Massive multiple-input multiple-output (MIMO) technology employs hundreds of antennas at the base station (BS) of a cellular system. Activating hundreds of antennas requires hundreds of radio-frequency (RF) chains tha...
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Massive multiple-input multiple-output (MIMO) technology employs hundreds of antennas at the base station (BS) of a cellular system. Activating hundreds of antennas requires hundreds of radio-frequency (RF) chains that lead to high cost and high energy consumption. Antenna selection techniques reduce the number of RF chains while curtailing the resulting performance loss. In this study, the authors consider massive-MIMO downlink with zero-forcing (ZF) precoding in a single cell. In ZF precoding with antenna selection, the number of users must always be less than or equal to the number of selected antennas, which may require adopting userselection (scheduling) algorithms. They propose a joint user and antenna selectionalgorithm to increase BS's energy efficiency (EE) and show that its performance is very close to that of the optimum exhaustive-search based scheme. Using an analytical approximation for EE of the proposed scheme in asymptotically large numbers of users region, they find the optimum number of antennas to be selected.
This study presents an analytical method that shows how spatial correlation degrades the overall performance of cooperative spectrum sensing. In a cooperative spectrum sensing, where all secondary users (SUs) report t...
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This study presents an analytical method that shows how spatial correlation degrades the overall performance of cooperative spectrum sensing. In a cooperative spectrum sensing, where all secondary users (SUs) report their sensing information to the fusion centre (FC), sensing information is correlated for closely located users due to the similar surrounding environment. Considering the soft combining at the FC, this study shows how detection performance of correlated SUs is different from uncorrelated SUs. Furthermore, an algorithm is proposed which selects best uncorrelated SUs among all SUs of the network based on received power to the FC from SUs. The simulation results confirm the performance analysis of cooperative spectrum sensing with spatial correlation on the sensing data.
In this paper, we propose a user selection algorithm for full-duplex cellular system. In full-duplex cellular system, besides self-interference (SI), the user-equipment (UE)-UE interference at downlink (DL) users is i...
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ISBN:
(纸本)9781509061969
In this paper, we propose a user selection algorithm for full-duplex cellular system. In full-duplex cellular system, besides self-interference (SI), the user-equipment (UE)-UE interference at downlink (DL) users is induced by adjacent uplink (UL) users thereby degrading the performance severely. Thus, we alleviate the UE-UE interference and improve the achievable rate of UL users at the same time by means of our proposed user selection algorithm. Specifically, we first adopt semiorthogonal userselection (SUS) algorithm [13] with ZF precoder for DL users and then we select UL users considering the trade-off between increasing the rate of UL users and decreasing the UE-UE interference. Moreover, we also propose a mode selection based on our proposed algorithm. As a result, we provide the improved achievable sum-rate of full-duplex system as guaranteeing better achievable rate for both DL and UL users, compared with those of users in half-duplex system. In addition, we analyze the complexity of the proposed user selection algorithm along with analysis of full-search algorithm. In the end, we observe that the numerical results show the improved achievable sum-rate of the proposed user selection algorithm.
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