GMSK linearization and structured channel estimate for GSM signals
GMSK linearization and structured channel estimate for GSM signals
复制标题
GSM 信号的 GMSK 线性化和结构化信道估计
DOI：
10.1109/milcom.1997.646733
复制
发表时间：
1997
期刊：
影响因子：
--
通讯作者：
A. Paulraj
中科院分区：
文献类型：
--
作者：
Jen;B. Ng;J.;A. Paulraj
GMSK是一种频谱效率高的调制方式，它被采用作为GSM系统的调制标准。然而，由于其相位调制、高斯滤波和部分响应信令特性，GMSK不是线性调制。本文给出了T/2分数间隔下GMSK信号的线性近似。具有3个符号周期的记忆长度的部分响应信道（其是GMSK调制中固有的脉冲成形函数）可以在该线性近似中清楚地识别。进一步地，我们将这些部分响应信道信息用于无线信道的估计，其中包括物理传播信道和调制脉冲成形函数。传统的信道估计器，例如，相关器或最小二乘估计器方法不利用已知和可用的脉冲整形函数的信息。我们提出的结构化信道估计是更准确的，因为我们将信道结构的知识在估计过程中。我们比较了GSM系统的误比特率（BER）性能与结构化和非结构化的信道估计，仿真结果表明，在不同的测试信道时，使用结构化的信道估计的Viterbi均衡器的改善。
GMSK is a spectrum-efficient modulation scheme, and it is adopted as the modulation standard of GSM systems. However, because of its phase modulation, Gaussian filtering, and partial response signaling properties, GMSK is not a linear modulation. We present a linear approximation of GMSK signals at T/2 fractional spacing. The partial response channel with a memory length of 3 symbol periods, which is the pulse-shaping function inherent in the GMSK modulation, can be clearly identified in this linear approximation. Further more, we use this partial response channel information in the estimation of the wireless channel, which includes the physical propagation channel and the modulation pulse-shaping function. Conventional channel estimators, e.g., correlator or least-squares estimator approaches, do not exploit the information of the pulse-shaping function which is known and available. Our proposed structured channel estimate is more accurate since we incorporate the knowledge of the channel structure in the estimation procedure. We compared the BER (bit-error-probability) performance of a GSM system with the structured and unstructured channel estimate, and simulation results show the improvement of a Viterbi equalizer in different test channels when a structured channel estimate is used.