【作者】 孙锦华；

【导师】 李建东；

【作者基本信息】 西安电子科技大学 ， 通信与信息系统， 2007， 博士

【摘要】 在军事通信领域,窄带高速数据传输技术是提高频谱利用率、传输速率和系统容量及系统抗干扰能力的关键技术。其中主要包括先进的高效编码调制技术、链路自适应技术等。这些技术对于构建战术互联网和数据链提供了强有力的传输平台。本文主要研究了跳频系统中低复杂度的连续相位调制传输技术。本文的主要研究内容和成果如下:1.将分数多比特差分检测器FMDD进行推广,从相位形成的物理意义对FMDD的实质进行解释,并对达到最大性能增益的分数比特区间上限进行了理论分析。分析与仿真结果说明:通过将多个分数比特差分输出合并,改善了信噪比,从而获得性能增益;当分数比特区间达到不影响码元判决的最大区间时,可以获得最大的性能增益。2.提出了一种适用于跳频系统的低复杂度的非相干RSDSD检测器。通过合理的状态合并,简化后的检测器与最佳ML检测相比,在欧氏距离上不带来性能损失或仅带来较小的性能损失。另外接收端不需要知道确切的载波初始相位,对于跳频系统和时变信道具有较好的适应性,并且也能够容忍一定程度的频差,更适合于载波恢复困难的情况。3.设计了“新一代超短波窄带高速数传电台”的CPM调制解调器波形参数,并在系统样机中实现了非相干的RSDSD检测算法,进行了调制解调器的性能测试、整机的灵敏度测试和远距离通信实验,大大提升了上一代通信装备的数据传输能力。4.研究了一种基于判决引导相位同步的CPM准相干解调算法。该算法仅付出较小的开销就可以进一步改善跳频系统下非相干CPM检测的功率利用率,特别适合于快跳频系统中一跳数据量较少的情况。5.研究了SCCPM系统的误比特率联合界和系统设计准则。对于不同参数的SCCPM系统,在频谱利用率相同的条件下,权衡误比特率的上限和实现复杂度,找出性能较好的系统参数。6.对于SCCPM系统低复杂度的迭代解码器,提出了一种基于RSSD的简化状态SISO迭代译码算法。该算法避免了基于Laurent分解的简化译码算法的局限性,基于状态截短的减化状态SISO算法是该算法的特例。在运算复杂度相同的情况下,基于RSSD的简化状态SISO解码器可以得到比状态截短SISO解码器更小的性能损失。7.研究了采用非线性连续相位调制CPM的自适应跳频通信系统的信道质量估计问题,提出了一种基于信号平均相位距离的盲信道质量检测算法。该算法无需训练码元,采用盲估计,运算量小,特别适用于快跳频系统中一跳数据量较少的情况。对于常见的跳频干扰,该算法可以有效地进行信道质量的评估。更多还原

【Abstract】 In military communication field, narrowband high speed data transmission technique is the key to improve the bandwidth efficiency, transmission rate, system capacity and the ability to combact interference. There includes more advanced high efficiency code and modulation technique, link adaptation technique and etc..These techniques provide powerful transmission platform for constructing tactical internet and data link. In this dissertation, the low complexity continuous phase modulation transmission technique is studied.The main research works and results are listed as follows:1. The fractional multi-bit differential detector is generalized. The essential of the technique is explained from the physical meaning of phase forming, and theoretical analysis to the upper bound of the fractional bit duration for the maximum performance improvement is given. Analysis and simulation results show that the signal-to-noise ratio is improved. Performance gain is obtained by combining multiple fractional multi-bit differential detector outputs. When the fractional bit duration is the maximal duration in which the symbol decision is not influenced, the maximum performance gain can be achieved.2. A noncoherent RSDSD detector with low complexity for frequency hopping system is proposed. By reasonably choosing state fusing, the reduced detector has no or little degradation in the Euclidean distance compared with the optimum ML detector. Also the exact initial carrier phase need not to be known in the receiver, which is more appropriate to the frequency hopping system and time varying channel. The detector is tolerable to frequency offset within some range and more robust to the situation when the carrier recovery is difficult.3. The CPM modem waveform parameters are designed for the New Generation VHF Narrowband High Speed Data Transmission Radio. The noncoherent RSDSD algorithm is implemented in the experimental system radio. The performance of the modem and the sensitivity of the radio are tested. The far distance communication experiment is made. The results show that the transmission ability of the last negeration equipment is upgraded.4. A quasi-coherent demodulation algorithm based on the direct decision phase synchrionization is studied. The algorithm can further improve the power efficiency of noncoherent CPM detection for frequency hopping system only at little cost. It is more appropriate to the fast frequency hopping system when there is little data in one hop frame.5. The bit error rate union bound and system design criteria of SCCPM system are studied. For SCCPM system with different parameters, the tradeoff between bit error rate union bound and implementation complexity should be consided at the same bandwidth efficiency, and system parameters with good performance should be found.6. For the low complexity iterative decoder of SCCPM system, a reduced state SISO iterative decoding algorithm based on RSSD is proposed. The algorithm avoids the limit of the reduced decoding algorithms based on Laurent decomposition, and the reduced state SISO algorithm based on state truncation is also a special case of the proposed algorithm. At the same computation complexity, the reduced state SISO algorithm based on RSSD provides even little performance loss compared with the SISO decoder based on state truncation.7. The channel quality estimation for adaptive frequency hopping system using nonlinear continuous phase modulation is studied, and a blind channel quality estimation algorithm based on the average signal phase distance is proposed. The algorithm is blind estimation without training symbols and with low complexity, which is appropriate to the fast frequency hopping system when there is little data in one hop frame. For usual frequency hopping interference, the algorithm can efficiently evaluate the channel quality.更多还原