INVESTIGATING THE PERFORMANCE OF VARIOUS CHANNEL ESTIMATION TECHNIQUES FOR MIMO-OFDM SYSTEMS USING MATLAB
Woud M. Abed and Raghad K. Mohammed,College of Dentistry University of Baghdad, Iraq
This paper simulates and investigates the performance of four widely-used channel estimation techniques for MIMO-OFDM wireless communication systems; namely, super imposed pilot (SIP), comb-type, space-time block coding (STBC), and space-frequency block coding (SFBC) techniques.The performance is evaluated through a number of MATLab simulations, where the bit-error rate (BER) and the mean square error (MSE) are estimated and compared for different levels of signal-to-noise ratio (SNR). The simulation results demonstrate that the comb-type channel estimation and the SIP techniques overwhelmed the performance of the STFC and STBC techniques in terms of both bit-error rate (BER) and mean square error (MSE).
MIMO-OFDM, pilot-based channel estimation, pilot allocation, SIP, comb-type, STBC, SFBC, MATLab.
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https://wireilla.com/papers/ijmnct/V9N5/9519ijmnct01.pdf
SOLVING OPTIMAL COMPONENTS ASSIGNMENT PROBLEM FOR A MULTISTATE NETWORK USING FUZZY OPTIMIZATION
H. Hamdy1, M. R. Hassan1, M. Eid1 and M. Khalifa2, 1Aswan University, Egypt and 2South Valley University, Egypt
Optimal components assignment problem subject to system reliability, total lead-time, and total cost constraints is studied in this paper. The problem is formulated as fuzzy linear problem using fuzzy membership functions. An approach based on genetic algorithm with fuzzy optimization to sole the presented problem. The optimal solution found by the proposed approach is characterized by maximum reliability, minimum total cost and minimum total lead-time. The proposed approach is tested on different examples taken from the literature to illustrate its efficiency in comparison with other previous methods.
Components Assignment Problem, Stochastic-Flow Networks, Network Reliability, Fuzzy Multi-Objective Linear Programming, Genetic Algorithms.
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https://wireilla.com/papers/ijmnct/V9N3/9319ijmnct01.pdf
CODING SCHEMES FOR ENERGY CONSTRAINED IOTDEVICES
Mais Sami Ali and Abdulkareem Abdulrahman Kadhim Al-Nahrain University, Iraq
This paper investigates the application of advanced forward error correction techniques mainly: low-density parity checks (LDPC) code and polar code for IoT networks. These codes are under consideration for 5G systems. Different code parameters such as code rate and a number of decoding iterations are used to show their effect on the performance of the network. LDPC is performed better than polar code, over the IoT network scenario considered in the work, for the same coding rate and the number of decoding iterations. Considering bit error rate (BER) performance, LDPC with rate1/3 provided an improvement of up to 2.6 dB for additive white Gaussian noise (AWGN) channel, and 2 dB for SUI-3 (frequency selective fading channel model). LDPC code gives an improvement in throughput of about 12% as compared to polar code with a coding rate of 2/3 over AWGN channel. The corresponding values over SUI-3 channel are about 10%. Finally, in comparison with LDPC, polar code shows better energy saving for large number of decoding iterations and high coding rates.
IoT, LDPC, Polar, Energy consumption.
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https://wireilla.com/papers/ijmnct/V9N2/9219ijmnct01.pdf
EXTENDED LINEAR MULTICOMMODITY MULTI COST NETWORK AND MAXIMAL CONCURENT FLOW PROBLEMS
Ho Van Hung1 and Tran Quoc Chien2 1Quangnam University, Vietnam and 2The University of Education, University of Danang, Vietnam
Graph is a powerful mathematical tool applied in many fields as transportation, communication, informatics, economy, … In ordinary graph the weights of edges and vertexes are considered indepently where the length of a path is the sum of weights of the edges and the vertexes on this path. However, in many practical problems, weights at a vertex are not the same for all paths passing this vertex, but depend on coming and leaving edges. In the article [2], a kind of weights, called switch cost, is defined. The papers [3-6] study multicomodity flow problems in ordinary networks. The papers [3-6] study multicomodity flow problems in extended networks, where switch costs are defined for mixed graphs. The papers [12,13] develops a model of extended linear multicommodity multicost network and studies the maximal linear multicomodity multicost flow problems. The papers [14,15] study the maximal multicomodity multicost flow limited cost problems. Model of extended linear multicommodity multicost network can be applied to modelize many practical problems more exactly and effectively. The presented paper studies the maximal concurent linear multicomodity multicost flow problems, that are modelized as implicit linear programming problems. On the base of dual theory in linear programming an effective aproximate algorithms is developed.
Graph, Network, Multicommodity Multicost Flow, Optimization, Linear Programming
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https://wireilla.com/papers/ijmnct/V9N1/9119ijmnct01.pdf