Interview Questions.

Question 1. What Is Bluetooth?

Answer :

Bluetooth is a wi-fi technology standard used to alternate information over brief distances.
The statistics is exchanged from fixed and mobile gadgets with the aid of creating Personal Area Network with safety at high degree. 
Bluetooth became at the start conceived as a wi-fi change to RS-232 cables. 
It resolves the problems synchronization by connecting numerous devices. 
It calls for a low-cost transceiver chip that needs to be included in all the devices.
The connections can be factor to factor or multipoint.
A built in verification and encryption is likewise furnished.
Question 2. Bluetooth Is Called A Cable Replacement Technology. Explain.

Answer :

Bluetooth allows Personal Area Networks with out the cables.
It gives connectivity to many mobiles users at a time for sharing without wires. 
Bluetooth chip is designed for changing cables by means of transmitting the records at a unique frequency from sender to receiver. 
Bluetooth is an cheaper,low-strength, brief range radio primarily based era.
Cabling entails quite a few value foe execution.
Bluetooth is tons greater flexible and robust than cabling.
They even require a very low bandwidth of facts switch.
Networking Interview Questions
Question three. Explain About Tcp Flow Control?

Answer :

TCP makes use of a glide manage protocol from one end to another cease for avoiding the sender to send statistics too quickly for the TCP receiver to receive and technique it in a reliable way. Machines of diverse community can communicate fast via having the waft manipulate mechanism.

TCP makes use of a sliding window waft control protocol. In each TCP phase, the receiver is specified in a acquire window subject, the additional received records that is to buffer for the connection. When a window of size zero is marketed via a receiver, the information sending is stopped through the sender and starts offevolved the persist timer. The TCP lifeless lock state of affairs is blanketed by using the persist timer. The TCP sender sends the packet and the receiver sends the acknowledgement with the new length of window, at the time of expiring the persist timer.

Question 4. Explain The Working Of Trace Route?

Answer :

Trace direction works by increasing the time-to-stay cost of each successive packets sent in batch. Every 3 packets that have been despatched first, have a time-to-stay cost 1. The next 3 packets have a TTL fee of two and so forth. The host decrements the TTL fee via one and the packet is forwarded to the subsequent host, whilst a packet passes through a host.

When a packet (with a time-to-live fee of 1) reaches a bunch, the packets may be discarded with the aid of the host, and an ICMP time surpassed packet is sent to the sender. A list of hosts, whose packets have traversed enrouted to the vacation spot, is utilized by the trace route application.

Networking Tutorial
Question 5. What Is Piconet?

Answer :

Piconet is an advert-hoc network by using linking a set of users which makes use of blue teeth technology protocols for allowing one ‘master’ tool to interconnect with as much as seven active ‘slave’ devices. Further, up to 255 slave devices could be inactive or packed and the master tool can carry into lively fame at any given point of time.

The variety of Piconet will range based totally at the blue tooth tool elegance. The statistics transfer charge varies round 200 to 2100 KB/S, depending upon the synchronous or asynchronous connection usage, and the quantity of devices connected inside the piconet.

Firewall Support Interview Questions
Question 6. Explain The Following Terms: Icmp, Arp, Multicast, Broadcast

Answer :

Internet Control Message Protocol: This protocol is used for at the same time as checking the connectivity using ping command
Address Resolution Protocol: This protocol is used to recognize approximately the houses of TCP/IP. For instance, to recognise different system MAC addresses.
Multicast: Communication between single sender and a list of choose recipients in a network.
Broadcast: To send messages to all the recipients simultaneously in a community.
Question 7. List Out The Differences Between Udp And Tcp?

Answer :

TCP is connection oriented protocol, wherein as UDP is connection much less protocol.
In TCP, records is sent after setting up the relationship from consumer to server, in which as statistics is sent in chunks in UDP.
TCP is dependable – until the relationship fails absolutely, the message could be reached to the destination.
UDP is unreliable – there are probabilities to lose the statistics sent on the way.
TCP is an ordered protocol – while messages are despatched one after different, the primary message could be acquired first.
UDP is an unordered protocol – while  messages are sent, the order in their arrival at the vacation spot is unknown.
UMTS Tutorial UMTS Interview Questions
Question 8. What Is Meant By The Term 'ip Spoofing'?

Answer :

IP Spoofing: Sending messages by way of intruder to a laptop gadget with an IP deal with that shows the message is sent from a relied on host, for gaining unauthorized get admission to to computer systems. The hacker / intruder first utilize a selection of strategies for finding an IP cope with of a depended on host. Later he alters the packet headers, if you want to supply an illusion that the packets are despatched from the host.

Question 9. What Is Rj-45?

Answer :

RJ-forty five stands for Registered Jack – 45.
It is an eight-twine connector for connecting laptop structures directly to a LAN, mainly Ethernets.
These connections are comparable in appearance to the ever-present RJ-eleven, which are used in connecting smartphone system, with little greater width. 
It is one of the most normally used connectors.
Two wiring schemes like T568A and T568B are used to terminate the twisted-pair cable to the connector interface.
They appearance similar to the RJ-eleven connectors that are used for connecting the telephone equipments but are wider then them.
Routing Protcol Interview Questions
Question 10. Which Technology Is Used To Avoid Interference In Bluetooth?

Answer :

Blue teeth uses frequency hopping generation. In this technology, seventy nine hop frequencies are transmitted and received from 2402 to 2480 mhz. Hopping in a pseudo random collection at a fee of 1600 instances in a 2d. Guassian frequency shift keying modulation is utilized with a maximum facts switch charge of 721 kbps. Bluetooth protocol stack is developed and TCP/IP imported layers are used on this generation.

Interference is being prevented by using utilizing the frequency-hop(FH) unfold spectrum era. It is adaptable for low-energy, low-fee radio implementations and also used in certain wireless LAN products.

The fundamental gain with this era transmission is the high charge of 1600 hops / ps. Another advantage is, brief packet duration is also utilized by Bluetooth.

Wi-Fi Tutorial
Question 11. What Is Tcp Connection Establishment And Tear Down?

Answer :

The following is the process for TCP connection:

As connection is made by means of synchronizing sender and receiver and the OS is knowledgeable about the connection establishment.
Sender begins sending information and gets recounted. Soon after the sender sends the facts, a timer is began.
When the sender isn't acquired any acknowledgement ever after exceeding the timer’s restrict, the facts is transmitted.
If windowing happens, buffer on the receiver is full, then a prevent signal is sent by means of the sender and prevents sending records.
Soon after processing all statistics, a go signal is despatched through the sender, observed via transmitting records once more.
Wireline Broadband Interview Questions
Question 12. What Is The Signal Strength Transmitted By Cell Phones?

Answer :

The value of the electric subject at a reference factor, which is substantial distance from the transmitting antenna, is referred to as signal power. Signal strength is expressed in voltage/duration or sign energy acquired by the antenna. In cellular telephones, the signal energy is generally expressed in dB-microvolts in keeping with meter or in decibels above a reference degree of 1 milliwatt.

Networking Interview Questions
Question 13. What Method Is Used For Voice Transfer? Brief About The Method Used?

Answer :

For Voice transfer, SCO (Synchronous Connection Oriented) hyperlinks are used for properly synchronization and reliability.

Wireless Security Tutorial
Question 14. Explain The Modulation Techniques Used In Bluetooth Technology?

Answer :

Blue teeth uses Frequency Hopping Spread Spectrum technique which is used in unfold spectrum sign transmission. During radio transmission, frequencies are switched repeatedly, to help decreasing unlawful get entry to to go paths which reasons interruptions. FHSS makes Bluetooth verbal exchange greater sturdy and at ease. The pace of interferences from different devices could be decreased, though it'll no longer purpose the transmission to prevent. 
Adaptive modulation and coding strategies, OFDM, GMSK, QAM, CDMA, DMT and similar strategies are utilized in the areas of wi-fi, mobile and satellite conversation systems. These modulations are utilized in wireless, cellular, wired line and satellite tv for pc communication systems.

New technology including MIMO, BLAST and area-time coding are used in transmission statistics verbal exchange structures.

Question 15. What Are The Technical Characteristics Of Bluetooth?

Answer :

The following are the technical characters of a Bluetooth device:

The gadgets are either a one chip solution or a couple of chips in popular. Blue tooth tool has three primary elements – RF, baseband processor and hyperlink manager (can be a CPU core like eight or 16 bit Reduced Instruction Set Computer. A BT module in multiple chips, usually 2 or three chip, like RF on a chip are produced with the aid of certain providers.

For a unmarried chip solution, the following data can be used for referencing from a particular dealer.

Package :  81 ball BGA, 8mm x 8mm
Supply Voltage : 2.7 – three.3v
Power Consumption : Data transmitting @ 4dBm – type 41mA
Voice Only Connection : 15mA for HV3 packets, 30mA for HV1
RI Page Scanning : 420uA
Inquiry Scanning + RI Page Scanning : 560uA
Park mode (1 2nd interval)  : 120uA
Standby state  : 10uA
The components, the chip, memory and the crystal, antenna can be located on a PCB about 20mm x 15mm. The thickness of the chip is about 1.25mm or 1.Fifty five mm..

Network Administrator Interview Questions
Question 16. Explain The Term 'airport' In Bluetooth?

Answer :

Airport is general (802.11) and has a quicker switch charge. Technologically it's far extra superior, more rugged and smaller and able to getting used everywhere. It is 10mb/sec, 50 meters, 10 lively gadgets. Apparently, Bluetooth is 1mb/sec, 10 meters and seven lively gadgets.

Wireless Communication Tutorial
Question 17. What Does Fec Mean In Bluetooth?

Answer :

FEC stands for Forward Error Correction. On the statistics payload, FEC lowering the range of retransmissions.
Within blue enamel, there are 2 variations specifically, 1/three FEC and 2/3 FEC. 
The 1/three model is three times repetition of each statistics bit. 
The 2/3 version is a shortened Hamming code. 
It is called a technique of acquiring errors manage in records transmission wherein the supply sends redundant records and the destination will recognize it without the errors.
They are used for broadcasting to many locations from a single supply.
Remote Method Invocation Interview Questions
Question 18. How Frequency Hopping Is Used For Security In Bluetooth?

Answer :

Blue enamel technology uses Adaptive Frequency Hopping and capable to reduce interference among wi-fi technologies with the help of two.Four GHz spectrum. In order to take the gain of the to be had frequency, Blue teeth’s AFH works in the spectrum and is performed by way of the technology detecting other devices in the spectrum and fending off the used frequencies. Efficient transmission within the spectrum at high degree of interference immunity is accomplished via adapting hopping among seventy nine frequencies at 1 MHz intervals.

Firewall Support Interview Questions
Question 19. What Is 3g?

Answer :

Definition: 3G, referred to as third Generation, is a widespread for cell / cellular phones. It presents the offerings that fulfill the International Telecommunication Union specs.

The utility services of 3G consist of wireless voice smartphone, cellular internet get entry to, video calls and cell tv – all in a mobile surroundings.

3G permits simultaneous use of speech and facts offerings
3G presents height facts quotes of as a minimum 200 KBits according to the IMT-2000 specification.
Mobile broadband access of numerous MBits to computer laptop structures, clever phones is provided by trendy three.5G, 3.75G versions.
Question 20. What Are 3g Standards?

Answer :

3G standards:

UMTS:

Universal Mobile Telecommunications System – One of the 3G cellular telecommunications technology, also being evolved right into a 4G generation.
Most common shape of UMTS uses W-CDMA as an underlying air interface.
UMTS additionally covers Radio Access Network – UMTS Terrestrial Radio Access Network (UTRAN), and Mobile Application Part (MAP).
Users are authenticated through USIM playing cards (Universal Subscriber Identity Module).
CDMA2000

Also referred to as IMT Multi-Carrier (IMT-MC), makes use of CDMA channel get entry to for sending voice, statistics and signaling statistics among cellular telephones and mobile web sites.
The standards are CDMA2000 IX, CDMA2000 EV-DOR Rev.Zero, CDMA2000 EV-DO Rev.A and CDMA2000 EV-Rev.B. They are approved radio interfaces for the ITU’s IMT-2000.
Wi-Fi Interview Questions
Question 21. What Are The Advantages And Disadvantages Of 3g?

Answer :

Advantages of 3G:

Overcrowding is relieved in current structures with radio spectrum
Bandwidth, protection and reliability are greater
Provides interoperability among provider carriers
Availability of fixed and variable fees
Support to gadgets with backward compatibility with existing networks
Always on line gadgets – 3G uses IP connectivity that's packet based totally
Rich multi media services are available
Disadvantages of 3G:

The cost of cell infrastructure , upgrading base stations could be very high
Needs one-of-a-kind handsets.
Roaming and statistics/voice paintings together has no longer but been carried out
Power consumption is high
Requires nearer base stations and are pricey
Spectrum-license expenses, network deployment fees and handset subsidies subscribers are extraordinary.
Question 22. How Is 3g Different From 2g?

Answer :

Packet facts speed is better in 3G, and it's miles up to 384 KBPS
Voice and sms speed is likewise 384 KBPS in 3G
2G makes use of distinct switching strategies for voice and data, wherein as 3G makes use of unmarried switching, irrespective of facts
3G has at the least 2MB of records hyperlink of a mobile, wherein in 2G the records fee is in KBPS
3G has WiMAX facility for quicker VOIP and internet
2G makes use of GSM TDMA generation with narrowband 200Khz.
3G uses CDMA technology with broadband 5Mhz, with equal frequency provider and time.
Question 23. Explain Gprs ( General Packet Radio Service)?

Answer :

GPRS ( General Packet Radio Service) : 

Packet orientated cellular statistics provider to be had to the users of 2G cellular systems.
It is worldwide machine for communicating thru mobile telephones the usage of GSM in addition to in 3G structures.
GPRS information transfer is charged per MB of visitors transferred, where as in circuit switching, facts transfer is charged consistent with minute of connection time
GPRS is better packet switching provider, instead of circuit switching.
2G mobile structures are blended with GPRS and called 2.5G.
Provides moderate speed facts transfer via the use of unused TDMA channels, including GSM.
Wireless Testing Interview Questions
Question 24. Explain Gsm (worldwide System For Mobile Communications)?

Answer :

GSM (Global System for Mobile Communications):

GSM (Global System for Mobile Communications).
Most famous standard for cellular telephony systems, originated from Groupe Special Mobile.
The ubiquity of GSM enables the global roaming preparations among cell telephone operators.
Both signaling and speech channels are virtual, and for that reason GSM is taken into consideration as 2G cell phone gadget.
GSM fashionable benefited clients the capacity to roam and switch carriers without changing the hand sets and network operators.
GSM implements low-price implementation of Short Message Service.
UMTS Interview Questions
Question 25. Explain Hlr (home Location Register) , Iden(included Digital Enhanced Network), I-appli ?

Answer :

HLR (Home Location Register) :

For GSM and CDMA wi-fi networks
It’s duty is to authenticate and authorize subscribers and their offerings.
IDEN (Integrated Digital Enhanced Network) : 

A wireless era for Motorola
It has the abilties of digi-cell telephone, 2 way radio, alphanumeric pager and data modem / fax modem in a unmarried network
Operational bands are 800 MHz, 900 MHz and 1.Five GHz
iDEN is based totally on TDMA (Time Division Multiple Access) and GSM structure
For voice compression it makes use of Motorola’s Vector Sum Excited Linear Predictors vocoder.
For delivering 64KBPS over a 25 KHz channel, it uses QAM modulation.
IDEN is designed to serve the cellular consumer for having access to facts quickly without sporting several gadgets.
I-appli : 

i-appli is a Java environment primarily based on CLDC.
Handsets of NTT DoCoMos are using i-appli
It is much like MIDP, but each APIs are incompatible.
Question 26. Explain Umts?

Answer :

UMTS stands for Universal Mobile Telecommunications Systems
One of the rising mobile technology for 3G cellular telephones.
The major benefit of UMTS is, certainly, its velocity
Current prices of broadband records switch is 2MBits / second
The velocity of UMTS makes it possible to flow video that helps film downloads and video conferencing.
In a nut shell, UMTS affords nearly all of the centers of a domestic computer machine while on the pass.
UMTS combines the technologies like wireless, satellite tv for pc which presents seamless transitions between Wi-Fi and satellite.
Wireless Security Interview Questions
Question 27. What Is 4g?

Answer :

A short name for Fourth Generation
A stage of broadband cell communications that supersede 3G
4G is predicted to apply radio spectrum in an efficient way, and as a end result, affords cable-modem transmission speeds to the end users.
This characteristic enables amazing streaming video
Simultaneous connections to more than one excessive-pace networks, called pervasive computing, are expected with the aid of 4G.
Thus seamless handoffs are provided at some stage in a geographical location.
Coverage enhancement technology, like femtocell and picocell are predicted to expand for addressing diverse wishes of cell customers in houses, public buildings and many others.
Routing Protcol Interview Questions
Question 28. What Is International Telecommunications Union And What Are Its Functions?

Answer :

ITU is an intergovernmental agency
Telecommunications are evolved by using ITU by means of public and private companies.
ITU is accountable for adopting policies, global treaties and requirements that governs telecommunications
Functions of International Telecommunications Union:

Maintaining and lengthening the global cooperation for the development
Rational utilization of telecommunications, for promoting green use of technical centers
To harmonize the moves of nations.
Question 29. What Is Cdma2000?

Answer :

CDMA2000 is a Multi-provider code-department multiple get right of entry to version of IMT-2000 popular
CDMA2000 is a 3G wi-fi era.
World’s first 3G commercial system changed into launched by using SK Telecom of South Korea the usage of CDMA2000 1X
CDMA 2000 supports cellular statistics communications at speeds from 144KBPS to 3MBPS
The versions of CDMA2000 have been advanced via Qualcomm and Ericsson
There had been 250,300,000 subscribes world for CDMA by using March 2006.
Enhanced Interior Gateway Routing Protocol (EIGRP) Interview Questions
Question 30. What Is Cdma? Explain The Technology.

Answer :

CDMA stands for Code Division Multiple Access
CDMA is a wireless technology used in transmission of signal from places with excessive Security and noise reduction.
The precept of Spread Spectrum is used to work with CDMA.
Spread sign is under the noise level noise and has no impact on the signal.
CDMA does now not frequency specific to each person. Instead, each channel uses the whole available spectrum.
Individual conversations are encoded with a pseudo-random digital sequence.
CDMA continually affords better capacity for voice and facts communications
CDMA is a not unusual platform for 3G technologies
Analog radio transmission technology like Advanced Mobile Phone System were utilized in CDMA on the time of its inception
A particular code is acquired with the aid of all mobile network customers and is permitted continuous network get right of entry to as opposed to intermittent and timed get admission to.
Question 31. Explain Cdma One And Cdma2000?

Answer :

CDMA One : 

CDMA one refers authentic ITU IS-ninety five CDMA wi-fi interface protocol. It is taken into consideration as a 2G cellular wi-fi technology
The version IS-95A protocol employs a 1.25 Mhz service and facts quickens to fourteen.Four Kbps
The version IS-95B assist information hastens to a hundred and fifteen kbps by way of using 800 MHz / 1.9 GHz.
CDMA2000 :

Also known as IMT Multi-Carrier, a circle of relatives of 3G cellular era requirements.
Used for sending voice, facts and signaling among cell web sites and mobile pones
The standards which include CDMA2000 1X, CDMA2000 EV-DO Rev. 0, are accredited radio interfaces for ITU IMT-2000
CDMA 2000 is backward well matched with its previous 2G generation IS-ninety five
Question 32. Explain Edge?

Answer :

EDGE is an acronym for Enhanced Data GSM Environment
An progressed wireless generation over GSM
A 2nd technology mobile phone technology
EDGE is used for wireless statistics transfer thru cell cellphone connection
Data transfer prices up to 4 times more than GSM networks
With the arrival of Blackberry and iPhone, quicker records switch is sought
Using more sophisticated coding, generally with out excessive end hardware, wireless provider’s base stations are supported for records transfer accelerates to 384 KBPS
EDGE is an opportunity to replacing wireless generation, which include GPRS
EDGE will eventually get replaced by using 3G generation consisting of WCDMA.
Cisco Network Engineer Interview Questions
Question 33. Explain Dect?

Answer :

DECT is one of the wi-fi technology, originated in Europe
DECT became designed to interwork with various networks inclusive of PSTN, ISDN, GSM etc.
The initial wellknown. Of DECT centered on developing air interface that is a radio link among cordless smartphone and the bottom stations
This general plugged into the cellphone socket and the standard protocols for handover between several base stations
All these are connected to the equal workplace switchboard, normally a PABX
The first made from its kind became from Olivetti, turned into a wireless LAN kind product, referred to as NET3.
Wireline Broadband Interview Questions
Question 34. Explain High Speed Packet Access?

Answer :

HSPA is a aggregate of 2 mobile telephony protocols – High Speed Downlink Packet Access and High Speed Uplink Packet Access
HSPA improves the overall performance of current WCDMA protocols.
HSPA offer increased performance with the aid of utilizing schemes of modulation and refining the protocols, thru which the base stations and handsets speak
HSPA is used for better usage of the to be had bandwidth furnished with the aid of WCDMA
HSPA helps data costs of up to fourteen MBit / s within the downlink
HSPA supports information costs of up to 5.Eight MBit / s within the uplink
HSPA reduces the latency and increases as much as 5 instances more gadget potential throughout downlink and twice extra device capability at some stage in uplink
HSPA uses 16QAM for yielding better bit costs
HSPA rollouts are completed through enforcing software upgrades to present 3G networks. This offers HSPA a head begin over WiMax.
Question 35. Explain Ev-do/ Evdo?

Answer :

EVDO stands for Evolution Data Optimized
EVDO is a 3G broadband technology utilized by Verizon, Spring, Alltel
It presents usual download speeds of 600 to 1400 KBPS
A private broadband carrier for wide range of customers
It is continually On
EVDO utilizes CDMA alerts
Users may be linked remotely for the usage of e-mail, downloading big files, spreadsheets etc.
EVDO is quite low price with high capacity
Allows rich web browsing and alertness usage
Seamless roaming, internal net connectivity with out counting on other’s connection, accessibility to the corporate Virtual Private Network by using clients are some of the benefits over WiFi.
Question 36. What Is The Difference Between Cdma And Gsm?

Answer :

The critical variations are:

Data Transfer Speed:

CDMA is quicker than GSM.
CDMA2000 downstream rate is 2 megabits / 2nd, thru EVDO, where GSM downstream rate is up to 384 kilobits / second, thru EDGE technology
Subscriber Identity Module (SIM) cards:

SIM is tied to the network, in place of the real telephone. Phones with card-enabled can be used with any service of GSM
Proprietary handsets are connected to at least one carrier most effective and not card-enabled in CDMA
Roaming:

 GSM vendors have wider insurance of extra rural regions, wherein as CDMA may not cowl rural areas in comparison to GSM providers
International Roaming:

GSM has facility to provide extra global roaming, as the wide variety of connections in world marketplace dominate GSM community.
CDMA telephones do no longer have the capability; but, there are more nations that use CDMA networks.
Network Administrator Interview Questions
Question 37. What Is The Importance Of Cdma In Today’s Cellular World?

Answer :

The transition to digital radio through the system of defining requirements is implementing about 90% inside the cell enterprise.
Smooth transition to virtual requirements is concerned in CDMA technology.
Most often, it can be viewed as stepped forward and alternative generation of TDMA
Moving closer to 4G technology is well matched with CDMA era.
Question 38. What Is The Differentiate Between Cdma And Fdma ?

Answer :

CDMA and FDMA 

CDMA : 

Same frequency is utilized by every consumer and simultaneous transmission takes place
Every narrowband signal is improved via wideband spreading sign, normally called codeword
Every person has a separate pseudo-codeword, i.E., orthogonal to others
Only the favored codeword is detected with the aid of the receivers and others seem as noise
It is obligatory for the receivers to recognize approximately the transmitter’s codeword
FDMA :

When the channel isn't in use, it sits without a doubt idle.
Bandwidth of Channel is particularly narrow (30 KHz), known as narrowband device.
Little or no equalization is needed for spreading symbol time.
Analog links are appropriate for FDMA.
Framing or synchronization bits aren't wished for continuous transmission.
Tight filtering is wanted to minimize interference.
Question 39. What Are The Difference Between Tdma?

Answer :

CDMA and TDMA : 

CDMA 

Power restrained machine
While people speakme, random noise band playing happens
Conversation need to be extracted from the history din
GP is high whilst people speak different languages, that's less complicated to distinguish character speakers
It is hard for distinguishing people, when GP is low.
The system performance may be degraded for every user whilst the variety of users will increase.
Fading would be decreased with huge frequency spectrum
Need to have separate multipath signals with distinct delays by “chip” unit.
TDMA : 

Receiving or transmission is permitted for only one user in a given slot
All slots are assigned cyclically
The transmission is non-non-stop
It is crucial to use digital statistics and modulation
Data rate overhead is between 20% – 30%
Overhead tradeoffs are size of facts payload and latency
Multiple users are shared with unmarried carrier frequency
Handoff is made less complicated through using non-non-stop transmission
All slots are assigned on call for
Due to decreased inter consumer interference, the power control is less stringent.
Question forty. What Is The Difference Between Cdma And Gprs? Which Of Them Is Better? Why?

Answer :

The Differences:

CDMA is one of the styles of cell connections for making calls where as GPRS is a technology for net connections through a cellular phone.
GPRS enables to surf the internet from a cellular cellphone. GPRS era is utilized in different gadgets aside from cellular phones.
W-CDMA generation is faster than GPRS, because the user cares about the technology this is applied for air interface.
Average latency on GPRS is round 1.Three seconds, where as on CDMA is round four hundred milli 2d
GPRS supports best User Datagram Protocol, where as CDMA helps each UDP and TCP
GPRS relies on Network Address Translation and a private IP cope with is assigned to it. On the opposite hand CDMA assigns a public IP cope with CDMA is better due to the fact:
E-mail is pretty mild, until you enter MS-Office.
Pocket PC’s assist for office documents with comparable capability which may be had on Palm OS and Symbian
Upon availability of APIs, a software program developer may want to write various applications, like voice switch, facts transfer to consumer’s account, integrating billing quantity etc.
Web services may be applied.
Remote Method Invocation Interview Questions
Question forty one. Explain Following Forward Link Channels In Cdma System: A.) Pilot Channel B.) Sync. Channel

Answer :

Pilot Channel : 

A ahead hyperlink channel that's a base to mobile that modulates best by means of the pilot PN. It spreads commonplace codes to all indicators transmitted from a given base station.
Several crucial crucial features are provided by way of the pilot channel for forward hyperlinks in IS-95 systems
The pilot channel modulation enables the procedure of time synchronized replica technology on the receiver of the PN spreading sequences. These are utilized on the transmitter for modulating the synchronization, paging and traffic channels. These are transmitted from the equal base station.
Sync-Channel :

A base station transmits a Sync-Channel that spreads with Walsh code 32.
The body of synch channel is 80/3ms long with frame boundary is aligned to the pilot.
Sync channel transmits a unmarried message constantly, referred to as Sync Channel Message.
The Sync Channel Message consists of network data, such as the PN offset that is utilized by the Base Station sector.
The length and content of the message is dependent on the P_REV.
The message transmission charge is 32 bits / body.
The message is encoded to 128 symbols
The message yielding fee is 1200 bits / s.
Question forty two. Explain The Following Two Types Of Hand Off In Cdma System: A.) Soft Handoff B.) Softer Handoff

Answer :

Soft handoff : 

Soft handoff is a characteristic in which a cellular telephone is simultaneously connected to two or greater mobile phones during a single call
It is he overlapping of repeater insurance ones, which permits each mobile telephone set is always nicely in the variety of a specific repeater.
More than one repeater can ship and acquire alerts to transmit alerts to and from mobiles.
All repeaters are used with the identical frequency channel for each cellular phone set.
Practically no useless zones and as end result, the connections seldom interrupted or dropped. 
Softer handoff : 

Softer handover is a massive gentle handover wherein the brought and eliminated hyperlinks belong to the same node.
Macro diversity with most ratio combining might be executed inside the identical node.
The movement of handoff, while a person may be served in some other cell greater efficiently (less power emission, much less interference), is the most obvious motive for better performance.
Wi-Fi Interview Questions
Question forty three. What Is Gsm?

Answer :

Short form of Global System for Mobile Communications, is a wireless network machine
A general for virtual cellular cell communications
International roaming preparations are enabled among mobile community operators, by way of supplying the subscribers to use their private cellular phones everywhere in the world.
GSM is considered as second generation mobile, as signaling and speech channels are virtual
The companies may be replaced without changing cellular phones.
The ubiquity of GSM implementations is also allowing the switching between community operators, who can choose gadget from many GSM gadget vendors.
GSM pioneered low price SMS implementation.
The GSM fashionable consists of a global emergency telephone wide variety function.
Question 44. Explain The Services Offered By Gsm.

Answer :

The offerings presented by using GSM are ISDN well matched
GSM allows synchronous statistics and asynchronous facts to be transported as bearer service, one of the telecommunication services supplied by using GSM, and paperwork ISDN terminal
The records can be both obvious provider or nontransparent carrier
Telephony is one of the services supplied by using GSM, which an emergency and the provider company is notified by means of dialing three digits
By using suitable fax adaptor, G3 fax carrier is supported
One of the functions of GSM is Short Messaging Service
Certain offerings, particularly supplementary offerings are supplied on top of teleservices or bearer services by way of GSM, consisting of, caller identification, name forwarding, multiparty conversations, barring outgoing calls and phone ready.
Question forty five. What Is The Maximum Data Rate Supported By A Gsm System?

Answer :

The maximum statistics charge supported with the aid of a GSM device is nine.6 kbps.
However there are extensions to GSM trendy to improve throughput.
GPRS is one of the prolonged GSM carrier.
The extended standards of GSM lets in theoretical facts fees on the order of 114 Kbit/s, however with throughput toward 40Kbit/s in exercise.
Question 46. Explain The Following Techniques In Gsm: A.) Sectorization Of A Cell B.) Frequency Re-use C.) Transmitted Power Control D.) Discontinuous Transmission

Answer :

 Sectorization of a cell : 

Sectorization is a process to reduce down device expenses in a cellular community. It influences in traffic load and mobile length
Sectorization reduces co-channel interference, when applied to clusters of cells
The maximum visitors capability of sectored antennas is extra than omnidirectional antennas.
Frequency Re-use :

Frequency re-use is the important thing issue of cell network capability for growing both coverage and ability.
Different frequencies are used by adjoining cells; however hassle does now not rise up to decide the mobile sufficiently a long way aside the use of the same frequency.
Reuse distance and the reuse component are the two factors that influence frequency reusability
The frequency is 1/K, in which K is the variety of cells that can't use the same frequencies for transmission.
Transmitted Power Control :

Transmitted strength manipulate is one of the technical mechanism used within some networking devices
TPC is used for stopping an excessive amount of unwanted interference amongst wi-fi networks
The important concept is to mechanically lessen the transmission output strength used, while different networks are within the equal range.
TPC reduces interference problems and increases the battery ability
The power tiers of a single cellular device can be reduced by way of 6dB
Discontinuous Transmission : 

Discontinuous Transmission, also referred to as DTX in quick is a method of momentarily powering down a cell set whilst there is no voice input to the set.
The average efficiency of a wi-fi voice communication system is optimized through DTX.
Each speaker in a  manner conversation speaks slightly less than half of the time.
The workload of the components in the transmitter amplifiers are made smooth and reduces interference. 
Question forty seven. Which Uplink/ Downlink Spectrum Is Allocated To Following? A.) Gsm – 900 B.) Dcs – 1800

Answer :

GSM – 900: Uplink spectrum is 890.2–914.Eight and downlink spectrum is 935.2–959.8

DCS – 1800: Uplink spectrum is 1710.2–1784.Eight, and downlink spectrum is 1805.2–1879.8

Question forty eight. Explain Equalisation?

Answer :

 Equalisation: 

An adaptive equalizer is employed by a GSM receiver for overcoming the impact of non-ideal channel traits which might be caused by multipath propagation.
Adaptive equalizer is needed due to the fact the channel characteristics are often converting rapid.
Tuning the for each time slot is finished by the equalizer.
Question 49. Explain Interleaving?

Answer :

Interleaving: 

Time variety in a signal conversation machine is acquired through using Interleaving.
The possibility of losing entire bursts might be reduced by means of interleaving.
Total 456 bits from convolution encoder, which includes 20ms of speech, is subdivided into eight blocks. Each block includes fifty seven bits.
All these blocks are transmitted in consecutive time slots.
Enough facts is to be had in 7 blocks, in case one of the blocks is misplaced due to burst errors. This enables complete segment healing by means of using blunders correction.
Question 50. Explain Speech Coding?

Answer :

Speech coding:

Speech coding is all approximately turning voice into digital shape.
Speech is inherently analog, as GSM is a digital system.
The digitization is hired with the aid of ISDN, and the modern cellphone structures that are used for multiplexing voice lines, with excessive speed trunks, optical fiber traces is finished with the aid of Pulse Code Modulation(PCM).
The PCM output is sixty four kbps, that's too excessive over a radio link in feasibility.
The 64kbps signal is redundant.
The set of rules used in conventional cellular is Vector Sum Excited Linear Predictive speech compression.
Question 51. Explain Channel Coding?

Answer :

Channel coding :

The statistics rate for the radio channel is 270 kbps.
The records price is break up into 8 complete fee or sixteen half of price traffic channels, along side signaling channels
In order to have the most chance for detecting and correcting mistakes, the code is complicated in an average propagation course
Forward Error Correction is applied for you to get the speech coder encryption, coding and interleaving in an advanced way
The facts is sent as bursts in 577 mus time slots. Each carries 116 encrypted bits
Every TDMA frame consists of eight or 16 time slots
Transmit time slots are staggered, in order that at some immediate the mobile station will not receive the identical instants while transmitting, which permits the simplifying the filtering requirements
At least one spare slot among transmit and receive is available with this scheme.
Question 52. What Is Frequency Re-use?

Answer :

Frequency Re-use:

Frequency re-use is one of the techniques for enhancing potential and spectral efficiency.
Commercial wi-fi structures are primarily based on Frequency Reuse, that involves the partitioning of an RF radiation vicinity into cellular segments.
A frequency this is some distance sufficient faraway from the frequency within the bordering phase is utilized by one segment of the mobile.
Similar frequency is used at least two cells other than every different.
This exercise permits diverse cell companies to have numerous customers for a given site license. 
Question 53. Explain Gprs?

Answer :

Short form of General Packet Radio System.
GPRS is the following era of GSM, and the idea of the 3G networks.
A packet orientated facts service to be had to users of GSM and IS-136 kind mobile phones.
It complements the existing offerings like circuit-switched cell cellphone connections and the SMS.
Shortest set-up time is introduced for ISP connections.
An optimized mobile carrier for sending and receiving statistics across a cell cellphone network, with much less fee.
GPRS offers data charges of mobile telephony and mild velocity facts switch, the usage of unused TDMA channels.
GPRS does now not need dial-up modem connection.
Sending and receiving e-mails, browsing net are many of the capabilities of GPRS.
Question 54. What Signals Are Transferred In Gprs?

Answer :

GPRS makes use of 2.5 technology of GSM signals.
The radio interface is the equal that of GSM.
GPRS uses 900 / 1800 Mhz, frequency band and GMSK modulation.
The bit costs are EGPRS, similar to EDGE.
Separate hardware and ports need to be delivered and availed. 
Question 55. How Are Gprs Terminals Classified?

Answer :

The GPRS offerings are categorised into 12 carrier instructions as according to the period of the time slots occupied / frame.
Usually 5 time slots per body are occupied together with transmission time slots and reception time slots.
Increase within the number of occupied time slots genuinely reasons the growth in the entire duration of the occupied time slots, in order that extended quantity of facts transmission and receipt are enabled.
All the 12 provider classes are further categorised into higher and lower lessons as according to the relative period of time slots.
Higher velocity records communique can be transmitted with excessive-elegance GPRS provider via setting high transmission strength and placing the period of the time slots long.
Question fifty six. What Gross Data Rate Does Gprs Provide?

Answer :

GPRS is a packet oriented cell data provider.
The records transfer is charged in step with megabyte of site visitors.
GPRS provide gross statistics rate of 22.80 KBPS / time slot.
Voice makes use of simplest 13KBPS/ time slot and the rest is fed on by means of Error Correction Code.
Error connection code is utilized for detecting and correcting the transmission mistakes.
As voice is compressed, the usage of Error connection code is obligatory.
In the 2G systems it provides a fee from fifty six up to 114 kbits/s.
Question fifty seven. What Is Piggybacking In Context To Wi-fi?

Answer :

Piggybacking is a term which states that something that is driving at the lower back of something else to complete his/her cause, just like just like an idiom setting gun to some other’s shoulder and appearing Hunting, so piggybacking is a term used to consult get right of entry to of a wi-fi net connection by means of bringing one’s very own computer in the variety of every other’s wireless connection, and the usage of that service without the subscriber’s express permission or information. It is a legally and ethically debatable exercise, with laws that modify in jurisdictions around the sector. Piggybacking is an unauthorized tapping into any other’s reference to a public utility.

For e.G.- So piggybacking can take area like after I am gaining access to the wi-fi connection of my neighbour Wi-Fi with out his/her understanding by using hacking his static ip cope with, then it might be feasible for me to get admission to the Wi-Fi connection of others.

Question fifty eight. What Are The Recommended Channels If You Are Setting Up Three Wlans And Want Minimum Interference Over There?

Answer :

There is a want of choosing the channels for putting in WLANs, to talk; all of the additives of a Wi-Fi network ought to use the equal channel. In the Wi-Fi network in infrastructure mode (using an get admission to point), it relies upon on the channel set at the get right of entry to factor.

For better effects when using Wi-Fi, it is essential to modify the channel on the get admission to point in addition to configured on the client, to take the least use channel for your neighbourhood.

 To do that you can use software program inclusive of NetStumbler, with a view to listing the neighbourhood Wi-Fi networks and channels used.

 Note:- The channels maximum regularly used to choose one as unfastened as possible.

 So the endorsed channels are as follows:-

Channel 1: 2.412 MHz
Channel 2: 2.417 MHz
Channel three: 2.422 MHz
Channel four: 2.427 MHz
Channel 5: 2.432 MHz
Channel 6: 2.437 MHz  
You can select from these channels whilst putting in the WLANs.

Question 59. How To Crack Wi-fi Network, If You Are Using Wep (stressed Equivalent Privacy) Password With Backtrack?

Answer :

The first line of defense of your Wi-Fi network is encryption, which encodes the statistics transmitted among your PC and your wi-fi router.
 WEP abbreviates (Wireless Encryption Protocol). It is a less-at ease protocol than WPA (Wireless Protected Access). Since WEP is noticeably clean to crack, so you ought to use the same form on all gadgets for your community. If you've got an older router that helps WEP only you’ll be great safest if you use 128-bit bit WEP keys but additionally test the producer’s Web website online for a firmware update so that it will upload WPA guide.
Two of the most popular applications used for honestly cracking the WEP key are Airsnort and Aircrack. Airsnort may be used with the .Dump documents that Kismet gives; and Aircrack may be use with .Cap files that Airodump affords
Question 60. Differentiate Between Ad-hoc And Infrastructure Topology And Also Explain With Their Advantages And Disadvantages?

Answer :

Wireless networks normally paintings in certainly one of two configurations: Ad-Hoc or Infrastructure.

Ad-Hoc is Latin that means “for this motive” so these are the networks that are basically created for a few cause. So these are the group of workstations which talk without delay witch each different to exchange records. An Ad-Hoc network is likewise known as as a peer to peer network. 
Here are a few advantages of an Ad-Hoc community are:-

The opportunities with Ad-Hoc community are pretty endless.
Ad-Hoc networks are easy to set up.
Ad-Hoc networks are less expensive.
 Ad-Hoc networks are speedy.
Disadvantages of an Ad-Hoc community are as follows:-

It isn't capable of get into the mainstream stressed neighborhood area community.
It desires extra technology to guide their reliability.
As the network increases its speed slows down substantially.
In Infrastructure mode, community includes an access point while the wi-fi clients connect with an get right of entry to point, which in turn bridges to a community. Infrastructure community can bypass records thru a critical facts hub which can be each, hardware or software tool on a laptop. So below this gadgets in a wi-fi community are set up to communicate via an get admission to factor. 
An infrastructure network enables you to:-

a) In this you do not need to manage over the path your statistics takes.
B) Connect to a stressed community.
C) Extend your wi-fi network’s variety.
D) Utilize roaming potential.
Disadvantages for Infrastructure community are:-

1. Use of more wireless get entry to factors.
2. This boom the cost of enforcing a wi-fi network answer.
Question sixty one. How Do You Secure A Wireless Network?

Answer :

Key factors for securing a wireless community are as follows:-

Verify that your PC’s software firewall is became on, and that Window’s report-sharing function is off; it’s off by means of default in Window’s XP with Service Pack 2.
Never send financial institution passwords, credit score card numbers, private e-mail, or other sensitive facts unless you’re sure you’re on comfy website: Look for the lock icon inside the bottom-right nook of your browser, as well as a URL inside the address bar that starts with https. Such websites construct of their own encryption.
Always turn your Wi-Fi radio off when you're now not at a hotspot: Hackers can use it to create peer-to-peer Wi-Fi connections together with your laptop and get right of entry to it without delay.
For better safety, recollect signing up for a paid subscription to a hotspot network along with Boingo or T-Mobile. Both organizations offer connection software program that encrypts your sessions routinely.