INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY
VOLUME 3 ISSUE 1 –JANUARY 2015 - ISSN: 2349 - 9303
Energy Efficient Maximization in OFDM Multi-User MIMO Systems Priya.A
Abirami.T
PG Scholar M.Kumarasamy College of Engineering Department of ECE Priyaredrose24@gmail.com
Assistant Professor M.Kumarasamy College of Engineering Department of ECE abiramit.ece@mkce.ac.in
Abstract –The energy efficiency has become more important in MIMO wireless communication system in recent days.
The antennas at each end of the communications circuit are combined to minimize errors and optimize data speed. In Multiple Input Multiple Output Time Division Duplexing (MIMO TDD), by assuming reciprocity property the downlink transmission is based on uplink channel estimation. When more uplink pilot power ensures more accurate channel estimation and better downlink performance, it achieves higher energy consumption of mobile users. Link adaptation scheme uses different modulation schemes for different communication link quality. From the result of MIMO TDD, it ensures high Bit Error Rate.MIMO schemes are usually incorporated intoOFDM systems. The spatial and frequencyresource can be jointly allocated to improve EE.However, the complexity of the joint design may be prohibitive. This system is effective, in addition to that it also needs simple algorithms like energy efficiency optimization power allocation (EEOPA) algorithm of multiuser multiple input and multiple output (MU-MIMO) systems in order to obtain a trade-offbetween complexity and performance. Keywords—Energy efficiency, Link adaptation rate,multiuser MIMO (MU-MIMO), Multiple Input Multiple Output
OFDM (MIMO-OFDM), Energy Efficiency Optimization Power Allocation (EEOPA)
I.INTRODUCTION Multiple input multiple output (MIMO) wireless systems involve multiple transmit and receive antennas to increase the transmission data rate and to minimize errors. MIMO technology has attracted attention in communications, because it offers significant increases in data throughput and link range without additional bandwidth or increased transmit power. It achieves this goal by spreading the same total transmit power over the antennas to achieve an array gain that improves the spectral efficiency and to achieve a Diversity gain that improves the link reliability. In conventional wireless communications a single antenna is used at the source, and another single antenna is used at the destination. In some cases, this gives rise to problems with multipath effects. When an electromagnetic field (EM field) is met with obstructions such as hills, canyons, buildings, and utility wires, the wave fronts are scattered, and thus they take many paths to reach the destination. Usually, transmission between two antennas depends upon channel performance. Link adaptation has an important role in broadband wireless communication systems.
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It refers to the concept of adjusting transmit parameters like modulation and coding rate according channel conditions. When the channel is good, higherorder modulation and higher code rates are chosen, while when the channel is bad, less efficient lower-order modulation and lower code rates are used. Channel performance is more important Link adaptation is a technique used to improve spectrum efficiency by adapting system parameters, such as modulation scheme and coding rate, according to the channel condition. Motivated by the demand for improving the energy efficiency in mobile multimedia communication systems, various resource allocation optimization schemes aiming at enhancing energy efficiency have become one of the mainstreams in mobile multimedia communication systems, including transmission power allocation bandwidth allocation sub channel allocation etc. Multiple-input–multiple-output (MIMO) technologies can create independent parallel channels to transmit data streams, which improves spectral efficiency and system capacity without increasing the bandwidth requirement energy efficiency optimization power allocation.
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