Wireless and Mobile

CommunicationsCourse Instructor:

Dr. Rabia Noor Enam

Text Book: Wireless Communications and Networks by William Stallings, Second Edition

Reference Book: Wireless Communications: Principles And Practice, by Rappaport Theodore S., Second Edition.

Week No. Topic Chapter No.

1 Introduction to Wireless Network Technology, History and Types of wireless networks, Basic wireless network architectures

2 Cellular Wireless Networks 1034 Wireless LAN Technologies 1356 Wi-Fi and IEEE 802.11 Wireless LAN standards 14

7 Bluetooth and IEEE 802.15 Standards 158 Satellite Communications 99 MID TERM

10 Spread Spectrum 71112 Antennas & Propagations 51314 Mobile IP 121516 Revision & Final Quiz

Course Outline

Week No

ContentsPage No in

manual1 Introduction to Wireless Network and its technologies 01-08

2Configure the Cisco LINKSYS Wireless-G Broadband Router for Wireless Infrastructure Mode

09-15

3Configure the Cisco LINKSYS Wireless-G Broadband Router for Wireless Ad-hoc Mode

16-19

4 Interconnecting Wired LAN with Wireless LAN 20-225 Configure LINKSYS Broadband Router as DHCP server 23-276 Authentication Methods, Wireless Equivalent Privacy (WEP) 28-357 Revision8 Pre-Mid Viva9 MID TERM

10 MAC Address Filtering 36-4111 IP Filtering 42-4612 Configuring Access Point as a Wireless Client of a Wireless Broadband Router 47-5213 NAT/PAT Support by the Wireless Broadband Router 53-6114 Configure Voice over IP (VoIP) 62-6615 Configure Syslog and NTP 67-6916 Final Viva

Week Wise Lab Outline 

Wireless network

•The term “Wireless Networks” refers to any kind of networking that does not involve cables.

•It is a technique that helps to save the cost of cables for networking in specific premises in their installations.

•But the major advantage of wireless networks is the mobility and roaming of its users

•The transmission system is usually implemented and administrated via radio waves where the implementation takes place at physical level.

Wireless History

Radio invented in the 1880s by Marconi Many sophisticated military radio systems were developed during and after WW2 Cellular has enjoyed exponential growth since 1988, with almost 5 billion users worldwide today Ignited the wireless revolution Voice, data, and multimedia ubiquitous Use in third world countries growing

rapidly Wifi also enjoying tremendous success

and growth Wide area networks (e.g. Wimax) and

short-range systems other than Bluetooth (e.g. UWB) less successful

Ancient Systems: Smoke Signals, Carrier Pigeons, …

Wireless Communication

History

AMPS: Advance mobile phone System• Developed by Bell Labs, • Officially introduced in Pakistan in 1990. discontinued by October 2004.

NMT: Nordic Mobile Telephone• Basic difference number of channels and frequency bands• Both use FDD and FDMA

GSM: Global System for Mobile Communications D-AMPS: Digital-AMPS• Both use TDMA

IS-95: Interim Standard • Uses CDMA

UMTS: Universal Mobile Telecommunications System• Advanced GSM moved to W-CDMA Also Called UMTS• UMTS supports maximum theoretical data transfer rates of 42 Mbits/s • Advanced IS-95 moved to CDMA 2000

TD-SCDMA: Time Division Synchronous Code Division Multiple Access

3GPP:3rd Generation Partnership Project

LTE: Long Term Evolution• The LTE specification provides downlink peak rates of 300 Mbit/s,

uplink peak rates of 75 Mbit/s• QoS provisions permitting a transfer Latency of less than 5 ms in

the radio access network

Future !!• Next-generation Cellular• Wireless Internet Access• Wireless Multimedia• Sensor Networks • Smart Homes/Spaces• Automated Highways• In-Body Networks• All this and more …

Standards Interacting systems require

standardization

Companies want their systems adopted as standardAlternatively try for de-facto

standards

Standards are determined by TIA/CTIA in USIEEE standards often adoptedProcess fraught with inefficiencies

and conflicts

Worldwide standards determined by ITU-T In Europe, ETSI is equivalent of

IEEE

Spectrum Regulation Spectrum a scarce public resource,

hence is allocated Spectral allocation in US controlled by

FCC (commercial) or OSM (defense) Some spectrum set aside for universal

use Worldwide spectrum controlled by ITU-

R

The Electromagnetic Spectrum

Types of Wireless Networks

Usually types of wireless networks are defined on the bases of

• Their size/range

• Their number of machines

• The speed of data transfer.

 

Wireless Network in terms of coverage

area Wireless PAN – Personal

area network Wireless Personal Area Networks

Wireless LAN – Local Area Network

Wireless MAN – Metropolitan Area Networks

Wireless WAN- Wide Area Network

Notice the IEEE Standards numbers in each case!!

Wireless PANWireless Personal Area Networks

Such networks interconnect devices in small premises usually within the reach of a person for example

Invisible infra red light Bluetooth radio interconnects Headphone to a laptop by the virtue of WPAN. Wi-Fi into customer electronic devices

Wireless LAN

The simplest wireless distribution method that is used for interlinking two or more devices providing a connection to wider internet through an access point. (100m range)

LAN’s data transfer speed is typically 10 Mbps for Ethernet and 1 Gbps for Gigabit Ethernet.

LANs could accommodate as many as hundred or even one thousand users.

OFDM or other spread-spectrum technologies give clients freedom to move within a local coverage area while remaining connected to the LAN.

Wireless MAN

The wireless network that is used to connect at high speed multiple wireless LANs that are geographically close (situates anywhere in a few dozen kilometers).

The network allows two or more nodes to communicate with each other as if they belong to the same LAN.

The set up makes use of routers or switches for connecting with high-speed links such as fiber optic cables.

WiMAX described as 802.16 standard by the IEEE is a type of WMAN.

Wireless WAN WAN is the wireless network that usually covers

large outdoor areas. The speed on such network depends on the cost

of connection that increases with increasing distance.

The technology could be used for interconnecting the branch offices of a business or public internet access system.

Developed on 2.4GHz band these systems usually contain access points, base station/gateways and wireless bridging relays.

The most commonly available WAN is internet.

The point of the classification is not to partition each technology into a separate bin, but to highlight the high-level differences within each use case. For Example

• Some devices have access to a continuous power source; others must optimize their battery life at all costs.

• Some require Gbit/s+ data rates; others are built to transfer tens or hundreds of bytes of data.• Some applications require always-on connectivity, while others are delay and latency

tolerant. These and a large number of other criteria are what determine the original characteristics of each type of network.

Architecture of Wireless Networks

The architecture of a network defines the protocols and components necessary to satisfy application requirements. Seven-layer Open System Interconnect (OSI) Reference Model, developed by the International Standards Organization (ISO) specifies a complete set of network functions. These functions reside within each network component.

Architecture of Wireless Networks

The architecture of a network defines the protocols and components necessary to satisfy application requirements. Seven-layer Open System Interconnect (OSI) Reference Model, developed by the International Standards Organization (ISO) specifies a complete set of network functions. These functions reside within each network component. The basic difference in

OSI (Or TCP/IP) model of a wired and wireless network lies on the lower three layers

Layer 7—Application layer: Establishes communications among users and provides basic communications services such as file transfer and e-mail. Examples of software that runs at this layer include Simple Mail Transfer Protocol (SMTP), HyperText Transfer Protocol (HTTP) and File Transfer Protocol (FTP).Layer 6—Presentation layer: Negotiates data transfer syntax for the application layer and performs translations between different data formats, if necessary. For example, this layer can translate the coding that represents the data when communicating with a remote system made by a different vendor.Layer 5—Session layer: Establishes, manages, and terminates sessions between applications. Wireless middleware and access controllers provide this form of connectivity over wireless networks. If the wireless network encounters interference, the session layer functions will suspend communications until the interference goes away.Layer 4—Transport layer: Provides mechanisms for the establishment, maintenance, and orderly termination of virtual circuits, while shielding the higher layers from the network implementation details. In general, these circuits are connections made between network applications from one end of the communications circuit to another (such as between the web browser on a laptop to a web page on a server). Protocols such as Transmission Control Protocol (TCP) operate at this layer.Layer 3—Network layer: Provides the routing of packets though a network from source to destination. This routing ensures that data packets are sent in a direction that leads to a particular destination. Protocols such as Internet Protocol (IP) operate at this layer.Layer 2—Data link layer: Ensures medium access, as well as synchronization and error control between two entities. With wireless networks, this often involves coordination of access to the common air medium and recovery from errors that might occur in the data as it propagates from source to destination. Most wireless network types have a common method of performing data link layer functions independent of the actual means of transmission.Layer 1—Physical layer: Provides the actual transmission of information through the medium. Physical layers include radio waves and infrared light.

Open System Interconnect (OSI) Reference Model

Architecture of Wireless Networks

Each layer of the OSI model supports the layers above it. Usually Wireless networks are directly implement only on the lower layers of the model.

The actual transmission of data occurs at physical layer. Frames that are sent by the physical layer actually contain frames from all higher layers. At the destination, each layer passes applicable frames to higher layers to facilitate the protocol between peer layers. A wireless NIC, for example, implements the data link layer

and physical layer functions. The lower layers often appear transparent to the layers above.

For example, TCP operating at the transport layer establishes connections with applications at a distant host computer, without awareness that lower layers are taking care of synchronization and signaling.

However In some cases, attention to higher layers is necessary to ensure that applications operate effectively in the presence of wireless network impairments.

Performance Fundamentals of

Wireless Networks

Each and every type of wireless technology has its own set of constraints and limitations.

However, all communication methods have a maximum channel capacity.

Claude E. Shannon’s mathematical model determines channel capacity, regardless of the technology in use.

C=BW×log2(1+S/N)

Performance Fundamentals of

Wireless Networks

In General following 3 parameters affect the performance of a wireless network

Bandwidth Signal Power Modulation Technique

Few factors that may affect the performance of a wireless network:

Amount of distance between receiver and sender Amount of background noise in current location Amount of interference from users in the same network

(intra-cell) Amount of interference from users in other, nearby

networks (inter-cell) Amount of available transmit power, both at receiver and

sender Amount of processing power and the chosen modulation

scheme

Bandwidth Unlike wired network, radio communication uses a shared medium:

radio waves or electromagnetic radiation. Both the sender and receiver must agree on the specific frequency range over which the communication will occur. For example, the 802.11b and 802.11g standards both use the 2.4–2.5 GHz band across all WiFi devices.

Usually local government determines the frequency range and its allocation. (For eg Federal Communications Commission (FCC) in US). Different countries often assign different spectrum ranges to the same wireless technology.

Size of the assigned frequency range is an important performance factor. As Shannon’s model shows, the overall channel bit rate is directly proportional to the assigned range. Ex: going from 20 to 40 MHz of bandwidth can double the channel data

rate, which is exactly how 802.11n is improving its performance over earlier WiFi standards!

Finally, it is also worth noting that not all frequency ranges offer the same performance. Low-frequency signals travel farther and cover large areas (macrocells),

but at the cost of requiring larger antennas and having more clients competing for access.

On the other hand, high-frequency signals can transfer more data but won’t travel as far, resulting in smaller coverage areas (microcells) and a requirement for more infrastructure.

Signal Power Signal-power-to-noise-power, S/N ratio, or SNR is an important

limiting factor in all wireless communication. It is a measure that compares the level of desired signal to the level of background noise and interference. The larger the amount of background noise, the stronger the

signal has to be to carry the information. Other devices may generate unwanted interference. For example, A microwave oven operating at 2.5 GHz may overlap with the

frequency range used by WiFi, creating cross-standard interference.

Other WiFi devices, such as your neighbors' WiFi access point, and even your coworker’s laptop accessing the same WiFi network, also create interference for your transmissions.

Also the distance affect the signal power. Attenuation increases with distances

To achieve the desired data rate where interference is present, we can either increase the transmit power, thereby increasing the strength of the signal, or decrease the distance between the transmitter and the receiver—or both, of course. This can produce Near-far effect

Modulation Modulation is the process of varying one or more properties of a

periodic waveform, called the carrier signal, with a modulating signal that typically contains information to be transmitted.

Modulation is the process of conveying a message signal, for example a digital bit stream or an analog audio signal, inside another signal that can be physically transmitted.

A modulator is a device that performs modulation.  Demodulator  is a device that performs the inverse of modulation. A modem (from modulator–demodulator) can perform both operations.

The combination of the alphabet and the symbol rate is what then determines the final throughput of the channel. For example: Receiver and sender can process 1,000 pulses or symbols per second

=1,000 baud. If Each transmitted symbol represents 2-bit alphabet (e.g., : 00, 01,

10, 11). Then the bit rate of the channel is 1,000 baud × 2 bits per symbol, or

2,000 bits per second. But if each symbol represent 4-bit alphabet (eg 0000, 0001, 0010,

0011, 0100,-------1111) Then the bit rate of the channel is 1,000 baud × 4 bits per symbol, or

4,000 bits per second.

Modulation• The aim of Analog modulation is to transfer an analog baseband (or low pass) signal,

for example an audio signal or TV signal, over an analog band pass channel at a different frequency, for example over a limited radio frequency band or a cable TV network channel.

• The aim of Digital modulation is to transfer a digital bit stream over an analog band pass channel, for example over the public switched telephone network (where a band pass filter limits the frequency range to 300–3400 Hz) or over a limited radio frequency band.

• The choice of the modulation algorithm depends on the available technology, computing power of both the receiver and sender, as well as the SNR ratio

Wireless devicesWireless technology defines the electronic devices that communicate in air

without cables using radio frequency signals. On general the wireless devices are:

Wireless Router Wireless routers accepts an incoming Internet connection and sends

the data as RF signals to other wireless devices that are near to the router. A network set up with a wireless router is called as a Wireless Local Area Network (WLAN).Many routers have built-in security features such as firewalls that help protect devices connected to the router against malicious data such as computer viruses.

A wireless router is used in many houses to connect their computers to the Internet.

Wireless Adapters Wireless adapters are hardware devices that are installed inside

computers which enables wireless connectivity. If a computer does not have a wireless adapter, it will not be able to connect to a router in order to access the Internet.

Wireless Repeater A wireless repeater is a wireless networking device that is used to

extend the range of a wireless router. A repeater receives wireless signals and amplifies the strength of the signals, and then re-emits them. The strength of the signal can be increased by placing a repeater between the router and the computer connected to the router.

Wifi Devices AP = Access Point – L2 bridge (802.1d)

between wired (802.3) & wireless (802.11)

STA = Station – 802.11 NIC (PHY in form of PC Card, USB, PCI, etc.)Mini PCI for Laptops and Embedded

WiFi PC cards

Examples of Wireless Networks

Broadcast radio Radio broadcasting is a one-

way wireless transmission over radio waves intended to reach a wide audience.

A broadcast sends information over long distances at up to two megabits/Sec (AM/FM Radio).Examples:

Cable radio,Local wire television networks, Satellite radio, Internet radio via streaming media on the Internet.

Broadcast radio

Microwave Communication

Microwave wireless communication is an effective type of communication,

Mainly Uses radio waves, and the wavelengths of radio waves are measured in centimeters. In this communication, the data or information can be transferred using two methods. One is satellite method and another one is terrestrial method.

The main disadvantage of microwave signals is, they can be

affected by bad weather, especially rain.

Satellite Communication

Orbits:LEO: Low Earth Orbit.MEO: Medium Earth OrbitGEO: Geostationary Earth Orbit

• Satellite Communication Cover very large areas (ex: GPS)

• Data can be transmitted though a satellite, that orbit 22,300 miles above the earth..• There are about 750 satellite in the space, • Transmission delay is about 0.3 sec.

• Stations on the earth send and receive data signals from the satellite with different frequency ranging and with a transmission speed of 1Mbps to 10Mbps • Satellite up links (4, 11 and 20 Ghz) and down links (6,

14 and 30Ghz)

Infrared wireless Communication

Infrared wireless communication communicates information in a device or systems through IR radiation . IR is electromagnetic energy at a wavelength that is longer than

that of red light. IR cannot be travelled through obstacles in an infrared system, but

can be inhibited by light. Transmission is possible between two points limited to a range and line of sight.

The normal frequency of IR broadcast system is 100 GHz to 1,000 THz with a limited speed ranges from 100 Kbps to 16 Mbps (on average1 Mbps).

For a successful infrared communication, a photo LED transmitter and a photo diode receptor are required. The LED transmitter transmits the IR signal in the form of non visible light, that is captured and saved by the photoreceptor.

The source and destination can be Mobile phones, TVs, security systems, laptops etc

Wifi• Wi-Fi is a low power wireless LAN communication, that is used by various

electronic devices like smart phones, laptops, etc.• In  this setup, a router or AP works  as a communication hub wirelessly. These

networks allow users to connect only within close proximity to a router.• WiFi is very common in networking applications which affords portability

wirelessly. • These networks need to be protected with passwords for the purpose of

security, otherwise it will access by others

ZigBee/ IEEE 802.15.4 Low-Rate WPAN Data rates of 20, 40, 250 Kbps Support for large mesh networking

or star clusters Support for low latency devices CSMA-CA channel access Very low power consumption Frequency of operation in ISM bands ZigBee is used in Commercial

Applications like sensing and monitoring applications

Mobile Communication

System A cellular network or mobile network is a

wireless network distributed over land areas called cells, each served by at least one fixed-location transceiver, known as a cell site or base station.

In a cellular network, each cell uses a different set of frequencies from neighboring cells, to avoid interference and provide guaranteed bandwidth within each cell.

.

When joined together these cells provide radio coverage over a wide geographic area. This enables a large number of portable transceiver (mobile phones) to communicate with each other and with fixed networks, via base stations, Even if some of the transceivers are moving through more than one cell during transmission.

Bluetooth Technology• Bluetooth is a wireless PAN technology standard for exchanging data over

short distances (using short-wavelength UHF radio waves in the ISM band from 2.4 to 2.485 GHz) from fixed and mobile devices

• Invented by telecom vendor Ericsson in 1994• Bluetooth operates at frequencies between 2400 and 2483.5 MHz • Bluetooth uses a radio technology called frequency-hopping spread spectrum.

(FHSS) • Bluetooth divides transmitted data into packets, and transmits each packet on

one of 79 designated Bluetooth channels. Each channel has a bandwidth of 1 MHz.

Ad-Hoc Networks Peer-to-peer communications

No backbone infrastructure or centralized control. Does not rely on a pre existing infrastructure, such as routers in wired networks or access points in managed (infrastructure) wireless networks.

Routing can be multihop. Topology is dynamic. Fully connected with different link

Eg: WSN and MANETs Open Challenges

Fundamental capacity region Resource allocation (power, rate, spectrum, etc.) Routing