WIRELESS TECHNOLOGY

INTRODUCTION

Communication Medium o Acoustical

o Optical

o Mechanical

o Electrical

wired

wireless

Wireless versus Mobile

Private versus Public Types

Wireless

Mobile

Cellular/Personal

Wireless

Mobile

Cellular

DEFINITION

DEFINITION

WPAN WIRELESS PERSONAL AREA NETWORK

NFC Near Field Communication (close proximity, eg: smartphones)

SEMACODE Code scanner

SENSOR wireless sensor

GPS Global Positioning System

RFID Radio Frequency Identification, used to track item in store

M2M Machine 2 Machine using wireless

WLAN WIRELESS LOCAL AREA NETWORK

WIFI Wireless in Fidelity

WWAN WIRELESS WIDE AREA NETWORK

GPRS- General Packet Radio Service (2G)

EDGE - Enhanced Data rates for GSM Evolution or Enhanced GPRS

3G 3rd Generation Cellular (telephone, mobile internet, video calls etc)

HSPA - High Speed Packet Access (HSPA+ can reach up to 168 Mbps / 22 Mbps)

Advantages

Cost independent of terrain and distance

Suitable for incremental capacity enhancement, i.e. flexible planning

Reduced maintenance effort, i.e. better reliability

Ease of installation and maintenance, i.e. suitability for temporary or emergency services

Dynamic use of medium, i.e trunking capability

Limited mobility

Suitable for multiple operators, i.e. service liberalisation

Limitation

Capacity limited by frequency allocation, i.e. cellular design is expensive

Margin has to be provided for multipath propagation effect, i.e. expensive for normal urban

application

Power source required at terminal end

ADVANTAGES & LIMITATIONS

Wireless equivalent of Ethernet

Unlicensed band: ISM Band (2.4 GHz) Industrial, Scientific & Medical

Benefits : Mobility, Installation speed and simplicity Installation

flexibility, Reduced cost of ownership, Scalability

Base stations (APs): Connect to Ethernet

Laptop Cards: Drivers for Windows, Linux, MacOS

Typical range is up to 300m

Technology

Spread spectrum (wideband) RF

Use more spectrum for better reliability

Frequency Hopping (FH) Spread Spectrum

Direct-Sequence (DS) Spread Spectrum

Standard developed by IEEE and ETSI BRAN

Wireless LAN

ETSI - European Telecommunications Standards Institute BRAN Broadband Radio Access Network IEEE - Institute of Electrical and Electronics Engineers

802.11

provides 1 or 2 Mbps transmission in the 2.4 GHz band

using either FH or DS

802.11a

provides up to 54 Mbps in the 5GHz band

50 ft range

802.11b

provides 11 Mbps transmission (with a fallback to 5.5, 2

and 1 Mbps) in the 2.4 GHz band.

uses only DS

150 ft range

802.11g

provides 54 Mbps in the 2.4 GHz band.

50 ft range

802.11n

provides 300+ Mbps in the 2.4/5 GHz band.

175 ft range

Use MIMO technology

IEEE Standard for Wireless LAN

WIRELESS LAN PERFORMANCE

The performance depends on several factors:

Distance between WLAN devices (AP and NICs/PC)

Transmission power levels typical 30mW

Building and home materials

Radio frequency interference

Signal propagation

Antenna type and location

WIRELESS LAN PERFORMANCE

WIRELESS CHANNEL FREQUENCY

WIRELESS LAN SECURITY

WLAN are open to attacks. The following known attacks are known to be effective: Passive Attacks

1 Dictionary based attacks 2 Cracking the WEP key

Active attacks 1 Authentication Spoofing 2 Message Injection 3 Message Modification 4 Message Decryption

WIRELESS LAN SECURITY

To make the WLANs reliable the following security goals were considered:

Limited access to a WLAN set time based access control at the AP for each workstation Authentication Part of IEEE 802.11 protocol Encryption Part of IEEE 802.11 protocol Traffic filtering advance configuration set at the AP to filter type of traffic that flows through

AUTHENTICATION 802.11 specify two authentication mechanisms:

1) Open system authentication 2) Shared key authentication

Open system authentication A client needs an SSID for successful Association. Any new client that comes in an area is provided with an SSID. This is equivalent to no security.

WIRELESS LAN SECURITY

Shared system authentication The client cannot authenticate himself if he doesn't have the WEP (Wired Equivalent Protocol) shared secret key. WEP protocol is used for encryption.

WIRELESS LAN SECURITY

Other higher level authentication used are: AES - Advanced Encryption Standard - Key Length of 128, 192, 256 bit - AES is considered to be un-crackable by most Cryptographers TKIP - Temporal Key Integrity Protocol - Initially referred to as WEP2, is an interim solution that fixes the key reuse problem of WEP EAP - Extensible Authentication Protocol - provides port-based access control and mutual authentication between clients and access points via an authentication server - use of digital certificates

WIRELESS LAN Service Set Identifier (SSID)

SSID is something that you should configure when setting up a wireless

access point

SSID is a label that distinguishes one wireless LAN from another

Typically contains up to 32 alphanumeric characters, which are case

sensitive

Wireless client must have the same SSID as the one put in the access point.

Default SSID Issues : Access points are preconfigured with a default name

for the SSID based on the vendor. E.g Cisco use tsunami

PREPARING WLAN SETUP

Pre-requisite

Physical

Access Point

Client (PC with wireless / Laptop)

Internal cabling

Configuration

SSID

Authentication

Security / firewall

Filtering

PREPARING WLAN SETUP

INTEGRATED WIRELESS ACCESS POINT

Network Controller (as well as radius/AAA)

AAA Authentication, Authorization, Accounting

TROUBLESHOOTING IN WIRELESS ENVIRONMENT

Troubleshooting is to determine:

Connectivity between wireless client & AP Check the SSID setting at the wireless client, is it match with SSID of the AP? Check the authentication protocol used, is it WEP, AES, TKIP etc ipconfig to check own ip address & the gateway ping to check reachability to the gateway from wireless client

Connectivity to internet DNS lookup to check on the DNS server reachability ipconfig /all to check on DNS setting

Slow access to internet ping to check on latency from wireless client to AP and to internet server Traceroute to identify which portion in the network that cause the slowness Check on the AP processing capability, is it capable to handle all protocols (PPP, routing, NAT etc)