This paper presents a new approach for localizing mobile phone users using the promising technique of stratospheric platform (SP) flying at altitudes 17-22 km high and a suitable Direction-of-Arrival technique (DOA). The proposed technique provides information about accurate locations for mobile stations - through high resolution DOA technique - which is very important for traffic control and rescue operations at emergency situations. The DOA estimation in this technique defines the user location using MUSIC algorithm which provides good accuracy comparable to the Global Positioning System (GPS) techniques but without the need for GPS receivers. Several scenarios for users’ locations determination are tested and examined to define the robustness of the proposed technique.

High-Altitude Platforms (HAP) is an emerging technology for mobile broadband communications and is capable of providing many advantages compared to conventional terrestrial and satellite systems. On the other hand, positional instabilities of HAP affect the system performance greatly. In this paper, a main problem concerning the rotation motion or yaw-shiftof HAP is described, analyzed, and its impact on the handover of cellular systems is also investigated. The total handover due to both user mobility and platform rotational positional instability is discussed and determined. An expression for the number of calls subjected to handover is deduced where it will be a function of users' density and their distribution in the cell, platform angular shift due to rotation, cell geometry, and number of active calling users. The analysis of this number shows the serious effects of the yaw-shift instability on the system performance.

Wireless Sensor Networks (WSN) has gained interest in many applications and it becomes important to improve its performance. Antennas and communication performance are most important issues of WSN. In this paper, an adaptive concentric circular array (CCA) is proposed to improve the link between the sink and sensor nodes. This technique is applied to the new High – Altitude Platform (HAP) Wireless Sensor Network (WSN). The proposed array technique is applied for two coverage scenarios; a wider coverage cell of 30 km radius and a smaller cell of 8 km radius. The feasibility of the link is discussed where it shows the possibility of communications between the HAP sink station and sensor nodes located on the ground. The proposed CCA array is optimized using a modified Dolph-Chebyshev feeding function. A comparison with conventional antenna models in literature shows that the link performance in terms of bit energy to noise power spectral density ratio can be improved by up to 11.37 dB for cells of 8 km radius and 16.8 dB in the case of 30 km radius cells that make the link at 2.4 GHz feasible and realizable compared to using conventional antenna techniques.

Wireless sensor network has many applications and very active research area. The coverage span of this network is very important parameter where wide coverage area is a challenge. This paper proposes an architecture for large-scale wireless sensor network (LSWSN) based on satellites and the High-Altitude Platforms (HAP) where the sensor nodes are located on the ground and a wide coverage sink station may be in the form of a satellite or a network of HAPs. A scenario is described for multilayer LSWSN and a study for the system requirements has been established showing the number of Satellites, HAPs and coverage per each sink according to the elevation angle requirements. The Satellite-HAP-Sensor multilayer LSWSN architecture has the feasibility for effective energy and earth coverage and is optimum for covering largely sparse regions.

In this paper, the cellular communications using high altitude platform (HAP) will be discussed including the coverage analysis and design. The cells are analyzed showing the main parameters affecting its shape, layout and area which are important in the cellular design stage. This HAP cellular system is very important to cross the gap of difficult extension of ground infrastructure especially for sparsely populated areas needing communications services. The system design is explained where the footprint of the HAP cell is demonstrated and the overall cellular layout is established. As a case study, the coverage of the HAP cellular system is proved to cover some areas in the Kingdom of Saudi Arabia (KSA) using several scenarios such as populated as well as long highways passing through desert areas. The HAP cells are generated using spot-beam antennas which are practically candidate. The simulation results show that a single HAP can provide hundreds of microcells for urban areas while covering very long highways that can extend to several hundreds of kilometers which is very useful in covering the long highways linking sparsely separated cities in KSA.

This paper proposes a new array geometry configuration to improve the two dimensional direction of arrival (2D-DOA) estimation of narrowband moving sources with less complexity. This new array is denoted by verticircular configuration, which is composed of both Uniform linear array (ULA) and Uniform Circular array (UCA) to avoid too much computation for 2D-DOA estimation. The proposed verticircular array is applied with the LPA nonparametric estimator to estimate multiple rapidly moving sources’ parameters (angles and angular velocities) for both azimuth as well as elevation directions. Simulation results show that this nonparametric technique is capable of resolving closely spaced sources provided that their velocities are sufficiently different with decreased computational complexity when using the verticircular array. Different scenarios are used to show the efficient LPA beamformer to distinguish sources that can have the same angles using their different angular velocities. In addition, this paper is to compare the performance of the 2D- LPA DOA estimation algorithm when using verticircular array (proposed array geometry) or rectangular planar array geometry. Simulation results show that the performance of the proposed method with less complexity than that obtained when using rectangular planar array.

Recently, stratospheric platform communications system (SPs) has gained great interest due to its superior performance compared to conventional communications systems. This paper addresses one of the major performance keys in SPs which is the cellular design based on adaptive concentric circular arrays (CCA). The proposed design technique aims to provide circular cells at any elevation angle to overcome the cell flattening and broadening which result in ellipsoidal cell shape. The cell footprint is controlled by adjusting the beamwidths which can be established by sectorizing the CCA and tapering the current amplitudes of the effective sectors by Hamming function while the others are muted and the resulted array is called Sectorized Hamming tapered CCA (SHTCCA). In this array, each sector has an angular width of 90o and some and two opposite sectors are fully fed while the others has less number of quarter-circular arrays. The tapering of the active sectors results in lower sidelobe levels which is a paramount improvement for the cellular systems. In addition, the SHTCCA is analyzed and optimized to provide the desired beamwidths at any elevation angle that are needed to design circular cell footprint.

In this paper, a new design for ring-shaped cells is introduced where to improve the power distribution and carrier-to-interference ratio (CIR) over the cell area. The designed cell has flat-top radiation pattern with minimal ripples in the service area while the out-of-cell area has lower radiation levels. The new design utilizes two weighting functions applied to a vertical linear array; the first is responsible for the flat-top design and the second smoothes the pattern and reduces the sidelobe levels. The resulted power pattern has a uniform distribution over the cell stripe with as small as 0.25 dB ripples and a uniform CIR values greater than 43 dB within the cells which reduces the burden of power control and increases the immunity to propagation problems.

In this paper, the MUSIC 2D-DOA estimation is estimated by splitting the angle into elevation and azimuth components. This technique is based on an array that is composed by a vertical uniform linear array located perpendicularly at the center of another uniform circular array. This array configuration is proposed to reduce the computational burden faced in MUSIC 2D-DOA estimation where the vertical array is used to determine the elevation DOAs (θs) which are used subsequently to determine the azimuth DOAs (∅s) by the circular array instead of searching in all space of the two angles in the case of using circular array only. The new Split beamformer is investigated and the performance of the MUSIC 2D-DOA under several signal conditions in the presence of noise is studied.