RF Networks

There are two aspects of networking which must be considered when 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 Terminology Wavelength 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 frequency of 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.

FrequencyFrequency 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 WavelengthsVery Low Frequency VLF 9 kHz - 30 kHz 33 km - 10 km

Low Frequency LF 30 kHz - 300 kHz 10 km - 1 kmMedium Frequency MF 300 kHz - 3 MHz 1 km - 100 m

High Frequency HF 3 MHz - 30 MHz 100 m - 10 mVery High Frequency VHF 30 MHz - 300 MHz 10 m - 1 mUltra High Frequency UHF 300 MHz - 3 GHz 1 m - 100 mm

Super High Frequency SHF 3 GHz - 30 GHz 100 mm - 10 mmExtremely 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 2500PCN/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 SensitivityRx 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 electrical waves into electromagnetic waves. The amount of energy the antenna can ‘boost’ the sent and received signal by is referred to as the antennas Gain. Antenna gain is measured in:

1. dBi: relative to an isotropic radiator

2. dBd: relative to a dipole radiator

0 dBd = 2.15 dBi

There are certain guidelines set by the FCC that must be met in terms 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 LossesIn 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 MHz2400 to 2483.5 MHz5725 to 5850 MHz

FCC Part 15, Class BUnlicensed operation from 2400 to 2483.5 MHzP2P - EIRP : +36 dBm (4 Watts)

: 3:1 i.e. +24 dBm into 24 dBiP2MP - 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 bit sequence (also known as a chipping code) that divides the data according to a spreading ratio.

The transmitter and the receiver must be synchronized with the same 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 Spectrum

Also 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.

TIMETIME

11 22 33 44 55 66 77 88 99 1010 1111 1212f1f1

f2f2f3f3

f4f4

f5f5

Each channel 1MHz wide

HopsetHopsetHopsetHopset

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 (or tunnel) 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 from Free 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 SightAttaining 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*2nd* 1st*1st*3rd*3rd*

* Fresnel Zones* Fresnel Zones

Fresnel Zones

Site A

Site B• Fresnel Zone diameter depends upon Wavelength, and Distances from the sites along axis

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

d2

d1

Radius of n th Fresnel Zone given by:

21

21

dd

ddnrn

The First Fresnel Zone

When obstructions intrude on the first Fresnel Zone many issues can 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 shadow regions

The Path Profile

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

Path Profile characteristics may change 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

90

180

270 0 -3 -6 -10

-15

-20

-30dB

0

90

180

270 0 -3 -6 -10

-15

-20

-30dB

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. The better 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. A figure 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

-50

-40

-30

-20

-10

0 5 10 15 20 25 30 35 40 45 50 55 60

M1

Distance-to-faultCHER-B-A04

Model: S332B Serial #: 00004096Date: 06/27/2000 Time: 12:03:59 BiasTee: OFF Output Power: -30.00 dBmResolution: 259 CAL: ON(COAX) CW On

Ret

urn

Loss

(dB

)

Distance (0.0 - 60.0 Feet)

M1: -3.728 dB @ 50.698 Feet

Environmental EffectsIce and wind loading, Salt spray

Radomes 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

Andrew Corporation Heliax

Times MicrowaveLMR 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 GHzper 100 feet

RG8 10LMR400 6.8Heliax 3/8" 5.36LMR600 5.4Heliax 1/2" 3.74Heliax 5/8" 2.15

Attenuation Table

Transmission Line Selection

Physical Characteristics:Bend radiusDiameter - transition considerations (interface ‘jumper cable’ use)

Environmental considerationsPlenum installation (fire retardant)Special weather-resistant typesUV 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

ConnectorsYour connector selection will be determined based on the following:

- 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 manufacture the 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 what gender of connector to install…Male or Female

Antennas – usually Female

Lightning Arrestors – usually Female

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

Typical Lightning Arrestor

Do not use Gas Lines or Water 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 InspectionCertified electrician, equipment grounding

- Primary Power Sources

- Site Lease / CostsAntennaFloor space

Link Budget CalculationsTo 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)Latitude

LongitudeAzimuth

Antenna Type TA-2404-2 TA-2436HAAT (ft) 50.00 40.00

Antenna Gain (dBi) 14.50 24.00

Tx Line Type LMR600 LMR600Tx Line Length (ft) 70.00 60.00

Tx Line Loss (dB/100 ft) 4.42 4.42Tx Line Loss (dB) 3.09 2.65

Connector Loss (dB) 1.50 1.50Amplifier 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 EUM2000Tx Power (mW) 31.62 31.62

Tx Power (dBm) 15.00 15.00Effective Isotropic Radiated Power (dBm) 24.91 34.85

Effective Isotropic Radiated Power (W) 0.31 3.05Amplifier Rx Effective Gain (dB) 10.00 10.00

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

Rx Signal Level (dBm) -61.60 -61.60Fade Margin (dB) 10.40 10.40

2450.004.00

116.360.00

Product:EIRP= 35.5 dBm EIRP =35.5dBm

Distance= 8 KmAntenna Gain Antenna Gain

2 2

Pwr @ Ant 11.5dBm Pwr @ Ant 11.5dBm

Cable Type Cable Type

Cable Length 14m Path Loss = 118.2 dB Cable Length 14m63 1

Feed Loss 3.5dB Feed Loss 3.5dBFrequency = 2450 MHz

Amp Gain Amp Gain16 310 10

When using amp check notes. When using amp check notes.Output Power 15dBm Output Power 15dBmRx Power -62dBm Rx Power -62dBmFade Margin 10dB Min. Antenna Height 14 m Min. Antenna Height 14 m Fade Margin 10dB

Notes

Unit Converter

Enter distance in miles 18 = 29.0km

This tool is intended as a guideline only. Enter length in feet 75 = 22.86m

It is the user's responsibilty to ensure the link design meets the Enter distance in kilometers 20 = 12.4miles

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

LPA Site2

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