Using Mikrotik For NLOS Neighborhood.pdf

(c) LearnMikrotik.com, 2009

Case Study: Using MikroTik for Non-Line of Sight Neighborhood Cells


About Me

• Steve Discher• College Station, Texas USA




About Me

• Operate a WISP with about 350 subscribers, sales for a 17,000 sq-ft Tier IV Data Center (FIBERTOWN.com)

• Supply bandwidth to another WISP with about 1,200 subscribers

• MikroTik Instructor, consultant, LearnMikroTik.com


The Problem

• Conventional unlicensed 802.11a/b/g technologies in the 2.4-5.8 spectrum require line of sight between the client and the access point for reliable links

• Exceptions• In many areas, 50-60 foot structures are

required to establish line of sight from customer locations to clear tree canopy


The Problem

Options: • Telescoping masts• Bracketed towers• Guyed towers• Free standing towers• Available structure



Telescoping Masts

• Expensive / labor intensive to erect• Unsightly• Expensive to maintain• May be prohibited by homeowner’s associations• Incremental cost any time the equipment needs

servicing, often damaged or turned in windy conditions

• Average cost for a 50 foot telescoping mast installed - $300 US ($50-75 labor each time serviced)


Bracketed, Guyed, Free Standing Towers

• Expensive / labor intensive to erect• Unsightly• Homeowners concerned about lightning• May be prohibited by homeowner’s

associations• Average cost for a 50 foot Rohn tower,

installed - $1,500 US


A Solution

• Non-line of sight equipment operating in the 900 MHz spectrum

• Lower frequencies have the ability to “cut through” some amounts of foliage thereby allowing you to mount the device below the tree canopy


New Solution – New Advantages

• 900 MHz frequency penetrates foliage BETTER than 2.4 or 5.8 GHz

• WILL NOT penetrate hills or mountains• WILL NOT penetrate miles of foliage• New sources of interference

Remember: “Most problems are the result of a previous solution.”


Legacy Frequency Wi-Fi Solutions

• 2.4 GHz suffers from interference from:o Cordless phoneso Wireless home routerso Baby monitorso Other ISP’s


New Solution-New Challenges

• 900 MHz suffers from interference from:o Cordless phoneso Baby monitorso Other ISP’s (especially Motorola Canopy)o SCADA – Supervisory Control and Data

Acquisition systems, utility companies, oilfield service companies, etc.

o Paging companies


Adapting the New Solution

• Mistake #1: “I can simply add a 900 AP next to my existing 2.4 and 5.8 AP’s on my 300 foot tower and serve all the customers I previously turned down.”

• If you thought 2.4 had interference issues, wait until you try 900!



• Mitigate interference from external sources

• Mitigate interference from internal sources




• Mitigate interference from external sources

• Mitigate interference from internal sources• Maintain low cost of entry for customers• Operate in areas where homeowner’s

restrictions may prevent the use of towers or masts


What are neighborhood cells?


Neighborhood Cells

• Utilize conventional, existing towers and unlicensed/licensed links to backhaul bandwidth into neighborhoods

• Utilize NLOS frequencies for access within the neighborhood


Neighborhood Cells

• This design tracks the Three-Layered Hierarchical Modelo Core Layero Distribution Layero Access Layer

• Benefit of utilizing existing Wi-Fi infrastructure as your Distribution Layer

• New, low cost infrastructure as the Access Layer



The Equipment

• Distribution Layero Existing P-MP Wi-Fi gear, typically 5.x GHz for

higher throughput and decreased interference due to more available channels

o Our network, all MikroTik and Nstremeo AP’s (access points) located on water towers,

backhauled to our core in the Data Center


The Equipment

• Access Layer (neighborhood Tower & CPE)o Ubiquity 900 MHz cards with MikroTik for APo Omni antenna at APo Integrated panel antennas with Ubiquity 900

MHz cards with MikroTik for CPE



+ +

Neighborhood Tower - Access

RouterBoard 433

Comet 9.2 dBi Omin


+ +

Neighborhood Tower - Distribution

RouterBoard 433AH(Dual Cards)

Arc Wireless 23 dBiPanel


+ +

CPE – Customer Premise Equipment

RouterBoard 411

ArcWireless 12.5 db Integrated


The Neighborhood Tower Itself

• Most Cost Effective – existing Rohn TV towero Lowest cost of entryo Trade space on tower for serviceo Fastest deploymento May have been “grandfathered” into the

subdivision thereby avoiding issues with restrictions or covenants


The Neighborhood Tower Itself

• Least Cost Effective – build a bracketed or free standing towero Higher cost of entryo Trade ground lease for tower for serviceo Longer deployment timeo Better choice of location


Final Configuration


Examples


Examples


Examples

Remote Reboot

UPS

POE

Customer POE

NEMA Enclosure


Interference Mitigation

• Use top of tower to shoot over canopy for backhaul, 50-60 ft level

• Place the 900 omni at or just below treetop level to shield it from external interference

• Provides shortest length of shot through foliage


Interference Mitigation


The Economics

• ROI – Faster return on Investment, conventional large scale, point-to-multipoint towers versus neighborhood cells


Conventional Distribution Tower Model

• Typically employ at least 3 access points on 120 degree sectors to serve 360 degree area

• Depending on the technology used, rates delivered and other factors, each AP can server 40-50 clients

• Total client load per tower, 150 clients• Each client requires line of sight• Based on our experience, in our area somewhere

between 35% and 60% of clients that we could serve require a tower to clear tree canopy


Capital Investment - Tower

• Assuming typical construction costs for a 200 foot tower with 3 each 5 GHz Ap’so Tower, labor and materials: $10,000o Sector Antennas: $200 ea = $600o Radios: $250 ea = $750 o Backhaul: Antennas and electronics $900o Switch, POE’s, labor, misc $600 Total capital investment for tower $12,850 Average cost per client at 75% of full capacity $114


Capital Investment Neighborhood Cell

• Best case scenario, customer with existing TV towero Install electrical, labor and materials: $200o AP/BH Radio: $350o 900 Omni $85o 5.8 Backhaul antenna $85o Switch, POE’s, labor, misc $400 Total capital investment for tower $1,120 Average cost per client at 75% of full capacity (15

clients typical) $74


Other Considerations

• Higher rate of penetration into a market area due to:o reduced up-front costo reduced footprint at CPE, aestheticso ability to operate in areas with homeowner’s

restrictions that may prevent owning a towero faster time to market


Summary of Costs per Client

• Conventional Towero Total investment $12,850o $114 per Client

• Neighborhood Cell:o Total investment $1,120o $74 per client

Note: CPE cost is higher for 900 but typically this is covered by the installation fee.


15 clients associated, lowest signal strength -85


Summary

• NLOS Neighborhood cells can provide:• Penetration into areas where service was

previously not possible• Lower cost of entry• Lower build-out cost per client• Faster time to market• Interference mitigation• Faster return of capital investment


Contact Me

Steve Discher Certified MikroTik Trainer & Consultant

[email protected] http://www.LearnMikrotik.com

Documents

Using Mikrotik For NLOS Neighborhood.pdf