159 research outputs found
A Novel PAPR Reduction in Filter Bank Multi-Carrier (FBMC) with Offset Quadrature Amplitude Modulation (OQAM) Based VLC Systems
The peak to average power ratio (PAPR) is one of the major problem with multicarrier-based systems. Due to its improved spectral efficiency and decreased PAPR, Filter Bank Multicarrier (FBMC) has recently become an effective alternative to the orthogonal multiplexing division (OFDM). For filter bank multicarrier communication/offset quadrature amplitude modulation-Visible light communication (FBMC/OQAM-VLC) systems is proposed a PAPR reduction technique. The suggested approach overlaps the proposed FBMC/OQAM-based VLC data signal with the existing signals. Non-redundant signals and data signals do not overlap in the frequency domain because data signals are scattered on odd subcarriers whereas built signals use even subcarriers. To reduce the effects of large-amplitude signal reduction, the suggested technique converts negative signals into positive signals rather than clipping them off as in conventional FBMC-based VLC systems. The PAPR reduction and bit error rate (BER) are realized using a scaling factor in the transformed signals. Complementary cumulative distribution function(CCDF) and BER are used to calculate the performance of the proposed approach. The presented study found that FBMC/OQAM-VLC systems to achieve a good trade-off between PAPR reduction and BER
Design guidelines for spatial modulation
A new class of low-complexity, yet energyefficient Multiple-Input Multiple-Output (MIMO) transmission techniques, namely the family of Spatial Modulation (SM) aided MIMOs (SM-MIMO) has emerged. These systems are capable of exploiting the spatial dimensions (i.e. the antenna indices) as an additional dimension invoked for transmitting information, apart from the traditional Amplitude and Phase Modulation (APM). SM is capable of efficiently operating in diverse MIMO configurations in the context of future communication systems. It constitutes a promising transmission candidate for large-scale MIMO design and for the indoor optical wireless communication whilst relying on a single-Radio Frequency (RF) chain. Moreover, SM may also be viewed as an entirely new hybrid modulation scheme, which is still in its infancy. This paper aims for providing a general survey of the SM design framework as well as of its intrinsic limits. In particular, we focus our attention on the associated transceiver design, on spatial constellation optimization, on link adaptation techniques, on distributed/ cooperative protocol design issues, and on their meritorious variants
Quantifying Potential Energy Efficiency Gain in Green Cellular Wireless Networks
Conventional cellular wireless networks were designed with the purpose of
providing high throughput for the user and high capacity for the service
provider, without any provisions of energy efficiency. As a result, these
networks have an enormous Carbon footprint. In this paper, we describe the
sources of the inefficiencies in such networks. First we present results of the
studies on how much Carbon footprint such networks generate. We also discuss
how much more mobile traffic is expected to increase so that this Carbon
footprint will even increase tremendously more. We then discuss specific
sources of inefficiency and potential sources of improvement at the physical
layer as well as at higher layers of the communication protocol hierarchy. In
particular, considering that most of the energy inefficiency in cellular
wireless networks is at the base stations, we discuss multi-tier networks and
point to the potential of exploiting mobility patterns in order to use base
station energy judiciously. We then investigate potential methods to reduce
this inefficiency and quantify their individual contributions. By a
consideration of the combination of all potential gains, we conclude that an
improvement in energy consumption in cellular wireless networks by two orders
of magnitude, or even more, is possible.Comment: arXiv admin note: text overlap with arXiv:1210.843
Analysis and Implementation of PAPR reduction algorithms for C-OFDM signals
Nowadays multicarrier modulation has become a key technology for communication systems; for example C-OFDM schemes are used in wireless LAN (802.11a/g/n), terrestrial digital television (DVB-T) and audio broadcaster (DAB) in Europe, and discrete multitone (DMT) in x.DSL systems.
The principal difficulty with OFDM is the occurrence of the coherent alignment of the time domain parallel signals at the transmitted side which forces system designer to introduce either additional hard computationally device or a suitable power back-off at the high power amplifier in order to cope with the large magnitude signal fluctuation. This leads to a significant increment in computational cost in the former case whereas in a worse allowable power utilization in the latter case with respect to the original system. However since both allowable power and computational cost are subject to a design as well as regulatory limit others solution must be accomplished. Peak reduction techniques reduce maximum-to-mean amplitude fluctuations nominating as a feasible solution. Peak-to-average power ratio is the key metric to measure this amplitude fluctuations at transmitter and to give a clear figure of merit for comparison among different techniques
PAPR reduction in FBMC using an ACE-based linear programming optimization
This paper presents four novel techniques for peak-to-average power ratio (PAPR) reduction in filter bank multicarrier
(FBMC) modulation systems. The approach extends on current PAPR reduction active constellation extension (ACE)
methods, as used in orthogonal frequency division multiplexing (OFDM), to an FBMC implementation as the main
contribution.
The four techniques introduced can be split up into two: linear programming optimization ACE-based techniques
and smart gradient-project (SGP) ACE techniques. The linear programming (LP)-based techniques compensate for
the symbol overlaps by utilizing a frame-based approach and provide a theoretical upper bound on achievable
performance for the overlapping ACE techniques. The overlapping ACE techniques on the other hand can handle
symbol by symbol processing. Furthermore, as a result of FBMC properties, the proposed techniques do not require
side information transmission. The PAPR performance of the techniques is shown to match, or in some cases improve,
on current PAPR techniques for FBMC. Initial analysis of the computational complexity of the SGP techniques indicates
that the complexity issues with PAPR reduction in FBMC implementations can be addressed.
The out-of-band interference introduced by the techniques is investigated. As a result, it is shown that the
interference can be compensated for, whilst still maintaining decent PAPR performance. Additional results are also
provided by means of a study of the PAPR reduction of the proposed techniques at a fixed clipping probability. The bit
error rate (BER) degradation is investigated to ensure that the trade-off in terms of BER degradation is not too severe.
As illustrated by exhaustive simulations, the SGP ACE-based technique proposed are ideal candidates for practical
implementation in systems employing the low-complexity polyphase implementation of FBMC modulators. The
methods are shown to offer significant PAPR reduction and increase the feasibility of FBMC as a replacement
modulation system for OFDM.http://asp.eurasipjournals.com/hb201
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