A Review of the Proposed Two-Way Wireless Cable Rules Changes October 2002: Technical Note 120A

Introduction

The Wireless Communications Association International, Inc., The National ITFS Association and the Catholic Television Network have presented a white paper to the FCC. That white paper is entitled “A Proposal for Revising the MDS and ITFS Regulatory Regime” and has been assigned FCC Docket Number DA 02-2732. Comments are due November 14, 2002 and reply comments are due November 21, 2002. That white paper may be downloaded here. This document is 94 pages long, and is provided as a PDF file.

The white paper details a new channel plan for the 2500 MHz “Wireless Cable” band and new operational and interference rules for that band as well as the 2150 MHz band used for MDS channels 1 and 2. The purpose of this LBA Technical Note is to present the reasons for the proposed changes and to summarize the proposed new channel plan.

The Reason

The licensees and operators in the so-called “Wireless Cable” band, which consists of the Multipoint Distribution Service ("MDS") and the Instructional Television Fixed Service (“ITFS”), were unable to use their spectrum efficiently. The original FCC Rules contemplated a one-way operation from a single high transmit antenna to many low receive antennas. Even when the FCC modified the rules to permit two-way data operations, these operations were laid over the existing framework. Due to interference constraints, many operators were unable to serve the desired portions of their service areas. The inability to deploy repeaters and “hub” stations where needed raised consumer costs to prohibitive levels. Information about the current state of the wireless cable industry may be found in LBA Technical Notes 106, 115, and 120.

The FCC recently transferred responsibility for regulating MMDS and ITFS operations to the Wireless Telecommunications Bureau. That Bureau desires to modify the FCC Rules to expedite the deployment of new technology and promote more efficient use of the spectrum, while at the same time protecting the operations of the existing users.

It should be noted that this discussion of a new channel plan relates only to the portion of the spectrum between 2500 MHz and 2690 MHz. The MDS 1, 2 and 2A channelization at 2150 MHz is unchanged by this proposal, although the service and interference rules changes will apply. Also see ET Docket 00-258.

Background

In the early 1960’s, television technology did not permit use of adjacent channels. Therefore, the new ITFS band was made up of groups of four channels that were interleaved with those of the next group. Although this meant that users of adjacent channels had to cooperate completely to avoid interference, it did permit use of all four channels. With the technology of the day, a set of four contiguous channels would only have permitted two to be used and two would have had to lie fallow. The current channel bandplan is discussed in LBA Technical Note 115 and is shown here as Tables IV and V.

The Commission recently modified the rules to permit two-way operations, as spelled out in LBA Technical Note 120. These changes were overlaid on the old television-based rules. They required prior approval for most changes in facility, and filing voluminous interference studies and supporting documentation for any change. In addition, the first-generation technology supported requires a line-of-sight path. Transmitter sites with good line-of-sight into large portions of the service area also had line-of-sight into neighboring areas, complicating the interference protection requirements. Because of system configurations, customer premises equipment (“CPE”) had to be professionally installed and not all customer sites could receive service. However, even so, a site visit was necessary to determine if service would be available. The large antennas at the customer’s end also created problems with local government zoning boards and homeowner’s association covenants, as well as making it more difficult to serve multi-tenant buildings.

This technology, which required high transmitter and receive sites with a line-of-sight path and high-powered return paths, is called “first generation” technology. It is analogous to traditional over-the-air television broadcasting, and is so regulated.

Manufacturers and foreign operators are now developing and deploying second-generation technology, and domestic operators see the need for and want the ability to deploy it as well. This “second-generation” technology does not require a line-of-sight path, and uses lower antenna heights and powers than the television-style systems contemplated in the FCC Rules. The equipment is also much smaller, and the combination of small size, low height and non-line-of-sight operation makes customer installation feasible. Customer installation provides cost savings and permits more rapid response to consumer demand. The existing model analogous to these “second-generation” systems is not broadcast television, but cellular telephone. The operators want the ability to deploy these systems with the flexibility inherent in the rules governing the cellular-type wireless communications systems. The need is to accommodate low power, fixed, portable and mobile customer facilities while still permitting some high-power, high-site facilities such as are still used by ITFS licensees.

In addition, because of concerns that consumer units might cause “brute force overload” interference to ITFS receive sites equipped with broadband downconverters, the Commission in the MDS/ITFS Two-Way Report and Order required the professional installation of equipment at consumers’ locations, mandated advance notice to nearby ITFS receive sites prior to commencing two-way services to nearby consumer locations, and banned the use of omnidirectional antennas at consumer locations. The inability of consumers to install their own equipment is a limiting factor in deployment of second-generation equipment, independent of the inability to use the spectrum for mobile receivers. Also, “off the shelf” non-professionally installed CPE is vital to bringing costs into competition with DSL and other broadband data offerings.

Overview of the Plan

The purpose of the change in the FCC Rules is to:

• Eliminate the regulatory burdens and costs imposed by site-by-site licensing of MDS and ITFS facilities. The proponents want to go to a system similar to that used in the cellular regulations, in which each licensee has a Geographic Service Area and he may, within certain limits, place his transmitter and receive sites wherever he desires within that GSA.
• Eliminate the need for professional installation of receive sites, and for fixed receive locations.
• Modify the interference protection rules, because they have prevented licensees from providing the desired two-way wireless services throughout their authorized service areas.
• Establish a flexible bandplan that will accommodate and protect both one-way, high-power, high-site operations and advanced two-way cellularized operations.
• Eliminate the interleaved channel plan.
• Remove “regulatory underbrush” to bring the MDS/ITFS rules into conformance with FCC standards for geographically licensed flexible use services.

Proposed “Default” Frequency Allocation Plan

The proponents have designed a plan to accomplish these goals. The band is divided into segments, one of which is designed for high-powered downstream operations from a single tall transmitter location, two of which are designed for two-way cellularized operations, and two of which are used as “guard bands”. The technology to fully utilize these “guard band” areas does not presently exist, but it is anticipated that this spectrum will not lie fallow. Although uses of the “guard band” areas are intended to be secondary (meaning that any use must accept interference from but may not give interference to the operations on either side of the band), spectrum is too valuable to lie fallow. We expect innovative uses for this spectrum to be found soon after deployment of the plan. Most licensees will have a contiguous 1.5 MHz wide slice of guard band spectrum assigned to them.

The parties in a market may modify the “default” frequency allocation plan, if they so agree, but is offered as a solution in case such agreement cannot be reached. It re-allocates the spectrum in such a way that each ITFS licensee continues to receive the same number of MHz, but it is divided up differently. The MMDS licensees actually receive a tiny amount more spectrum than they presently have, since the I channel spectrum is returned to them.

Each ITFS licensee who presently has 4 interleaved ITFS channels, each 6 MHz wide, will end up with three contiguous channels of 5.5 MHz each in the lower or upper band, one channel of 6 MHz in the mid-band for traditional operations, and three contiguous channels of 0.5 MHz in the guard bands. In addition, the 0.125 MHz-wide I channels currently licensed to ITFS stations will be aggregated so that the four may be combined into a single 0.5 MHz-wide channel.

Each MMDS licensee who presently has 4 interleaved MMDS channels of 6 MHz will end up with three contiguous 5.5 MHz wide upper band channels, one channel of 6 MHz in the mid-band, and three channels of 0.5 MHz in the guard bands. In addition, spectrum representing the I channels originally assigned to the E and F when they were ITFS channels (and removed when they became MMDS channels) will be returned. There are four contiguous 0.125-MHz wide I channels assigned to each group of four MMDS channels.

The single-channel H channel licensees will each end up with a single 5.5 MHz wide upper band assignment, one 0.5 MHz wide guard band channel, and one 0.125 MHz wide I channel will be added.

Tables I through III show the actual proposed assignments. Tables IV and V show the assignments under the present United States rules.

Additional information about broadband video and data systems may be found on the LBA web site. Check out http://www.Lbagroup.com for information on this and other topics.

Table I: Default Assignments Of Lower, Mid And Upper Band Segments

Lower band segments can be used for TDD or Upstream FCC. Upper band segments can be used for TDD or Downstream FDD. These channels are each 5.5 MHz wide.

Mid band segments are the traditional high-powered “big stick” downstream channels, and operations of up to +33 dBW are permitted. They are 6 MHz wide channels. The interference rules remain unchanged. With the consent of all licensees, they may be used for upstream operations.

Table II: Default Licensing Of Transition Bands
(J And K Bands)

These channels operate secondary to all other channels. They must operate at low power levels.

Table III: Default Licensing Of I Band

The I channels were assigned to each ITFS channel and to MMDS channels E1, E2, F1 and F2, but the interleaved plan was followed. Under the new plan, channels E3, E4, F3, F4, H1, H2 and H3 gain an I channel and the I channels associated with a single channel group are contiguous.

Table IV: Current Channel Plan

The current interleaved channel plan, designed to meet the technological constraints of 1960’s era equipment.

Table V: Current assignment of I channels

The current assignment of I channels, intended for upstream response from ITFS receive sites.

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