dicode pulse position modulation (DiPPM) has been considered as a solution for the bandwidth consumption issue that other existing pulsepositionmodulation (PPM) formats suffer from. This is because it has a line rat...
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ISBN:
(纸本)9781479914203
dicode pulse position modulation (DiPPM) has been considered as a solution for the bandwidth consumption issue that other existing pulsepositionmodulation (PPM) formats suffer from. This is because it has a line rate that is twice that of the original data rate. This paper considers for the first time forward error correction (FEC) Reed Solomon (RS) codes to improve the error performance of a DiPPM. The results show that the error performance in the system can be improved by using FEC code when the RS is working at its optimum parameters. The error performance of the uncoded DiPPM system has been compared with a RS coded DiPPM system and one using maximum likelihood sequence detector (MLSD) in terms of the number of photons per pulse, transmission efficiency, and bandwidth expansion. The DiPPM with RS code offers superior performance compared to the uncoded DiPPM and DiPPM using MLSD, requiring only 4.5 x 10(3) photons per pulse, when operating at a bandwidth equal or above to 0.9 times the original data rate. This is with an optimum code rate of approximately 3/4, and a codeword length of 2(5).
dicode pulse position modulation (DiPPM) has been considered as a solution for the bandwidth consumption issue that other existing pulsepositionmodulation (PPM) formats suffer from. This is because it has a line rat...
详细信息
ISBN:
(纸本)9781479914180
dicode pulse position modulation (DiPPM) has been considered as a solution for the bandwidth consumption issue that other existing pulsepositionmodulation (PPM) formats suffer from. This is because it has a line rate that is twice that of the original data rate. This paper considers for the first time forward error correction (FEC) Reed Solomon (RS) codes to improve the error performance of a DiPPM. The results show that the error performance in the system can be improved by using FEC code when the RS is working at its optimum parameters. The error performance of the uncoded DiPPM system has been compared with a RS coded DiPPM system and one using maximum likelihood sequence detector (MLSD) in terms of the number of photons per pulse, transmission efficiency, and bandwidth expansion. The DiPPM with RS code offers superior performance compared to the uncoded DiPPM and DiPPM using MLSD, requiring only 4.5 × 10~3 photons per pulse, when operating at a bandwidth equal or above to 0.9 times the original data rate. This is with an optimum code rate of approximately 3/4, and a codeword length of 2~5.
It is shown that the dicode pulse position modulation (DiPPM) scheme, presented in this study, demonstrates several key advantages in comparison with other existing PPM schemes, because of the compact structure and ef...
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It is shown that the dicode pulse position modulation (DiPPM) scheme, presented in this study, demonstrates several key advantages in comparison with other existing PPM schemes, because of the compact structure and efficient recovery process of the clock signal. An error corrector for the DiPPM scheme is presented, where experimental results prove the theoretical expectations of a previous publication. Thus, it is demonstrated that DiPPM with the use of a maximum likelihood sequence detector (MLSD) error corrector, significantly reduces or eliminates errors incurred during the transmission. Comparison of and discussion on the outcomes of a DiPPM system with and without the error corrector are included.
The rapid and significant development of communications links between satellites has made it possible to use various applications such as relay voice, video, multimedia, etc. As a result, much research has been carrie...
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The rapid and significant development of communications links between satellites has made it possible to use various applications such as relay voice, video, multimedia, etc. As a result, much research has been carried out in this field during recent years to reduce power consumption and increase transmission reliability. This reported work focuses on analysis of intersatellite links in free space, with optical links using laser sources being considered in particular. The use of several different coding schemes are discussed for use in such links: multiple pulsepositionmodulation (MPPM);digital pulsepositionmodulation (DPPM);dicode pulse position modulation (dicode PPM). Work has been carried out to compare these coding schemes in terms of error weightings and coding efficiency through showing how the PCM error rate is affected by false alarm and erasure errors for MPPM, DPPM and dicode PPM coding 3 bits of PCM. Comparison between these coding schemes is drawn in terms of sensitivity and bandwidth efficiency.
PINFET receivers have been considered for use in digital pulsepositionmodulation (PPM) links, where they can give sensitivities far greater than that achievable with pulse code modulation (PCM). However, digital PPM...
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PINFET receivers have been considered for use in digital pulsepositionmodulation (PPM) links, where they can give sensitivities far greater than that achievable with pulse code modulation (PCM). However, digital PPM suffers from a very large bandwidth expansion factor, resulting in line rates that can be prohibitively high. An alternative is dicode PPM and the paper is concerned with the use of a PINFET receiver and a noise-whitened matched filter in such a scheme. With this particular implementation, the line rate is four times that of the PCM, making it a viable alternative to digital PPM. The original analysis presented predicts that such a system can give a sensitivity of -59.51 dBm when operating with high fibre bandwidth and 155.52 Mbit/s PCM data. The impact of intersymbol interference is also studied and it is shown that the system can offer a sensitivity of -53.33 dBm at a bandwidth of 1.5 times the PCM bit-rate. These sensitivities should be compared with a predicted PCM sensitivity of -51.95 dBm when operating in a high-bandwidth link.
dicode pulse position modulation (PPM) is a new modulation format that offers improved sensitivity over digital PPM but at a reduced line-rate. For the first time, the spectral characterisation of the dicode PPM modul...
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dicode pulse position modulation (PPM) is a new modulation format that offers improved sensitivity over digital PPM but at a reduced line-rate. For the first time, the spectral characterisation of the dicode PPM modulation format is considered and original expressions for predicting both the continuous and discrete spectrum are presented.
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