rf networking

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RF Networks



There are two aspects of networking which must be consideredwhen installing either an NCL or LMS product:

1. Ethernet Networking (IP)

2. Radio Networking (RF)

This presentation will focus on the RF side of the NCL and

LMS products.



RF TerminologyWavelength is the distance between identical points in the

adjacent cycles of a waveform. In wireless systems, this

length is usually specified in meters, centimeters, or

millimeters



The size of the wavelength varies depending on the frequencyof the signal. Generally speaking, the higher the frequency

the smaller the wavelength.

The WaveRider family of products operate in the 2.4000 -

2.4835 GHz range (NCL and LMS2000) as well as the 905 -925 MHz range (LMS3000).

At 2.4 GHz the wavelength is 12.5cm

At 905 MHz the wavelength is 33cm



These values are calculated using the following formula:

Wavelength = 3 x 102

f (frequency in MHz)

This calculation is important to remember, especially when

installing antennas. Ideally, the antenna should be installed no

closer than 10 wavelengths to the nearest reflective surface.



Frequency

Frequency is the number of complete cycles per second in

alternating current direction. The standard unit of frequency is

the hertz, abbreviated Hz. If a current completes one cycle per

second, then the frequency is 1 Hz.

Kilohertz (kHz)

Megahertz (MHz)

Gigahertz (GHz)Terahertz (THz)



Frequency Spectrum

Designation Abbreviation Frequencies Free-space Wavelengths

Very Low Frequency VLF 9 kHz - 30 kHz 33 km - 10 km

Low Frequency LF 30 kHz - 300 kHz 10 km - 1 km

Medium Frequency MF 300 kHz - 3 MHz 1 km - 100 m

High Frequency HF 3 MHz - 30 MHz 100 m - 10 m

Very High Frequency VHF 30 MHz - 300 MHz 10 m - 1 m

Ultra High Frequency UHF 300 MHz - 3 GHz 1 m - 100 mm

Super High Frequency SHF 3 GHz - 30 GHz 100 mm - 10 mm

Extremely High Frequency EHF 30 GHz - 300 GHz 10 mm - 1 mm



Spectrum800 850 900 960

DAMPS 869 894

GSM/NMT 890 915 935 960

EGSM 870 915 925 960

TACS 890 905 935 950

ETACS 872 905 917 950

PDC 940 958

AMPS 824 849 869 894

iDEN 806 821 851 866

ESMR 806 824 851 869

UP-SMR896-

901

940 -

945

NPCS901-

902

930-

931

940 -

941

PAGING 929 932

ISM 902 928

1700 1800 1900 2000 2500

PCN/DCS 1710 1785 1805 1880

PCS 1850 1910 1930 1990

ISM 2400-2483.5



Tx PowerTx is short for “Transmit”

All radios have a certain level or Tx power that the radio

generates at the RF interface. This power is calculated as the

amount of energy given across a defined bandwidth and is

usually measured in one of two units:

1. dBm – a relative power level

referencing 1 milliwatt

2. W – a linear power level

referencing Watts



dBm = 10 x log[Power in Watts / 0.001W]

W = 0.001 x 10

[Power in dBm / 10 dBm]

The NCL and LMS radios have Tx power of +18dBm, which

translates into .064 W or 64 mW.



Rx Sensitivity Rx is short for “Receive”

All radios also have a certain „point of no return‟, where if they

receive a signal less than the stated Rx Sensitivity, the radio

will not be able to „see‟ the data.

This is also stated in dBm or W.

The NCL and LMS radios have a receive sensitivity of – 82 dBm.

At this level, a Bit Error Rate (BER) of 10-5 (99.999%) is seen.

The actual level received at the radio will vary depending on

many factors.



Radiated Power

In a wireless system, antennas are used to convert electricalwaves into electromagnetic waves. The amount of energy theantenna can „boost‟ the sent and received signal by is referred toas the antennas Gain.

Antenna gain is measured in:

1. dBi: relative to an isotropic radiator

2. dBd: relative to a dipole radiator0 dBd = 2.15 dBi



There are certain guidelines set by the FCC that must be met interms of the amount of energy radiated out of an antenna. This

„energy‟ is measured in one of two ways:

1. Effective Isotropic Radiated Power (EIRP)

measured in dBm = power at antenna input [dBm] +

relative antenna gain [dBi]

2. Effective Radiated Power (ERP)

measured in dBm = power at antenna input [dBm] +

relative antenna gain [dBd]



Energy Losses

In all wireless communication systems there are several factors

that contribute to the loss of signal strength. Cabling,

connectors, lightning arrestors can all impact the performance of

your system if not installed properly.

In a „low power‟ system (such as the NCL and LMS products)

every dB you can save is important!! Remember the “3 dB

Rule”.

For every 3 dB gain/loss you will either double your power

(gain) or lose half your power (loss).



-3 dB = 1/2 power

-6 dB = 1/4 power

+3 dB = 2x power

+6 dB = 4x power

Sources of loss in a wireless system: free space,cables, connectors, jumpers, obstructions



FCC Guidelines

The ISM Bands are defined as follows:

902 to 928 MHz

2400 to 2483.5 MHz

5725 to 5850 MHz

FCC Part 15, Class B

Unlicensed operation from 2400 to 2483.5 MHz

P2P - EIRP : +36 dBm (4 Watts)

: 3:1 i.e. +24 dBm into 24 dBi

P2MP - EIRP : +36 dBm (4 Watts)

: 3:1 at subscriber (considered P2P)



System must be installed by a “Professional Installer” as defined in

FCC Document 15.247 Part 15;

Complete understanding of FCC emissions regulations for

unlicensed operation in the 2.4 GHz ISM Band.

Installer must have a full understanding of the impact of various

types of antennae, amplifiers and other active and passive

components on the compliance of the equipment under FCC

regulations.

FCC - Installer



An external Power Amp cannot be used in conjunction with WR

radio components, in order to comply with FCC regulatory

emissions requirements. Use of an external PA device with a

WaveRider system is deemed illegal and may result in significant

penalty to the manufacturer, seller, and customer.

Unique connectors provide means of compliance.

Standard connectors require professional installation to ensure

compliance.

FCC - Installation



WaveRider High Speed

Wireless Systems

The NCL and LMS systems are designed to support terrestrial fixed

links in an outdoor environment. Typical distances achieved while

staying within FCC guidelines are:

Point to Multipoint: up to 8km

Point to Point: up to 15km

These distances may vary depending on the installation, antennae

chosen, cabling, etc.



NCL1155 Spec Sheet



Direct Sequence Spread Spectrum

Also known as Direct Sequence Code Division Multiple Access (DS-

CDMA), DSSS is one of two approaches to spread spectrum

modulation for digital signal transmission over the air.

The stream of information to be transmitted is divided into small

pieces, each of which is allocated to a frequency channel across the

spectrum.

When transmitted, the data is combined with a higher data-rate bitsequence (also known as a chipping code) that divides the data

according to a spreading ratio.



The transmitter and the receiver must be synchronized with thesame spreading code.

The chipping code helps the signal resist interference and also

enables the original data to be recovered if data bits are damaged

during transmission.

22 MHz wide



Frequency Hopping Spread

SpectrumAlso known as Frequency Hopping Code Division Multiple Access

(FH-CDMA), FHSS radios transmit "hops" between available

frequencies according to a specified algorithm which can be either

random or preplanned.

The transmitter operates in synchronization with a receiver, which

remains tuned to the same center frequency as the transmitter.



TIME

1 2 3 4 5 6 7 8 9 10 11 12

f1

f2

f3

f4

f5

Each

channel1MHz wide

Hopset

FHSS – an example



Signal Propagation

As the signal leaves the antenna it propagates, or disperses, into

space. The antenna selection will determine how much

propagation will occur.

At 2.4 GHz it is extremely important to ensure a that a path (ortunnel) between the two antennas is clear of any obstructions.

Should the propagating signal encounter any obstructions in the

path, signal degradation will occur.

Trees, buildings, hydro poles, and towers are common

examples of path obstructions.



The greatest amount of loss in your wireless system will be fromFree Space Propagation. The Free Space Loss is predictable

and given by the formula:

FSL(dB) = 32.45 + 20Log10F(MHz) + 20Log10D(km)

The Free Space Loss at 1km using a 2.4 GHz system is:

FSL(dB) = 32.45 + 20Log10(2400) + 20Log10(1)= 32.45 + 67.6 + 0

= 100.05 dB



Line of Sight

Attaining good Line of Sight (LOS) between the sending and

receiving antenna is essential in both Point to Point and Point to

Multipoint installations.

Generally there are two types of LOS that are used discussed

during installations:

1. Optical LOS - is related to the ability to see one

site from the other

2. Radio LOS – related to the ability of the receiver

to „see‟ the transmitted signal



To quantify Radio Line of Sight, the Fresnel Zone theory is

applied. Think of the Fresnel Zone as a football shaped tunnel

between the two sites which provides a path for the RF signals.

At WaveRider acceptable Radio Line of Sight means that at

least 60% of the first Fresnel Zone plus 3 meters is clear of any

obstructions.



2nd* 1st*3rd*

* Fresnel Zones

Fresnel Zones



Site A

Site B• Fresnel Zone diameter depends upon

Wavelength, and Distances from the sitesalong axis

• For minimum Diffraction Loss, clearance ofat least 0.6F1+ 3m is required

d 2

d 1

Radius of n th Fresnel Zone givenby:

21

21

d d

d d n r

n +

= l

The First Fresnel Zone



When obstructions intrude on the first Fresnel Zone many issuescan arise which will affect the performance of the system. The

main issues are:

1. Reflection

– incident wave propagates away from smooth scattering

plane

– multipath fading is when secondary waves arrive out-of-

phase with the incident wave causing signal degradation



2. Refraction

– incident wave propagates through scattering plane but at an

angle

– frequencies less than 10 GHz are not affected by heavy

rains, snow, “pea-soup” fog

– at 2.4 GHz, attenuation is 0.01 dB/Km for 150mm/hr of

rain

3. Diffraction

– incident wave passes around obstruction into shadowregions



The Path Profile

Path Profile characteristics maychange over time, due to vegetation,building construction, etc.

Path Profile characteristics maychange over time, due to vegetation,building construction, etc.



FiveNines™ V1.2



Antenna - How it Works

The antenna converts radio frequency electrical energy fed to it (via

the transmission line) to an electromagnetic wave propagated into

space.

The physical size of the radiating element is proportional to the

wavelength. The higher the frequency, the smaller the antenna size.

Assuming that the operating frequency in both cases is the same,

the antenna will perform identically in Transmit or Receive mode



The type of system you are installing will help determine the

type of antenna used. Generally speaking, there are two „types‟

of antennae:

1. Directional

- this type of antenna has a narrow beamwidth; with the

power being more directional, greater distances are usually

achieved but area coverage is sacrificed

- Yagi, Panel, Sector and Parabolic antennae

- an EUM, NCL Station/Master will use this type of antenna

in both Point to Point and Point to Multipoint



2. Omni-Directional

- this type of antenna has a wide beamwidth and radiates

3600; with the power being more spread out, shorter

distances are achieved but greater coverage attained

- Omni antenna

- a CCU or an NCL Master will use this type of antenna



Yagi

- better suited for shorter links

- lower dBi gain; usually between 7 and 15 dBi



Typical Radiation Pattern for a Yagi



Parabolic

- used in medium to long links

- gains of 18 to 28 dBi

- most common



Typical Radiation Pattern for a Parabolic



Sectoral

- directional in nature, but can be adjusted anywhere from 450 to

1800

- typical gains vary from 10 to 19 dBi

0

0



90

180

270 0 -3 -6 -10

-15

-20

-30

dB90

180

270 0 -3 -6 -10

-15

-20

-30

dB

Typical Radiation Pattern for a Sector



Omni

- used at the CCU or Master NCL for wide coverage

- typical gains of 3 to 10 dBi



Typical Radiation Pattern for an Omni



Antenna Radiation Patterns

Common parameters

– main lobe (boresight)

– half-power beamwidth (HPBW)

– front-back ratio (F/B)

– pattern nulls

Typically measured in two planes:

• Vector electric field referred to E-field

• Vector magnetic field referred to H-field



An antennas polarization is relative to the E-field of antenna.

– If the E-field is horizontal, than the antenna is Horizontally

Polarized.

– If the E-field is vertical, than the antenna is Vertically Polarized.

Polarization

No matter what polarity you choose, all antennas in the same RF

network must be polarized identically regardless of the antenna

type.



Polarization may deliberately be used to:

– Increase isolation from unwanted signal sources (Cross

Polarization Discrimination (x-pol) typically 25 dB)

– Reduce interference

– Help define a specific coverage area

Horizontal

Vertical



Antenna Impedance

A proper Impedance Match is essential for maximum power

transfer. The antenna must also function as a matching load for

the Transmitter ( 50 ohms).

Voltage Standing Wave Ratio (VSWR), is an indicator of how

well an antenna matches the transmission line that feeds it.

It is the ratio of the forward voltage to the reflected voltage. Thebetter the match, the Lower the VSWR. A value of 1.5:1 over the

frequency band of interest is a practical maximum limit.



Return Loss is related to VSWR, and is a measure of the

signal power reflected by the antenna relative to the forward

power delivered to the antenna.

The higher the value (usually expressed in dB), the better. Afigure of 13.9dB is equivalent to a VSWR of 1.5:1. A Return

Loss of 20dB is considered quite good, and is equivalent to a

VSWR of 1.2:1.



VSWR Return Loss Transmission Loss

1.0:1 0.0 dB

1.2:1 20.83 dB 0.036 dB

1.5:1 13.98 dB 0.177 dB

5.5:1 3.19 dB 2.834 dB

Distance-to-faultC H E R B A 0 4



-5 0

-4 0

-3 0

-2 0

-1 0

0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 5 5 6 0

M 1

C H E R - B - A 0 4

M o d e l: S 3 3 2 B S e r ia l # : 0 0 0 0 4 0 9 6D a te : 0 6 / 2 7 /2 0 0 0 T i m e : 1 2 : 0 3 :5 9

Bia sT e e : O F F O u tp u t P o w e r : - 3 0 .0 0 d B mRe so lu tio n : 2 5 9 C A L : O N ( CO A X ) C W O n

R

e

t u

r n

L

o

s

s

( d

B

)

Dis tance (0 .0 - 60 .0 Fee t )

M1 : -3 . 7 2 8 d B @ 5 0 . 6 9 8 F e e t



Environmental Effects

Ice and wind loading, Salt sprayRadomes used to improve performance in icy, windy

conditions (more common with larger solid parabolic

dishes). Wind loading can be reduced substantially by

using a radome.

Wind loading can produce vibration, which in turn can

produce azimuth errors. For longer paths, this can be critical.

Installation - pay close attention to proper sealing of all

connector junctions.



The Transmission Line

AndrewCorporationHeliax

TimesMicrowaveLMR types

The type of cable selected depends mostly on the length of that

cable required. Generally, the longer the cable run the better

the cable must be in terms of attenuation.

Attenuation refers to the degradation of the signal as it travels

through the cable. This is usually stated as a loss in dB per 100

feet.



Cable Type Attenuation at 2.4 GHz

per 100 feet

RG8 10

LMR400 6.8

Heliax 3/8" 5.36

LMR600 5.4

Heliax 1/2" 3.74Heliax 5/8" 2.15

Attenuation Table



Transmission Line Selection

Physical Characteristics:

Bend radius

Diameter - transition considerations (interface „jumper

cable‟ use)

Environmental considerations

Plenum installation (fire retardant)

Special weather-resistant types

UV resistance very important in tropics



Line Loss or Attenuation paramount – refer to your Link Budget

Calculations to determine how much loss is acceptable and still

have a viable link.

Foam dielectric, Air Dielectric, Pressurized types of Coaxial

Cable. Waveguide use also possible but typically not cost-

effective



Connectors

Your connector selection will be determined based on thefollowing:

- connector gender at antenna

- type of cable being used

- use of lightning protection

- gender of jumpers being used



For the most part the cabling manufacturers also manufacturethe connectors that go on the cables. „Knock off‟ connectors

are available, but don‟t always fit the cable the way the

manufacturers connectors do.

Generally the only decision that needs to be made is whatgender of connector to install…Male or Female

Antennas – usually Female

Lightning Arrestors –

usually Female

Connectors



Connectors

N-male

RP-SMA-female

RP-SMA- male

N-female



The Lightning Arrestor

To avoid the potential for damage during a lightning strike, the

use of lightning is highly recommended.

For maximum protection, ground must be connected close to

point of entry into building - within 2ft.

Typically structural steel OK for ground connection

TypicalLightningArrestor

Do not use Gas Lines orWater pipes.

Check Electrical Code for

grounding restrictions.



Network Feasibility Assessment

Through WaveRiders Professional Services Group (PSG), a

Network Feasibility Assessment can be done to establish the

viability of a proposed wireless network with either the NCL or

LMS products.

- System and Program Planning

- Implementation Management

- Application engineering

- Network engineering

- Backhaul Design



- Electrical Inspection

Certified electrician, equipment grounding

- Primary Power Sources

- Site Lease / CostsAntenna

Floor space



Link Budget Calculations

To establish the viability of a link prior to installing any

equipment, a Link Budget Calculation needs to be made.

Performing this calculation will give you an idea as to how much

room for path loss you have, and give you an idea as to link

quality.

Using the WaveRider Link Path Analysis Tool (LPA Tool), the

Fade Margin and other link criteria can be mathematically

calculated to determine link quality.



Fade Margin – Defined as the difference between the Receive Signal

Level RSL, and the Rx Threshold or other chosen

reference Level.

– For path lengths of 16km or less, a minimum 10dB Fade Margin is recommended

Ie. If you have an RSL of – 60dB and a Rx Threshold of – 72dB,than your fade Margin would be 12dB



–Path Loss (dB)

–Field Factor (dB)

–Antenna Gain

–(dBi)

–Cable Losses

–(dB)

–Connector

–Losses

–(dB)

–Connector

–Losses

–(dB) –Cable Losses

–(dB)

–A –B

–Received Signal Level – (dBm) = Tx Output (dBm) - Path

–Loss(dB) - Field Factor (dB) + Total Antenna Gains (dB) - Total

–Cable Losses (dB) - Total Connector Losses (dB)

–Antenna Gain

–(dBi)

–Tx Output (dBm) –Tx Output (dBm)

Customer CAP1 Subscriber1

Elevation (ft)



Elevation (ft)

Latitude

Longitude

Azimuth

Antenna Type TA-2404-2 TA-2436

HAAT (ft) 50.00 40.00

Antenna Gain (dBi) 14.50 24.00

Tx Line Type LMR600 LMR600

Tx Line Length (ft) 70.00 60.00

Tx Line Loss (dB/100 ft) 4.42 4.42

Tx Line Loss (dB) 3.09 2.65

Connector Loss (dB) 1.50 1.50

Amplifier Type HA-2401E-100/10 HA-2401E-100/10

Amplifier Tx Gain (dB) 0.00 0.00

Frequency (MHz)Path Length (mi)

Free Space Loss (dB)

Diffraction Loss (dB)

Net Path Loss (dB) 116.36 116.36

Radio Type Model CCU2000 EUM2000

Tx Power (mW) 31.62 31.62

Tx Power (dBm) 15.00 15.00

Effective Isotropic Radiated Power (dBm) 24.91 34.85Effective Isotropic Radiated Power (W) 0.31 3.05

Amplifier Rx Effective Gain (dB) 10.00 10.00

Rx Sensitivity for max. Throughput (dBm) -72.00 -72.00

Rx Signal Level (dBm) -61.60 -61.60

Fade Margin (dB) 10.40 10.40

2450.004.00

116.36

0.00



Product:

EIRP= 35.5 dBm EIRP = 35.5 dBm

Distance= 8 Km

Antenna Gain Antenna Gain2 2

Pwr @ Ant 11.5 dBm Pwr @ Ant 11.5 dBm

Cable Type Cable Type

Cable Length 14 m Path Loss = 118.2 dB Cable Length 14 m

63 1

Feed Loss 3.5 dB Feed Loss 3.5 dB

Frequency = 2450 MHz

Amp Gain Amp Gain

16 3

10 10

When using amp check notes. When using amp check notes.

Output Power 15 dBm Output Power 15 dBm

Rx Power -62 dBm Rx Power -62 dBm

Fade Margin 10 dB Min. Antenna Height 14 m Min. Antenna Height 14 m Fade Margin 10 dB

Notes

Unit Converter

Enter distance in miles 18 = 29.0 km

This tool is intended as a guideline only. Enter length in feet 75 = 22.86 mIt is the user's responsibilty to ensure the link design meets the Enter distance in kilometers 20 = 12.4 miles

local regulatory agency guidelines. Enter length in meters 21 = 68.90 feet

LPASite2

MUST HAVE LOS

FRESNEL ZONE CLEARANCE - USE Calc - General for Obstruction

Site1

No Amplifier

Para 24 dBi

LMR-600

Para 24 dBi

No Amplifier

NCL1135-A

LMR-600



Interference Countermeasures

1. Short Paths

2. Narrow Beam Antennas (high gain)

3. Frequency Selection

4. Antenna Polarization

5. Antenna Azimuth

6. Equipment/Antenna Location

rf networking

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