Transcript Marlon K. Schafer (509) 982-2181 Michael Anderson (630)859-1987 A full day primer on the design, construction, and operation of a Wireless ISP. Mike Anderson & Marlon Schafer 11/5/2015

Marlon K. Schafer (509) 982-2181
Michael Anderson (630)859-1987
A full day primer on
the design,
construction, and
operation of a
Wireless ISP.
Mike Anderson & Marlon Schafer
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11/5/2015
WISP = Wireless Internet Service Provider
 In this course you are going to learn the
starting points and basics of becoming an
profitable WISP.
 We are going to assume you know nothing.
If you have a question that we are not
answering, please ask it.
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License Free Bands
Types of Unlicensed Radios
Basic system design
Definitions
Base Station (WPOP) Systems
Customer Premises Equipment (CPE)
Antennas
Calculations
Business plan
System design
Site Survey
Interference Issues
System examples
Cable Building/Connector sealing
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1 MHz = 1,000,000 Hz
1 GHz = 1,000 MHz
1 GHz = 1,000,000,000 Hz
IE:
2400 MHz is the same as 2.4 GHz
928 MHz is the same as 928 MHz
5.8 GHz is the same as 5800 GHz
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Hz = Radio Spectrum
Bits = Data
K= 1,000
M = 1,000,000
G = 1,000,000,000
IE:
83.3 MHz is the amount of spectrum available in the 2.4
GHz band
11 MB/s is the over the air data rate of 802.11b (wi-fi)
radios
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ISM
ISM: Industrial, Scientific, and Medical
UNI-I (or UNII)
Unlicensed National Information Infrastructure
http://www.access.gpo.gov/nara/cfr/waisidx_01/47cfr15_01.html
ISM = http://frwebgate.access.gpo.gov/cgi-bin/get-cfr.cgi?TITLE=47&PART=15&SECTION=247&YEAR=2001&TYPE=TEXT
http://www.access.gpo.gov/nara/cfr/waisidx_01/47cfr18_01.html
902 to 928 MHz
2,400 to 2,483.5 MHz
5,725 to 5,850 HHz
UNII =
http://frwebgate.access.gpo.gov/cgi-bin/get-cfr.cgi?TITLE=47&PART=15&SECTION=407&YEAR=2001&TYPE=TEXT
5,150 to 5,250 MHz
5,250 to 5,350 MHz
5,725 to 5,825 MHz
For some more info go to:
http://www.odessaoffice.com/wireless/power_levels.html
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902 to 928 MHz
 Data rates up to 3 megs
 Non line of sight
 Mostly abandoned but making a comeback
 Unaffected by weather
 Only a few manufacturers of gear
 Expensive compared to 802.11b gear
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2,400 to 2,483.5 MHz
 83.5 MHz of spectrum
 FHSS and DSSS
 Speeds up to 22 Mbps common
 Cheap Equipment
 Not affected by weather
 Needs Line of Sight
 Unlicensed in Most Countries
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5,150 to 5,350/5,725 – 5,825/5,725-5,850(ISM)
Complicated power rules
Gobs of spectrum
Speeds up to 480 Mbps
Speeds up to 54 Mbps becoming common
Less congested than 2.4 GHz in most areas
Migrating from backhaul to distribution
Expensive gear
Mostly proprietary gear
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Two ways are common to all radios
Half duplex
– Uses the same frequency to send and rec.
– Uses different time slots
– Commonly called TDD (time division duplexing)
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Full duplex
– Uses different frequencies to send and rec.
– Uses the same time slots
– Commonly called FDD (frequency division
duplexing)
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http://www.odessaoffice.com/wireless/definitions.htm
There is not enough time to go through them all.
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LOS: Line of sight
NLOS: Near/non LOS
BWA: broadband wireless access
PtMP: point-to-multipoint
PtP: Point-to-point
CPE: customer premises equipment
AP: access point
AU: access unit (same as above)
DS (or DSSS): direct sequence spread spectrum
FH (or FHSS): frequency hopping spread spectrum
RSSI: receive(r) signal strength index/indication
TDD: time division duplex
FDD: frequency division duplex
TDMA: time division multiple access
CSMA/CA: carrier sense multiple access/collision avoidance
CDMA: code division multiple access
ESSID: extended service set ID
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dB: The dB convention is an abbreviation for decibels. It is a mathematical expression showing the
relationship between two values.
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RF Power Level: RF power level at either transmitter output or receiver input is expressed in
Watts. It can also be expressed in dBm. The relation between dBm and Watts can be expressed as
follows: PdBm = 10 x Log Pmw. For example: 1 Watt = 1000 mW; PdBm = 10 x Log 1000 = 30
dBm 100 mW;
PdBm = 10 x Log 100 = 20 dBm. For link budget calculations, the dBm convention is more
convenient than the Watts convention.
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Attenuation: Loss of power, expressed in dB. Attenuation is expressed in dB as follows:PdB = 10 x
Log (Pout/Pin). For example: If, due to attenuation, half the power is lost (Pout/Pin = 2),
attenuation in dB is 10 x Log (2) = 3dB.
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Path Loss: Path loss is the loss of power of an RF signal travelling (propagating) through space. It
is expressed in dB. Path loss depends on: 1. The distance between transmitting and receiving
antennas. 2. Line of sight clearance between the receiving and transmitting antennas. 3. Antenna
height.
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Free Space Loss: Attenuation of the electromagnetic wave while propagating through space. This
attenuation is calculated using the following formula: Free space loss = 32.4 + 20xLog F(MHz) +
20xLog R(Km) F is the RF frequency expressed in MHz. R is the distance between the
transmitting and receiving antennas. At 2.4 Ghz, this formula is: 100+20xLog R(Km).
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No amp
– Add radio output
– Subtract cable/connector losses
– Add antenna gain
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With amp
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Add radio output
Subtract cable/connector losses
Add amp gain
Subtract coax loss
Add antenna gain
For AGC amps use amp output instead of radio output and don’t
count cable/connector loss
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17.5 dB radio – 1 dB misc. connectors – 2.3 dB coax loss +
24 dB antenna gain = 38.2 dB EIRP
30’ LMR 400
coax
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27 dB amp + 8 dB omni = 35 dB
In this case, the amp has AGC (automatic
gain control) so the radio output is not
counted.
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Also known as Path Loss
Amount of signal lost between the two ends of an
RF link.
Calculated with the formula:
Free space loss = 32.4 + 20xLog F(MHz) + 20xLog
R(Km) F is the RF frequency expressed in MHz. R is
the distance between the transmitting and receiving
antennas.
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At 2.4 Ghz, this formula is: 100+20xLog R(Km).
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Coverage is affected by a combination of EIRP and receiver
sensitivity
Add 3 dB and you DOUBLE your wattage
Every 6 dB doubles or halves your coverage range
36 dB cell
4 x more area
30 dB cell
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Notice how there are actually only 3 out of 11
channels that don’t significantly interfere with each
other.
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DSSS from a WiLan radio used for a video
surveillance system shown on a spectrum analyzer.
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802.11 - 2 Mbps - 2.4 GHz
– DSSS
– FHSS
– Infrared
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802.11b - 11 Mbps - 2.4 GHz
– DSSS
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802.11a - 54 Mbps - UNII
– OFDM
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802.11g - 11 and 54 Mbps - 2.4 GHz
– DSSS
– OFDM
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There are several others but there’s no product for them
at this time
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Antennas are also called “Intentional
Radiators” by the FCC
 Antennas focus energy
 Focusing the energy causes a rise in energy
in one direction equal to the loss of it in
another. This is called “Gain”
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Antenna gain is measured at the highest spot on
the coverage pattern
Beamwidth is measured at the point that the
signal drops off by 3 dB
XPol (cross polarization) indicates how well an
antenna isolates signals in the wrong polarization
F/B (front to back) ratio is an indication of how
well an antenna squelches out signal coming in
from behind it’s self
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When an antenna
focuses it’s energy
into a pattern it
develops a
“Beamwidth”
This would be an
approximate
pattern for a
highish gain dish
type antenna
Notice the large
side lobes
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Here is a better
picture of main beam
vs. side lobes
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This is how antenna
patterns are normally
drawn
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Sample of a vertical
pattern for a high
gain (15 dB) omni
This is NOT the kind
of coverage you will
usually want
Notice how much
more signal actually
goes UP into lala
land
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Not all antennas are
created equal
Notice the much
cleaner pattern from
the panel antenna
(bottom) vs. the grid
antenna (top)
Pay special attention
to the amount of
signal that goes out
the BACK of the grid
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All antennas on this
tower are in use
It’s in South America
The 24 dB grids are
all running P-Com
back haul radios. As
I recall there are 20+
of them!
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Design your system with NO amps as much as possible.
Don’t use amps at customer installs
Amps go at the antenna
For most amps try to keep coax loss down below 6 to 10 dB between the radio and the amp
Don’t over amp, as a rule the FCC HATES amps
There are basically two different types of amps:
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AGC (automatic gain control)
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Constant output
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Gives the same boost to the signal at all times
Less complicated and sometimes less expensive
All amps add noise to the system
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Adjusts it’s output as needed to give a set dB total output
Generally easier to deploy as cable loss isn’t as much of an issue
Usually about 3 dB
Amps do NOT add coverage to a system, power does that
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Bigger amps do not always mean that a system will go further
For ptmp systems you are generally allowed 36 dB (4 watts)
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A 9 dB omni with a 500mW (27 dB) will go NO further than a 12 dB omni with a 250 mW (24 dB) amp
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Pronounced Frunel
The area around a LASER beam tight radio
link, a buffer zone if you will
Cigar shaped
Is all they way around an RF link but usually
thought of as being on the bottom of it
Anything that’s in the RF path’s buffer zone is
considered to be in the Fresnel Zone
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Receive signal Level
– RSL=Tx Power-Tx cable loss+Tx andtenna gainFSL+RX antenna gain-Rx cable loss
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Free Space Loss
– FSL = 20Log10(MHz)+20Log10(distance in
miles)+36.6
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SOM (system operating margin)
– SOM=Rx signal level-Rx sensitivity
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milliWatt to dBm
– dBm=(10Log10(mW))
– 1 mW=0dBm
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dBm to Watt
– Watts=10((dBm-30)/10)
– mW=10(dBm/10)
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Realistic customer base in 12 to 18 months
– Assume 20% of the population split among all broadband
providers
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What kind of customers do you want
How many live/work within your expected coverage
What kind of service will you give
What will they be willing to pay
What kind of equipment will your service require
How many wpops will you need to cover them
– Both from an RF and from a BW stanpoint
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Local paper
Billboards
Radio
TV
Door to door
Word of mouth
Flyers at local businesses
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Choosing a site
– Look before you leap
– First do a visual sweep of
the area
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Can you see your customer
base well?
Is there a better spot?
Are there others already up
there?
Are there any other
systems up there?
Mike Anderson & Marlon Schafer
This system is in Greece. The customer’s
antennas are the two grids. He has to amp them
to go 15 miles due to all of the noise in the area.
He’d have been better off to use solid dish
antennas, or better yet a different local.
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Look for causes of
interference.
– It could be your own
– It could be from someone
else
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One of this person’s other
towers was on a cell phone
tower. It looked even
worse than this.
Mike Anderson & Marlon Schafer
The red arrow is showing a DSSS backhaul,
blue is ONE of the dead areas of the FHSS
distribution system caused by another DSSS
backhaul link on the same tower.
Notice how little of the system is actually
working. If this were a correctly designed and
installed wpop the FHSS system would have
filled in pretty evenly all the way across the
display.
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Make sure that there are no
high end radio systems in
the same frequency range
as you
– This was from a Western
Multiplex Lynx FDD
system. Transmits one
direction on one frequency
and the other direction on
another frequency
– Very nice system
– Unless it’s not yours…..
Mike Anderson & Marlon Schafer
The Blue arrow is from a 30 mile cell phone
tower link. It’s 1 mile away and ¼ mile to the
side of my site.
The orange arrow is from the OTHER and of
that link, 30 miles away.
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Try to locate your
system where no one
else is
Look for places that
can see the most
(notice that I didn’t say
all) potential
customers
The arrow points to the NOC where the wireless
backhaul is located.
This is the view of downtown Odessa as seen
from the 200’ hill where my main broadcast
antenna is.
Mike Anderson & Marlon Schafer
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The antenna is 20’ higher, on the peak of
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Herman’s second story roof.
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This would
be a typical
small WPOP
broadcast
setup
You can see
the radio,
pigail, dc
injector,
amp, coax,
antenna and
a mount for
the side of a
building/pole
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www.isp-lists.com
www.wispcon.info
www.part-15.org
www.wcai.com
www.fcc.gov
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