Channel Estimation/Tracking In Unique-Word Based Single-Carrier Frequency-Domain Equalization Systems

Mobile communication systems have undergone significant growth since the introduction of the first-generation cellular networks. Meanwhile, third-generation (3G) technologies have been widely employed in markets. Although 3G systems have achieved advances over second-generation but 3GPP-LTE technology (3rd Generation Partnership Project Long Term Evolution) has drawn much attention. LTE is beyond 3G systems and it's mainly a development to 3G UMTS (Universal Mobile Telecommunication System) toward 4G systems. Different expected requirements from LTE were determined by 3GPP. Among these requirements are: high data rate, low latency and flexible spectrum allocation. To meet such requirements, two main physical layer technologies have been adopted. Orthogonal frequency division multiple access (OFDM) is used in downlink, and single carrier frequency division multiple access (SC-FDMA) has been adopted in uplink. The structure of SC-FDMA and OFDMA has much in common; hence, SC-FDMA is sometimes called DFT-precoded OFDMA. The choice of SC-FDMA in uplink was fuelled by its low peak-to-average power ratio (PAPR). This implies the simplicity of user equipment (UE) which is the utmost concern for LTE.SC-FDMA is viewed as an extension to single carrier system with frequency domain equalization (SC-FDE). SC-FDE systems are basically designed for broadband wireless communications to mitigate the frequency selective channels. The equalization process in SC-FDE is carried out in frequency domain. The idea beyond frequency domain equalization is to maintain circularity of transmitted signal blocks. To meet this requirement, either cyclic prefix (CP) or unique word (UW) is used. In SC-FDE/UW which is the core of our thesis, a known sequence is appended to each transmitted signal block. In this thesis, we are investigating and developing some techniques that can exploit the previous knowledge of UW to estimate/track the frequency-selective channel. We've proposed an adaptive method that consists of existing algorithms which showed good results under different mobility.