This paper presents a high efficiency spread spectrum scheme using approximate orthogonal complex (AOC) sequences. In this scheme, the 64 AOC sequences picked up from 84 complex sequences space are employed for spread...This paper presents a high efficiency spread spectrum scheme using approximate orthogonal complex (AOC) sequences. In this scheme, the 64 AOC sequences picked up from 84 complex sequences space are employed for spreading spectrum. In modulation, 6 input bits is used to select one AOC sequence, and the selected sequence is then phase-rotated by another 2 input bits. In demodulator, a complex correlator detects the transmitted AOC sequence. Simulation results show that the proposed scheme has better BER performance than the existing complementary code keying (CCK) modulation scheme. For AOC, additional processing gain of 1.79dB can be obtained when the sequence length is 8.展开更多
This paper presents a novel scheme of high efficiency spreading spectrum modulation using double orthogonal complex sequences(DoCS).In this scheme,input data bit-stream is split into many groups with length M.Each gro...This paper presents a novel scheme of high efficiency spreading spectrum modulation using double orthogonal complex sequences(DoCS).In this scheme,input data bit-stream is split into many groups with length M.Each group is then mapped into a word of width M and then utilized to select one sequence from 2M-2 DoCS sequences each with length L.After that,the selected sequence is modulated on carrier in quadrature phase shift keying(QPSK) mode.In addition,a new method named forward phase correction(FPC) is put forward for carrier recovery.Theoretical analysis and bit-error-ratio(BER) experiment results indicate that the proposed scheme has better performance than the conventional direct sequence spread spectrum(DSSS) scheme both in bandwidth efficiency and processing gain of the receiver.展开更多
A dual N-ary orthogonal hybrid modulation system is introduced in this paper,which can increasethe data rate greatly compared with conventional N-ary orthogonal spread spectrum system,so it can beused for high rate da...A dual N-ary orthogonal hybrid modulation system is introduced in this paper,which can increasethe data rate greatly compared with conventional N-ary orthogonal spread spectrum system,so it can beused for high rate data communication.Then,three code recognition algorithms are presented for dual N-ary orthogonal hybrid modulation system and the analytic bit error rate(BER)performance of the systemin additive white Gaussian noise(AWGN)and flat Rayleigh fading channel is derived.Finally,the com-puter simulation of the system with three code recognition algorithms is performed,which shows that thesimplified maximum a posteriori(MAP)algorithm is the best for the system with a compromise betweenthe performance and the complexity.展开更多
This paper analyzes the performance of both in-band and outband narrowband interference suppression in orthogonal code modulation spread spectrum system, and compares with conventional spread spectrum system at the sa...This paper analyzes the performance of both in-band and outband narrowband interference suppression in orthogonal code modulation spread spectrum system, and compares with conventional spread spectrum system at the same information transmission rate and spread spectrum bandwidth. Simulation results indicate that the antijamming (narrowband interference) performance obtained from orthogonal code modulation spread spectrum system is much better than that from conventional spread spectrum system.展开更多
在水声通信中,扩频通信具有可靠性高、抗多径能力强等特点,适合于远程或低信噪比情况下的通信;但另一方面,由于其带宽利用率低加之水声信道带宽有限,通信系统的数据率将受到很大的限制。为了提高数据率,提出了一种正交M-ary/DS扩频方法...在水声通信中,扩频通信具有可靠性高、抗多径能力强等特点,适合于远程或低信噪比情况下的通信;但另一方面,由于其带宽利用率低加之水声信道带宽有限,通信系统的数据率将受到很大的限制。为了提高数据率,提出了一种正交M-ary/DS扩频方法,该方法将正交直接序列(DS)扩频与并行M-ary扩频结合在一起,能够显著提高水声通信系统的数据率与带宽利用率。经过湖上实验验证,该方法在25 km距离约0 dB的接收信噪比下,采用63、127长度G o ld序列并通过RAKE接收,分别实现了对480个符号的无误码传输,数据率为381.0 b its/s与220.5 b its/s,其带宽利用率与使用相同序列的直接序列扩频相比提高了约一个数量级。展开更多
针对常规直接序列扩频水声通信数据传输速率低及M元扩频水声通信接收机复杂度高的问题,提出了一种正交频分复用(orthogonal frequency division multiplexing,OFDM)技术和循环移位键控(cyclic shift keying,CSK)技术相结合的调制方式,...针对常规直接序列扩频水声通信数据传输速率低及M元扩频水声通信接收机复杂度高的问题,提出了一种正交频分复用(orthogonal frequency division multiplexing,OFDM)技术和循环移位键控(cyclic shift keying,CSK)技术相结合的调制方式,该调制能很大程度地提高系统的带宽使用率。从理论上对该方法在高斯白噪声信道条件下的误码率进行了分析。同时,采用Chu序列作为扩频序列,通过理论推导得出其峰均功率比(peak to average power ratio,PAPR)的上限为3dB。利用实际湖试测量得到的多径信道模型,与DSSS-OFDM方法进行了误码率性能的分析比较。结果表明,新提出的方法具有很好的抗多径性能,且具有带宽利用率高、复杂度低的特点,适用于中、远程及多用户水声通信。展开更多
文摘This paper presents a high efficiency spread spectrum scheme using approximate orthogonal complex (AOC) sequences. In this scheme, the 64 AOC sequences picked up from 84 complex sequences space are employed for spreading spectrum. In modulation, 6 input bits is used to select one AOC sequence, and the selected sequence is then phase-rotated by another 2 input bits. In demodulator, a complex correlator detects the transmitted AOC sequence. Simulation results show that the proposed scheme has better BER performance than the existing complementary code keying (CCK) modulation scheme. For AOC, additional processing gain of 1.79dB can be obtained when the sequence length is 8.
基金Union Innovation Found of Jiangsu Province(No. BY2009149)
文摘This paper presents a novel scheme of high efficiency spreading spectrum modulation using double orthogonal complex sequences(DoCS).In this scheme,input data bit-stream is split into many groups with length M.Each group is then mapped into a word of width M and then utilized to select one sequence from 2M-2 DoCS sequences each with length L.After that,the selected sequence is modulated on carrier in quadrature phase shift keying(QPSK) mode.In addition,a new method named forward phase correction(FPC) is put forward for carrier recovery.Theoretical analysis and bit-error-ratio(BER) experiment results indicate that the proposed scheme has better performance than the conventional direct sequence spread spectrum(DSSS) scheme both in bandwidth efficiency and processing gain of the receiver.
基金the National Basic Research Program of China(No5130601)Jiangsu Provincial Natural Science Foundation(NoBK2006701)
文摘A dual N-ary orthogonal hybrid modulation system is introduced in this paper,which can increasethe data rate greatly compared with conventional N-ary orthogonal spread spectrum system,so it can beused for high rate data communication.Then,three code recognition algorithms are presented for dual N-ary orthogonal hybrid modulation system and the analytic bit error rate(BER)performance of the systemin additive white Gaussian noise(AWGN)and flat Rayleigh fading channel is derived.Finally,the com-puter simulation of the system with three code recognition algorithms is performed,which shows that thesimplified maximum a posteriori(MAP)algorithm is the best for the system with a compromise betweenthe performance and the complexity.
文摘This paper analyzes the performance of both in-band and outband narrowband interference suppression in orthogonal code modulation spread spectrum system, and compares with conventional spread spectrum system at the same information transmission rate and spread spectrum bandwidth. Simulation results indicate that the antijamming (narrowband interference) performance obtained from orthogonal code modulation spread spectrum system is much better than that from conventional spread spectrum system.
文摘在水声通信中,扩频通信具有可靠性高、抗多径能力强等特点,适合于远程或低信噪比情况下的通信;但另一方面,由于其带宽利用率低加之水声信道带宽有限,通信系统的数据率将受到很大的限制。为了提高数据率,提出了一种正交M-ary/DS扩频方法,该方法将正交直接序列(DS)扩频与并行M-ary扩频结合在一起,能够显著提高水声通信系统的数据率与带宽利用率。经过湖上实验验证,该方法在25 km距离约0 dB的接收信噪比下,采用63、127长度G o ld序列并通过RAKE接收,分别实现了对480个符号的无误码传输,数据率为381.0 b its/s与220.5 b its/s,其带宽利用率与使用相同序列的直接序列扩频相比提高了约一个数量级。
文摘针对常规直接序列扩频水声通信数据传输速率低及M元扩频水声通信接收机复杂度高的问题,提出了一种正交频分复用(orthogonal frequency division multiplexing,OFDM)技术和循环移位键控(cyclic shift keying,CSK)技术相结合的调制方式,该调制能很大程度地提高系统的带宽使用率。从理论上对该方法在高斯白噪声信道条件下的误码率进行了分析。同时,采用Chu序列作为扩频序列,通过理论推导得出其峰均功率比(peak to average power ratio,PAPR)的上限为3dB。利用实际湖试测量得到的多径信道模型,与DSSS-OFDM方法进行了误码率性能的分析比较。结果表明,新提出的方法具有很好的抗多径性能,且具有带宽利用率高、复杂度低的特点,适用于中、远程及多用户水声通信。
