摘要:

AbstractA new class of generalized intersymbol‐interference and jitter‐free (GIJF) modulated signals is introduced. Computer simulation and hardware experimental research results demonstrate that our proposed new generation of signals and modulators leads to significant performance improvements in non‐linearly amplified broadband radio systems. For increased power efficiency, non‐linear amplification is required in most commercial satellite and terrestrial microwave systems. In particular, we demonstrate that the 3 dB envelope fluctuation of currently used offset raised‐cosine overlapped QPSK systems is reduced to 0‐5 dB, and that the BER performance is improved by approximately 1 dB. These significant technical performance advantages are expected to lead to more economical implementations of digital transmiss

ISSN:0737-2884    

DOI:10.1002/sat.4600090302

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

年代:1991

数据来源: WILEY

摘要:

AbstractA new class of spectral and power efficient offset modes of the M‐ary QAM modulation technique, 64SQAM (superposed QAM), is analysed. The power spectrum of 64SQAM reveals a fast spectral roll‐off and a low out‐of‐band energy.P(e) performance is analysed with different baseband wave shapes of 64SQAM in AWGN linear channels. For the operation ofM‐ary QAM at the highest power efficiency (i.e. at the saturation mode of HPA), a new bandwidth compressive NLA (non‐linearly amplified) 64SQAM is investigated. Retaining a compact power spectrum and allowing a simple filtering strategy, NLA‐64SQAM operates within 0–75 dBC/Ndegradatio

ISSN:0737-2884    

DOI:10.1002/sat.4600090303

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

年代:1991

数据来源: WILEY

摘要:

AbstractIn the recent development of phased array/distributed amplifier systems for application to mobile satellite or thin route communication systems, the intermodulation (IM) generated by the element amplifiers is spatially dispersed in such a way that some of the IM radiated energy falls outside the intended beam area. In addition, some of the IM falling inside the beam area has frequencies different from the carriers intended for that area.It is known that for fixed beam systems with frequency reuse, an average IM noise reduction of several dB can be realized. In the specific case under investigation, of four beams, nine frequencies and 12 carriers (1‐33 frequency reuse factor), an IM improvement of about 2‐0 dB is realized. The improvement in carrier‐to‐IM‐noise ratio can be applied to increase system capacity, or for given capacity it can be used to reduce RF power amplifier back‐off, which can be translated into a reduction of spacecraft prime power requirement.The considerable advantage gained from the multiple beam distributed amplifier approach makes it worthwhile to explore the workings of such a system and other benefits it may offer. One of the benefits is a common RF power pool for all carriers and beams, and the other is the spatial dispersion of intermodulation (IM). A satellite multiple beam pattern and the spatial dispersion of IM products are shown

ISSN:0737-2884    

DOI:10.1002/sat.4600090304

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

年代:1991

数据来源: WILEY

摘要:

AbstractIn a mobile satellite system with a frequency reuse cellular configuration, significant co‐channel interference can be experienced due to the antenna side‐lobe level. The signal will be subjected not only to its own fading, but also to the effect of the varying degree of fading on the co‐channel interferer, and this interference will behave differently in the up and in the down‐link. This paper presents a quantitative evaluation of the combined effects of fades and co‐channel interference on a mobile satel

ISSN:0737-2884    

DOI:10.1002/sat.4600090305

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

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper combines a number of features. First the simulation of the transmission performance of aKa‐band VSAT system (CODE) is presented. The results are used to verify the systems design that was performed for CODE and to demonstrate that the implementation margin due to intermodulation noise, adjacent channel interference, filter ISI, amplifier non‐linearities and phase noise was sufficient. In the design of VSAT systems of this type phase noise was thought to be particularly important, and a new and detailed simulation of its effects is presented in the paper. For the first time, experimental measurements of system degradations have been taken on a VSAT system which have been used to verify simulation results. This was particularly important for the new phase noise simulation results and good agreement was obtained. An overall loop‐back experiment using the Ka‐band VSAT terminal with the Olympus satellite shows good agreement with the simulation results. Finally, the availability of experimental results has enabled us to compare the accuracy of TOPSIM III and BOSS simulations for the VSAT system. The paper indicates some shortcomings in the TOPSIM III simulation of phase noise and highlights the generally good agreement obtained with experimental results by the BOSS simu

ISSN:0737-2884    

DOI:10.1002/sat.4600090306

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

年代:1991

数据来源: WILEY

ISSN:0737-2884    

DOI:10.1002/sat.4600090301

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

年代:1991

数据来源: WILEY