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Understanding Electromagnetic Waves in Networks & Wireless Communication, Schemes and Mind Maps of Physics

Punjab Technical UniversityPhysics

The reasons why electromagnetic waves with very low frequency are not used for data transmission in computer networks. It also covers various topics related to wireless communication, including multiple access schemes, channel allocation techniques, and cellular networks. Insights into the technical issues in planning a cellular network and introduces concepts such as cell splitting and sectoring.

Typology: Schemes and Mind Maps

2023/2024

Uploaded on 02/12/2024

prakhar-kesari
prakhar-kesari ๐Ÿ‡ฎ๐Ÿ‡ณ

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IT 72-Mobile Communication 2-MARK Questions and
Answers UNIT-I
1. Why are electromagnetic waves with very low frequency not used for data transmission
in computer networks?
๏ƒ˜Low frequency has longer wavelength
๏ƒ˜Data rates depends upon the bandwidth
2. Differentiate hard and soft
handoff? Hard hand off
๏ƒ˜Existing connection must be broken before a new connection is established
๏ƒ˜There is a short break in transmission which can be noticed by the
user Soft hand off
๏ƒ˜A new connection is established before the old one is released
3.How are guard spaces realized between users in CDMA?
The guard space between a pair of users in CDMA systems is the orthogonality
between their spreading codes. The lower the correlation between any pair of spreading
codes is, the better is the user separation.
4. What are the benefits of reservation schemes?
๏ƒ˜No other station is allowed to transmit during that slot
๏ƒ˜Avoidance of congestion
๏ƒ˜Waiting time is clearly known
5. Define a cell.
In mobile communication, the coverage area is divided into smaller areas which are each
served by itโ€™s own base station. These smaller areas are called cells.
6. What is frequency reuse?
Spatially reusing the available spectrum so that the same spectrum can support multiple
users separated by a distance is called frequency reuse.
7. Mention the various multiple access schemes used in wireless communication.
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IT 72-Mobile Communication 2-MARK Questions and Answers UNIT-I

  1. Why are electromagnetic waves with very low frequency not used for data transmission in computer networks? ๏ƒ˜ Low frequency has longer wavelength ๏ƒ˜ Data rates depends upon the bandwidth
  2. Differentiate hard and soft handoff? Hard hand off ๏ƒ˜ Existing connection must be broken before a new connection is established ๏ƒ˜ There is a short break in transmission which can be noticed by the user Soft hand off ๏ƒ˜ A new connection is established before the old one is released 3.How are guard spaces realized between users in CDMA? The guard space between a pair of users in CDMA systems is the orthogonality between their spreading codes. The lower the correlation between any pair of spreading codes is, the better is the user separation.
  3. What are the benefits of reservation schemes? ๏ƒ˜ No other station is allowed to transmit during that slot ๏ƒ˜ Avoidance of congestion ๏ƒ˜ Waiting time is clearly known
  4. Define a cell. In mobile communication, the coverage area is divided into smaller areas which are each served by itโ€™s own base station. These smaller areas are called cells.
  5. What is frequency reuse? Spatially reusing the available spectrum so that the same spectrum can support multiple users separated by a distance is called frequency reuse.
  6. Mention the various multiple access schemes used in wireless communication.

Frequency Division Multiplexing Access, Time Division Multiplexing Access and Code Division Multiplexing Access

  1. What is co-channel interference? Interference between signals from co channels are termed as co channel interference
  2. What is adjacent channel interference? Interference resulting from signals which are adjacent in frequency to the desired signal is called adjacent channel interference.
  3. Mention the different types of cells. Femto cells, pico cells, micro cells, macro cells and mega cells.
  4. What is a picocell? Small cells inside a building that support local indoor networks such as wireless LANs. Size of these cells are in the range of few tens of meters.
  5. What is cellular topology? Cellular topology refers to infrastructure topology employing frequency reuse concept. 13.What are the various channel allocation techniques used in cellular communication? Fixed Channel Allocation, dynamic channel allocation and hybrid channel allocation. 14.What is a cluster? The N cells which collectively use the complete set of available frequencies is called a cluster. 15.What are the technical issues in planning of a cellular network? ๏ƒ˜ Selection of frequency reuse pattern for different radio transmission techniques ๏ƒ˜ Physical deployment and radio coverage modelling ๏ƒ˜ Plans to account for the growth of the network ๏ƒ˜ Analysis of the relationship between the capacity, cell size and the cost of infrastructure 16.What is cell splitting? This is the process of subdividing a congested cell into smaller cells, each with itโ€™s own base station and a corresponding reduction in antenna height and transmitter power. Cell splitting

๏ƒ˜ Involves complicated frequency planning UNIT-II 1.Is IEEE 802.11 and Wi-Fi same?State the purpose of WiFi Ans: No ,WiFi is wireless internet. The laptop has an internal wireless card so it can be connected to wireless routers.No need to have an Ethernet cable to connect to the web. 2.What are the various types of wireless network topologies? Infrastructure network topology and ad hoc topology. 3.What are the classifications of Wireless technologies and systems? ๏ƒ˜ Cellular mobile radio systems ๏ƒ˜ Cordless telephones ๏ƒ˜ Wide-area wireless data systems ๏ƒ˜ High-speed WLANs ๏ƒ˜ Paging/messaging systems ๏ƒ˜ Satellite-based mobile systems

  1. Define BCA. Borrowing Channel Allocation is a method by which more frequencies are allotted dynamically for high traffic cells. 5.Why 800 MHz frequency is selected for mobiles? ๏ƒ˜ Fixed Station Services - 30 MHz to 100 MHz ๏ƒ˜ Television Broadcasting - 41 MHz to 960 MHz ๏ƒ˜ FM Broadcasting - 100 MHz ๏ƒ˜ Air to Ground system - 118 MHz to 136 MHz ๏ƒ˜ Maritime mobile services - 160 MHz ๏ƒ˜ Military Aircraft use - 225 MHz to 400 MHz ๏ƒ˜ Frequency bands between 30 MHz to 400 MHz is crowded with large number of services and above 10 GHz is not used due to propagation path loss, multipath fading and improper medium due to rain activity. So 800 MHz is chosen for mobile communication.
  1. Mention the function of the base station. ๏ƒ˜ The base station serves as a bridge between all mobile users in the cell and connects the simultaneous mobile calls via telephone lines or microwave links to the mobile switching center(MSC)
  2. What are the functions of MSC? The MSC coordinates the activities of all the base stations and connects the entire cellular system to the PSTN.
  3. Define foot print. The actual radio coverage of a cell is known as the foot print. It is determined from field measurements or propagation prediction models.
  4. Mention the basic propagation mechanisms, which impact propagation in mobile communication. The basic propagation mechanisms are, ๏ƒ˜ Reflection ๏ƒ˜ Diffraction ๏ƒ˜ Scattering 10.What is reflection? Reflection occurs when a propagating electromagnetic wave impinges upon an object, which has very large dimension when compared to the wavelength of propagating wave.
  5. What is diffraction? Diffraction occurs when the radio path between the transmitter and eceiver is obstructed by a surface that has sharp irregularities.
  6. What is scattering? Scattering occurs when the medium through which the wave travels consists of objects with dimensions that are small compared to the wavelength and where the number of obstacles per unit volume is large.
  7. What are the principles of Cellular Architecture? o Low power Transmitters and Coverage Zones.
  1. What are Advantages of wireless LAN? ๏ƒ˜ Flexibility ๏ƒ˜ Planning ๏ƒ˜ Design ๏ƒ˜ Robustness ๏ƒ˜ Quality Service ๏ƒ˜ Cost ๏ƒ˜ Proprietary Solution ๏ƒ˜ Restriction ๏ƒ˜ Safety and Security
  2. What are Design Goals of Wireless LAN? ๏ƒ˜ Global Operation ๏ƒ˜ Low Power ๏ƒ˜ License-free Operation ๏ƒ˜ Robust transmission technology ๏ƒ˜ Simplified spontaneous co-operation ๏ƒ˜ Easy to use ๏ƒ˜ protection of investment ๏ƒ˜ Safety and Security ๏ƒ˜ Transparency for application. UNIT-III 1.What is mobility management? Mobility management refers to the operations required for tracking the mobile and restructuring existing connections as it moves. Mobility management consists of Location management and Handoff management 2.Define location management and handoff management.

๏ƒ˜ Location management refers to the activities a wireless network should perform in order to keep track of where the mobile is. ๏ƒ˜ Handoff management handles the messages required to make the changes in the fixed network to handle the change in location during a ongoing communication. 3.What is meant by GPRS? General packet radio services, a technology for radio transmission of small packets of data, esp. between cellular phones and the Internet 4.What do you meant by roaming?. Extending of connectivity service in a location that is different from the home location where the service was registered. Roaming ensures that the wireless device is kept connected to the network, without losing the connection.

  1. What are types of Handover? Intra-cell handover Inter-cell , intra- BSC handover Inter-BSC, intra-MSC handover Inter MSC handover 6.What are subsystems in GSM system? ๏ƒ˜ Radio subsystem(RSS) ๏ƒ˜ Network & Switching subsystem(NSS) ๏ƒ˜ Operation subsystem(OSS) 7.What are the information in SIM? ๏ƒ˜ card type, serial no, list of subscribed services ๏ƒ˜ Personal Identity Number(PIN) ๏ƒ˜ Pin Unlocking Key(PUK) ๏ƒ˜ An Authentication Key(KI)
  2. What is GSM? GSM stands for Global System for mobile Communication. This is the most successful digital mobile telecommunication system.this is second generation and it permits integration of voice and data services. 9.What are the basic elements of telecommunication systems? ๏ƒ˜ Transmitter โ€“ it takes the information and converts into signal ๏ƒ˜ Transmission medium โ€“ it carries the signal ๏ƒ˜ Receiver โ€“ receives the signal and converts it back into usable information.
  1. What is Active scanning? Active scanning comprises sending a probe on each channel and waiting for response. Beacon and Probe response contain the information necessary to join the new BSS.
  2. What is Passive Scanning? Passive Scanning Simply means listening into the medium to find other networks, i.e. receiving the beacon of another network issued by the synchronization function within an access point
  3. What do you mean by Polling? Polling is a strictly centralized scheme with one master and several slave stations. The master can collect the list of stations during the contention phase and can poll these slaves according to many schemes like round robin, random access, reservation scheme etc. UNIT-IV
  4. What is MobileIP? Mobility in the network layer is termed as Mobile IP.
  5. What are the requirements of Mobile IP? ๏ƒ˜ Compatibility ๏ƒ˜ Transparency ๏ƒ˜ Scalability and Efficiency ๏ƒ˜ Security
  6. Define COA. A COA defines the current location of the MN from an IP point of view. All IP packets sent to the MN are delivered to the COA, not directly to the IP address of the MN. Packet delivery toward the MN is done using a tunnel.
  7. What is Co-located COA? A COA is called co-located if the Mobile Node temporarily acquired an additional IP address which acts as a COA. This address is now topologically correct, and the tunnel endpoint is at the mobile node.
  8. What is encapsulation and decapsulation?

Encapsulation is the mechanism of taking a packet consisting of packet header and data and putting it into the data part of a new packet. The reverse operation, taking a packet out of the data part of another packet, is called decapsulation.

  1. What is the purpose of GRE? GRE allows the encapsulation of packets of one protocol suite into the payload portion of a packet of another protocol suite. The packet of one protocol suite with the original packet header and data is taken and a new GRE header is prepended. Together this forms the new data part of the new packet.
  2. What do you mean by binding request? Any node that wants to know the current location of the mobile node can send a binding request to the home agent/ the home agent can check if the MN has allowed dissemination of its current location. If the HA is allowed to reveal the location it sends back a binding update.
  3. What are the enhancements made in DSDV? ๏ƒ˜ DSDV adds to things to the Distance vector algorithm, ๏ƒ˜ Sequence Number ๏ƒ˜ Damping
  4. What is Route Maintenance? If a node is continuously sending packets via a route. it has to make sure that the route is held upright. As soon as a node detects problems with the current route, it has to find an alternate route.
  5. What is route discovery? A node only tries to discover a route to a destination of it has to send something to this destination and there is currently no known route. If a node needs to discover a route, it broadcasts a route request with a unique identifier and the destination address as parameters.
  6. What is DHCP? DHCP stands for Dynamic Host Configuration Protocol, meant for automatic configuration of IP address.
  7. What is the purpose of DHCPREQUEST?

The COA could be located at the FA, ie., the COA is an IP address of the FA. Thus the FA is the tunnel end point and forwards packets to the MN. many MN using the FA can share this COA as common COA.

  1. Mention the steps to deliver the packet in MobileIP. ๏ƒ˜ Identification of current location of MN ๏ƒ˜ Encapsulation and tunnelling of packets by HA ๏ƒ˜ Decapsulation of packets by FA ๏ƒ˜ MN receiving the packet.
  2. Define tunnelling. Tunnel establishes a virtual pipe for data packets between tunnel entry and tunnel endpoint.Packets entering the tunnel are forwarded inside the tunnel and leave the tunnel unchanged.
  3. Why is routing in multihop adhoc networks complicated? ๏ƒ˜ Traditional routing algorithms will not work efficiently ๏ƒ˜ Centralised approaches will not work ๏ƒ˜ Forwarding a packet in the case of unknown topology is flooding.
  4. What are the two parts of DSR? ๏ƒ˜ Route Discovery ๏ƒ˜ Route Maintenance
  5. What is proactive routing? It maintains fresh lists of destinations and their routes by periodically distributing routing tables throughout the network.
  6. What is Reactive routing? It finds a route on demand by flooding the network with route request packets.
  7. What is multicasting? The delivery of packets from one or more senders to a group of receivers.

UNIT-V

1.What is WAP? Wireless application protocol(WAP) is a common effort of many companies and organizations to set up a framework for wireless and mobile web access using many different transport systems. Eg. GSM, GPRS, UMTS.

  1. ist the interfaces used in WAP architecture ๏ƒ˜ Transport layer service access point ๏ƒ˜ Security service access point ๏ƒ˜ Transaction service access point ๏ƒ˜ Appication service access point
  2. What is the use of WAE? The application layer with the Wireless Application Environment (WAE) offers a framework for the integration of different www and mobile telephony application. 4.What are the benefits of using WTP? It offers several advantages to higher layers, including an improved reliability over datagram services, improved efficiency over connection oriented service, and support for transaction oriented services such as web browsing. 5.How does the WTP achieves reliability? The reliability can be achieved by duplicate removal, retransmission, acknowledgements and unique transaction identifiers. 6.What are the features of WSP? ๏ƒ˜ Session management ๏ƒ˜ Capability management ๏ƒ˜ Content management 7.List the basic features of WML? ๏ƒ˜ The WML includes serveral basic features such as ๏ƒ˜ Text and images
  1. What is WML? Wireless Markup Language is a tag based browsing language for screen management, data input, hyperlinks and navigation support.
  2. What is WML script? omplement to WML. Derived from javascript. Provides general scripting capabilities.
  3. What is WMLBrowser? WMLBrowser is a library that provides several functions typical for a browser,such as prev to go back one card or refresh to update the context of the user interface.
  4. Define WAP WAP is Wireless Application Protocol.It is the basic Objetive of the WAP forum are to bring diverse Internet content and others data service to digital cellular phones and other wireless,mobile terminals.Moreever a protocol suite should enable global wirless communication across different wireless network technologies.All WAP forum solution must be:interoperable,scaleable,efficient,reliable.
  5. What is HTTP? The Hypertext transfer protocol is a stateless, lightweight, application level protocol for data transfer between servers and clients. An HTTP transaction consists of an HTTP request issued by a client and an HTTP response from the server. Stateless means that all HTTP transactions independent of each other.
  6. What is image scaling? If a page contains a true color, high-resolution picture, this picture can be scaled down to fewer colors, lower resolution, or finally to only the title of the picture. The user can decide to download the picture separately. Further one can offer clipping, zooming, or detail studies to users if they are interested in a part of the picture.