voice and data communications

... the data And the receiver of data may wish to be assured that the received data have not been altered in transit and that the data actually come from the purported sender Finally, a data communications ... transmit and process all types of data and information Both the technology and the technical standards or- ganizations are driving toward integrated public systems that make virtually all data and ... wide area voice and data networks Wireless networks provide advantages in the areas of mobility and ease of installation and configuration Chapters 14 and 17 deal with wireless WANs and LANs,

Ngày tải lên: 13/09/2012, 10:21

... Look at Video and Data Services.’’ Video and data are the second and third legs of the three-legged IP-enabled stool. Recently, we examined Voice over IP, which is the other leg. And as we modernize ... COMMU- NICATIONS: A LOOK AT VIDEO AND DATA SERVICES WEDNESDAY, APRIL 20, 2005 H OUSE OF R EPRESENTATIVES , C OMMITTEE ON E NERGY AND C OMMERCE , S UBCOMMITTEE ON T ELECOMMUNICATIONS AND THE I NTERNET , Washington, ... OF COMMUNICA- TIONS: A LOOK AT VIDEO AND DATA SERVICES HEARING BEFORE THE SUBCOMMITTEE ON TELECOMMUNICATIONS AND THE INTERNET OF THE COMMITTEE ON ENERGY AND COMMERCE HOUSE OF REPRESENTATIVES ONE

Ngày tải lên: 18/02/2014, 00:20

... 1Chapter 2: Fundamentals of Data and SignalsTRUE/FALSE 1 The terms “data” and “signal” mean the same thing 2 By convention, the minimum and maximum values of analog data and signals are presented ... network It is important to understand that the terms “data” and “signal” do not mean the same thing, and that in order for a computer network to transmit data, the data must first be converted into ... modulates digital data onto an analog signal and then demodulates the analog signal back to digital data is a 26 Three currently popular modulation techniques for encoding digital data and transmitting

Ngày tải lên: 19/10/2017, 16:27

... Trang 1DATA COMMUNICATIONSAND NETWORKING Second Edition FM Page i Wednesday, February 23, 2000 2:30 PM Trang 2FM Page ii Wednesday, February 23, 2000 2:30 PMTrang 3DATA COMMUNICATIONSAND NETWORKING ... Choice 60 Exercises 63 Chapter 4 Signals 65 4.1 ANALOG AND DIGITAL 65 Analog and Digital Data 66 Analog and Digital Signals 66 4.2 APERIODIC AND PERIODIC SIGNALS 66 Periodic Signals 67 Aperiodic ... Supplementary Services 472 16.2 HISTORY 472 Voice Communication over Analog Networks 472 Voice and Data Communication over Analog Networks 472 Analog and Digital Services to Subscribers 473 Integrated

Ngày tải lên: 24/10/2017, 13:15

... with enterprise-wide and departmental-level applications, business processes, and workflows 1.5 Voice communications, data communications, image communications, and video communications are all ... business campus) and long distance, has been growing at a high and steady rate for decades Network traffic is no longer limited to voice and data and increasingly includes image and video Increasing ... are stored Data being captured and stored includes documents, e-mail messages, voice- mail messages, text messages, and social media data Other data sources being captured, transmitted, and stored

Ngày tải lên: 08/11/2019, 14:53

... with enterprise-wide and departmental-level applications, business processes, and workflows 1.5 Voice communications, data communications, image communications, and video communications are all ... business campus) and long distance, has been growing at a high and steady rate for decades Network traffic is no longer limited to voice and data and increasingly includes image and video Increasing ... communications (UC) Whereas convergence focuses on the merger of fundamental voice, video, and data communications facilities and the resulting ability to support multimedia applications, UC focuses

Ngày tải lên: 31/01/2020, 15:51

... whatever  form  is  agreed  upon  by  the  parties  creating  and  using  the  data.  Data  communications  are  the  exchange  of  data  between  two  devices  via  some  form  of  transmission medium such as a wire cable.  ... Topics discussed in this section: Components Data Representation Data Flow 1.2 Figure 1.1  Five components of data communication 1.3 Figure 1.2  Data flow (simplex, half­duplex, and full­duplex) 1.4 1-2 NETWORKS ... PROTOCOLS AND STANDARDS In this section, we define two widely used terms:  protocols  and  standards.  First,  we  define  protocol,  which  is  synonymous with rule. Then we discuss standards, which 

Ngày tải lên: 23/09/2020, 13:31

... multinational  body  dedicated  to  worldwide agreement on international standards. An ISO  standard  that  covers  all  aspects  of  network  communications  is  the  Open  Systems  Interconnection  (OSI) model. It was first introduced in the late 1970s.  ... transport,  and  application.  However,  when  TCP/IP  is  compared  to  OSI,  we  can  say  that  the  TCP/IP  protocol  suite  is  made  of  five  layers:  physical,  data link, network, transport, and application ... data link, network, transport, and application Topics discussed in this section: Physical and Data Link Layers Network Layer Transport Layer Application Layer 2.28 Figure 2.16  TCP/IP and OSI model 2.29 2-5 ADDRESSING Four levels of addresses are used in an internet employing 

Ngày tải lên: 23/09/2020, 13:31

... digital  data digital  data  refers  to  information  that  has  discrete  states.  Analog  data  take  on  continuous values. Digital data take on discrete values. Analog and Digital Data Analog and Digital Signals ... 88Figure 3.30  Two cases of SNR: a high SNR and a low SNR Trang 893-5 DATA RATE LIMITS A very important consideration in data communications  is how fast we can send data, in bits per second, over a  channel. Data rate depends on three factors: ... Analog and Digital Signals Periodic and Nonperiodic Signals Topics discussed in this section: Trang 4Note Data can be analog or digital Analog data are continuous and take continuous values. Digital data have discrete

Ngày tải lên: 23/09/2020, 13:32

... block  coding and scrambling may or may not be needed. Trang 3Figure 4.1  Line coding and decoding Trang 4Figure 4.2  Signal element versus data element Trang 5A  signal  is  carrying  data  in  ... 14NRZ-L and NRZ-I both have an average signal rate of N/2 Bd. Note Trang 15NRZ-L and NRZ-I both have a DC component problem. Note Trang 16A system is using NRZ­I to transfer 10­Mbps data. What  ... 16A system is using NRZ­I to transfer 10­Mbps data. What  are the average signal rate and minimum bandwidth? Trang 17Figure 4.7  Polar RZ scheme Trang 18Figure 4.8  Polar biphase: Manchester and differential Manchester schemes Trang 21In

Ngày tải lên: 23/09/2020, 13:32

... 5.29 Note The total bandwidth required for AM can be determined from the bandwidth of the audio signal: BAM = 2B 5.30 Figure 5.17  AM band allocation 5.31 Note The total bandwidth required for ... signal  elements do we need? Solution In this example, S = 1000, N = 8000, and r and L are unknown We find first the value of r and then the value of L 5.7 Figure 5.3  Binary amplitude shift keying ... 5.3 We  have  an  available  bandwidth  of  100  kHz  which  spans  from  200  to  300  kHz.  What  are  the  carrier  frequency and the bit rate if we modulated our data by  using ASK with d = 1?

Ngày tải lên: 23/09/2020, 13:32

... 2Bandwidth utilization is the wise use of available bandwidth to achieve Trang 36-1 MULTIPLEXING Whenever  the  bandwidth  of  a  medium  linking  two  devices  is  greater  than  the  bandwidth  ... allows  the  simultaneous  transmission  of  multiple  signals  across  a  single  data  link. As data and telecommunications use increases, so  does traffic. Trang 4Figure 6.1  Dividing a link into channels ... 9Figure 6.5  FDM demultiplexing example Trang 10Assume  that a voice channel occupies a bandwidth of 4  kHz. We need to combine three voice channels into a link  with a bandwidth of 12 kHz, from 20 to 32 kHz. Show the 

Ngày tải lên: 23/09/2020, 13:32

... Topics discussed in this section: Bandwidth Sharing CM and CMTS Data Transmission Schemes: DOCSIS 9.30 Figure 9.16  Division of coaxial cable band by CATV 9.31 Note Downstream data are modulated using ... carry  frequencies  between 300 and 3300 Hz, giving them a bandwidth of  3000 Hz. All this range is used for transmitting voice,  where  a  great  deal  of  interference  and  distortion  can  be accepted without loss of intelligibility ... exchange carriers and competitive local exchange carriers 9.4 Figure 9.2  Switching offices in a LATA 9.5 Figure 9.3  Point of presences (POPs) 9.6 Note The tasks of data transfer and signaling are

Ngày tải lên: 23/09/2020, 13:33

... but it knows that the incoming data must be delivered to  the IP protocol because the NCP protocol used before the  data transfer was IPCP After data transfer, the user then terminates the data link  connection,  ... most  important  responsibilities  of  the  data  link  layer  are  flow  control  and  error  control.  Collectively,  these functions are known as data link control Topics discussed in this section: ... chosen two options (not shown in the figure): using PAP  for  authentication  and  suppressing  the  address  control  fields.  Frames  3  and  4  are  for  authentication.  Frames  5  and 6 establish the network layer connection using IPCP

Ngày tải lên: 23/09/2020, 13:34

... functions of the physical layer and the data link layer  of major LAN protocols. Data Link Layer Physical Layer Topics discussed in this section: Trang 3Figure 13.1  IEEE standard for LANs Trang 4Figure 13.2  HDLC frame compared with LLC and MAC frames ... 22Table 13.1  Summary of Standard Ethernet implementations Trang 2313-3 CHANGES IN THE STANDARD The  10­Mbps  Standard  Ethernet  has  gone  through  several  changes  before  moving  to  the  higher  data  rates.  ... other high­data­rate LANs.  Bridged Ethernet Switched Ethernet Full­Duplex Ethernet Topics discussed in this section: Trang 24Figure 13.14  Sharing bandwidth Trang 25Figure 13.15  A network with and without a bridge

Ngày tải lên: 23/09/2020, 13:34

... SONET LAYERS The SONET standard includes four functional layers:  the  the  photonic photonic , the  section , the  section , the  line , the  line , and the  path , and the  path  layer.  They correspond to both the physical and the data link  ... , and the  path  layer.  They correspond to both the physical and the data link  layers. Trang 7SONET defines four layers: path, line, section, and photonic. Note Trang 8Figure 17.2  SONET layers compared with OSI or the Internet layers ... SONET frame can carry a digitized voice channel. Note Trang 15Example 17.1Trang 16Example 17.2Trang 17In SONET, the data rate of an STS-n signal is n times the data rate of an STS-1 signal. Note

Ngày tải lên: 23/09/2020, 13:35

... request  and  reply  packets encapsulated in Ethernet frames. Solution Figure  21.5  shows  the  ARP  request  and  reply  packets.  Note that the ARP data field in this case is 28 bytes, and  that  ... The unnumbered line after the command shows that the  destination is 153.18.8.1. The packet contains 38 bytes: 20  bytes of IP header, 8 bytes of UDP header, and 10 bytes of  application  data.  The  application  data  ... message.  We  randomly  chose  the  identifier  to  be  1  and  the  sequence  number  to  be  9.  The  message  is  divided  into  16­bit  (2­byte)  words.  The  words are added and the sum is complemented. Now the 

Ngày tải lên: 23/09/2020, 13:36

... packet and forwards it to all interested interfaces 22.77 Note PIM-DM is used in a dense multicast environment, such as a LAN 22.78 Note PIM-DM uses RPF and pruning and grafting strategies to handle ... guarantees that each destination receives one and only one copy of the packet 22.72 Figure 22.43  RPF, RPB, and RPM 22.73 Note RPM adds pruning and grafting to RPB to create a multicast shortest ... Delivery, Forwarding, and Routing 22.1 Copyright © The McGraw­Hill Companies, Inc. Permission required for reproduction or display 22-1 DELIVERY The  network  layer  supervises  the  handling  of  the 

Ngày tải lên: 23/09/2020, 13:37

... Trang 15Figure 28.7  Data type Trang 16Table 28.1  Data types Trang 17Figure 28.8  Conceptual data types Trang 18Figure 28.9  Encoding format Trang 19Table 28.2  Codes for data types Trang 20Figure 28.10  Length format ... is handled by SMI. ❏ Both tasks need variable declarations In network management this is handled by MIB. ❏ Both tasks have actions performed by statements In network management this is handled ... general rules for naming objects, defining object types (including range and length), and showing how to encode objects and values SMI does not define the number of objects an entity should manage

Ngày tải lên: 23/09/2020, 13:39

... RTP allows only one type of message, one that carries  data from the source to the destination. In many cases,  there is a need for other messages in a session. These  messages  control  the  flow  and  quality  of  data  and  allow the recipient to send feedback to the source ... applications 29.5 29-1 DIGITIZING AUDIO AND VIDEO Before  audio  or  video  signals  can  be  sent  on  the  Internet,  they  need  to  be  digitized.  We  discuss  audio  and video separately Topics discussed in this section: ... Internet 29.7 29-2 AUDIO AND VIDEO COMPRESSION To  send  audio  or  video  over  the  Internet  requires  compression.  In  this  section,  we  discuss  audio  compression first and then video compression

Ngày tải lên: 23/09/2020, 13:39