Performance of an Echo Canceller and Channel Estimator for On-Channel Repeaters in DVB-T/H Networks

This paper investigates the design and performance of an FIR echo canceller for on-channel repeaters in DVB-T/H network within the framework of the PLUTO project. The possible approaches for echo cancellation are briefly reviewed and the main guidelines for the design of such systems are presented. The main system parameters are discussed. The performance of an FIR echo canceller based on an open loop feedforward approach for channel estimation is tested for different radio channel conditions and for different number of taps of the FIR filter. It is shown that a minimum number of taps is recommended to achieve a certain mean rejection ratio or isolation depending on the type of channel. The expected degradation in performance due to the use of fixed point rather than floating point arithmetic in hardware implementation is presented for different number of bits. Channel estimation based on training sequences is investigated. The performance of Maximum Length Sequences and Constant Amplitude Zero Autocorrelation (CAZAC) Sequences is compared for different channels. Recommendations are given for training sequence type, length and level for DVB-T/H on-channel repeater deployment

An Adaptive Feedback Interference Cancellation Algorithm for Digital On-channel Repeaters in DTTB Networks

Abstract-In this paper, a variable step-size block normalized least mean square (VSSBNLMS) algorithm is derived to cancel the feedback interference in a Digital On-Channel Repeater (DOCR) for the Digital Terrestrial Television Broadcasting (DTTB) networks. By dividing the input signal into blocks with the same length and updating the tap weights once per every block, the computational complexity can be decreased effectively. Furthermore, variable step-size is applied to increase the convergence speed. Compared with the NLMS and BLMS algorithm, VSSBNLMS algorithm achieves rapid convergence and the computational complexity is reduced compared to the NLMS algorithm. Results from numerical examples illustrate these advantages. Keywords-variable step-size block normalized LMS (VSSBNLMS) algorithm, Digital Terrestrial Television Broadcasting (DTTB), digital on-channel repeater (DOCR), feedback interference canceller (FIC

Potentzia domeinuko NOMA 5G sareetarako eta haratago

Tesis inglés 268 p. -- Tesis euskera 274 p.During the last decade, the amount of data carried over wireless networks has grown exponentially. Several reasons have led to this situation, but the most influential ones are the massive deployment of devices connected to the network and the constant evolution in the services offered. In this context, 5G targets the correct implementation of every application integrated into the use cases. Nevertheless, the biggest challenge to make ITU-R defined cases (eMBB, URLLC and mMTC) a reality is the improvement in spectral efficiency. Therefore, in this thesis, a combination of two mechanisms is proposed to improve spectral efficiency: Non-Orthogonal Multiple Access (NOMA) techniques and Radio Resource Management (RRM) schemes. Specifically, NOMA transmits simultaneously several layered data flows so that the whole bandwidth is used throughout the entire time to deliver more than one service simultaneously. Then, RRM schemes provide efficient management and distribution of radio resources among network users. Although NOMA techniques and RRM schemes can be very advantageous in all use cases, this thesis focuses on making contributions in eMBB and URLLC environments and proposing solutions to communications that are expected to be relevant in 6G