This paper looks into the relatively new field of high altitude platform stations. HAPS is seen as a 'middle ground' between the terrestrial and satellite cases, and aims to exploit of the advantages of both types of system. Since HAPS is such a new field, this paper focuses on the technology behind a HAPS communications system, how this has developed, and compares it to the terrestrial and satellite equivalents. One important area that is being investigated is the applications for which HAPS should be used. This is a critical issue if a significant business case is to be made for HAPS. Worldwide HAPS projects and research issues are also highlighted. Finally, the review concludes with the remarks on the future of HAPS for wireless communications systems.

Small cell networks are currently seen as a new way to satisfy the increasing wireless traffic demand. The proximity of base stations to subscribers brings many possibilities for the development of new applications, including new offerings based on cloud computing. Smartphones can directly offload applications to close base stations, provided that these are equipped with additional computational and storage resources. The cloud concept applied in the framework of small cells can also combine radio and computation aspects in order to optimise the service delivery. This paper introduces a new element called the Small Cell Manager (SCM), which optimises the overall operation of a cluster of cloud-enabled small cells. The SCM, aware of the cluster situation in terms of both radio and cloud aspects, interacts not only with the cloud-enabled base stations, but also with LTE core network components. To that end, different possibilities for the general architecture of a small-cell-cloud are analysed. Furthermore, the paper describes different evaluation criteria an LTE operator has to consider before adopting this approach in order to optimise the required investment and maximise benefits.Peer ReviewedPostprint (published version

Emergency Broadband Access Network (EBAN) is a balloon-based broadband wireless access flies in low altitude (100-500 meter) offering various emergency applications. One of the applications may include IP video camera allowing the authority to observe the affected area and act accordingly. The emergency team can use WiFi coverage from EBAN sky station to get internet access, VoIP, video conference and tailored emergency applications such as Emergency Medical Care Information System (EMCIS). Atmospheric disturbances and its effect to the system performance are considered in term of platform and communication design. WiFi solution is selected because of its popularity and relatively easy to deploy. According to the trial result the WiFi-based EBAN system is able to provide coverage about 5.5 km radius or 72 km square from sky station at altitude 440 meter.

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Abstract-In this paper, we propose a cross-layer design approach using perfect prediction-based wireless channel conditions to improve the performance of a multicast packet scheduler over satellite network environments in the downlink transmission. The satellite channels are modeled in single and multi-environments with different values of Rician K factors and its corresponding elevation angle, mean and standard deviation values. From simulation results, the channel state information (CSI) of each user in the multicast group is considered and becomes the condition for the transmission of the multicast packet. We assume the users suffer slow-varying channels such that the CSI update is within the time interval for slot allocation. The result indicates that a positive performance improvement is gained by adopting a cross-layer-design approach in a fading environment. By obtaining the CSI before transmitting multicast flows, the approach reduces unnecessary transmission of background traffic and hence reduces unnecessary resource allocation and retransmission requests.