Interference coordination for LTE-advanced and FM broadcasting interoperability

The surest way to guarantee that multiple wireless systems can concurrently exist harmlessly, when operating in the same or adjacent channel, is by analyzing spectrum overlapping. This paper proposes a more accurate model to evaluate the interference power from co-channel and adjacent channel of orthogonal frequency division multiplexing-based long term evolution-advanced (LTE-Advanced) towards broadcasting frequency modulation systems at 800 MHz. Power spectral density overlapping factor is employed, and closed form of the interference power loss is derived. Numerical results demonstrate that the proposed method evaluates more exact interference power than the advanced minimum coupling loss (A-MCL) method, where the co-channel and adjacent channel interference powers are reduced by 1.3 and 3 dB, correspondingly, compared to that obtained using the AMCL method. This decreases the minimum separation distance between the two systems, which can eventually lead to efficient radio spectrum resources utilization

Interference Mitigation Using Uplink Power Control in 5G Relay-Based Heterogeneous Networks

Heterogeneous network (HetNet) is an attractive solution for future cellular networks with high data rate and coverage requirements. In HetNets, small cells such as micro cells, pico cells, femto cells and relay node (RN) are added to the network of macro cells in the same region. A large number of low power RNs produces new cell edges with significant intra-cell and inter-cell interferences. In the uplink (UL) scenarios of time-division based HetNets with RN, the user equipment (UE) desired signal may be interfered by the transmissions of the co-channel UEs during the first time slot and by the transmissions of the co-channel UEs or RNs during the second time slot. The interference caused by the RNs may significantly degrade the UE signal. UL transmission power control (PC) is essential for mitigating interference and, as a result, enhancing the cell edge and overall system performance. This research proposes a PC algorithm in order to mitigate the UL interference in 5g relay-based HetNets. This research also investigates the UL performance of HetNets when PC is applied at the RNs. Simulation results indicate that UL PC at the RNs greatly reduces average interference and improves average UL signal-to-interference-plus-noise ratio (SINR) and average UL end-to-end throughput compared to the situation in which UL PC is not implemente

Antifungal activity of chitosan against Fusarium oxysporum f. sp. cubense.

The in vitro antifungal activity of chitosan against Fusarium oxysporum f. sp. cubense Race 4 (FocR4) the causal agent of banana wilt was investigated. Chitosan at all concentrations tested reduced the hyphal growth of FocR4 on potato dextrose agar media and recording maximum inhibition of 76.36% at 8 mg/mL. The inhibitory effect was found to increase as chitosan concentration increases. The 50% effective concentration value was estimated by probit analysis, and it was 1.4 mg/mL. Chitosan was more effective in potato dextrose broth where it completely inhibited the mycelial growth of FocR4 at all concentrations tested. Chitosan inhibited the sporulation of FocR4 by a maximum of 96.53% at 8 mg/mL chitosan, and 100% inhibition for spore germination was recorded at all concentrations tested. Chitosan at concentrations of more than 1.6 mg/mL was also found to induce morphological changes in FocR4 characterized by agglomeration of hyphae, abnormal shapes, vesicles, or empty cells devoid of cytoplasm in the mycelia

Inducing host resistance against fusarium wilt of banana through application of chitosan

This study was undertaken with the aim to evaluate the effects of chitosan on the activation of defense related compounds to increase tolerance to Fusarium oxysporum f. sp. cubense Race 4 (FocR4) in susceptible banana seedlings var Berangan. In the in vitro studies, chitosan reduced the hyphal growth of FocR4 on Potato Dextrose Agar (PDA) medium and gave maximum inhibition of 76.36 % at 8 mg/ml. Inhibition of fungal growth was more efficient in Potato Dextrose Broth (PDB) where complete inhibition of mycelial growth of FocR4 was accomplished at all concentrations tested. Chitosan inhibited the sporulation of FocR4 by a maximum of 96.53 % at 8 mg/ml chitosan and 100% inhibition of spore germination was recorded at all concentrations tested. Chitosan was also found to induce morphological and cytological changes in FocR4 characterized by agglomeration of hyphae, abnormal shapes, and formation of vesicles or empty cells devoid of cytoplasm in the mycelia. Chitosan sprayed at concentrations of more than 0.3 mg/ml was found to cause damage to banana leaves. There was no significant difference in photosynthesis parameters including photosynthetic rates, stomatal conductance and chlorophyll contents within four days after spraying with chitosan at 0.3 mg/ml. However, chitosan was found to increase significantly the activities of peroxidase (PO), phenylalanine ammonia lyases (PAL), lignothioglycolic acid (LTGA), chitinases and glucanase enzymes in banana roots. The occurrence of induced resistance enhanced tolerance of the seedlings to Fusarium wilt based on parameters such as delay in onset of foliar disease symptoms, lower in percentage of disease severity (DS), lower in percentage of disease incidence (DI), area under disease progress curve (AUDPC), and epidemic rate. Vegetative growth were measured based on increased in plant height, number of leaves, diameter of pseudostem, root and shoot dry mass showing significant improvement only between treatments challenged by inoculation with FocR4 (T1 and T2). The growth of banana plants was not influenced by chitosan itself as a growth stimulator but it enhanced the growth in those infected with FocR4. The increase in PO, PAL, LTGA, chitinase and β-1,3-glucanase activity in seedlings treated with chitosan had been shown to be associated with plant defense through the decrease percentage of disease severity,disease incidence and area under disease progress curve. This indicated effective role by chitosan in controlling banana seedlings against wilt disease caused by FocR4. It showed promise as an inducer in the activation of host defense systems and increasing tolerance to FocR4 infection in susceptible banana var Berangan. Further studies regarding application frequency and combination techniques are essential to more effective of control this disease

Performance evaluation for optical backhaul and wireless front-end in hybrid optical-wireless access network

The hybrid optical-wireless access network (HOWAN) is a promising broadband access network. In this paper, the new architecture of the HOWAN is proposed and designed based on both a wavelengths division multiplexing/time division multiplexing passive optical network (WDM/TDM PON) at the optical backhaul and a wireless fidelity (WiFi) technology at the wireless front-end. The power budget of the optical backhaul based on maximum split ratio of 1/32 for each wavelength channel and a fiber length of 23 km from the central office (CO) to a 54 Mb/s access points (APs) along a 50 m outdoor wireless link is analyzed

Analysis of physical layer performance of hybrid optical-wireless access network

The hybrid optical-wireless access network (HOWAN) is a favorable architecture for next generation access network. It is an optimal combination of an optical backhaul and a wireless front-end for an efficient access network. In this paper, the HOWAN architecture is designed based on a wavelengths division multiplexing/time division multiplexing passive optical network (WDM/TDM PON) at the optical backhaul and a wireless fidelity (WiFi) technology at the wireless front-end. The HOWAN is proposed that can provide blanket coverage of broadband and flexible connection for end-users. Most of the existing works, based on performance evaluation are concerned on network layer aspects. This paper reports physical layer performance in terms of the bit error rate (BER), eye diagram, and signal-to-noise ratio (SNR) of the communication system. It accommodates 8 wavelength channels with 32 optical network unit/wireless access points (ONU/APs). It is demonstrated that downstream and upstream of 2 Gb/s can be achieved by optical backhaul for each wavelength channel along optical fiber length of 20 km and a data rate of 54 Mb/s per ONU/AP along a 50 m outdoor wireless link

Multimode interference photonic switches

Photonic switches are becoming key components in advanced optical networks due to their various applications in optical communication. One of the key advantages of photonic switches is the fact that they redirect or convert light without any optical to electronic conversions and vice versa. As one type of optical switch, multimode interference (MMI) switches have received more attention in recent years due to their significant role. The structure and operation principle of various types of MMI switches are introduced, and the recent progresses of MMI switches are also discussed

Optical power splitter based on multimode interference (MMI)

The challenge in optical access networking is to bring optical fibers as close to the end-users as possible. One way to realize this economically is to employ the passive devices. Therefore, it is necessary to use plenty of passive optical power splitters in the central office for distribution purposes. Some of the important characteristics of such splitter are low loss, compactness, and a low price. To achieve this description fully, Multimode Interference (MMI) optical power splitters based on self-imaging meet all these requirements, with considering the ability to optimize the performance of optoelectronic device over range of operational parameters. These parameters are important to reduce device length and provide increase component density. Mathematical model was used in MATLAB software and verified it by BPM-CAD to design and optimize 1X2, 1X4, 1X8, 1X16 and 1X32 power splitter based on MMI

Optimize a waveguide for thermooptic application

In this work, we present a thermal analysis of ridge and buried (conventional) single mode waveguides. The numerical simulation shows the power consumption of the present ridge waveguide is almost third of that for conventional one and the response time is half of that of the conventional one

Fabrication and characterization of polymer thermo-optic switch based on MMI coupler

The 2×2 polymer thermo-optic switch based on MMI coupler is realized. This device is fabricated using standard fabrication techniques such as coating, photolithography, and dry etching. A crosstalk level of -36.2 dB is achieved at cross and bar states. A power consumption of 1.85 mW is applied to change the state of the switch from the cross to the bar state. A switching time of less than 0.7 ms is traced to change a state of the realized switch