In this paper, we investigate the deployment and capacity of delivering mobile WiMAX based on IEEE 802.16e-2005 from aerial platform such as High Altitude Platforms (HAPs). A urban scenario and an suburban scenario with mobile broadband usages as complement or substitute to the fixed Internet connection are developed to compare the delivery of broadband services from terrestrial and aerial platforms. A deployment strategy is based on maximizing and meeting the networking traffic demand and coverage area. In the end, a comparison based on cell radii and capacities between services from aerial platforms and existing terrestrial based solutions, such as universal mobile telecommunications system (UMTS) and high speed packet access (HSPA) is proposed. Currently, most research has been done to develop advanced technologies to enhance standards to support a higher data rate in a cost-effective way for wireless communication systems. From analysis and investigation, aerial platform can provide a cost-effective solution for a large area with a medium to high traffic demand.

Since 1990s, the investigations of aerospace communication segment have not only been concerned with satellites, but increasingly with lower altitude repeaters flying in the stratosphere. They are the so-called high-altitude platforms (HAPs) with important advantages with respect to satellites in terms of reduced cost of implementation, deployment, and launch. However, HAPs are characterized by a reduced coverage, as compared with satellites. Nevertheless, in recent literature, HAPs are not regarded as competitors of the satellite technology. On the contrary, the emphasis is on the effective and seamless integration among heterogeneous aerospace segments (GEO, LEO, and HAP) and aerospace segments with terrestrial wireless networks in order to globally extend the broadband wireless connectivity. This paper is focused on the role of HAPs in providing global connectivity in future communication systems and services. Potentialities, enabling technologies, and challenges are presented from the perspective of the integrated terrestrial/HAPs/satellite communications infrastructure.

Uplink power control is a key radio resource management feature in the 3GPP Long Term Evolution (LTE). In order to adapt to changes in the inter-cell interference situation or to correct power amplifier errors, closed-loop adjustments should be applied. In this paper the performance of closed loop power control combined with fractional path loss compensation factor is studied, and an optimal value for the path loss compensation factor is investigated. The closed loop power control with fractional path loss compensation factor is found to improve the system performance in terms of mean bit rate by 68% and utilizes the battery power more effectively.

In this paper we investigate the possibility of multiple HAP coverage of a common cell area. In particular we study the uplink system performance since it is considered as a worst case scenario. In order to obtain further enhancement (interference mitigation) we also apply space-time diversity techniques, such as Single-Input Multiple-Output (SIMO) receive diversity or Multiple-Input Multiple-Output (MIMO) diversity, to improve the spectrum reuse in the multiple HAP scenario. We will show the level of improvement using SIMO and MIMO algorithms, the practical limits on the number of HAPs and SIMO/MIMO system dimension in response to traffic demands and the type of service used.

In this paper, we investigate the performance of a multiple access scheme based on orthogonal frequency-division multiplexing (OFDM) in High Altitude Platform (HAP) system for Wireless Sensor Network (WSN) applications. In our study, HAPs are used to replace the traditional gateway deployed on the ground and collect data from sensor nodes. Two scenarios of OFDM schemes with different subcarrier spacing are simulated in Rayleigh and Ricean fading environment. Results show the multiple access scheme based on OFDM for WSN can improve the performance against multipath transmission.

In this paper we study the depolarization effects caused by rain and ice particles in the troposphere on the performance of a multiple HAP (high altitude platforms) system employing multi-polarized compact MIMO antenna configurations. In order to reinforce the analysis, we first propose a novel multi-channel simulator that produces realistic time-series of the fading process affecting signal transmission in HAP systems. The proposed simulator takes into account the temporal, spatial and polarization properties affecting these processes. Finally, we analyse the impact of depolarization on the total capacity of the system. Simulation results show a significant drop in performance as the cross polar discrimination decreases.

Research towards meeting the higher demands for higher data rates was the main reason for the birth of an evolution technology towards the 4thgeneration mobile communication systems. This evolution to the current 3rdgeneration UMTS systems was given the name E-UTRA/UTRAN long term evolution (LTE) by the 3GPP. This paper analyzes the requirements for this evolution and evaluates the performance of the OFDM-LTE system under different propagation impairments (AWGN and multipath fading channels involving pedestrian and vehicular scenarios) in terms of bit and symbol error rates (BER and SER) for different modulation formats.

In this paper, we investigate a cost-effective wireless broadband service provision from high altitude platforms (HAPs) and an economical business model design. Different deployment strategies of HAP system are illustrated in terms of a stand-alone HAP system and in collaboration with terrestrial or satellite systems. An IEEE 802.16 fixed broadband service from HAP is examined to show the effectiveness of providing the service delivery. We propose a partnership-based business model for HAP system, which can be adopted for a cost-effective service delivery, and applied in different application scenarios with collaboration partners, e.g. information service provider (ISP), equipment vendors, and mobile network operator (MNO). Key factors of successfully delivering HAP services and collaboration with partners are investigated in terms of coexistence capability with major wireless network operators and different approaches for a cost-effective HAP service delivery.

This paper proposes a medium access control (MAC) protocol, termed as CD-MMAC, for wireless networks that utilizes multiple channels and incorporates opportunistic cooperative diversity dynamically to improve its performance. The IEEE 802.11b standard protocol allows the use of multiple channels available at the physical layer but its MAC protocol is designed only for a single channel. The proposed protocol utilizes multiple channels by using single interface and incorporates opportunistic cooperative diversity by using a cross-layer MAC. The new protocol leverages the multi-rate capability of IEEE 802.11b and allows wireless nodes far away from destination node to transmit at a higher rate by using intermediate nodes as a relays. The protocol incorporates opportunistic cooperative diversity by the design of a cross-layer MAC. The protocol improves network throughput and packet delivery ratio significantly and reduces packet delay. The performance improvement is further evaluated by simulation and analysis.

In this paper we assess the multipath propagation effects of a short-range wireless device operating at 2.4 GHz in an indoor office environment. The investigations are carried out using FEM simulations and measurement trials for NLOS and LOS propagation scenarios. The FEM simulations will also be used for assessing the influence on propagation when doors are opened or closed. Finally, we investigate a single-input multiple-output (SIMO) antenna receive diversity system utilizing different combining techniques to improve the performance over a fading radio channel in a NLOS propagation environment. Simulation results show that a substantial diversity gain would be achieved by using this system.

In this paper we address the potential gain of using various compact MIMO antenna array configurations in conjunction with HAP (high altitude platforms) diversity techniques in order to enhance the data rates in HAP communication systems. We also investigate the effects of spatial correlation and mutual coupling between the separate antenna elements on system performance. Simulation results show that although the capacity is degraded by correlation and mutual coupling, we still achieve significant capacity gain compared to the single HAP case. Simulations also show the existence of an optimum separation angle between HAPs that maximizes capacity.

Abstract A MIMO channel spatial decorrelation scheme based on semi‐definite programming is introduced. As a particular application example, the paper addresses the potential gain of using multiple antennas and MIMO–OFDM techniques in order to increase the bandwidth efficiency in satellite communication systems. In particular, we consider the increase in channel capacity that is possible by exploiting satellite and polarization diversity. A fundamental case is studied with three satellite branches, and where each transmit/receive antenna unit consists of six elemental electric and magnetic dipoles yielding six distinguishable parallel polarization channels per frequency. The numerical examples show that capacity increases linearly on a logarithmic signal‐to‐noise ratio scale where the constant of proportionality is the number of active parallel channels. In this respect, the simultaneous use of triple electric and triple magnetic dipoles has the potential to triple the capacity of an antenna system based on antenna units of single dipoles. Copyright © 2006 John Wiley & Sons, Ltd.

In this paper we address the potential gain of using compact MIMO antenna array configurations in conjunction with HAP diversity techniques in order to increase the data rates in HAP communication systems. Simulation results show that the MIMO system provides superior performance as compared to the single HAP case.