• If for example the cellular network uses GSM (Global System for Mobile) technology with a frequency reuse cluster of 7 then six of the base stations have 72 voice traffic channels a[r]
(1)Access Network Design
Access Network Design
Continued
Continued
David Tipper
Associate Professor
Associate Professor
Department of Information Science and Telecommunications
University of Pittsburgh Slides 8
http://www.sis.pitt.edu/~dtipper/2110.html http://www.sis.pitt.edu/~dtipper/2110.html
TELCOM 2110 2
A top down network design project approach should follow three phases:
– Conceptual Model
• Objectives, Requirements, Constraints
– Logical Model
• Technology, network graph, node location, etc
– Physical Model
• Specific hardware/software implementations (e.g., wiring diagram, repeater locations, etc.)
(2)TELCOM 2110 3
• Access Networks Technology Choices • For circuit switched voice traffic
– STM, ATM – constant bit rate service (CBR), MPLS CBR emulation
• For packet data traffic
– STM, ATM, SMDS, X.25, Frame Relay, Token Ring, FIDDI, Ethernet, cable modem, dSL, wireless
technology, etc
• Choice depends on cost and features needed • Given technology selection and logical design –
create physical design (select equipment, etc)
Example
• Consider a cellular network in a downtown urban environment as shown below with distances in 1Km The nodes represent base stations and the hub node a base station controller co-located with a base station We choose STM technology for connecting the nodes with T1s or multiple of T1s
2 1 1 IBM
M S C
B S 7 B S 2
B S 3 B S 4 B S 1
S D
Centillion1400 B ay Ne twork sE THER
RS232C PCC ARD P*8x 50OOO130A O N6RSTLINKINSACTALM
PWRALMFAN0 FAN1 PWR 0PWR1ALM
BSC
B S 2 B S 3
B S 4 B S 1
S D
Centillion 1400 B ay Ne twork s ETHERRS 232C
PC C ARD P*8x 50OOO130A O N6RSTLINKINSACTALM
PWRALMFAN0 FAN1 PWR 0PWR1ALM
BSC
S D
Centillion 1400 B ay Ne twork s
ETHERRS 232C PC C ARD P*8x 50OOO130A O N6RSTLINKINSACTALM PWRALMFAN0 FAN1 PWR 0PWR1ALM
(3)TELCOM 2110 5 Example
• If for example the cellular network uses GSM (Global System for Mobile) technology with a frequency reuse cluster of then six of the base stations have 72 voice traffic channels and base station has 64 traffic channels (Nodes 0-5 have 72, Node 6, 64, Nodes and have 72 – part of a different reuse cluster)
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TELCOM 2110 6
Normalizing the weight of each individual node to a T1 capacity (T1 can handle 24 traffic channels Nodes 0-5 and 7,8 have weight 72/24 = 3, Node has weight 64/24 = 2.667
Links are considered are 6T1 link => W = Cost = 400 + 50 d
Applying E-W algorithm
Initialize with every node having a direct link cost
Ci0= [450, 500, 450, 470.7, 511.8, 500, 511.8, 541.4]
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Example
(4)TELCOM 2110 7 Tradeoff(i)=minjCost(Ni,NJ) -Cost(Comp(Ni),Center)
Tradeoff(1) = 450 - 450 = Tradeoff(2) = 450- 500 = -50 Tradeoff(3) = 450-450 = Tradeoff(4) = 450 – 470.7 = -20.7 Tradeoff(5) = 450 - 512 = 62 Tradeoff(6) = 450 – 500 = -50 Tradeoff(7) = 450 – 512 = -62 Tradeoff(8) = 450 – 541 = -91 Pick to merge with either or Pick since
Checking capacity w7+w8= ≤W =
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Example
Tradeoff(i)=minjCost(Ni,NJ) -Cost(Comp(Ni),Center) Tradeoff(1) = 450 - 450 =
Tradeoff(2) = 450- 500 = -50 Tradeoff(3) = 450-450 = Tradeoff(4) = 450 – 470.7 = -20.7 Tradeoff(5) = 450 - 512 = 62 Tradeoff(6) = 450 – 500 = -50
Tradeoff(7) = 450 – 512 = -62 not allowed Tradeoff(8) = 450 – 512 = -62 not allowed Pick to merge with either or
Pick
Checking capacity w4+w5= ≤W =
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(5)TELCOM 2110 9 Example
Tradeoff(i)=minjCost(Ni,NJ)
-Cost(Comp(Ni),Center) Tradeoff(1) = 450 - 450 = Tradeoff(2) = 450- 500 = -50 Tradeoff(3) = 450-450 =
Tradeoff(4) = 450 – 470.7 = -20.7 not allowed Tradeoff(5) = 450 – 470.7 = -20.7 not
allowed
Tradeoff(6) = 450 – 500 = -50
Tradeoff(7) = 450 – 512 = -62 not allowed Tradeoff(8) = 450 – 512 = -62 not allowed Pick to merge with
Checking capacity w2+w1= ≤W = Similarly will have merge with
In next iteration w3+w6= 5.66 ≤W =
Final topology as shown
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TELCOM 2110 10
Example
• Once topology known move to physical design
• Need to select equipment: BS,
BSC, interfaces, cables etc.
• Price vendor equipment and link options from service provider
– Equipment Vendors: Lucent, Nortelnetworks, Siemens, Nokia, Ericsson, Alcatel, etc
• Service provider may
implement link as a Add/Drop Multiplexer (ADM) drop off of a higher capacity link
(6)TELCOM 2110 23
• Need to connect the numerous wires (could be hundreds) to the electronics.
• A large cable bundle is very heavy and would be hard to move around.
• We use wiring closet/patch panels to provide an way to connect the wiring bundles to the
electronics. • Location
– Accessibility & Security
– Environmental concerns (heating/cooling, power)
Wall Jack In Wall
Wiring
PC
Fiber Patch Panel
Backbone Switch
Fiber Run
UTP P Panel
Switch
Fiber Patch Panel
(7)TELCOM 2110 26 Summary
• Top Down Network Design
– Conceptual Model – Objectives
• Business Goals – Technical Goals
– Requirements
• Business, Technical (availability, delay, bandwidth, security, etc.,)
– Constraints