Digital Leakage Today

Transcription

1 Digital Leakage Today Analog and Digital Leakage LTE interference Kendall Robinson Regional Account Director Arcom Digital

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

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4 Traditional Signal Leakage Today Most legacy leakage systems are in the aeronautical band from 108 to 137MHz A common frequency is MHz (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

5 Signal Leakage Regulations Signal leakage regulations in Part 76 of the FCC s Rules. The following table, taken from (a)(12), states the maximum allowable signal leakage field strengths across various frequency ranges: Frequencies Signal leakage limit in microvolt per meter (uv/m) Distance in feet (f) Distance in meters (m) Less than 15 ~ MHz 54MHz to 20 ~ MHz Over 216 MHz 15 ~100 30

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7 Signal Leakage Regulations Distance at 10 feet is 20uV/m larger Frequencies Signal leakage limit in microvolt per meter (uv/m) Distance in feet (f) Distance in meters (m) Over 216 MHz 15 ~ Over 216 MHz 150 ~10 3

8 LTE Types of LTE Towers The Monopole Tower is a single tube tower. It typically stands between ft. with antennas mounted on the exterior of the tower. Its primary use is telephony.

9 The Lattice Tower The Lattice Tower is sometimes referred to as "self-support or SST because it is free-standing. It stands ft. tall with a triangular base and three-four sides. It is typically used for telephony. The Eiffel Tower is a lattice tower.

10 The Guyed Tower The Guyed Tower is basically a straight rod supported by wires that attach to the ground as support. It's cheapest to construct, especially at heights of 300 ft and beyond. Some guyed towers reach as high as 2,000 ft. Typical uses are: telephony, radio, television, and paging.

11 The Concealed Tower Concealed and Stealth Towers. Stealth towers are a particular brand of concealed towers. Another manufacture of concealed towers is Larson Camouflage. Concealed towers are deployed to satisfy zoning regulations, and can range in size to accommodate their surroundings. Opposite is one of the more interesting concealed towers, located at a church in California.

12 The Concealed Tower

13 The Concealed Tower

14 LTE Equipment An Antenna Array is a platform where tenants mount antennas, which signal transmission and reception to mobile devices within a specific area. The number of antennas (typically between 3-18) is based on several factors, including the number of tenants (wireless carriers); the type (voice or data) and volume of transmission; the technology being used (eg: CDMA, GSM, LTE, WiMAX) and the frequency of spectrum (in MgH) utilized.

15 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)

16 Orthogonal Frequency Division Multiplexing OFDM is a broadband multicarrier modulation method that offers 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 operation in the UHF and microwave spectrum.

17 What makes LTE different to Traditional Cell technology? LTE in the USA is in the 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.

18 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 MHz, UL MHz) for Verizon Band 17 (DL MHz, UL MHz) for AT&T.

19 US FCC 700MHz LTE Bands

20 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 ( 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.

21 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..

22 LTE Ingress Interference LTE interfering with the CATV system LTE Inference - You Tube Youtube Link to LTE Interference

23 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.

24 What ATT and Verizon are finding They find Leaking CATV devices using a portable RF analyzer and directional antennas. These units are very expensive. Est: $42K each

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26 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. Courtesy Verizon

27 Courtesy Verizon

28 Courtesy Verizon

29 Courtesy Verizon

30 Courtesy Verizon

31 Courtesy Verizon

32 Courtesy Verizon

33 Courtesy Verizon

34 Courtesy Verizon

35 What CATV operators are finding causes of high frequency leakage 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

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

37 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

38 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

39 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

40 Advanced location methodology Because of the employed correlation detection process and inherent time delay output we have a unique opportunity 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. Time difference of arrival (TDOA) hyperbolic location QAM Snare is impervious to multipath/standing wave type issues that are prevalent with analog detectors thereby making the final isolation process significantly easier.

41 Simultaneous three channel detection QAM Snare is designed to detect and record leakage from any three digital channels simultaneously Typical choices are Aeronautical ( MHz), Mid-band (550MHz) and LTE (750MHz) 567MHz 579MHz 729MHz

42 Understanding a Leak Is it the same level at low and high frequencies? 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?

43 Lack of correlation of leaks from one band to another Low Frequency only Low and High Frequency High Frequency only

44 Combined leaks on one graph

45 Leaks in different frequency bands are due to different sets of problems Aeronautical band below 200MHz 96% drops and soft cable issues 300Mhz to 500MHz 40% drops-60% small cable issues and loose devices 600 to 900MHz 90% Hard line issues and 10% other and LTE

46 3 Channel Detection Red Flags are leaks >100uV/m, Yellow uV/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.

47 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.

48 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.

49 Dramatic Differences in Frequency Response 600 MHz Vs 777MHz (Upper LTE Band) From another recent test, we captured 140 leaks over 4 days. The results show dramatic differences between these two frequencies.

50 The technology Simultaneously detect Leaks and record LTE RSSI (Received Signal Strength Indicator) Given the average of one LTE leak per plant mile, it is unrealistic to attempt to repair all leaks. Leak magnitude on its own is not the only consideration that a leak will negatively affect an LTE base station (BTS), because it doesn t take BTS proximity into account. The criterion as to how to prioritize repair is a big issue that has significant impact on ongoing operating costs. An ideal solution has been implemented within QAM Snare measure and record LTE signal strength, simultaneous to the leak detection efforts!

51 The technology LTE Signal Strength coupled with leak detection QAM Snare tuner is agile and shares the time making multiple leaks and making LTE signal strength measurements. Tunes and scans through all the LTE downlink frequencies and record the maximum received signal strength. All within one second.

52 LTE signal strength The technology An example below is looking at a variance in LTE received signal level over a 50 minute drive out. At the locations with low signal level, even egress from a very large leak will have no effect on the BTS performance and should therefore have a low priority of repair conversely, even smaller level leaks at locations with large LTE signal strength, that are in close proximity to a BTS, should have a high priority for repair.

53 Use LTE RSSI as a driver of repair The prioritization technology Along with leak level, LTE RSSI is recorded in the database in real time. Sort by LTE RSSI over a defined threshold, display only those leaks on map, generate work orders using LTE RSSI as a criterion.

54 Benefits of frequency agile detection Better coverage and protection 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 Right technician for the area of focus Prioritize leaks with highest LTE signal strength

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56 Implementation options: Navigator and Isolator used in companion to find and fix leaks: QAM Snare Navigator: QAM Snare Isolator: 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)

57 Implementation options: Monitor used for passive detection repair later: QAM Snare Monitor: Monitor: Permanently mounted in vehicle Continuously reports leaks data to Headend Signal processor Designed to detect and locate leaks with no user involvement

58 Implementation options: QAM Snare Web Client QAM Snare Isolator: 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 Monitor:

59 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. QAM samples and timing over ISM transceiver chipset

60 QAM Snare System Demo Location #1

61 Flag uV/m at 711MHz 5868 Beachwalk Dr At Flag 89 we found a cracked tap housing that subsequently broke off. No analog leak was found.

62 Flag uV/m at 711MHz 5876 Goulagong Dr Burnt out tap with suck out around 470MHz..

63 Flag uV/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.

64 Flag uV/m at 711MHz 5902 Woodstock Ct Radial crack in the feeder cable.

65 Flag uV/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.

66 Flag uV/m 749 Fiona Ln Flag 52 2 nd Tap 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.

67 QAM Snare System Demo Location #2

68 Two Leaks at one location Flag 7 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. 729MHz 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.

69 Three Leaks at one location Flag 4 729MHz 435MHz 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.

70 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.

71 QAM Snare System Demo Location #3

72 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.

73 List of found leaks comparing QAM Snare and XYZ leakage detector 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 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.

74 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.

75 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.

76 Flag uV/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.

77 Summary: 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

78 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

79 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 ed work order Raw data export to Remedy or Unified

80 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.

81 Thank you Kendall Robinson Regional Account Director Website: