Abstract
We investigate the performance and coexistence techniques for worldwide interoperability for microwave access (WiMAX) delivered from high altitude platforms (HAPs) and terrestrial systems in shared 3.5 GHz frequency bands. The paper shows that it is possible to provide WiMAX services from individual HAP systems. The coexistence performance is evaluated by appropriate choice of parameters, which include the HAP deployment spacing radius, directive antenna beamwidths based on adopted antenna models for HAPs and receivers. Illustrations and comparisons of coexistence techniques, for example, varying the antenna pointing offset, transmitting and receiving antenna beamwidth, demonstrate efficient ways to enhance the HAP system performance while effectively coexisting with terrestrial WiMAX systems.
Highlights
High altitude platforms (HAPs) are either quasi-stationary airships or aircraft operating in the stratosphere, 17–22 km (72 000 ft) above the ground and have been suggested as a way of providing the third generation (3G) and mm-wave broadband wireless access (BWA) [1,2,3]
When the terrestrial system coverage area starts to overlap the edge of H-BS coverage area, CINRH falls rapidly below 0 dB since the user on the edge of coverage (EOC) area of H-BS is much closer to the terrestrial base station (T-BS) and receives much more interference power
We could see the antenna gain with different spacing distances. It shows that curves fall more rapidly to the sidelobe level with the wider spacing distance on the left side of the coverage area, for example, when the spacing radius is equal to −20 km, the signal from the left edge of the coverage area will enter into its sidelobe level
Summary
High altitude platforms (HAPs) are either quasi-stationary airships or aircraft operating in the stratosphere, 17–22 km (72 000 ft) above the ground and have been suggested as a way of providing the third generation (3G) and mm-wave broadband wireless access (BWA) [1,2,3]. HAP systems have many useful characteristics including high-receiver elevation angle, line of sight (LOS) transmission, large coverage area and mobile deployment, and so forth. These characteristics help making HAPs competitive when compared to conventional terrestrial and satellite systems, and they can contribute to a better overall system performance, greater system capacity, and cost-effective deployment. Related research [6,7,8] has been carried out to examine the WiMAX downlink performance from an individual HAP system and coexisting with terrestrial systems.
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