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CAP517 Mobile and ADHOC Networks

HOME-WORK 2

Mobile and ADHOC Networks

SUBMITTED TO:

MS GUrleen kaur

SUBMITTED BY:

vikas RANA

ROLL NO. 03

REG. NO. 7010070026

BCA (H) MCA

LOVELY PROFESSIONAL

UNIVERSITY

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PART A

1. Discuss routing in PRNET?

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ANSPacket radio was a technology that extended the conceptof packet switching (which evolved from point-to-point

communication metworks) to the domain of broadcast radio

networks. During the 1970s, the ALOHA project at the

University of Hawaii demonstrated the feasibility of usingthe broadcasting property of radios to send/receive data

packets in a single radio hop system. The ALOHA project

later led to the development of a multi-hop multiple-access

packet radio network (PRNET) under the sponsorship of the

Advanced Research Project Agency (ARPA) Unlike

ALOHA, PRNET permits multi-hop communications over a

wide geographical area. ARPA itself has a history in terms of

its name and roles.

Following are the types of routing in PRNET

Point-to-Point Routing

PRNETs support point-to-point communications through point-to-

point routing. Here, a packet originating at one part of the

network moves through a series of one or more repeaters until it

eventually reaches the final destination. This point-to-point

route is an ordered set of repeater addresses that is determined

by the mobile station. This station is the only element in thenetwork that has knowledge of the overall network connectivity,

that is, the network topology. With network topology

information, the mobile station computes the best point-to-point

route and distributes this information to all repeaters in the route

or directly to the source packet radio. This scheme was found to

be suitable for slow moving user terminals.

Broadcast Routing

Radio technology provides very good broadcasting properties.Broadcasting information to all radios in a network is equivalent

to flooding. To ensure that each packet radio only forwards a

packet once, each repeater has to maintain a list of packet

identifiers for previously broadcast packets that it recently had

received and forwarded.

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In broadcast routing, a packet radiates away from the source packet

radio in a wave-like fashion, that is, the packet ripples away

from the source. Although broadcasting is very robust (since a

packet will be received by every node in the non-partitioned

network), it is not efficient for two-party communications sinceall other nodes in the network must participate in the

transmission and reception of packets that are not intended for

them. Hence, when broadcast routing is used for point-to-point

communication, the destination host address is included in each

data packet. No specific routes are derived prior to data

transmission; hence, routing decisions are not centralized.

Packets will eventually reach the destination host if the network

is not partitioned. For fast moving user terminals, broadcast

routing was found to be useful as it avoids the need to processrapidly changing routes.

Packet Forwarding

The connectionless approach to packet forwarding requires some

background operation to maintain up-to-date network topology

and link information in each node. This means that as network

topology changes, the background routing traffic can be

substantial. This is commonly associated with broadcast routing,

where each packet carries sufficient routing information for it toarrive at the destination.

In the connection-oriented packet forwarding approach, however, an

explicit route establishment phase is required before data traffic

can be transported. This approach is commonly associated with

point-to-point routing, where each node in a route has a lookup

table for forwarding incoming packets to the respective outgoing

links. Hence, if a topology changes, a route re-establishment

phase is needed.

Impact of Mobility

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In a PRNET, all elements of the network can be mobile. Some move

relatively slowly (for example, the repeaters), and hence, a

topological change in the backbone network is not frequent. The

assumption made in a PRNET is that user terminals normally

move slowly enough such that the assigned point-to-point routesare valid for at least a few seconds before another route must be

chosen.

When the user rate of mobility is increased, point-to-point routing

may not be practical since most of the time will be spent in

computing alternate point-to-point routes instead of forwarding

the packets to their intended destinations. Under such

circumstances, very poor communication performance will be

observed. Broadcast routing is less affected by user mobilitysince the packets do not follow a specific point-to-point route.

Instead, every node is supposed to relay the packets, and hence,

the destination host will receive the packet eventually. There is,

therefore, no need to cope with rapidly changing routes in

broadcast routing under conditions of rapid host mobility.

However, broadcasting is power inefficient.

2. Explain PCS?ANSPersonal Communications Service orPCS is the namefor the 1900 MHz radio band used fordigitalmobile

phone services in Canada, Mexico and the United States. IS-

95(cdmaOne), GSM, and D-AMPS systems can be used on PCS

frequencies. The FCC, as well as Industry Canada, set aside the

frequency band of 1850-1990 MHz for mobile phone use in

1994, as the original cellular phone band at 800-894 MHz was

becoming overcrowded. Dual-band GSM phones are capable ofworking in both the 850 and 1900 MHz bands, although they are

incompatible with 900 and 1800 MHz European and Asian

systems. However, GSM "world phones" (some of which are

known as tri-band orquad-band phones, because they operate in

three or four different frequency bands, respectively) offered by

North American carriers support both European and domestic
http://en.wikipedia.org/wiki/Megahertzhttp://en.wikipedia.org/wiki/Digitalhttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Canadahttp://en.wikipedia.org/wiki/Mexicohttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/IS-95http://en.wikipedia.org/wiki/IS-95http://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/Digital_AMPShttp://en.wikipedia.org/wiki/Federal_Communications_Commissionhttp://en.wikipedia.org/wiki/Industry_Canadahttp://en.wikipedia.org/wiki/Cellular_frequencieshttp://en.wikipedia.org/wiki/Dual-bandhttp://en.wikipedia.org/wiki/Tri-bandhttp://en.wikipedia.org/wiki/Quad-bandhttp://en.wikipedia.org/wiki/Megahertzhttp://en.wikipedia.org/wiki/Digitalhttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Canadahttp://en.wikipedia.org/wiki/Mexicohttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/IS-95http://en.wikipedia.org/wiki/IS-95http://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/Digital_AMPShttp://en.wikipedia.org/wiki/Federal_Communications_Commissionhttp://en.wikipedia.org/wiki/Industry_Canadahttp://en.wikipedia.org/wiki/Cellular_frequencieshttp://en.wikipedia.org/wiki/Dual-bandhttp://en.wikipedia.org/wiki/Tri-bandhttp://en.wikipedia.org/wiki/Quad-band

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frequencies. Outside the USA, PCS is used to refer to GSM-

1900. In Hong Kong, PCS is used to refer to GSM-1800.

Sprint was the first company to set up a PCS network, which

was a GSM network in the Baltimore-Washingtonmetropolitan area. Eventually however, Sprint converted that

network to CDMA technology and sold the GSM

infrastructure to Omnipoint, which later became part ofT-

Mobile USA. Nowadays, the PCS frequencies have been

adopted for usage in most parts of the Americas.

PCS Architecture

Terminology of PCS

Radio Network

MS (Mobile Station) (or so-called mobile phone)

BS (Base Station)

Wired Transport Network
http://en.wikipedia.org/wiki/Hong_Konghttp://en.wikipedia.org/wiki/Sprint_Nextel_Corporationhttp://en.wikipedia.org/wiki/Baltimore-Washington_metropolitan_areahttp://en.wikipedia.org/wiki/Baltimore-Washington_metropolitan_areahttp://en.wikipedia.org/wiki/T-Mobile_USAhttp://en.wikipedia.org/wiki/T-Mobile_USAhttp://en.wikipedia.org/wiki/Americashttp://en.wikipedia.org/wiki/Hong_Konghttp://en.wikipedia.org/wiki/Sprint_Nextel_Corporationhttp://en.wikipedia.org/wiki/Baltimore-Washington_metropolitan_areahttp://en.wikipedia.org/wiki/Baltimore-Washington_metropolitan_areahttp://en.wikipedia.org/wiki/T-Mobile_USAhttp://en.wikipedia.org/wiki/T-Mobile_USAhttp://en.wikipedia.org/wiki/Americas

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MSC (Mobile Switching Center)

Mobility database attached with MSC

Mobile Station (MS)

Portable Handset, Mobile phone

Base Station (BS)

The radio coverage of a BS is called a cell

The BSs usually connect to wired core network via land

links or dedicated microwave links.

Communication Access Technology

FDMA Frequency Division Multiple Access TDMA Time Division Multiple Access

CDMA Code Division Multiple Access

3. Ad hoc network suffers from heterogeneity. Discuss this?

Heterogeneous communication interfaces in a real-world mobile ad

hoc network test bed. The aim is to provide an end-to-end

communication abstraction that hides heterogeneity. The anticipated

algorithm introduces features like backup routes and delay awarerouting to improve AODV's performance heterogeneity in Ad hoc

network comes in different flavors.

Sensor Network

Personal Area Network

Traditional Mobile Ad Hoc Network

Heterogeneity in mobile computing devices and application

scenarios complicates the development of collaborative software

systems. Heterogeneity includes disparate computing and

communication capabilities, differences in users' needs and

interests, and semantic conflicts across different domains and

representations. Heterogeneity in Mobile Devices

Devices differ in:

- Size

- Computational power

- Memory

- Disk

- Battery Capacity

Ad hoc device can act as server or service provider

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Some devices are more powerful, hence can be servers others

can be clients

Relay packets and also expel its own energy

Thus a mobile node must check its own well-being before

committing to relay packets on others behalf.

Wireless Ad Hoc Backhaul Network and different ways to access

the medium

IEEE 802.15 and Bluetooth

IEEE 802.11a/b/d/g/h/e/p

IEEE 802.16A

IEEE 802.20

PART - B

1. Differentiate between ETE and routing header?

ANS In PRNETs, a packet traverses over a chosen path hop-by-

hop and is acknowledged at every packet radio along the path.

Forwarding is accomplished via information read from the device

and tier tables, and from the packet headers.

ETE Header

The end-to-end header (ETE) is created by the source mobile

device/terminal, not the packet radio. It includes the source

device ID/address, which is used to update the packet radio's

device-to-packet radio mapping information, and the

destination device ID/address, which is used in packet

forwarding. The ETE header remains intact as the packet

transits toward the destination device.

Routing Header

In contrast to the ETE header, the routing header is created

by the source packet radio. The routing header encapsulates

the ETE header, since it is the routing header that the packet

radio will use to forward the packets. Note that the source

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packet radio ID, sequence number, and destination packet

radio ID remain intact throughout the packet's journey toward

the destination packet radio. The remaining fields are updated

by every intermediate packet radio in the route. Eventually,

the routing header is stripped at the destination packet radioand the ETE header is exposed. The packet is then delivered

to the destination device.

The Structure of a Routing Header

Routing Header Field Purpose

Source PR ID Acknowledgment

Sequence Number Acknowledgment

Previous PR ID Acknowledgment

Previous PR's transmit count Pacing

Transmitting PR ID Acknowledgment

Transmitting PR's transmit

count

Pacing

Next PR ID Forwarding/Pacing/Acknowledgment

Tier Alternate Routing

Destination PR ID Forwarding

2. Explain challenges in ad hoc wireless networks?

ANS challenges in ad hoc wireless networks are the followings

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1. Naming and addressing flexibility.

2. Mobility support for dynamic migration of end-users and

network devices.

3. Location services that provide information on geographic

position.4. Self-organization and discovery for distributed control of

network topology.

5. Security and privacy considerations for mobile nodes and open

wireless channels.

6. Decentralized management for remote monitoring and control.

7. Cross-layer support for optimization of protocol performance.

8. Sensor network features such as aggregation, content routing and

in-network Processing.

9. Cognitive radio support for networks with physical layeradaptation.

10. Economic incentives to encourage efficient sharing of

resources.

The major open problems are listed as:

Autonomous- No centralized administration entity is available to

manage the operation of the different mobile nodes.

Dynamic topology- Nodes are mobile and can be connected

dynamically in an arbitrary manner. Links of the network varytimely and are based on the proximity of one node to another node.

Device discovery- Identifying relevant newly moved in nodes and

informing about their existence need dynamic update to facilitate

automatic optimal route selection.

Bandwidth optimization- Wireless links have significantly lower

capacity than the wired links.

Limited resources -Mobile nodes rely on battery

power, which is a scarce resource. Also storage capacity and power

are severely limited.

Scalability- Scalability can be broadly defined as whether the

network is able to provide an acceptable level of service even in the

presence of a large number of nodes.

Limited physical security- Mobility implies higher security risks

such as peer-to- peer network architecture or a shared wireless

medium accessible to both legitimate network users and malicious

attackers.

Eavesdropping, spoofing and denial-ofservice attacks should be

considered.

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Poor Transmission Quality- This is an inherent problem of

wireless communication caused by several error sources that result

in

degradation of the received signal.

Ad hoc addressing- Challenges in standard addressing scheme tobe implemented.

Network configuration- The whole MANET infrastructure is

dynamic and is the reason for dynamic connection and

disconnection of

the variable links.

Topology maintenance- Updating information of dynamic links

among nodes in MANETs is a major challenge

3. PRNET consists of various devices. Discuss?

ANS PRNET consists of several mobile radio repeaters, wireless

terminals, and dedicated mobile stations. The role of a repeater is to

relay packets from one repeater to another, until the packets

eventually reach the destination host. The mobile station is present

to derive routes from one host to another. As network conditions

change (terminal movement, repeater failures or recovery, changes

in hop reliability, and network congestion state), routes are

dynamically reassigned by the station to satisfy minimum delaycriteria. Hosts and terminals attached to the PRNET are unaware of

the station's assignment and reassignment of communication routes.

DEVICES IN PRN

The network architecture of PRNETs , which comprises mobile

devices/terminals, packet radios, and repeaters. The static

station is optional

A radio repeater is a combination of a radio receiver and a radio

transmitter that receives a weak or low-level signal and retransmits

it at a higher level or higher power, so that the signal can cover

longer distances without degradation. This article refers to

professional, commercial, and government radio systems

Wireless terminals attached to PRNET this is unaware ofstations assignment and reassignment of routes.

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The mobile station (MS) comprises all user equipment

and software needed forcommunication with a mobile network.

The mobile station refers to global system connected to the mobilenetwork, i.e. mobile phone or mobile computerconnected using

a mobile broadband adapter. This is the terminology of2G systems

like GSM. In the 3G systems, mobile station (MS) is now referred

as user equipment (UE).

Packet radio is a form ofpacket switching technology used to

transmit digitaldata via radio orwireless communications links. It

uses the same concepts of data transmission via Datagram that arefundamental to communications via the Internet, as opposed to the

older techniques used by dedicated orswitched circuits

ARCHITECTURE OF PACKET RADIO NETWORK

The interface of a data terminal to a packet radio
http://en.wikipedia.org/wiki/Computer_softwarehttp://en.wikipedia.org/wiki/Communicationhttp://en.wikipedia.org/wiki/Cellular_networkhttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Mobile_broadbandhttp://en.wikipedia.org/wiki/2Ghttp://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/3Ghttp://en.wikipedia.org/wiki/User_equipmenthttp://en.wikipedia.org/wiki/Packet_switchinghttp://en.wikipedia.org/wiki/Digitalhttp://en.wikipedia.org/wiki/Datahttp://en.wikipedia.org/wiki/Radiohttp://en.wikipedia.org/wiki/Wirelesshttp://en.wikipedia.org/wiki/Data_linkhttp://en.wikipedia.org/wiki/Datagramhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Circuit_switchinghttp://en.wikipedia.org/wiki/Computer_softwarehttp://en.wikipedia.org/wiki/Communicationhttp://en.wikipedia.org/wiki/Cellular_networkhttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Mobile_broadbandhttp://en.wikipedia.org/wiki/2Ghttp://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/3Ghttp://en.wikipedia.org/wiki/User_equipmenthttp://en.wikipedia.org/wiki/Packet_switchinghttp://en.wikipedia.org/wiki/Digitalhttp://en.wikipedia.org/wiki/Datahttp://en.wikipedia.org/wiki/Radiohttp://en.wikipedia.org/wiki/Wirelesshttp://en.wikipedia.org/wiki/Data_linkhttp://en.wikipedia.org/wiki/Datagramhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Circuit_switching

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The user computer interfaced to radio via terminal network

controller (TNC) LSI based therefore bulky architecture radio that

handles layer 1 TNC and Radio constitute packet to layer 3

functionalities radio within itself due to Now a laptop integrates

packet VLSI

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