Wireless in Local Loop System
corDECT is an advanced,
field proven, Wireless Access System developed by Midas Communication Technologies
and the Indian Institute of Technology, Madras, in association with Analog Devices
Inc., USA. corDECT provides a complete wireless access
solution for new and expanding telecommunication networks with seamless integration
of both voice and Internet services. It is the only cost-effective Wireless Local
Loop (WLL) system in the world today that provides simultaneous toll-quality voice
and 35 or 70 kbps Internet access to wireless subscribers.
corDECT is based on the DECT standard specification from the European Telecommunication
Standards Institute (ETSI). In addition, it incorporates new concepts and innovative
designs brought about by the collaboration of a leading R & D company, a renowned
university, and a global semiconductor manufacturer. This alliance has resulted
in many breakthrough concepts including that of an Access Network that segregates
voice and Internet traffic and delivers each, in the most efficient manner, to
the telephone network and the Internet respectively, without the one choking the
The corDECT Wireless Access System
(WAS) is designed to provide simultaneous circuit-switched voice and medium-rate
Internet connectivity at homes and offices.
Conceptual Access System
In this conceptual
model, there is a Subscriber Unit (SU) located at the subscriber premises. The
SU has a standard two-wire interface to connect a telephone, cordless phone, or
modem. It also provides direct (without modem) Internet connectivity to a standard
PC, using either a serial port (RS-232 or USB) or Ethernet. The access system
allows simultaneous telephone and Internet connectivity. The SU's are connected
to an Access Centre (AC) using any convenient technology like wireless, plain
old copper, coaxial cable, optical fibre, or even power lines.
The AC must be scalable, serving as few as 200 subscribers and as many as 2000
subscribers. In urban areas, the AC could be located at a street corner, serving
a radius of 700 m to 1 km. This small radius in urban areas is important for wireless
access, in order to enable efficient reuse of spectrum. When cable is used, the
small radius ensures low cost and higher bitrate connectivity. However in rural
areas, the distance between the AC and the SU could easily be 10 km even go up
to 25 km in certain situations.
The AC is
thus a shared system catering to multiple subscribers. The voice and Internet
traffic to and from subscribers can be concentrated here and then carried on any
appropriate backhaul transport network to the telephone and Internet networks
respectively. At the AC, the telephone and Internet traffic is separated. The
telephone traffic carried to the telephone network on E1 links using access protocols
such as V5.2. the Internet traffic from multiple subscribers is statically multiplexed,
taking advantage of the bursty nature of the Internet traffic, and carried to
the Internet network.
As use of Voice-over-IP (VoIP) grows, voice traffic from
subscriber traffic could also be sent to the Internet, gradually making the connectivity
to the telephone network redundant. However, for connecting to the legacy telephone
network, the voice port of the AC may be required for some time to come. An AC
could also incorporate switching and maintenance functions when required.