Pratip Chakraborty

SolarMesh - Deployment Aspects for Wireless Mesh Networks in Developing Countries

This paper presents the latest research activities within the project ”SolarMesh - Energy-Efficient, Autonomous, Wide-Area Wireless Voice and Data Network”. The project is specifically dedicated to develop reliable wireless communications infrastructure for rural areas in developing countries, such as in sub-Saharan Africa. Wireless mesh networks based on IEEE 802.11 Wireless LAN technology combined with intelligent functions for self-configuration and self-adaptation can provide affordable ICT infrastructure for access and backhaul operation while at the same time offering carrier-grade QoS for voice and data services. Specifically, the paper outlines how a coordinated wireless mesh network has to be dimensioned in order to fulfill user requirements in terms of bandwidth and delay. Based on comprehensive simulations, recommendations for node density, backhaul capacity, and number of gateways to fixed line backbone networks are presented.

Pareto-Optimal Topologies for Lifetime Extension of Coordinated Wireless Point-to-Point Networks

Coordinated wireless point-to-point networks constitute a reliable and cost-efficient technology for providing backhaul connectivity for access networks in remote or topologically challenging environments, e.g. mountainous regions. Their flexibility allows for joint operation with any kind of access networks (including cellular), temporary or mobile deployment (e.g., for sport or entertainment events), or for full-fledged alternative of wired backhaul infrastructure. This paper introduces a novel approach for optimizing the topology of such coordinated backhaul mesh networks based on a range of relevant parameters, among them total network capacity, current load in the access network, energy consumption of the considered topology, as well as battery level of nodes without continuous power supply. We present a Backhaul Topology Optimization (BTO) algorithm that, at its core, generates a pareto-optimal backhaul topology. We show that our algorithm extends the lifetime of such a backhaul network by up to 20% compared to a standard reference case while at the same time keeping network capacity, data throughput, and user outage at satisfactory levels.

Multi-objective adjacency matrix optimization for coordinated wireless backhaul networks

Coordinated wireless point-to-point networks constitute a reliable and cost-efficient technology for providing backhaul connectivity for access networks in remote or topologically challenging environments, e.g. mountainous regions. Their flexibility allows for joint operation with any kind of access networks (including cellular), temporary or mobile deployment (e.g., for sport or entertainment events), or for full-fledged alternative of wired backhaul infrastructure. This paper introduces a novel approach for optimizing the topology of such coordinated backhaul point-to-point networks based on a range of relevant parameters, among them total network capacity, current load in the access network, energy consumption of the considered topology, battery level of nodes without continuous power supply, as well as fairness of throughput allocation from user perspective. We extend our Backhaul Topology Optimization (BTO) algorithm by exploiting the given heterogeneous data to generate an optimal backhaul topology. We show that our algorithm extends the lifetime of such a backhaul network by up to 20% compared to a standard reference case while at the same time modestly improving the fairness of throughput distribution.

A distributed broker system enabling coordinated access schemes in autonomous wireless networks

Autonomous wireless networks play an increasingly crucial role in todays society. Harsh environmental conditions, challenging deployment topologies, unreliable (or non-existing) power grids, as well as misguided control procedures of communications infrastructures by governmental authorities have made autonomous communication infrastructures a valuable asset for long-term development and wealth of societies. However, such wireless networks are in an early phase of their development and need to incorporate necessary equipment and algorithms for autonomous operation. This paper presents a concept and a concrete simulation scenario showing how a distributed context management system and the data collected and distributed by such a system can improve the performance of an autonomous, coordinated wireless mesh network (ACWMN). Research agrees that it is context awareness that will transform todays networks to incorporate autonomous, coordinated behavior. We further depict a concrete example simulation scenario where the access capacity of an ACWMN with WLAN radio access technology is significantly increased by coordinating user access with upper limits on the number of users that can concurrently request data services.

A novel serious game engineering based interactive visualization and evaluation platform for cellular technologies

In todays world, mobile communication has become a ubiquitously used technology, currently on the verge of its fifth generation (5G). 5G anticipates higher traffic volume and connected device density than present. It further envisions variety of service types and use cases arising from them. Various 5G concepts are being developed in order to satiate the aforementioned challenges. One of the key tasks for 5G consortium however, is to present the developed technology and concepts to wider audience (academia, industry) and even convince decision makers from non-information and communications technology (ICT) industries. Thus, it is desired to have easy to understand illustrations of envisioned 5G use cases and proposed technical solutions, targeting the non-experts. The contemporary simulation framework has limited or no provision to dynamically visualize and interact with the simulation scenario, rendering it difficult to be used for marketing as well as academic purposes. In this paper, we propose a serious game engineering based 3D visualization and evaluation framework, which allows dynamic and interactive visualization of simulated scenario. The proposed framework is simulator agnostic which enables viewer to immerse oneself into the simulated scene, visualize key performance indicators (KPI) in almost real time and even interact with simulator by changing key simulation parameters. These features equip the proposed interactive visualization/evaluation platform (IVEP) to demonstrate the 5G use cases and developed concepts better, paving way for easier understanding and evaluation of the concepts even by non-experts.

On the reliability of solar-powered point-to-point radio backhaul networks

As of today, broadband connectivity in developing countries, particularly in rural areas, has not been realized in a satisfactory manner. Coordinated point-to-point radio networks constitute a reliable and cost-efficient technology for wireless backhauling to remote regions. In mountainous regions like the Alps, such networks are deployed to provide Internet connectivity to remote villages. In Sub-Saharan countries such as Tanzania, they serve as an increasingly popular solution to connect sparsely populated areas. However, due to the remote location of radio nodes, no power grid for reliable energy supply is available. Rather, backhaul nodes are equipped with photovoltaic (PV) modules that charge buffer batteries that in turn supply energy to the network equipment. Without sufficiently dimensioned batteries and solar panels, radio nodes are prone to failure which in turn result in network outages and limited service availability. Hence, the deployed equipment for autarkic power supply has to accommodate for periods of lull or overcast skies. In this context, this paper derives recommendations and general rules on how to dimension power supply components to allow for reliable point-to-point wireless backhauling.

Evolutionary approach for multi-objective optimization of wireless mesh networks

For a multi-hop wireless mesh network it is well known that network throughput as well as network energy consumption acts as two major performance metrics. Hence there is a real need to have a thorough study on how one can optimize both objectives simultaneously. In this paper, we take a evolutionary optimization approach to optimize the performance objectives. In order to stress on throughput and energy performance, we assume a simplified link layer scheduling by using orthogonal channels among the data links. We use the multiple reference point approach for the above multi-objective optimization problems which is intrinsically of discrete and combinatorial nature. During the course of approximating the Pareto Frontier, multiple reference points can be used instead of traditional methods. The multiple reference point approach has the benefit of parallelization by finitely partitioning the decision space.

Analytical model for dynamic allocation of spreading sequences in DS-CDMA

Spreading sequences are usually allocated to users irrespective of their channel conditions. In this paper we allocate sequences based on their channel conditions to improve the performance of the link model. We also propose an analytical model for the allocation scheme. We validate the analytical model on a down-link and evaluate its performance, to show an increased gain in the performance of the down-link model.