"We are a Baby Qualcomm">
10/29/99 - Cisco cuts fresh path to broadband wireless
Oct. 29, 1999 (Electronic Engineering Times - CMP via COMTEX) -- SAN JOSE, CALIF. - Broadband wireless got a shot in the arm last
week when router king Cisco Systems Inc. brokered a broad coalition of companies behind a coding scheme that has the potential to
lower costs of the technology into the realm of mass-market appeal. Cisco rounded up 10 backers to promote vector orthogonal
frequency-division multiplex-ing (VOFDM). The technology promises to reduce the costs of 30-Mbit/second wireless connections to
less than $50-within striking distance of cable modems and digital subscriber lines.
"Initially, we thought wireless access might serve limited markets, but with the potential to drive costs of the electronics below $50 for
the customer premises, the companies involved in VOFDM could change the equation," said Gregg Lowe, vice president of worldwide
ASICs at Texas Instruments Inc. (Dallas), which will make ASICs and DSPs using VOFDM.
But analysts were cautious about whether VOFDM will be the slam-dunk Cisco and its partners see for wireless services based on
Metropolitan Multipoint Distribution Service networks operating at 2.5 and 5 GHz. "Given the false starts many carriers have had in
introducing MMDS, it"s hard to see the infrastructure taking off, even with the availability of lower-cost electronics based on this new
technology," said Gary Arlen, telecommunications analyst with Wideband Inc. (Bethesda, Md.).
Nevertheless, Cisco has contracted with Broadcom Corp. (Irvine, Calif.) to develop a media-access control (MAC) device for VOFDM.
The BCM2200 could be used in customer-premises modems for broadband wireless Internet access.
Cisco and its system partners also will work with TI on DSP and ASIC solutions, both for customer premises modems and for
headends multiplexing many VOFDM subscriber services. Other partners include Bechtel Telecommunications, EDS, KPMG
Consulting, LCC International, Motorola, Pace Micro Technology, Samsung and Toshiba.
Microwave MMDS services were touted in the early 1990s as a one-way broadcast method, often dubbed "wireless cable." The
scheme, heralded for its non-line-of sight transmission, which simplifies deployment, saw only limited urban success in 2.5- and 5-GHz
frequency bands. Trade groups like the Wireless Cable Association have promoted using MMDS as a two-way packet service for
Internet access, but this has remained a dream.
Steve Smith, director of marketing for broadband wireless at Cisco, and Tim Lindenfelser, Broadcom"s vice president of marketing,
cited the same business events in 1998 as spurring an effort to create a multivendor coalition around VOFDM: the parallel moves by
MCI WorldCom and Sprint to buy up moribund "wireless cable" MMDS operations. Sprint bought American Telecasting Inc., while MCI
WorldCom acquired CAI Wireless Inc. When MCI WorldCom offered to acquire Sprint in early October, the effort to promote VOFDM for
consumer markets moved into high gear.
"Suddenly you had a unified footprint from national carriers, and MMDS looked a lot more viable," Lindenfelser said.
The coalition still is hammering out its standards strategy. Smith said that part of the effort involves putting chip-level interfaces in place
via informal channels, but if a standards effort is deemed important, the coalition likely will turn to the IEEE"s new 802.16 group for
broadband wireless (see Jan. 25, page 1). The group may also work with the European Telecommunications Standards Institute"s
Broadband Radio Networks committee, but the coalition views the MMDS-oriented Wireless Communications Association as primarily
a Washington lobbying body.
Cisco"s strategy in DSL and cable modems is to be involved in headend and central office equipment such as routers and DSL access
multiplexers, but to take the plunge into customer premises modems for broadband services only where absolutely necessary. This is
why Cisco turned to Broadcom for a standard modem, implementing MAC and physical-layer parts of VOFDM in a single chip. Cisco
has urged Broadcom to sell the BCM2200 into merchant markets.
Broadcom"s Lindenfelser said the new chip, which will integrate dual OFDM receivers, can use significant portions of the company"s
quadrature amplitude modulation (QAM) cable modem chip set. It will include many features from the new Docsis 1.1 cable modem
spec, he said, including packet prioritization to support low-latency voice, in-line encryption and decryption using the Data Encryption
Standard, and support for symmetric services.
The VOFDM codes, which Cisco acquired from Clarity Wireless Inc., are similar in some senses to the QAM cod-ing used in cable
modems. Wireless modems must enforce tight power control to combat rain and foliage fade, using special system-ID circuitry in the
transceiver. Although implementation is slightly more complex, Broadcom should be able to drive the modem chips to near price parity
with cable modem MACs, Lindenfelser said.
Broadcom will limit its participation to baseband and physical-layer transceiver functions, and will not move into RF/IF blocks. Although
VOFDM can be used in many frequency bands, Lindenfelser predicted that near-term systems will be dominated by 2.5-GHz
implementations, with 5-GHz systems coming later.
The involvement at TI stemmed from Clarity"s use of TMS320C6x family members in banks of DSPs in the initial VOFDM headends.
Lowe said that TI will continue to supply standalone DSPs to all the players in VOFDM headend equipment. But the real excitement for
the company, he said, will be in developing a low-cost customer premises solution combining DSP cores, TI"s ASIC backplane and
MAC technology gained through the acquisition of Libit Signal Processing Inc. (Tel Aviv), the specialist in cable modem MACs. The fact
that Libit"s intellectual property can be used in cable, DSL and wireless markets, Lowe said, indicates the degree of design reuse that
can be accomplished in different broadband segments.
While VOFDM makes the most sense in frequency bands between 2 and 15 GHz, Cisco executives said the new initiative does not
mean the company is cooling its joint investment with Motorola Inc. in Local Multipoint Distribution Service networks, originally
developed by TI and Bosch. The 28-GHz LMDS is a millimeter-wave cousin to MMDS.
Cisco"s Smith said that LMDS networks may prove more appropriate for some metropolitan business services. But using VOFDM in
simpler MMDS networks could entail a larger potential market for the lower-frequency services, he said.
OFDM is a modulation scheme that allows a frequency band to carry multiple channels, usually with some overlap in channel
assignment to improve capacity. Interest in variants of OFDM coding have pulled in large crowds at IEEE conferences in the last six
months.
Coherent OFDM has been used in European digital video broadcast applications, coded OFDM is being studied for MMDS and LMDS
applications, and in late June Wi-LAN Inc. (Calgary, Alberta) launched a program for using its wideband OFDM in wireless local loops
(see June 27, page 1).
Cisco"s Smith said that a key advantage of vector OFDM is its support of directional sectorizing and antenna spatial diversity, leading
to much lower costs in antenna infrastructure deployment. The vector coding makes it easier to synchronize on OFDM bursts.
Synchronization can be important in always-on consumer broadband systems, where end users may be away from a PC terminal for
hours on end, and then come back expecting instant access at full multimegabit rates.
In an LMDS system, this can prove difficult, Smith said, while in a VOFDM MMDS system, synchronization should be almost
instantaneous.
"This also provides a solution for those areas of dense foliage, which have always been problematic in traditional LMDS, because you
can deploy low-cost repeaters in a VOFDM system," Smith said. To date, the coalition has not approached repeater manufacturers,
though Smith said that could be the next step for expanding the base of VOFDM support.
Patent debate
One potential hurdle is patent overlap between the Cisco/Clarity VOFDM work and Wi-LAN"s W-OFDM. Wi-LAN has been pursuing its
patent rights fairly aggressively. Two weeks ago, the Canadian company notified the International Telecommunication Union that all
current third-generation (3G) cellular proposals for using wideband CDMA will likely infringe on Wi-LAN patents. Wi-LAN proposed
licensing one of its patents for all 3G implementers.
"We are a baby Qualcomm, with all that implies about seeking fair use, " said Hatim Zaghloul, chairman of Wi-LAN. He was referring to
CDMA powerhouse Qualcomm Inc. (San Diego), which does a brisk business in licensing.
Zaghloul termed the Cisco announcement vindication for OFDM coding and good news for all in broadband wireless. On a first-pass
analysis of the VOFDM work, Zaghloul said he believed any OFDM method using multichannel modulation methods similar to ADSL
would overlap with Wi-LAN patents. It is also possible that the VOFDM work may be similar to the Blast technology Lucent
Technologies Inc. introduced last year, he added. Many of the VOFDM partners already have approached Wi-LAN to talk about OFDM
coding issues, Zaghloul said.
But Smith of Cisco expressed little concern over patent interference with Wi-LAN. Clarity had 30 patents awarded and more than 1,000
claims, Smith said, whereas in his view Wi-LAN has only one patent that appears to be relevant to VOFDM.
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By: Loring Wirbel
Copyright 1999 CMP Media Inc.
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