1,721,098 research outputs found
The use of satellite in 5G networks: the technological step forward and perspectives due to the VIBeS project
No full text5G system is a really disruptive new concept of telecommunication network because it will make use of all the up to date technologies both at physical and network management layer. It will represent a revolution especially for what concerns the latter aspects in particular introducing the concept of slicing. Thanks to their peculiar characteristics satellite systems can contribute to realize this revolution, offering performance in some very important scenario that will guarantee to satisfy 5G target requirements. The VIBeS project, funded by ESA, has reached very meaningful achievements in this line. The paper summarizes the main outcomes of the project and draws the significant perspectives that are now opened
Performance evaluation of an optimized intersegment handover procedure for hybrid constellation satellite systems
No full textA generalized N-state model to characterize satellite diversity for arbitrary number of satellites in case of uncorrelated channels
No full textEnhancing TCP performance over hybrid wireless terrestrial-satellite networks
No full textThis paper addresses the study of TCP performance over a heterogeneous network, where the access to IP based services is provided through the integration of terrestrial and satellite wireless technologies. This architecture is particularly suited for example for emergency communications, but presents some drawbacks in case TCP is used as transport protocol. The analysis of a solution for transport layer performance enhancement adopting TCP splitting agents at the edges of satellite link is discussed, using either a standard TCP or TCP Noordwijk for the inner connection between satellite terminal (ST) and satellite gateway (satGW). TCP-Noordwijk is a new transport protocol designed specifically for the satellite environment. This approach will be compared with a standard end-to-end TCP connection solution. Network Simulator NS-2 has supported the whole analysis and showed results which greatly demonstrate the advantages coming from the use of the split architecture and in particular adopting the TCP-Noordwijk transport protocol as inner connection
Improving performance of TCP-based applications over DVB-RCS links
No full textDVB-RCS links, as well as most of VSAT systems, to improve TCP performance usually consider a PEP solution. The SatLabs group of the European Space Agency issued I-PEP, selecting SCPS-TP as transport protocol, which supports two congestion control schemes: TCP Vegas (default) and van Jacobson’s Slow Start and Congestion Avoidance. In both cases the most popular TCP-based applications, i.e. Web browsing and e-mail, achieve very poor performance especially when DAMA schemes run at the MAC layer. In this frame, TCP Noordwijk has been specifically designed to optimize performance of short TCP- based data transfers over DVB-RCS DAMA links, meeting the requirement to be compatible with I-PEP specifications. This paper presents an overview of TCP-based application criticalities over DVB-RCS links and shows how TCP Noordwijk improves performance
End-to-end network requirements for 3GPP Voice over Wi-Fi (VoWiFi) service
Full text link4G mobile networks were the first to allow packet-switched voice calls, supported by an optional IP-based infrastructure called IP Multimedia Subsystem (IMS). These are part of the Voice over Long Term Evolution (VoLTE) service, called afterwards Voice over New Radio (VoNR) in 5G. In parallel, 3GPP defined the possibility of user terminals accessing either a 4G Evolved Packet Core (EPC) or a 5G Core (5GC) Network also via non-3GPP access. Non-3GPP access represents an alternative to the use of 4G/5G licensed frequencies of the MNO, leveraging Internet connectivity of an Internet Service Provider (ISP) to perform the same IP-based 4G/5G services, and in particular VoLTE/VoNR. Even though, especially for untrusted non-3GPP access, any IP-based access technology is applicable, the initial reference is Wi-Fi access, which is in practice available in all Smartphones. Consequently, the new 3GPP Voice over Wi-Fi (VoWiFi) service was introduced, also called commercially Wi-Fi Calling. VoWiFi is then subject to network conditions not fully under control of the Mobile Network Operator (MNO), not only related just to the Wi-Fi access but to the whole end-to-end data path across shared networks and the Internet. In this article, the VoWiFi technology and protocols are presented in detail, through a review of 3GPP specifications and by performing real calls using a national LTE MNO and a Xiaomi smartphone. The aim of the article is presenting the application traffic pattern and assessing the network conditions under which VoWiFi calls have good quality. These results are useful to define end-to-end Network requirements for assuring a satisfactory VoWiFi service to end users
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