This paper presents NANCY, a system that generates adaptive bit rates (ABR) for video and adaptive network coding rates (ANCR) using reinforcement learning (RL) for video distribution over wireless networks. NANCY trains a neural network model with rewards formulated as quality of experience (QoE) metrics. It performs joint optimization in order to select: (i) adaptive bit rates for future video chunks to counter variations in available bandwidth and (ii) adaptive network coding rates to encode the video chunk slices to counter packet losses in wireless networks. We present the design and implementation of NANCY, and evaluate its performance compared to state-of-the-art video rate adaptation algorithms including Pensieve and robustMPC. Our results show that NANCY provides 29.91% and 60.34% higher average QoE than Pensieve and robustMPC, respectively.

With the successful deployment of the fourth-generation cellular networks around the world, long-term evolution (LTE) and LTE-advanced (LTE-A) have become key technologies to enable Internet of Things (IoT) applications. To accommodate various streaming data of IoT applications, LTE/LTE-A standards have defined several quality-of-service (QoS) classes for different traffic characteristics, in terms of traffic bit-rate, tolerable delay, and packet loss rate. Moreover, to meet the stringent power-saving requirements for IoT devices, LTE/LTE-A standards also have defined the discontinuous reception/transmission (DRX/DTX) mechanism to allow devices to turn off their radio interfaces and go to sleep when no data need to be received or transmitted from/to the evolved Node B (eNodeB).

GEO satellite communication systems are an efficient approach for broadband Internet provision on high-speed trains, but some work is still needed to allow a seamless service. This paper deals with improving the TCP performance using vertical handovers (based on MIH) from the satellite to a terrestrial wireless segment (hybrid network) and viceversa to cover tunnels. We have shown that TCP goodput behavior and convergence time can be improved by means of suitable accelerated TCP versions or with cross-layer methods. This work has been carried out within the framework of ESA SatNEx III NoE (Contract RFQ/3-12859/09/NL/CLP).

Satellite networks can provide the possibility to access communication services on wide areas of the earth; this characteristic coupled with the support of user mobility allows satellite networks having unique features well suited for different scenarios, like: land mobile, aeronautical, maritime, transports, rescue and disaster relief. Mobile satellite networks, however, entail crucial technological challenges, such as: link budget, antenna technologies for both the satellite and the mobile terminal, and efficient utilization of the radio spectrum. This paper investigates these aspects and provides an analytical framework that can be used to evaluate the characteristics of satellite networks in the design phase as well as for their operational phase. In particular, quantitative comparisons are presented here for different systems in terms of supported user density, bandwidth efficiency, and mobility aspects.

Space communication protocol standards-transport protocol (SCPS-TP) is a set of extensions to transmission control protocol (TCP) aimed at improving TCP performance over space links. Some work has been done on performance evaluation of SCPS-TP based on its methodology, or by testing it as an isolated entity or over satellite that deploys performance enhancing proxies (PEPs). It is needed to have an experimental evaluation of SCPS-TP in coping with heavy noise using the complete SCPS protocol stack, especially by comparing it with state-of-the-art terrestrial TCP. This paper describes an experimental evaluation of SCPS-TP over congestion free, error-prone, high-latency, point-to-point space links, through file transfer experiment by running the actual SCPS protocol stacks via a testbed. The results reveal that SCPS-TP is more tolerant of heavy noise and has significant throughput advantages over TCP. The performance advantage of SCPS-TP in a lossy link is attributed to its novel SNACK scheme and the advantage in asymmetric channel is from the contributions of the channel rate control and acknowledgment reduction mechanisms.

We propose a model for analyzing the QoS performance measures in a cellular wireless mobile network with call admission control (CAC) and adaptive channel allocation (ACA). The proposed model considers cross-layer (physical/radio link/network) parameters to analyze both the call-level and the packet-level performances. In the network layer, call admission control (CAC) is responsible for deciding whether an incoming call can be accepted or not such that the performances of the ongoing calls do not deteriorate below the acceptable level. Also, an adaptive channel allocation (ACA) scheme is used to maximize the utilization of the radio resources. In the physical layer, adaptive modulation is used to adjust the packet transmission rate according to channel quality. Different QoS measures such as new call blocking probability, handoff call dropping probability, radio link level packet dropping probability and average packet delay are obtained. The analytical results are validated by extensive simulations. We also present typical applications of the proposed analytical model

MANET techniques are critical to the success of emerging modern warfare concepts and are required to support communications for mobile military platforms, including ships, aircrafts, and ground vehicles operating in a highly dynamic and mobile tactical communications network without fixed infrastructure. Research in Mobile Ad Hoc Networking has increased dramatically over the last few years with significant work in hardware architectures, media access routing, and protocols. Until now, most of the work has been in simulation and small-scale laboratory demonstrations due to the significant resources required to implement an actual network with sufficient nodes to fully exercise the capabilities of both the hardware and software. Harris has built a flexible demonstration environment that enables the exercising of numerous network functions while still accomplishing research and development of the network protocols. The testbed, assumed in this paper, allows the system to be exercised in an outdoor environment that closely approximates the physical environment that the system will be operated in.

The next generation global communication network infrastructure is designed to be all IP based, supporting various heterogeneous core and access technologies for broadband and mobile user applications. In this paper, we discuss the trends of broadband satellite communication networks to meet the emerging aeronautical and fast train applications, and mobile users, in providing ubiquitous global coverage. Mobile satellite systems will be fully integrated with wireless networks and terrestrial segments. The technical challenges for future broadband satellite systems will be to insure seamless integration between satellite and wireless systems and without compromising quality of service (QoS). We discuss briefly the technical challenges and possible solutions, including a QoS reference model, traffic management, dynamic bandwidth allocation, cross-layer protocol design, satellite TCP, mobility management, satellite IP security, internetworking and standardization issues to realize heterogeneous networks.

Future broadband satellite access networks will provide user connectivity via a return channel from a centralized hub. The forward channel can be embedded into the broadcast channel yielding asymmetric bandwidth ratios of 10:1 or greater. To meet such a bandwidth asymmetry as well as the required quality of service, QoS, selection of multiple access and media access control protocols plays a significant role among other design issues. In most of the recent satellite access networks, the forward traffic is broadcasted to satellite interactive terminals (SITs) using the ETSI specified DVB-S protocol. For the return channel multiple access protocol, options based on multi-frequency time division multiple access (MF-TDMA), code division multiple access (CDMA) and random multiple access (RMA) are available. We present a comparative overview of connection- and contention-oriented multiple access and focus on the use of spread ALOHA by using one single long code.

ABR traffic management for point-to-multipoint connections controls the source rate to be the minimum rate supported by all the branches of the multicast tree. A number of algorithms have been developed for extending ABR congestion avoidance algorithms to perform feedback consolidation at the branch points. This paper discusses various design options and implementation alternatives for the consolidation algorithms, and proposes a number of new algorithms. The performance of the proposed algorithms and the previous algorithms is compared under a variety of conditions. Results indicate that the algorithms we propose eliminate the consolidation noise (caused if the feedback is returned before all branches respond), while exhibiting a fast transient response.

We study the performance of selective acknowledgements (SACK) with TCP over the ATM-UBR service category. We examine various unspecified bit rate (UBR) drop policies, TCP mechanisms and network configurations to recommend optimal parameters for TCP over UBR. We discuss various TCP congestion control mechanisms compare their performance for LANs and WANs. We describe the effect of satellite delays on TCP performance over UBR and present simulation results for LANs, WANs and satellite networks. SACK TCP improves the performance of TCP over UBR, especially for large delay networks. Intelligent drop policies at the switches are an important factor for good performance in local area networks.