Cnap Upgrade Davv 1 2
-
Upload
navya-srini -
Category
Documents
-
view
220 -
download
0
Transcript of Cnap Upgrade Davv 1 2
-
7/31/2019 Cnap Upgrade Davv 1 2
1/15
Oxford University Press 2007. All rights reserved. 1
Data Dissemination and Broadcasting
Systems
Lesson 01
Communication Asymmetry and
Broadcast Architecture
-
7/31/2019 Cnap Upgrade Davv 1 2
2/15
Oxford University Press 2007. All rights reserved. 2
Communication Asymmetry
Intrinsically asymmetric Mobile
communication between the mobiledevice and static computer system
Device allocated a limited bandwidth Because of a large number of devices
-
7/31/2019 Cnap Upgrade Davv 1 2
3/15
Oxford University Press 2007. All rights reserved. 3
Communication Asymmetry
Bandwidth in the downstream from the
server to device much larger than theone in the upstream from the device toserver
Because mobile devices have limitedpower resources
Faster data transmission rates for long
intervals of time need greater powerdissipation from the devices
-
7/31/2019 Cnap Upgrade Davv 1 2
4/15
Oxford University Press 2007. All rights reserved. 4
Communication asymmetry in uplink
and downlink in a mobile network
-
7/31/2019 Cnap Upgrade Davv 1 2
5/15
Oxford University Press 2007. All rights reserved. 5
GSM networks data transmission
Rates go up to a maximum of 14.4 kbps
for both uplink and downlink
Symmetric communication
Only used for voice communication
-
7/31/2019 Cnap Upgrade Davv 1 2
6/15
Oxford University Press 2007. All rights reserved. 6
i-mode for many applications
Used for voice, multimedia transmission,
Internet access, voice communication
Base station provides downlink 384 kbps
Uplink from the devices restricted to 64kbps
Asymmetric communication
-
7/31/2019 Cnap Upgrade Davv 1 2
7/15
Oxford University Press 2007. All rights reserved. 7
The characteristics in wireless signals
Interference and time-dispersion
Signal distortion and transmission errors
at the receiver end
Lead to path loss and signal fading,which cause data loss
Greater access latency compared to
wired networks
-
7/31/2019 Cnap Upgrade Davv 1 2
8/15
Oxford University Press 2007. All rights reserved. 8
The characteristics in wireless signals
Data loss has to be taken care of by
repeat transmissions
Transmission errors have to be corrected
Taken care of by appending additionalbits, such as the forward error correction
bits
-
7/31/2019 Cnap Upgrade Davv 1 2
9/15
Oxford University Press 2007. All rights reserved. 9
The characteristics in Mobile
communication
Mobile devices also have low storage
capacity (memory)
Cannot hoard large databases
Accessing the data online not only has alatency period (is not instantaneous) but
also dissipates bandwidth resources of
the device
-
7/31/2019 Cnap Upgrade Davv 1 2
10/15
Oxford University Press 2007. All rights reserved. 10
Broadcasting
Corresponds to unidirectional (downlink
from the server to the devices)
Unicast communicationUnicast means
the transmission of data packets in acomputer network such that a single
destination receives the packets
-
7/31/2019 Cnap Upgrade Davv 1 2
11/15
Oxford University Press 2007. All rights reserved. 11
Broadcasting or application distribution
service
This destination generally the one which
has subscribed to the service
Mobile TVan example of unidirectional
unicast mode of broadcasting Each device receives broadcast data
packets from the service providers
application distribution system
-
7/31/2019 Cnap Upgrade Davv 1 2
12/15
Oxford University Press 2007. All rights reserved. 12
Broadcasting or application distribution
service
Applicationdistribution system
broadcasts data of text, audio, or videoservices
-
7/31/2019 Cnap Upgrade Davv 1 2
13/15
Oxford University Press 2007. All rights reserved. 13
A broadcasting architecture
-
7/31/2019 Cnap Upgrade Davv 1 2
14/15
Oxford University Press 2007. All rights reserved. 14
Summary
GSM symmetric and voice only
Mobile communication asymmetric in
general
Limited device capability Device memory, energy and uplink and
downlink bandwidths
Broadcast architecture
-
7/31/2019 Cnap Upgrade Davv 1 2
15/15
Oxford University Press 2007. All rights reserved. 15
End of Lesson 01
Communication Asymmetry and
Broadcast Architecture