PAPR Reduction in OFDM systems

There are more than 150 pages of new material, covering
• cognitive radio (new Chapter 21);
• cooperative communications, relays, and ad hoc networks (new Chapter 22);
• video coding (new Chapter 23);
• 3GPP Long-Term Evolution (new Chapter 27);
• WiMAX (new Chapter 28).
There are furthermore significant extensions and additions on the following:
• MIMO (in Chapter 20), in particular a new section on multi-user MIMO (Section 20.3).
• IEEE 802.11n (high-throughput WiFi) in Section 29.3.
• Coding (bit-interleaved coded modulation) in Section 14.5.
• Introduction to information theory in Sections 14.1, 14.9, and Appendix 17.
• Channel models: updates of standardized channel models in Appendix 7.
• A number of minor modifications and reformulations, partly based on feedback from instructors
and readers of the book.

OFDM (Orthogonal Frequency Division Multiplexing) has been widely adopted for high data rate wireless communication systems due to its advantages such as extraordinary spectral efficiency, robustness to channel fading and better QoS (Quality of Service) performance for multiple users. However, some challenging issues are still unresolved in OFDM systems. One of the issues is the high PAPR (peak-to-average power ratio), which results in nonlinearity in power amplifiers, and causes out of band radiation and in band distortion. This paper reviews some conventional PAPR reduction techniques and their modifications to achieve better PAPR performance. Advantages and disadvantages of each technique are discussed in detail. And comparisons between different techniques are also presented. Finally, this paper makes a prospect forecast about the direction for further researches in the area of PAPR reduction for OFDM signals.

– This paper aims to present an approximate location of a Mobile Station (MS) in Microcell zone concept in GSM system based on retrieving the Timing Advance (TA) from the Base Station (BS). In microcell concept, three or more zone sites are connected to a single BS and share the same radio equipment. Therefore, a MS travels within the cell uses the same frequency band assigned to the cell and served by the zone site with the strongest signal. Unlike sectoring, this method requires no additional hardware and a handoff procedure is not required at the Mobile Station Controller (MSC) when the MS travels between different zones within the same cell. The base station switches the channel to the next zone site. This algorithm is very useful for measuring the TA by the MSC while the MS is at the idle mode, since the BS can switch the channel to a different zone. By doing so and measuring the TA at each time the channel is switched to the next zone, a promising mobile positioning technique can be determined. Matlab simulation based location results and measurements statistics are also provided as MS coordinates, distances from the zone sites and the angles between the MS position and the zone site. These results using the direct solution approximated the error in calculating the distances between the MS and the zone sites to values between 100 – 133 meters.

Orthogonal Frequency Division Multiplexing (OFDM) is taken into account to be a promising technique against the multipath attenuation channel for wireless communications. However, OFDM faces the Peak-to-Average Power magnitude relation (PAPR) downside that's a significant downside of multicarrier gear that results in power unskillfulness in RF section of the transmitter. This paper gift completely different PAPR reduction techniques ANd conclude an overall comparison of those techniques. we have a tendency to additionally simulate the chosen mapping technique (SLM) for various route range that is most effective technique for PAPR reduction once the amount of subcarrier is massive. Simulation shows that the PAPR downside reduced because the route range will increase.

Keywords: Orthogonal Frequency Division Multiplexing (OFDM), Peak-to-Average Power Ratio (PAPR), Power Amplifiers (PAs), Selected Mapping (SLM), Complementary Cumulative Distribution Function (CCDF)

this paper reviews the state of the technique of
field programmable gate array (FPGA) for partial
Reconfiguration (PR), design methodologies of Wireless
Communication System, such as Multi Carrier Code Division
Multiple Access (MC-CDMA) technique has been to be suited for
future wireless systems that are expected to provide higher data
rates and greater flexibility for the services of voice, data, video
and Internet to the users due to its property in using the
bandwidth in efficient manner. The Software Defined Radio is
considered as a wireless system applied by routines so as
software. Consequently, the use of SDR allows vehicle
manufacturers to familiarize communication applications
sustained through cars to appropriate to the standards of the
respected country presented in the object oriented programming.
FPGAs are playing a very significant role in SDR. However, in
modern wireless communication system programs, SDR and CR
need to design a wide range of waveforms complex, which it is
complicated in design and performance and implementation
needs more time. The design of the modulation and
demodulation and other signal processing application of PR
technique that have the ability to modify blocks of logic
dynamically by downloading partial bit files, while the remaining
logic is still working without interruption; thus, power
consumption and configuration time can be saved for a larger
extent. The PR using was allowed to move for fewer or smaller
devices as, decrease power and increase system upgradability.

Multiple inputs multiple output orthogonal frequency division multiplexing (MIMO-OFDM) is an attractive transmission technique for high bit-rate communication systems. MIMO-OFDM has become a promising candidate for high performance 4G broadband wireless communications. One main disadvantage of OFDM is the high peak-to-average power ratio (PAPR) of the transmitter's output signal. Selected-Mapping (SLM) scheme which does not require the transmission of side information and can reduce the peak to average power ratio (PAPR) in turbo coded orthogonal frequency division multiplexing (OFDM) system is proposed. Simulation results show that the system can achieve significant reduction in PAPR and satisfactory bit error rate performance over AWGN channels. KEYWORDS Orthogonal Frequency Division Multiplexing (OFDM), peak-to-average-power-ratio (PAPR), Selective Mapping (SLM), Complementary Cummulative Distribution Function (CCDF), Bit Error Rate (BER).

Orthogonal Frequency Division Multiplexing (OFDM) is an attractive technique for wireless communication over frequency-selective fading channels. OFDM suffers from high Peak-to-Average Power Ratio (PAPR), which limits OFDM usage and reduces the efficiency of High Power Amplifier (HPA) or badly degrades BER. Many PAPR reduction techniques have been proposed in the literature. PAPR reduction techniques can be classified into blind receiver and non-blind receiver techniques. Active Constellation Extension (ACE) is one of the best blind receiver techniques. While, Partial Transmit Sequence (PTS) can work as blind / non-blind technique. PTS has a great PAPR reduction gain on the expense of increasing computational complexity. In this paper we combine PTS with ACE in four possible ways to be suitable for blind receiver applications with better performance than conventional methods (i.e. PTS and ACE). Results show that ACE-PTS scheme is the best among others. Expectedly, any hybrid technique has computational complexity larger than that of its components. However, ACE-PTS can be used to achieve the same performance as that of PTS or worthy better, with less number of subblocks (i.e. with less computational complexity) especially in low order modulation techniques (e.g. 4-QAM and 16-QAM). Results show that ACE-PTS with V=8 can perform similar to or better than PTS with V=10 in 16-QAM or 4-QAM, respectively, with 74% and 40.5% reduction in required numbers of additions and multiplications, respectively.

OFDM (Orthogonal Frequency Division Multiplexing) has been raised a new modulation technique. Due to its advantages in multipath fading channel e.g. robust against ISI, ICI and some other advantages like best QoS for multiple users, efficient usage of bandwidth it is suggested to be the modulation technique for next generation 4G networks e.g. LTE. But along with all its advantages there are some disadvantages also e.g. High PAPR (Peak to Average Power Ratio) at the transmitter end and BER (Bit Error Rate) at the receiving end. Since OFDM is only used in the downlink of 4G networks. To reduce the problems of OFDM some techniques e.g. SLM, PTS, Clipping, Coding, & Pre-coding etc are suggested but none of them is reduce the PAPR and BER to an acceptable value. This Paper will discuss some techniques of PAPR & BER reduction, and their advantages and disadvantages in detail.

Several high-speed wireless systems use Orthogonal Frequency Division Multiplexing (OFDM) due to its advantages. 5G has adopted OFDM and is expected to be considered beyond 5G (B5G). Meanwhile, OFDM has a high Peak-to-Average Power Ratio (PAPR) problem. Hybridization between two PAPR reduction techniques gains the two techniques’ advantages. Hybrid precoding-companding techniques are attractive as they require small computational complexity to achieve high PAPR reduction gain. Many precoding-companding techniques were introduced to increasing the PAPR reduction gain. However, reducing Bit Error Rate (BER) and out-of-band (OOB) radiation are more significant than increasing PAPR reduction gain. This paper proposes a new precoding-companding technique to better reduce the BER and OOB radiation than previous precoding-companding techniques. Results showed that the proposed technique outperforms all previous precoding-companding techniques in BER enhancement and OOB radiation reduction. The proposed technique reduces the Error Vector Magnitude (EVM) by 15 dB compared with 10 dB for the best previous technique. Additionally, the proposed technique increases high power amplifier efficiency (HPA) by 11.4%, while the best previous technique increased HPA efficiency by 9.8%. Moreover, our proposal achieves PAPR reduction gain better than the most known powerful PAPR reduction technique with a 99% reduction in required computational complexity. View Full-Text

The performance of MIMO-OFDM network gets affected due to problems in the channel estimation which is essential for designing receivers. The issues in MIMO are due to sizable inadequate Cyclic Prefix (CP) in admired Orthogonal frequency division multiplexing (OFDM), a massive amount of detection error and channel estimation problem occurs due to which performance delay turn out. This paper proposes a solution, its implementation and analysis of results. The article uses the BAT and Modified Flower Pollination (MFP) algorithm for optimizing the CP length. Minimum CP length gets considered to achieve better throughput for the same MFP algorithm. This algorithm has been proposed to optimize CP length to achieve minimum error rate of bit (BER) and PAPR-Peak to average power ratio, thereby maximizing the spectrum efficiency. For comparing the efficacy of optimized CP and unoptimized CP, the paper examines the results obtained on studying the performance in the spectrum. The performance of BAT and MFP algorithm are compared with each other to determine the better optimization methodology for the problem.

—Computational complexity considers as challenging issue in conventional Partial Transmit Sequence (PTS) scheme, even though it has good performance to reduce PAPR. In this paper, one of the recently developed bio-inspired algorithm named Chicken Swarm Optimization (CSO) is implemented with the combination of Partial Transmit Sequences to reduce PAPR, one of the most featured problems in OFDM system. Results show that CSO with PTS scheme reduces the computational complexity and improves the reduction of PAPR up to 2.25 dB at 0.0011 complementary cumulative distribution function (CCDF) for an unmodified OFDM signal. Keywords-bio-inspired algorithm; CSO; partial transmit sequence; peak to average power ratio; computational complexity

Binary sequences such as chaotic-binary (CB) sequences derived from an iterative chaotic equation have
been used in selected mapping (SLM) methods to reduce the peak-to-average power ratio (PAPR) in orthogonal
frequency division multiplexing (OFDM) systems. Though CB sequences have been shown to produce good PAPR
reduction performance, their implementation requires a significant number of complex computations which may
increase both design costs and energy requirements. This paper presents an alternative form of binary sequences
derived from a Fibonacci series and referred to as Fibonacci-Binary (FB) sequences. Simulations show that although
CB sequences produce slightly improved PAPR reduction performance over the proposed FB sequences
for larger numbers of applied SLM vectors, both forms of binary sequences produce similar bit-error-rate (BER)
performance even in the presence of non-linear power amplifier distortion. In terms of computational complexity
however, it is shown that FB sequences have significantly reduced computational requirements over CB sequences
and thus may be considered as preferred option for reducing PAPR in SLM based OFDM systems.

this paper reviews the state of the technique of field programmable gate array (FPGA) for partial Reconfiguration (PR), design methodologies of Wireless Communication System, such as Multi Carrier Code Division Multiple Access (MC-CDMA) technique has been to be suited for future wireless systems that are expected to provide higher data rates and greater flexibility for the services of voice, data, video and Internet to the users due to its property in using the bandwidth in efficient manner. The Software Defined Radio is considered as a wireless system applied by routines so as software. Consequently, the use of SDR allows vehicle manufacturers to familiarize communication applications sustained through cars to appropriate to the standards of the respected country presented in the object oriented programming. FPGAs are playing a very significant role in SDR. However, in modern wireless communication system programs, SDR and CR need to design a wide range of waveforms complex, which ...

– This paper aims to present an approximate location of a Mobile Station (MS) in Microcell zone concept in GSM system based on retrieving the Timing Advance (TA) from the Base Station (BS). In microcell concept, three or more zone sites are connected to a single BS and share the same radio equipment. Therefore, a MS travels within the cell uses the same frequency band assigned to the cell and served by the zone site with the strongest signal. Unlike sectoring, this method requires no additional hardware and a handoff procedure is not required at the Mobile Station Controller (MSC) when the MS travels between different zones within the same cell. The base station switches the channel to the next zone site. This algorithm is very useful for measuring the TA by the MSC while the MS is at the idle mode, since the BS can switch the channel to a different zone. By doing so and measuring the TA at each time the channel is switched to the next zone, a promising mobile positioning technique can be determined. Matlab simulation based location results and measurements statistics are also provided as MS coordinates, distances from the zone sites and the angles between the MS position and the zone site. These results using the direct solution approximated the error in calculating the distances between the MS and the zone sites to values between 100 – 133 meters.

Orthogonal Frequency Division Multiplexing (OFDM) is one of the multicarrier modulation methodology efficiently used
for transmission of high data rate in communication system. OFDM consists of number of independent sub carrier, where
the peak value of amplitude is high, which is a cause for high Peak to Average Power Ratio (PAPR). Hence unique techniques
are proposed for PAPR reduction. Here we have proposed an innovative method by integrating the modified Partial
Transmit Sequence (PTS), Discrete Cosine Transformation (DCT) and Wavelet Packet Transform (WPT) in a single system.
The simulation results of the proposed system shows significant reduction in the PAPR performance than the ordinary PTS
technique. Using our proposed method we have attained noticeable reduction in PAPR without casing imbalance in BER
performance of the signal.

This paper addresses the issue of high computational complexity associated with side information (SI) estimation in orthogonal frequency division multiplexing (OFDM) systems that implement selected mapping (SLM) to reduce peak-to-average power ratio (PAPR). The proposed method is based on a slightly modified SLM approach that enables the use of a low complexity binary detection criterion for SI estimation, without the need for SI transmission. Simulations show that the combined PAPR reduction and BER performance of the proposed method is similar to both pilot-assisted Maximum-Likelihood (PAML) SI estimation scheme and standard SLM that presumes perfect knowledge of SI. In addition, relative to the PAML scheme, the proposed method offers significantly reduced computational complexity.

Internet of Things (IoT) is the idea to connect all devices to the internet. In IoT based devices the transmitter side should be low cost and low power. So the complexity of transmitter side should be transferred to the receiver side. Orthogonal Frequency Division Multiplexing (OFDM) is widely recognized as one of the key techniques for high data rate communications in wireless networks. The advantages of OFDM include high spectral efficiency, immunity against multipath fading and negligible inter-symbol interference. But it has a drawback of high PAPR. Among the PAPR reduction techniques clipping is selected because it is the simplest and cost-effective method. In this work, the joint estimation of clipping Amplitude and MMSE based channel estimation method has been proposed and evaluated. Here the channel is estimated by using MMSE technique and an iterative amplitude reconstruction method is used to estimate the clipping amplitude. An alternative optimization algorithm is used for the joint estimation of channel and clipping amplitude which is based on frequency domain block type training symbols. Here the channel is estimated by using LS and MMSE and made a comparison between them. The simulation results show that the MMSE has better performance than LS channel estimation in terms of SNR and MSE. The efficiency of these algorithms is evaluated by using CRLB calculation and achieves that lower bound at medium SNR. The simulation result shows a good performance without any prior information.

This paper deals with a Maximum Likelihood receiver for a nonlinearly distorted OFDM signal over a flat channel with AWGN. The nonlinearity destroys the orthogonality between subcarriers, consequently, a per subcarrier decision, used when the linear PA is considered, is no longer optimal. We propose a sub-optimal receiver based on the Maximum Likelihood (ML) criterion. The ML receiver has to find the minimum Euclidean distance between the received vector and a set of all possible OFDM symbols passed through the same nonlinearity. This approach has exponential complexity. To reduce the complexity, we propose a sub-optimal receiver that minimizes the Euclidean distance, seen as a cost function, by the gradient descent algorithm. Unfortunately, due to the nonlinearity, the cost function is non-convex. In order to overcome this obstacle, we propose a method to classify the solution, i.e., to decide if the achieved minimum is local or global. We modify the gradient descent algorithm to avoid convergence to a local minimum. It is shown that the proposed receiver outperforms the simple OFDM and iterative receivers in terms of symbol error rate (SER) performance.

In this paper, we have evaluated various methods of time-frequency-selective fading channels estimation in OFDM system and some of them improved under time varying conditions. So, these different techniques will be studied through different algorithms and for different schemes of modulations (16 QAM, BPSK, QPSK,…). Channel estimation gathers different schemes and algorithms, some of them are dedicated for slowly time
varying (such as block type arrangement insertion, Bayesian Cramer-Rao Bound, Kalman estimator, Subspace estimator,…) whereas the others concern highly time varying channels (comb type insertion,…) . There are others methods that are just suitable for stationary channels like blind or semi blind estimators. For this aim, diverse algorithms were used for these schemes such as Least Squares estimator LS, Least Minimum Squares LMS, Minimum Mean-Square-ErrorMMSE, Linear Minimum Mean-Square-Error LMMSE, Maximum Likelihood ML,…to refine estimators shown previously .