Sakthi PURA Project: Facilitating Rural Connectivity

Sakthi PURA project in Pollachi, which is aimed at providing
tele-education, healthcare and other information/content services to outlying
villages, as part of the PURA (Provision of Urban Amenities in Rural Areas) is
an initiative championed by the President of India. Nachimuthu Polytechnic
College (NPTC) and Mahalingam College of Engineering and Technology (MCET), are
the implementing agencies for Sakthi PURA Pollachi.

The content origination for the PURA network is from a studio in
Nachimuthu Polytechnic College, located in MCET campus, Pollachi. The studio is
connected by means of cable to the 30m transmission tower in the campus.
Connectivity is required to be established to identified remote villages (four,
in the initial phase), which are located at distances of up to 20 km from the
nodal center. The links should support data, voice and video services with QOS
management feature. A minimum of 2 Mbps throughput should be supported at
distances of up to 25 km. Finally, the infrastructure should operate in
unlicensed bands, without requiring a wireless license.

Uneven, hilly terrain and very tall trees make LOS visibility
difficult at distances beyond 10 km. Supporting the throughput requirement at
long distances and realizing the necessary QOS on the link, especially for
narrowband video, were additional challenges.

Design of the solution comprised three parts. First, Proxim
Wireless Corp's Tsunami MP.11 Base Station Unit and Subscriber Units,
operating in the unlicensed band of 2.4-2.48 GHz band, were selected as the
appropriate equipment which could meet the performance and reliability
requirements of the project. As the link had to be robust over long distances,
it was decided to use high gain external antennas at both BSU and SU locations
in each link. Third, an RF survey was conducted for each link to establish
feasibility of the link, together with derivation of antenna height and gain
required for BSU and SU deployment.

Following the design of the links, implementation was taken up.
60° sector coverage panel antennas (17 dBi gain) were chosen for the BSUs and
mounted on the transmission tower at the nodal center for each link. Narrow Base
Towers (NBTs) of the required height were set up in each remote location. For
the farthest location-Arasampalayam, at 23 km from the nodal center-a 27 dBi
gain external antenna was chosen for the SU located there. At the near
location-Kanchampatti, at 6 km-a 24 dBi gain antenna was used with the SU.

Links were successfully established with Kanchampatti and
Arasampalayam. The links were tested for stability and QOS performance
subsequently for a week before it was being commissioned for operational
transmissions.

Team DQ

maildqindia@cybermedia.co.in