Transcript Chapter

Chapter 7- Mobile and Wi-Fi
Networks
Taking signals on and off the air
Connections to other networks
Need to manage spectrum
Managing and billing for services
Connections to: voice mail, collaboration, instant messaging
Taking Signals on and off Airwaves
Cellular base stations
Wi-Fi access points
• Base station & antenna
• Compatibility with Air interfaces –
LTE, 3G
• Translates air interfaces to
landline protocols & vice versa
• Connections to mobile core wired
or microwave backhaul
• Access point & antenna
• Compatibility with 802.11a,b,c n
and other Wi-Fi protocols
• Translates Wi-Fi protocols to
Ethernet LAN protocols & vice
versa
• Wired connection to LAN
backbone
• Security functions
Fourth Generation
Architecture Long Term Evolution (LTE)
LTE
• Modified for data
• All IP
• 30 to 40% more capacity
Evolved packet core
PGW*
SGW*
MME*
EnodeB
EnodeB
EnodeB
Radio access network
* SGW – Serving gateway
* MME – Mobility management entity
* PGW – Packet data network gateway
Bearer channels for user data
Signaling channels
Core, Base Stations and Increasing
Capacity
Functions in the core
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Databases for: roaming, billing, voice mail
Security
Signaling
Connections to other mobile networks, the
PSTN and the Internet
Keeping track of traffic & congestion
Balancing traffic between base stations if
there's congestion
• Adding capacity
– Add more cell sites
– Upgrade to higher, newer
protocols – 3G & 4G
– Add more powerful orthogonal
frequency division multiplexing
(OFDM) antennas
Functions in base stations
– Translating between the radio
frequency wireless signals and the
wireline backhaul network
– Connections to the backhaul network
Aggregation & Access in Backhaul Networks
Backhaul consists of
access and
aggregation networks
Aggregation
network
Core
network
Access
Networks
Controllers for 2nd, 3rd and 4th
generation services at the edge of
the core. 4th generation security,
other services and connections to the
Internet & public switched network in
the core.
Spectrum
• What is it?
• Wavelength
– Low frequencies - longer wavelengths
– Higher frequencies - shorter wavelengths
Higher frequency wavelengths
Lower frequency wavelengths
Pre – 4th Generation Air Interfaces
• AT&T & T-Mobile
– HSPA+ (High speed packet access plus)
– AT&T installing LTE
• Verizon, Sprint, China Mobile & MetroPCS
– LTE
– TD-LTE (China Mobile trialing)
• Sprint Nextel
– Changing from WiMAX to TD-LTE
• What is the impact of 4G on Internet access? In two or
three years 4G will reach speeds of 100 Mb per second.
Mobile devices - Multimode versus
Multi-band
• Multi-mode on the same
device
– WCDMA
– GSM
– LTE
• Multi-band on the same
device
– 700 megahertz (MHz) & 1.8
gigahertz (GHz)
– 2.4 GHz & 5 GHz Wi-Fi
What is Wi-Fi?
• A wireless 802.11 Ethernet standard
– Wi-Fi (Wireless fidelity) certification
• Why standards matter
• The downside of standards
Portability in Enterprises
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Laptops & tablet computers
Cabling costs
Moves adds and change savings
Need for computers in common areas
Monitoring inventory and patients in hospitals
I know
where the
beds are.
Key 802.11 Standards
Standard
Top Speed
Achievable
Speed
802.11b
11 megabits
per second
5 megabits per
second
3
2.4 gigahertz
802.11a
54 megabits
per second
24 megabits
per second
24
5 gigahertz
802.11g
54 megabits
per second
12 to 24
megabits per
second
3
2.4 gigahertz
•802.11n
• Range
• Capacity
• Speed - 100 Mbps
• Why these
matter
No. of
Channels
•MIMO
• multiple
Frequency
Band
input/multiple
output
• Multiple antennas
•Multiple streams of
traffic
Security
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What can go wrong?
– Complexity vs. ease of administration
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Intrusion detection
– To detect unauthorized users
– Shared passwords
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WPA2 (Wi-Fi Protected Access 2) 802.11i subset of 802.11i
– AES (Advanced Encryption Standard)
– 128 bit level of encryption - more sophisticated algorithm
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AAA authentication, authorization and accounting for remote user access
Security appliances with advanced capabilities
802.11 Infrastructure
Wireless controller
Managing Wireless Local Area Networks (WLANs)
Internet
Cincinnati
Headquarters
or the cloud
Management console
• Statistics on usage
• Information on congestion
• Reports on security
• Identities of allowed users
Internet
Internet
Mobile Services Summary
• Wi-Fi and LTE architecture
• Key aspects of 4th generation LTE Service
– IP protocols
– LTE
– More capacity on Backhaul
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Spectrum
Handhelds & user experiences
Enterprise Wi-Fi networks
Key Wi-Fi standards
– 802.11b, g & a and n
– Improved antennas - MIMO
• Security
• Access points