CN-II ASSIGNMENT:02

Q.1. Discuss Ad-Hoc VS Cellular network.

Parameters	Cellular network	Ad Hoc network
Network routing	Centralized, all the traffic goes through the Base Station	Distributed, No centralized system such as Base station needed
Switching Type	Circuit Switching	Packet Switching
Number of Hops	single hop type	Multiple hops
Topology	Star	Mesh
Application	Designed and developed for voice traffic	Designed to meet best effort data traffic requirements
Cost and time for installation	Higher cost and takes more time for deployment	Lower cost and does not take more time for deployment
Call drops	Low call drops during mobility due to seamless connectivity across region	Higher breaks in the path during mobility
Network maintenance	requires periodic maintenance and hence it is costly.	nodes are self organising and hence it is less costly.
Frequency re-use	It utilizes same frequency channels in the nearby cells with proper RF planning and antenna placement. This is known as static frequency re-use.	Dynamic frequency re-use is employed using carrier sense mechanism.
Bandwidth (BW) mechanism	The allocation of BW is guaranteed and easy.	The allocation of BW is based on shared channel using complex MAC algorithms.
Technologies	IS-95, IS-136, GSM, Mobile WiMAX, CDMA, LTE	WLAN 802.11e

Q.2. What do you mean by Ad-Hoc network ? Explain its features and advantages .
Ans:- An ad hoc network refers to a network connection established for a single session and does not require a router or a wireless base station.

For example, if you need to transfer a file to your friend's laptop, you might create an ad hoc network between your computer and his laptop to transfer the file. This may be done using an Ethernet crossover cable, or the computers' wireless cards to communicate with each other. If you need to share files with more than one computer, you could set up a mutli-hop ad hoc network, which can transfer data over multiple nodes.

Basically, an ad hoc network is a temporary network connection created for a specific purpose (such as transferring data from one computer to another). If the network is set up for a longer period of time, it is just a plain old local area network (LAN).

How to set up Ad Hoc network

Features

Ad hoc networks are useful when you need to share files or other data directly with another computer but don't have access to a Wi-Fi network.
More than one laptop can be connected to the ad hoc network, as long as all of the adapter cards are configured for ad-hoc mode and connect to the same SSID (service state identifier). The computers need to be within 100 meters of each other.
If you are the person who sets up the ad hoc network, when you disconnect from the network, all the other users are also disconnected. An ad hoc network is deleted when everyone on it disconnects—which can be good or bad, depending on your view; it's truly a spontaneous network.
You can use an ad hoc wireless network to share your computer's internet connection with another computer.

Advantages

The advantages of an ad hoc network include:

Separation from central network administration.
Self-configuring nodes are also routers.
Self-healing through continuous re-configuration.
Scalability incorporates the addition of more nodes.
Mobility allows ad hoc networks created on the fly in any situation where there are multiple wireless devices.
Flexible ad hoc can be temporarily setup at anytime, in any place.
Lower getting-started costs due to decentralized administration.
The nodes in ad hoc network need not rely on any hardware and software. So, it can be connected and communicated quickly.

Q.3. Explain MAC & Routing protocol.
Ans:-MAC PROTOCOL
The Media Access Control (MAC) data communication Networks protocol sub-layer, also known as the Medium Access Control, is a sub-layer of the data link layer specified in the seven-layer OSI model. The medium access layer was made necessary by systems that share a common communications medium. Typically these are local area networks. The MAC layer is the "low" part of the second OSI layer, the layer of the "data link". In fact, the IEEE divided this layer into two layers "above" is the control layer the logical connection (Logical Link Control, LLC) and "down" the control layer The medium access (MAC).

Following Protocols are used by Medium Access Layer :

ALOHA : ALOHA is a system for coordinating and arbitrating access to a shared communication channel. It was developed in the 1970s at the University of Hawaii. The original system used terrestrial radio broadcasting, but the system has been implemented in satellite communication systems. A shared communication system like ALOHA requires a method of handling collisions that occur when two or more systems attempt to transmit on the channel at the same time.

In the ALOHA system, a node transmits whenever data is available to send. If another node transmits at the same time, a collision occurs, and the frames that were transmitted are lost. However, a node can listen to broadcasts on the medium, even its own, and determine whether the frames were transmitted.

Carrier Sensed Multiple Access (CSMA) : CSMA is a network access method used on shared network topologies such as Ethernet to control access to the network. Devices attached to the network cable listen (carrier sense) before transmitting. If the channel is in use, devices wait before transmitting. MA (Multiple Access) indicates that many devices can connect to and share the same network. All devices have equal access to use the network when it is clear.

Even though devices attempt to sense whether the network is in use, there is a good chance that two stations will attempt to access it at the same time. On large networks, the transmission time between one end of the cable and another is enough that one station may access the cable even though another has already just accessed it. There are two methods for avoiding these so-called collisions, listed here :

CSMA/CD (Carrier Sense Multiple Access/Collision Detection) : CD (collision detection) defines what happenswhen two devices sense a clear channel, then attempt totransmit at the same time. A collision occurs, and bothdevices stop transmission, wait for a random amount oftime, and then retransmit. This is the technique used to access the 802.3 Ethernet network channel.

This method handles collisions as they occur, but if the bus is constantly busy, collisions can occur so often that performance drops drastically. It is estimated that network traffic must be less than 40 percent of the bus capacity for the network to operate efficiently. If distances are long, time lags occur that may result in inappropriate carrier sensing, and hence collisions.

CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) : In CA collision avoidance), collisions areavoided because each node signals its intent to transmitbefore actually doing so. This method is not popular becauseit requires excessive overhead that reduces performance.

ROUTING PROTOCOL

A routing protocol specifies how routers communicate with each other, distributing information that enables them to select routes between any two nodes on a computer network. Routing algorithms determine the specific choice of route. Each router has a prior knowledge only of networks attached to it directly

A routing protocol uses software and routing algorithms to determine optimal network data transfer and communication paths between network nodes. Routing protocols facilitate router communication and overall network topology understanding.

A routing protocol is also known as a routing policy.

There are different types of protocols of routing.
· Routing information protocols (RIP)
· Interior gateway routing protocol (IGRP)
· Open shortest path first (OSPF)
· Exterior gateway protocol (EGP)
· Enhanced interior gateway routing protocol (EIGRP)
· Border gateway protocol (BGP)
· Intermediate system-to-intermediate system (IS-IS)

Routing information protocols (RIP)

RIP (Routing Information Protocol) is a forceful protocol type used in local area network and wide area network. RIP (Routing Information Protocol) type is categorized interior gateway protocol within the use of distance vector algorithm. Routing information protocols defined in 1988. It also has version 2 and nowadays both versions are in use. Technically it is outdated by more sophisticated techniques such as (OSPF) and the OSI protocol IS-IS.

Interior gateway routing protocol (IGRP)

It is distance vector IGRP (Interior gateway Protocol) make-believe by Cisco. Router used it to exchange routing data within an independent system. Interior gateway routing protocol created in part to defeat the confines of RIP (Routing Information Protocol) in large networks. It maintains multiple metrics for each route as well as reliability, MTU, delay load, and bandwidth. The maximum hop of EIGRP is 255 and routing updates are transmitting 90 seconds. It measured in classful routing protocol, but it is less popular because of wasteful of IP address space.

Open shortest path first (OSPF)

Open Shortest Path First (OSPF) is an active routing protocol used in internet protocol. Particularly it is a link state routing protocol and includes into the group of interior gateway protocol. Open Shortest Path First (OSPF) operating inside a distinct autonomous system. The version 2 of Open Shortest Path First (OSPF) defined in 1998 for IPv4 then the OSPF version 3 in RFC 5340 in 2008. The Open Shortest Path First (OSPF) most widely used in the network of big business companies.

Exterior Gateway Protocol (EGP)

The absolute routing protocol for internet is exterior gateway protocol which is specified in 1982 by Eric C. EGP (Exterior Gateway Protocol) initially expressed in RFC827 and properly specified in RFC 904 in 1984.The Exterior Gateway Protocol (EGP) is unlike distance vector and path vector protocol. It is a topology just like tree.

Enhanced interior gateway routing protocol (EIGRP)

Enhanced Interior Gateway Routing Protocol (EIGRP) based on their original IGRP while it is a Cisco proprietary routing protocol. It is a distance-vector routing protocol in advance within the optimization to lessen both the routing unsteadiness incurred after topology alteration, plus the use of bandwidth and processing power in the router which support enhanced interior gateway routing protocol will automatically reallocate route information to IGRP (Enhanced Interior Gateway Routing Protocol) neighbors by exchanging the 32 bit EIGRP (Enhanced Interior Gateway Routing Protocol) metric to the 24 bit IGRP metric. Generally optimization based on DUAL work from SRI which assured loop free operation and offer a means for speedy junction.

Border Gateway Protocol (BGP)

Border Gateway Protocol (BGP) are the core routing protocol of the internet and responsible to maintain a table of Internet protocol networks which authorize network reaching capability between AS. The Border Gateway Protocol (BGP) expressed as path vector protocol. It doesn’t employ conventional IGP metrics but making routing judgment based on path, network policies. It is created to replace the Exterior Gateway Protocol (EGP) routing protocol to permit completely decentralized routing in order to permit the removal of the NSF Net which consent to internet to turn into a truly decentralized system. The fourth version of Border Gateway Protocol (BGP)has been in use since 1994 and 4th version from 2006 .The 4 version RFC 4271 has many features such as it correct a lots of previous errors, illuminating vagueness and brought t the RFC much nearer to industry practice.

Intermediate System-to-Intermediate System (IS-IS)

Intermediate System-to-Intermediate System (IS-IS)is a great protocol used by network devices to determine the best way to promoted datagram from side to side a packet switched network and this process is called routing. It was defined in ISO/IEC 10589 2002 within the OSI reference design. Intermediate system-to-intermediate system (IS-IS) differentiate among levels such as level 1and level 2. The routing protocol can be changed without contacting the intra area routing protocol.

Q.4. Discuss the evolution of 2.5G TDMA standard.

2.5G,which stands for "second and a half generation," is a cellular wireless technology

developed in between its predecessor, 2G, and its successor, 3G.

The term "2.5G" usually describes a 2G cellular system combined with General Packet Radio

Services (GPRS), or other services not generally found in 2G or 1G networks.

Three different upgrade paths have been developed for GSM carriers.

(a) High Speed Circuit Switched Data (HSCSD);

(b) General Packet Radio Service (GPRS);

These options provide significant improvements in Internet access speed

HSCSD for 2.5G GSM

High Speed Circuit Switched Data is a circuit switched technique that allows a single mobile subscriber to use consecutive user time slots in the GSM standard. That is, instead of limiting each user to only one specific time slot in the GSM TDMA standard, HSCSD allows individual data users to use consecutive time slots in order to obtain higher speed data access on the GSM network. HSCSD increases the available application data rate to 14,400 bps, as compared to the original 9,600 bps in the GSM. HSCSD is good for dedicated streaming Internet access or real-time interactive web sessions and simply requires the service provider to implement a software change at existing GSM base stations.

GPRS for 2.5G GSM and IS-136

General Packet Radio Service is a packet-based data network, which is well suited for non-real time Internet usage, including the retrieval of email, faxes, and asymmetric web browsing, where the user downloads much more data than it uploads on the Internet. HSCSD dedicates circuit switched channels to specific users, But GPRS supports multi-user network sharing of individual radio channels and time slots. Thus, GPRS can support many more users than HSCSD.

When all eight time slots of a GSM radio channel are dedicated to GPRS, an individual user is able to achieve as much as 171.2 kbps (eight time slots multiplied by 21.4 kbps of raw data throughput). As is the case for any packet network, the data throughput experienced by an individual GPRS user decreases as more users attempt to use the network or as propagation conditions become poor for particular users.

EDGE for 2.5G GSM and IS-136

Enhanced Data rates for GSM Evolution is a more advanced upgrade to the GSM standard, and requires the addition of new hardware and software at existing base stations.

EDGE uses a new digital modulation format, 8-PSK (octal phase shift keying). Because of the higher data rates and relaxed error control covering in many of the selectable air interface formats, the coverage range is smaller in EDGE than in HSDRC or GPRS.

EDGE uses the higher order 8-PSK modulation and a family of MCSs for each GSM radio channel time slot, so that each user connection may adaptively determine the best MCS setting for the particular radio propagation conditions and data access requirements of the user.

When EDGE uses 8-PSK modulation without any error protection, and all eight times slots of a GSM radio channel are dedicated to a single user, a raw peak throughput data rate of 547.2 kbps can be provided.

Q.5. Difference between 1G, 2G, 3G & 4G.

Parameters	1G	2G	3G	4G
Image
Name	1st Generation Mobile Network	2nd Generation Mobile Network	3rd Generation Mobile Network	4th Generation Mobile Network
Introduced in year	1980s	1993	2001	2009
Location of first commercialization	USA	Finland	Japan	South Korea
Technology	AMPS (Advanced Mobile Phone System), NMT, TACS	IS-95, GSM	IMT2000, WCDMA	LTE, WiMAX
Multiple Address/Access system	FDMA	TDMA, CDMA	CDMA	CDMA
Switching type	Circuit switching	Circuit switching for Voice and Packet switching for Data	Packet switching except for Air Interface	Packet switching
Speed (data rates)	2.4 Kbps to 14.4 kbps	14.4 Kbps	3.1 Mbps	100 Mbps
Special Characteristic	First wireless communication	Digital version of 1G technology	Digital broadband, speed increments	Very high speeds, All IP
Features	Voice only	Multiple users on single channel	Multimedia features, Video Call	High Speed, real time streaming
Supports	Voice only	Voice and Data	Voice and Data	Voice and Data
Internet service	No Internet	Narrowband	Broadband	Ultra Broadband
Bandwidth	Analog	25 MHz	25 MHz	100 MHz
Operating frequencies	800 MHz	GSM: 900MHZ, 1800MHz CDMA: 800MHz	2100 MHz	850 MHz, 1800 MHz
Band (Frequency) type	Narrow band	Narrow band	Wide band	Ultra Wide Band
Carrier frequency	30 KHZ	200 KHz	5 MHz	15 MHz
Advantage	Simpler (less complex) network elements	Multimedia features (SMS, MMS), Internet access and SIM introduced	High security, international roaming	Speed, High speed handoffs, MIMO technology, Global mobility
Disadvantages	Limited capacity, not secure, poor battery life, large phone size, background interference	Low network range, slow data rates	High power consumption, Low network coverage, High cost of spectrum licence	Hard to implement, complicated hardware required
Applications	Voice Calls	Voice calls, Short messages, browsing (partial)	Video conferencing, mobile TV, GPS	High speed applications, mobile TV, Wearable devices

About Admin of the Blog:

Rajnish kumar is the CEO/founder of Tech Hindi Sagar .He is a Computer Science Engineer ,Web Designer,Web Developer and a Pro Blogger..Inspired to make things looks better.