Digital Leakage Today Analog and Digital Leakage LTE interference - - PowerPoint PPT Presentation

< HOME

Digital Leakage Today

Analog and Digital Leakage LTE interference

Kendall Robinson Regional Account Director Arcom Digital

< HOME

Outline

• Digital Leakage
• Traditional Leakage
• LTE
• Ingress and Egress issues
• QAM Snare overview
• Analysis of results at 3 leakage demo trials

Digital Leakage

< HOME

< HOME

Traditional Signal Leakage Today

• Most legacy leakage systems are in the aeronautical band from 108 to 137MHz
• A common frequency is 133.26MHz (Visual CEA channel)
• Max allowed signal strength at 10 feet is 20uV/m
• Many operators target to fix all leaks greater than 10uV/m
• Some fix above 5uVm
• A few have a goal to fix any size leak on their system

< HOME

Signal leakage regulations in Part 76 of the FCC’s Rules. The following table, taken from §76.605(a)(12), states the maximum allowable signal leakage field strengths across various frequency ranges:

Signal Leakage Regulations

Frequencies Signal leakage limit in micro- volt per meter (uV/m) Distance in feet (f) Distance in meters (m) Less than 54MHz 15 ~100 30 54MHz to 216MHz 20 ~10 3 Over 216 MHz 15 ~100 30

< HOME

< HOME

Distance at 10 feet is 20uV/m larger

Signal Leakage Regulations

Frequencies Signal leakage limit in micro- volt per meter (uV/m) Distance in feet (f) Distance in meters (m) Over 216 MHz 15 ~100 30 Over 216 MHz 150 ~10 3

< HOME

LTE Overview

• LTE means (Long Term Evolution)
• Downlink: OFDM - (QPSK, 16QAM and 64QAM)
• Uplink: SC-FDMA (QPSK and 16QAM)
• Paired Duplex: FDD (Frequency-division duplex) – paired downlink and uplink
• Bandwidth: 5 and 10MHz (typical in the US)

< HOME

OFDM is a broadband multicarrier modulation method that

• ffers superior performance and benefits over older, more

traditional single-carrier modulation methods because it is a better fit with today’s high-speed data requirements and

• peration in the UHF and microwave spectrum.

Orthogonal Frequency Division Multiplexing

< HOME

What makes LTE different to Traditional Cell technology?

• LTE in the USA is in the 698-806 MHz band

which falls in the CATV frequency band

• Compare to traditional cell (CDMS and GSM)

at 1.8GHz, 1.9GHz and 2.1GHz.

• LTE is of particular concern for Cable systems

with 750 MHz, 850 MHz and 1 GHZ systems.

• Signals in the 700 MHz band (compared to

traditional cell signals) travel further and are less attenuated by structures.

• OFDM in the downlink side has a higher

potential power spectral density than traditional cell signals. (These change)

• When there are fewer resource blocks and the

total signal power is divided among fewer

• subscribers. There is a higher probability of

ingress as the energy is concentrated to a smaller allocated bandwidth. Especially an issue in the LTE uplink.

< HOME

LTE bandwidth and frequency allocation

• LTE bandwidth is allocated in “Resource Blocks” allowing signal sharing by

multiple users

• “Resource Blocks” are a set of subcarriers and OFDM symbols
• For a 10MHz signal there are 50 “Resource Blocks”. (5 per 1MHz)
• There are correlations between “Resource Blocks” and Interference
• Frequency Allocations:
• Band 13 (DL 746-756 MHz, UL 777-787 MHz) for Verizon
• Band 17 (DL 734-746 MHz, UL 704-716 MHz) for AT&T.

< HOME

US FCC 700MHz LTE Bands

< HOME

The potential future of expanded LTE

• LTE currently only in the 700MHz spectrum
• It is highly likely in the future LTE will be even lower from 570 MHz to 780 MHz.

(Currently 730 MHz to 790 MHZ)

• Plans are being proposed to vacate Broadcasters from OTA channels 31-51 (572-698

MHz) and auctioning off this valuable spectrum.

• In Feb 2013, T-Mobile starts discussion with the FCC to repurpose the entire 600MHz

band for LTE since AT&T and Verizon already are using 100MHz of the bandwidth.

< HOME

LTE Ingress Interference

LTE interfering with the CATV system

• LTE can interfere with STB’s, Cable Modems and TV’s at the customer

premise

• Cable Modems are susceptible to even low LTE emission levels
• Most frequent issues to customers devices are direct pickup due to lack of

sufficient shielding of the equipment.

• This interference has been shown to even be through steel and concrete

barriers

• Interference also enters on the cable plant where there are areas of

damaged cable and connectors (potential leak locations)

Ingress: RF signal leaking into the coaxial plant..

< HOME

Influences of digital leaks on communication systems

• Ingress from LTE can be a big issue when leakage affects QAM and Broadcast

channels.

• Of course cellular transmission can also affect these channels.

< HOME

• Leaking CATV devices using a portable spectrum

analyzer and directional antennas.

• R&S

What ATT and Verizon are finding

< HOME

< HOME

Courtesy Verizon

Here the measurement was made at a distance of ≈ 10 ft with an 11dBi Yagi at 780 MHz. The signal level at the top of the QAM at the input of the SA is ≈ -25dBmV for the 30kHz

• ResBW. The field strength

calculation at 10 ft comes out to a substantial 2200µV/m.

< HOME

Courtesy Verizon

< HOME

Courtesy Verizon

< HOME

Courtesy Verizon

< HOME

Courtesy Verizon

< HOME

Courtesy Verizon

< HOME

Courtesy Verizon

< HOME

Courtesy Verizon

< HOME

Courtesy Verizon

< HOME

• Holes in Cable
• Thin Cracks / ring cracks in Cable
• Leaking Tap Face Plates / Bad fitting of the metallic gasket
• Broken connectors
• Loose Connectors
• Illegal connections

What CATV operators are finding – causes of high frequency leakage

< HOME

LTE Egress Interference

The CATV system interfering with LTE Egress: RF signal leaking out of the coaxial plant.

• We will look at multiple examples of this.
• Typical locations that cause these issue are: Loose or damaged hardline

connectors, insufficiently shielded splitters, switches, amplifiers, as well as unterminated outlets which are common egress sources. Keep in mind that any egress locations are potential ingress locations for the CATV system as well.

• In addition, common physical defects responsible for egress include ring cracks in

the coaxial cables, damage from chewing/gnawing by animals, loose covers, loose hardline connectors, faulty AGC, etc.

• Illegals: Connections and alterations made by persons engaged in cable theft

have also been reported as a serious source of problems: improperly spliced cables, poor-quality materials, etc.

• Adding a Digital Leakage program in the upper band frequencies can ensure a

much tighter plant.

< HOME

What we have discovered about Leaks at higher frequencies

• No real correlation or reason why some leaks are higher at low or high

frequencies

• In many cases a very high leak in the 700MHz band will show no leak in the

VHF frequency band

• These higher frequency leaks are typically at higher levels
• Possible reason are:
• In some part due to the tilt on outside plant
• Also higher frequencies travel more efficiently
• Mostly due to the component that is leaking
• Eg: cracks in the cable, leaking RF tap gasket, hole in cable

< HOME

Digital Leakage Detection

> This is a location where a tree grew through

a cable on a busy thoroughfare a few blocks from a hub.

> Hundreds of service vehicles drove past this

location every day. It was a small analog leak that wasn’t worth stopping for. (8uV/m – low)

> No correlation between low and high

• frequency. (We show this in the next few

slides)

> Very High leakage at 735MHz >

Monitoring at just one frequency will not allow you to detect all leaks.

> QAM Snare simultaneously detect leaks at

Multiple Frequencies

< HOME

The technology

> The process whereby QAM Snare detects and

pinpoints leaks is fairly straightforward to explain:

1.Samples of the QAM channel are taken at the

headend and transmitted to the field unit over a wireless network. *

2.The field unit compares these samples with

signals pulled off of its antenna – when there is correlation and the two signals are the same – a leak has been detected.

3.After detection the next step is resolving the

exact GPS coordinates of the leak, which is accomplished through an advanced technique called TDOA – time difference of arrival.

* With the QAM Snare Isolator used in the home, samples are acquired locally

< HOME Time difference of arrival (TDOA) – hyperbolic location

Advanced location methodology

• Because of the employed

correlation detection process and inherent time delay

• utput – we have a unique
• pportunity to make use of

this data and employ the most accurate location methodology called Time Difference of Arrival (TDOA) to resolve the GPS location of the leak.

• QAM Snare is impervious to

multipath/standing wave type issues that are prevalent with analog detectors – thereby making the final isolation process significantly easier.

< HOME

Simultaneous three channel detection

• QAM Snare is designed to detect and record leakage from any three digital

channels simultaneously

• Typical choices are Aeronautical (130 -200MHz) , Mid-band (550MHz) and

LTE (750MHz) 567MHz 579MHz 729MHz

< HOME

• You would think that a leak acts like a wideband antenna but it does not.
• Can you still have a leak if traditional leakage in the 108 to 140 MHz range

show nothing?

• Findings show little to no correlation across the spectrum. Leak strength at one

frequency shows no correlation to leak strength at another.

• What does this mean for operators?

Understanding a Leak

Is it the same level at low and high frequencies?

< HOME

Low Frequency

• nly

Low and High Frequency High Frequency

• nly

Lack of correlation of leaks from one band to another

< HOME

Combined leaks on one graph

< HOME

Leaks in different frequency bands are due to different sets of problems

Aeronautical band below 200MHz 300Mhz to 500MHz 600 to 900MHz

96% drops and soft cable issues 40% drops-60% small cable issues and loose devices 90% Hard line issues and 10% other and LTE

< HOME

3 Channel Detection

Red Flags are leaks >100uV/m, Yellow 20-100uV/m, Green <20uV/m We’re seeing on average one high frequency leak per mile. Operators don’t have the manpower or time to fix all of these leaks of varying levels. It’s imperative that operators accurately measure the leak levels affecting the LTE band in order to prioritize where to work.

< HOME

3 Frequency Leakage Comparison

A sample of some interesting leaks from a deployment. QAM Snare was set to do 3 frequencies simultaneously. There is a wide range of differences in leak levels between 141Mhz, 561MHz and 711MHz.

< HOME

Dramatic Differences in Frequency Response

This tap was leaking 112uV/m at 729MHz. With an 18dB difference between 600MHz and 700MHz, the leak would only measure 14uV/m around 600MHz. 14uV/m is probably not a level that an operator would prioritize to fix yet this device was clearly causing LTE interference and had a higher leak in the LTE band.

< HOME

Benefits of frequency agile detection

• Better coverage of your

network

• Better network performance

by focusing on frequencies being interfered with or causing interference

• The ability to assign work

based on skill level and job focus

• Ability to know and schedule

work to prevent issues now and in the future

• Better protection of your

network

• Right technician for the area
• f focus

< HOME

< HOME

Implementation options:

Navigator and Isolator used in companion to find and fix leaks:

Navigator:

• Permanently mounted in

vehicle

• Gets the technician to the leak

zone

• Data bridge to Isolator
• Can switch to different

frequencies as necessary Isolator:

• Used for close-in

troubleshooting of the exact device

• Displays what the Navigator

currently sees (Truck mode) or displays leaks measured off of its antenna (Walk mode)

QAM Snare Isolator: QAM Snare Navigator:

< HOME

Implementation options:

Monitor used for passive detection – repair later:

Monitor:

• Permanently mounted in

vehicle

• Continuously reports

leaks data to Headend Signal processor

• Designed to detect and

locate leaks with no user involvement

QAM Snare Monitor:

< HOME

Monitor, Isolator, and Web Client used in companion to fix previously identified leaks.

Web Client:

• Use Google maps to display the

location of known leaks.

• Display Work Orders
• Fix and update leaks status in

real time.

• Either PC or smartphone based

Monitor:

• Data bridge to Isolator

Isolator:

• Truck mode or Walk mode
• In Truck mode will provide

audible feedback

QAM Snare Isolator: QAM Snare Monitor:

Implementation options:

QAM Snare Web Client

< HOME

QAM samples and timing over ISM transceiver chipset

Implementation options:

Isolator pair - for the fulfillment technician to detect leaks within the home.

Isolator in the transmit mode:

• Acquires samples locally, sends

to the second isolator with antenna

• Connect to a drop anywhere in

the house Isolator in the detector mode: Walk around the home or MDU to find the source of the leak.

< HOME

QAM Snare

System Demo Location #1

< HOME

Flag 89 – 158uV/m at 711MHz 5868 Beachwalk Dr

At Flag 89 we found a cracked tap housing that subsequently broke off. No analog leak was found.

< HOME

Flag 86 – 100uV/m at 711MHz 5876 Goulagong Dr

Burnt out tap with suck out around 470MHz..

< HOME

Flag 111 – 200uV/m – 5397 Gale Dr

• At this location the tap was missing a screw in the tap plate. This is a

good example of our TDOA technology for calculating the GPS coordinates of a leak.

• As can be seen from the screen shot in the Client software, the QAM

Snare Navigator had visibility to the leak from a far distance as indicated by the red data points.

• TDOA put the flag at the exact location of the leak.

< HOME

Flag 53 – 224uV/m at 711MHz 5902 Woodstock Ct

Radial crack in the feeder cable.

< HOME

Flag 80 – 224uV/m – 5878 Clear Springs Rd

Drop cable had crimp on connector. Pulled drop cable out of the connector. This dropped the leak down in level but a smaller leak was still detected. The tap screws were also loose.

< HOME

Flag 52 – 251uV/m – 749 Fiona Ln

At Flag 52 a PDU taps screws were extremely loose. The tap also showed a bit of corrosion. A second lower level leak was found at the next pole. The cause was also loose screws on a PDU tap.

Flag 52 2nd Tap

< HOME

QAM Snare

System Demo Location #2

< HOME

Leak #1 at this location: Tech first found a bad drop with an old Digicon connector with the center pin loose. The tech replaced the F connector, reconnected the drop and the leak at 435 MHz dropped to zero. This was the cause of the 435MHz leak, but had nothing to do with the 729MHz leak which still remained.

Two Leaks at one location Flag 7 – 500uV/m @ 729MHz 80uV/m @ 435MHz

Leak #2 at this location: Tech checked the tap face plate and found that the gasket was twisted. To correct the gasket the tap plate was removed, and the gasket and tap plate were reset. This action cleared the leak at 729 MHz.

< HOME

Leak level recorded at Isolator in bucket truck next to amp 729 MHz / 2100 µV/m 435MHz /3800 µV/m Resolution: First Leak #1 at this location: The technician found the power passing tap face plate to be loose. The tech tightened the face plate and the leak at 729 MHz dropped to 500 µV/m.

Three Leaks at one location Flag 4 – 380uV/m @ 729MHz 398uV/m @ 435MHz

< HOME

Resolution: Leak #2 and Leak #3 at this location: The tech realized that the back part of the tap was still loose and after looking closer he noticed the center seizure screw was also loose. He tightened down the seizure screw and the 435 MHz went away

• completely. He them tightened the

back of the tap and the 729 MHz leak dropped as well. This location was a good example of multiple leaks existing at different frequencies, each caused by a different problem.

< HOME

QAM Snare

System Demo Location #3

< HOME

Drive Routes

From QAM Snare admin the drive routes and found leaks can be seen. For it’s mapping software QAM Snare uses OpenStreetMap.org which is open source. Arcom can also incorporated node boundaries.

< HOME

List of found leaks comparing QAM Snare and XYZ leakage detector

From the top 12 leaks QAM Snare found only three were picked up by the XYZ. This comparison is not intended to show the weakness in a competitors product but rather show the value in measuring leakage at the higher frequency. When actual leaks are found this validates the measured leaks.

Address QAM Snare (555 MHz) XYZ (112.7 MHz) 314 W Cottage ST 501 uV/m No 655 N Johnston Ave 355 uV/m 153 uV/m 1005 N Francis Ave 200 uV/m No 191 S Stadium Drive 178 uV/m No 1238 E 14th St. 141 uV/m No 1157 N Johnston Ave. 126 uV/m 50 uV/m 1147 N Francis Ave. 100 uV/m No 1972 Arlington St. 89 uV/m No 2376 E Woodland Dr. 79 uV/m No 1332 E 18th St 71 uV/m No 504 Short St. 71 uV/m No 1526 Arlington 63 uV/m 36 uV/m

< HOME

Flag 8 – 501uV/m – 314 W Cottage St.

At Flag 8 we found a cracked hardline cable only visible from above with a bucket truck. The leak found by the XYZ was below 20uV/m and was not considered a large enough leak to be flagged.

< HOME

Flag 5 – 355uV/m – 655 N Johnston Ave.

We found an illegal connection at this location. QAM Snare found a 355uV/m leak while XYZ showed this as a 153uV/m leak. The QAM Snare isolator lead us to the leak quickly, peaking while we pointed the antenna directly at the tap with the illegal connection.

< HOME

Flag 13 – 200uV/m – 1157 N Johnston Ave.

At this location we found a combination of three leak problems. We found two leaks around from the amplifier and the tap located close to the home. One leak was reduced in strength by tightening the seizure screw coming out the amp. The gasket on the tap was the other problem. We replaced the face plate on the tap as well as a new gasket and the leak dropped by another 30 dB. We also found an unterminated drop cable on the right hand corner of the home. The isolator helped find all three problems. XYZ did not detect a leak at this location.

< HOME

Digital Leakage Detection

> Detects digital channels leaking from the network

• Find leaks quicker and with greater accuracy

compared to the status quo technology – use leakage tools not just for compliance but as a network maintenance tool

• Gain visibility to a widespread set of hardline

impairments where there was previously no visibility: high frequency leaks that are invisible to analog detection methods

• Find egress affecting LTE
• Find forward ingress at any frequency
• In an all digital network, no need to reserve

an analog channel for FCC compliance

Summary:

< HOME

Work Flow

• Automatically route leakage work orders to technicians
• Assign work orders based on leak frequency and technician level
• High frequency leaks go to hardline maintenance
• Mid frequency distribution cable issues, loose face plates, splitters

etc..

• Low frequency leaks go to installers
• Prioritize high frequency work orders by proximity to cell towers
• Immediate notification of high level leak over programmable threshold
• Route work orders by hub or node groups
• Route work orders in proximity groups
• Route work orders by technician home address

< HOME

Work Flow – Impairment Resolution

7 options for closing out work orders

• QS Manager software
• Tech laptop and Webview
• On the QS Navigator
• Smartphone
• Paper work order
• Emailed work order
• Raw data export to Remedy or Unified

< HOME

QAM Snare Differentiators

1.

QAM Snare has no need to inject a carrier. So no concerns to an injected carrier frequency drift or level stability, and no concerns of interference with adjacent QAMs.

2.

Frequency agile from 133 to 885MHz. Operator can use any broadcast QAM and can change detection frequencies with a couple pushes of a button.

3.

Because we utilize time delay we are able to implement an advanced TDOA location algorithm. The benefit is high accuracy of the location of the leak allowing less time

4.

QAM Snare is impervious to multipath – a huge issue and time saver in the final detection step, again significantly reducing troubleshooting time.

5.

No false alarms. On some analog systems, up to 30% of alarms may be bogus – a big waste of resources. Eliminate “leak not found” from your terminology.

6.

No low vehicle speed limits for detection – and no doppler issues. Competitors limit is 30MPH.

7.

QAM Snare will work with any channel bandwidth – so it is fully compatible with any future downstream channel bonding or OFDM modulation.

8.

Integrated real time leak database.

9.

Compatible with and able to be used for flyovers.

< HOME

Thank you

Kendall Robinson Regional Account Director 503-730-6483

Email: robinson.kendall@arcomlabs.com Website: www.arcomdigital.com