Navegando por Assunto "PSNR - Peak signal to noise ratio"

Agora exibindo 1 - 3 de 3

Acesso aberto (Open Access)
Análise de desempenho de códigos concatenados em canais AWGN e com multipercursos: uma abordagem baseada em transmissão de vídeo em 4K codificado em H.264
(Universidade Federal do Pará, 2017-03-10) COSTA, Thiago de Araújo; PELAES, Evaldo Gonçalves; http://lattes.cnpq.br/0255430734381362
In the process of digital transmission the communication channel inserts a series of imperfections in the information transmitted. In order to improve the quality of digital multimedia broadcasting, a number of technologies, such as DVB-T (Digital Video Broadcasting Terrestrial) and DVB-T2 (Digital Video Broadcasting Terrestrial-2nd Generation) employing channel coding techniques have been developed. Within this context, channel coding techniques are of great importance because they minimize the probability of error during the transmission of the information. Thus it becomes important to evaluate the performance of the channel encoders. This dissertation performs a comparative analysis of the concatenated RS-CONV and BCH-LDPC encoders (They are implemented in Digital TV) over the AWGN and Rayleigh channels; Both in terms of BER, as well as in terms of video quality through the PSNR and SSIM metrics. In simulations over the AWGN channel the concatenated pair BCH-LDPC obtained the best performance in conjunction with the QPSK modulation, reaching the value of BER equal 0 when 𝐸𝑏/𝑁0 equals 1 dB. In the Rayleigh channel simulations, the BCH-LDPC association with the QPSK modulation presented the best results, reaching the BER equal 0 from 𝐸𝑏/𝑁0 equal 3 dB. In the video quality evaluation the BCHLDPC concatenated pair showed a superiority over the RS-CONV in the studied channels, in such a way that it conferred an increase (gain) on the mean of the PSNR in relation to the RS-CONV, that for the channel AWGN was approximately 2.2 dB, 6.4 dB and 6.7 dB, respectively for QPSK, 16-QAM and 64-QAM. In the Rayleigh channel the values were approximately 3.9 dB, 4.2 dB and 1.6 dB, respectively for QPSK, 16-QAM and 64-QAM. To confirm the results, another analysis is performed for a given band of the video, showing an increase in the mean of the results of the BCH-LDPC in relation to the RS-CONV, which for the AWGN channel was 15.8 dB for QPSK; 22.23 dB for 16-QAM and 14.3 dB for 64-QAM. While for Rayleigh channel the increase was 16.8 dB, 10.3 dB and 1.4 db, respectively, for QPSK, 16-QAM and 64-QAM.
Acesso aberto (Open Access)
Modelagem paramétrica linear aplicada à faixa de sinal de televisão digital para cidades densamente arborizadas
(Universidade Federal do Pará, 2014-02-26) LOPES, Ramz Luiz Fraiha; CAVALCANTE, Gervásio Protásio dos Santos; http://lattes.cnpq.br/2265948982068382
This work proposes a linear parametric (auto-regressive) model applicable to digital television and mobile phone signals propagation studies on densely arborized cities. The proposed model has a strong statistic basis and depends only on measured data, in case, power signal and PSNR (Peak Signal-to-Noise Ratio) values data. A genetic algorithm was used to adjust the parameters of the model to a measured data set. This work was carried out on the digital television frequency and the signal power level and PSNR values were analyzed. Measurement campaigns were carried out in Belém city. Power signal data was collected as well as videos form the daily schedule of a television station. The results indicate that the model applicability is feasible on planning telecommunication services.
Acesso aberto (Open Access)
Qualidade de vídeo baseada em perda de pacotes utilizando o padrão IEEE 802.11AC
(Universidade Federal do Pará, 2017-03-10) MATOS, Edemir Marcus Carvalho de; CASTRO, Bruno Souza Lyra; http://lattes.cnpq.br/1897829604434609; PELAES, Evaldo Gonçalves; http://lattes.cnpq.br/0255430734381362
The flow of digital multimedia information in wireless networks has grown exponentially due to the popularization of the IEEE 802.11 Standards as access technology, as well as the increase of devices (clients) that operate in this standard. High-resolution video streaming is also becoming commonplace in these networks, driving the development of more efficient CODECs. In this context, some QoE and QoS metrics must be met to deliver quality content to the end user. This dissertation studies the behavior of wireless video streaming using the IEEE 802.11ac standard operating in the 5.2 GHz range, the CODEC rated is the H.264 / AVC for the 720p, 1080p and 2160p resolutions. From the packet loss simulations during video transmission an estimate of the average loss of PSNR for each resolution was developed, finding the relation of the loss of video quality varying the resolution in function of the loss of packets. The proposed model presented good results when compared to the real data, obtaining RMSE of 2.32 dB and standard deviation of 2.2 dB. This modeling can aid in communication network planning as well as enhancement of new source encoders, resulting in a better quality of experience.