CONCEPTUALIZATION AND ANALYSIS OF USING UNMANNED AERIAL VEHICLES AS COMMUNICATIONS RELAYS IN A GPS-DENIED ENVIRONMENT

Many armed forces are becoming network-centric and highly interconnected. This transformation, along with decentralized decision-making, has been enabled by technological advancements in the digital battlefield. As the battlefield evolves and missions require units to be mobile and support numerous tactical capabilities, the current concept of deploying static radio-relay nodes to extend the range of communication may no longer be suitable. Hence, this thesis aims to design an operational concept using unmanned aerial systems such as aerostats and tactical drones to provide beyond line-of-sight communication for tactical forces while overcoming the limitations in a GPS-denied environment. The proposed concept is divided into three phases to assess operational and communication system needs, given Federal Communications Commission regulations that set the maximum effective isotropic radiated power in the industrial, scientific, and medical band at 36 dBm. The maximum communication range between two nodes can be studied using the Friis propagation equation. In addition, Simulink software is used to study the effective application throughput with respect to distance. From the analysis, IEEE 802.11ax can provide a higher data throughput and support both 2.4 GHz and 5.0 GHz frequency bands. Using a simulated environment and operational scenario, the estimated number of aerial systems required to provide communication coverage for a 50 km by 50 km area is determined.Captain, Singapore ArmyApproved for public release. Distribution is unlimited

Cooperative performance bounds of Wireless Local Area Networks

In a Wireless Local Area Network (WLAN), capacity gain and delay reduction play a crucial role in system performance. In this paper, we focus on performance improvements when WLANs exploit the concept of cooperation among nodes. We propose a geometrical model to determine the potential location area of relay nodes. The analytical results are validated by simulation. Performance bounds and average of capacity gain and delay ratio are studied for different IEEE 802.11 standards

Multi-Antenna Assisted Virtual Full-Duplex Relaying with Reliability-Aware Iterative Decoding

In this paper, a multi-antenna assisted virtual full-duplex (FD) relaying with reliability-aware iterative decoding at destination node is proposed to improve system spectral efficiency and reliability. This scheme enables two half-duplex relay nodes, mimicked as FD relaying, to alternatively serve as transmitter and receiver to relay their decoded data signals regardless the decoding errors, meanwhile, cancel the inter-relay interference with QR-decomposition. Then, by deploying the reliability-aware iterative detection/decoding process, destination node can efficiently mitigate inter-frame interference and error propagation effect at the same time. Simulation results show that, without extra cost of time delay and signalling overhead, our proposed scheme outperforms the conventional selective decode-and-forward (S-DF) relaying schemes, such as cyclic redundancy check based S-DF relaying and threshold based S-DF relaying, by up to 8 dB in terms of bit-error-rate.Comment: 6 pages, 4 figures, conference paper has been submitte

Relay Technologies in IEEE 802.16j Mobile Multi-hop Relay (MMR) Networks

IEEE 802.16 standard is created to compete with cable access networks. In the beginning end users are immobile and have a line of sight with base station, now it moved to mobile non line of sight (NLOS) with the new standard IEEE 802.16e and IEEE 802.16j. The new IEEE 802.16j standard which is an amendment to IEEE 802.16e is mobile multi hop relay (MMR) specification for wireless networks. This paper discusses relay modes, relay transmission schemes and relay pairing schemes of IEEE 802.16j. Relay technologies such as transparent relay modes, non transparent relay mode, relay pairing schemes such as centralized relay pairing schemes, distributed relay pairing scheme, characterises of relay based networks such as throughput enhancement, capacity increase, cost reduction , relay techniques such as time domain frequency domain relay techniques and relay placement are also discussed in this paper. The paper also discusses about integration of IEEE 802.16j with IEEE 802.11. Keywords: IEEE 802.16j, Relay pairing schemes, relay techniques, Relay modes, WIMAX, NCTUns, et

State-of-the-art in Power Line Communications: from the Applications to the Medium

In recent decades, power line communication has attracted considerable attention from the research community and industry, as well as from regulatory and standardization bodies. In this article we provide an overview of both narrowband and broadband systems, covering potential applications, regulatory and standardization efforts and recent research advancements in channel characterization, physical layer performance, medium access and higher layer specifications and evaluations. We also identify areas of current and further study that will enable the continued success of power line communication technology.Comment: 19 pages, 12 figures. Accepted for publication, IEEE Journal on Selected Areas in Communications. Special Issue on Power Line Communications and its Integration with the Networking Ecosystem. 201