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The Direct Internet Access System (DIAS) enables
the convergence of voice and data by exploiting the existing
copper access network infrastructure. It is an advanced cost
effective solution for Telecom Operators and Internet Service
Providers (ISP's). DIAS provides high speed for permanent (leased
line), internet access and telephone services on a single copper
pair, to residential and corporate subscribers.
DIAS SYSTEM CONFIGURATION
The system consists of two sub-systems:
i) IAN (Integrated Access Node)
The IAN subrack can hold up to six line cards in addition to
a switch card, an E1 interface card and a power supply card.
The line cards can be any valid combination of the following
two types.
- Basic rate Digital Subscriber Line (BDSL) card supporting
12 ports of 144 Kbps each.
- High bit-rate Digital Subscriber Line (HDSL) card supporting
4 ports of up to 2 Mbps.
The equipment separates voice and data to be passed on to the
Public Switched Telephone Network (PSTN) and Internet respectively.
The IAN is connected to the PSTN either via E1 (V5.2) line (figure:1)
or 2 wire using SMUX (Subscriber Multiplexer) (figure:2). Internet
connectivity from IAN is via E1 lines/Nx64 Kbps channels.
The IAN has two E1 ports for carrying voice connections, one used
for cascading voice traffic when multiple IAN's are daisy chained
and the other for connecting voice traffic to the Exchange.
Two data E1 ports connect the IAN to the Internet/ISP. Optionally,
IANs enable the setting up of Nx64 Kbps switched call on the E1
port to the exchange and then to the ISP router. The ethernet
port on the IAN side can be used for connecting to the router
or for cascading internet data.
ii) DIAS Terminals or "Subscriber Units"
The Subscriber Units are located at the subscriber premises. The
system supports two types of units:
- Basic Rate Digital Subscriber Unit (BDSU) that supports
a maximum data rate of 144 kbps and provides leased line internet
access at this rate.
- High Bit Rate Digital Subscriber Unit (HDSU) that supports
a maximum data rate of upto 2 Mbps.
BDSU and HDSU are connected to the IAN located at the kerb/exchange
using twisted-pair copper wire. The line code used between IAN
and subscriber units is 2B1Q. Both the units have voice and data
ports.
The BDSU has 10 Base-T Ethernet port for data and an analog voice
telephone port. The HDSU has a 10 Base-T Ethernet port for data
and 0/4/8 analog voice telephone ports.
ADVANTAGES OF THE DIAS SYSTEM:
- High speed permanent (leased line) internet access on existing
copper pair.
- Simultaneous availability of both voice and internet services
to the subscriber.
- Aggregating the long duration data calls at the IAN, thereby
decongesting the trunk network of the Basic Service Operators
(BSO).
- Additional revenue source from internet services to existing
BSO with incremental capital expenditure.
- Flexibility in deployment in low density and high density
areas.
- DIAS deployed with WLL & FILL products having common NMS,
provides ideal low cost & high performance network options
(as in figure:3).
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