1,434 research outputs found
Internet Traffic based Channel Selection in Multi-Radio Multi-Channel Wireless Mesh Networks
Wireless Mesh Networks(WMNs) are the outstanding technology to facilitate wireless broadband Internet access to users. Routers in WMN have multiple radio interfaces to which multiple orthogonal/partially overlapping channels are assigned to improve the capacity of WMN. This paper is focused on channel selection problem in WMN since proper channel selection to radio interfaces of mesh router increases the performance of WMN. To access the Internet through WMN, the users have to associate with one of the mesh routers. Since most of the Internet Servers are still in wired networks, the major dominant traffic of Internet users is in downlink direction i.e. from the gateway of WMN to user. This paper proposes a new method of channel selection to improve the user performance in downlink direction of Internet traffic. The method is scalable and completely distributed solution to the problem of channel selection in WMN. The simulation results indicate the significant improvement in user performance
State-of-the-art of distributed channel assignment
Channel assignment for Wireless Mesh Networks (WMNs) attempts to increase the
network performance by decreasing the interference of simultaneous
transmissions. The reduction of interference is achieved by exploiting the
availability of fully or partially non-overlapping channels. Although it is
still a young research area, many different approaches have already been
developed. These approaches can be distinguished into centralized and
distributed. Centralized algorithms rely on a central entity, usually called
Channel Assignment Server (CAS), which calculates the channel assignment and
sends the result to the mesh routers. In distributed approaches, each mesh
router calculates its channel assignment decision based on local information.
Distributed approaches can react faster to topology changes due to node
failures or mobility and usually introduce less protocol overhead since
communication with the CAS is not necessary. As a result, distributed
approaches are more suitable once the network is operational and running.
Distributed approaches can further be classified into static and dynamic, in
regard to the modus of channel switching. In dynamic approaches, channels can
be switched on a per-packet basis, whereas in static approaches radios stay on
a specific channel for a longer period of time. Static assignments have been
more in focus, since the channel switching time for current Institute of
Electrical and Electronics Engineers (IEEE) 802.11 hardware is in the order of
milliseconds which is two orders higher than the packet transmission time.
Recently, surveys of channel assignment algorithms have been presented which
cover certain aspects of the research field. The survey in [1] introduces the
problem and presents a couple of distributed algorithms and [2] gives a broad
introduction to centralized and distributed approaches. The survey herein is
focused on distributed approaches for peer- to-peer network architectures.
This report describes the problem formulation for channel assignment in WMNs
and the fundamental concepts and challenges of this research area. We present
different distributed channel assignment algorithms and characterize them
according to a set of classification keys. Since channel assignment algorithms
may change the connectivity and therefore the network topology, they may have
a high impact on routing. Therefore, we present routing metrics that consider
channel diversity and adapt better to the multi- radio multi-channel scenario
than traditional routing metrics designed for single channel networks. The
presented algorithms are discussed and compared focusing on practical
evaluations in testbed and network environments. The implementation for real
networks is a hard and labor-intensive task because the researcher has to deal
with the complexity of the hardware, operating system, and wireless network
interface drivers. As a result, frameworks emerged in order to simplify the
implementation process. We describe these frameworks and the mechanisms used
to help researchers implementing their algorithms and show their limitations
and restrictions
An Efficient Interference Aware Partially Overlapping Channel Assignment and Routing in Wireless Mesh Networks
In recent years, multi-channel multi-radio wireless mesh networks are considered a reliable and cost effective way for internet access in wide area. A major research challenge in this network is, selecting a least interference channel from the available channels, efficiently assigning a radio to the selected channel, and routing packets through the least interference path. Many algorithms and methods have been developed for channel assignment to maximize the network throughput using orthogonal channels. Recent research and test-bed experiments have proved that POC (Partially Overlapped Channels) based channel assignment allows significantly more flexibility in wireless spectrum sharing. In this paper, first we represent the channel assignment as a graph edge coloring problem using POC. The signal-to-noise plus interference ratio is measured to avoid interference from neighbouring transmissions, when a channel is assigned to the link. Second we propose a new routing metric called signal-to-noise plus interference ratio (SINR) value which measures interference in each link and routing algorithm works based on the interference information. The simulation results show that the channel assignment and interference aware routing algorithm, proposed in this paper, improves the network throughput and performance
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