IN THIS ISSUE
June/July 2006
Vol 6 Issue 2

Feature Article
Using iQ.clearXG for AWS Transitional Sharing and Incumbent Relocation

Case Corner
Electrical Utility Automatic Meter Reading Systems
and Earth Stations - An RF Interference Case Study

Contact us

Archives

Text only /
Printer friendly

Unsubscribe

 Update my
subscriber info

 Forward to
a friend

» Special Notice to Operators of 4 GHz Receive Earth Stations - click here «

by Peter Young
Principal Engineer, Comsearch

Using iQ·clear^XG for AWS Transitional Sharing
and Incumbent Relocation

Introduction
The reallocation of the 1.7 and 2.1 GHz microwave bands for use by Advanced Wireless Services (AWS) raises many issues for both new licensees and incumbents. In the March 2006 issue of the WirelessPulse, the feature article discussed several facets of the AWS allocation and issues surrounding the incumbents in the affected band. A key issue is that microwave incumbents will remain in the bands for some time after AWS deployment has begun and systems are activated. This will give rise to a period of Transitional Sharing where AWS systems will share spectrum with incumbents before they are entirely relocated to new bands.

Once the auctions are completed and licenses are granted, AWS operators are obligated to protect incumbents against interference from AWS operations. To address this, Comsearch has developed iQ·clearXG, a spectrum sharing analysis tool used to predict interference between AWS and incumbent systems. This paper will explore how transitional sharing can be accomplished to facilitate the rapid deployment of AWS systems while protecting incumbents from interference.

Transitional Sharing
AWS licensees will be highly motivated to recoup their investment by putting their spectrum to use as quickly as possible. In order to accomplish this, it will be necessary to evaluate the incumbent interference environment for immediate spectrum sharing opportunities and to identify and prioritize incumbent systems for eventual relocation. Transitional sharing will be possible to varying degrees which will allow AWS licensees to implement early phases of their system before all incumbents are relocated.

Incumbents in the AWS bands include Federal Government systems at 1.7 GHz and private/common carrier microwave systems and Broadband Radio Service (BRS) systems at 2.1 GHz. The issues faced by AWS operators are similar to those faced by PCS licensees in the 1.9 GHz band where new PCS systems were allocated spectrum occupied by private microwave systems. By conducting interference analyses and coordinating deployment proposals with incumbents, PCS licensees were able to deploy systems prior to full scale incumbent relocation, essentially sharing the band for some interim period of time.

Similar spectrum sharing solutions will also be necessary to ensure rapid deployment of AWS systems in the 1.7 and 2.1 GHz bands. However, it is important to recognize that there are differences between the PCS and AWS relocation efforts.

Figures 1 and 2 below depict the interference scenarios for PCS and AWS respectively. As shown in Figure 1, because the PCS allocation occupied a single frequency band and the channel blocks corresponded with the incumbent channel plans, the interference calculations were relatively straightforward. In addition, because the interference to and from the PCS base station and mobiles impacted both ends of the same link, resolving interference cases into incumbents generally eliminated the interference potential into the PCS systems.

Figure 1: PCS Interference Scenario

With AWS, however, the incumbent interference scenario is quite different. The complications introduced by the AWS allocation being in two bands means the interference must be calculated separately for both the base stations and mobiles. Interference from a mobile into a 1.7 GHz microwave receiver follows a different interference path than interference from the 1.7 GHz microwave transmitter into the base station. Likewise, interference from a base station into a 2.1 GHz microwave receiver follows a different interference path than that from the 2.1 GHz microwave transmitter into the mobile. Figure 2 illustrates that interference analyses must be performed for both the base stations and the mobiles.

Figure 2: AWS Interference Scenario

Another significant difference between the PCS and AWS relocation is the number of fixed links that are licensed on a secondary basis.

Coordination and deployment of new 1.9 GHz fixed links ceased shortly after the FCC issued the PCS reallocation order. This was due in part to the timing of the PCS auctions and in part to the designation of all links as secondary after a given timeframe. The FCC reallocated the 2.1 GHz spectrum to Emerging Technologies in the same PCS reallocation order. Since the 2.1 GHz spectrum didn’t have an immediate auction in process, many operators continued to deploy fixed links in this band on a secondary basis. Therefore, there are a significant number of secondary microwave links in the 2.1 GHz portion of the AWS spectrum. While licensees of these secondary links will be responsible for the cost of relocation, they should be aware of their rights to use the spectrum:

• The secondary licensee can continue to operate until the secondary link is determined to cause potential interference into the AWS licensees proposed operations, at which point they have to cease operations.
• The AWS licensee is expected to provide at least 30 days notice to the microwave licensee before beginning operation.

Methodologies

Fixed Microwave Links
The majority of incumbent systems in the 1.7 and 2.1 GHz bands are fixed microwave links. The FCC, in its AWS Service Rules Report and Order (WT-Docket No. 02-353), states that AWS licensees must follow FCC Rule Part 24.237 when evaluating the interference potential between AWS and incumbent microwave systems¹. Specifically, this rule includes the requirement that, unless AWS and fixed microwave licensees agree on an alternative method, TIA Technical Service Bulletin 10-F: "Interference Criteria for Microwave Systems" (Bulletin 10-F) must be used as the guideline for determining the interference potential between AWS and incumbent microwave systems. In addition, the FCC states that they "would accept the procedures developed by any 'recognized authority' in determining appropriate interference."²

Bulletin 10-F is based upon work done in TIA Committee TR-14.11, "Interference Criteria for Microwave Systems in the Safety and Special Radio Services". It identifies key considerations for sharing spectrum between fixed and mobile services including: coordination distance, methods to aggregate mobiles, multiple propagation models, interference criteria, and coordination distances. It was used extensively and successfully for PCS sharing with Private Microwave at 1.9 GHz and can be applied to transitional sharing for AWS.

Deploying AWS Networks
Using Comsearch’s iQ·clearXG analysis software, AWS operators can accurately calculate interference potential between cell-based networks and incumbent fixed microwave operations. Such an analysis is beneficial in all phases of the AWS operators business, from auction planning and bid prioritization to AWS deployment to post-sunset coordination. For purposes of this paper we discuss in detail the impact of this analysis on a typical AWS deployment.

Analysis
Comsearch took a sample AWS system consisting of 87 sites with 169 sectors using UMTS technology in Pittsburgh, PA. We conducted a detailed analysis of AWS Blocks A, B and C for comparison purposes, as shown in Table 1, below.

Table 1: Pittsburgh CMA Result Summary

There were anywhere from 571 to 917 incumbent links (depending on the block analyzed) within the coordination distance of this system and within the AWS spectrum that were considered in the analysis. As indicated by Figure 3 below, the results showed many areas (colored in green) in the Pittsburgh market where service can be deployed without incumbent relocation. Additionally, in order to operate on all channels in all of the cells, only a few links out of the total links analyzed would need to be relocated as shown in Table 1.

Figure 3: Pittsburgh CMA Results for Blocks A, B, and C

Once the link status is confirmed as primary, the AWS operator would then contact the incumbent to initiate relocation negotiations and start the mandatory negotiation period. If the link is licensed on a secondary basis, the operator will need to notify the incumbent in order to give them the required 30 day notice prior to operation.

Prior Coordination
FCC rules require AWS licensees to provide coordination notification to incumbents prior to system deployment. This involves sending a Prior Coordination Notice (PCN) containing specific information about their proposed cell sites to all potentially affected incumbents within a specified distance defined as the coordination area.

For the 2.1 GHz band, this is a relatively straight-forward process. Once the PCN is sent to the 2.1 GHz incumbents, the incumbent licensees are required to review and respond to the PCN if they believe interference will occur. If the incumbent believes that there will be interference into their system, they will need to respond to the AWS operator with documentation of the specific interference calculation within 30 days.

For the 1.7 GHz band, the process is anticipated to be much more complex due to the different types of incumbent systems involved (fixed, mobile and classified) and coordinating with Federal Government agencies not familiar with the analysis and coordination procedures. In an effort to clarify the interaction between AWS licensees and government agencies, the FCC issued a Public Notice that required all AWS licensees to coordinate their frequency use with government incumbents and outlined general coordination procedures. Most notable, AWS licensees must send interference analysis results to a designated agency contact for review. The agency has 60 days from acknowledgement of receipt to review the interference analysis. At the end of the 60 days, if the agency does not object, the AWS licensee may commence operations.

Once the notice periods are complete and all response letters with reported potential interference cases have been resolved, the AWS licensee can turn up their system.

Conclusion
Transitional sharing between AWS and incumbent systems in the 1.7 and 2.1 GHz bands will be possible to varying degrees that will permit a certain level of AWS deployment before full scale incumbent relocation occurs. The sharing and relocation procedures developed and implemented for the PCS 1.9 GHz band proved to be highly successful and utilizing iQ·clearXG, Comsearch looks to replicate similar processes and procedures for AWS. The ability to analyze the sharing potential and coordinate transitional solutions will be especially critical for links in the 1.7 GHz bands, where the relocation timeframes are specified and less likely to be negotiated.

For more information on Comsearch’s AWS Spectrum Sharing and Microwave Relocation Services, contact us at customersupport@comsearch.com or (800) 318-1234.

¹Service Rules for Advanced Wireless Services in the 1.7 GHz and 2.1 GHz Bands, WT Docket No. 02.353, Report and Order, Released November 25, 2003. 114.
²Id

by Steve Sackitt
Senior Field Engineer, Comsearch

Electrical Utility Automatic Meter Reading Systems
and C-band Satellite Earth Stations

— An RF Interference Case Study —

Utility companies are starting to retrofit their electrical meters with new digital Automatic Meter Reading (AMR) capability. This allows the power companies to reduce the labor costs by remotely monitoring the meters, get a daily usage reading, and monitor the performance of their system network. A recent article in The Washington Post describes how a local power company plans to deploy AMR technology to read over 2000 electric meters in Washington, DC (click here to read article). These new meters can utilize practically any wireless technology including BPL, TCP/IP, land-line telephones, and existing VHF systems. However, some of these technologies can cause problems into other users of the spectrum. This paper will describe a real-world example of how that can occur, and will give some possible mitigation steps for the conditions created.

The conflict was encountered at an existing earth station teleport facility. The initial complaint received was that daily, around 12:00 AM, a 7.4-meter C-Band Earth Station was experiencing a signal drop-out (SD) event that lasted approximately thirty seconds. Another 10-meter C-Band earth station at the teleport was also experiencing this same problem, but it was occurring at around 9:00 AM. These SD events were something new at the teleport, and had not been witnessed before. At the time of the reported complaint, they had been going on for a couple of weeks with daily regularity. The investigation by Comsearch revealed that the cause of the SD was from the electric utility company’s use of cellular transmissions for their AMR systems. In this particular case, the power company opted to utilize PCS TDMA and cellular CDMA technologies. These meters are polled daily at roughly the same time every day.

The power meter output monitors are designed to transmit at an RF power level of +23 dBm. The PCS AMR meters, which utilize TDMA, were terminated into a 1/4 wave dipole antenna. The power meters that utilized cellular CDMA were terminated into a +3 dBi loaded stub antenna. Photograph 1 shows an example of the TDMA style AMR system and photographs 2 and 3 show examples of the CDMA style AMR system. The EIRP of these systems is quite high and it was determined by measurements that the second harmonic of the PCS TDMA and the fifth harmonic of the cellular CDMA fell within the pass band of a C-Band Earth Station. These transmitted signals occurred when the meters were polled by the electric company for data dumps. This resulted in saturation of the earth stations low noise block (LNB’s) amplifiers, causing the satellite SD.

At this teleport, the location of these AMR’s in relation to the azimuth of the satellite antennas was the key in isolating the SD event. The PCS TDMA AMR transmitter was situated at the exact azimuth of the 10-meter earth station antenna at a distance of only 15 feet . The cellular CDMA AMR transmitter was situated at the exact azimuth of the 7.4-meter earth station antenna at a distance of 100 yards. These meters were manually polled by the power company to verify that the SD was correlated to the transmission from the AMR’s.

Looking forward, this may be an issue that will be faced by other C-Band earth station operators. Earth station managers should be made aware that this is a distinct interference threat. It should also be noted that the power companies are offering reduced rates if their industrial customers accept this AMR installation at their facility.

To avoid the problems uncovered in this study, transmissions from the AMR monitors should never be allowed on-azimuth with the earth station antennas. In addition, their transmission line should be fitted with harmonic filtering that will reduce the emissions in the pass band of the earth stations reception band by at least 40 dB.

 

Special Notice to Operators of 4 GHz Receive Earth Stations A recent FCC rulemaking (ET Docket 04-151) opening up the 3650 – 3700 MHz band to unlicensed broadband devices may put your 4 GHz receive earth stations at an increased risk for harmful interference. In the Order, the FCC outlined a new hybrid approach to licensing systems in the 3650 – 3700 MHz band. Virtually anyone can apply for a nationwide non-exclusive license with the requirement to register base stations in ULS prior to system deployment. Parties registering systems in ULS are required to avoid locating a fixed station within 150 km of a co-channel extended C-band satellite receive site; however, there is no similar protection zone for adjacent band satellite receive sites. The Satellite Industry Association (SIA) recently filed comments in the FCC proceeding identifying two sources of potential interference from operations in the newly allocated band that may impact adjacent C-band earth stations. The first type of potential interference involves Out of Band Emissions (OOBE) of the new wireless broadband devices that spill over into the adjacent fixed satellite band. According to the SIA, the current OOBE limit of -43 dBW/MHz contained in the Order is insufficient. They calculate that a wireless device that complies with the Commission’s OOBE requirements could interfere with an earth station at a distance of 1,000 meters. To mitigate this problem, the SIA has requested a more stringent limit of -71.25 dBW/MHz. The second type of interference (and the most problematic) involves the in-band emissions of the broadband devices that are picked up by the sensitive earth station receivers. Satellite earth stations typically operate with very little margin between desired and undesired signals due to the relatively low signal levels received from the satellite. Thus, because the level of the undesired signal introduced by the terrestrial broadband systems is much higher than the desired satellite signal level, there is a potential for the wireless broadband signal to saturate the FSS receiver LNB. According to the SIA’s calculations, LNB saturation can occur from wireless broadband devices operating at distances of thousands of meters from the earth station. They note that the earth station LNBs typically do not provide any selectivity to signals in the 3650-3700 MHz segment. Interference filters offer some relief but would not have much effect on signals immediately below 3700 MHz. The interference issues become even more problematic if your 4 GHz earth station is unlicensed. Unlike a licensed system that is afforded certain interference protection rights, an unlicensed system enjoys none of the same privileges. If you are operating an unlicensed 4 GHz receive earth station and are concerned about the increased potential for interference, call us for information regarding FCC licensing procedures.

MICROWAVE

FCC Modifies Advanced Wireless Services Auction Schedule, Moves Start Date to August 9, 2006 - The FCC released a Public Notice that revised the schedule and filing requirements for the FCC's upcoming first auction of spectrum licenses for Advanced Wireless Services (AWS).  (Dkt No 06-30, AUC-06-66-C)  DOC-265462A1.pdf  DOC-265462A2.pdf  FCC-06-71A1.pdf  FCC-06-71A2.pdf

Coordination Procedures for the 1710-1755 MHz Band - The FCC and NTIA outline coordination procedures in the 1710-1755 MHz band (Dkt No 02-353, FCC No. 06-50).  FCC-06-50A1.pdf

FCC Modifies Rules for 2496-2690 MHz Broadband Radio Service (BRS)/Educational Broadband Service (EBS) Spectrum Band To Facilitate Wireless Broadband Access - The FCC adopted an Order that continues the FCC's efforts to transform its rules and policies governing the 2496-2690 MHz BRS and EBS band.  (Dkt No 97-217, 00-230, 00-258, 02-364, FCC No 06-46) DOC-264897A1.pdf  DOC-264897A2.pdf  DOC-264897A3.pdf  DOC-264897A4.pdf  FCC-06-46A1.pdf  FCC-06-46A2.pdf  FCC-06-46A3.pdf  FCC-06-46A4.pdf

Auction Of Air-Ground Spectrum Licenses Concludes - The FCC's auction of two nationwide Air-Ground spectrum licenses in the 800 MHz band ended on June 2, 2006, raising total net bids of $38.3 million. (DA No 06-1197, AUC-06-65-I) Winners announced. DOC-265757A1.pdf  DA-06-1197A1.pdf  DA-06-1197A2.pdf  DA-06-1197A3.pdf  DA-06-1197A4.pdf

FCC Seeks Public Comment On Creation Of A Spectrum Sharing Innovation Test-Bed – (Dkt No 06-89, FCC No. 06-77)  FCC-06-77A1.pdf  FCC-06-77A2.pdf  FCC-06-77A3.pdf  FCC-06-77A4.pdf

Law Enforcement Act and Broadband Access and Services - The FCC adopts Order to enable law enforcement to access certain Broadband and VoIP providers. (Dkt No 04-295, FCC No. 06-56) FCC-06-56A1.pdf  FCC-06-56A2.pdf  FCC-06-56A3.pdf  FCC-06-56A4.pdf  FCC-06-56A5.pdf 

FCC to Establish a Public Safety and Homeland Security Bureau - The Commission voted unanimously to establish a "Public Safety and Homeland Security Bureau.”  DOC-264395A1.pdf DOC-264395A2.pdf DOC-264395A3.pdf DOC-264395A4.pdf  DOC-264395A5.pdf DOC-264395A6.pdf

Remarks of Jonathan S. Adelstein, Commissioner, Federal Communications Commission -  National Spectrum Managers Association, Spectrum Management 2006, Arlington, Virginia, May 16, 2006.  DOC-265394A1.pdf

SATELLITE

FCC Announces Mandatory Electronic Filings Related to International Telecommunications Services
The International Bureau announced that beginning June 12, 2006, applications and other filings related to international telecommunications services must be filed electronically via the International Bureau Filing System (IBFS), in accordance with the rules adopted in the Commission’s Mandatory Electronic Filing Report and Order. Paper versions of these applications and filings will not be accepted as of that date and will be returned to the applicant without being processed, unless a waiver is approved by the Commission.

On May 11, 2005, the Commission adopted rules in its Mandatory Electronic Filing Report and Order that require applicants to file electronically applications and other filings related to international telecommunications services. The rules also require filers to submit such applications and other filings via the International Bureau Filing System (IBFS). These rules apply to the applications and filings associated with: section 214 authorizations; submarine cable landing licenses; accounting rate changes; assignment of data network identification codes; foreign carrier notifications; recognized operating agency status; and assignment of an international signaling point code. These rules became effective on April 12, 2006.

The FCC International Bureau Provides Guidance Concerning the Relocation of Earth Station Remote Control Points

Licensees operating transmitting earth stations in the United States are subject to Section 25.271 of the Commission’s rules, 47 C.F.R. § 25.271, which contains provisions that require earth station operators to maintain control of operations by having a trained operator at the earth station site, or by remotely controlling operations. Section 25.271(c)(5) of the Commission’s rules, 47 C.F.R. § 25.271(c)(5), requires that International VSAT operators must provide a control point within the United States, or maintain a point of contact within the United States available 24 hours a day, 7 days a week, with the ability to shut down any earth station within the VSAT network immediately upon notification of harmful interference. Further, the licenses for all earth stations operated by remote control list the remote control point, and this information is considered a material term of the license.

This rule, which permits licensees to make changes to their authorized earth stations without obtaining prior Commission authorization, is intended to apply only to the equipment specified on the license and does not apply to changes in remote control points. Therefore, where a licensee considers a change in the Earth station’s remote control point, including any relocation of the remote control point to a location outside the United States, the licensee must seek prior authorization under Section 25.117 of the Commission’s rules. The International Bureau will place properly filed modification applications for changes in earth station remote control points on public notice.

US Justice Department Closes Antitrust Investigation on Intelsat PaAmSat Merger
The US Justice Department has closed its antitrust investigation on Intelsat's proposed merger with PanAmSat, saying it is not seeking any conditions on the transaction and is not otherwise commenting on it. The proposed merger, however, remains under review by the US FCC. Intelsat and PanAmSat announced their merger agreement on August 29, 2005. Under the agreement, Intelsat will acquire PanAmSat for $25 per share in cash, or $3.2 billion.

Justice Department Green Lights SES Global's Acquisition of New Skies
The U.S. Department of Justice has completed its review of SES Global's acquisition of New Skies Satellites, effectively giving permission for the deal to go through. The acquisition was announced on December 14, 2005. The deal still has to receive the blessing of the FCC and Germany's Federal Cartel Office to proceed, plus the backing of New Skies' shareholders. New Skies expects its acquisition by SES Global to close in the second quarter. The deal will create the world's second largest Fixed Satellite Services operator behind a combined Intelsat-Panamsat.

1.7 GHz and 2.1 GHz AWS AuctionPlanner™ available From Comsearch
On August 9, 2006, the FCC will auction the spectrum in the 1.7 GHz and 2.1 GHz AWS bands. Comsearch has developed an AuctionPlanner product to provide a complete spectrum analysis for bidders in an easy-to-use format. Comsearch will provide statistical data using our proprietary databases combined with other datasets as necessary and available. Contact us at 800-318-1234 or customersupport@comsearch.com for more information.

Comsearch offers AWS Spectrum Sharing and Incumbent Relocation Services
Comsearch provides comprehensive relocation solutions to meet the engineering and deployment requirements imposed on AWS licensees. We combine our specialized services, highly-accurate databases, and program management abilities to identify interference issues and facilitate the relocation negotiations between AWS licensees and incumbent operators. Learn more about our services.

Bridgewave and Loea sign on with Comsearch for Link Registrations
in the 71-95 GHz Spectrum
Bridgewave (www.bridgewave.com) and Loea (www.loeacom.com) chose Comsearch as their database manager for quick and easy registration of their links operating in the 70, 80, and 90 GHz bands, ensuring interference-free operation with commercial and Federal Government users. For more information about these bands, go to Comsearch's link registration website, www.gigabitlink.com.

BridgeWave Communications designs and manufactures gigabit wireless broadband solutions that are enabled by BridgeWave-developed transceiver and modem technologies. BridgeWave's solutions utilize high-frequency radio spectrum in the 60-90GHz range, recently allocated by the FCC, enabling multi-gigabit per second wireless connectivity.

Loea Corporation is a world class designer and manufacturer of ultra broadband fixed wireless telecommunication equipment operating in the upper millimeter-wave spectrum from 71.0-86.0GHz.

Mark Gibson, Senior Director, Business Development for Comsearch presented "Taking Control of your Wireless Spectrum" at the Association for the Advancement of Medical Instrumentation (AAMI) 2006 Conference & Expo in Washington, DC on June 25.

Not subscribed?

  
If you have been forwarded WirelessPulse by a friend or colleague and wish to subscribe yourself then click below and enter your details.

CLICK HERE TO SUBSCRIBE