Subject: [NEXTEL-1] Strong Signals - FCC News

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Date: Tue, 02 Sep 2003 02:42:46 -0400

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FCC News

Industry Comments To Nextel Proposal

Posted on 06/20/2002 09:16 EDT

Thanks to a posting by Marcel on SCAN-L, we can read some of the 234
comments which have been filed to date regarding the FCC's Notice of
Proposed Rule Making (NPRM) to solve the interference problems across
the US to various public safety agencies.

To see the comments, use the first link below and when the search
engine page appears, type '02-55' in the "1. Proceeding" field and
then click on the "Retrieve Document list" button.

The comments are many and varied coming from states, counties,
businesses, radio manufacturers and, of course, cellular providers
which are under intense scrutiny with regard to this issue.

After browsing some of the comments, I decided to post here some of
the basic arguments from the various commentors. Keep in mind that
these are simply comments taken out of context which were part of
much larger documents. I have tried my best to preserve the intent of
the original commentor in the synopsis that follow:

City of Newport News

The close channel spacing and the noise limited cellular style design has led
to the interference problems that are being seen nationally today. The FFC
has, in the past, required new service providers that have caused interference
to resolve the interference or cease operations. Therefore, I do not believe
the burden and cost of reloaction should be placed on the Public Safety
community and ultimately the public. Instead, the burden and cost should be
born by Nextel Communications.

State of Hawaii

The State of Hawaii...considers that it would be against the public interest
to adopt any plan to reconfigure the 800 MHz frequency band that would cause
the rechannelization of existing public safety radio systems.

...

A consideration of the cost, complexity, and liability associated with any
relocation of public safety communications systems indicates that the most
prudent option is for existing public safety systems not to move.

...

Immediate steps must be taken to eliminate interference to public safety
communications systems that is now occurring.

They then go on to propose that next generation cellular systems be placed in
the 700 MHz band (instead of public safety users), current cellular bands
(824-849, 869-894) will slowly be emptied and filled with what had been planned
as the 700 MHz digital public safety band.

Kenwood Communications Corp

Kenwood is troubled by the Commission's hrried approach to a comprehensive
solution to PS interference at 800 MHz.

...

There should be a technical inquiry to determine the principal cause of the
interference. Kenwood believes that the study may reveal that the principal
contributor to the intereference is cellular architecture SMR systems in the
800 MHz band. If that is the case, it is reasonabble and consisten with the
precedent to impose the burden of interference resolution on those licenses,
rather than burdening the entire licensee base.

...

Nextel argues, for example, that it is unfairly labelled as the principal
contributor to the increase in PS interference, when in fact the causes and
contributors are several, including conventional cellular systems and others.

...

The Notice states that with the proliferation of CMRS antennas in urban
areas, for example, there are increased incidents of mobile and portable PS
transceivers in close proximity to the CMRS base trnasmitters. The PS devices,
attempting to receive weak signals, are going to be subject to incidents of
interference from the stronger CMRS base antennas.

...

There is reason to believe that elimination of PS interference created by
Nextel operation would solve a substantial portion of the PS interference
problem at 800 MHz. If that is the case, the bulk of the interference
resolution burden is properly placed on Nextel. Indeed, Nextel has proven that
it is willing to address PS interference problems on a case-by-case basis, and
is in a position to reduce interference.

...

Fairness dictates that the last in time to arrive at the site who is a
contributor to the EMC problem is the one obligated to resolve it and to bear
the burden and expense of doing so.

...

Kenwood suggests that the Comission has an insufficient basis to conclude that
any large-scale restructuring of the 800 MHz band is necessary to address
interference to PS in this band.

Aeronautical Radio

Aeronautical Radio, part of the Private Wireless Coalition (along with the
Association of American Railroads and other industrial organizations), supports
the Nextel proposal for the most part by adoptin a long-term move of PS to 700
MHz and in the short term, advises addressing interference problems on a
case-by-case basis.

State of Florida

Florida agrees in general with the Commission's assessment of the scope and
causes of CMRS interference to public safety systems. Our direct experience of
interference are completely related to situations involving high power CMRS
stations...

...

Florida questions Nextel's assertion that intermodulation is the primary
interference mechanism, due exclusively to public safety receiver
characteristics. The "dead spot" cases examined within Florida's statewide
800 MHz system appear to be caused by receiver overload due to excessively
high sideband noise.

...

Florida maintains that all costs associated with the relocation of public
safety systems be fully reimbursed, including all identifiable and justified
engineering, legal, and administrative costs.

...

Florida contends that any and all parties contributing to the public safety
interference should share in the financial obligation to remove the
interference. This removes the ceiling imposed by Nextel's $500 million
limit, thereby creating an open-ended financial strategy.

...

Regardless of all other proposals in this NPRM, we strongly urge the Commission
to explore all possible options of reducing interfering CMRS signal levels
through out-of-band emission limits, reduction ofsignal level, increased
distances from public roads, and a decrease in use of the lower CMRS "A"
frequencies (or any combination), prior to any decision to proceed with band
restructuring.

AT&T Wireless Services

They opt for a short-term case-by-case fix and a long-term migration of PS to
700 MHz. They also place the interference blame on the PS radio manufacturers
who "have continued to design public safety handsets and networks for
'noise-limited' environments despite the fact that CMRS carriers in the 800
MHz band have long been deploying more efficient interference-limited systems."
They also contend that "many design considerations, such as improved filters
and low noise amplifiers with better third order intercept specifications,
which could have made the public safety handsets virtually immune to receiver
overload from CMRS carriers, were never implemented. While public safety
receivers must be able to pick up weak signals, there is no reason for them to
be devoid of the adequate filtering and other measures that would allow public
safety licensees to coexist successfully with other licensees."

...

"While CMRS out-of-band emissions specifications already are stringent,
Nextel's location in the interleaved band (854.75-861 MHz) directly next to
public safety services results in a greater likelihood of Nextel transmitters'
out-of-band emissions causing interference to public safety handsets than
cellular transmitters. ... Given these factors, it is clear that Nextel is the
primary cause of interference in the 800 MHz band."

M/A-COM, Inc.

The digital SMR industry and the public safety community have expended much
effort trying to resolve these cases of interference. The problem is that often
times identifying or replicating any incidence of interference is
time-consuming and inconsistent. Identifying the problem so that fixes can be
designed and implemented is often unique to a given situation and
any fixes identified for one incidence may or may not be applicable to any
other situation.

...

M/A-COM further believes that the Commission is correct in it belief that some
sort of realignment/reorganization of the 800 MHz band will be necessary to
craft a reasonable and timely solution to the public safety band interference
problem.

Cingular Wireless and ALLTEL Communications

As a preliminary matter, the Joint Commenters disagree with the Notice's
blanket characterization of "cellularized CMRS systems" as the cause of severe
interference to public safety communications.

...

...current evidence indicates that a significant majority of interference to
public safety users is caused by Nextel's ESMR operations.

...

As [APCO's] Project 39 [report] indicates, "ESMR sites operated by Nextel and
other ESMR operators seem to be the most commonly identified contributing
factor" to interference to public safety operations.

...

Receiver overload is the major cause of interference to public safety users
because public safety radios are designed to have a wide front end due to
the broad range of frequencies that have been allocated to public safety. As
the Commissions states in the Notice, "public safety receivers are often not
sufficiently selective to reject undesired signals."

...

In the case of public safety interference, the undesired intermodulation
products are produced inside the public safety receivers. As with receiver
overload, the wide front end design of the public safety radios, combined with
limitations of the low noise amplifier, are responsible for the generation of
the undesired intermodulation products.

...

In light of the foregoing, receiver overload can be primarily reduced by
deploying public safety receivers that are more discriminating in the signals
they pick up, and to a lesser extent through frequency and geographic distance
separation between public safety and commercial operations.

Cellular Telecommunications & Internet Association

CTIA does not, however, believe that the specific proposal Nextel developed is
the best approach to solving the interfernece problems being experienced in
that band. Accordingly, CTIA opposes Nextel's proposal because it fails to
fully remedy interference problems and it will not provide adequate long-term
solutions to resolve the problems being experienced in the 800 MHz band.

...

CTIA has determined, based upon significant input from its members' technical
representatives, that moving Public Safety to the 800 Mhz band, coupled with
improved Public Safety equipment, would be the best means of eliminating
interference.

...

As an immediate step to ameliorate the interference problems [in the short-term],
CTIA urges the Commission to build on existing efforts to address interference
incidents by organizing a specail task force of wireless carrer and Public
Safety representatives to ensure even better coordination of efforts to
eiminate interference to Public Safety users on a case-by-case basis.

Motorola

Motorola supports the use of the Class A specification for new public safety
and private wireless radios because the Class A specification appropriately
balanaces cost and performance tradeoffs in receiver design. Improved filtering
within a handheld receiver beyond this level is not currently viable as it
increases the size of the radio and drastically reduces the sensitivity to the
desired signal.

...

[Intermodulation] rejection performance coule be improved by increasing the
electrical current used by several stages of the radio receivers. However, this
would significantly increase current drain in the radios and thereby recude the
battery life of the product. Public safety radios are designed so that a single
battery will last an entire shift. Reducing battery life would require first
responders to carry an extra battery and would risk requiring battery
replacement at critical times.

Intel

In the absence of a specific fule, the Commission has relied on the principle
known as the "last in, fix it" to resolve interference disputes. Based on this
principle, it is clear that the Commission can require Nextel to remedy any
interference at its own cost.

...

In summary, Nextel is required by Commission rule and pocliy to remedy at its
own cost the interference that it is causing.

One Motorola document contained interesting details on "Wireless
Enabled Homeland Security" along with "Public Safety System Design
Considerations". Use the link below to see this PDF document.

LINK: FCC Filed Comments Search Engine

LINK: Motorola document - PDF

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