Low-Complexity Digital Modem Design and Implementation for High-Speed Aerial Backbones
- Publication Type:
- Thesis
- Issue Date:
- 2019
Open Access
Copyright Clearance Process
- Recently Added
- In Progress
- Open Access
This item is open access.
Wireless communication technology is moving towards the integration of terrestrial networks with space networks. However, a number of grand technological challenges have to be overcome for such integration. This thesis addresses some of these challenges and develops efficient and effective solutions to successfully achieve a high-speed aerial backbone link.
The first challenge is the signal synchronization in presence of large carrier frequency offset (CFO). In this thesis, new methods for preamble-aided coarse timing estimation are investigated. Integrated with simple auto-correlation operation, CFO can be estimated and compensated for better frame synchronization in high-speed aerial backbone links. Moreover, the optimized algorithms can be implemented with low-complexity. Simulation result shows that the proposed method can capture tens of Mega Hertz CFO with rapid convergence.
The In-phase and Quadrature-phase (I/Q) imbalance is another significant factor which impacts on practical wideband wireless backbone systems. An effective algorithm is proposed to estimate I/Q imbalance with specially designed training sequence. After I/Q imbalance estimation, I/Q imbalance compensation is combined with channel equalization as well as sampling rate conversion to form the receiver filters of the system. Simulation result shows that the estimated receiver and transmitter imbalance coefficients are quite close to the true values and the joint algorithm can achieve the desired performance.
Analog-to-digital and digital-to-analog conversion devices for signals with very large bandwidth are not always available due to technical or cost issues. In this thesis, a dual pulse shaping (DPS) transmission scheme is proposed, which can achieve full Nyquist rate transmission with only a half of the sampling rate for each of the two data streams. The condition for cross-symbol interference free transmission is derived and validated for two classes of ideal complementary Nyquist pulses. Structures of the DPS transmitter and receiver are described and low-complexity equalization techniques tailored to DPS are provided as well. The simulation results with two sets of practical dual spectral shaping pulses verify the effectiveness of the proposed scheme.
Finally, the design and implementation of a high-speed low-complexity digital modem for wireless communications at 0.325 terahertz (THz) are presented. The requirements, architecture and signal processing modules of the system are described. Some key strategies are applied to ensure the proposed low complexity algorithms can be implemented in real-time field-programmable gate array (FPGA) platform. The digital modem implementation and the integrations with IF modules and RF frontend are described and the experimental results of them are provided.
Please use this identifier to cite or link to this item: