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54. Beam position and beam hopping design for LEO satellite communications

Author

Lyu, Leyi and Qi, Chenhao

Abstract

The numbers of beam positions (BPs) and time slots for beam hopping (BH) dominate the latency of LEO satellite communications. Aiming at minimizing the number of BPs subject to a predefined requirement on the radius of BP, a low-complexity user density-based BP design scheme is proposed, where the original problem is decomposed into two subproblems, with the first one to find the sparsest user and the second one to determine the corresponding best BP. In particular, for the second subproblem, a user selection and smallest BP radius algorithm is proposed, where the nearby users are sequentially selected until the constraint of the given BP radius is no longer satisfied. These two subproblems are iteratively solved until all the users are selected. To further reduce the BP radius, a duplicated user removal algorithm is proposed to decrease the number of the users covered by two or more BPs. Aiming at minimizing the number of time slots subject to the no co-channel interference (CCI) constraint and the traffic demand constraint, a low-complexity CCI-free BH design scheme is proposed, where the BPs having difficulty in satisfying the constraints are considered to be illuminated in priory. Simulation results verify the effectiveness of the proposed schemes.

Published
2023
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87. QoS Constrained Pilot Allocation Scheme for Massive MIMO Systems.

Author

Qi, Chenhao, Sun, Xuyao, Deng, Yansha, and Nallanathan, Arumugam

Subjects
*MIMO systems, *QUALITY of service, *GREEDY algorithms, *CHANNEL estimation
Abstract

Different from the existing works, in this paper we investigate the pilot allocation in multi-cell massive multiple-input multiple-output (MIMO) systems, aiming to maximize the spectral efficiency (SE) subject to the constraint that the number of user equipments (UEs) satisfying the quality of service (QoS) is maximized. Since the considered bilevel optimization problem that is tough to handle, we resort to the greedy algorithms with low computational complexity. We propose a QoS constrained (QC) pilot allocation scheme, which sequentially allocates the pilot sequence having large interference power to the UE with small signal power so that the number of UEs satisfying QoS can be maximized and then the SE can also be maximized. Simulation results show that the propose QC scheme outperforms the conventional scheme and smart pilot allocation (SPA) scheme. [ABSTRACT FROM AUTHOR]

Published
2020
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