Communications Panel discussion ITE/IMSA 2016 - Simrex.pdf–The units of measure are dB, and dBm –GOOD: RF power, ... RSL = Tx Power - Tx Cable Loss ... RSSI can remain high but

Communications

Panel discussion

ITE/IMSA 2016

Frank Neuperger

General Manger and CTO

SIMREX Corporation

SIMREX CORPORATION

Founded 1990

Located in Buffalo NY.

Systems integration and wireless technology development history.

Acquired assets and exclusive rights to Aria Wireless and GLB Electronics product lines 2001

Legacy Product was SCADA and high reliability telemetry for government/military/industrial applications.

Entered traffic market in 2004 with products based on proven core wireless technology.

SIMREX CORPORATION

•

Traffic/ITS – Card cage, wide band radios, GPS timing, sensors and other traffic/its related functions.

SCADA – Contact closure radio, VHF/UHF,

hazardous environments.

• Transportation -Aviation, Rail.

Military/Aerospace – Semi-custom variants of standard products.

VITAL SYSTEMS

NASA, Calibration of Shuttle Landing System.

FAA and International equivalents, Multiple

Applications including vital systems.

Aerospace Flight testing, range safety.

Chemical warfare detection.

Railway Control.

TRAFFIC APPLICATIONS

Interconnect controllers at street Intersections

Bridging Wire-line Interconnects

Coordination (GPS or radio)

Contact closures, pre-emption

Control of programmable signboards

Custom logic/algorithm capability (eg. Crosswalk)

Wireless ITS APPLICATIONS

Roadside Animal Detection and Warning (RADS)

Vehicle Safety Barrier runoff monitoring (I-75 SBCS)

Travel time by Bluetooth Monitoring

CCTV Cameras

Bridging isolated fiber runs

School zone flashers and crosswalk control

Firehall and truck based pre-emption.

DataMover

ODU (RS232)

WB (Ethernet)

DataMover™ Traffic Products

DataMover

DR(M)

DataMover

170 T(M)

DataMover

SS Traffic

DataMover

I/O

DataMover

ATC/2070

Firehouse Based Preempt

(DataMover Preempt)

New Remote Control

(DataMover IO Hand Held)

Ferry Boat Loading

Work Zone

Simsync (RMC)

Once per day GPS accurate time synchronization

Controller specific time/date message

Once per day contact closure

Vandal resistant

Quick installation

Electromechanical controller mode

Serial messages for Siemens (epac), Econolite and AB3418 compatible Controllers

RMC version is GPS antenna only (NMEA GPRMC message)

Ethernet/POE Extender

100 Mbit Ethernet up to 1800 feet Cat6 without mid-span devices.

Variants available that also provide 24V or 48V POE 12 - 25W.

Traffic Cabinet mounted base unit.

IP67 weather resistant termination unit

Termination unit provides 328 additional feet of cable drive.

Typical apps are to communicate with and power Cameras or Radios.

Turnkey Systems Solution

FDOT Roadside Animal Detection


FDOT I75 Beacon system

300 Nodes along ~50 miles of Highway, Solar powered IP solution

Wireless connection to all remote nodes.

Detect vehicles that hit the fence and land in swamp

Less than 15 second notification by SMS email, console.

SIMREX Proxy server Interface to FDOT Sunguide system.

Wireless Trends:

DEVICE COMMUNICATIONS

Less serial and more IP devices.

Wider digital bandwidth to support CCTV. Less analog.

Use of Bluetooth and Wifi MAC sniffing as travel time sensor.

More encrypted communication

FREQUENCY, MODULATION, Protocol

• Less use of 900MHz, more 5800, 4900 and 3600

• Some shift of 900 MHz to WB 900 MHz.

• Less hopping/GMSK/FSK and more OFDM.

• More Licensed frequencies available 4900, 3600, 1800 (Canada)

• 802.11 at many freq’s. TDMA at unlicensed freq’s.

TOPOLOGY

• Less use of central base and more corridors with backhaul

• Use tree/loop of fiber and last mile or 3 with radio.

Wireless Concepts

Radio Speed and Bandwidth

The Link Budget and Fade Margin

Fresnel zone clearance

Frequency, 900 MHz vs. 2400 or 5800 MHz

RF Interference

Antennas

Sharing unlicensed spectrum

Diagnostic tools

Radio Speed and Bandwidth

Higher data speed requires

Wider bandwidth (letting in more noise, thus less sensitivity)

and/or

Signal structure that requires higher SNR (signal to noise ratio) or lower noise floor.

For best range and interference rejection

Use the narrowest bandwidth possible

Use the lowest data speed possible.

Radio Network Topology

CENTRAL BASE, RADIAL REMOTES.

Single BASE and all remotes aim back at Base.

High central antenna susceptible to more noise/interference.

MESH

Grid of many peers that can find alternate paths between them.

Extensive use of omni antennas shortens range and requires ~4-5x as many radios to cover the same area.

Easy to deploy.

Bandwidth is non deterministic and affected by other users sharing the spectrum.

CORRIDOR

Engineered system of narrow beams that follow street corridors.

Excellent frequency reuse and bandwidth.

Low number of radios for given coverage.

Radios are individually configured for the topology.


• Link Budget

– Like a balance sheet with line items that add or detract from your

ability to have a viable link.

– The units of measure are dB, and dBm

– GOOD: RF power, antenna gain, more receiver sensitivity.

– BAD: cable losses, distance, higher frequency.

– A good sanity check and training tool to learn unmodeled losses.


• Fade Margin (a.k.a. System Operating Margin)

– The bottom line of the Link budget.

– The number of dB that the link exceeds or fall short of providing a

viable link. + is good - is bad.

• The MATHFree Space Loss = 20Log10(Frequency in MHz) + 20Log10 (Distance in Miles) + 36.6

RSL = Tx Power - Tx Cable Loss + Tx Antenna Gain - FSL + Rx Antenna Gain - Rx

Cable Loss


Unmodeled losses

What if measured RSSI (signal strength) is less than the predicted

received signal level with the fade margin calculator?

This difference is either a faulty component or antenna alignment or

unmodeled loss.

Common causes of unmodeled loss:

• Foliage

• Fresnel loss due to terrain or buildings

• Other more complex NLOS loss

• Desensitization due to strong signal nearby.

Catalog these unmodeled error types to build your RF path

engineering experience. Use a spreadsheet. In the future, you can

then more easily predict path viability without need of a link test.

Fresnel Zone Clearance

• Direct visual path (line of sight) is important but it is

not enough

• You need some need some extra clearance “r” in all

directions around the direct path line.

• r increases for lower frequencies or longer distance.

Fresnel Zone = 72.1 * Sqrt (d / (f * 4)) where d is in miles and f in GHz


• Because of the wave nature of radio signals, grazing an edge can increase or decrease the strength of signals that are above or below the edge. The mechanism operates by constructive and destructive interference.

• The edge can be anything. Sideways: A building very close to the street. Above: A sign or bridge above the line of sight.

• If you can see from one antenna to the other, you have OPTICAL or VISUAL line of sight.

• If you have adequate Fresnel clearance, you have RF line of sight.


Fresnel Loss Quantified



2 km (1.25 mi) RF path

Frequency = 900 MHz

Mid path obstruction cases at -25 m, 0m and +25m

Fresnel Losses:

-25 m = -1 dB (25% loss)

0 m = -6dB (75% loss), Just grazing.

+25 m = -24 dB (99.6% loss) ok with 30 dB fade margin!

From: http://people.ee.duke.edu/~gary/ECE486/ECE186lecture9.pdf

Line of Sight or Not

• Optical Line of Sight

• RF Line of Sight

• Non (RF) Line of Sight (NLOS)

• near Line Of Sight (nLOS)


• Optical Line of Sight

– Can see from one end to the other (possibly need telescope).

– Does not guarantee Received Signal Level (RSL) is acceptable.

– Even RSL is acceptable the signal can be distorted to the point of

very little throughput of force cyclic disconnect/reconnect attempts.

• RF Line of Sight

– Implies that the path has reasonable Fresnel path Clearance 0.6F1.

This mainly assures acceptable RSL.

– In a reflection free environment with full Fresnel clearance, this also

assures minimum distortion due to Multipath reflections.


• Non Line of Sight (NLOS)

– Can’t optically see from one end to the other.

– Can’t “RF see” from one end to the other without loss of signal due

to absorption (foliage) or scattering (foliage, wires, signs poles…).

– Multipath due to reflections is common.

– RF modulation called OFDM (Orthogonal Frequency Division

Multiplexing) can greatly diminish detrimental impact of Multipath as

long as RSL is above receiver threshold plus some fade margin.

Link Quality

• Is strong Received Signal Level (RSL) good enough?

a.k.a. RSSI

Link Quality

• With strong multipath (reflected signals) RSSI can

remain high but the signal is distorted and results in

poor throughput.

• Validate performance with bandwidth check.

• Investigate BW deficiencies with Interference check

and channel quality check.

Frequency, 900 vs. 2400 or 5800 MHz

• Higher frequencies

– Less Fresnel zone clearance required.

– More antenna gain with a specific physical size of antenna.

– Better antenna directivity with a specific size of antenna.

– Shadowed or blocked more easily in most cases.

– Better frequency reuse because of the ability to use narrow beam

width antennas.

• Lower frequencies

– For the same RF power EIRP and gain of antenna, allow a better

link budget.

– Have less allocated (unlicensed) spectrum

Frequency, 900 vs. 2400 or 5800 MHz

• PARAMETERS: ANTENNA GAIN, LOSSES, TX POWER,

RX SENSITIVITY

• With all parameters fixed, 915 MHz has ~8.5 dB

advantage over 2440 MHz.

• With all parameters fixed, 915 MHz has ~16 dB advantage

over 5800 MHz.

• BUT THE PARAMETERS ARE NOT REALLY FIXED!!

• 900 MHz penetrates foliage better but has less spectrum.

• 5800 provides excellent directivity (frequency reuse) and

wide bandwidth.

RF Interference

• Co-channel - same channel

• Desensitization – nearby band overpowers receiver front end

• Multipath – destructive cancelation of some part of your channel

• Intermodulation – mixing of 2 signals co-channel

• Harmonic – distortion component of another carrier -> co-channel

Interference Remedies (null steer)

• Antenna is aimed directly at the desired carrier but

also sees equal power interference at 30 degrees off of

the main beam.

C=carrier

I=interference

• C=0 dB I= -4 dB

• C/I is 4 dB in this case, marginal


• Steer the null of antenna to suppress co-channel or

desensitization interference. Rotate by ~ 30 degrees

• Sacrifice 4 dB of carrier

C=carrier

I=interference

• C= -4 dB I= -17 dB

• C/I is 13 dB in this case, 9 dB (8x) improvement


• Steer the null of antenna even more to suppress co-

channel or desensitization interference.

• Sacrifice 8 dB of carrier

C=carrier

I=interference

• C= -8 dB I= -30 dB

• C/I is 22 dB in this case, 18 dB (64x) improvement

Interference Remedies (polarization)

• Cross polarize antenna against the interference.

• Benefit can be 10 to 20 dB suppression with 15 dB as

typical.

• Vertical pol. is very common for SCADA systems.

• Test your environment with spectrum analyzer with

both vertical and horizontal polarization to validate the

amount of benefit.

• The benefit is realized as improved Carrier to

interference ratio (C/I or CIR) and possibly diminished

desensitization.

• Horizontal polarized omni available but premium price.

Interference Remedies (desensitization)

• Cross polarize antenna against the interference.

• Vertical separation WITH NO OVERLAP.

• Horizontal polarized omni available but premium price.

• Steep filters combined with the above can help

• Synchronization of radios (if supported).

Antennas

• Gain, dBi vs. dB vs. dBd

• Beamwidth vs. gain.

• Clearance to pole or nearby objects.

• Clamp to element clearance

• Use signals from rear of yagi antenna

• Splitters.

• Lightning Arrestors

Antennas

• Gain, dBi vs. dB vs. dBd

9 dBd = 11 dBi (2 dB difference)

• Beamwidth vs. gain.

Narrow beamwidth = higher gain

Antennas

• Lateral clearance to pole or nearby objects that are not in front of the antenna mast.

– 18 inches for 900 MHz yagi

– ½ panel dimension for panels.

– Increase distance for objects in front of antenna mast per Fresnel zone profile.

• Why? because these objects act as reflectors and distort the beam of the antenna. Further separation, means less distortion.

• Even non metallic objects can reflect. eg. concrete surface of pole.

• Mast clamp to Yagi element clearance

– As far back as mechanically possible without loss of grip on antenna boom in order to avoid interfering with rear reflector.

Antennas NOT

More Antennas NOT

Antennas

• Is it ok to use signals from rear of a yagi antenna

• Front = 9 dBd, rear = -15 dBd

Antennas on a Splitter

• Splitter 3.25 dB loss for each antenna

– 9 dB becomes ~5.6 dB antenna when including the cable/connector losses.

– 3 extra RF connections to seal.

– 2 extra vulnerable RF cables.

– Not aesthetically pleasing.

– Cost of spit antenna system is ~3.5x the cost of a single antenna.

• Use Back of Yagi?

– Using the rear of antenna yields 24 dB lower fade margin than the front.

– For nearby locals that would have 50+ dB of fade margin anyway, this still leaves 26 + dB fade margin.

– 2 way antennas available but high cost.

Lightning Arrestor

– Low cost = high feed through

• 300V to 600V typical

• Often advertised as “high power” good for “750W”

• Many high power arrestors don’t trigger until hundreds of volts have reached the radio.

• Gas tube is often single use and impairs communication after it has triggers.

– Higher cost = low feed through

• 3V to 10 v peak typical

• Optimized for lower power radios.

• Technically more difficult to make hence the premium price.

Radio Specmanship

Sensitivity

-108 dBm 1e-6 BER = -110 dBm 1e-4 BER for GMSK

FEC and retries improves the rating as well. Many manufacturers state sensitivity at high BER with retries and FEC turned on. It is impossible to know without asking.

Sensitivity and data rate.

You cant have the highest sensitivity and the highest data rate at the same time.

Unfortunately many bid specs don’t specify sensitivity at a specific data rate. Some seriously deficient radios capable of multiple data rates sometimes get selected by easily passing through this screening.

RF Power Control

1mW, 10 mW, 100 mW …. vs. 1 dB stepsBER –> Bit Error Rate

Sharing Unlicensed Spectrum

Spectrum issues

FHSS (frequency hopping) .

Separate channels (DSSS and DTS)

MAC sharing (802.11)

Radiation issues

Directional antennas to keep beamwidth narrow.

Polarization

Use minimal power. USE MINIMAL POWER.

BER –> Bit Error Rate

Path Planning Tips for ITS/Traffic:

• AP’s (Access points or Bases) for point to multi point corridor

systems should have the AP’s on elevated risers.

• Keep all antennas to the centroid of the corridor.

• Validate any exceptions with zoom photography.

• Ok to test worst case paths for each corridor.

Testing Results Spreadsheet should have:

• Speed of each RF link in each direction.

• Signal Quality of each link if available

• Measured RSL/RSSI of each RF link. Yellow flag if 20 db lower

than theory or stronger than -25 dBm.

• Theoretical free space RSl/RSSI of each RF link.

• TX/RX speed of ETH link to each radio (to validate new cable).

Path Planning and Testing Checklist:

• Spectrum Scan for each AP location. Record data for designer to do

frequency selection. If single polarity radio, test in both polarizations.

This can be a telescopic tripod test if budget is constrained.

Test Data spreadsheet:







Comissioning/Benchmarking Checklist

• Visual sanity check on alignment of each antenna.

• Insist that installers use an optical sighting alignment tool on

narrow beamwidth panel antennas.

• Redo spectrum scan for each AP location if more than 90 days

since the RF path validation was done. Best frequency choice

may be different now.

Create Spreadsheet with:







RF Path Validation in Traffic/ITS

– Actual test.

– Sanity check on Google maps .

– Photography.

Path Planning in Traffic/ITS



• Street level


• Bucket truck at 35’


– Use telephoto photography with high zoom 10 to 30x to

visualize/validate the clear centroid and any midpath obstructions.

– Locate the AP (master)antennas at each end so that the path is

centered in the tunnel. Locating on sidearms mid street or mid-lane

incase of median with corridors is best. Locate 8+ feet above the

sidearms to avoid shadowing of other sidearms midpath.

– Less desirable is diagonal shots from luminaires at side of stree

due to close range Fresnel obstructions such as lamp head of the

next luminaire. Locate well above luminaire if forced to do this.

Path Planning with Zoom Photography

Path Planning with Zoom Photography

Path Planning with Google Earth

Tools

Radio configuration software

Remote Diagnostics

WEB RF path analysis tools

Real time spectrum analyzer

Path Benchmarking Tool.

WEB tools at www.simrex.com “free tools”

http://www.simrex.com/

Spectrum Analyzer

• Horizontal vs. vertical polarization noise floor

• Out of band vs. in band signals.

• Desensitization test.

• Recording all sweeps and results to file.

Standard

ITS/Traffic

Wireless Applications

System design and Commission

Wireless Network and PTZ Cameras

Simrex design/configuration. Customer installed.

100 IP Nodes and growing. 15 serial nodes.

Support controllers (serial or IP). Preemption (IP). PTZ cams (IP).

Some nodes solar powered.

Extension and bridging of fiber.

Fiber alternative was ~ 15x the cost.

Done in 1/4 of the time it would have taken to install fiber.

Simrex Datamover WB 5800 radios. 6-108Mbps & 6 –300 Mbps.

Simrex MS-5 managed switches.

Simrex pressurized PTZ IP Camera’s

Simrex CRMS network management software

Factory configured and staged for plug and play deployment.

System design and Commission

Wireless Network

Simrex design assistance and configuration. Customer installed.

~75 wireless IP Nodes and growing.

Support controllers (serial over IP or IP). PTZ cams (IP).

Extension of fiber.

Simrex Datamover WB 5800 radios. 6-108Mbps.

Simrex CRMS network management software

Factory configured and staged for plug and play deployment.

Unusual

ITS Wireless Applications

















26 beam traps along 1.4 miles of US41 in Everglades

Focused on protecting endangered Florida Panther

Developed long range low power IR beam trap.

Solar powered IP accessed solution (0.5W LINUX PC)

Logging of all events and battery voltage over time.

Wireless (DM-IO-900) connection to all remote nodes.

http://sim-rads2.eairlink.com/www/RADS/status.php

Broward based on php revised with clean pics (Frank N's conflicted copy 2012-08-20).ppt



TRAFFIC APPLICATIONS

Interconnect controllers at street Intersections

Bridging Wire-line Interconnects

Traffic light status, alarm status

Time synchronization (GPS or radio)

New schedule download.

Contact closures, pre-emption

Control of programmable signboards

Custom logic/algorithm capability (eg. Crosswalk)

Wireless ITS APPLICATIONS

Roadside Animal Detection and Warning (RADS)

Vehicle Safety Barrier runoff monitoring (I-75 SBCS)

Travel time by Bluetooth Monitoring

CCTV Cameras

Bridging isolated fiber runs

School zone flashers and crosswalk control

Firehall and truck based pre-emption.

SimSync and SimSync RMC.

Firehall Preempt.

Crosswalk controller.

DataMover DRM portshare.

Road-side Animal Detection System.

Fence line Breach Monitoring

Products developed at Dealer or end User

Request:

DataMover WB and options

Ethernet 1.5 - 300 Mbps

900 / 2400 /3600/ 4900 / 5800 MHz

12.5, 20 or 23 dBi integral antennas or dish/omni

Serial data option. Serial data + Ethernet

Mesh capability

DataMover WB and options


900 / 2400 / 4900 / 5800 MHz

12.5, 20 or 23 dBi integral antennas

Selectable video optimized protocol standard.

Integral and External Antenna versions

Dual or quad radio capability

5, 10, 20 or 40 MHz Channels

Split antenna capability

POE , power supply and mast clamp included

Router or bridge capability.

Multiple video stream mode.

Serial data option. Serial data + Ethernet

Mesh capability

DataMover WB 2x2

Same as DM WD with the following exceptions


2400 / 5800 MHz

Dual Gigabit ETH ports

19 or 23 dBi integral dual polarized antenna at 5800 MHz

30 or 34 dBi dish antenna.

SIMREX CRMS

(Central Radio Management System)

Radio network visualization and management

Map view as well as hierarchical view.

Monitor SIMREX radios and switches

Monitor availability of third party radios and devices

Email notification of alarms on all devices.

CONTACT :

Dlr_xxxx.com

SIMREX CORPORATION

www.simrex.com

Documents

Communications Panel discussion ITE/IMSA 2016 - Simrex.pdf–The units of measure are dB, and dBm –GOOD: RF power, ... RSL = Tx Power - Tx Cable Loss ... RSSI can remain high but