marlon k. schafer (509) 982-2181 michael anderson (630)859-1987
DESCRIPTION
WISP Basics. 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. Introduction. WISP = Wireless Internet Service Provider - PowerPoint PPT PresentationTRANSCRIPT
04/19/23Mike Anderson & Marlon Schafer1
Marlon K. Schafer (509) 982-2181Marlon K. Schafer (509) 982-2181Michael Anderson (630)859-1987Michael Anderson (630)859-1987
A full day primer on A full day primer on the design, the design, construction, and construction, and operation of a operation of a Wireless ISP.Wireless ISP.
04/19/23Mike Anderson & Marlon Schafer2
WISP = Wireless Internet Service ProviderIn 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.
04/19/23Mike Anderson & Marlon Schafer3
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
04/19/23Mike Anderson & Marlon Schafer4
1 MHz = 1,000,000 Hz1 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
04/19/23Mike Anderson & Marlon Schafer5
Hz = Radio SpectrumBits = DataK= 1,000
M = 1,000,000G = 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
04/19/23Mike Anderson & Marlon Schafer6
ISMISM: 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 MHz5,725 to 5,850 HHzUNII = 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 MHz5,250 to 5,350 MHz5,725 to 5,825 MHz
For some more info go to:http://www.odessaoffice.com/wireless/power_levels.html
04/19/23Mike Anderson & Marlon Schafer7
902 to 928 MHzData rates up to 3 megsNon line of sightMostly abandoned but making a comebackUnaffected by weatherOnly a few manufacturers of gearExpensive compared to 802.11b gear
04/19/23Mike Anderson & Marlon Schafer8
2,400 to 2,483.5 MHz83.5 MHz of spectrumFHSS and DSSSSpeeds up to 22 Mbps commonCheap EquipmentNot affected by weatherNeeds Line of SightUnlicensed in Most Countries
04/19/23Mike Anderson & Marlon Schafer9
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
04/19/23Mike Anderson & Marlon Schafer10
Monday, January 20, 2003Wireless layout
Page 1
InternetRouter
Hub
Radio tower
IBM Compatible
IBM Compatible
IBM Compatible
City
Radio tower
04/19/23Mike Anderson & Marlon Schafer11
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)
Full duplex– Uses different frequencies to send and rec.– Uses the same time slots– Commonly called FDD (frequency division
duplexing)
04/19/23Mike Anderson & Marlon Schafer12
http://www.odessaoffice.com/wireless/definitions.htm There is not enough time to go through them all.
– 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
04/19/23Mike Anderson & Marlon Schafer13
dB: The dB convention is an abbreviation for decibels. It is a mathematical expression showing the relationship between two values.
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.
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.
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.
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).
04/19/23Mike Anderson & Marlon Schafer14
No amp– Add radio output– Subtract cable/connector losses– Add antenna gain
With amp– 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
04/19/23Mike Anderson & Marlon Schafer15
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
04/19/23Mike Anderson & Marlon Schafer16
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.
04/19/23Mike Anderson & Marlon Schafer17
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.
At 2.4 Ghz, this formula is: 100+20xLog R(Km).
04/19/23Mike Anderson & Marlon Schafer18
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
30 dB cell
36 dB cell4 x more area
04/19/23Mike Anderson & Marlon Schafer19
Notice how there are actually only 3 out of 11 channels that don’t significantly interfere with each
other.
04/19/23Mike Anderson & Marlon Schafer20
DSSS from a WiLan radio used for a video surveillance system shown on a spectrum analyzer.
04/19/23Mike Anderson & Marlon Schafer21
802.11 - 2 Mbps - 2.4 GHz– DSSS– FHSS– Infrared
802.11b - 11 Mbps - 2.4 GHz– DSSS
802.11a - 54 Mbps - UNII– OFDM
802.11g - 11 and 54 Mbps - 2.4 GHz– DSSS– OFDM
There are several others but there’s no product for them at this time
04/19/23Mike Anderson & Marlon Schafer22
Antennas are also called “Intentional Radiators” by the FCC
Antennas focus energyFocusing the energy causes a rise in
energy in one direction equal to the loss of it in another. This is called “Gain”
04/19/23Mike Anderson & Marlon Schafer23
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
04/19/23Mike Anderson & Marlon Schafer24
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
04/19/23Mike Anderson & Marlon Schafer25
Here is a better picture of main beam vs. side lobes
04/19/23Mike Anderson & Marlon Schafer26
This is how antenna patterns are normally drawn
04/19/23Mike Anderson & Marlon Schafer27
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
04/19/23Mike Anderson & Marlon Schafer28
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
04/19/23Mike Anderson & Marlon Schafer29
04/19/23Mike Anderson & Marlon Schafer30
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!
04/19/23Mike Anderson & Marlon Schafer31
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:
– AGC (automatic gain control) 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
– Constant output Gives the same boost to the signal at all times Less complicated and sometimes less expensive
All amps add noise to the system– Usually about 3 dB
Amps do NOT add coverage to a system, power does that– Bigger amps do not always mean that a system will go further– For ptmp systems you are generally allowed 36 dB (4 watts)
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
04/19/23Mike Anderson & Marlon Schafer32
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
04/19/23Mike Anderson & Marlon Schafer33
Receive signal Level– RSL=Tx Power-Tx cable loss+Tx andtenna gain-
FSL+RX antenna gain-Rx cable loss Free Space Loss
– FSL = 20Log10(MHz)+20Log10(distance in miles)+36.6
SOM (system operating margin)– SOM=Rx signal level-Rx sensitivity
04/19/23Mike Anderson & Marlon Schafer34
milliWatt to dBm– dBm=(10Log10(mW))
– 1 mW=0dBm dBm to Watt
– Watts=10((dBm-30)/10)
– mW=10(dBm/10)
04/19/23Mike Anderson & Marlon Schafer35
Realistic customer base in 12 to 18 months– Assume 20% of the population split among all broadband
providers 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
04/19/23Mike Anderson & Marlon Schafer36
Local paper Billboards Radio TV Door to door Word of mouth Flyers at local businesses
04/19/23Mike Anderson & Marlon Schafer37
Choosing a site– Look before you leap
– First do a visual sweep of the area
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?
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.
04/19/23Mike Anderson & Marlon Schafer38
Look for causes of interference.– It could be your own
– It could be from someone else
One of this person’s other towers was on a cell phone tower. It looked even worse than this.
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.
04/19/23Mike Anderson & Marlon Schafer39
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…..
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.
04/19/23Mike Anderson & Marlon Schafer40
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.
The antenna is 20’ higher, on the peak of Herman’s second story roof.
04/19/23Mike Anderson & Marlon Schafer41
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
04/19/23Mike Anderson & Marlon Schafer42
04/19/23Mike Anderson & Marlon Schafer43
04/19/23Mike Anderson & Marlon Schafer44
04/19/23Mike Anderson & Marlon Schafer45
04/19/23Mike Anderson & Marlon Schafer46
04/19/23Mike Anderson & Marlon Schafer47
04/19/23Mike Anderson & Marlon Schafer48
04/19/23Mike Anderson & Marlon Schafer49
www.isp-lists.com www.wispcon.info www.part-15.org www.wcai.com www.fcc.gov