ScholarBank@NUShttps://scholarbank.nus.edu.sgThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Thu, 27 Jan 2022 21:42:07 GMT2022-01-27T21:42:07Z5051- Performance analysis of a homodyne receiver in modulated backscattered system for intelligent transportationhttps://scholarbank.nus.edu.sg/handle/10635/50588Title: Performance analysis of a homodyne receiver in modulated backscattered system for intelligent transportation
Authors: Marath, Ashok Kumar; Chia, Yan Wah Michael; Ko, Chi Chung
Abstract: Radio frequency transponders are finding increasing applications in intelligent transportation for automatic transactions. Low system cost is one major concern. Modulated backscattering is one such concept, which is attractive in terms of price and simplicity. This paper looks at the major system level issues in the implementation and possible solutions. Based on our study, the scattering from nearby moving objects and carrier leakage are some of the key parameters limiting the sensitivity of the system. An homodyne system was evaluated using behavioural model based on discrete time domain, found in HP EESOF, a commercial CAD. Selection of suitable coding with proper filtering is found to be a possible solution for problems due to scattering from moving objects. Our results also show that the front end low noise amplifier does not provide any improvement in system sensitivity in systems where carrier leakage is the dominant mechanism limiting the sensitivity. Possible solutions are also discussed.
Fri, 01 Jan 1999 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/505881999-01-01T00:00:00Z
- Efficient scheme for DOA estimation of multipath clusters in WiMedia UWB systemshttps://scholarbank.nus.edu.sg/handle/10635/70115Title: Efficient scheme for DOA estimation of multipath clusters in WiMedia UWB systems
Authors: Marath, A.K.; Leyman, A.R.; Garg, H.K.
Abstract: UWB systems are expected to find widespread use in future short range applications. Increasing popularity of these devices will require management of occupied spectrum in spatial domain to keep the interference low. In Ultra Wide Band (UWB) communication systems, one encounters many multipath components. By optimally forming beams in the direction of the principal multipath clusters, one can achieve optimum spectrum efficiency. The number of components would depend on the sampling rate as the number of resolvable components depends on it. Besides, many of the multipath components would be coming from the same cluster. The estimation of the Direction of Arrival (DOA) of these clusters is very useful to focus the transmit power in the optimum direction. A new algorithm, exploiting the known pilot signals of multiband UWB systems for estimation of DOA of clusters is proposed recently. By making use of a new matrix incorporating the cross correlation between the focused UWB signal and the known pilot signal of the transmitted data in each array element, one would be able to separate the multipath clusters from a single source. This paper looks at reducing the number of receivers required for implementing the algorithm. UWB System makes use of the preample to synchronize the incoming data. Hence, one can employ a central processor to sample the data from individual sensors in a time multiplexed fashion. This time multiplexed sampled data can be used for finding the expected value of correlation with known reference data. This would allow usage of fewer receivers to achieve the same level of performance. Computer experiments are included to verify the performance of the proposed algorithm with and without receiver time multiplexing.
Tue, 01 Jan 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/701152008-01-01T00:00:00Z
- Performance analysis of a homodyne receiver in modulated backscattered system for intelligent transportationhttps://scholarbank.nus.edu.sg/handle/10635/80945Title: Performance analysis of a homodyne receiver in modulated backscattered system for intelligent transportation
Authors: Marath, Ashok Kumar; Chia, Yan Wah Michael; Ko, Chi Chung
Abstract: Radio frequency transponders are finding increasing applications in intelligent transportation for automatic transactions. Low system cost is one major concern. Modulated backscattering is one such concept, which is attractive in terms of price and simplicity. This paper looks at the major system level issues in the implementation and possible solutions. Based on our study, the scattering from nearby moving objects and carrier leakage are some of the key parameters limiting the sensitivity of the system. An homodyne system was evaluated using behavioural model based on discrete time domain, found in HP EESOF, a commercial CAD. Selection of suitable coding with proper filtering is found to be a possible solution for problems due to scattering from moving objects. Our results also show that the front end low noise amplifier does not provide any improvement in system sensitivity in systems where carrier leakage is the dominant mechanism limiting the sensitivity. Possible solutions are also discussed.
Fri, 01 Jan 1999 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/809451999-01-01T00:00:00Z
- New focusing scheme for DOA estimation of multipath clusters in WiMedia UWB systems without coarse estimation of angle of arrivalhttps://scholarbank.nus.edu.sg/handle/10635/56798Title: New focusing scheme for DOA estimation of multipath clusters in WiMedia UWB systems without coarse estimation of angle of arrival
Authors: Marath, A.K.; Leyman, A.R.; Garg, H.K.
Abstract: Ultra wideband (UWB) systems are expected to coexist with narrowband systems as well as other UWB systems. By estimating the direction of arrival of the multipaths, one would be able to limit the transmission to these directions and limit the interference to other systems. The focussing of subspaces is used to improve the resolution performance in direction of arrival estimation of wideband signals. The focussing matrix is calculated based on initial coarse estimation of DOA. The error in initial estimation results in an irreducible bias in final estimated DOA. By making use of the known pilot signals in Wimedia systems, a new focussing scheme is proposed in this paper that does not require coarse estimation. Computer simulation experiments validating this scheme are also presented. The bias in final estimation is drastically reduced. © 2010 IEEE.
Mon, 01 Feb 2010 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/567982010-02-01T00:00:00Z
- DOA estimation of multipath clusters in WiMedia UWB systemshttps://scholarbank.nus.edu.sg/handle/10635/51151Title: DOA estimation of multipath clusters in WiMedia UWB systems
Authors: Marath, A.K.; Leyman, A.R.; Garg, H.K.
Abstract: Ultra Wide Band (UWB) systems are expected to find widespread use in future short range applications. Increasing popularity of these devices will require management of occupied spectrum in spatial domain to keep the interference low. In UWB systems, one encounters many multipath components. By optimally forming beams in the direction of the principal multipath clusters, one can achieve optimum spectrum efficiency. The number of components would depend on the sampling rate as the number of resolvable components depends on it. Besides, many of the multipath components would be coming from the same cluster. The estimation of the Direction of Arrival (DOA) of these clusters is very useful to focus the transmit power in the optimum direction. A new algorithm, exploiting the known pilot signals of multiband UWB systems for estimation of DOA of clusters in the presence of inband interferers is proposed in this paper. By making use of a new matrix Incorporating the cross correlation between the focused UWB signal and the known pilot signal of the transmitted data in each array element, one would be able to separate the multipath clusters from a single source. It is proven that the proposed new matrix would span the same subspace as the direction of arrival vectors and the eigen vectors corresponding to the zero eigen value of the product of this new matrix with its Hermitian would span the orthogonal compliment of the DOA subspace. Computer experiments are included to verify the performance of the proposed algorithm. © 2008 IEEE.
Tue, 01 Jan 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/511512008-01-01T00:00:00Z