Browsing by Author "Farzamiyan, Amir Hossein"
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- A Multi-Ray Analysis of LOS V2V Links for Multiple Antennas with Ground ReflectionPublication . Farzamiyan, Amir Hossein; Gutiérrez Gaitán, Miguel; Samano-Robles, RamiroThis paper presents a vehicle-to-vehicle (V2V) geometric multi-ray tracing model for an improved line-of-sight (LOS) estimation. The model is especially suited for distributed antenna transceivers in the presence of ground reflections. The multiple antennas are assumed to be spaced regularly in horizontal and vertical directions over contiguous vehicles. The main focus of our study is the ability of the multiple antenna system to counteract or exploit, respectively, the destructive or constructive interference of multiple rays in the LOS channel component. This work is a complement to existing V2V channel models by providing more details on how ground reflections affect the LOS channel. The analysis is initially framed in the context of MIMO (multiple-input multiple-output) systems to investigate general aspects such as capacity limits and singular value distribution. The work then focuses on a scheme with single symbol repetition across the transmit antennas and two different strategies for signal combining at the receiver: maximum-ratio and equal-gain combining (MRC and EGC, respectively). These solutions are compared with a full diversity solution as well as with the information theoretical limits. An adaptive antenna selection mechanism is finally proposed that outperforms all other solutions. The paper shows both vertical and horizontal polarization results with corrected complex Fresnel reflection coefficients for lossy materials. Moreover, it is shown that multiple antenna design in V2V systems can be useful to counteract the destructive interference created by multiple rays on the LOS channel component.
- A Survey on Device-to-Device Communication in 5G Wireless NetworksPublication . Farzamiyan, Amir HosseinThe Device-to-Device (D2D) communication model in 5G networks provides a useful infrastructure to enable different applications. D2D communication, with use of cellular or ad-hoc links, improve the spectrum utilization, system throughput, and energy efficiency of the network thereby preparing the ability for the user equipment to start communications with each other in proximity. The purpose of this paper is preparing a survey based on the D2D communication and review the available literature that in a widespread way research about the D2D paradigm, different application scenarios, and use cases. Moreover, new suspicion in this area that leads to identifying open research problems of D2D communications in cellular networks.