Symbols are considered as the language of a map;hence,accurate understanding of the meaning of symbols is crucial when obtaining geographical information from a map： the symbolisation of spatial data is of key import...Symbols are considered as the language of a map;hence,accurate understanding of the meaning of symbols is crucial when obtaining geographical information from a map： the symbolisation of spatial data is of key importance in cartography.A geographical information system（GIS） provides a convenient mapping platform and powerful functions for spatial data symbolisation,while the presence of various mapping standards impedes the understanding of maps and sharing of map information.On the other hand,the available GIS platforms find it difficult to deal with automatic conversion between maps and different mapping standards.To resolve this problem,an approach for symbol recognition and automatic conversion is proposed,and a conversion system based on the approach and the Arc GIS Engine platform is developed to realise automatic conversion between maps produced based on different mapping standards.To test these conversion effects of the proposed system,the petroleum sector is chosen as the research field and the mutual conversion of a map in practical work among the three mapping standards（i.e.the Chinese Petroleum,Shell and USGS standards） governing this field is taken as a casestudy.The results show that the conversion system has a high conversion accuracy and strong applicability.展开更多
Feedforward symbol timing recovery techniques are particularly important for initial acquisition in burst modems. However, these techniques either have large calculation burden or sensitive to frequency offsets. In th...Feedforward symbol timing recovery techniques are particularly important for initial acquisition in burst modems. However, these techniques either have large calculation burden or sensitive to frequency offsets. In this paper, we proposed an efficient symbol timing recovery algorithm of MPSK signals named OMQ(Ordered Maximum power using Quadratic approximation partially) algorithm which is based on the Quadratic Approximation(QA) algorithm. We used ordered statistic sorting method to reduce the computational complexity further, meanwhile maximum mean power principle was used to decrease frequency offset sensitivity. The proposed algorithm adopts estimation-down sampling structure which is suitable for small packet size transmission. The results show that, while comparing with the QA algorithm, the computational complexity is reduced by 75% at most when 8 samples per symbol are used. The proposed algorithm shows better performance in terms of the jitter variance and sensitivity to frequency offsets.展开更多
The symbol-error-rate（SER） and power allocation for hybrid cooperative（HC） transmission system are investigated.Closed-form SER expression is derived by using the moment generating function（MGF）-based approach.H...The symbol-error-rate（SER） and power allocation for hybrid cooperative（HC） transmission system are investigated.Closed-form SER expression is derived by using the moment generating function（MGF）-based approach.However,the resultant SER contains an MGF of the harmonic mean of two independent random variables（RVs）,which is not tractable in SER analysis.We present a simple MGF expression of the harmonic mean of two independent RVs which avoids the hypergeometric functions used commonly in previous studies.Using the simple MGF,closed-form SER for HC system with M-ary phase shift keying（M-PSK） signals is provided.Further,an approximation as well as an upper bound of the SER is presented.It is shown that the SER approximation is asymptotically tight.Based on the tight SER approximation,the power allocation of the HC system is investigated.It is shown that the optimal power allocation does not depend on the fading parameters of the source-destination（SD） channel and it only depends on the source-relay（SR） and relay-destination（RD） channels.Moreover,the performance gain of the power allocation depends on the ratio of the channel quality between RD and SR.With the increase of this ratio,more performance gain can be acquired.展开更多
There is a big demand for increasing number of subscribers in the fourth generation mobile communication systems. However, the system performance is limited by multi-path propagations and lack of efficient power alloc...There is a big demand for increasing number of subscribers in the fourth generation mobile communication systems. However, the system performance is limited by multi-path propagations and lack of efficient power allocation algorithms in conventional wireless communication systems. Optimal resource allocation and interference cancellation issues are critical for the improvement of system performance such as throughput and transmission reliability. In this paper, a turbo coded bell lab space time system (TBLAST) with optimal power allocation techniques based on eigen mode, Newton and convex optimization method and carrier-interference-and-noise ratio (CINR) are proposed to improve link reliability and to increase throughput with reasonable computational complexity. The proposed scheme is evaluated by Monte-Carlo simulations and is shown to outperform the conventional power allocation scheme.展开更多
基金supported by the National Major Specific Project of Oil and Gas during the Twelfth Five-Year Plan (2011ZX05028-004)the Major Science and Technology Program of Petro China (2012D-4602-05)the National Natural Science Foundation of China (61501064)
文摘Symbols are considered as the language of a map;hence,accurate understanding of the meaning of symbols is crucial when obtaining geographical information from a map： the symbolisation of spatial data is of key importance in cartography.A geographical information system（GIS） provides a convenient mapping platform and powerful functions for spatial data symbolisation,while the presence of various mapping standards impedes the understanding of maps and sharing of map information.On the other hand,the available GIS platforms find it difficult to deal with automatic conversion between maps and different mapping standards.To resolve this problem,an approach for symbol recognition and automatic conversion is proposed,and a conversion system based on the approach and the Arc GIS Engine platform is developed to realise automatic conversion between maps produced based on different mapping standards.To test these conversion effects of the proposed system,the petroleum sector is chosen as the research field and the mutual conversion of a map in practical work among the three mapping standards（i.e.the Chinese Petroleum,Shell and USGS standards） governing this field is taken as a casestudy.The results show that the conversion system has a high conversion accuracy and strong applicability.
基金supported by the National Natural Science Foundation of China(NSFC.NO.61303253)
文摘Feedforward symbol timing recovery techniques are particularly important for initial acquisition in burst modems. However, these techniques either have large calculation burden or sensitive to frequency offsets. In this paper, we proposed an efficient symbol timing recovery algorithm of MPSK signals named OMQ(Ordered Maximum power using Quadratic approximation partially) algorithm which is based on the Quadratic Approximation(QA) algorithm. We used ordered statistic sorting method to reduce the computational complexity further, meanwhile maximum mean power principle was used to decrease frequency offset sensitivity. The proposed algorithm adopts estimation-down sampling structure which is suitable for small packet size transmission. The results show that, while comparing with the QA algorithm, the computational complexity is reduced by 75% at most when 8 samples per symbol are used. The proposed algorithm shows better performance in terms of the jitter variance and sensitivity to frequency offsets.
基金supported by the National Basic Research Program of China (973 Program) (2010CB731803)the National Science Foundation for Innovative Research Groups of China (60921001)
文摘The symbol-error-rate（SER） and power allocation for hybrid cooperative（HC） transmission system are investigated.Closed-form SER expression is derived by using the moment generating function（MGF）-based approach.However,the resultant SER contains an MGF of the harmonic mean of two independent random variables（RVs）,which is not tractable in SER analysis.We present a simple MGF expression of the harmonic mean of two independent RVs which avoids the hypergeometric functions used commonly in previous studies.Using the simple MGF,closed-form SER for HC system with M-ary phase shift keying（M-PSK） signals is provided.Further,an approximation as well as an upper bound of the SER is presented.It is shown that the SER approximation is asymptotically tight.Based on the tight SER approximation,the power allocation of the HC system is investigated.It is shown that the optimal power allocation does not depend on the fading parameters of the source-destination（SD） channel and it only depends on the source-relay（SR） and relay-destination（RD） channels.Moreover,the performance gain of the power allocation depends on the ratio of the channel quality between RD and SR.With the increase of this ratio,more performance gain can be acquired.
文摘There is a big demand for increasing number of subscribers in the fourth generation mobile communication systems. However, the system performance is limited by multi-path propagations and lack of efficient power allocation algorithms in conventional wireless communication systems. Optimal resource allocation and interference cancellation issues are critical for the improvement of system performance such as throughput and transmission reliability. In this paper, a turbo coded bell lab space time system (TBLAST) with optimal power allocation techniques based on eigen mode, Newton and convex optimization method and carrier-interference-and-noise ratio (CINR) are proposed to improve link reliability and to increase throughput with reasonable computational complexity. The proposed scheme is evaluated by Monte-Carlo simulations and is shown to outperform the conventional power allocation scheme.
