一种应用CPM扩频调制的Turbo CDMA系统

本文首先介绍了连续相位调制CPM (Continuous Phase Modulation) 的分解模型^[1],得到CPM调制可以分解为一个线性连续相位编码CPE (Continuous Phase Encoder)和无记忆调制的组合;接着基于CPM的错误事件和递归特性,推出了采用CPM扩频调制的Turbo CDMA系统模型,这里CPM扩频调制作为递归内码,与外编码器及交织器级连构成Turbo迭代系统,该系统有明显的交织增益.利用系统的迭代解调解扩和解码的特点,设计了软输入输出的接收机,接收机中解调器采用MAP(Maximum A Posterior)和SOVA(Soft Output Viterbi Algorithm)算法,解码器采用MAP算法.仿真结果表明CPM调制器作为内码形成级连迭代系统交织增益非常明显.     

Reduced phase-state detection based on virtual modulation indexes for Multi-h CPM

.Simplified detection with reduced phase-state based on virtual modulation indexes was designed for Multi-h CPM.Multiple sets of modulation indexes different from the transmitter were constructed in the receiver,and the per-survivor processing was used to solve the mismatch caused by the inconsistency of the modulation indexes between the receiver and the transmitter.When the denominator of virtual modulation index was much smaller than the original denominator of actual transmitted signal,the phase states of coherent sequence detection could be effectively simplified,thus the complexity of coherent detection for Multi-h CPM could be reduced.The trellis could be simplified further via combining with the frequency pulse truncation(FPT) used for simplifying correlation states.The simulation results show that for advanced range telemetry (ARTM) CPM signal,various simplified receiving schemes based on virtual modulation indexes can be designed.When the virtual modulation indexes are set to $\left[\frac{\text{3}}{\text{4}}\text{,}\frac{\text{2}}{\text{4}}\right]$,the number of trellis states can be reduced from 512 (in optimal detection) to 64,but the performance loss is less than 0.05 dB.Further combined with FPT algorithm,the number of trellis states can be reduced to 16,while the performance loss is only 0.75 dB.     

基于FABA-SISO的时变频率选择性衰落信道CPM信号盲均衡

该文针对时变频率选择性衰落信道下高阶连续相位调制(CPM)信号盲均衡中存在的均衡性能较差、复杂度较高以及收敛速度慢等问题,从双向自适应信道均衡的角度出发,将线性调制信号均衡中使用的前后向自适应软输入软输出(FABA-SISO)算法推广,建立一种新的基于FABA-SISO的信道盲均衡方法,并结合逐幸存处理(PSP)思想和Kalman滤波,提出一种适用于高阶CPM信号的自适应盲均衡算法。该算法通过使用FABA-SISO算法,同时利用过去、现在和将来的观察数据进行Kalman滤波信道估计,有效改善了信道估计的精度,同时使用PSP算法来降低系统的复杂度,使得算法具有较好的工程应用性。仿真结果表明所提算法具有良好的盲均衡性能以及收敛性。     

过采样CPM信号的频域均衡

提出了一种直接对过采样的连续相位调制(CPM)信号进行单载波频域均衡的算法,同时提出了一种在插入循环前缀后发送CPM信号的相位仍然连续的方法。仿真结果表明,该单载波频域均衡算法能有效地消除大时延信道冲击响应下的CPM接收信号中的码间串扰。与现有的基于匹配滤波、符号抽样的CPM信号的单载波频域均衡算法相比,其性能和复杂度相当,但是CPM接收机的前端更为简单。     

一种CPM信号频率成形脉冲盲估计算法

频率成形脉冲是连续相位调制(CPM)信号解调所必需的调制参数,由脉冲形状和脉冲长度两个参数共同决定。该文利用CPM信号的自相关特性,深入分析了CPM信号调制参数与自相关函数之间的内在联系,并在此基础上提出了一种频率成形脉冲的盲估计算法。该算法首先实现脉冲形状的盲识别,然后将CPM信号的调制指数调整为整数,最后通过自相关函数中非零值的个数来实现脉冲长度的盲估计。计算机仿真结果与分析表明,该算法实现简单,能够在任意调制阶数和调制指数下有效估计出频率成形脉冲。     

物理层网络编码中连续相位调制信号的非相干多符号检测

基于连续相位调制(CPM)的物理层网络编码(PNC)由于其高效的吞吐率和频谱利用率特性引起了越来越多的关注。现有关于CPM-PNC检测的研究大多建立在到达中继端的两节点信号载波相位完全同步或相位差已知的基础上。实际应用中,这一载波相位差不可避免,也很难准确估计。针对这一问题,该文提出一种中继端存在未知载波相位差条件下的CPM-PNC非相干多符号检测算法。该算法根据最大似然检测原理,通过观察多个码元来实现中间码元的检测,充分利用了CPM信号的相位记忆特性。仿真结果表明,该文所提出的CPM-PNC非相干多符号检测算法性能优越。而且随着观察窗口长度的增大,其性能显著提高并逐渐趋近最优相干检测性能。在误码率(BER)为10-4 时,相比于非相干单符号检测,观察窗口长度为5个码元时的CPM-PNC非相干多符号检测有6.7 dB的性能增益。     

A Novel Serially Concatenated GMSK System for Satellite Communications

A novel serially concatenated GMSK system is proposed for satellite communications subject to low SNR, limited power and spectrum resources. First, we design a Nonrecursive continuous-phase encoder (NRCPE) based GMSK based on the Rimoldi's decomposition. Then, a corresponding pilot-aided quasi-coherent demodulation algorithm is developed, whose basic principle is that a modified BCJR-based detection performs on the received signals with initial and ending trellisstates being determined using the very limited pilot overhead. Finally, we choose proper modulation parameters for the NRCPE based Gaussian minimum shift keying GMSK signaling according to the trade-offs between the power and spectral efficiency. The simulation results show that the LDPC coded GMSK system using the proposed algorithm can achieve excellent performance and can also work well in the presence of the large Doppler shifts and some burst errors.     

CPM的减少状态非相干序列检测算法

连续相位调制(CPM)本身所具有的高功率和频谱利用率特性使得它在无线通信领域尤其是军事通信领域中应用广泛,但其解调的复杂度也随着部分响应长度和进制数的增加呈指数增长.文章给出了一种CPM的减少状态非相干序列检测算法,通过正交化处理有效地减少了匹配滤波器个数;在序列检测阶段,通过状态融合减少维特比译码的状态数,然后结合判决反馈进行检测.     

采用混合染料饱和吸收体获得33fs激光脉冲

本文介绍采用DODCI和Malachite green(MG)混合染料作为饱和吸收体,在CPM染料激光器中获得33fs脉冲的结果。     

碰撞锁模多量子阱半导体激光器模式锁定过程的物理模型

提出了碰撞锁模多量子阱激光器模式锁定过程的完整的物理模型，该模型全面地考虑了吸收体的饱和吸收效应和瞬态光栅效应及增益区端面附近和靠近吸收体处的瞬态光栅作用。作为应用实例采用本模型研究了多量子阱结构激光器的模式锁定过程及瞬态光栅对脉冲半峰宽及峰值功率的影响。