CN107317774B - 一种ccsk解调预处理方法 - Google Patents
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- H—ELECTRICITY
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Abstract
本发明属于通信技术领域,尤其涉及一种CCSK解调预处理方法。本发明从正常CCSK调制信号能量分布均匀,而畸变后的信号能量分布不均出发,用限幅的方法约束信道均衡之后信号的能量分布范围,使得CCSK解调性能有较大提升。本发明的方法不要求慢衰落的信道环境,相比现有技术,应用场景更加多样、普遍。
Description
技术领域
本发明属于通信技术领域,尤其涉及一种CCSK解调预处理方法。
背景技术
循环码移键控(Cyclic Code Shift Keying,CCSK)调制通过降低数据率来换取误码率性能的增益,具有很强的抗噪声和抗干扰能力。文献“Addressing the controlchannel design problem:OFDM-based transform domain communication system incognitive radio”(Chuan Han,Jun Wang,Shaoqian Li.Elsevier Computer NetworksJournal.2008,52(4):795-815)将OFDM技术与CCSK技术相结合,提出一种基于正交频分复用的变换域通信系统。这种通信系统能够在极低信噪比、以及子载波部分可用和收发机子载波使用不一致的情况下保证可靠的传输性能,并且,由于采用了多载波技术提高了系统的抗衰落能力。
但是在实际应用中,通信系统加入信道估计模块之后,在低信噪比情况下信道估计误差会非常大,信道均衡过程也由此给信号引入强烈畸变,使传输性能大大降低。此时采用最小二乘法得到的信道系数可表示为:其中,H[k]为理论信道系数,W[k]为信道噪声产生的估计误差。在极低信噪比下,误差能量可能远大于理论信道系数的能量,此时估计的信道系数可以近似为只有误差部分。在H[k]+W[k]≈0时,均衡接收信号会造成严重的信号畸变。
针对上述问题,文献“变换域通信系统中的信道估计技术”(王军,李少谦,龚树平,韩川.电子科技大学学报,2009,38(1):40-42)利用慢衰落信道环境下信道系数变化缓慢的特点,提出了时间滑动平均、时间遗忘、时间滑动平均与时间遗忘结合等几种解决方法。但是这几种方法要求慢衰落的信道环境。而上文提到的通信系统正是为了能够在各种复杂信道环境下正常通信而设计,因此需要其他能够适应多种不同场景的方法解决信号畸变导致系统传输性能下降的问题。
发明内容
本发明从正常CCSK调制信号能量分布均匀,而畸变后的信号能量分布不均出发,用限幅的方法约束信道均衡之后信号的能量分布范围,使得CCSK解调性能有较大提升。本发明的方法不要求慢衰落的信道环境,相比现有技术,应用场景更加多样、普遍。
一种CCSK解调预处理方法,具体步骤如下:
S1、初始化,具体为:
S11、设置通信系统OFDM的符号X(k)的长度为N,其中,k=0,1,2,3,...,N-1,
S12、设置CCSK的调制阶数为Mary,其中,Mary的取值为2的幂次方,且2≤Mary≤N,
S13、设置空闲频谱标记向量A=[A0,A1,...Ar,...AN-1],若Ar的元素值为1则表示该频点对应子载波可用,若Ar的元素值为0则表示该频点对应子载波不可用,其中,r=0,1,2,3,...,N-1,
S14、生成CCSK频域基函数B=[B0,B1,...Bk,...BN-1],其中,表示CCSK频域基函数B中的第k个元素,每个发送符号在时域上总功率为Es,NT为可用子载波个数,mk∈{0,1,...N-1}为伪随机整数,
S15、设置限幅门限T0,其中,T0为经验值;
S2、生成经过CCSK调制的OFDM信号并发射;
本发明的有益效果是:
本发明方法克服了以时间平均为核心的算法在应用场景方面的限制,能够在普遍的场景下,有效处理CCSK信号在信道均衡中出现畸变的情况,获得明显的性能提升。
附图说明
图1为本发明方法流程图。
图2为CCSK性能仿真结果。
具体实施方式
下面结合附图对本发明进行说明。
实施例、
采用Matlab2014b仿真平台进行运行实验,其中,仿真参数为:信源为每10个比特转换成1个十进制整数的数据Si,OFDM符号的循环前缀长度设为128,窗函数采用汉明窗,信号通过高斯信道。
如图1所示,一种CCSK解调预处理方法,具体步骤如下:
步骤1:初始化
1.1设置通信系统OFDM的符号长度为N=1024。
1.2设置CCSK的调制阶数为Mary=1024。
1.3设置空闲频谱标记向量A,A8~A472,A553~A1016为可用子载波,其余为不可用子载波。
1.4时域总功率Es=1,伪随机整数mk是由一个10级线性反馈移位寄存器生成。
1.5设置多个限幅门限T0=[0.5,1,1.5,2],此处设置多个限幅门限方便最终进行性能对比。
步骤2:生成经过CCSK调制的OFDM信号并发射。
4.2进行CCSK解调,并对多个限幅门限的结果进行性能对比。
按照所述参数仿真2e7次,在相同条件下,得到本发明与未进行预处理的CCSK性能对比如图2所示,对比指标为误比特率。
Claims (1)
1.一种CCSK解调预处理方法,其特征在于,具体步骤如下:
S1、初始化,具体为:
S11、设置通信系统OFDM的符号X(k)的长度为N,其中,k=0,1,2,3,...,N-1,
S12、设置CCSK的调制阶数为Mary,其中,Mary的取值为2的幂次方,且2≤Mary≤N,
S13、设置空闲频谱标记向量A=[A0,A1,...Ar,...AN-1],若Ar的元素值为1则表示该频点对应子载波可用,若Ar的元素值为0则表示该频点对应子载波不可用,其中,r=0,1,2,3,...,N-1,
S14、生成CCSK频域基函数B=[B0,B1,...Bk,...BN-1],其中,表示CCSK频域基函数B中的第k个元素,每个发送符号在时域上总功率为Es,NT为可用子载波个数,mk∈{0,1,...N-1}为伪随机整数,
S15、设置限幅门限T0,其中,T0为经验值;
S2、生成经过CCSK调制的OFDM信号并发射;
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Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4707839A (en) * | 1983-09-26 | 1987-11-17 | Harris Corporation | Spread spectrum correlator for recovering CCSK data from a PN spread MSK waveform |
KR101026141B1 (ko) * | 2010-11-18 | 2011-04-06 | 삼성탈레스 주식회사 | 순환 부호 천이 키잉 복조 시 부분 상호 상관을 수행하는 fhss/tdma 수신 장치 및 방법 |
CN102340478A (zh) * | 2011-07-21 | 2012-02-01 | 电子科技大学 | 一种变换域通信系统及其发送信号产生方法 |
CN106453185A (zh) * | 2016-08-31 | 2017-02-22 | 电子科技大学 | 一种基于ccsk调制的idma系统改进方法 |
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Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4707839A (en) * | 1983-09-26 | 1987-11-17 | Harris Corporation | Spread spectrum correlator for recovering CCSK data from a PN spread MSK waveform |
KR101026141B1 (ko) * | 2010-11-18 | 2011-04-06 | 삼성탈레스 주식회사 | 순환 부호 천이 키잉 복조 시 부분 상호 상관을 수행하는 fhss/tdma 수신 장치 및 방법 |
CN102340478A (zh) * | 2011-07-21 | 2012-02-01 | 电子科技大学 | 一种变换域通信系统及其发送信号产生方法 |
CN106453185A (zh) * | 2016-08-31 | 2017-02-22 | 电子科技大学 | 一种基于ccsk调制的idma系统改进方法 |
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