VLC system uniformity improvement in terms of high received power, signal‐to‐noise ratio (SNR), and bit rate, with RMS delay spread reduction, is proposed. It features a novel model that utilizes a 13‐optical attocells configuration on the ceiling. Moreover, proposed model was evaluated at different semi‐angle at half power. The average received power and SNR were improved to 2.85 dBm and 75.5 dB, while achieved received power and SNR levels at the center of the room were 4.92 dBm and 79.5 dB, respectively. A minimum average RMS delay spread of 0.4749 nanoseconds is obtained, while the highest average bit rate calculated is 211 Mb/s. The proposed model provides a better communication quality and meets illumination standards requirements.
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