10,592 research outputs found
Max-Min Fairness Based on Cooperative-NOMA Clustering for Ultra-Reliable and Low-Latency Communications
In this paper, the performance of a cooperative relaying technique in a
non-orthogonal multiple access (NOMA) system, briefly named cooperative NOMA
(C-NOMA), is considered in short packet communications with finite blocklength
(FBL) codes. We examine the performance of a decode-and-forward (DF) relaying
along with selection combining (SC) and maximum ratio combining (MRC)
strategies at the receiver. Our goal is user clustering based on C-NOMA to
maximize fair throughput in a DL-NOMA scenario. In each cluster, the user with
a stronger channel (strong user) acts as a relay for the other one (weak user),
and optimal power and blocklength are allocated to achieve max-min throughput.Comment: 11 pages, 6 figures, This paper has been submitted for IEEE systems
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Highly Efficient Resource Allocation Techniques in 5G for NOMA-based Massive MIMO and Relaying Systems
The explosive proliferation of smart devices in the 5-th generation (5G) network expects 1,000-fold capacity enhancement, leading to the urgent need of highly resource-efficient technologies. Non-orthogonal multiple access (NOMA), a promising spectral efficient technology for 5G to serve multiple users concurrently, can be combined with massive multiple input multiple output (MIMO) and relaying technology, to achieve highly efficient communications. Hence, this thesis studies the design and resource allocation of NOMA-based massive MIMO and relaying systems.
Due to hardware constraints and channel condition variation, the first topic of the thesis develops efficient antenna selection and user scheduling algorithms for sum rate maximization in two MIMO-NOMA scenarios. In the single-band scenario, the proposed algorithm improves antenna search efficiency by limiting the candidate antennas to those are beneficial to the relevant users. In the multi-band scenario, the proposed algorithm selects the antennas and users with the highest contribution total channel gain. Numerical results show that our proposed algorithms achieve similar performance to other algorithms with reduced complexity.
The second part of the thesis proposes the relaying and power allocation scheme for the NOMA-assisted relaying system to serve multiple cell-edge users. The relay node decodes its own message from the source NOMA signal and transmits the remaining part of signal to cell-edge users. The power allocation scheme is developed by minimizing the system outage probability. To further evaluate the system performance, the ergodic capacity is approximated by analyzing the interference at cell-edge users. Numerical results proves the performance improvement of the proposed system over conventional orthogonal multiple access mechanism
Performance enhancement solutions in wireless communication networks
In this dissertation thesis, we study the new relaying protocols for different wireless network systems. We analyze and evaluate an efficiency of the transmission in terms of the outage probability over Rayleigh fading channels by mathematical analyses. The theoretical analyses are verified by performing Monte Carlo simulations.
First, we study the cooperative relaying in the Two-Way Decode-and-Forward (DF) and multi-relay DF scheme for a secondary system to obtain spectrum access along with a primary system. In particular, we proposed the Two-Way DF scheme with Energy Harvesting, and the Two-Way DF Non-orthogonal Multiple Access (NOMA) scheme with digital network coding. Besides, we also investigate the wireless systems with multi-relay; the best relay selection is presented to optimize the effect of the proposed scheme. The transmission protocols of the proposed schemes EHAF (Energy Harvesting Amplify and Forward) and EHDF (Energy Harvesting Decode and Forward) are compared together in the same environment and in term of outage probability. Hence, with the obtained results, we conclude that the proposed schemes improve the performance of the wireless cooperative relaying systems, particularly their throughput.
Second, we focus on investigating the NOMA technology and proposing the optimal solutions (protocols) to advance the data rate and to ensure the Quality of Service (QoS) for the users in the next generation of wireless communications. In this thesis, we propose a Two-Way DF NOMA scheme (called a TWNOMA protocol) in which an intermediate relay helps two source nodes to communicate with each other. Simulation and analysis results show that the proposed protocol TWNOMA is improving the data rate when comparing with a conventional Two-Way scheme using digital network coding (DNC) (called a TWDNC protocol), Two-Way scheme without using DNC (called a TWNDNC protocol) and Two-Way scheme in amplify-and-forward(AF) relay systems (called a TWANC protocol).
Finally, we considered the combination of the NOMA and physical layer security (PLS) in the Underlay Cooperative Cognitive Network (UCCN). The best relay selection strategy is investigated, which uses the NOMA and considers the PLS to enhance the transmission efficiency and secrecy of the new generation wireless networks.V tĂ©to dizertaÄnĂ prĂĄci je provedena studie novĂœch pĆenosovĂœch protokolĆŻ pro rĆŻznĂ© bezdrĂĄtovĂ© sĂĆ„ovĂ© systĂ©my. S vyuĆŸitĂm matematickĂ© analĂœzy jsme analyzovali a vyhodnotili efektivitu pĆenosu z hlediska pravdÄpodobnosti vĂœpadku pĆes RayleighĆŻv kanĂĄl. TeoretickĂ© analĂœzy jsou ovÄĆeny provedenĂœmi simulacemi metodou Monte Carlo.
Nejprve doĆĄlo ke studii kooperativnĂho pĆenosu ve dvoucestnĂ©m dekĂłduj-a-pĆedej (Two-Way Decode-and-ForwardâTWDF) a vĂcecestnĂ©m DF schĂ©matu s vÄtĆĄĂm poÄtem pĆenosovĂœch uzlĆŻ pro sekundĂĄrnĂ systĂ©m, kdy takto byl zĂskĂĄn pĆĂstup ke spektru spolu s primĂĄrnĂm systĂ©mem. KonkrĂ©tnÄ jsme navrhli dvoucestnĂ© DF schĂ©ma se zĂskĂĄvĂĄnĂm energie a dvoucestnĂ© DF neortogonĂĄlnĂ schĂ©ma s mnohonĂĄsobnĂœm pĆĂstupem (Non-orthogonal Multiple AccessâNOMA) s digitĂĄlnĂm sĂĆ„ovĂœm kĂłdovĂĄnĂm. KromÄ toho rovnÄĆŸ zkoumĂĄme bezdrĂĄtovĂ© systĂ©my s vÄtĆĄĂm poÄtem pĆenosovĂœch uzlĆŻ, kde je pĆĂtomen vĂœbÄr nejlepĆĄĂho pĆenosovĂ©ho uzlu pro optimalizaci efektivnosti navrĆŸenĂ©ho schĂ©matu. PĆenosovĂ© protokoly navrĆŸenĂœch schĂ©mat EHAF (Energy Harvesting Amplify and Forward) a EHDF(Energy Harvesting Decode and Forward) jsou spoleÄnÄ porovnĂĄny v identickĂ©m prostĆedĂ z pohledu pravdÄpodobnosti vĂœpadku. NĂĄslednÄ, na zĂĄkladÄ zĂskanĂœch vĂœsledkĆŻ, jsme dospÄli k zĂĄvÄru, ĆŸe navrĆŸenĂĄ schĂ©mata vylepĆĄujĂ vĂœkonnost bezdrĂĄtovĂœch kooperativnĂch systĂ©mĆŻ, konkrĂ©tnÄ jejich propustnost.
DĂĄle jsme se zamÄĆili na zkoumĂĄnĂ NOMA technologie a navrhli optimĂĄlnĂ ĆeĆĄenĂ (protokoly) pro urychlenĂ datovĂ©ho pĆenosu a zajiĆĄtÄnĂ QoS v dalĆĄĂ generaci bezdrĂĄtovĂœch komunikacĂ. V tĂ©to prĂĄci jsme navrhli dvoucestnĂ© DF NOMA schĂ©ma (nazĂœvĂĄno jako TWNOMA protokol), ve kterĂ©m mezilehlĂœ pĆenosovĂœ uzel napomĂĄhĂĄ dvÄma zdrojovĂœm uzlĆŻm komunikovat mezi sebou. VĂœsledky simulace a analĂœzy ukazujĂ, ĆŸe navrĆŸenĂœ protokol TWNOMA vylepĆĄuje dosaĆŸenou pĆenosovou rychlost v porovnĂĄnĂ s konvenÄnĂm dvoucestnĂœm schĂ©matem pouĆŸĂvajĂcĂm DNC (TWDNC protokol), dvoucestnĂœm schĂ©matem bez pouĆŸitĂ DNC (TWNDNC protokol) a dvoucestnĂœm schĂ©matem v zesil-a-pĆedej (amplify-and-forward) pĆenosovĂœch systĂ©mech (TWANC protokol).
Nakonec jsme zvĂĄĆŸili vyuĆŸitĂ kombinace NOMA a zabezpeÄenĂ fyzickĂ© vrstvy (Physical Layer SecurityâPLS) v podpĆŻrnĂ© kooperativnĂ kognitivnĂ sĂti (Underlay Cooperative Cognitive NetworkâUCCN). Zde je zde zkoumĂĄn vĂœbÄr nejlepĆĄĂho pĆenosovĂ©ho uzlu, kterĂœ uĆŸĂvĂĄ NOMA a bere v Ășvahu PLS pro efektivnÄjĆĄĂ pĆenos a zabezpeÄenĂ novĂ© generace bezdrĂĄtovĂœch sĂtĂ.440 - Katedra telekomunikaÄnĂ technikyvyhovÄ
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