1. Line-of-Sight IP Networks Johnathan Poarch Senior Information Tech Specialist

2. Line-of-Sight (LoS) History Early LoS systems developed by US military in the 1940s. Extensive TeleCom use in 1950s and 1960s for LD and TV (AT&T Long Lines System) Modern use by TV relay and backbone carriers for cellular systems

3. Use of LoS in IT Intra-campus IP/VoIP/CCTV (fiber replacement) Site-to-Site connectivity Temporary or backup connectivity to WAN/Internet

4. Typical LoS Topologies Point-to-Point Point-to-Multipoint Mesh

5. LoS Planning Considerations Affected greatly by environmental constraints, including rain fade Very limited penetration capabilities through obstacles such as hills, buildings and trees Sensitive to high pollen count Signals can be degraded during Solar events

6. Common Types of LoS Systems Microwave Directional (long range) WiFi Laser Leased systems

7. Microwave LoS Most common for short range data “back hauls” Licensed Bands – Higher frequency and power Unlicensed Bands – Lower initial cost; plug and play (solutions start under $5,000)

8. Directional WiFI High signal noise in 2.4GHz band Commercial 802.11 radios can be used with directional antennas Amplifiers can also be used to extend range

9. Laser LoS Secure data transmission Up to 1Gbps throughput 200m to 5km range Solutions start under $10,000

10. Leased Systems More common in metropolitan areas Monthly service fee with little/no customer intervention Typically much larger (shared) bandwidth available Can become saturated during large scale outages that impacts multiple customers

12. Discussion Topics Security of LoS solutions Protection of LoS systems Tower/roof rights Use of relaying

13. Security of LoS solutions Most LoS is considered “private network” and difficult to remotely compromise Very susceptible to physical compromise Beware of shared/co-used transmission sites (roof tops, shared towers, ect)

14. Protection of LoS Systems Environmental and weather conditions can have heavy impact on reliability Monitoring systems are critical

15. Tower and Roof Rights Any tower/roof rights should be secured in writing Seaming LoS obstacles may be best transmission sites Backup connectivity can often be shared among tenants in order to secure rights and lower cost

16. LoS Relaying LoS relaying is often used to extend range and circumvent obstacles Increased points of failure