José María Molina-García-Pardo

A Broadband Pattern Diversity Annular Slot Antenna

An annular slot antenna suitable for pattern diversity in wideband applications is presented. Pattern diversity is obtained by feeding the antenna simultaneously with two microstrip lines printed on the back of the substrate, which generate orthogonal radiation patterns. Two shorts placed at 45 degrees between the microstrip lines and in the opposite direction ensure an isolation above 15 dB according to measurements. The antenna operates in the range of frequencies from 3 GHz to 12 GHz (1:4 bandwidth) and covers many different standards (Wireless-LAN, HIPERLAN2, WIMAX, UWB). Simulations and measurements for return loss, isolation and radiation patterns are presented. Furthermore, measurements have been carried out in a real multipath environment in order to evaluate pattern diversity performance. Results of measurements of the correlation coefficient and diversity gain over the entire operating bandwidth show that the antenna is suitable for antenna diversity systems.

Radio Channel Modeling for 4G Networks

This chapter is dedicated to radio channel modeling for 4G networks. In addition to recent results in the area of 4G channel modeling at large, including complex environments such as aircrafts, COST 2100 has dealt with a number of specific topics which are presented in this chapter. Improved deterministic methods, including models of diffuse components are detailed in Sect. 3.2. The developed models namely propose new methods to account for macroscopic diffuse scattering in ray-tracing tools. The measurement-based modeling of the same diffuse or dense multipath components has represented one major research topic in COST 2100, especially regarding the extraction of such components from experimental data (Sect. 3.3). Another important topic of research has concerned the modeling of the polarization behavior of wireless channels (see Sect. 3.4), as multipolarized antenna arrays appear more and more as a realistic implementation of MIMO systems. The specific representation and modeling of multilink scenarios is dealt with in Sect. 3.5. Considering the correlations between multiple links is a significant requirement to design robust schemes in cooperative, relay or multihop networks. Finally, the COST 2100 model is presented in Sect. 3.6. Starting from a single-link implementation based on the COST 273 model (available online), it builds upon the work described in this chapter to propose an updated version of the COST 2100 model including enhancements such as diffuse and cross-polar components, as well as multi-link aspects.