Access Network Planning and Technologies
Part1 structure of Access Network
Conception of Access Network
Access Network(exchange) is the subscriber part of the telecommunications
network. The basic idea of telecommunication is the exchange of information.
•Voice
•text
•data
•image
•video
If you are a telecommunications service provider and you have set up you first
switch. You just need to link the customer premises equipment(CPE) to you
witch with a pair of copper conductors .
Simple interconnection of subscribers to exchange
Structure of the Access Network
DP1
2000 pairs
400 pairs
DP2
DP3
SCP
To other SCPs
PCP
EXCHANGE
Part2
New Technologies in the Access Network
Limitation of the copper network
•limited bandwidth and there are problems in overcoming.
•Inflexibility: both in time and types of service provisioning.
•Reliability is limited.
•Installation time is long.
•Possible cable damages and maintenance costs were high.
•Difficult to manage
•Loop length limitations(~ 5km)
•Has problem of security
•Uneconomical in remote
•Prone to electromagnetic interference
New technologies in the copper Access Network
Name Meaning
DSL
Digital
Data
Connection
Distance
Rate
type
to exchange
160kb/s
Symmetrical
~5 km
Subscriber
Application
ISDN series, voice,
data communication
line
HDSL
SDSL
ADSL
VDSL
High Data
2Mb/s
Symmetrical
4-5km
No POTS, E1, LAN/
Rate Digital
WAN, Internet Service
Subscriber line
access
Single Line
2Mb/s
Symmetrical
3-4km
Same as HDSL+POTS
Digital Sub-
Work at home,
scriber line
internet access
Asymmetric
Downstream
Asymmetrical
Digital Sub-
2-8Mb/s, Up-
emand, remote LAN access
scriber line
stream 128kb/s-768kb/s
interactive multimedia
Very High
Downstream 13-
Data Rate
52Mb/s,
Digital Sub-
Upstream 1.5-
scriber Line
2.3Mb/s
Asymmetrical
3-6km
0.3-1.5km
Internet access, video on d-
Same as ADSL
HDTV
Fiber based new technologies in the Access Network
Methods of deployment of fiber
•Fiber to the Curb(FTTC)
•Fiber to the Building(FTTB)
•Fiber to the home/office(FTTH/FTTO)
Fiber in the loop architectures
•Point-to-point
•Point-to-multipoint/star
•Tree
•Ring
Technological options
1. PDH(plesiochronous digital hierarchy)
•
fiber optic cabinet
•
PON(passive optical network)
•
AON(active optical network)
2. SDH(synchronous digital hierarchy)
Basic PON system components
• OLT(optical line terminal)
•
Splitter
•
ONU(optical network unit)
Typical implementation of PONs
ONU
Management
Up to 4 PONs
ONU
1
ONU
Switch
2
OLT
3
Capacity: 4B-120B
4
Splitting up to 32
Capacity: OLT 1920B, PON 480B
B: 64Kb bearer channel
Advantages of PON/AON
• Sharing of fiber and equipment as in case of PONs
•Increase in range at the cost of an additional active component(splitter)
•High flexibility in structures
•Higher capacity
•Management
Future of PON systems
ATM-PON(APON):
One fiber is passively split up to 64 times.
Serve more customers.
Can savings 20%-40% over circuit based access systems.
Future of PON systems
ATM-PON(APON):
One fiber is passively split up to 64 times.
Serve more customers.
Can savings 20%-40% over circuit based access systems.