High Altitude Platforms and 3G Mobile Systems

High Altitude Platforms (HAPs) can combine the benefits of both terrestrial and satellite communications: low Free Space Loss when compared to satellites and limited shadowing at high elevation angles. The cell size in HAPs is far more limited by an antenna radiation pattern than a terrain profile. A major advantage of using HAPs is the low cost of deployment and, especially in the event of a disaster, their rapid deployment. The frequency spectrum for 3G mobile networks (around 2 GHz) has also been allocated to HAPs.

Iteration-Based Simulation Approach

In the radio network planning of third generation mobile networks the problems of capacity and coverage cannot be separated. Coverage prediction process in 3G systems is specific by the interference estimation and so the application of iteration-based simulations seems to be necessary to study the 3G networks behavior in realistic scenarios. The objective was the implementation of different propagation prediction methods for a variety of areas urban/suburban) and subsequent simulations of system-level parameters of 3G networks provided via HAP using the iteration-based simulation approach in order to show the basic parameters of HAP 3G networks that are important for radio network planning.

The effect of Antenna Power Roll-Off

It has been shown that the antenna power roll-off required to achieve optimal cellular capacity ranges between -10 and -35 dB, significantly larger than has been used in many of the 3G HAP studies to date (-3 dB).

Provision of 3G Mobile Services in Sparsely Populated Areas Using HAPs

It was shown that for large cells with a radius of 30 km in a homogenous hexangular deployment, the value of antenna power roll-off is a trade-off between the cell capacity and the quality of coverage.

Coexistence of Terrestrial and HAP Networks

Disaster scenario

         

           

Propagation Prediction for HAP 3G and 4G Systems

  • Measurement Campaign - Rooftop Diffraction Loss Measurements and Penetration Loss Measurements. Experiments were performed using 2.0 GHz, 3.5 GHz, and 5.5 GHz output, representing the frequency bands for 3G, Mobile WiMAX and WiMAX systems. A 9m long remote controlled airship was utilized.
  • Elevation Dependent Shadowing Model. Four basic types of environment; LOS Probability - a simple function was found to approximate the simulated data; Additional Shadowing Loss - a simple fractional rational function was derived as a best fit to simulation results; the model can be used to generate random shadowing loss or in a classical form of CDF.
  • An empirical model to predict penetration loss into buildings was developed based on measured data obtained using a remote-controlled airship. The measurement/modeling was carried out in different positions and in different types of buildings at 2.0 and 3.5 GHz.
     

         

        

Results

  • Possibilities of applying HAPs to provide 3G(3.5G) mobile services in various scenarios were studied
  • Optimization of classical single gain circular beams
  • Possibilities of application and optimization of elliptical beams
  • New method for the optimal application of circular antenna beams
  • Elevation dependent shadowing model for mobile communications via HAPs in built-up areas
  • Empirical model to predict penetration loss into buildings from HAPs based on the measurement campaign
  • System level simulations has proved that HAPs are perfectly capable of providing UMTS services in different environments
     

Supported by

  • HAPCOS – COST Action 297, High Altitude Platforms for Communications and Other Services, 2005-2009
  • Advanced Communication Systems and Radiowave Propagation Modelling for High Altitude Platforms, Czech Ministry of Education, Youth and Sports, grant no. OC 092, 2006-2009
     

Selected Papers