The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Kun-wah Yip - One of the best experts on this subject based on the ideXlab platform.
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eve Expansion of the WSSUS Channel Output and Its Application to Efficient Simulation
1997Co-Authors: Kun-wah YipAbstract:This paper derives a Karhunen-Lo` eve (K-L) expan- sion of the time-varying output of a multipath Rayleigh fading wide-sense-stationary uncorrelated-scattering (WSSUS) channel. It is shown that under the same mean-squared Error Condition, the number of terms required by the truncated K-L expansion is less than that of the series expansion obtained by using the discrete-path approximation of the channel so that simulation using the K-L expansion is more efficient. This computational advantage becomes more significant as higher simulation accu- racy is required. The derived K-L expansion is applied to develop an efficient simulation technique for digital transmission over a multipath Rayleigh fading WSSUS channel using an optimum receiver. We show that the proposed technique requires shorter computation time than two other known simulation techniques.
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Karhunen-Loeve expansion of the WSSUS channel output and its application to efficient simulation
IEEE Journal on Selected Areas in Communications, 1997Co-Authors: Kun-wah YipAbstract:This paper derives a Karhunen-Loeve (K-L) expansion of the time-varying output of a multipath Rayleigh fading wide-sense-stationary uncorrelated-scattering (WSSUS) channel. It is shown that under the same mean-squared Error Condition, the number of terms required by the truncated K-L expansion is less than that of the series expansion obtained by using the discrete-path approximation of the channel so that simulation using the K-L expansion is more efficient. This computational advantage becomes more significant as higher simulation accuracy is required. The derived K-L expansion is applied to develop an efficient simulation technique for digital transmission over a multipath Rayleigh fading WSSUS channel using an optimum receiver. We show that the proposed technique requires shorter computation time than two other known simulation techniques.
Herbert C. Goltz - One of the best experts on this subject based on the ideXlab platform.
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Saccadic adaptation in visually normal individuals using saccadic endpoint variability from amblyopia.
Investigative ophthalmology & visual science, 2015Co-Authors: Rana Arham Raashid, Agnes M. F. Wong, Alan Blakeman, Herbert C. GoltzAbstract:PURPOSE: Saccadic adaptation is affected by the spatial variability of the adapting Error signal. Recently, we have shown that saccadic adaptation is reduced in anisometropic amblyopia, possibly impacted by spatially imprecise saccades. Here, we tested this idea by quantifying the saccadic endpoint variability difference between people with anisometropic amblyopia and visually normal individuals. We then applied this difference to the second target step distribution during saccadic adaptation in visually normal people to test whether their performance diminished to a similar extent as participants with amblyopia. METHODS: Ten visually normal adults performed a double-step adaptation task (±19°, followed by 4° back-steps) with the nondominant eye under two Conditions: "consistent Error," using a constant back-step; and "variable Error," using a variable (σdiff) back-step determined by subtracting the saccadic endpoint variability in controls from that in anisometropic amblyopia during amblyopic/nondominant eye viewing. Percentage change in saccadic gains, percentage retention, and adaptation time constants were analyzed. RESULTS: Percentage change in saccadic gains decreased significantly during the variable Error Condition (50% ± 10%) compared to the consistent Error Condition (69% ± 9%; P = 0.0008). Percentage retention and time constants did not differ between Conditions. The adaptation magnitude during the variable Error Condition was comparable to the previous percentage adaptation in people with anisometropic amblyopia during the consistent Error Condition with amblyopic eye viewing. CONCLUSIONS: Our findings indicate that adding exogenous spatial noise to the adapting step consistent with the saccadic endpoint variability difference between amblyopic and visually normal groups is sufficient to reduce saccadic adaptation in healthy individuals.
Liang-gee Chen - One of the best experts on this subject based on the ideXlab platform.
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Low-delay and Error-robust wireless video transmission for video communications
IEEE Transactions on Circuits and Systems for Video Technology, 2002Co-Authors: Tu-chih Wang, Hung-chi Fang, Liang-gee ChenAbstract:Video communications over wireless networks often suffer from various Errors. A novel video transmission architecture is proposed to meet the low-delay and Error-robust requirement of wireless video communications. This architecture uses forward Error correction coding and automatic repeat request (ARQ) protocol to provide efficient bandwidth access from wireless link. In order to reduce ARQ delay, a video proxy server is implemented at the base station. This video proxy not only reduces the ARQ response time, but also provides Error-tracking functionality. The complexity of this video proxy server is analyzed. Experiment shows that about 8.9% of the total macroblocks need to be transcoded under a random-Error Condition of 10/sup -3/ Error probability. Because H.263 is the most popular video coding standard for video communication, we use it as an experiment platform. A data-partition scheme is also used to enhance Error-resilience performance. This architecture is also suitable for various motion-compensation-based standards like H.261, H.263 series, MPEG-1, MPEG-2, MPEG-4, and H.264. For "Foreman" sequence under a random-Error Condition of 10/sup -3/ Error probability, luminance peak signal-to-noise ratio decreases only 0.35 dB, on average.
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ICME (1) - Low delay, Error robust wireless video transmission architecture for video communication
Proceedings. IEEE International Conference on Multimedia and Expo, 1Co-Authors: Tu-chih Wang, Hung-chi Fang, Liang-gee ChenAbstract:In this paper, a novel video transmission architecture is proposed to meet the low-delay and Error robust requirement of wireless video communications. This architecture uses FEC coding and ARQ protocol to provide efficient bandwidth access from wireless link. In order to reduce ARQ delay, a video proxy server is implemented at the base station. This video proxy not only reduces the ARQ response time but also provides Error tracking functionality. We use H.263 as the experimental platform for our architecture. Experiments show that average luminance PSNR decreases only 0.35db for the "Foreman" sequence under a random Error Condition of 10/sup -3/ Error probability.
Rana Arham Raashid - One of the best experts on this subject based on the ideXlab platform.
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Saccadic adaptation in visually normal individuals using saccadic endpoint variability from amblyopia.
Investigative ophthalmology & visual science, 2015Co-Authors: Rana Arham Raashid, Agnes M. F. Wong, Alan Blakeman, Herbert C. GoltzAbstract:PURPOSE: Saccadic adaptation is affected by the spatial variability of the adapting Error signal. Recently, we have shown that saccadic adaptation is reduced in anisometropic amblyopia, possibly impacted by spatially imprecise saccades. Here, we tested this idea by quantifying the saccadic endpoint variability difference between people with anisometropic amblyopia and visually normal individuals. We then applied this difference to the second target step distribution during saccadic adaptation in visually normal people to test whether their performance diminished to a similar extent as participants with amblyopia. METHODS: Ten visually normal adults performed a double-step adaptation task (±19°, followed by 4° back-steps) with the nondominant eye under two Conditions: "consistent Error," using a constant back-step; and "variable Error," using a variable (σdiff) back-step determined by subtracting the saccadic endpoint variability in controls from that in anisometropic amblyopia during amblyopic/nondominant eye viewing. Percentage change in saccadic gains, percentage retention, and adaptation time constants were analyzed. RESULTS: Percentage change in saccadic gains decreased significantly during the variable Error Condition (50% ± 10%) compared to the consistent Error Condition (69% ± 9%; P = 0.0008). Percentage retention and time constants did not differ between Conditions. The adaptation magnitude during the variable Error Condition was comparable to the previous percentage adaptation in people with anisometropic amblyopia during the consistent Error Condition with amblyopic eye viewing. CONCLUSIONS: Our findings indicate that adding exogenous spatial noise to the adapting step consistent with the saccadic endpoint variability difference between amblyopic and visually normal groups is sufficient to reduce saccadic adaptation in healthy individuals.
Agnes M. F. Wong - One of the best experts on this subject based on the ideXlab platform.
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Saccadic adaptation in visually normal individuals using saccadic endpoint variability from amblyopia.
Investigative ophthalmology & visual science, 2015Co-Authors: Rana Arham Raashid, Agnes M. F. Wong, Alan Blakeman, Herbert C. GoltzAbstract:PURPOSE: Saccadic adaptation is affected by the spatial variability of the adapting Error signal. Recently, we have shown that saccadic adaptation is reduced in anisometropic amblyopia, possibly impacted by spatially imprecise saccades. Here, we tested this idea by quantifying the saccadic endpoint variability difference between people with anisometropic amblyopia and visually normal individuals. We then applied this difference to the second target step distribution during saccadic adaptation in visually normal people to test whether their performance diminished to a similar extent as participants with amblyopia. METHODS: Ten visually normal adults performed a double-step adaptation task (±19°, followed by 4° back-steps) with the nondominant eye under two Conditions: "consistent Error," using a constant back-step; and "variable Error," using a variable (σdiff) back-step determined by subtracting the saccadic endpoint variability in controls from that in anisometropic amblyopia during amblyopic/nondominant eye viewing. Percentage change in saccadic gains, percentage retention, and adaptation time constants were analyzed. RESULTS: Percentage change in saccadic gains decreased significantly during the variable Error Condition (50% ± 10%) compared to the consistent Error Condition (69% ± 9%; P = 0.0008). Percentage retention and time constants did not differ between Conditions. The adaptation magnitude during the variable Error Condition was comparable to the previous percentage adaptation in people with anisometropic amblyopia during the consistent Error Condition with amblyopic eye viewing. CONCLUSIONS: Our findings indicate that adding exogenous spatial noise to the adapting step consistent with the saccadic endpoint variability difference between amblyopic and visually normal groups is sufficient to reduce saccadic adaptation in healthy individuals.