Peak-to-Average Power Ratio Analysis for NC-OFDM Transmissions

Rajbanshi, Rakesh; Wyglinski, Alexander M.; Minden, Gary J.

doi:10.1109/vetecf.2007.289

Cited by 30 publications

(34 citation statements)

References 11 publications

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“…There is no complementary cumulative distribution function (CCDF) expression for the PAPR of NC-OFDM system but [17] has given an upper bound on it which is p ie the maximum value of PAPR for the MPSK modulated NC-OFDM signal with p active sub-carriers is equal to p, regardless of the total number of sub-carriers.…”

Section: Papr Of Nc-ofdmmentioning

confidence: 99%

Peak to Average Power Ratio Reduction in NC–OFDM Systems

Tabassum

Hussain

Ghafoor

2015

Journal of Electrical Engineering

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Non contiguous orthogonal frequency division multiplexing (NC-OFDM) is an efficient and adaptable multicarrier modulation scheme to be used in cognitive radio communications. However like OFDM, NC-OFDM also suffers from the main drawback of high peak to average power ratio (PAPR). In this paper PAPR has been reduced by employing three different trigonometric transforms. Discrete cosine transform (DCT), discrete sine transform (DST) and fractional fourier transform (FRFT) has been combined with conventional selected level mapping (SLM) technique to reduce the PAPR of both OFDM and NC-OFDM based systems. The method combines all the transforms with SLM in different ways. Transforms DCT, DST and FRFT have been applied before the SLM block or inside the SLM block before IFFT. Simulation results show the comparative analysis of all the transforms using SLM in case of both OFDM and NC-OFDM based systems.

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Section: Papr Of Nc-ofdmmentioning

confidence: 99%

Peak to Average Power Ratio Reduction in NC–OFDM Systems

Tabassum

Hussain

Ghafoor

2015

Journal of Electrical Engineering

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“…In NC-OFDM systems, distortion-based techniques, such as clipping and filtering, and frequency-domain-based techniques assuming contiguous subcarriers, such as coding, cannot be used for reducing PAPR [6]. However, frequencydomain PAPR reduction techniques such as interleaving, SLM, and Partial Transmit Sequences (PTS) [11] are better suited, since it is easier to sort out the nulled subcarriers avoiding any interference to primary user.…”

Section: Proposed Techniquesmentioning

confidence: 99%

“…Although many techniques were introduced to reduce PAPR problem in OFDM systems, these reduction algorithms need to be carefully chosen and modified to be used for NCOFDM systems [6]. The problem of reducing PAPR occurring in cognitive radio has been studied before [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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An Efficient Adaptive Technique with Low Complexity for Reducing PAPR in OFDM-Based Cognitive Radio

Sakran

Nasr

Shokair

2012

ISRN Signal Processing

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Cognitive radio (CR) is considered nowadays as a strong candidate solution for the spectrum scarcity problem. On standards level, many cognitive radio standards have chosen Non-Contiguous Orthogonal Frequency Division Multiplexing (NC-OFDM) as their modulation scheme. Similar to OFDM, NC-OFDM suffers from the problem of having a high Peak to Average Power Ratio (PAPR). If not solved, either the transmitted signal will be distorted, which will cause interference to primary (licensed) users, or the effeciency of the power amplifier will be seriously degraded. The effect of the PAPR problem in NC-OFDM based cognitive radio networks is worse than normal OFDM systems. In this paper, we propose enhanced techniques to reduce the PAPR in NC-OFDM systems. We start by showing that combining two standard PAPR reduction techniques (interleaver-based and selective mapping) results in a lower PAPR than using them individually. Then, an "adaptive number of interleavers" will be proposed that achieves the same performance of conventional interleaver-based PAPR reduction while reducing the CPU time by 41.3%. Finally, adaptive joint interleaver with selective mapping is presented, and we show that it gives the same performance as conventional interleaver-based technique, with reduction in CPU time by a factor of 50.1%.

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“…Thus, in (4), we consider the limiting PAPR for the NC-OFDM system, P AP R max ! m Á N g , where m Á N g is the maximum possible number of active subcarriers [16]. .…”

Section: Ofdm-based Feasibility Framework For Subcarrier Allocationmentioning

confidence: 99%

OFDM-Based Common Control Channel Design for Cognitive Radio Ad Hoc Networks

Chowdhury

Akyldiz

2011

IEEE Trans. on Mobile Comput.

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Abstract-Cognitive radio (CR) technology allows devices to opportunistically use the vacant portions of the licensed wireless spectrum. However, the available spectrum changes dynamically with the primary user (PU) activity, necessitating frequent PU sensing coordination and exchanging network topology information in a multihop CR ad hoc network. To facilitate these tasks, an always-on, out-of-band common control channel (CCC) design is proposed that uses noncontiguous OFDM subcarriers placed within the guard bands separating the channels of the licensed spectrum. First, the task of choosing the OFDM-specific parameters, including the number, power, and bandwidth of the subcarriers is formulated as a feasibility problem to ensure that the CCC does not adversely interfere with the PU operation. Second, for unicast messaging between a given pair of users, a subset of the guard bands may be chosen, which allows an additional measure of protection for the adjacent PU spectrum. For this, the multiarm bandit algorithm is used that allows the guard band selection to evolve over time based on the observed interference from the PU. Results reveal that our proposed CCC ensures connectivity and improved PU protection with a limited trade-off in data rate when compared to frequencyhopping and cluster-based CCC schemes.

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Peak-to-Average Power Ratio Analysis for NC-OFDM Transmissions

Cited by 30 publications

References 11 publications

Peak to Average Power Ratio Reduction in NC–OFDM Systems

Peak to Average Power Ratio Reduction in NC–OFDM Systems

An Efficient Adaptive Technique with Low Complexity for Reducing PAPR in OFDM-Based Cognitive Radio

OFDM-Based Common Control Channel Design for Cognitive Radio Ad Hoc Networks

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