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针对海洋中无法设立传统基站对舰船通信进行辅助的问题,提出了mesh结构下的跳频正交频分复用系统。为了提高通信时的同步检测概率和系统误码性能,提出了快速有效的同步和信道估计算法。基于IEEE802.16d-2004标准,提出了改进的前导码结构。使用了GPS秒脉冲来修正的系统参考时钟,将时钟频率漂移由30 ppm降至0.01 ppm。给出了海面舰船移动通信时的频率时间双选择性衰落信道模型,并基于该模型提出了基于互相关函数和自相关函数联合判定的定时同步方法,通过峰值的判定可以将同步偏差控制在10个采样周期以内。使用了计算量较小的导频辅助线性插值信道估计算法,保证了接收节点能够快速的计算出有效的信道估计值。仿真结果表明所提出的定时同步和信道估计算法可以在60 km/h的移动速度下满足系统的定时同步和误码率要求。
In view of the problem that the traditional base station can not be established in the ocean to assist the ship communication, a frequency hopping orthogonal frequency division multiplexing system under the mesh structure is proposed. In order to improve the synchronization detection probability and system error performance during communication, a fast and effective synchronization and channel estimation algorithm is proposed. Based on the IEEE802.16d-2004 standard, an improved preamble structure is proposed. A system reference clock, modified with GPS seconds, reduces the clock frequency drift from 30 ppm to 0.01 ppm. The frequency-time dual-selective fading channel model is proposed for the mobile communications of the surface ships. Based on this model, a timing synchronization method based on the cross-correlation function and the autocorrelation function joint judgment is proposed. The synchronization error can be controlled by Within 10 sampling periods. The pilot-assisted linear interpolation channel estimation algorithm with less computation is used to ensure that the receiving node can quickly calculate the effective channel estimation value. The simulation results show that the proposed timing synchronization and channel estimation algorithms can meet the system timing synchronization and bit error rate requirements at a moving speed of 60 km / h.