Michał Morawski

Network nodes play a game – a routing alternative in multihop ad-hoc environments ☆

Abstract A key aspect to consider in delivering data from one node to another in a communication network is finding a suitable path through the relaying nodes, i.e., routing. The standard routing solutions work well in the reliable networks, but do not achieve acceptable performance in low-power, noisy, and dynamic environments due to the high overhead associated with establishing a consistent view of the network. The paper presents a different solution to the problem of data delivery based on an evolutionary game between the network nodes. In the proposed approach, instead of forming a fixed path, the nodes take independent forwarding decisions. The set of nodes participating in the data transfer self-adjusts to the current networking conditions by playing the game, without involvement of a control plane. As a result, a low-overhead alternative to routing is obtained. The proposed solution is particularly well suited for the ad-hoc wireless networks serving time-sensitive data, e.g., it can provide an efficient communication platform for low-cost networked control systems.

On Implementation of Energy-Aware MPTCP Scheduler

The majority of networking devices currently available are equipped with a few communication interfaces. However, in most cases, only one of them is used for data transfer as dictated by the design premises of the fundamental transport protocol – TCP. Recently, a variant of TCP – Multipath TCP (MPTCP) – that allows for simultaneous transmission over different paths has been developed. While it allows for spreading the data stream among different interfaces and paths, the way it is actually performed has been left for further investigation. The stream splitting can be optimized according to different quality indicators. The paper discusses the implementation properties of an energy-aware load balancing method tested in a physical networking environment. A comparison with the reference solution is also provided.

Energy Efficient Dynamic Load Balancing in Multipath TCP for Mobile Devices

Over the last few years, one can observe a shift in preferences to use wireless media, including WiFi and cellular, rather than wired technologies for the communication purposes. On the other hand, a variant of TCP that allows for simultaneous transmission over different paths has been developed. This paper addresses the problem of optimal load distribution among the interfaces available at a networking device, e.g. mobile phone, with the objective of minimizing the overall energy consumption. A dynamic allocation algorithm, adapting to current, time-varying channel capacity is designed. Comparison with earlier approaches is provided and superiority of the proposed solution is demonstrated in numerical tests.

MPTCP remote peer control for increasing energy efficiency of downlink transmission

In the last few years one can observe a shift in preferences to use wireless media, including WiFi and cellular, over wired technologies for the communication purposes. On the other hand, a variant of TCP that allows for simultaneous transmission over different paths - Multipath TCP (MPTCP) - has been developed. This paper addresses the problem of optimal load distribution among the interfaces available at a remote networking device, e.g. mobile phone, with the objective of minimizing its energy consumption. A receiver-controlled load balancing algorithm that adapts to the current, time-varying channel capacity is designed. Comparison with earlier approaches is provided and superiority of the proposed solution is demonstrated in numerical tests.

Traffic control under scarce resources in wireless networks - a game-based approach

Typically, in order to organize the traffic in networks, some routing protocol is involved to establish and maintain paths for data flow. In the light of routing limitations in wireless environments, particularly restrictive when low power nodes are involved in a dynamic environment, the paper presents a different approach to organize the network traffic. In the proposed solution each node takes an independent and selfish decision about forwarding the data as a result of a game between the nodes.

Energy Efficient MPTCP Transmission Over Channels with a Common Bottleneck

The majority of networking devices currently available are equipped with a few communication interfaces. However, the design of the fundamental transport protocol – TCP – prohibits using them simultaneously. Recently, a variant of TCP – Multipath TCP (MPTCP) – that allows for parallel transmission over different paths has been developed. The protocol itself does not define any particular way of splitting the application data stream. Taking into account the proliferation of mobile terminals, a good quality indicator is the amount of energy dissipated by the communicating device. The previous works in the field assume that the paths established by the MPTCP stack are independent. This paper discusses the theoretical and practical aspects of stream splitting when the paths influence each other through a common bottleneck. A comparison with the reference solution is provided. The tests conducted in the public networking environment show a substantial improvement in energy economy.

Energy-efficient scheduler for MPTCP data transfer with independent and coupled channels

Abstract Over the last few years, one can observe a shift in preferences to employ wireless media, including WiFi and cellular, rather than wired technologies for the communication purposes. Since even simple networking devices are nowadays equipped with a few communication interfaces, the user’s experience can be elevated by simultaneous transmission over different paths, as offered by the recently standardized Multipath TCP (MPTCP). This paper addresses the problem of optimal load distribution among the interfaces available at a networking device, e.g., a mobile phone, with the objective of minimizing the overall energy expenditure. Depending whether the corresponding data paths are unrelated or influence each other, two cases are considered and two dynamic allocation algorithms are designed. The design procedures are set on the formal grounds of convex optimization and extremum seeking control. An experimental comparison with the earlier MPTCP scheduling solutions shows superiority of the proposed algorithms in terms of energy requirements. In particular, it is shown that in the case of coupled channels, the energy savings can reach several percent without throughput degradation.

Energy efficient MPTCP transmission — Scheduler implementation and evaluation

Nowadays, if one purchases a communication device it is typically equipped with a few network interfaces. Similarly, a professional service in the Internet is run via a couple of interfaces to avoid a single point of failure. Despite the existence of many transmission paths, most of data is expedited and received by the same interfaces. The remaining ones serve as backup only, according to the premises of the fundamental transport protocol — TCP. Although networking devices allow for bundling channels, it is executed at the link layer and thus unusable in the Internet. This functional gap has been filled by a variant of TCP that permits simultaneous transmission over a few paths — Multipath TCP (MPTCP). MPTCP allows for spreading the application data stream among different interfaces or paths, yet the way the splitting is actually performed has not been standardized. This task can be optimized to satisfy various quality indicators. The paper presents a continuation of the work on energy-aware optimal load balancing method, addressing implementation issues in a real networking environment. A comparison with the reference solution is also provided.

Remote quasi-soft variable structure control of dynamic plants with actuator saturation

Implementation of a remote control setup requires handling the issues of finite sampling rate at the communication interfaces, as well as the delay and uncertainty of information transfer through network channels. With the effort to shorten the convergence time while retaining smooth inputs under actuator saturation soft Variable Structure Control (VSC) can be used. The favorable properties of the classical - continuous-time - formulation of soft VSC is extended in this work to discrete-time systems with multi-period delay. The control system design and stability analysis are performed directly in discrete time domain. The controller properties are proved analytically and verified in experiments involving inverted pendulum-on-a-cart system steered remotely via a communication network.

Soft Variable Structure Control in Sampled-Data Systems with Saturating Input

In the effort to achieve high convergence rate, at the same time avoiding implementation difficulties and poor robustness of time-optimal controllers, the concept of soft Variable Structure Control (VSC) may be applied. The classical formulation of soft VSC in continuous time domain assumes smooth switching among an infinite number of controllers. Since nowadays control laws are implemented digitally, changing the control structure is limited to sampling instances, which leads to quasi-soft VSC. The paper investigates how the favourable characteristics of dynamic soft VSC can be extended to input-constrained systems with finite sampling. The design procedure and stability analysis are conducted directly in discrete time domain. The resulting nonlinear control law is synthesised into a form substantially different from its continuous-time counterpart. However, smooth control action and fast convergence of continuous soft VSC is retained. The properties of the obtained control system are formally proved and confirmed experimentally.