Chapter 7- Mobile and Wi-Fi Networks

Taking signals on and off the air Connections to other networks

Need to manage spectrumManaging and billing for services

Connections to: voice mail, collaboration, instant messaging

Taking Signals on and off AirwavesCellular base stations• 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

Wi-Fi access points• 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)

EnodeB EnodeB

EnodeB

SGW* MME*

PGW*

* SGW – Serving gateway* MME – Mobility management entity* PGW – Packet data network gateway Bearer channels for user data Signaling channels

Evolved packet core

Radio access network

LTE• Modified for data• All IP• 30 to 40% more capacity

Core, Base Stations and Increasing Capacity

Functions in the core– 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

Aggregation network

Corenetwork

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.

AccessNetworks

Backhaul consists of access and aggregation networks

Spectrum

• What is it?• Wavelength

– Low frequencies - longer wavelengths– Higher frequencies - shorter wavelengths

Lower frequency wavelengths

Higher 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 Enterprisesà Laptops & tablet computersà Cabling costs à Moves adds and change savingsà Need for computers in common areasà Monitoring inventory and patients in hospitals

I know where the beds are.

Key 802.11 Standards

• 802.11n• Range• Capacity• Speed - 100

Mbps• Why these

matter

• MIMO• multiple

input/multiple output

• Multiple antennas• Multiple streams of

traffic

Security• What can go wrong?

– Complexity vs. ease of administration• Intrusion detection

– To detect unauthorized users– Shared passwords

• WPA2 (Wi-Fi Protected Access 2) 802.11i subset of 802.11i– AES (Advanced Encryption Standard) – 128 bit level of encryption - more sophisticated algorithm

• 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)

Cincinnati Headquarters or the cloud

Miami

Kansas City

Dallas

Management console• Statistics on usage• Information on congestion• Reports on security• Identities of allowed users

Mobile Services Summary• Wi-Fi and LTE architecture• Key aspects of 4th generation LTE Service

– IP protocols– LTE– More capacity on Backhaul

• Spectrum• Handhelds & user experiences• Enterprise Wi-Fi networks• Key Wi-Fi standards

– 802.11b, g & a and n– Improved antennas - MIMO

• Security • Access points