IEX8175 RF Electronics
description
Transcript of IEX8175 RF Electronics
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IEX8175 RF Electronics
Avo Otstelekommunikatsiooni õppetool,
TTÜ raadio- ja sidetehnika [email protected]
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circuit-switchednetworks
(e.g. telephone)
communication networks
switchednetworks
broadcastnetworks
packet-switched networks
datagram networks
(e.g. Internet)
virtual circuit-switched networks(e.g. ATM)
Networks
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Layering
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4
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1 Füüsiline (ühendus)
Kanal
Võrk
Transport
Seanss
Esitlus
Rakendus Application
Presentation
Session
Transport
Network
Data link
Physical
SSL, WSP
RFC 791 IP,RFC 792 ICMP
TCP RFC 793, UDP RFC 768
WAE, HTTP, RFC821,822
ISO 8859-15
IEEE 802.11a
Cat5, RS-232D
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Lower three layers are hop-by-hop
Next two layers are end-to-end
Application
Transport
Network
Datalink
Physical
Application
Transport
Network
Datalink
Physical
Network
Datalink
Physical
Physical medium
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applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
networklink
physical
data
data
data
transport
transport
ack
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applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
networklink
physical
data
data
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datagram
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
source destination
M
M
M
M
Ht
HtHn
HtHnHl
M
M
M
M
Ht
HtHn
HtHnHl
message
segment
frame
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Telnet FTP
packetradio
coaxial cable
fiberoptic
HTTP
HTTPTelnet FTP
packetradio
coaxial cable
fiberoptic
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• The application knows the requirements best, place functionality as high in the layer as possible
• If the application can implement a functionality correctly, implement it at a lower layer only as a performance enhancement
• Think twice before implementing a functionality that you believe that is useful to an application at a lower layer
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Töökindlus
• Solution 1: make each step reliable, and then concatenate them
• Solution 2: end-to-end check and retry
L1
L2
L1
sender receiver
L1
L2
router
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Töökindluse tagamine
• The receiver has to do the check anyway!
• Thus, full functionality can be entirely implemented at the upper layer; no need for reliability from lower layers
• Is there any need to implement reliability at lower layers?
L1
L2
L1
sender receiver
L1
L2
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Time slots
Arr
ival
rat
e
tts
T
C
Temporarilybuffered
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Protokollidhttp://www.private.org.il/tcpip_rl.html
http://www.eix.co.uk/Ethernet/
ftp://ftp.prenhall.com/pub/esm/sample_chapters/cs/stallings/index.html