A Novel Device-to-Device Discovery Scheme for Underlay Cellular Networks

Tremendous growing demand for high data rate services such as video, gaming and social networking in wireless cellular systems, attracted researchers' attention to focus on developing proximity services. In this regard, device-to-device (D2D) communications as a promising technology for future cellular systems, plays crucial rule. The key factor in D2D communication is providing efficient peer discovery mechanisms in ultra dense networks. In this paper, we propose a centralized D2D discovery scheme by employing a signaling algorithm to exchange D2D discovery messages between network entities. In this system, potential D2D pairs share uplink cellular users' resources with collision detection, to initiate a D2D links. Stochastic geometry is used to analyze system performance in terms of success probability of the transmitted signal and minimum required time slots for the proposed discovery scheme. Extensive simulations are used to evaluate the proposed system performance.Comment: Accepted for publication in 25'th Iranian Conference on Electrical Engineering (ICEE2017

Performance Evaluation of wastewater treatment plant of Noosh Azar company by online monitoring station

Background& Objective: One of the reuses of wastewater in industries is irrigation of green space. Therefore, with proper treatment and reduction of environmental pollution of wastewater and in compliance with environmental standards, it can be used for irrigation purposes. The present study was aimed to evaluate the performance of Noosh Azar Wastewater Treatment Plant by the online monitoring station in 2016.   Materials and Methods: This descriptive cross-sectional study was performed at Noosh Azar Waste Water Treatment Plant (WWTP) in Tehran. The effluent outlet parameters include COD, BOD, TSS, TOC, Turbidity, pH and temperature which were measured 12 times/day by the online monitoring station of the refinery according to the standard methods (the Examinations of Water and Wastewater), and reported at the end of each month. Data were entered into SPSS software and analyzed using statistical indices including mean and standard deviation. Results: The average total of BOD/COD ratio in the wastewater was 0.8. The results of the study showed that the average concentration of COD, BOD and TSS of the wastewater was 1624.91 ±134.85, 1310±75.38 and 283.58± 39.76 mg/L, respectively. The average of total outlet parameters of turbidity, COD, BOD, TSS and TOC were 12.78±2.21, 83.73±12.90, 41.26±6.65, 6.70±2.14, 46.03±7.08 mg/L, and pH=7.80±0.35. The total average of removal efficiencies of COD, BOD and TSS were 93.92±3.62, 96.57±1.002 and 97.57±0.936, respectively. Conclusion: Regarding the proper performance of the activated sludge system of Noosh Azar Company, the effluent  parameters such as COD, BOD, TSS, TOC, turbidity and pH, were in accordance with the standard of the Iranian Environmental Protection Agency for irrigation use. However in order to ensure the quality of the wastewater for reuse, the microbial parameters should also be considered

Delay Analysis in Full-Duplex Heterogeneous Cellular Networks

Heterogeneous networks (HetNets) as a combination of macro cells and small cells are used to increase the cellular network's capacity, and present a perfect solution for high-speed communications. Increasing area spectrum efficiency and capacity of HetNets largely depends on the high speed of backhaul links. One effective way which is currently utilized in HetNets is the use of full-duplex (FD) technology that potentially doubles the spectral efficiency without the need for additional spectrum. On the other hand, one of the most critical network design requirements is delay, which is a key representation of the quality of service (QoS) in modern cellular networks. In this paper, by utilizing tools from the stochastic geometry, we analyze the local delay for downlink (DL) channel, which is typically defined as the mean number of required time slots for a successful communication. Given imperfect self-interference (SI) cancellation in practical FD communications, we utilize duplex mode (half-duplex (HD) or FD) for each user based on the distance from its serving base station (BS). Further, we aim to investigate the energy efficiency (EE) for both duplexing modes, i.e., HD and FD, by considering local delay. We conduct extensive simulations to validate system performance in terms of local delay versus different system key parameters.Comment: This paper has been accepted for publication in the IEEE Transactions on Vehicular Technolog