A new design method interleavers, 2-dimension interleavers, are proposed for interleave division multiple access （IDMA） systems. With a same interleaving rule named I＇, the row indices and column indices of a tradi...A new design method interleavers, 2-dimension interleavers, are proposed for interleave division multiple access （IDMA） systems. With a same interleaving rule named I＇, the row indices and column indices of a traditional block interleaving matrix are scrambled to obtain an interleaver, which is marked as the master interleaver. F is produced by a loworder PN sequence generator. Two ways are provided for generating different interleavers. One is that all interleavers are generated by the circular shifting master interleaver. The other is that different inter leavers are generated by different Ts. Besides, we prove that the minimum distance between two adjacent bits resulted from 2-dimension interleaves is much larger than that of other schemes, such as random interleavers, power interleavers, and shiffting interleaves. The simulation results show that 2-dimension interleavers can achieve much better performance with much less resource consumption than random interleavers in IDMA systems.展开更多
In this paper, a hybrid orthogonal and random multiple access scheme with improved performance for capacity-enhanced downlink Code-Division Multiple-Access (CDMA) systems is presented, which is in fact a combination o...In this paper, a hybrid orthogonal and random multiple access scheme with improved performance for capacity-enhanced downlink Code-Division Multiple-Access (CDMA) systems is presented, which is in fact a combination of the conventional orthogonal spreading scheme and the synchronous Interleave Division Multiple Access (IDMA) scheme. The proposed scheme can achieve near single user performance for very large number of users by the iterative turbo like detection. Analysis and simulation results show that the proposed scheme performs better than the synchronous IDMA scheme for the same time complexity. Meanwhile, larger capacity can be provided compared with the conventional orthogonal schemes.展开更多
High spectral efficiency is essential in design of multimedia communication systems such as L-band mobile in addition to various requirements of transmission quality.Time-interleaved A/D converter(TI-ADC)is an effecti...High spectral efficiency is essential in design of multimedia communication systems such as L-band mobile in addition to various requirements of transmission quality.Time-interleaved A/D converter(TI-ADC)is an effective candidate to implement wide-band ADC with relatively slow circuits accounting for digital spectrum management.However,practical performance of TI-ADC is largely limited because of mismatches between different channels originated from manufacturing process variations.In this paper,a blind adaptive method is proposed to correct gain mismatch errors in TI-ADC,and it is verified through simulations on a two-channel TI-ADC.In proposed method,gain mismatch error is estimated and corrected in an adaptive scheme.Proposed compensated TI-ADC architecture is structurally very simple and hence suitable for realization in integrated circuits.Besides,proposed digital compensation algorithm not only is computationally efficient but also provides an improvement of 32.7 dB in the performance of two-channel TI-ADC.展开更多
基金supported by the National Key Lab. Research Foundation of China under Grant No.2007CB310604
文摘A new design method interleavers, 2-dimension interleavers, are proposed for interleave division multiple access （IDMA） systems. With a same interleaving rule named I＇, the row indices and column indices of a traditional block interleaving matrix are scrambled to obtain an interleaver, which is marked as the master interleaver. F is produced by a loworder PN sequence generator. Two ways are provided for generating different interleavers. One is that all interleavers are generated by the circular shifting master interleaver. The other is that different inter leavers are generated by different Ts. Besides, we prove that the minimum distance between two adjacent bits resulted from 2-dimension interleaves is much larger than that of other schemes, such as random interleavers, power interleavers, and shiffting interleaves. The simulation results show that 2-dimension interleavers can achieve much better performance with much less resource consumption than random interleavers in IDMA systems.
基金Supported by the National Natural Science Foundation of China (No.60402017/90604035)the Sichuan Youth Science Foundation (No.05ZQ026-026).
文摘In this paper, a hybrid orthogonal and random multiple access scheme with improved performance for capacity-enhanced downlink Code-Division Multiple-Access (CDMA) systems is presented, which is in fact a combination of the conventional orthogonal spreading scheme and the synchronous Interleave Division Multiple Access (IDMA) scheme. The proposed scheme can achieve near single user performance for very large number of users by the iterative turbo like detection. Analysis and simulation results show that the proposed scheme performs better than the synchronous IDMA scheme for the same time complexity. Meanwhile, larger capacity can be provided compared with the conventional orthogonal schemes.
基金Project supported by the"863"National High-Tech Research and Development Program of China(No.2008AA01 Z211)the International Science and Technology Cooperation Program(No.2008DFA11630)
基金Iran’s Telecommunication Research Center(ITRC)(No.500/3653)
文摘High spectral efficiency is essential in design of multimedia communication systems such as L-band mobile in addition to various requirements of transmission quality.Time-interleaved A/D converter(TI-ADC)is an effective candidate to implement wide-band ADC with relatively slow circuits accounting for digital spectrum management.However,practical performance of TI-ADC is largely limited because of mismatches between different channels originated from manufacturing process variations.In this paper,a blind adaptive method is proposed to correct gain mismatch errors in TI-ADC,and it is verified through simulations on a two-channel TI-ADC.In proposed method,gain mismatch error is estimated and corrected in an adaptive scheme.Proposed compensated TI-ADC architecture is structurally very simple and hence suitable for realization in integrated circuits.Besides,proposed digital compensation algorithm not only is computationally efficient but also provides an improvement of 32.7 dB in the performance of two-channel TI-ADC.
