1. C OMMUNICATIONS I SSUES Professor Saad Haj Bakry, PhD, CEng, FIEE N ETWORK A RCHITECTURE

2. C ONTENTS Saad Haj Bakry Network Architecture Communications Issues S IGNALS M ODULATION C HANNEL S F LOW S UGGESTED W ORK

3. S IGNALS Saad Haj Bakry Network Architecture S IGNALS C HARACTERISTICS F OURIER E XPANSION N OISE S INUSOIDAL S IGNALS Communications Issues / Signals F OURIER T RANSFORM F REQUENCY S PECTRUM I NFORMATION S IGNALS R ATIOS: dB B AUD V (bps) D IGITAL S IGNALS F REQUENCY T RANSLATION

4. S IGNAL C HARACTERISTICS O BJECTIVES: Represent Information (Voice / Data / Image) Perform a Task (Signalling / RADAR) Saad Haj Bakry Network ArchitectureCommunications Issues / Signals F ORMS: Analog / Digital D OMAINS: Time / Frequency T IMING: Periodic / Non-Periodic N ATURE: Electrical / Light

5. F OURIER E XPANSION O BJECTIVES: To Represent “ Periodic Signals ” by Simpler Components to Ease Analysis Saad Haj Bakry Network ArchitectureCommunications Issues / Signals F INITE B ANDWIDTH: Considers “ Significant ” Components R ESULT: An “ Infinite ” Set of “ Harmonic ” Sinusoidal Signals and a Constant

6. F OURIER T RANSFORM O BJECTIVES: To Transform “ Non- Periodic Signals ” from the Time Domain to the Frequency Domain (and Vice Versa) to Enable Flexible Signal Analysis Saad Haj Bakry Network ArchitectureCommunications Issues / Signals R ESULTS: The Frequency Function has an “ Infinite Range ” F INITE B ANDWIDTH: Considers “ Significant ” Frequency Components

7. S INUSOIDAL S IGNALS P ERIODIC: T (sec) Saad Haj Bakry Network ArchitectureCommunications Issues / Signals W AVE L ENGTH: L (met) = V.T = V / F I MPORTANCE : Harmonic Components of Signals / Modulation F REQUENCY: F (Hz) = 1 / T V ELOCITY: V (met / sec) A MPLITUDE: A (vol) E FFECTIVE V ALUE: U (vol) = A / sqrt( 2 ) N ORMALIZED P OWER: S (wat) = A 2 / 2

8. F REQUENCY S PECTRUM: 1/4 Saad Haj Bakry Network ArchitectureCommunications Issues / Signals VLF : 3 kHz - 30 kHz (100 km - 10 km) HF : 3 MHz - 30 MHz (100 m - 10 m) Telephone / Ships / Airplanes LF : 30 kHz - 300 kHz (10 km - 1 km) General Navigation MF : 300 kHz - 3 MHz (1 km - 100m) Commercial MW Radio

9. F REQUENCY S PECTRUM: 2/4 Saad Haj Bakry Network ArchitectureCommunications Issues / Signals SHF : 3 GHz - 30 GHz (10 cm - 1 cm) Terrestrial Microwave / Satellites VHF : 30 MHz - 300 MHz (10 m - 1 m) Commercial FM Radio / Police / Airplanes UHF : 300 MHz - 3 GHz (1 m - 1 cm) Television / Cellular VLF : 30 GHz - 300 GHz (1 cm - 1 mm) Railroad / RADAR

10. F REQUENCY S PECTRUM: 3/4 Saad Haj Bakry Network ArchitectureCommunications Issues / Signals VHF B AND: 500 MHz - 1 GHz M ICROWAVE B ANDS K B AND: 18 GHz - 26.5 GHz Ku B AND: 12.4 GHz - 18 GHz X B AND: 8 GHz - 12.4 GHz C B AND: 4 GHz - 8 GHz L B AND: 1 GHz - 2 GHz Ka B AND: 26.5 GHz - 40 GHz S B AND: 2 GHz - 4GHz

11. F REQUENCY S PECTRUM: 4/4 Saad Haj Bakry Network ArchitectureCommunications Issues / Signals L IGHT W AVES: 1 kGHz - 10 MGHz (Infrared - Ultraviolet) L IGHT B ANDS / S PECIAL R AYS X R AY: 1 GGHz S EEN L IGHT: 428.5 kGHz - 750 kGHz (Red - Violet) G AMA R AY: 100 GGHz C OSMIC R AY: 100 kGGGHz = 10 32

12. D IGITAL S IGNALS Saad Haj Bakry Network ArchitectureCommunications Issues / Signals Noise Separation by ReShaping Noise Cannot be Separated from the Signals at Repeaters and at Destinations A NALOG: C ONTINUOUS C HANGE D IGITAL: D ISCRETE C HANGE Digital Processing B UT: Wider Band

13. I NFORMATION S IGNALS: V OICE Saad Haj Bakry Network ArchitectureCommunications Issues / Signals F REQUENCY: 0 - 15 kHz T ELEPHONE V OICE: 300 Hz - 3.4 kHz Spacing: 4 kHz A NALOG S AMPLING: 8 k (sample) Q UANTIZATION: 256 levels C ODING: Digital Signal 64 kbps PCM: Digital Telephone Voice

14. I NFORMATION S IGNALS: P ICTURE Saad Haj Bakry Network ArchitectureCommunications Issues / Signals A NALOG TV F REQUENCY B ANDWIDTH: System Dependent (4 - 10 MHz) Mostly: 6 MHz D IGITAL TV: System Dependent Usually: 45 Mbps (T3) (Satellite Transponder) P ROBLEM: Large Bandwidth (Compression)

15. I NFORMATION S IGNALS: D ATA Saad Haj Bakry Network ArchitectureCommunications Issues / Signals B INARY R EPRESENTATION: Binary Digit On / Off (bit =0/1) = 2 States ASCII C ODE: Character = 7 bits 128 states AI5 C ODE: ASCII + 1 bit (parity bit / 256 states) EBCDIC C ODE: 8 bits B AUDOT C ODE: 5 bits (32 states)

16. F REQUENCY T RANSLATION Saad Haj Bakry Network ArchitectureCommunications Issues / Signals B ASEBAND S IGNAL: A Signal in its Original Frequency [0 - f s ] O BJECTIVE: Moving a Signal to a Higher Frequency [(f c )-(f c +f s )] A DVANTAGES: Channel Assignment & Multiplexing (Broadband Signals) Better Radiation at Higher Frequency A DVANTAGES: Channel Assignment & Multiplexing (Broadband Signals) Better Radiation at Higher Frequency M ETHOD: Mixing with a Sinusoidal Signal

17. B AUD VERSUS bps : 1/2 Saad Haj Bakry Network Architecture Communications Issues / Signals 2 S TATES P ER S LOT: 1 bit (0/1) 2 S TATES P ER S LOT: 1 bit (0/1) 4 S TATES P ER S LOT: 2 bit (00/01/10/11) 4 S TATES P ER S LOT: 2 bit (00/01/10/11) 8 S TATES P ER S LOT: 3 bit (000/001/010/011/ 100/101/110/111) F ORM OF C OMPRESSION P RACTICAL E XAMPLE: PSK

18. B AUD VERSUS bps: 2/2 Saad Haj Bakry Network Architecture Communications Issues / Signals R ATE [ bps] = R ATE [ BAUD]. Ln 2 (No. of states) C ASE S TUDY: R ATE [ BAUD] = 9600 2 States Rate (bps) = 9600 bps 4 States Rate (bps) = 19.2 kbps 8 States Rate (bps) = 28.8 kbps

19. I NTERNAL N OISE Saad Haj Bakry Network Architecture Communications Issues / Signals J HONSON / T EMPERATURE / W HITE: All Frequencies S HOT N OISE / P OWER S UPPLY: Hum Noise Partition Noise O THERS: Coupling Transformers Magnetic Fields

20. E XTERNAL N OISE Saad Haj Bakry Network Architecture Communications Issues / Signals A TMOSPHERIC: Thunderstorms (Impulsive) M AN M ADE: Power Lines Electric Motors Switching E XTRATERRESTRIAL: Sun / Stars M ULTIPLE T RANSMISSION P ATH

21. R ATIOS / dB Saad Haj Bakry Network Architecture Communications Issues / Signals G AIN / L OSS / S IGNAL-TO- N OISE RATIO = POWER (out) / POWER (in) RATIO = POWER (signal) / POWER (noise) RATIO (dB) = 10 log 10 (RATIO) RATIO = 0.1, 1, 10, 100 RATIO (dB) = -10, 0, 10, 20

22. C HANNELS Saad Haj Bakry Network Architecture N ATURE P HYSICAL U SE Communications Issues / Channels C APACITY VERSUS B ANDWIDTH A NALOG ISDN / SONET / SDH D IGITAL

23. P HYSICAL Saad Haj Bakry Network Architecture W IRE: C OPPER Twisted Pair / Cables O PTICAL F IBER (Low Noise) P ROPAGATION 200,000 km / sec Communications Issues / Channels W IRELESS: T ERRESTRIAL Ground Environment S ATELLITE / S PACE Geo-stationary Altitude: 36,000 km P ROPAGATION 300,000 km / sec

24. N ATURE Saad Haj Bakry Network Architecture S INGLE: ( O NE W AY) 2 W IRES ( B ASEBAND) / F REQUENCY ( S UB) B AND / T IME S LOTS Communications Issues / Channels D OUBLE: ( T WO W AY) 4 W IRES ( B ASEBAND) / 2 F REQUENCY ( S UB) B ANDS / 2 S LOT S ETs M ULTIPLE: (x) 2 Wire B ASEBAND / (x) Frequency SubBands B ROADBAND / (x) S LOT S ETS

25. C APACITY VERSUS B ANDWIDTH Saad Haj Bakry Network Architecture Communications Issues / Channels C [bps] = BW [Hz]. ln 2 (1+(P s /P n )) BW [Hz] = C [bps] / ln 2 (1+(P s /P n )) S HANNON I NFORMATION T HEORY How Can (ln 2 ) be transformed to (log 10 ) to ease computation

26. A NALOG Saad Haj Bakry Network Architecture B ASE C HANNEL: Voice Grade 4 kHz Communications Issues / Channels G ROUP: 12 B ASE = 48 kHz S UPER G ROUP: 5 G ROUP= 60 B ASE = 240 kHz M ASTER G ROUP: 5 S UPER G ROUP = 25 G ROUP 300 B ASE = 1.2 MHz

27. D IGITAL: ITU Saad Haj Bakry Network Architecture B ASE C HANNEL: Voice Grade / PCM 64 kbps Communications Issues / Channels E-1 : 30 (+) PCM 2.048 Mbps E-2 : 120 (+) PCM 8.448 Mbps E-3 : 480 (+) PCM 34.368 Mbps 1920 (+) PCM 139.264 Mbps 7860 (+) PCM / 565.148 Mbps

28. D IGITAL: NA Saad Haj Bakry Network Architecture B ASE C HANNEL: Voice Grade / PCM 64 kbps Communications Issues / Channels T-1 : 24 (+) PCM 1.544 Mbps T-1(C) : 48 (+) PCM 3.152 Mbps T-2 : 96 (+) PCM 6.312 Mbps T-4 : 4032 (+) PCM / 274.176 Mbps T-3 : 672 (+) PCM 44.736 Mbps

29. ISDN Saad Haj Bakry Network Architecture B ASE C HANNEL: B = 64 kbps D = 16 kbps (Basic Rate: Individual) D = 64 kbps (Primary Rate: Organization) Communications Issues / Channels B ASIC R ATE: 2B + D 144 kbps P RIMARY R ATE : 23B + D = (24B) 1.544 Mbps H0 : 6B 384 kbps H11 : 24B 1.536 Mbps H12 : 30B 1.92 Mbps H4 : 9720B 622.08 Mbps

30. SONET / SDH Saad Haj Bakry Network Architecture OC-1 : 51.840 Mbps Communications Issues / Channels OC-3 / STM-1 : 155.250 Mbps OC-48 : 2.488 Gbps OC-12 / STM-4 : 622.08 Mbps

31. U SE Saad Haj Bakry Network Architecture D IAL U P: Normal Use of Telephone Lines (Individuals) Communications Issues / Channels L EASE: Dedicated Hot Link of Any Capacity (Organizations) S HARE: Such as in Virtual Private Networks

32. F LOW Saad Haj Bakry Network Architecture P ARALLEL / S ERIAL Communications Issues Flow D IRECTION A SYNCHRONOUS S YNCHRONOUS

33. P ARALLEL / S ERIAL Saad Haj Bakry Network Architecture Communications Issues Flow 0 0 1 1 0 0 1 1 0 0 0 0 1 1 1 1 S ERIAL: O NE C HANNEL P ARALLEL: M ULTIPLE C HANNELS

34. D IRECTION Saad Haj Bakry Network Architecture S IMPLEX: One Direction TRANSMITTER (T) Single RECEIVER (R) S IMPLEX: One Direction TRANSMITTER (T) Single RECEIVER (R) Communications Issues / Flow H ALF D UPLEX: One at a Time (T) / (R) Single (T) / (R) H ALF D UPLEX: One at a Time (T) / (R) Single (T) / (R) F ULL D UPLEX: Two Simultaneously (T) / (R) Double (T) / (R) F ULL D UPLEX: Two Simultaneously (T) / (R) Double (T) / (R)

35. A SYNCHRONOUS Saad Haj Bakry Network Architecture Communications Issues Flow 0 0 1 1 0 0 1 1 0 0 0 0 1 1 1 1 S S S TART S TOP D ATA: 1 Character I NTERMITTENT F LOW High Control Overheads: 20 %

36. S YNCHRONOUS Saad Haj Bakry Network Architecture Communications Issues Flow S YNC. D ATA: 1 Block C ONTINUOUS F LOW Lower Control Overheads S S S S

37. M ODULATION Saad Haj Bakry Network Architecture M ODEMS P RINCIPLES Communications Issues / Modulation A NALOG P ULSE D IGITAL

38. P RINCIPLES Saad Haj Bakry Network Architecture O BJECTIVE: Transferring Information Signals to a New Form Suitable for the Target Communication System Communications Issues / Modulation C ONCEPT: Changing Some Features of a “ CARRIER ” Signal (New Form) According to the Information Signal to be “ CARRIED ” F EATURES: A MPLITUDE P HASE F REQUENCY ( C ODING) F EATURES: A MPLITUDE P HASE F REQUENCY ( C ODING)

39. A NALOG Saad Haj Bakry Network Architecture I NFORMATION S IGNALS: A NALOG C ARRIER S IGNAL: A NALOG (Sinusoidal) I NFORMATION S IGNALS: A NALOG C ARRIER S IGNAL: A NALOG (Sinusoidal) Communications Issues / Modulation M ETHODS: A MPLITUDE M ODULATION ( AM ) Radio / TV Picture / Telephone P HASE M ODULATION ( PM ) F REQUENCY M ODULATION ( FM ) Radio / TV Voice / Mobile M ETHODS: A MPLITUDE M ODULATION ( AM ) Radio / TV Picture / Telephone P HASE M ODULATION ( PM ) F REQUENCY M ODULATION ( FM ) Radio / TV Voice / Mobile

40. P ULSE Saad Haj Bakry Network Architecture I NFORMATION S IGNALS: A NALOG C ARRIER S IGNAL: P ULSE (Digital) I NFORMATION S IGNALS: A NALOG C ARRIER S IGNAL: P ULSE (Digital) Communications Issues / Modulation M ETHODS: P ULSE AM ( PAM ) Sampling Analog Information Signals P ULSE C ODE M OD. ( PCM ) Transforming Analog Information Signals to Digital M ETHODS: P ULSE AM ( PAM ) Sampling Analog Information Signals P ULSE C ODE M OD. ( PCM ) Transforming Analog Information Signals to Digital

41. D IGITAL Saad Haj Bakry Network Architecture I NFORMATION S IGNALS: D IGITAL C ARRIER S IGNAL: A NALOG (Sinusoidal) I NFORMATION S IGNALS: D IGITAL C ARRIER S IGNAL: A NALOG (Sinusoidal) Communications Issues / Modulation M ETHODS: A MPLITUDE S HIFT K EYING ( ASK ) P HASE S HIFT K EYING ( PSK ) F REQUENCY S HIFT K EYING ( FSK ) Transforming Digital Information Signals to Analog (Example: MODEM S) M ETHODS: A MPLITUDE S HIFT K EYING ( ASK ) P HASE S HIFT K EYING ( PSK ) F REQUENCY S HIFT K EYING ( FSK ) Transforming Digital Information Signals to Analog (Example: MODEM S)

42. M ODEM: E XAMPLE Saad Haj Bakry Network Architecture Communications Issues / Modulation C (kbps) M ODEM Digital Analog BW = 4 kHz Capacity “ C ” Depends on the Channel “ BW ” & MODEM Capaity “ C ” Can be Increased by Multilevel (BAUD) Signals / Compression (e.g. PSK) FSK S END C HANNEL: f(0) = 1180 Hz (0 bit) f(1) = 980 Hz (1 bit) FSK R ECEIVE C HANNEL: f(0) = 1850 Hz (0 bit) f(1) = 1650 Hz (1 bit)

43. M ODEM: C ONNECTION Saad Haj Bakry Network Architecture Communications Issues / Modulation PC-MODEM (RS-232) Serial Interface (25 pins) D ATA: 2 / 3 (14 /16) C ONTROL: 4 / 5 / 6 / 8 / 20 / 21 / 22 / 23 (12 /13 /19) T IMING: 24 / 15 / 17 G ROUND: 1 / 7 (Return) R ESERVED: (9 / 10) U NASSIGNED: ( 11 / 18 / 25)

44. S UGGESTED W ORK: A NALYSIS Saad Haj Bakry Network Architecture Communications Issues / Work B AUD / L EVELS / bps R ATIO ( dB ) Versus R ATIO C / BW / ( P S / P N ) G ENERIC / S PECIFIC I NVESTIGATIONS

45. S UGGESTED W ORK: P RACTICAL Saad Haj Bakry Network Architecture Communications Issues / Work M ODEMS P RACTICAL S YSTEMS & S TANDARDS F LOWS C HANNELS