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1
Content available Improved Water-Filling Power Allocation for Energy-Efficient Massive MIMO Downlink Transmissions
100%
Noor Shahida M. K. , Nordin R. , Insmail M.
International Journal of Electronics and Telecommunications
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2017
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tom Vol. 63, No. 1
79--84
EN
Energy Efficiency (EE) is becoming increasingly important for wireless communications and has caught more attention due to steadily rising energy costs and environmental concerns. Recently, a new network architecture known as Massive Multiple-Input Multiple-Output (MIMO) has been proposed with the remarkable potential to achieve huge gains in EE with simple linear processing. In this paper, a power allocation algorithm is proposed for EE to achieve the optimal EE in Massive MIMO. Based on the simplified expression, we develop a new algorithm to compute the optimal power allocation algorithm and it has been compared with the existing scheme from the previous literature. An improved water filling algorithm is proposed and embedded in the power allocation algorithm to maximize EE and Spectral Efficiency (SE). The numerical analysis of the simulation results indicates an improvement of 40% in EE and 50% in SE at the downlink transmission, compared to the other existing schemes. Furthermore, the results revealed that SE does not influence the EE enhancement after using the proposed algorithm as the number of Massive MIMO antenna at the Base Station (BS) increases.
2
Content available Power Allocation for Energy-Harvesting-based Fading Cognitive Multiple Access Channels : with or without Successive Interference Cancellation
100%
Li Q. , Xu D.
International Journal of Electronics and Telecommunications
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2017
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tom Vol. 63, No. 1
65--72
EN
This paper considers a fading cognitive multiple access channel (CMAC), where multiple secondary users (SUs), who share the spectrum with a primary user (PU), transmit to a cognitive base station (CBS). A power station is assumed to harvest energy from the nature and then provide power to the SUs. We investigate the power allocation problems for such a CMAC to maximize the SU sum rate under the interference power constraint, the sum transmit power constraint and the peak transmit power constraint of each individual SU. In particular, two scenarios are considered: with successive interference cancellation (SIC) and without SIC. For the first scenario, the optimal power allocation algorithm is derived. For the second scenario, a heuristic algorithm is proposed. We show that the proposed algorithm with SIC outperforms the algorithm without SIC in terms of the SU sum rate, while the algorithm without SIC outperforms the algorithm with SIC in terms of the number of admitted SUs for a high sum transmit power limit and a low peak transmit power limit of each individual SU.
3
Content available Effect of unequal power allocation in turbo coded multi-route multi-hop networks
100%
Wada T. , Jamalipour A. , Ohuchi K. , Okada H. , Saito M.
Journal of Telecommunications and Information Technology
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2006
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tom nr 1
46-53
EN
Multi-hop ad hoc networks are promising candidates for next generation mobile communications. They have sufficient channel capacity to achieve high data rate transmission for large number of users. One advantage of multi-hop networks is to realize multi-route transmissions. Since information bit streams can be transmitted over multiple routes, we can obtain route diversity effect. In order to enhance the route diversity effect, we usually introduce forward error correction schemes. Turbo coding is one of suitable coding methods for multi-hop networks. The turbo encoder generates one message stream and two parity streams whilst the message stream is more important than the parity streams for achieving reliable communications. Thus an unequal power allocation to the message and parity streams could be effective in improving the performance. In this paper, the effect of unequal power allocation for turbo coded multi-hop networks is investigated. Assuming the channel as additive white Gaussian and binary symmetric, we will show considerable performance improvement by unequal power allocation in terms of the bit error rate performance in multi-route multi-hop networks.
4
Content available Modulation-Mode Assignment for SVD-assisted Downlink Multiuser MIMO Transmission Schemes with Iterative Detection
75%
Ahrens A. , Benavente-Peces C.
International Journal of Electronics and Telecommunications
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2011
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tom Vol. 57, No. 1
127-134
EN
Since the capacity of multiple-input multiple-output (MIMO) systems increases linearly with the minimum number of antennas at both, the transmitter as well as the receiver side, MIMO systems have attracted a lot of attention for both frequency and non-frequency selective channels and reached a state of maturity. By contrast, MIMO-aided multiple-user systems require substantial further research. In comparison to zero-forcing (ZF) multiuser transmission techniques, where all users are treated jointly, the investigated singular value decomposition (SVD) assisted DL multiuser MIMO solution takes the individual user's channel characteristics into account. In analogy to bit-interleaved coded irregular modulation, we introduce a MIMO-BICM scheme, where different user-specific signal constellations and mapping arrangement were used within a single codeword. Extrinsic information transfer (EXIT) charts are used for analyzing and optimizing the convergence behaviour of the iterative demapping and decoding. Our results show that in order to achieve the best bit-error rate, not necessarily all user-specific MIMO layers have to be activated.
5
Optimal power allocation for cognitive LTE-femtocell networks based on game theory
63%
Martyna J.
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2017
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tom nr 8-9
1067--1071, CD
EN
In this paper, a new power control scheme for cognitive LTE-femtocell networks based on game theory is proposed. The problem is formulated as a coalition graph game problem to maximise throughput and system fairness. Then, a heuristic low-complexity algorithm to solving so presented problem is given. Simulation results have validated that the proposed scheme is effective in managing the cognitive femtocell network.
PL
W tym artykule proponuje się nowy schemat kontroli mocy dla sieci kognitywnych femtokomórek LTE oparty o teorię gier. Problem jest sformułowany jako gra koalicyjna, maksymalizująca przepustowość i sprawiedliwość systemu. Następnie, przedstawiono heurystyczny algorytm o małej złożoności dla rozwiązanie tego problemu. Wyniki symulacji potwierdziły, że proponowany schemat jest efektywny dla zarządzanie femtokomórką kognitywną LTE.
6
Resource allocation in LTE-unlicensed femtocell networks
63%
Martyna J.
Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne
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2018
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tom nr 8-9
839--843, CD
EN
In this paper, resource allocation technique for LTE femtocell network in licensed and unlicensed bands is proposed. Additionally, allocation of wireless resources to each mobile user in the Wi-Fi band occurs in parallel with the bandwidth allocation between competing users in LTE. To improve the performance of femtocells, a heuristic algorithm based on Kalai-Smorodinsky solution of bargaining problem is presented. The numerical simulation conf rms the correctness of the adopted mode.
PL
W artykule zaproponowano technike przydzielania zasobów dla sieci femtokomórkowej w licencjonowanych i nielicencjonowanych pasmach. Ponadto przydzielanie zasobów bezprzewodowych każdemu użzytkownikowi mobilnemu w paśmie Wi-Fi odbywa się równolegle z alokacją szerokości pasma pomiędzy konkurującymi użytkownikami w LTE. W artykule przedstawiono heurystyczny algorytm oparty na schemacie arbitrażowym Kalai-Smorodinsky'ego dla przetargu. Symulacja numeryczna potwierdza poprawność przyjętej metody alokacji zasobów.
7
Content available OFDM for Cognitive Radio Systems: Novel Power Allocation and Bit Loading Algorithms
63%
Razmi S. , Parhizgar N.
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