Title: Optical Wireless Communications: Current approaches and future directions
Future communications networks will require extremely high data rate wireless connectivity in order to allow users to access the bandwidth that will be available from an all-optical fixed core network. The spectrum ‘crunch’ means that this is unlikely to be met using RF approaches at carrier frequencies that provide good coverage, as has been traditionally been the case. Optical wireless, both at visible and infrared wavelengths, has the potential to access hundreds of THz of spectrum, using devices that are potentially low cost. In this presentation different approaches to providing access will be described, together with some of the fundamental challenges for the optical wireless channel. Finally, future directions, and potential architectures for an all-optical approach to communications will be described.
Title: Shining light on LiFi
We will start by clarifying the differences between visible light communications (VLC) and LiFi. This is followed by the introduction of the key building blocks required to create full LiFi networks. Next we report recent key achievements of the UP-VLC project with respect to component and demonstrator developments underpinning LiFi atto- cellular networks. We provide modelling results of such networks and address numerous misconceptions such as ”LiFi is a line-of-sight technology”. The talk also addresses the issue of energy efficiency of optical attocell networks and showcases how off-the-shelf solar panels can fulfil two functions at the same time, i) energy harvesting and ii) LiFi data detection. The talk closes by summarizing commercialization challenges.
Title: Wireless Avionics Intra-aircraft Communications (WAIC) for Commercial Aircraft
Wireless Avionics Intra-Communications (WAIC) systems will liberate aircraft safety service interconnections from tethered wiring, offering designers and operators opportunities to improve flight safety, reliability, and operational efficiency. By reducing the overall system weight, wireless provides fuel reduction and subsequent environmental benefits, supporting more cost-effective flight operations. WAIC also supports reduced complexity of aircraft design and manufacture, lowers maintenance costs, and yields greater flexibility to enhance aircraft systems that maintain or increase the level of safety, thereby improving an aircraft’s performance over its useful lifetime. The AVSI WAIC team worked with various national administrations over the past 7 years to establish an Agenda Item (AI 1.17) at the World Radio Conference 2012 (WRC-12), and then provided thorough analyses and proof of non-interference co-existence through the ITU-R Working Party 5B to successfully obtain an allocation of dedicated spectrum for WAIC in the candidate 4200-4400 MHz band at WRC-15 under this Agenda Item. The 4200-4400 MHz band was exclusively reserved for radar altimeter applications prior to this allocation. Under AVSI project AFE 76 – WAIC Protocols, detailed network and hardware architectures, protocols, requirements, and appropriate protection criteria for spectrum sharing are being defined to protect WAIC and legacy altimeter systems from interfering with each other. WAIC applications have been categorized as either Low Rate (< 10kbits/sec data transmit rate) or High Rate (>10 kbits/sec), each having some unique SWaP, cost, and performance requirements. AFE 76 is now addressing more detailed design issues, including: system boundaries where WAIC standards might be applied; plans for WAIC spectrum assignments to ensure efficient usage; channel allocation and channel spacing scheme for WAIC systems; methods for achieving coexistence between WAIC systems installed on different aircraft; and a road map for working with international regulatory and standards organizations to ultimately implement WAIC components and systems.
The world’s failed and increasingly and rapidly unraveling Energy, Economics (& Environmental (EEE) policies have been desperately subsidizing “all of the above” energy alternatives. Stated more correctly, these have been any energy alternative except one that would provide a real energy alternative to fossil fuels(oil, gas and coal). This is unsurprising, since fossil energy is the most profitable industry on planet Earth. SSP’s compelling EEE features, however, will not only greatly surpass the analytical features of our existing energy industry, but provide huge numbers of excellent jobs leading to commercialization of the entire cis-lunar space (Earth to Moon neighborhood).
For an economic example, the Space Solar Power Institute does not yet have a space transportation working group, but we pledged $10,000. to help sponsor a continuing conference where interested space transportation companies (there are a half dozen now working that challenge) would come and join in bringing into focus the low cost space transportation necessary for global SSP system construction. Currently our diverse communications satellite industry is a $333 Billion dollar industry. Since we expect to launch a thousand times more vehicles to orbit per year after an SSP system begins construction, this might suggest that SSP would become a $333 Trillion dollar industry. SSP would obviously take some time to meet and surpass that bar, when we become serious about this EEE basket, or bouquet, of problems. That’s a lot of jobs. Retraining and redirecting our coal mining industry, for example, to become Moon miners and SSP construction and parts manufacturers will require a lot of hands and hearts.
Title: Design and development of avionic sensors and systems for Wireless Avionics Intra-Communications (WAIC)
The introduction of wireless avionic sensors and systems to the commercial aerospace industry will play an integral role in the development of next generation aircraft. In particular, the Wireless Avionics Intra-Communications (WAIC) Project, under the Aerospace Vehicle Systems Institute (AVSI) AFE-76, aims to develop design methodologies, protocol requirements and other relevant wireless networking recommendations to ensure the reality of wireless avionics for safety-related applications on commercial aircraft. WAIC will have applicability in areas such as engine sensors, environmental control systems, and structural health monitoring, which are envisioned to be designed as both passive and active systems. The benefits of these wireless systems include, but are not limited to, the overall reduction of aircraft wiring (weight and cost savings), mitigation of single-point failures and lower frequency of maintenance. WAIC was allocated a frequency band of 4.2 to 4.4 GHz at the WRC-15 under ITU Agenda Item (1.17), and therefore must give precedence and coexist with radio altimeters onboard the aircraft. Work is currently being carried out to explore coexistence scenarios and interference avoidance techniques between WAIC and the radio altimeters. Experimental flight tests at NASA’s Armstrong Flight Research Center will be carried out in order to provide insight on WAIC coexistence and interference scenarios; the results of which will serve as a design tool for commercial wireless avionics development to abide by radio altimeter protection and coexistence criteria for the successful deployment of WAIC systems on aircraft.
Title: Connectivity of Asymmetric Sensor Networks
In this presentation, connectivity of an asymmetric network represented by a weighted directed graph is investigated. The notion of weighted vertex connectivity is introduced as a metric to evaluate the connectivity of a random sensor network where the elements of the weight matrix characterize the operational probability of their corresponding communication links. The weighted vertex connectivity measure extends the notion of vertex connectivity to weighted graphs by taking into account the joint effects of path reliability and network robustness to node failure. The problem of finding the weighted vertex connectivity measure is transformed into a sequence of iterative deepening depth-first search and maximum weight clique problems, and based on that, an algorithm is developed to find the proposed connectivity metric. The approximate weighted vertex connectivity measure is defined subsequently as a lower bound on the introduced connectivity metric which can be found by applying a series of a polynomial-time shortest path algorithm. The notion of generalized algebraic connectivity is also introduced as an extension of the algebraic connectivity to weighted directed graphs. This measure reflects the expected asymptotic convergence rate of cooperative algorithms used to control the network. This connectivity measure is then described in terms of the eigenvalues of the Laplacian matrix of the digraph representing the network. The advantage of this new metric over the algebraic connectivity measure in describing the connectivity of asymmetric networks is demonstrated using some counter-intuitive examples. The generalized power iteration algorithm is then developed to compute the proposed connectivity measure in a distributed fashion. The performance of the proposed algorithm is validated using an experimental underwater acoustic sensor network.