BOWL (Berlin Open Wireless Lab)

Overview

BOWL (Berlin Open Wireless Lab) network is a reconfigurable outdoor wireless network covering the TU-Berlin campus. It is composed of wireless nodes, equipped with multiple radio interfaces, on the rooftops of TU-Berlin buildings. Currently, the most commonly used configuration is a mesh network; however, other configurations are possible due to high built-in reconfigurability. Figure 1 shows the area covered by the BOWL network on the TU-Berlin campus.

The goal of the BOWL project is two-fold:

• To provide Internet access to TU-Berlin students and staff
• To provide a configurable wireless network to collaborators to enable various technologies, applications, services and scenarios to be evaluated

By bringing together users and wireless researchers in the same network, BOWL, to the best of our knowledge, is the first project that enables carrying research proposals to a semi-production environment. Therefore, BOWL is expected to make significant contributions to future mobile Internet research.

Figure 1: Area covered by the BOWL network on the TU-Berlin Campus

Implementation

Facts and Numbers

• The total number of deployed nodes is 55, including 46 outdoor rooftop nodes on TU-Berlin Campus and 9 indoor nodes @ T-Labs (10 more nodes expected @ indoor)
• > 40 hectares of TU-Berlin Campus is covered
• Network is deployed, functional and online since July 2009
• Accessible by TU Berlin community for Internet access
• Rooftop infrastructure is extensible to accommodate additional hardware

Hardware Infrastructure and Testbed

Figure 2: BOWL nodes

In contrast to production networks, BOWL nodes are deployed densely in the campus, allowing switching off a significant fraction of nodes without losing connectivity. This allows for effective evaluation of power control and interference issues in dense networks. Since nodes are deployed on rooftops, physical access to the nodes is limited. Hence, all nodes have a dedicated Ethernet connection allowing remote management. Additionally, majority of the nodes contain two independent units: the actual router and a simpler unit to manage the router in case of a malfunction. The secondary unit can also be used as a passive measurement and monitoring device.

BOWL Main Components

BOWL design brings together several components to achieve a reconfigurable live network. The main components include:

• Remote configuration management and monitoring: to remotely and automatically manage and configure the nodes in the outdoor network as well as check their status. During reconfigurations fail-over mechanisms are triggered to switch nodes to a safe state to maintain reliability to the users.
• Measurements and tracing: to provide user, system, and network level information
• Protocol toolkit: for protocol development. It consists of a software (Click-based) framework for the implementation of different layers of network stacks, and covers the data plane as well as the control plane.
• Support infrastructure: to enable software testing and validation.

Live Map/Control Interface

The dynamics in the network is illustrated in a live network map. Figure 3 depicts a snapshot of the BOWL network on 9th October 2009. The green nodes represent online access points; the red nodes are unreachable as they are newly deployed and not configured. The red dots represent the clients attached to the access points. The map depicts the “flow view”, where each flow is represented as a different colour line. It is also possible to change the view to the “topology view” to show the connectivity strength between different access points.

Figure 3: Live map displaying current state of the nodes

Demonstration Scenarios

Currently, the following scenarios can be exhibited in the BOWL network and be captured live on BOWL map:

• A mesh network configuration with single Internet gateway
• Network connectivity and traffic flow information
• Remote node management via transmit power and node on-off configurations
• Remote gateway activation and modification
• Remote routing protocol switching (OLSR – Optimized Link State Routing and DSR – Dynamic Source Routing are supported)
• Seamless mobility with a real-time view of client handovers

Publications

Ruben Merz, Harald Schiöberg, Cigdem Sengul, Design of a Configurable Wireless Network Testbed with Live Traffic, Tridentcom 2010

Mustafa Al-Bado, Anja Feldmann, Thorsten Fischer, Thomas Hühn, Ruben Merz, Harald Schiöberg, Julius Schulz-Zander, Cigdem Sengul, Benjamin Vahl. Automated Online Reconfigurations in an Outdoor Live Wireless Mesh Network. Demo at ACM SIGCOMM '09, August 2009

Harald Schiöberg, Ruben Merz, Cigdem Sengul. A Failsafe Architecture for Mesh Testbeds with Real Users. In Proceedings of the ACM MobiHoc Wireless S3 Workshop 2009, (Location: New Orleans, Louisiana, USA), Pages 29-31, ACM Press, New York, NY, USA, May 2009

Availability

The current state of the network is always available for view at: http://bowl.net.t-labs.tu-berlin.de

For more information please contact:
Ruben Merz at Ruben [dot] Merz [at] telekom [dot] de and
Cigdem Sengul at Cigdem [dot] Sengul [at] telekom [dot] de