Global Positioning System (GPS) localization has been attracting attention recently in various areas, including intelligent transportation systems (ITSs), navigation systems, road tolling, smart parking, and collision avoidance. Although, various approaches for improving localization accuracy have been reported in the literature, there is still a need for more efficient and more effective measures that can ascribe some level of accuracy to the localization process. These measures will enable localization systems to manage the localization process and resources to achieve the highest accuracy possible and to mitigate the impact of inadequate accuracy on the target application. The localization accuracy of any GPS system depends heavily on both the technique it uses to compute locations and the measurement conditions in its surroundings. However, while localization techniques have recently started to demonstrate significant improvement in localization performance, they continue to be severely impacted by the measurement conditions in their environment. Indeed, the impact of the measurement conditions on the localization accuracy in itself is an ill-conditioned problem due to the incongruent nature of the measurement process. This paper proposes a scheme to address localization accuracy estimation. This scheme involves two steps, namely, measurement condition disambiguation and enhanced location accuracy classification. Real-life comparative experiments are presented to demonstrate the efficacy of the proposed scheme in classifying GPS localization accuracy under various measurement conditions.

The efficiency by which a node of a vehicular ad hoc network (VANET) can route messages to destinations heavily depends on the VANET's ability to keep track of the locations of its nodes (vehicles). Current location-management schemes lack scalability and, hence, are proven unable to work in large-scale networks. Therefore, location management in VANETs remains a major challenge. In this paper, we propose a new region-based location-service-management protocol (RLSMP) that uses mobility patterns as means to synthesize node movement and, thus, can be used in large VANET applications. The protocol attempts to relax the scalability issue suffered by other protocols by employing message aggregation in location updating and in querying. Furthermore, due to the protocol's intrinsic locality awareness, it achieves minimum control overhead. To evaluate the efficiency of the protocol, we study its performance analytically and by using simulation for a 2-D random-walk model, as well as on real mobility patterns. The performance of the protocol is compared with that of other prominent location-management protocols.

A wideband circularly polarized L-shaped monopole slot antenna with a single C-shaped feed is designed and fabricated. The measured results demonstrate that the antenna has an axial ratio (AR)<; 3dB, a reflection coefficient <; -10dB, and 23% circular polarization (CP) bandwidth. The monopole quarter-wavelength slot antenna design occupies half of the area on the corner of circuit board as compared to a half-wavelength slot antenna that requires double the area at the center of the board. This feature is attractive for compact wireless devices that operate at low frequencies in which planning for the smallest circuit board area combined with the shortest length for signal routing are the two major concerns. The antenna is extremely low-cost and does not require any truncation corner, reflector surfaces, or via connections, all of which increase the fabrication cost.