Channel assignment strategies for a high altitude platform spot-beam architecture (original) (raw)
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High Altitude Platforms may offer high spectrum efficiency by deploying multi-beam, multi-cell communications networks. The properties of the antennas carried by the HAP payload are key to the effective exploitation of these benefits. This paper compares different models for the antenna sidelobe region and quantifies, in each case, the carrier to interference ratio for a 3 channel re-use plan. Networks of 121 and 313 cells are compared. We show how the ITU recommended pattern for the 47/48 GHz band leads to pessimistic results compared to an adapted pattern which fits that of measured data for an elliptic beam lens antenna. The method is then extended to consider other radiation patterns. Spectrum sharing issues are explored with reference to further ITU recommendations and comparison with measurement data. Finally, an ITU type cellular layout which uses the same antenna for each cell is compared to an alternative hexagonal layout where each cell has equal size.
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IEEE Transactions on Wireless Communications, 2003
In a wireless communications network served by a high altitude platform (HAP) the cochannel interference is a function of the antenna beamwidth, angular separation and sidelobe level. At the millimeter wave frequencies proposed for HAPs, an array of aperture type antennas on the platform is a practicable solution for serving the cells. We present a method for predicting cochannel interference based on curve-fit approximations for radiation patterns of elliptic beams which illuminate cell edges with optimum power, and a means of estimating optimum beamwidths for each cell of a regular hexagonal layout. The method is then applied to a 121 cell architecture. Where sidelobes are modeled as a flat floor at 40-dB below peak directivity, a cell cluster size of four yields carrier-to-interference ratios (CIRs), which vary from 15 dB at cell edges to 27 dB at cell centers. On adopting a cluster size of seven, these figures increase, respectively, to 19 and 30 dB. On reducing the sidelobe level, the improvement in CIR can be quantified. The method also readily allows for regions of overlapping channel coverage to be shown.
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Interest in high-altitude platforms (HAPs) has been increasing recently, especially with the rapid technical development in solar panels' efficiency, energy storage, antenna design, and lightweight materials for aircraft parts. These factors make high-altitude platforms more applicable in a wide variety of military, security, relief, and civilian applications. This paper provides overview on the high-altitude platforms and their advantages compared terrestrial and satellite communications. This paper also surveys the air-to-ground channel model used for HAPs, channel performance metrics, and optimizing various HAPs parameters.
High-Altitude Platforms for Wireless Communications
High-Altitude Platforms for Wireless Communications, 2008
The demand for high-capacity wireless services is bringing increasing challenges, especially for delivery of the 'last mile'. Terrestrially, the need for line-of-sight propagation paths represents a constraint unless very large numbers of base-station masts are deployed, while satellite systems have capacity limitations. An emerging solution is offered by high-altitude platforms (HAPs) operating in the stratosphere at altitudes of up to 22 km to provide communication facilities that can exploit the best features of both terrestrial and satellite schemes. This paper outlines the application and features of HAPs, and some specific development programmes. Particular consideration is given to the use of HAPs for delivery of future broadband wireless communications. and dynamic channel assignment/multiple access schemes for multimedia communications. He is now project manager for The University of York's contribution to the EU Framework V HeliNet project, namely the broadband communications programme. David is also a Director of
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This paper proposes a novel beamforming technique to form an arbitrary-shaped cell for the high altitude platforms (HAPs) mobile communications. The new technique is based on pattern summation of individual low-sidelobe narrow-beams which constitute the desired cell pattern weighted by an amplitude correcting function. The new cell pattern can be adapted to cover the main highways forming worm-shaped cells which may cover the highway for long distances up 100 km and it will has an important role in reducing frequent handoffs and signaling traffic of location updating from moving users over the long highways.
On the Capacity of Multicell Coverage Mimo Systems in High Altitude Platform Channels 1
2013
This paper is a comparative study between the performances of conventional terrestrial multicell Multiple Input Multiple Output (MIMO) working in a Rayleigh fading environment and its corresponding High Altitude Platform (HAP) system working under a different Path Loss (PL) model with the capacity as the performance metric of interest, calculated using the Singular Value Decomposition (SVD). Both systems are assumed to be affected by cochannel interference users in other cells.Simulation results show that the performance of multicell MIMO HAP dependent system outperforms its corresponding that works in terrestrial environment in terms of per user channel capacity.
IEEE Transactions on Aerospace and Electronic Systems, 2010
An investigation into the impact of antenna radiation patterns on the performance of a 3G mobile communication system provided a single high-altitude platform (HAP) is presented. Use of elliptical and circular beam antennas is examined for a 91-cell system. Crucial performance parameters are shown to be the mainlobe power roll-off and sidelobe level. It is presented that the optimum power roll-off from cell center to the cell edge ranges between 10-35 dB, which is dependent on the types of antennas used, sidelobe level, and antenna gain strategy employed. Elliptical beam antennas are proven to provide the best solution, but circular beam antennas with their gain adjusted to reduce the degree of cell overlap and compensate for increasing path loss are shown to provide similar performance, with the advantage that they are practically more realizable. It is shown that poorer overlap performance can be partially compensated for by an increased power roll-off at the cell edge, a strategy that is employed in the case of the gain adjusted circular beam antennas. The impact of cell radius and elevation angles is also assessed. I. INTRODUCTION Third generation (3G) mobile systems, e.g., UMTS (universal mobile telecommunications system), especially when supplemented with high-speed downlink packet access (HSDPA), should fulfill the increasing requirements for high-speed mobile data communications [1, 2]. The rapid deployment of UMTS networks is limited by many factors. In many instances, particularly in suburban and rural areas, coverage is the dominant consideration. High-altitude platforms (HAPs) will be situated in the stratosphere at an altitude from 17 to 22 km [3-6] and could be used as an alternative to a terrestrial component for UMTS 3G mobile networks or as a complementary element of terrestrial networks in providing telecommunication and data services in sparsely populated areas such as in Africa during disasters, terrorist attacks, etc. The frequency spectrum
On the capacity of multicell coverage MIMO systems in High Altitude Platform channels
The First International Conference on Future Generation Communication Technologies, 2012
This paper is a comparative study between the performances of conventional terrestrial multicell Multiple Input Multiple Output (MIMO) working in a Rayleigh fading environment and its corresponding High Altitude Platform (HAP) system working under a different Path Loss (PL) model with the capacity as the performance metric of interest, calculated using the Singular Value Decomposition (SVD). Both systems are assumed to be affected by cochannel interference users in other cells. Simulation results show that the performance of multicell MIMO HAP dependent system outperforms its corresponding that works in terrestrial environment in terms of per user channel capacity.