Javier Baliosian

Resource Slicing in Virtual Wireless Networks: A Survey

New architectural and design approaches for radio access networks have appeared with the introduction of network virtualization in the wireless domain. One of these approaches splits the wireless network infrastructure into isolated virtual slices under their own management, requirements, and characteristics. Despite the advances in wireless virtualization, there are still many open issues regarding the resource allocation and isolation of wireless slices. Because of the dynamics and shared nature of the wireless medium, guaranteeing that the traffic on one slice will not affect the traffic on the others has proven to be difficult. In this paper, we focus on the detailed definition of the problem, discussing its challenges. We also provide a review of existing works that deal with the problem, analyzing how new trends such as software defined networking and network function virtualization can assist in the slicing. We will finally describe some research challenges on this topic.

Decentralized Configuration of Neighboring Cells for Radio Access Networks

In order to execute a handover processes in a Radio Access Network, each cell has a configured list of neighbors to which such handovers are made. Rapid re-configuration ofthe neighborhood list in response to network failures and other events is currently not possible. To address this problem this paper suggests an autonomic approach for dynamically configuring neighboring cell lists and introduces a decentralized, three-layered framework. As a key element of this framework, a novel probabilistic protocol that detects and continuously tracks the coverage overlaps among cells is presented and evaluated. The protocol called DOC maintains a distributed graph of over-lapping cells. Dae to asing Bloom filters and aggregation techniques it exhibits a low traffic and computational overhead. A first series of simulation studies suggests that DOC is scalable with respect to network size and the namber of terminals.

A rule-based distributed system for self-optimization of constrained devices

During the last years there has been a strong research effort on the autonomic communications and self-management paradigms. Following this impulse, the academic community and the industry have proposed several architectures and techniques to allow network devices to make their own configuration decisions. Those proposals often include resource-expensive technologies such as complex inference machines, ontological modeling and probabilistic prediction that may not be suitable for the most pervasive and inexpensive network-enabled devices. This paper addresses this facet of the autonomic systems introducing RAN. This system aims to be a complete rule-based, distributed system specially designed and implemented to enable autonomic behavior on very constrained devices, such as domestic wireless routers with resources as low as 16 MB of RAM and 4 MB of storage memory. The RAN system was developed to serve the objectives of Rural Ambient Networks, a project that targets the so-called Digital Divide deploying low-cost wireless mesh infrastructure in rural communities. In this context, RAN, in autonomic and distributed manners, optimizes the network configuration to minimize the monetary cost that the community has to pay for using the IT infrastructure. Finally, this work presents an evaluation of RAN that shows how it makes possible to perform sophisticated optimization decisions with a very small overhead in terms of CPU and memory.

MIPv6 experimental evaluation using overlay networks

The commercial deployment of Mobile IPv6 has been hastened by the concepts of Integrated Wireless Networks and Overlay Networks, which are present in the notion of the forthcoming generation of wireless communications. Individual wireless access networks show limitations that can be overcome through the integration of different technologies into a single unified platform (i.e., 4G systems). This paper summarises practical experiments performed to evaluate the impact of inter-networking (i.e. vertical handovers) on the network and transport layers. Based on our observations, we propose and evaluate a number of inter-technology handover optimisation techniques, e.g., Router Advertisements frequency values, Binding Update simulcasting, Router Advertisements caching, and Soft Handovers. The paper concludes with the description of a policy-based mobility support middleware (PROTON) that hides 4G networking complexities from mobile users, provides informed handover-related decisions, and enables the application of different vertical handover methods and optimisations according to context.

Self-configuration for radio access networks

The ongoing work presented in this paper is aimed at bringing self-configuration capabilities into next generation radio access networks. We present the main concepts and architecture of our prototype. We also introduce briefly a novel strategy for foreseeing the outcome of enforcing policies integrating behaviour discovery techniques and finite state calculus into the conflict detection and resolution process. The main objective of this approach is to avoid instability problems of a distributed rule-based system

Policy-based self-healing for radio access networks

Various centralized, distributed or cooperative management systems have been proposed to address the demands of wireless telecommunication networks. However, considering the size, complexity and heterogeneity that those networks will have in the future, current solutions either do not scale properly, or have no support for automation, or lack of the flexibility and simple control that operators will need for managing future networks in a cost-effective way. To address this problem, we designed Omega, a distributed and policy-based network management system that uses rich knowledge-modeling techniques to develop self-configuration capabilities. Omega also implements a novel conflict-resolution method that uses high-level goals and machine learning techniques to optimize its policy-based decisions. Using simulations, in this paper we show how omega reduces the impact of a node crash on the overall availability of a radio access network by optimizing the lists of neighboring cells of the nodes in the vicinity.

Self management of rate, power and carrier-sense threshold for interference mitigation in IEEE 802.11 networks

Nowadays, it is common to find IEEE 802.11 networks that are deployed in an unplanned and unmanaged manner. Moreover, because of the low hardware cost and, trying to obtain better coverage and performance, a large number of devices are usually installed in reduced spaces causing high-density deployments. This kind of networks experiment several problems related with the shared nature of the transmission medium. In recent years, different transmit power control mechanisms have been proposed to palliate those problems, however, in some situations, the existing solutions can lead to an starvation problem. In this paper, we present a novel mechanism that manages data rate, transmit power and carrier-sense threshold to reduce this problem.

Self-managed content-based routing for opportunistic networks

Several countries such as Uruguay and Brazil are implementing the well-known One Laptop Per Child Program (OLPC) by which every child that assists to the primary school obtains in property a laptop with wireless capabilities. They carry their laptops from home to school and back every day and, as seen in the experience, they also carry their laptops to parks, community centers etc. This provides a wide platform for the deployment of Disruption Tolerant network applications. This paper presents a self-managed, opportunistic and content-based routing protocol that supports a network of environmental sensors implemented using consumer-grade wireless routers working together with OLPC laptops. We evaluate the impact of the density, diversity and connectivity of the mobile network on the performance of the protocol and we show how it self-configures it parameters to adapt to changing network conditions.

Embedded Rule-based Management for Content-based DTNs

Several countries such as Uruguay and Brazil are implementing the well-known One Laptop Per Child Program (OLPC) by which every child that attend to primary school obtains in property a laptop with wireless capabilities. They carry their laptops from home to school and back every day and, as we observed in our research, they also carry their laptops to parks, community centers etc. That provides a wide platform for opportunistic, delay tolerant, networking applications. This paper presents a lowcost, delay-tolerant, network of sensors implemented embedding high-level decision-making capabilities inside consumer-grade wireless routers working together with the OLPC laptops. The sensors are deployed at the living premises of children in environmentally vulnerable neighborhoods as well as at their schools, parks, etc. The environmental data collected by the sensors is carried to the school by the laptops and from the school to monitoring stations over the Internet. In this system, all the entities in the network are publishers and subscribers of con_guration commands, policy-rules and environmental data, building a exible, self-management solution.

Distributed auto-configuration of neighboring cell graphs in radio access networks

In order to execute a handover processes in a GSM or UMTS Radio Access Network, each cell has a list of neighbors to which such handovers may be made. Today, these lists are statically configured during network planning, which does not allow for dynamic adaptation of the network to changes and unexpected events such as a cell failure. This paper advocates an autonomic, decentralized approach to dynamically configure neighboring cell lists. The main contribution of this work is a novel protocol, called DOC, which detects and continuously tracks the coverage overlaps among cells. The protocol executes on a spanning tree where the nodes are radio base stations and the links represent communication channels. Over this tree, nodes periodically exchange information about terminals that are in their respective coverage area. Bloom filters are used for efficient representations of terminal sets and efficient set operations. The protocol aggregates Bloom filters to reduce the communication overhead and also for routing messages along the tree. Using simulation, we study the system in steady state, when a base station is added or a base station fails, and also during the initialization phase where the system self-configures.