摘要:

AbstractBased on the property that correction coding is more sensitive to the number of errors than the number of erased code symbols, results of an analytical investigation to improve the performance of concatenated coding communications are presented. We propose a new tactic, ‘signal editing’, to estimate and erase unreliable data prior to the final outer decoding process. We show that signal editing has a capability to detect and delete individual erroneous digits that has not been achieved by other methods. As a result, system performance can be markedly improved. Specific recommendations for using the procedure are suggested and discussed.We illustrate how signal editing is implemented in the case of a convolutional code with Viterbi decoding. A new concatenated (or hybrid) coding technique is constructed integrating the code with interleaving and signal editing. Performance improvement is evaluated and analysed. In this study, signal editing is derived from the information available in the Viterbi decoding process. Not limited to convolutional code with Viterbi decoding, signal editing can be applied to other linear codes without any restrict

ISSN:0737-2884    

DOI:10.1002/sat.4600100102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractIn digital satellite‐to‐earth transmission the entry of substantial undesired solar radiation into the receiver antenna is sometimes unavoidable. When the signal transmission takes the form of incoherent optical pulse position modulation (PPM) the parameters of signal and consequent intense noise can fall outside the range of routinely available classical numerical results on symbol error probability.This paper presents an alternative system for parametrization of signal and noise in theclassicalPPM channel, i.e. that characterized by Poisson photon arrival statistics for signal itself, the noise itself, and the signal plus noise.The resulting formulation for error probability, the scheme for probability calculation, and the simple, compact plots of error probability versus newly conceived parameters cover the entire range of signal and noise intensities, from weakest to strongest.Of course, when properly interpreted the new results agree entirely with classically available numerical results within the parametric range of the for

ISSN:0737-2884    

DOI:10.1002/sat.4600100103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper analyses and compares possible access schemes to be used in satellite networks with a large number of small earth‐stations. Basically, frequency division (FDMA), time division (TDMA), and spread spectrum multiple access (SSMA) are considered. For TDMA, one single carrier originated in one particular earth‐station is transmitted in each sub‐band and therefore a single‐channel‐per‐carrier system results (SCPC/FDMA). For TDMA and SSMA, it is assumed that groups of earth‐stations using either of these access schemes share the full available band in FDMA. The corresponding systems are thus TDMA/FDMA and SSMA/FDMA. Moreover, for SCPC/FDMA and TDMA/FDMA individual carriers may be spread to the extent that the available bandwidth is always fully occupied. Spectral efficiencies for these three access modes (Spread SCPC/FDMA, Spread TDMA/FDMA and SSMA/FDMA) are computed and compared for transmission through a non‐linear satellite channel and optimum operating points for the non‐linear amplifier are also determined. Comparisons are also performed for the situation in which transmitting earth‐stations are bounded to obey an off‐axi

ISSN:0737-2884    

DOI:10.1002/sat.4600100104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe ALOHA protocol has been proposed for accessing reservation channels in demand‐assigned channel access protocols for land mobile satellite communications networks. This paper provides a rigorous performance analysis of both the slotted ALOHA protocol and two‐packet replication ALOHA protocol taking into account the effects of the fading multipath communications environment. Throughput, delay and stability of these two protocols are determined using a Gilbert channel error model with memory. Comparison of slotted ALOHA and two‐packet replication ALOHA shows that a smaller average delay can be achieved by replication. Moreover average throughput is improved in some cases. However replication reduces stab

ISSN:0737-2884    

DOI:10.1002/sat.4600100105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:0737-2884    

DOI:10.1002/sat.4600100106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:0737-2884    

DOI:10.1002/sat.4600100101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY