Este trabalho apresenta um novo algoritmo, denominado Intercalamento Temporal por Transformada de... more Este trabalho apresenta um novo algoritmo, denominado Intercalamento Temporal por Transformada de Fourier (FTI), desenvolvido para complementar sistemas de modulação digital. Com este processo, a informação é distribuida de forma difusa ao longo de um conjunto de símbolos, tanto no domínio do tempo como no da frequência. Constitui-se em um processo computacionalmente eficiente, especialmente adequado para operar em conjunto com a modulação OFDM, e que apresenta consideráveis ganhos de desempenho em algumas situações de degradação; por exemplo, é mais tolerante a ruídos impulsivos de longa duração do que a modulação OFDM convencional. Apresenta-se também um outro mecanismo, denominado de Realimentação de Erro, que melhora o desempenho do sistema em praticamente todas as situaçoes analisadas. Embora implique em aumento da carga computacional, este processo consiste de uma operação determinística, que dispensa etapas de iteração ou recursos computacionais distintos dos já disponíveis. ...
– This work introduces a new transform-based time interleaving algorithm: FTI-OFDM (Fourier Trans... more – This work introduces a new transform-based time interleaving algorithm: FTI-OFDM (Fourier Transform Interleaved OFDM) in which binary information is spread over several consecutive symbols that can be further scrambled in the frequency domain. Simulations are used to show its superiority over the usual binary time interleaving used in ordinary OFDM under several impairment scenarios that include impulsive noise and deep fading.
-A prototype of a very high dynamic range 32-bits Digital to Analog Converter (DAC) was designed ... more -A prototype of a very high dynamic range 32-bits Digital to Analog Converter (DAC) was designed and built for the purpose of direct auditory stimulus generation. It provides signals from less than 100 nV up to 50 Watts peak power output, driving a 32-Ohms earphone or speaker. The use of ternary cells makes possible a 170 dB dynamic range that is basically limited by thermal noise only.
A prototype of a very high dynamic range 32-bits Digital to Analog Converter (DAC) was designed a... more A prototype of a very high dynamic range 32-bits Digital to Analog Converter (DAC) was designed and built for the purpose of direct auditory stimulus generation. It provides signals from less than 100 nV up to 50 Watts peak power output, driving a 32-Ohms earphone or speaker. The use of ternary cells makes possible a 170 dB dynamic range that is basically limited by thermal noise only.
In this paper we consider the problem of asynchronous CDMA (Code Division Multiple Access) system... more In this paper we consider the problem of asynchronous CDMA (Code Division Multiple Access) systems performance optimization by proper selection of spreading sequences (codes). The computational complexity involved induces the search for sub-optimal procedures and the numerical method of "simulated annealing" is applied for this particular problem. Despite the simplicity and arbitrariness of the algorithm, the results are amazing. These results confirm the possibility of performance improvement by sequence selection using the method of simulated annealing. Its advantage, in terms of argument of function Q(.) (assuming "strong signal", that is, negligible No/A2.T), is = l.OdB when we compare, for a single user, the worst and best cases.
This work introduces a new transform-of several scenarios (Sec V) are followed by conclusions bas... more This work introduces a new transform-of several scenarios (Sec V) are followed by conclusions based time interleaving algorithm: FTI-OFDM (Fourier summarized in Sec. VI. Transform Interleaved OFDM) in which binary
A prototype of a very high dynamic range 32-bits Digital to Analog Converter (DAC) was designed a... more A prototype of a very high dynamic range 32-bits Digital to Analog Converter (DAC) was designed and built for the purpose of direct auditory stimulus generation. It provides signals from less than 100 nV up to 50 Watts peak power output, driving a 32-Ohms earphone or speaker. The use of ternary cells makes possible a 170 dB dynamic range that is basically limited by thermal noise only.
Este trabalho apresenta um novo algoritmo, denominado Intercalamento Temporal por Transformada de... more Este trabalho apresenta um novo algoritmo, denominado Intercalamento Temporal por Transformada de Fourier (FTI), desenvolvido para complementar sistemas de modulação digital. Com este processo, a informação é distribuida de forma difusa ao longo de um conjunto de símbolos, tanto no domínio do tempo como no da frequência. Constitui-se em um processo computacionalmente eficiente, especialmente adequado para operar em conjunto com a modulação OFDM, e que apresenta consideráveis ganhos de desempenho em algumas situações de degradação; por exemplo, é mais tolerante a ruídos impulsivos de longa duração do que a modulação OFDM convencional. Apresenta-se também um outro mecanismo, denominado de Realimentação de Erro, que melhora o desempenho do sistema em praticamente todas as situaçoes analisadas. Embora implique em aumento da carga computacional, este processo consiste de uma operação determinística, que dispensa etapas de iteração ou recursos computacionais distintos dos já disponíveis. ...
– This work introduces a new transform-based time interleaving algorithm: FTI-OFDM (Fourier Trans... more – This work introduces a new transform-based time interleaving algorithm: FTI-OFDM (Fourier Transform Interleaved OFDM) in which binary information is spread over several consecutive symbols that can be further scrambled in the frequency domain. Simulations are used to show its superiority over the usual binary time interleaving used in ordinary OFDM under several impairment scenarios that include impulsive noise and deep fading.
-A prototype of a very high dynamic range 32-bits Digital to Analog Converter (DAC) was designed ... more -A prototype of a very high dynamic range 32-bits Digital to Analog Converter (DAC) was designed and built for the purpose of direct auditory stimulus generation. It provides signals from less than 100 nV up to 50 Watts peak power output, driving a 32-Ohms earphone or speaker. The use of ternary cells makes possible a 170 dB dynamic range that is basically limited by thermal noise only.
A prototype of a very high dynamic range 32-bits Digital to Analog Converter (DAC) was designed a... more A prototype of a very high dynamic range 32-bits Digital to Analog Converter (DAC) was designed and built for the purpose of direct auditory stimulus generation. It provides signals from less than 100 nV up to 50 Watts peak power output, driving a 32-Ohms earphone or speaker. The use of ternary cells makes possible a 170 dB dynamic range that is basically limited by thermal noise only.
In this paper we consider the problem of asynchronous CDMA (Code Division Multiple Access) system... more In this paper we consider the problem of asynchronous CDMA (Code Division Multiple Access) systems performance optimization by proper selection of spreading sequences (codes). The computational complexity involved induces the search for sub-optimal procedures and the numerical method of "simulated annealing" is applied for this particular problem. Despite the simplicity and arbitrariness of the algorithm, the results are amazing. These results confirm the possibility of performance improvement by sequence selection using the method of simulated annealing. Its advantage, in terms of argument of function Q(.) (assuming "strong signal", that is, negligible No/A2.T), is = l.OdB when we compare, for a single user, the worst and best cases.
This work introduces a new transform-of several scenarios (Sec V) are followed by conclusions bas... more This work introduces a new transform-of several scenarios (Sec V) are followed by conclusions based time interleaving algorithm: FTI-OFDM (Fourier summarized in Sec. VI. Transform Interleaved OFDM) in which binary
A prototype of a very high dynamic range 32-bits Digital to Analog Converter (DAC) was designed a... more A prototype of a very high dynamic range 32-bits Digital to Analog Converter (DAC) was designed and built for the purpose of direct auditory stimulus generation. It provides signals from less than 100 nV up to 50 Watts peak power output, driving a 32-Ohms earphone or speaker. The use of ternary cells makes possible a 170 dB dynamic range that is basically limited by thermal noise only.
Uploads
Papers by GUIDO STOLFI