16 February 2003 TU/e Computer Science, System Architecture and Networking 1 Communication media Thanks to A. Tanenbaum

16 February 2003 TU/e Computer Science, System Architecture and Networking 2 Fourier Coefficients

16 February 2003 TU/e Computer Science, System Architecture and Networking 3 Bandwidth-Limited Signals A binary signal and its root-mean-square Fourier amplitudes. (b) – (c) Successive approximations to the original signal.

16 February 2003 TU/e Computer Science, System Architecture and Networking 4 Bandwidth-Limited Signals (2) (d) – (e) Successive approximations to the original signal.

16 February 2003 TU/e Computer Science, System Architecture and Networking 5 Twisted Pair (a) Category 3 UTP. (b) Category 5 UTP.

16 February 2003 TU/e Computer Science, System Architecture and Networking 6 Coaxial Cable A coaxial cable.

16 February 2003 TU/e Computer Science, System Architecture and Networking 7 Fiber Optics (a) Three examples of a light ray from inside a silica fiber impinging on the air/silica boundary at different angles. (b) Light trapped by total internal reflection.

16 February 2003 TU/e Computer Science, System Architecture and Networking 8 Fiber Optic Networks A fiber optic ring with active repeaters.

16 February 2003 TU/e Computer Science, System Architecture and Networking 9 Fiber Optic Networks (2) A passive star connection in a fiber optics network.

16 February 2003 TU/e Computer Science, System Architecture and Networking 10 The Electromagnetic Spectrum The electromagnetic spectrum and its uses for communication.

16 February 2003 TU/e Computer Science, System Architecture and Networking 11 Politics of the Electromagnetic Spectrum The ISM bands in the United States.

16 February 2003 TU/e Computer Science, System Architecture and Networking 12 The Local Loop: Modems, ADSL, and Wireless The use of both analog and digital transmissions for a computer to computer call. Conversion is done by the modems and codecs.

16 February 2003 TU/e Computer Science, System Architecture and Networking 13 Data transmission Receiver needs to know about sender duration of each bit length of elements in bits duration of a frame

16 February 2003 TU/e Computer Science, System Architecture and Networking 14 Modems (a) A binary signal (b) Amplitude modulation (c) Frequency modulation (d) Phase modulation

16 February 2003 TU/e Computer Science, System Architecture and Networking 15 Bit encoding(1) Asynchronous data transmission Used for character oriented devices large indeterminate intervals between characters receiver resynchronizes with sender on start and stop bits polarity of stop bit different from polarity of start bit Stop bit(s) Start bit

16 February 2003 TU/e Computer Science, System Architecture and Networking 16 Bit encoding(2) (a) Binary encoding, (b) Manchester encoding, (c) Differential Manchester encoding.

16 February 2003 TU/e Computer Science, System Architecture and Networking 17 Modems (2) (a) QPSK. (b) QAM-16. (c) QAM-64.

16 February 2003 TU/e Computer Science, System Architecture and Networking 18 Frequency Division Multiplexing (a) The original bandwidths.(c) The multiplexed channel. (b) The bandwidths raised in frequency.

16 February 2003 TU/e Computer Science, System Architecture and Networking 19 Wavelength Division Multiplexing Wavelength division multiplexing.

16 February 2003 TU/e Computer Science, System Architecture and Networking 20 Time Division Multiplexing The T1 carrier (1.544 Mbps).

16 February 2003 TU/e Computer Science, System Architecture and Networking 21 Time Division Multiplexing (2) Delta modulation.

16 February 2003 TU/e Computer Science, System Architecture and Networking 22 Time Division Multiplexing (3) Multiplexing T1 streams into higher carriers.

16 February 2003 TU/e Computer Science, System Architecture and Networking 23 Code Division Multiple Access (CDMA) Every single bit Xor with individual Walsh code 1 bit is extended to 64 or 128 chips Consequence 64 (128) more bits transmitted Walsh codes are orthogonal So assume two codes A and B then A.B = 0

16 February 2003 TU/e Computer Science, System Architecture and Networking 24 Code Division Multiple Access (CDMA) (2) Example, two stations with Walsh codes A and B A: B: A and B both transmit 1, Xor with Walsh code Addition of signals then gives S = S.A = ( )/8 = 1 S.B = ( )/8 = 1

16 February 2003 TU/e Computer Science, System Architecture and Networking 25 Wireless coding Direct Sequence Spread Spectrum (DSSS) basis for CDMA Frequency Hopping Spread Spectrum (FHSS)

16 February 2003 TU/e Computer Science, System Architecture and Networking 26 Advanced Mobile Phone System (a) Frequencies are not reused in adjacent cells. (b) To add more users, smaller cells can be used.

16 February 2003 TU/e Computer Science, System Architecture and Networking 27 Multiple Access Protocols a)ALOHA b)Carrier Sense Multiple Access Protocols c)Collision-Free Protocols d)Limited-Contention Protocols e)Wavelength Division Multiple Access Protocols f)Wireless LAN Protocols

16 February 2003 TU/e Computer Science, System Architecture and Networking 28 Dynamic Channel Allocation a)Terminals b)Single Channel c)Collision d)Continuous time vs slotted time e)Carrier sense or not

16 February 2003 TU/e Computer Science, System Architecture and Networking 29 Pure ALOHA In pure ALOHA, frames are transmitted at completely arbitrary times.

16 February 2003 TU/e Computer Science, System Architecture and Networking 30 Pure ALOHA (2) Vulnerable period for the shaded frame.

16 February 2003 TU/e Computer Science, System Architecture and Networking 31 Pure ALOHA (3) Throughput versus offered traffic for ALOHA systems.

16 February 2003 TU/e Computer Science, System Architecture and Networking 32 Persistent and Nonpersistent CSMA Comparison of the channel utilization versus load for various random access protocols.

16 February 2003 TU/e Computer Science, System Architecture and Networking 33 Collision detection interval

16 February 2003 TU/e Computer Science, System Architecture and Networking 34 CSMA with Collision Detection CSMA/CD can be in one of three states: contention, transmission, or idle.

16 February 2003 TU/e Computer Science, System Architecture and Networking 35 Collision-Free Protocols The basic bit-map protocol.

16 February 2003 TU/e Computer Science, System Architecture and Networking 36 Collision-Free Protocols (2) The binary countdown protocol. A dash indicates silence.

16 February 2003 TU/e Computer Science, System Architecture and Networking 37 Limited-Contention Protocols Acquisition probability for a symmetric contention channel.

16 February 2003 TU/e Computer Science, System Architecture and Networking 38 Adaptive Tree Walk Protocol The tree for eight stations.

16 February 2003 TU/e Computer Science, System Architecture and Networking 39 Wireless LAN protocols (a) The hidden station problem. (b) The exposed station problem.

16 February 2003 TU/e Computer Science, System Architecture and Networking 40 Wireless LAN Protocols (2) The MACA protocol. (a) A sending an RTS to B. (b) B responding with a CTS to A.

16 February 2003 TU/e Computer Science, System Architecture and Networking 41 Wireless Lan Protocol: CSMA/CA The use of virtual channel sensing using CSMA/CA.

16 February 2003 TU/e Computer Science, System Architecture and Networking 42 Wireless LAN Protocol: CSMA/CA (2) A fragment burst.

16 February 2003 TU/e Computer Science, System Architecture and Networking 43 Ethernet MAC Sublayer Protocol Frame formats. (a) DIX Ethernet, (b) IEEE

16 February 2003 TU/e Computer Science, System Architecture and Networking 44 Ethernet Performance Efficiency of Ethernet at 10 Mbps with 512-bit slot times.

16 February 2003 TU/e Computer Science, System Architecture and Networking 45 IEEE 802.2: Logical Link Control (a) Position of LLC. (b) Protocol formats.

16 February 2003 TU/e Computer Science, System Architecture and Networking 46 The Protocol Stack Part of the protocol stack.

16 February 2003 TU/e Computer Science, System Architecture and Networking 47 The MAC Sublayer Protocol (4) Interframe spacing in

16 February 2003 TU/e Computer Science, System Architecture and Networking 48 The Frame Structure The data frame.

16 February 2003 TU/e Computer Science, System Architecture and Networking 49 Bluetooth Architecture Two piconets can be connected to form a scatternet.

16 February 2003 TU/e Computer Science, System Architecture and Networking 50 Bridges from 802.x to 802.y (2) The IEEE 802 frame formats. The drawing is not to scale.