Blind SNR estimation for OFDM signals in cognitive radio by Ming-qian LIU, Bing-bing LI, Ning-jie TANG, Zhao LI

“…The traditional blind SNR estimation algorithms had problems of poor performance and high computation complexity for OFDM systems in cognitive radio with low signal to noise ratio(SNR)and multi-path channel conditions,in view of which a novel blind SNR estimation method for orthogonal frequency division multiplexing(OFDM)signals was proposed.Firstly,the channel order was roughly estimated by utilizing the characteristics of autocorrelation function to determine the data interval which was free of inter-symbol interference(ISI).Secondly,the signal average power was estimated by computing the autocorrelation values of data in the determined interval.Finally,the noise average power was estimated by utilizing the characteristics that the data in cyclic prefix which was replication of part useful data.So the SNR of the received signals could be estimated.The simulation results show that the proposed method doesn’t need any prior information and has better performance and lower computation complexity,which is more suitable for OFDM systems in cognitive radio.…”
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Ulovlig påvirkningsvirksomhet i samarbeid med fremmed etterretningstjeneste by Martin Hennig

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1979 da KUTLADIĞIMIZ ÖNEMLİ OLAYLAR ve YILDÖNÜMLERİ by Necmeddin Sefercioğlu

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OFDM transmission scheme with subcarrier supply index modulation by Yi GUO, Yiqing WANG, Yuanyuan FAN, Gang LIU

“…To address the drawback that subcarrier activation pattern (SAP) of the orthogonal frequency division multiplexing with index modulation (OFDM-IM) cannot match the binary numbers which affects the system performance, the orthogonal frequency division multiplexing with subcarrier supply index modulation (OFDM-SSIM) transmission scheme was proposed.The index utilization of the system was improved and the spectral efficiency (SE) of the system was enhanced by adding the supply index.Also, as the subcarrier activation pattern of the proposed scheme match the binary numbers, low complexity log-likelihood ratio (LLR) detection was made easy to adopt and bit error rate (BER) performance was maintained good.Theoretical analysis and simulation results show that the proposed scheme effectively improves the SE and BER performance over classical OFDM-IM scheme in additive white Gaussian noise (AWGN) channels and Rayleigh fading channels.…”
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Improved SLM algorithm for PAPR reduction in OFDM system by Ce JI, Wenjing ZHU, Ying WEI, Dianxia JIA

“…In order to reduce the peak to average power ratio (PAPR) of the conventional selective mapping (SLM) algorithm,decrease the transmission of side-band information,and improve the spectral efficiency in the orthogonal frequency division multiplexing (OFDM) system,the TL-SLM algorithm based on the conversion matrix and the chaotic sequence was proposed firstly.Although the TL-SLM algorithm could effectively decrease the transmission of side-band information,the reduction of PA P R was limited.To solve this problem,an improved TL-SLM algorithm based on the rotation vector was proposed,which was the TR-SLM algorithm.TR-SLM algorithm introduced the rotation vector to generate more time-domain alternative signals to further reducing the PA P R.The performance analysis shows that although the TL-SLM algorithm and the TR-SLM algorithm increase the complexity a little,the PA P R performance is effectively improved and the transmission of side-band information is greatly reduced.…”
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Robust Preamble-Based Timing Synchronization for OFDM Systems by Yun Liu, Fei Ji, Hua Yu, Dehuan Wan, Fangjiong Chen, Ling Yang

“…This study presents a novel preamble-based timing offset estimation method for orthogonal frequency division multiplexing (OFDM) systems. The proposed method is robust, immune to the carrier frequency offset (CFO), and independent of the structure of the preamble. …”
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Design of OFDM-IM system based on IRS-assisted by Mengmeng ZHAO, Liming HE, Fangfang LIU

“…Index modulation (IM) and intelligent reflecting surface (IRS) are emerging mobile communication technologies.In order to improve the reliability of traditional orthogonal frequency division multiplexing (OFDM) system, an orthogonal frequency division multiplexing with index modulation (OFDM-IM) system based on IRS-assisted was designed.Firstly, the OFDM-IM system was designed by using spatial modulation and frequency domain modulation to increase the Euclidean distance between subcarriers.Then, by establishing an equivalent circuit model, a practical IRS model was obtained.Finally, an alternating optimization algorithm was used to optimize the active transmission power of the access point (AP) and passive beamforming of the IRS jointly.The simulation results show that compared to the benchmark scheme, the symbol error rate (SER) or bit error rate (BER) of the OFDM-IM system based on IRS-assisted can be reduced by 60%～90%.Especially in the case of high signal-to-noise ratio, the SER or BER of the system can reach 1.0×10^-6, which indicates that the introduction of IM and IRS technologies has optimized the link transmission quality of end-to-end communication system.In addition, based on the IRS-assisted OFDM-IM system as the standard, simulations are conducted to demonstrate the impact of various parameters from the IRS model and IM.It concludes that the parameters in the system should be selected reasonably according to channel state information (CSI).…”
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Constructions of Golomb Costas arrays and their applications in OFDM systems by Jian-guo YAO, Yu-feng WANG, Wei HENG

“…The design of frequency hopping codes and the distribution of them to the users were illustrated while the design of frequency hopping patterns was explored in OFDM system with Golomb Costas arrays with 1-gap row and 1-gap column. …”
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Pilot-assisted non-cyclic prefixed SFBC-OFDM by REN Shu-bo, SHANG Yong, GUO Jun-qi, XIANG Hai-ge

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İBÂDÎLİK ARAŞTIRMALARINDA ÖNEMLİ BİR İSİM: TADEUSZ LEWICKI by Harun Yıldız

“…Ortadoğu coğrafyasında yaşayan dinî grup ve mezhepler arasında, özellikletarihsel anlamda Hâricîliğin günümüzde yaşayan en önemli kolu olmasınedeniyle İbâdîlik, önemli bir yere sahiptir. …”
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Nonconvective Forces: A Critical and Often Ignored Component in the Echocardiographic Assessment of Transvalvular Pressure Gradients by Michael S. Firstenberg, Erik E. Abel, Thomas J. Papadimos, Ravi S. Tripathi

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Motion – All Patients with GERD Should Be Offered Once in a Lifetime Endoscopy: Arguments for the Motion by David Armstrong

“…Because of the difficulty in distinguishing dysplasia from inflammatory and regenerative changes, endoscopy should be undertaken while the patient is on effective antisecretory therapy. Endoscopy should be offered only to patients who are suitable for further therapy (especially esophagectomy), and only if they understand the implications of abnormal findings. …”
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“They all offered different support”: Integrated support systems for academic resilience among engineering students by Curwyn Mapaling

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Announcement effect of tender offer share buyback around turmoil period – evidence from India by Suresha B., Kavitha Desai, Rejoice Thomas, Nijumon K John, Elizabeth Renju Koshy

“…The study considered the stocks listed in the National Stock Exchange (NSE) that offered share buyback under tender offer mode during the pre-pandemic period between April 2016 and February 2020 and the post-pandemic period between March 2020 and March 2022. 75 firms in the pre-pandemic period and 43 in the post-pandemic period that announced share buyback under the tender offer method were analyzed. …”
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A produção da ordem no Presídio Central de Porto Alegre pela Polícia Militar by Letícia Maria Schabbach, Iara Cunha Passos

“…Resumo Este artigo analisa a gestão da Polícia Militar, denominada de Brigada Militar (BM), no Presídio Central de Porto Alegre (PCPA), que perdura desde 1995, buscando compreender quais os procedimentos utilizados na produção da ordem prisional (quanto à organização dos espaços, à relação com os detentos e às especificidades da instituição policial militar). …”
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Retracted: Empirical Research on Seasoned Equity Offerings, Board Member Characteristics, and Corporate Investment Efficiency by Discrete Dynamics in Nature and Society

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mtlA, a novel typing gene offering enhanced resolution for pandemic Vibrio species by Lei Zhou, Danlei Liu, Zilong Zhang, Yongqiang Zhu, Huajun Zheng

“…Our findings revealed its ubiquitous presence across typical pathogenic Vibrio species, offering superior typing efficacy compared with MLST and more extensive implications.…”
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Strafferetlig forfølgelse af menneskehandel til prostitution i Danmark: Hvilken retsbeskyttelse får ofrene? by Annick Prieur

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Ordem vermelha: filhos da degradação, entre a alta fantasia e a distopia by Bruno Anselmi Matangrano

“…A través de las recientes discusiones alrededor de lo insólito en la literatura, este artículo pretende mostrar el carácter innovador en la construcción del mundo de Untherak en el libro Ordem vermelha: filhos da degradação (Orden roja: hijos de la degradación), de Felipe Castilho, obra que subvierte las convenciones de la “alta fantasía” al introducir elementos de la “distopía”, modo narrativo que ha conquistado importante espacio en la contemporaneidad por traer discusiones políticas y sociales despertadas por la fuerte ola conservadora de la segunda década del siglo XXI y cuyas características básicas divergen bastante de las teorías en torno a la fantasía.…”
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What Does Digitalization Offer to English for Specific Purposes Learning? : A Systematic Literature Review by Sri Yunita, Susilawati Susilawati, Riadi Darwis, Arrizqi Ramadhan

“…This study aims to discover what digitalization offers to promote students' learning in ESP classrooms and the contributions of lecturer digital competency to student learning.  …”
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