Flow-induced molecular communications are a promising communication paradigm based on the exchange of molecule concentrations in a continuous fluid, guided and directed through microfluidic pipes. An emerging approach to implement this type of communications is based on discrete (or droplet-based) microfluidics. It exploits the idea to represent binary information by encapsulating the signaling molecules inside droplets, which are dispersed in an immiscible fluid and delivered, through micro pipes to the destination. The objective of this paper is to study a binary droplet-based microfluidic system for flow-induced molecular communications from an information theoretical perspective. To this end, we first show that the binary discrete microfluidic channel is characterized by memory and anticipation. Accordingly, we provide a mathematical model based on a finite-state Markov chain. Finally, we evaluate the capacity of the binary droplet-based microfluidic channel.

In the last decade, one of the main goals in wireless telecommunications has been to reduce energy consumption of mobile devices. However, making a network device green can cause performance deterioration. The target of this paper is to propose a cross-layer approach for the design of a mobile video cloud for the uplink transmission towards the Internet. The proposed approach is adaptive in both the video sources and the wireless transmitter. A source Rate Controller is applied to compensate transmission bandwidth reduction due to the energy saving policies. Energy saving in wireless transmission on the mobile cloud cellular channel is achieved by introducing an energy-efficient ARQ protocol. This protocol can apply different transmission laws, in order to exploit the correlation of the cellular channel behavior. An analytical model of the system is defined to compare the transmission laws, and provide some design guidelines to choose one of them and design its parameters.

In the last few years, the ever increasing attention to the eco-sustainability of Internet has pointed out the need of providing advanced power management schemes in network devices, in order to be able to reduce energy consumption according to the traffic load. In this context, starting from the observation that most of the traffic of today's Internet is carried by TCP, we focused on the impact that the dynamics of the TCP congestion control may have on energy efficiency of end hosts. In this paper we demonstrate that great energy consumption is related to network congestion conditions. Moreover, we propose to use a technique, called Active Window Management (AWM), with the aim of driving TCP sending rate according to the network available bandwidth, so improving congestion control and providing high TCP performance. AWM requires no changes to any TCP version. We demonstrate that the TCP traffic shaping performed by AWM allows a great reduction of the energy consumption in end hosts, with respect to the case where only TCP is used as congestion control.

One of the most weighty matter in the Internet today is the waste of energy due to the fact that consumption of network nodes is not tuned with the input traffic. For this reason, the implementation of rate adaptation facilities in the routers constitutes a challenging problem to make the network energy efficient. Rate adaptation in the green routers is usually achieved by scaling the processing power according to the data rate the router has to manage; at this purpose the clock frequency driving the router processes can be modified according to the input data rate. In this context this paper, starting from a measurement study of the Reference Router implemented on the NetFPGA platform, defines a model of the consumed power as a function of both the managed input traffic and the available clock frequencies. As demonstrated in the paper, the model can be applied by router designers to choose the main router platform parameters, i.e. the number of clock frequencies and the clock frequency switching time, while respecting a given tradeoff between the percentage of energy saved and the maximum tolerated loss probability due to frequency switch.

The reference router implementation on the Net FPGA platform has been changed in order to hijack the incoming packets according to rules specified by the user through Net FPGA registers. This means that we are able to change any field of any incoming packets, of course, depending on whether we are changing TCP or IP header fields, we need to recompute the TCP or IP checksum and store them back into the packets. It might be useful to change information of the IP or TCP header or the data itself. For example, we could crypto the data, change the URL address in order to point to the desired web site or for URL filtering, change the priority information of a bunch of data, and much more. Our implementation works at user data path level and modifies packet fields if certain conditions defined by the user through Net FPGA registers are satisfied. The project has been implemented as a fully open-source project and serves as an exemplar project on how to build and distribute Net FPGA applications. All the code (Verilog, system software, graphical user interface, verification scripts, make files, and support tools) can be freely downloaded from the Net FPGA.org website.

Improving video streaming performance is a main target today for the development of services and related business opportunities in the Internet. For this reason the definition of an efficient video transport paradigm is yet a challenging task. The most common protocol for data transmission in the Internet is TCP but it has been widely believed not suitable for multimedia streaming because of bandwidth instability and retransmissions. However, the dominance of TCP makes desirable the possibility to use it without any modifications. The main idea of this paper is to improve the performance of video streaming by using TCP, by combining it with Active Window Management (AWM), an algorithm to be implemented by video content Providers in their Internet access router. Through an extensive analysis the paper demonstrates that thanks to AWM, packet losses are avoided while per-packet delivery delay is maintained almost constant, strongly decreasing transmission jitter; consequently the required video playout buffer can be substantially reduced with respect to the classical approaches.

Addressing performance degradations in end-to-end congestion control has been one of the most active research areas in the last decade. A huge number of techniques have been proposed in the past, but some of them miss the challenging target of both minimizing network delay and keeping goodput close to the network capacity (e.g., active queue management (AQM) techniques); others require changes in both network routers and hosts that make them difficult to deploy [e.g., eXplicit Control Protocol (XCP)]. In a previous paper, a novel mechanism, called Active Window Management (AWM), has been proposed by the same authors with the aim of controlling the queue length in network routers, maintaining it almost constant to achieve no loss, while maximizing network utilization. The target of this paper is twofold: 1) carrying out a deep analysis of the AWM algorithm stability to evaluate the impact of some system parameters on the performance of the whole system; 2) demonstrating that AWM can be gradually introduced, maintaining the compatibility with the current Internet. An extensive numerical analysis is proposed to demonstrate that AWM stabilizes the queue around a target value with small oscillations.

Many techniques have been proposed in the last few years to address performance degradations in end-to-end congestion control. Although these techniques require parameter tuning to operate in different congestion scenarios, they miss the challenging target of both minimizing network delay and keeping goodput close to the network capacity. In this paper we propose a new mechanism, called Active Window Management (AWM), which addresses these targets by stabilizing the queue length in the network gateways. AWM acts on the Advertised Window parameter in the TCP segment carrying the acknowledge, but it does not affect the TCP protocol. The proposed technique is implemented in the network access gateways, that is, in the gateways through which both the incoming and outgoing packets related to a given TCP connection are forced to go, whatever the routing strategy used in the network. We show that when the access gateways implementing AWM are the bottleneck in the networks, TCP performance is very close to that of a pseudo constant bit rate protocol providing no loss, while network utilization is close to one.