Summary
Benefits of device to device (D2D) underlying massive multi‐input multi‐output (MIMO) cellular networks are noticeable in the fifth generation (5G) of mobile broadband networks. However, the interference of such coexistence from massive MIMO and D2D, due to resource sharing between cellular users and D2D users, should be decreased. Because of this issue, the spectral efficiency of such networks will be reduced. The challenges of such networks are to control the transmit power of their users and to mitigate cellular‐to‐D2D and D2D‐to‐cellular interferences. In this paper, we introduce two techniques to enhance the performance of these systems. Since, we propose a linear receiver filter with a special structure in such coexistence network to increase intended signal and then to increase spectral efficiency. Also, in this research, to decrease the whole interference, by explaining power sets for cellular and D2D transmitter for various distance intervals, we apply an open loop power control approach in the uplink as a suboptimal solution. This solution is a closed‐form solution and is often more useful and take lower time than the optimal solution. Also, we analyze spectral efficiency for the cellular uplink of such networks with the proposed frameworks. Numerical results approve that the two proposed techniques decrease the interferences. Simulation results demonstrate an enhancement in the cellular spectral efficiency.
In this paper, a new mathematical analysis is presented that shows the effects of cyclic prefix insertion on removing inter symbol interference (ISI) and inter carrier interference (ICI) in the discrete multi-tone (DMT) systems. In the DMT, for subcarriers modulating, the input data stream is divided into lower rate sub-streams. The ISI is eliminated almost entirely by adding a guard interval (GI) at the beginning of each DMT symbol. However, rather than using an empty GI, this interval is filled with the end part of the DMT symbol. Through this method ISI and ICI are avoided. In all the previous works, the authors have shown the above results by only matrix analysis, without any information insight in different steps, but in this work we analyze it by a new method via signal processing analysis for the first time. Therefore, one knows what will be happen for every symbol in each step.
Summary
With the advent of the fifth generation of mobile radio communication by 2020, there will be many challenges such as increasing service demand with low delay in providing billions of end users called the satellite mobile users. It is expected that terrestrial communication systems will be faced with a dense network having many small cells anywhere and anytime. Therefore, there are some remote regions in the world where terrestrial systems cannot provide any services to end users. Furthermore, because of lack of spectral resources, it is very important that the spectrum is shared between satellite systems and terrestrial equipment by a suitable solution to interference management. In this paper, a heterogeneous satellite network that includes low earth orbit (LEO) satellite constellation and terrestrial equipment is proposed to provide low delay services. In this type of structure, interference management based on transmission power control between LEO satellite systems and mobile users is very important for obtaining high throughput. Moreover, in order to mitigate interference, transmission power control is shown based on noncooperative Stackelberg game under many subgames through pricing‐based algorithm and convex optimization method. Finally, the simulation results show that the performance of this study's system model will be improved through the proposed algorithm.
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