Q31) How much minimum data rate is required for real time application ?
Answer: For any realtime application minimum data 30kbps required.
Q32) What is Realtime application ?
Answer: Realtime applications includes voice, video conferencing & Online gaming. In between realtime application and non-realtime application, preference is given to Realtime application for spectrum distribution.
Q33) What is non-realtime application ?
Answer: Non-Realtime applications includes multimedia file transfer & online chatting.
Q34) What are types of topology?
Answer: Types of Topology
There are five types of topology in computer networks:
1. Mesh Topology
2. Star Topology
3. Bus Topology
4. Ring Topology
5. Hybrid Topology
Q35) What are the layers of TCP/IP and OSI model.
Answer:
8 Layers of OSI model:
4 Layers of TCP/IP Model:
Q36) On which frequencies does Wi-Fi work ?
Answer: Wi-Fi works on two frequencies 2.4GHz and 5GHz
Q37) What are the IEEE standards of WLAN ?
Answer: IEEE 802.11A operate at 5GHz frequency band.
Q38) What is difference between 802.11a and 802.11b ?
Answer: 802.11a is based on Orthogonal Frequency Division Multiplexing(OFDM) whareas 802.11b is based on Direct Sequence Spread Spectrum(DSSS).
Q39) What are the advantages of WLAN Routers?
Answer: Advantages of WLAN Routers
- WLAN Routers share IP address in the home and small office networks.
- WLAN Routers are ideal for wireless networks in public areas, especiall if there are multiple networks that are accessible.
- WLAN Routers improve the network management.
- Routers only send packets to specific, directed addresses. They do not forward the often numerous broadcast packets that are sent out by other devices.
- This result in an increase in the network performance.
Q40) State design requirements for WLAN.
Answer: The following are among the most important requirements for wireless LANs:
- Throughput: The medium access-control (MAC) protocol should make as efficient use as possible of the wireless medium to maximize capacity.
- Number of nodes: Wireless LANs may need to support hundreds of nodes across multiple cells.
- Connection to backbone LA: In most cases, interconnection with stations on a wired backbone LAN is required. For infrastructure wireless LANs, this is easily accomplished through the use of control modules that connect to both types of LANs. There may also need to be accommodation for mobile users and ad hoc wireless networks
- Service are: A typical coverage area for a wireless LAN has a diameter of 100 to 300 m
- License-free operation: Users would prefer to buy and operate wireless LAN products without having to secure a license for the frequency band used by the LAN.
- Dynamic configuration: The MAC addressing and network management aspects of the LAN should permit dynamic and automated addition, deletion, and relocation of end systems without disruption to other users.
- Battery power consumption
- Transmission robustness and security
- Collocated network operation
Q41) What are advantages of WLAN ?
Answer: Advantages of wireless local area network (WLAN) :
- It's a reliable sort of communication.
- As WLAN reduces physical wires so it's a versatile way of communication.
- It’s easier to feature or remove workstation.
- It’s economical and provides High data rate as coverage area is small.
- This result in an increase in the network performance.
- Light of sight is not required for propagation.
- Disadvantages of wireless local area network (WLAN) :
- It has limited coverage area.
- Communication is not very secure and unauthorised access is common.
- Licence is required.
Q42) What is the difference between WLAN and WPAN ?
Answer:
| Parameter | WLAN | WPAN |
|---|---|---|
| Standard | IEEE 802.11.x = a, b, e, f, g |
IEEE 802.15.1, 802.15.3, 802.15.4 |
| Definition | A wireless local area network(WLAN) is a wireless computer network that links two or more devices using a wireless distribution method within a limited area such as a home, school, computer laboratory or office building. |
A wireless personal area network(WPAN) is a low range wireless network which covers an area of only a few dozens of meters |
| Frequency Band | 2.4GHz and 5GHz ISM | 2.4GHz and also 868/900MHz ISM |
| Range | 30m for indoor and 300m for outdoor |
10m to 100m |
| Modulation | OFDM and DSSS | DSSS, O-QPSK, G-FSK |
| Application | Mobile extension of wired networks |
Cable replacement for peripherals |
Q43) What Infrared Frequency band and wavelength ?
Answer: Infrared Frequency has frequency range of 300GHz to 430THz and wavelength ranges in between 1mm to 700nm.
Q44) What is the difference between licensed and unlicensed spectrum ?
Answer: The big difference between licensed and unlicensed bands is that the licensed bands are allowed to be used only by the company that licensed them, whereas the unlicensed bands are used by anyone who wants to use them."
Q45) Which frequency band is used as unlicenced frequency band ?
Answer: Mainly frequency range from 2.4GHz to 2.4835 GHz is used as unlicensed frequency. The three frequency bands used as unlicensed spectrum are the 900 MHz, 2.4 GHz and 5.8 GHz.
Q46) What does WiMax stands for and its type ?
Answer: WiMax stands for Worldwide Interoperability for Microwave Access.WiMax is mostly used for metropolitan area network.
Q47) State advantages of IEEE 802.16 .
Answer:
- 1] Last Mile connectivity:
- Replacement for cable net/DSL.
- DSL max reach is 3 miles
- 2] Roaming between networks
- Between one WiMax tower to another between 802 Network.
- 3] Flexibility
- 4] Scalability: Flexible channel bandwidth.
Q48) What are advantages of WiMax/MAN/WiBro ?
Answer:Following are advantages of WiMAX:
- It supports very high speed voice and data transfer over longer distances.
- Single wimax BS serves hundreds of users.
- It is considered to be cheaper alternative to broadband wired technologies viz. ADSL, Cable modem etc.
- Higher speed can be achieved.
- Higher coverage range and cellular like performance are achieved with mobile wimax.
- Disadvantages of WiMAX :
- LOS (Line of Sight) connection is needed for subscribers located at the far distant from the WiMAX BS.
- Bad weather conditions such as rain will interrupt the wimax signal and often cause loss of connection.
- Wimax is power consuming technology and requires significant electrical support.
Q49) Differentiate between WiFi and WiMax.
Answer: .
Difference between WiFi and WiMax:
| WiFi | WiMax |
|---|---|
| Wifi is defined under IEEE 802.11x standards where x stands for various WiFi versions. | WiMax is defined under IEEE 802.16y standards where y stands for various WiMax versions. |
| WiFi is for LAN (Local Area Network) applications. | WiMax is for MAN (Metropolitan Area Network) applications. |
| WiFi does not guarantee any Quality of Service (Qos). | WiMax guarantee Quality of Service (Qos). |
| WiFi network range is around 100 meters. | WiMax network can reach about 50-90 km. |
| WiFi MAC layer uses CSMA/CA protocol which is not connection oriented. | WiMax is connection oriented in nature. |
| WiFi is short range technology. | WiMax is long range technology. |
| WiFi connection can transmit upto 54 mbps. | WiMax connection can transmit upto 70 mbps. |
Q50) Explain HIPERLAN.
Answer: HIPERLAN is the short form of High Performance Radio LAN. It is variant of IEEE 802.11 standard.
- Following are the features of HIPERLAN/1:
- Operates at 5GHz
- Supports data rate upto 19 Mbps.
- It uses SC (Single Carrier) modulation such as GMSK.
- It uses complex equalizer to take care of delay spread.
- Following are the features of HIPERLAN/2:
- Operates at 5GHz with 455MHz bandwidth.
- Supports data rate of 6 Mbps to 54 Mbps similar to 802.11a
- it uses multi carrier (i.e. OFDM) modulation like 802.11a
- It uses two bands one for indoor use and the other for outdoor use with power at 200 milliWatt and 1 Watt respectively.
Q51) Differentiate Ad-hoc and Cellular Networks.
Answer:
Let’s see that the difference between Cellular Network and Ad hoc Network :
| S.NO | Cellular Network | Ad hoc Network |
|---|---|---|
| 1. | The network routing of cellular network are centralized, all the traffic goes through the base station. | The network routing of adhoc network are distributed, no centralized system such as base station needed. |
| 2. | Circuit Switching are used. | Packet Switching are used. |
| 3. | It has single hop type. | It has multiple hopes |
| 4. | Star topology are used. | Mesh topology are used. |
| 5. | It takes Higher cost and takes more time for deployment. | It takes lower cost and does not take more time for deployment. |
| 6. | It is used in Designed and developed for voice traffic. | It is used in Designed to meet best effort data traffic requirements. |
| 7. | Here Low call drops during mobility due to seamless connectivity across region. | Here higher breaks in the path during mobility. |
| 8. | It requires periodic maintenance so it is costly. | Here nodes are self-organizing and hence it is less costly. |
| 9. | The allocation bandwidth is guaranteed and easy. | The allocation of bandwidth is based on shared channel using complex MAC algorithms. |
| 10. | IS-95, IS-136, GSM, Mobile WiMAX, CDMA, LTE technologies are used. | WLAN 802.11e technology are used. |
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