Papers Journals by Mohamed Mounir
International Journal of Sociotechnology and Knowledge Development (IJSKD), 2020
High data rate communication systems usually implement Orthogonal Frequency Division Multiplexing... more High data rate communication systems usually implement Orthogonal Frequency Division Multiplexing (OFDM) to face frequency selectivity. High Peak to Average Power Ratio (PAPR) is an OFDM disadvantage that causes Bit Error Rate (BER) degradation and out-of-band (OOB) radiation when OFDM signal pass through nonlinear Power Amplifier (PA). In order to overcome this problem larger Input Back-Off (IBO) is required. However, large IBO decreases the PA efficiency. PAPR reduction techniques are used to reduce the required IBO, so that PA efficiency is saved. Several PAPR reduction methods are introduced in literature, among them Tone Reservation based on Null Subcarriers (TRNS) is downward compatible version of Tone Reservation (TR) with small excess in the average power and low computational complexity compared to others. As will be shown, TRNS is the best practical one of the four downward compatible techniques. Performance of TRNS is controlled by three parameters; number of peak reduction tones (PRTs), predefined threshold (Amax), and number of iterations (Itr). In order to increase PAPR reduction gain, enhance BER performance, and reduce the required IBO to follow the given power spectral density (PSD), we have to choose the values of these parameters adequately. Results showed that, we have to reduce the threshold value to the average (i.e. Amax =0 dB). Also, we have to increase number of PRTs. However, we have to maintain the spectrum shape. Finally, we have to choose moderate number of iterations (e.g. Itr ≈50), as excessive increase in number of iterations is not useful, especially at high PAPR values.
Sensors , 2021
Several high-speed wireless systems use Orthogonal Frequency Division Multiplexing (OFDM) due to ... more 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
International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering, 2014
Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) is a promis... more Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) is a promising candidate for 4G broadband wireless communications. However, MIMO-OFDM inherited the problem of high Peak-to-Average Power Ratio (PAPR) from OFDM. Many PAPR reduction techniques were developed in last two decades to reduce the PAPR of OFDM, among them Partial Transmit Sequence (PTS) and Selected Mapping (SLM) show a highly successful PAPR reduction performance. In literature there are three well known approaches for extending SLM and PTS to MIMO-OFDM namely ordinary (oSLM/oPTS), simplified (sSLM/sPTS), and directed (dSLM/dPTS). Hybrid SLM-PTS techniques combine SLM and PTS in four different ways to reduce the required computational complexity lower than both SLM and PTS. Here, we will show the performance of applying ordinary and simplified approaches on the Hybrid SLM-PTS techniques in MIMO-OFDM system. Also, we will investigate the possibility of applying directed approach to Hybrid SLM-PTS techniques by means of proposed approach that combining dSLM and dPTS in one approach.
Books by Mohamed Mounir
Papers Conferences by Mohamed Mounir
IEEE 11th International Conference on Computer Engineering & Systems (ICCES), 2016
Orthogonal Frequency Division Multiplexing (OFDM) is an attractive technique for wireless communi... more 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.
IEEE, 5th Japan-Africa Conference on Electronics, Communications, and Computers (JAC-ECC), 2017
— Orthogonal Frequency Division Multiplexing (OFDM) is used in high data rate wireless applicatio... more — Orthogonal Frequency Division Multiplexing (OFDM) is used in high data rate wireless applications due to its ability to cope with frequency selectivity. However, OFDM suffers from high Peak-to-Average Power Ratio (PAPR) problem. Signals with high PAPR require Power Amplifier (PA) to work with large Input-Back-Off (IBO), which reduces the PA efficiency. On the other hand small IBO degrade BER performance and increases out-of-band (OOB) radiation. In literature, there are various PAPR reduction techniques. Among them deliberate clipping is the simplest, that has high deterministic PAPR reduction gain. In this paper, it will be shown that deliberate clipping is worsen the problem and cannot be used without Iterative Clipping Noise Cancellation (ICNC) in the receiver. On the other hand, ICNC increases the computational complexity of the receiver than that of the transmitter, so it recommended to be used in uplinks (ULs).
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Papers Journals by Mohamed Mounir
Books by Mohamed Mounir
Papers Conferences by Mohamed Mounir