Robust synchronization for PSK (DVB-S2) and OFDM systems

The advent of high data rate (broadband) applications and user mobility into modern wireless communications presents new challenges for synchronization in digital receivers. These include low operating signal-to-noise ratios, wideband channel effects, Doppler effects and local oscillator instabilities. In this thesis, we investigate robust synchronization for DVB-S2 (Digital Video Broadcasting via Satellite) and OFDM (Orthogonal Frequency Division Multiplexing) systems, as these technologies are well-suited for the provision of broadband services in the satellite and terrestrial channels respectively.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Improved Preamble-Aided Timing Estimation for OFDM Systems

Abstract-An improved method for estimating the frame/symbol timing offset in preamble-aided OFDM systems is presented. It uses a conventional preamble structure and combines autocorrelation techniques with restricted crosscorrelation to achieve a near-ideal timing performance without significant increase in complexity. Computer simulations show that the method is robust in both AWGN and fading multipath channels, achieving better performance than the existing methods

Spectrally Efficient Waveforms for the Return Link in Satellite Communication Systems

In this paper, we study the applicability of terrestrial mobile waveforms in the return link of a high throughput satellite (HTS) communication system. These include orthogonal frequency division multiple access (OFDMA), single-carrier frequency division multiple access (SC-FDMA) and filter bank multi-carrier (FBMC). Key solutions to the challenges in a geostationary orbit (GEO) satellite channel, such as synchronization and non-linear distortion, are presented. A global-positioning-system-(GPS)-based approach for synchronization acquisition is proposed, while suitable algorithms are studied for timing/frequency offset estimation and synchronization tracking. The spectral and power efficiencies of the schemes are optimized by means of an intermodulation interference (IMI) cancelling receiver, and these are compared to state-of-the-art time division multiple access (TDMA). Finally, end-to-end simulations validate the system performance

Robust synchronization for PSK (DVB-S2) and OFDM systems.

The advent of high data rate (broadband) applications and user mobility into modern wireless communications presents new challenges for synchronization in digital receivers. These include low operating signal-to-noise ratios, wideband channel effects, Doppler effects and local oscillator instabilities. In this thesis, we investigate robust synchronization for DVB-S2 (Digital Video Broadcasting via Satellite) and OFDM (Orthogonal Frequency Division Multiplexing) systems, as these technologies are well-suited for the provision of broadband services in the satellite and terrestrial channels respectively. DVB-S2 systems have a stringent frequency synchronization accuracy requirement and are expected to tolerate large carrier frequency offsets. Consequently, the existing techniques make use of a coarse acquisition and a fine-tracking stage. However, the use of two stages introduces extra synchronization delays. Therefore, we propose an improved technique for DVB-S2 frequency synchronization based on a novel method also proposed for single frequency estimation. The proposed method is single-stage, feed-forward, of practical complexity and has a wide estimation range. Consequently, a significant reduction in synchronization delays and a wider estimation range is achievable for DVB-S2 fixed and mobile systems. On the other hand, OFDM systems are quite sensitive to symbol timing offsets and very sensitive to earner frequency offsets due to orthogonality requirements. The existing techniques for timing and frequency synchronization suffer from various drawbacks in terms of overhead efficiency, computational complexity, accuracy and estimation range. Therefore, in this thesis, we propose two novel low-complexity techniques for timing and time-frequency synchronization in OFDM respectively. Both use only one training symbol with a simple and conventional structure to achieve a similar bit-error-rate (BER) performance to that of an ideal synchronized system and also a wide frequency estimation range. The improvement achieved translates into reduced overhead, higher power efficiency, lower hardware costs and higher reliability in OFDM receivers

Capacity Enhancing Techniques for High Throughput Satellite Communications

In this paper, we present physical layer and system level techniques that can increase the capacity of a multi-beam high throughput satellite (HTS) communication system. These include advanced predistortion and equalization techniques for the forward link, synchronization and non-linear distortion minimization techniques for the return link waveforms. Interference management techniques such as precoding, multi-user detection (MUD), interference cancellation and coordination are evaluated under realistic co-channel interference (CCI) conditions. Interference-aware radio resource management (RRM) algorithms are presented for the forward and return links with full frequency reuse. These include satellite-switched smart gateway diversity, interference aware scheduling (IAS) for the forward link and scheduling based on multi-partite graph matching for the return link. The capacity enhancing techniques are evaluated in the Broadband Access via Integrated Terrestrial and Satellite Systems (BATS) framework