DES-Chan - A framework for distributed channel assignment

The DES-Chan framework eases the development process of distributed channel assignment algorithms in real wireless mesh network environments. It has been created to allow the implementation of a wide range of different channel assignment algorithms in order to allow studies of experimentally-driven research on distributed channel assignment.

Motivation

Multi-transceiver mesh routers allow the communication over several wireless network interfaces at the same time. However, this can result in high interference of the wireless interfaces leading to a low network performance. Channel assignment for multi-transceiver wireless mesh networks (WMNs) attempts to decrease the interference of simultaneous transmissions by exploiting the availability of fully or partially non-overlapping channels.

The implementation of algorithms and protocols for distributed channel assignment is a process which yields several challenges and pitfalls for the researcher. Common operating systems are not designed to support channel assignment algorithms out of the box. Thus, the researcher has to deal with operating system specifics, drivers for the wireless interfaces, and the capabilities and limitations of the particular hardware. If more than one particular algorithm should be studied, the same problems and services have to be addressed multiple times.

DES-Chan

The DES-Chan framework addresses these challenges and has been developed for experimentally-driven research on distributed channel assignment in real network environments. DES-Chan provides an abstraction layer to the low-level and operating system specific tasks. This abstraction layer enables the researcher to spend most development time on the algorithm logic instead of, for instance, memory management and handling the wireless interfaces. Additionally, DES-Chan provides basic services and data structures often required for typical tasks in channel assignment algorithms. For instance, appropriate data structures have been provided for network graphs, conflict graphs, and interference models.

Architecture and components

The DES-Chan framework comprises two main components as depicted in the following picture. DES-Chan Core is a Python library that provides common functions and data structures for channel assignment algorithms. The Neighborhood-Discovery module provides a basic service for each node to get information about all neighboring nodes.

DES-Chan has been developed to provide many services that are required by different distributed channel assignment approaches. The following components are included in the DES-Chan Core framework.

Interface Management - The interface management module acts as interface to the operating system and hides testbed-specific characteristics. It provides various functions for configuring network interfaces and getting information about their state.
Neighborhood-Discovery - The Neighborhood-Discovery module is a daemon that determines the links and their quality on each network node based on the ETX link metric.
Node Communication - With this module, the researcher can quickly develop the required protocol implementation for exchanging messages among the network nodes, for instance in order to propagate changes in channel assignment or to carry out three-way handshakes prior to the actual channel switch.
Network graph - This componend provides data structures for the network graph and the corresponding conflict graph.
Interference Models - Currently, the two-hop interference model is implemented for reference.

Implementations and results

coming soon

Source code

We are currently working on the first release of the DES-Chan framework. It will be published soon under the GPL and includes a tutorial covering the first steps of implementing a channel assignment algorithm with DES-Chan.