CS601 Midterm Solved Subjective Part 2

Question: What are regulatory Agencies?

Answer: All communication technology is subject to regulation and laws by government agencies. The purpose is to protect Public Interest by regulating Radio, Television and Cable Communications.

Question: What is the main problem with ASK (amplitude Shift Keying)?

Answer: The main problem with ASK is the noise. Noise usually affected the amplitude so it is most affected by Noise.

Question: What are the basic components of a data communication system ?

Answer: There are five basic components of a data communication. These are as follows:- 1) message 2) sender 3) receiver 4) medium 5) protocol

Question: How can I define Data communication?

Answer: Data communication is the name of a communication between computers. More specifically, the exchange of data in the form 0's and 1's between two devices (computers) via some form of the transmission medium. Nowadays, data communication between computers also supports digital speech telephone and videophone, thus following direct communication between people. Question: What is PCMCIA?

Answer: PCMCIA (Personal Computer Memory Card International Association) is an international standards body and trade association with over 100 member companies that was founded in 1989 to establish standards for Integrated Circuit cards and to promote interchangeability among mobile computers where ruggedness, low power, and small size were critical. As the needs of mobile computer users has changed, so has PCMCIA. By 1991, PCMCIA had defined an I/O interface for the same 68 pin connector initially used for memory cards. At the same time, the Socket Services Specification was added and was soon followed by the Card Services Specifcation as developers realized that common software would be needed to enhance compatibility.

Question: Will VoIP work with DSL?

Answer: Yes, VoIP works with DSL. Many of the phone companies currently providing DSL and landline phone services are in the process of unbundling DSL and phone services.

Question: What is attenuation?

Answer: Attenuation is signal loss due to the diminishing availability of signal energy, or signal power. As a analog or digital signal traverses across a medium, it fades. High attenuation may lead to the inability to recover the signal on the far end. Signal repeaters may be used on the transmission path to periodically boost the signal strength. Baseband transmission is extremely limited to attenuation. Broad-band much less so, In addition, wireless communications is much less susceptible to attenuation that is wire-line communications such as x-DSL or cable modems.

Question: What is difference between logical address and physical address?

Answer: The OSI model is a good place to start to learn more about the differences between physical and logical addressing. Think of the physical address as the 48-bit MAC address that manufacturers encode in their network interface cards (NICs). This type of address is unique, referred to as the Ethernet or hardware address, and cannot be changed. The MAC or Ethernet address is associated with Layer 2 (data Link) of the OSI Model. The logical address is a 32-bit IP address that is not embedded in the network card but it is assigned to it for the purpose of routing between networks. This type of address operates at Layer 3 (network) of the OSI Model.

Question: What is the differences between OSI and TCP/IP Model?

Answer: The ISO/OSI protocol is a 7 layer reference model that was designed after TCP/IP model, which only has 4 layers. That said, the differences between the two are only minor. The layers of the OSI Protocol Stack are as follows: 7. Application: end user services such as email 6. Presentation: data problems and data compression 5. Session: authentication and authorization 4. Transport: guarantee end-to-end delivery of packets 3. Network: packet routing 2. Data Link: transmit and receive packets 1. Physical: The physical connection or cable itself. Of these 7 layers, the 4 layers the TCP/IP Protocol Stack use are as follows: 5. Application: authentication, compression, and end user services 4. Transport: handles the flow of data between systems and provides access to the network for applications via the BSD socket library 3. Network: packet routing 2. Link: Kernel OS/device driver interface to the network interface on the computer. The main differences between OSI and TCP/IP are: The application layer in TCP/IP handles the responsibilities of layers 5,6, and 7 in the OSI model. The transport layer in TCP/IP does not always guarantee reliable delivery of packets as the transport layer in the OSI model does. So as you can see there is not too much difference between the models. In terms of software implementation TCP/IP looks like this: Application Layer: some of the applications covered are SMTP (mail), Telnet, FTP, Rlogin, NFS, NIS, and LPD. Transport Layer: the transport uses two protocols, UDP (User Datagram Protocol) and TCP, which does not guarantee packet delivery and applications which use this must provide their own means of verifying delivery. TCP guarantees delivery of packets to the applications that use it. Network Layer: the network layer is concerned with packet routing and used low level protocols such as ICMP, IP, and IGMP. Link Layer: the link layer is concerned with the actual transmittal of packets as well as IP to Ethernet address translation. This layer is concerned with Arp, the device driver and Rarp. Question: What is Tx and Rx?

Answer: Tx is the abrivation used for transmission/ transmitor and Rx is reciever.

Question: What do we mean by wireless networking?

Answer: The term wireless networking refers to technology that enables two or more computers to communicate using standard network protocols, but without network cabling. Strictly speaking, any technology that does this could be called wireless networking. The current buzzword however generally refers to wireless LANs.

Question: What is PDU in OSI Model?

Answer: Normally a communication request originates at the highest layer (Application Layer). The request is passed down through the lower layers in the form of a packet called a protocol data unit (PDU). Layers in the protocol stack communicate with their adjacent layers via one or more Service Access Points (SAP). Each succeeding layer in the stack adds its own information to the PDU that will be read by its counterpart (peer) layer on the receiving system. Once the data arrives at the lower layers, the PDU is encoded into data frames and placed onto the cable for transmission. The data frames make their way to the receiving system and the entire process is reversed as the PDU makes its way up the protocol stack. As it moves up the stack, each layer "unwrap" the PDU and receives the information from its peer layer on the sending system.

Question: What is the difference between WAP and GPRS?

Answer: Wireless Application Protocol, a secure specification that allows users to access information instantly via handheld wireless devices such as mobile phones. Wireless Application Protocol (or WAP) is envisioned as a comprehensive and scalable protocol designed to use with mobile phones