VSAT Technology and Applications Prepared for the Israel

VSAT Technology and Applications Prepared for the Israel Amateur Radio Club By: 4 X 1 DA – Rich Harel November 14, 2002 1

Agenda Introduction to Gilat Satellite Networks What is a VSAT? Typical VSAT Applications Satellite Communication Fundamentals VSAT Network Architectures Access Schemes Network Components Network Management VSATs Applications in Amateur Radio Demonstration of Equipment Summary 2

Gilat Satellite Networks Ltd. 3

Gilat Satellite Networks Ltd. Founded in 1987 Over 950 employees worldwide Core technology: End-to-end two-way satellite broadband platform Sales, service and support offices worldwide Traded on NASDAQ (GILTF) since 1993 Revenues in 2001: $389 M Headquartered in Petech Tikva, Israel Three Regional Headquarters: Spacenet (North America) Mclean, VA Gilat Latin America – Sunrise, FL Gilat Asia, Pacific Rim and Africa – Petach Tikva, Israel 4

What is a VSAT? VSAT = Very Small Aperture Terminal Satellite-based Wide Area Network (WAN), with centrally managed hub Remote site: less than 1. 2 m dish antenna Multi-service platform: Data, telephony and multimedia communications Optimal for continent-wide networks of hundreds or thousands of units Small networks integrated in shared hub service Large networks, in the tens of thousands, for Internet access 5

VSAT Advantages Full or partial independence from terrestrial infrastructure Cost savings over terrestrial lines Nationwide reach, distance-independent Network management from a single point Quick deployment, network flexibility Consistent and rapid response time Increased network availability and reliability Inherent broadcast / multicast platform 6

Unicast, Multicast, Broadcast Each Unicast Packet is Numbered and Acknowledged 7

Unicast, Multicast, Broadcast Multicasts Packets are Not Acknowledged Different Data Steams can be sent simultaneously to many users 8

Unicast, Multicast, Broadcast Packets are sent to all users in the Network Simultaneously Broadcasts are Not Acknowledged VSAT Networks can use Reliable Broadcast Protocols and applications that are based on NACK’s, not ACK’s 9

VSAT Speeds Compared to Dialup Modem The name of the game is THROUGHPUT ! A 56 K Modem will typically connect at speeds of only 43 Kbps 10

VSAT Markets Enterprise Retail; Oil & Gas; Banking; Government POS; Back Office; Browsing; Telemetry Telephony Public: Public Call Offices, small businesses, farmers, private lines Corporate: Telephony/Data infrastructure Internet (IP) High-speed, always-on, Internet-access for consumers, small businesses and schools Intranet and IP infrastructure for the enterprise IP multicast-based services BTV Content delivery 11

Characteristics of GEO Satellites 35, 680 Km above the Earth ~24 Hour Period Average 14 -17 Year Lifespan Single Satellite theoretically can provide up to 42% Earth Coverage Large, expensive, difficult to launch o Located approximately every 2 above the equator Several Satellites may operate at the same azimuth on different frequencies/polarization 12

The Clarke Belt xx 13

GEO/LEO Comparison 14

Geosynchronous Orbit Fleet 15

LEO Orbit Constellation Globalstar Loral initiative Subsidiary of Airtouch (Cellular) Aimed at global cellular phone coverage Qualcomm based CDMA 48 satellite constellation (8 planes x 6 ea. + 4 spares) 52 now in orbit ! 8 orbital planes of 6 satellites each 80% Earth coverage (+/- 68 degrees) LEO orbit (1414 km) Ground Operations Control Centers (GOCCs) and Satellite Operations Control Centers (SOCCs) control gateway and control functions Qualcomm GSP 1600 16

Obtaining Satellite Details http: //www. lyngsat. com 17

Obtaining Satellite Details http: //www. lyngsat. com 18

Satellite Details – Amos 1 http: //www. spacecom. co. il/ Middle East Beam 19

Satellite Details – Amos 1 http: //www. spacecom. co. il/ European Beam 20

VSAT Network Architectures One Way One-Way – Receive Only High Bit-Rate DVB Compliant Outbound Inbound Return Channel via Dial-Up Modem Can be used with existing infrastructure Example: Harmonic’s Cyber. Stream. TM Baseband Equipment Satellite DVB Modulator LAN DVB Receiver RFT IP Encapsulator VSAT TVRO Antenna TCP/IP ACK’s NACK’s Router Internet Modem/ISDN Return 21

VSAT Network Architectures Two-Way Star Topology All VSATs Communicate via a Single Hub Network is Independent of Existing Infrastructure VSAT Antenna Size dependent upon Power and Gain of Hub Antenna Also Upon Inbound Bitrate, ODU Power and Satellite Footprint Contention Based Access – Usually TDMA or FTDMA Typical Ping Times Approximately 650 -700 ms VSAT Hub VSAT VSAT 22

VSAT Network Architectures Two-Way Star Topology – Double Hop 23

VSAT Network Architectures Two-Way Mesh Topology VSATs communicate directly with each other Some systems require initial signaling via the Hub Larger Antennas, Higher Power required at the VSAT Smaller Antenna, Lower Power required at the Hub Used extensively in Telephony Networks Delay minimized on VSAT to VSAT Calls VSAT VSAT 24

Network Components Skystar 360 E 25

Typical Hub Configuration 26

Network Management Entire Network Controlled, Configured and Monitored from a Single Location called the NOC (Network Operations Center) 27

Typical VSAT Indoor Unit (Skystar 360 E) (Front) (Rear) 28

Typical VSAT Outdoor Unit/Antenna Reflector Feed-Assembly LNB-F (Optional) LNB SSPA (HPC) (Front) (Rear) 29

VSAT Communication Bands VSAT Networks use Geostationary Satellites (GEO) All located directly above the equator, at an altitude of ~36, 000 km and spaced approximately every 2 degrees Band Up-Link (GHz) Down-Link (GHz) Notes L . 9 -1. 6 Shared with terrestrial S 1. 610 -1. 625 2. 483 -2. 5 Shared with ISM Band C 3. 7 -4. 2 5. 925 -6. 425 Shared with terrestrial Ku 11. 7 -12. 2 14 -14. 5 Attenuation due to rain Ka 17. 7 -21. 7 27. 5 -30. 5 High Equipment cost; attenuation due to rain 30

Space Segment VSAT Networks lease space segment from the Fixed Satellite Service (FSS) Provider Price is mainly determined by Bandwidth and Power Geosynchronous Satellites frequencies consist of an Uplink and Dowlink, each covering a 500 MHz bandwidth The many transponders operating within this range typically extend from 36 -72 MHz each Each Transponder has a finite power level that is shared amongst the users Excessive Power levels can cause distortion to all users on the transponder 31

Bit Rate/Symbol Rate = Bit Rate # of bits transmitted with each symbol If more bits can be sent with each symbol, then the same amount of data can be sent in a narrower spectrum For example, for a bitstream of 80 kbps using BPSK (1 bit per symbol), the symbol rate is the same. For QPSK (2 bits per symbols), the symbol rate is ½ the bit rate or, 40 kbps. For 8 PSK (3 bits per symbol) is would be 1/3 the bit rate, or 26. 66 kbps 32

Modulation Types Q 0 State 315 o 00 “ 01” 315 deg State 1 State I Q 45 o 11 State 45 deg “ 00” I 135 o 10 State 135 deg “ 10” 225 o 00 “ 11” 225 deg State Q I BPSK – Binary Phase Shift Keying Use alternative sine wave phase to encode bits Simple to implement Inefficient use of Bandwidth Very Robust One bit per symbol (2 States) QPSK – Quadrature (Quarternary) Phase Shift Keying Efficient use of Bandwidth Requires more complex receiver for demodulation Two bits per symbol (4 States) MSK – Minimal Shift Keying Easy to Generate – More Complex Receiver Special form of FSK Spectrally efficient, better noise performance at receiver 33

Forward Error Correction (FEC) FEC provides the ability for transmitted data to be ‘self-correcting’ without the need for re-transmission (As in ARQ) Thus, we can transmit with LESS POWER - The price is Overhead and Bandwidth ! FEC ½ means that for every bit sent, an additional bit of overhead is sent; ¾ means for every 3 bits, one bit of overhead, and so on… BER 10 E-1 Un coded 10 E-2 Coded 10 E-3 10 E-4 10 E-5 Coding 10 E-6 Gain 3 4 5 6 7 8 9 Eb/N 0 35

Forward Error Correction (FEC) Two classes of Forward Error Correction codes Convolutional Codes and Block Codes Convolutional Coding (Viterbi Decoding) Based on minimum hamming distance “code words” feed through a shift register Reed Solomon Code (RS) is a form of Block Code that breaks the data stream up into fixed size blocks and adds redundancy symbols On the other side of the link, the data is decoded using linear algebraic algorithms. This type of code adds considerable overhead Concatenated Viterbi – refers to an error correction technique which uses Viterbi in conjunction with Reed Solomon coding. Adds approximately 2 d. B to the link budget Turbo Codes with an even stronger coding gain will eventually replace Convolutional and RS coding 36

Bit Error Rate (BER) & Eb/N 0 Bit error rate is Directly Proportional to the Eb/N 0 Threshold Typical BER in some VSAT Systems can be <1. 00 E -08 (Less than one error in every 100, 000 bits) for an Eb/No of only 4. 8 d. B “Robust” in the digital worlds describes a system that can be (near) error-free in a noisy signal path C Place Picture of C/N Here Place MSK Signal Here N CW DPSK Modulation 37

Link Budget (Margin( The process of correctly sizing uplink and downlink paths for: Satellite Hub Remotes Takes into account: Satellite performance Path Loss Atmospheric effects Frequency bands Uplink antenna and amplifier performance Download antenna size and receiver noise figure Path Loss at 12 GHz over 36, 000 km can exceed – 205 d. B ! 40

Access Schemes The Need for Bandwidth Efficiency Bandwidth (and power) = $ Better bandwidth efficiency translates into Cost Savings Outbound and Inbound BW proportional to: Number of Users Bit Rate Power/Modulation & Error Correction Coding Type of traffic Qo. S (Quality of Service) Outbound Transmission: Constant, Single Frequency Inbound Transmission: Bursty, Frequency Hopping All VSATs must share the allocated inbound BW OB IB F 1 F 2 F 3 F 4 F 5 F 6 F 7 Fn 41

Access Schemes Time Division Multiple Access (TDMA) Frequency 1 17 11 19 Time Transmissions occur on the same frequency from multiple sources When a collision occurs, each source waits a random amount of time before retransmitting Time slots are allowed to pass unused In a loaded network, more collisions will occur, increasing the random wait time 12 11 17 18 17 Collision Occurs Collision Recognized 11 Retransmits after 3 slots delay time 17 Retransmits after 5 slots delay time 42

Access Schemes Time Division Multiple Access (TDMA) Frequency 1 17 11 19 Time Transmissions occur on the same frequency from multiple sources When a collision occurs, each source waits a random amount of time before retransmitting Time slots are allowed to pass unused In a loaded network, more collisions will occur, increasing the random wait time 12 11 17 18 17 Collision Occurs Collision Recognized 11 Retransmits after 3 slots delay time 17 Retransmits after 5 slots delay time 43

Access Schemes Frequency/Time Division Multiple Access – Random Access (RA) Allocated Bandwidth Inbound Frequencies 1. 2 MHz F 1 120 k. Hz F 2 F 3 102 Time Slots F 4 F 5 F 6 F 7 053 021 006 F 8 F 9 Frequency 006 053 102 021 006 102 F 10 Collision Retransmission 006 Time VSAT 006 VSAT 021 VSAT 053 VSAT 102 44

Access Schemes Automatic Dedicated Access A “private” frequency is allocated to a single VSAT Collision free, high throughput channel for batch applications and file transfer When a DA is required by a VSAT, initiate request is sent in RA mode, triggered According to IP-socket or IP address According X. 25 destination address Throughput based t Then, a DA frequency is allocated RA 34 11 31 f DA DA 17 14 17 21 17 34 17 34 21 14 25 25 14 45

Access Schemes Automatic Partial Dedicated Access Partial allocation for better utilization of DA channel Optimal for Constant Bit Rate (CBR) applications, such as voice Guarantees fixed response time DA can be flexibly divide into PDAs f RA 11 31 17 15 14 17 32 21 17 21 14 17 25 15 17 32 17 25 17 15 17 t 14 32 46

Access Schemes Dual Bit Rate Support of dual bit rate improves space segments utilization Any 2 bit rates can be supported Each VSAT supports two bit rates with multiple access modes Lower bit rate for RA and higher bit rate for DA Each Receiver Cage at the hub can handle two bit rates RA DA 17 f PDA 15 14 17 32 21 17 11 21 t 32 36 17 15 17 76. 8 15 17 14 17 17 25 14 32 153. 6 76. 8 47

Acknowledgments over Satellite Spoofing The Problem: TCP/IP requires acknowledgment of each and every packet The Satellite delay [(36, 000/300000)2]2 in addition to all the routers along the way adds significant latency Spoofing Concept: Acknowledge TCP packets locally at the VSAT/Hub – Send ‘Acknowledge Summary’ periodically No Spoofing With Spoofing 48

Acknowledgments over Satellite Internet Page Acceleration (IPA) On Terrestrial Based Networks, each HTML object is requested and acknowledged IPA requests all the objects on a specific URL All objects on an HTML Page are sent to the VSATs at once 49

Amateur Radio Applications Internet-to-Radio Link Typical Node VSAT Antenna PC + Sound Card + Vo. IP Application VHF or UHF Omni VSAT Radio/PC Interface VHF/UHF Conventional or Trunked Repeater 51

Amateur Radio Applications Internet-to-Radio Link New York Repeater/VSAT Hub Vo. IP Servers Boston Repeater/VSAT Vo. IP Internet Direct Internet London Repeater/Direct 52

Amateur Radio Applications Internet-to-Radio Link - e. QSO xx 53

Amateur Radio Applications Internet-to-Radio Link - Echolink 54

Amateur Radio Applications HF Remote Base/Diversity Reception 55

FAQs (1( What are the Largest VSAT Networks in the World ? Starband ~44, 000 (US ISP); US Postal Service ~33, 000 How many VSATs are operation World-Wide ? >400 K installed by Gilat alone Can a Star VSAT communicate with another VSAT without a Hub ? Star Topology – No. Mesh Topology VSATs can operate Point-to-Point. Can a VSAT work Mobile ? No, due to the associated delay is some systems and antenna pointing issues. Mobile systems are under development. Can a VSAT be used anywhere ? No. It can not be used at the extreme North and South latitudes due to coverage of Geostationary satellites. You must have line-of-site coverage towards the satellite your network is working on. What are typical upsteam and downsteam speeds that can be achieved with a VSAT ? Depends on the VSAT ISP. Btopenworld in the UK is offering 500/120 kbps (Upstream/Downstream) service. Theoretically, much higher speeds can be achieved. 56

FAQs (2( Can I view DVB-S video stream from the same antenna/LNB ? Yes. (So long as it is on the same satellite). Elliptical antennas allow adding two additional LNBs with switchable polarization. How many PC’s can I connect to a VSAT ? Theoretically, as many as you want. The limiting factor is that they will be sharing the Inbound/Outbound Bandwidths. The other limiting factor is the total number of TCP/IP sockets and whether or not the VSAT ISP set up the VSATs to assign an IP address to connected PC. Up to 4 is recommended. What applications are NOT suitable for VSATs ? VSAT traffic has an inherent latency due to the distance. Real-Time Internet Gamming other time-critical applications will not work as well as terrestrial lines. What changes can we expect to see in the future concerning VSAT technology, markets ? When Ka-Band Satellite service begins, we can expect to see much smaller dishes. 8 PSK instead of the current QPSK on the Outbound, Internal Caching on VSAT, plus much more. The Rural Telephony market is booming and when mobile VSAT equipment becomes available, the industry is expected to change entirely. 57

Probing Further… Gilat Satellite Networks Spacenet (Gilat Subsidiary in US) FAQ’s (Btopenworld Satellite Service) Lyngsat (Geostationary Satellite Database) Phase Modulation Tutorials Digital Modulation Basics MPEG Tutorial DVB Standards Tutorial FEC Tutorial Spectrum Analysis Basics Spectrum Analysis AM-FM Measurements www. satil. com (Israeli TVRO Information in Hebrew) AFRTS TVRO Satellite Handbook Channel Master VSAT Antennas Telecommutations Glossary 58