Enabling rural broadband via TV "white space"

The use of multiple frequency bands within a wireless network allows the advantages of each band to be exploited. In this paper we discuss how HopScotch, a rural wireless broadband access test bed running in the Scottish Highlands and Islands, uses both 5 GHz and ultra high frequency "white space" bands to offer large data rates and expansive coverage whilst reducing the number of base stations or required transmission power. This reduction in energy consumption allows HopScotch to provide a low-cost and green solution for rural broadband delivery

The Importance of Human Motion for Simulation Testing of GNSS

Human motion is generally considered benign to the performance of global navigation satellite system (GNSS) and other positioning sensors. This study proves that this is not the case, even for typical human behaviour involving GNSS user equipment, e.g. in smartphones. Using recorded human motion, it is shown that phase-lock loops (PLLs) in GNSS receivers are sensitive to jerk dynamics induced by user motion, resulting in carrier cycle slips. To test the effects of human dynamics on GNSS carrier tracking, real human motion profiles were captured. These profiles comprised typical types of movements using a mobile phone, e.g. holding, answering and texting, different types of activities, e.g. walking or jogging, as well as different phone locations on the human body, e.g. in a hand, pocket, backpack and on an arm band. The data were captured outdoors using an Xsens MTi-G MEMS (Micro-Electronic Mechanical Systems) Inertial Measurement Unit (IMU) aided by a Global Positioning System (GPS) receiver with a 100Hz output rate. Then the captured motion (MoCap) was processed and input into a simulated PLL in Matlab with different tracking loop bandwidths (BL_CA) and carrier power-to-noise density ratios (C/N0). The results show that pedestrian gestures and type of activity, e.g. walking or jogging, affect the performance of the simulated PLL more adversely than the location of the phone on the human body. Also, to track pedestrian motion encompassing these gestures, activities and receiver locations, a minimum of 15Hz tracking bandwidth is required. Consequently, receiver manufacturers should exercise caution before reducing tracking bandwidths to compensate for the reduction in C/N0 resulting from GNSS antenna design, human body masking and the effects of buildings, trees and other environmental features. This paper also proposes and describes a pedestrian motion model (PMM) that simulates the GNSS antenna trajectory in 3D, when it is held by or attached to a pedestrian. The PMM will be validated using real MoCap scenarios and will enable Spirent to increase their product offering in the area of simulation-based testing of positioning sensors for pedestrian applications by generating human motion profiles which affect realistically the performance of GNSS user equipment

A sensitivity analysis method for evaluating the effect of input parameter uncertainty on the results of the PALM model system

Within the scope of this work, a sensitivity analysis method for input parameters of numerical models is developed and applied to the PALM model system. For an application of PALM in urban areas, input data concerning land use, surfaces, soil type, buildings and vegetation are required. They can be obtained from various sources like municipal data, Open Street Map, satellite data or aerial imagery. However, quality and availability of input data are very heterogeneous, which results in uncertainties in the input parameters, which are transferred to the model results. In the presented study, the quality of the input parameters is investigated with respect to the required accuracy of the model results. A systematic sensitivity analysis based on the Morris method an a OAT sensitivity study is carried out for the input parameters required for PALM simulations of the urban environment. This allows for the selection of the input parameters, for which extensive data acquisition is worthwhile and necessary for obtaining reliable model results with a suffcient accuracy. In addition, conclusions are drawn on possible methods for the adaptation of urban areas to climate change based on the results of the sensitivity analysis discussing quantities with a large impact on the air temperature and the UTCI

Temporal video transcoding from H.264/AVC-to-SVC for digital TV broadcasting

Mobile digital TV environments demand flexible video compression like scalable video coding (SVC) because of varying bandwidths and devices. Since existing infrastructures highly rely on H.264/AVC video compression, network providers could adapt the current H.264/AVC encoded video to SVC. This adaptation needs to be done efficiently to reduce processing power and operational cost. This paper proposes two techniques to convert an H.264/AVC bitstream in Baseline (P-pictures based) and Main Profile (B-pictures based) without scalability to a scalable bitstream with temporal scalability as part of a framework for low-complexity video adaptation for digital TV broadcasting. Our approaches are based on accelerating the interprediction, focusing on reducing the coding complexity of mode decision and motion estimation tasks of the encoder stage by using information available after the H. 264/AVC decoding stage. The results show that when our techniques are applied, the complexity is reduced by 98 % while maintaining coding efficiency