3 research outputs found
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
A Cross Layer Routing Protocol for OFDMA Based Mobile Ad Hoc Networks.
PhDMobile ad hoc networks are of growing interest because of their unique characteristics
and advantages in many practical applications. QoS provision acts as a major challenge
in the routing protocol design in the real-world mobile ad hoc networks, especially for
the real-time services. OFDM is a new technology which has many advantages over the
other modulation schemes. Because of its prominent features, many popular wireless
standards have adopted it as physical layer modulation, such as IEEE 802.11 series,
WiMAX, 3GPP LTE etc, and it is extended to multiuser environment known as OFDMA.
So far none of the existing ad hoc routing protocols fully account for the OFDMA based
mobile ad hoc networks. In this thesis, a QoS routing protocol is proposed for OFDMA
based mobile ad hoc networks. A signal strength-based sub-channel allocation scheme is
proposed in the routing protocol aiming to reduce the signalling overhead and cochannel
interference. The performance of the proposed routing protocol is compared
with other alternative proposals through simulations using OPNET simulator. Moreover,
a partial time synchronization and a null subcarrier based frequency synchronization
algorithms are also proposed for OFDMA based ad hoc network to further support and
facilitate the proposed sub-channel allocation scheme and routing protocol