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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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CAP517 Mobile and ADHOC Networks
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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CAP517 Mobile and ADHOC Networks
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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CAP517 Mobile and ADHOC Networks
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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CAP517 Mobile and ADHOC Networks
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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CAP517 Mobile and ADHOC Networks
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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CAP517 Mobile and ADHOC Networks
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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CAP517 Mobile and ADHOC Networks
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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CAP517 Mobile and ADHOC Networks
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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CAP517 Mobile and ADHOC Networks
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