This article from X-Change Magazine talks about how CLECs are now looking at wireless.
===
Finding an "In"
Broadband Fixed Wireless Gives CLECs New Entry Strategy
By Charles A. Riggle
Frustrated with the prospect of working through local incumbent carriers
to reach customers, some competitive local exchange carriers (CLECs)
have turned to broadband wireless access (BWA) technology.
According to Ovum Ltd., London, broadband wireless will serve nearly
40 million subscribers by 2005. Meanwhile, Pioneer Consulting,
Cambridge, Mass., predicts that local multipoint distribution system
(LMDS) operators alone will earn more than $6.5 billion by 2007.
Last March the Federal Communications
Commission (FCC) auctioned 864 licenses in
the 28 gigahertz (GHz) and 31GHz bands,
giving more than 100 organizations access to
either the 1150 megahertz (MHz) A-band or
the 150MHz B-band, and in some cases both.
While some of these licenses were won by
organizations comprised primarily of venture
capitalists or entrepreneurs, others were
captured by telecommunications entities with
existing experience in wireless access and/or
Internet service provider (ISP) and CLEC businesses. And, in addition to
LMDS, some carriers are building systems using other millimeter wave
frequencies from 24GHz to 38GHz.
Also last year, the FCC issued its Report and Order providing for
flexible, two-way use of the microwave multipoint distribution system
(MMDS) spectrum at 2.5GHz. This ruling opens up microwave spectrum
that once was used primarily for distribution of multichannel digital and
analog video to be utilized for delivering high-speed data and voice, or
any other two-way broadband service demanded by business and
residential end users. Several existing U.S. MMDS operators already are
taking advantage of this new regulatory action.
Internationally, opportunities for fixed broadband wireless access appear
even greater than those in the United States due to the lack of existing
wireline infrastructure in many countries and the rapid growth in demand
worldwide for high-speed access. Even prior to the recent events in the
United States, local multipoint communications systems (LMCS), the
Canadian equivalent to LMDS, was auctioned and now has been
deployed in several initial markets to deliver broadband services to
businesses. Industry Canada, the Canadian counterpart to the FCC,
plans spectrum auctions this year covering the 24GHz and 38GHz
spectrums. At least 20 countries, including Argentina, New Zealand and
Venezuela among others, either are allocating or considering the
allocation of LMDS, two-way MMDS and other spectrum for
high-speed services by BWA platforms.
While on the surface these spectrum allocations may seem to be in direct
competition with one another, in reality microwave (MMDS) and
millimeter wave (LMDS/LMCS/24GHz/38GHz) BWA systems provide
their respective license-holders with unique opportunities to address the
growing demand for high-speed data and voice access. Each type of
spectrum allocation is well-suited to serve a specific market segment.
LMDS
Graph: Local Multipoint Distribution System
The U.S. LMDS A-band is comprised of 1150MHz, one large segment
from 27.5GHz to 28.35GHz, and two smaller segments from 29.1GHz to
29.25GHz and 31.075GHz to 31.225GHz. This spectrum can be used in
virtually any configuration, the exception being the 29GHz segment, which
must be used only for downstream configurations to mitigate possible
interference with certain satellite receive stations. The B-band is smaller
but is still substantial, with a total of 150MHz available. This is allocated
as two segments of 75MHz each, from 31.0GHz to 31.075GHz and
31.225GHz to 31.3GHz.
The fact that LMDS is in a millimeter wave spectrum--like LMCS,
24GHz and 38GHz--means that it has certain propagation properties that
make it suitable for applications that do not require transmission over long
distances and that are line of sight (LOS). One property that is especially
critical is signal attenuation during intense rainstorms. To achieve typical
telecommunications requirements of 99.99 percent availability or better,
LMDS cells shouldn't have a radius of more than one to two miles. This,
combined with its copious amounts of available bandwidth, make LMDS
an ideal delivery platform for sites in dense areas that require very large
amounts of bandwidth. Urban metropolises with many closely spaced
buildings, each housing many individual businesses, epitomize this
scenario.
Today, wireless CLECs can use point-to-point millimeter wave radios to
deliver this very high bandwidth using individual radios at each hub
site--one for each transmission link. Carriers such as Advanced Radio
Telecom Corp. (ART), Bellevue, Wash.; Teleport Communications
Group Inc., New York; and WinStar Communications Inc., New York,
each with experience at 38GHz, have used this BWA architecture
successfully for several years. Recently, however, many of these wireless
carriers have conducted limited trial deployments of first-generation
point-to-multipoint LMDS equipment. This new architecture reduces the
number of individual hub radios and provides for more efficient use of the
available wireless spectrum.
Point-to-multipoint systems operate on a time division multiple access
(TDMA) basis, meaning they share any unused bandwidth in the
upstream on a statistical basis to provide bandwidth-on-demand to
individual end users. As such systems evolve and become more widely
deployed, these carriers no longer will have to provide bursty-type data
access over a dedicated and constant bandwidth pipe.
For this urban target market, LMDS CLECs will tend to deploy many
small cells as an extension to their fiber rings. This will enable them to
deliver bandwidth faster and more cheaply than by burying more fiber,
crossing more rights-of-way and installing more synchronous optical
network (SONET) multiplexers to provide the needed access drops into
office buildings.
Depending on customer needs, both point-to-point and
point-to-multipoint architectures will be used for high-speed access in the
same markets. Point-to-point will provide the customers who exhibit the
largest bandwidth needs with dedicated service, while smaller businesses
and those with primarily bursty traffic (such as Internet access) likely will
use point-to-multipoint. Newly established LMDS carriers without
existing fiber backbones either will lease fiber capacity from an
established competitive access provider or construct wireless
point-to-point backbone links between their point-to-multipoint hubs
using wireless spectrum. As capacity on their network grows, these
carriers will need to expand by building out their own fiber rings or
merging with the local fiber backbone providers.
MMDS
Graph: Microwave Multipoint Distribution System (MMDS)
MMDS, in the 2.5GHz band, includes several 6MHz channels initially
allocated for multichannel video broadcast transmission. This service is
made up of a two-channel band called multipoint distribution system
(MDS), ranging from 2150MHz to 2162MHz and a larger spectrum
band of 29 channels from 2500MHz to 2686MHz. The MMDS band
also is broken down by ownership into commercial operators that own
spectrum in channel groups E, F, H and MDS 1&2, as well as the
Instructional Television Fixed Service (ITFS) licensees that typically own
one or more of the A, B, C, D and G groups. These ITFS operators
primarily are educational and religious broadcasters with FCC-imposed
requirements on the number of hours that they provide programming.
In most MMDS systems, the MMDS licensees have lease agreements
with the individual ITFS owners defining such relationships as excess
channel bandwidth usage, times of use, etc. These relationships allow
commercial operators to provide an increased number of channels of
service while providing the ITFS operator with the benefits of expanded
viewership, technical support and other mutually conducive advantages.
Unlike LMDS and other millimeter wave systems, MMDS is not
hampered by rain and has good LOS propagation properties, so MMDS
typically can achieve an acceptable availability performance of 99.99
percent at distances greater than 10 miles in radius. However, the
MMDS band does not provide as much available bandwidth to deliver
services as LMDS does. Consequently, MMDS is well-suited for
delivering services--such as high-speed Internet access--in suburban and
other less-dense markets including small businesses, small office/home
office (SOHO) and technically affluent family residential end users. It
should be noted however, that organizations attempting to use
off-the-shelf cable modem products for wireless applications likely will
run into performance problems due to forward error correction (FEC)
and equalization, as well as media access control (MAC) software that
must consider modem control features that reflect the differences between
the transmission channel of coax and that of a wireless air path.
For the less-dense markets and suburban markets where cable data
modem services are slow to be deployed, MMDS provides
license-holders with a high-speed platform that can be installed and
maintained quickly and economically. However, MMDS requires LOS,
so it may be difficult to reach some areas obstructed by buildings or other
objects.
Similar to its distant cousin LMDS, the technology currently used for
two-way MMDS is time division multiplexing (TDM)/TDMA, providing
bandwidth on demand for loss-of-signal customers requiring access to
bursty data. Like LMDS, two-way MMDS also is being successfully
deployed with first-generation hardware through initial market trials, albeit
in large multisectored, single-hub configurations. These installations are
providing operators such as Wireless One Inc., Jackson, Miss.; People's
Choice Television Corp., Shelton, Conn.; and WavePath, Mountain
View, Calif., with a valuable head start at the transition from being a
multichannel video provider to also providing services as an ISP or
CLEC.
Future Trends
Both LMDS and MMDS have significant opportunities in the future as
BWA becomes more widely deployed around the world. These
platforms stand apart from more traditional data- and voice-delivery
methods due to their flexibility, the power of their network management
systems and the speed with which they can be deployed and redeployed.
Graph: Broadband Wireless Propagation Systems
Second-generation BWA systems for LMDS and MMDS will take on
features typically seen in wireline telecommunications equipment. These
physical-layer features primarily focus on product reliability and link
availability and include such attributes as multiple modems per chassis,
N:1 redundancy in the access modems, 1:1 redundancy on power
supplies and hot-swappability of all modules in the chassis. On many
occasions, those redundancy features were deemed unnecessary in the
dedicated point-to-point links deployed until now. By providing multiple
transmission channels per chassis with integrated redundancy, BWA
platforms can supply large amounts of instantaneous bandwidth reliably to
demanding business and residential end users in direct competition with
traditional wireline methods.
BWA platforms will provide a variety of network and end-user service
interfaces to let carriers serve a variety of customer needs and to interface
with popular network protocols. One feature of great significance for
competitive carriers is quality of service (QoS). All BWA systems,
whether based on a proprietary air interface or rooted in a standard such
as asynchronous transfer mode (ATM) or Internet protocol (IP), will
need to provide several levels of QoS to allow guaranteed bandwidth
access and service level agreements (SLAs) by competitive wireless
carriers. Sophisticated end users must be able to see that they are in fact
receiving the constant and variable data rates for which they contracted.
Meanwhile, network management in point-to-multipoint BWA platforms
will go well beyond switching to a hot standby as in older point-to-point
systems. The network management systems that administer customer
provisioning, manage bandwidth, track system performance and issue
network alarms--not to mention customer billing records--will be the
heart of future BWA platforms. And, to gain long-term acceptance and
critical mass, BWA platforms will have to be simple and easy to install.
Finally, BWA platforms will support a variety of traffic types, including IP
data and voice, frame relay and ATM, and will be carried over the
wireless air path from numerous simultaneous customers. These packets
then will be muxed onto backbone networks.
It's clear that industry momentum has shifted from switched voice and
data access to a future incorporating more flexible packet and cell-based
systems. Broadband wireless access is uniquely poised to make a major
impact on that inevitable change.
Charles A. Riggle is senior product manager for ADC
Telecommunications Inc.'s Broadband Wireless Access Division,
McMurray, Penn. He can be reached via e-mail at
chuck_riggle@adc.com.
Copyright © 1999 by Virgo Publishing, Inc.
Please read our legal page before using this site.
To make changes, use the Back button on your browser, or press "Edit"
Words that might be incorrectly spelled are highlighted in red.
Your message has not been posted yet.
You will still have 15 minutes to edit your message after you press "Publish"
|
