A Demonstration of a Management Tool
for Assessing Channel Quality Information
in Wireless Testbeds?
Apostolos Apostolaras, Vasileios Miliotis, Nikolaos Giallelis,
Dimitris Syrivelis, Thanasis Korakis, and Leandros Tassiulas
Department of Computer and Communication Engineering
University of Thessaly
Centre for Research & Technology Hellas (CERTH)
Abstract. The gradually growing need for testbed use so as networking
algorithms to be validated in real environment, has given rise to optimal
utilization of testbed resources. Towards this direction, we present a new
management tool that is used for assessing channel quality information
in wireless testbed deployments. NITOS Connectivity Tool retrieves data
concerning link quality measurements, for providing testbed users with
useful information about choosing nodes that occasionally satisfy the
requirements (link quality, connectivity) needed, for their experiments.
NITOS connectivity tool is a full-fledged managerial tool that exploits
testbed utilization by letting testbed users have a complete view about
testbed’s nodes. This tool allows a more sophisticated way to optimally
choose network resources of a testbed.
Lab’s website: “http://nitlab.inf.uth.gr”
This demo paper is related to the paper entitled “Towards Maximiz-
ing Wireless Testbed Utilization using Spectrum Slicing” accepted for
publication on TridentCom 2010.
A testbed experiment deployment needs node allocation that should satisfy cer-
tain topology and link quality requirements. Moreover, the erewhile link quality
information gives a testbed user the advantage of properly evaluate the observed
experiment/algorithm performance. Since NITOS testbed deployment is not RF
isolated, the link quality between any pair of nodes may unexpectedly vary at
any point in time due to external interference. For this reason the static distribu-
tion approach, that is used in RF isolated wireless testbeds, is not efficient
for these deployments. Therefore, there is a growing need for updated informa-
tion in terms of densely measurements of link quality, that will bring in a long
term, a more accurate channel quality estimation.
?The research leading to these results has received funding from the European Com-
munity’s Seventh Framework Programme (FP7/2007-2013) under grant agreement
2Apostolos Apostolaras et Al.
2 NITOS Connectivity Tool
In this demo, we will present a management tool for assessing channel quality
information. The tool was developed for NITOS testbed and measures channel
connectivity among wifi interfaces. NITOS is a wireless testbed, located in Volos,
Greece with 15 nodes, each node equipped with two wifi interfaces. It is deployed
on Computer & Communication Dept. University of Thessaly building. NITOS
testbed topology is depicted on the left part of Fig. 1. Although the NITOS
connectivity tool was developed on NITOS testbed, it can be adapted for use
on any wireless testbed, with minor modifications. NITOS connectivity tool is a
NITOS scheduler part, which is used for resource allocation on NITOS testbed.
We have implemented NITOS connectivity tool, based on TLQAP , which
is a protocol, that is used to assess interconnection topology and link quality
by estimating packet delivery ratio (PDR) in downlink communication at each
node’s wifi interface for all requested channel, rate and transmission power com-
binations. Specifically, TLQAP builds a measurement history log and creates a
channel utilization profile, and stores that information in a database that is used
for link quality information retrieval by NITOS connectivity tool.
NITOS Connectivity Tool is comprised of three entities: a web interface, a
database and a set of .dot scripts. The web interface is the interactive tool that
an experimenter uses to choose testbed nodes for some time and it is depicted
on the right side of Fig. 1. A user enters the NITOS Connectivity tool through
NITLAB’s wiki http://nitlab.inf.uth.gr. Now, the user has the ability to navigate
through testbed’s site and select “Scheduler → Topology-Connectivity” menu.
Fig. 1. NITOS Connectivity Tool
Specifically, at first the user selects through web interface, by using a drop-
down menu, a sender node that he/she wants to check and might want to use in
testbed. Then the user is prompted to select an operating frequency among IEEE
802.11 communication standards 802.11a/b/g and selects the operating rate.
Then, he/she goes to the final step where he submits his/her query concerning
the link quality of a certain node. In sequence, the tool seeks to a database
where the channel quality results are stored and retrieves the information that
Title Suppressed Due to Excessive Length3 Download full-text
Fig. 2. Link Quality for node 4
corresponds to the particular query. This information with the use of .dot files
that are used to depict graphs are presented to the users. On Fig. 2, the downlink
communication link quality for node 4 among its neighboor nodes is illustrated.
Each node is indicated by a circle and the PDR of each link is reported upon
edges that indicate link connectivity to certain node’s wifi interfaces. Those
interfaces are reported with their MAC addresses, with an arrow showing to the
node where they belong.
In this demo paper we present a wireless connectivity tool that enables better
utilization of testbed under effective resource exploitation. In particular, users
can select nodes and observe link quality by navigating through a web interface
that is built as an extension tool of NITOS scheduler and retrieves information
from TLQAP. Thus, users can choose those nodes that satisfy their experiment
1. ORBIT-Radio Grid. http://www.orbit-lab.org.
2. UTH NITLab. http://nitlab.inf.uth.gr.
3. A. C. Anadiotis, A. Apostolaras, D. Syrivelis, T. Korakis, L. Tassiulas, L. Rodriguez,
I. Seskar, M. Ott. Towards Maximizing Wireless Testbed Utilization using Spectrum
Slicing. In Accepted for publication in TridentCom 2010, 18-20 May 2010, Berlin,
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Siracusa, H. Liu, M. Singh. “Overview of the ORBIT Radio Grid Testbed for
Evaluation of Next-Generation Wireless Network Protocols”.
5. Dimitris Syrivelis, Angelos-Christos Anadiotis, Apostolos Apostolaras, Thanasis Ko-
rakis, Leandros Tassiulas. Tlqap: A topology and link quality assessment protocol
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