TECHNOLOGY· APPLICATIONS · PRODUCTS · SOLUTIONS
`A PENTON PUBLICATION $10.00
`DECEMBER 1, 1997
`•• I I
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`(cid:127)
`
`MCNS/DOCSIS MAC Clears Path For Cable-Modem Invasion p. 69
`Annual IEDM Conference Examines Leading-Edge Device Developments p. 39
`At IEDM: Memory, Logic Power Devices, EDA, Sensors, And Displays p. 40
`Line-Driver Design For Broadband Communications Applications p. 81
`Parasitic Extraction Tools Aid DSM IC Designs p. 97
`Harness The Power Of The ACPI/Smart Battery Standard p. 113
`Pick The Perfect Chassis To Ensure System Longevity p. 127
`
`LG Ex. 1007
`LG Electronics Inc. v. ParkerVision, Inc.
`IPR2022-00246
`Page 00001
`
`

`

`If yo(!.'re charged with designing low-power applicat;ic)ls,
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`A 48MIPS/50MHz RISC core design with I/0 intelligence
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`and interrupt performance built in. Plus, its development
`
`tool chains are fully complete and validated to interoperate,
`
`greatly reducing design time. In other words, it's ready to fly!
`
`To find out how Motorola can help you save the day,
`
`direct your mouse to www.motorola.com/mcore
`
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`~ l!lll MOTOROIA, INt All RIGHTS REsal\'ED. MOTDRDIAAND @ ARE REGISTERED TRAOEMA!l!S
`AND THE M•CDRE NAME AND LOGO ARE TRADEMARKS OF MOTOROIA, INt MIGKTY MOUSE, TM & ~ 1997 VIACOM INrL INC.
`
`IPR2022-00246 Page 00002
`
`

`

`ELECTRONIC DESIGN
`
`TECHNOLOGY• APPLICATIONS• PRODUCTS• SOLUTIONS
`December 1, 1997 Volume 45, Number 27
`
`EDITORIAL OVERVIEW
`
`DEPARTMENTS
`
`Upcoming Meetings •. . 12,
`.. .... .. 16, 18, 54
`
`Editorial .... .. .. .... 22
`• Tiny Engines Fuel A
`Revolution
`
`Technology Briefing ••• • 24
`• Consumer Electronics'
`Potential
`
`Technology
`Newsletter ••... . 27, 30
`
`Technology
`Breakthrough . ••..•• • 33
`• 35-GHz 0.5-W GaAs
`pH EMT points the way
`toward low-cost volume
`production of MOCVD
`MMICs
`• 0.1-mm electrostatic
`microrelays switch at up
`to100GHz
`• Development of blue
`phosphor spawns full(cid:173)
`color EL displays
`
`Info Page ••..••.•.• • 10
`(how to find us)
`
`Index of Advertisers •• 184
`
`Reader
`Service Card ••.. 184A-D
`
`(cid:127) MCNS/DOCSIS MAC Clears Path For Cable-Modem Invasion 69
`(cid:127) Annual IEDM Conference Examines leading-Edge Device Developments 39
`(cid:127) At IEDM: Memory, logic Power Devices, EDA, Sensors, And Displays 40
`(cid:127) Line-Driver Design For Broadband Communications Applications 81
`(cid:127) Parasitic Extraction Tools Aid DSM IC Designs 97
`(cid:127) Harness The Power Of The ACPI/Smart-Battery Standard 113
`(cid:127) Pick The Perfect Chassis To Ensure System longevity 127
`
`TECH INSIGHTS
`39 Annual IEDM Conference Examines Leading-Edge
`Device Developments
`• Hear about the latest in memory and logic
`!Cs, compound semiconductor devices,
`simulation tools, and sensors and displays.
`
`40 Memory And Logic Structures Are Getting Faster
`And Denser
`• Desi.gners detail advanced process techniques
`and finer-dimension design rules at IEDM to
`build next-generation memories and logic.
`
`48 Rivalries Between Silicon And Exotic Semiconductors
`Abound At IEDM
`• SiGe and vanilla silicon move into RF and
`optical applications as compound semi(cid:173)
`conductors stake out their niches.
`
`TECH INSIGHTS
`50 IEDM Focuses On Advanced Device Models
`• Models offer new hope in tackling deep(cid:173)
`submicron issues dealing with process
`accuracy and interconnect.
`
`60 Sensors And Displays Highlighted At IEDM
`• Advanced device structures and new
`technologies are <Ypening the door for emerging
`display and sensor-based applications.
`COMMUNICATIONS TECHNOLOGY
`69 MCNS/ DOCSIS MAC Paves The Way For A
`Cable-Modem Invasion ·
`•
`• The first standards-compliant chip
`means affordable, interoperable,
`cable modems, with speed a ncl
`security features.
`
`1
`1 "
`
`•
`
`~LECTRONIC DESIGN (ISSN 0013-4872) is published twice monthly except for 3
`issues in May_, 3 issues in August, 3 issues in October and 3 issues in November by
`Pentan Publishing Inc., 1100 Superior Ave., Cleveland, OH 44114-2543. Paid rates
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`
`CoP.yright 1997 by Penton Publishini, Inc. All rights reserved. The contents of this
`publication may not be reproduced ,n whole or in part without the consent of the
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`
`IPR2022-00246 Page 00003
`
`

`

`(cid:127) Highlights and insights from the frontline of the communications revolution
`MCNS /DOCSIS MAC Clears A Path For
`The Cable-Modem l1nvasion
`
`The First Standards-Compliant Chip Means Affordable, Interoperable,
`Cable Modems, With Speed And Security Features.
`Lee Goldberg
`
`Wit h the introduction of
`
`the BCM3220 multime(cid:173)
`dia cable networking
`systems/Data-Over-Cable-Ser(cid:173)
`vice Interface Specification
`(MCNS/DOCSIS) compliant
`media-access controller (MAC)
`chip, the cable data revolution
`has begun in earnest. By rolling
`out the first integrated imple(cid:173)
`mentation of the cable industry's
`recently developed DOCSIS,
`Broadcom Corporation has
`paved the way for the rapid de(cid:173)
`velopment of inexpensive con(cid:173)
`sumer-oriented cable data appli(cid:173)
`ances. This move could provide a
`critical jump-start for the
`emerging cable data industry. If "1lM, .BIi.•: '.~.-
`1:11._
`II
`the next year goes according to
`II ~
`• _ &
`plan, we may see a device that
`delivers multimegabit down- •--(cid:173)
`stream Internet access being
`sold at K-Marts and electronic discount
`stores at prices comparable to today's
`56-kbit POTS modems.
`
`The Broadband Wars
`The development of DOCSIS and
`the introduction of the BCM3220 mark
`the first hopeful chapter in the trou(cid:173)
`bled history of cable media's efforts to
`maintain its dominant role in captur(cid:173)
`ing the hearts, minds, and eyes of the
`American consumer. In the early
`nineties, the cable television industry
`faced a double threat: While saturated
`subscriber markets yielded flattening
`revenues, satellite television, sophisti(cid:173)
`cated computer games, and Internet
`
`the IEEE's 802.14 cable data
`standards committee, a group
`of large cable interests formed
`the MCNS group. Comprised
`of heavyweights like Comcast
`and Time-Warner, MCNS
`teamed with the cable indus(cid:173)
`try's research consortium, Ca(cid:173)
`ble Labs, Louisville,
`Colo., to produce
`their own open standard for
`1, moving data between cable
`network headends and sub(cid:173)
`scriber's homes.
`
`Enter DOCSIS
`The first fruit of this alliance is
`the DOCSIS specification, de- !
`veloped by a group of manufac(cid:173)
`turers, under the direction of
`MCNS and Cable Labs. Partic(cid:173)
`ipants in the initial develop-
`ment ofDOCSIS included Gen(cid:173)
`eral Instruments, LAN City (now a
`surfing began to erode cable's near-
`part of Bay Networks), and Broadcom.
`lock on passive leisure activities.
`After several ill-fated adventures This spec outlines the physical layer in(cid:173)
`with video-on-demand, interactive
`terfaces, MAC and transport prot o(cid:173)
`shopping, and other attempts to die-
`cols, security provisions, and other
`tate consumer taste, cable marketeers
`specifications necessary for designing
`stumbled over the obvious hot applica- , interoperable cable data components.
`tion, broadband Internet access. Once : Subsequent fine-tuning was per(cid:173)
`early trials demonstrated the eco- ' formed in an open forum hosted by Ca(cid:173)
`nomic potential, it became clear that ble Labs and attended by most major
`the only way to achieve a critical mass players in the cable industry. The re(cid:173)
`ofusers was to develop a transmission
`sult is a standard that meets the needs
`standard that would enable the pro-
`of current users and anticipates the de(cid:173)
`duction of mass-produced, inexpen- mands of future applications.
`sive, interoperable cable modems and
`DOCSIS is designed to employ one
`, or more unused video channels within
`set-top boxes (Fig. 1).
`Frustrated by the slow progress of : the 54-to-860-MHz cable broadcast
`
`-
`
`-
`
`IPR2022-00246 Page 00004
`
`

`

`w,•ar/Jl'/IWU!!JU'lit:w•tsilfl'H'A'IW ::, 1ANUAKu::» - nA::,1::u '-ADL1::-muu1::m mA (.; J
`
`processing
`
`s
`
`C
`
`Memp,racasor
`MAC
`MAC
`header
`.. message
`processing
`processor
`(with CRC)
`
`....
`
`allocatlOII
`map,-or
`I Map parser
`
`!
`CPU interface
`4
`t
`Management
`llpstrllftl
`I
`infomation
`Dual-porf l ~
`block (MIB)
`cont:onerl
`Key
`
`Down•
`
`C,
`
`a,
`~
`
`i!'"
`
`e
`c.:, -
`DMA
`~
`~ , 16
`..,
`::E
`;' Data
`E'E
`-i!
`a:
`~ ~ -c: . .
`"'
`i
`,20
`-;; :,~
`-
`..,c::,
`C
`11 ti
`e
`3:c
`CIE :rr :i
`~
`C, " '
`~
`-
`Control
`I
`,16
`~1--i- - ---t1-+-+i1 ,1:-Da-=:-ta•
`7 ,__ _ _ _ +;,2=0 ..
`'Address
`CPU bus
`
`-
`Dllldlmll
`Downstm
`- ~ header -=
`-
`I"' ~ DIA ....
`stream - 'E
`m P~ MAC
`I PHY I i
`t;;':-::8 ~,-+Ll i_nte_rf_ac_.e r
`-
`...
`
`Clock
`,Data
`
`BCMJll&
`or
`BCM3118 Control
`-
`
`.........
`
`Timing
`recovery
`circuit (TRC)
`To
`L . _ _
`tuner and
`Serial
`EEPROM
`programming
`-.--.,__-t-~
`SPI
`interface
`bus
`(SPI)
`
`Reference
`clock
`
`spectrum to transmit IP-based
`data across hybrid fiber coax-
`ial networks . Complex
`phase/amplitude modulation
`enables each 6-MHz down-
`stream channel to bring data
`into subscribers' homes at up
`to 38 Mbits/s. Depending on
`the bit rate selected by the op(cid:173)
`erator, the shared downstream
`channel uses either 64- or 256-
`point quadrature-amplit ude
`modulation (QAM). While little
`is known about what actual
`bandwidth requirements will
`be, initial results from field tri(cid:173)
`als suggests that a single chan(cid:173)
`nel will provide groups of 200
`to 1000 subscribers with Inter(cid:173)
`net access that is substantially
`faster than today's best POTS(cid:173)
`based services.
`For communication from the
`home to headend, DOCSIS
`uses the 5-to-40-Hz sub-split
`band as a return path. Using
`QPSK today, or 16-QAM in sub(cid:173)
`sequent versions, the upstream
`channel has a theoretical maxi(cid:173)
`mum throughput of 10 Mbits/s
`(see "Broadband To The Home: Chal(cid:173)
`lenges On the Last Mile," Electronic
`Design, Oct. 2, 1995,pp 67-83) ..
`Since DOCSIS also is intended to
`support IP-based video, pr ovisions
`have been made to support several
`levels of quality of service (QoS). This
`
`1
`DES
`Clock
`_[
`t
`~ BCM3037 ~S~er~ial-d-ata-r-....,___,_ __ - ,_ encrypt
`Upstream C8llbul
`Control
`L
`
`CRC
`
`2. The BCM3220 MAC chip incorporates all control, stream-processing, and security functions required for a
`MCNS/DOCSIS-compliant cable modem. A memory-based DMA interface assures efficient data transfers to
`and from the host controller. Both baseline and high-security modes also are supported.
`
`Coax
`connector
`
`Diplex
`filter
`
`54-860 MHz
`
`Low-pass
`filler
`
`Low-pass
`filter
`
`feature allows it to accommodate both : businesses which need them.
`t r adit ional connectionless Internet :
`traffic, as well as latency-sensitive : MPEG Everywhere
`One interesting aspect of DOCSIS
`multimedia streams. Selectable QoS
`is that it uses MPE G II transp ort
`also will let cable companies offer
`tiered services with various guaran(cid:173)
`streams to move IP data. While not es(cid:173)
`teed bit rates and levels of latency to
`sential for t oday's applicat ions, the
`standard's developers were looking
`toward the future. Today, MPEG en(cid:173)
`capsulation provides DOCSIS with a
`reliable, well-defined method of set(cid:173)
`ting up multiple channels within a sin(cid:173)
`gle data str eam. In the near future,
`MPEG encapsulation will allow a sin(cid:173)
`gle cable modem to support multiple
`sessions and multiple users, as well as
`delay-sensitive multimedia streams
`for voice or video over IP.
`Using MPEG II transport streams
`also will allow DOCSIS to interoperate
`with the Open Cable standard for digi(cid:173)
`tal cable television that is currently un(cid:173)
`der development. Open Cable also em(cid:173)
`ploys MPEG II transport streams for
`all of its media flows. This feature
`should greatly simplify traffic switch(cid:173)
`ing and processing within tomorrow's
`cable networks
`Although it has some similarities to
`the carrier-sense multiple-access/colli(cid:173)
`sion-detect (CSMA/CD) protocol em-
`
`BCM3037
`upstream
`QPSK/16-QAM
`modulator
`
`Clock
`
`Data
`
`BCM3220
`MAC
`
`Microconlroller
`with Ethernet MAC
`
`Clock
`
`Data
`
`, BCM3116
`: OAM receiver
`' with FEC
`
`10Base·T
`transceiver
`
`RJ45
`connector
`
`I. A DOCSIS-compliant cable modem receives its data over unused 6-MHz video channels within
`the normal cable spectrum. Upstream traffic is carried back to the system headend in the 5-to·
`45-MHz sub-split band. To ensure that the modem will operate properly and not interfere with
`other units, bath the downstream receiver and upstream modulator/ transmitter operate under
`the control of the BCM3220, or other DOCSIS-compatible MAC.
`
`IPR2022-00246 Page 00005
`
`

`

`-,,,M@mtdo-u,11nmM1•x• STANDARDS - BASED CABLE - MODEM Mill
`
`1byte
`
`1 byte
`
`1byte
`
`Request
`(upstream only)
`
`2 bytes
`
`SID
`
`Other EH elements
`
`FC
`(1 byte)
`
`MAC_PARM
`(1 byte)
`
`LEN
`(2 bytes)
`
`Extended header
`(4 to 255 bytes)
`
`HCS
`(2 bytes)
`
`Packet PDU
`(18 to 1518 bytes)
`
`FC type
`= 00
`
`FC PARM
`
`EHDR_ON
`=1
`
`DA
`(6 bytes)
`
`SA
`(6 bytes)
`
`Type/Len
`(2 bytes)
`
`User data
`(0 to 1500
`bytes)
`
`CRC
`(4 bytes)
`
`DOCSIS Security: Baseline Privacy
`S ecurity for the DOCSIS
`
`Type
`
`BP EH
`element
`(4 to 5 bytes)
`
`cable modem system is
`divided between an
`elaborate Full-Security
`Specification with remov(cid:173)
`able, renewable security
`modules, and a low-cost, sim(cid:173)
`pler scheme called Baseline
`Privacy (BPI). BPI is based
`on full-bodied concepts, be(cid:173)
`ginning with the 56-bit Digi(cid:173)
`tal Encryption Standard
`(DES) Cipher Block Chain(cid:173)
`ing algorithm, yet unbur(cid:173)
`dened by some of the more
`costly and complex security
`features of its heavy twin.
`All DOCSIS cable modems
`are required to support BPI,
`ensuring that basic data pri-
`vacy is maintained in the shared cable environment.
`: traffic originating from or destined to a particular modem to
`Privacy is more than sufficient for Internet access appli- : identify a 'Iraffic Encrypt ion Key (TEK) to use. Each TEK
`cations because it makes a number of assumptions on the ap- : is a pair of even and odd 56-bit keys. Each key also has a cor(cid:173)
`plication it serves, namely that Internet access is two way, : responding 56-bit initialization vector.
`and therefore not susceptible to passive theft of service; that :
`All DOCSIS frames have header fields that are never
`it's not particularly valuable to anyone, but the user; that re- : encrypted and include an optional field called an Extended
`ally important transactions over the Internet (like banking) : Header. Mainly for protocol expansion, this variable area in
`will be secured with end to end application layer security; : the DOCSIS header is used to contain the Baseline Privacy
`I
`and that by changing keys often, individual keys are not : Extended Header (see the figure). The SID is contained in
`worth the trouble of stealing. It also is much easier to detect : the BPI Extended Header for each frame to identify which
`clones and unauthorized users of cable modems because the : TEK to use.
`service is two-way. The modem system is unlike broadcast
`Each DOCSIS frame that will be encrypted must contain
`pay-per-view video that can be hacked in private--done
`a Privacy Extended Header. The header contaips a type
`modems must not only listen, but speak to be useful.
`and version field as well as the SID identifying a particular
`DES is a cryptographic algorithm that takes binary
`encrypted data flow. The SID field also contai1;1s an en(cid:173)
`coded data and applies a known algorithm using a ran-
`able/disable bit that controls encryption for that particular
`frame and a toggle bit. The toggle bit is used to signify the
`domly generated 56-bit key to produce unintelligible or en-
`current epoch; that is whether the even or odd key is in use
`crypted bits. The algorithm can be known by many but the
`for this frame. This toggle bit allows the protocol to set up a
`data will be unintelligible unless the key is shared by both
`parties. This mutually shared secret allows encrypted traf-
`new TEK in the even key slot while actively using the odd
`fie to remain private to those who have the keys. A 56-bit key. When the first frame to use the new key is received, the
`toggle bit indicates that the epoch has changed and that the
`key has 70 quadrillion possible values, and the only guaran-
`teed way of discovering a truly random key is to try all of other key is now in use. The toggle bit also is the least-sig(cid:173)
`them. Changing keys often reduces the likelihood of sue-
`nificant bit of the 4-bit sequence field that is used to track
`cess even further. The challenge in this type of cryptogra-
`the history ofup to 16 keys by the key exchange protocol.
`phy is how to exchange the secret keys easily, yet securely.
`Baseline Privacy encrypts data in both up and down-
`Cipher Block Chaining is a form of DES that increases
`stream directions of the cable plant using the extended
`the strength of the encryption by using an initialization vec-
`headers to indicate what to do. DOCSIS MAC messages al(cid:173)
`tor sent down with the key to preset its encryption hard-
`low a simple key exchange protocol to operate between the
`ware state. For each eight-byte block encrypted, instead of , headend (or cable modem termination system) and the ca(cid:173)
`resetting or reinitializing, the circuit retains the result from : ble modems. Keys are updated frequently and the registra(cid:173)
`the previous block's encryption. This chaining of results : tion databases are watched vigilantly for clones. This pro(cid:173)
`from one block to the start of the next makes the cryptogra- : vides subscribers with a low-cost but vey effective ''lite"
`phy stronger since a hacker would need to reconstruct the : security solution for ensuring data privacy.
`: Contrilruted by Thmnas J. Qui,gley, director of the Resi-
`entire sequence to break the code instead of just one block.
`Baseline Privacy uses a Service ID (SID) associated with : deni:ial Broadband Business Unit at Broadcom Corp.
`
`IPR2022-00246 Page 00006
`
`

`

`E•U1ti11\1Uitd•M!Eiil(cid:141) :m•H•XDM srANDARDS - BASED CABLE - MODEM MAcJ
`
`ployed by most other 802-flavored me(cid:173)
`dia, DOCSIS employs a time-slotted
`noncontention access scheme for most
`ofits communication. In order to main(cid:173)
`tain order on a busy cable, the MAC
`chip in each subscriber's modem must
`keep track of network timing, as well
`as its place in the overall communica(cid:173)
`tions flow. In contrast to Ethernet's
`CSMA/CD protocol, this more orderly
`access scheme allows cable operators
`to fill their pipelines at up to 75% of
`their theoretical capacity. This factor
`is critical when subscribers are shar- '
`ing bandwidth with 200+ neighbors.
`To satisfy even the terminally para(cid:173)
`noid, two layers of security are pro(cid:173)
`vided within DOCSIS, plus the poten(cid:173)
`tial for a completely shielded
`"tunneling" protocol for sensitive data
`transfers such as personal records or
`credit card numbers.
`If DOCS IS seems a bit complicated,
`it's because it really is. The standard's
`rich feature set and traffic control
`scheme require approximately
`100,000 gates (plus RAM) to imple(cid:173)
`ment, yielding an effective processing
`power of 30 to 40 MIPS. In practice,
`you'd probably need a much faster
`CPU to make sure it was available for :
`all the demanding real-time opera- :
`tions. Despite the complexity, Broad- :
`com was able to follow the evolution of :
`the standard and deliver a product :
`within nine months of its finalization, :
`thanks to its close participation in the
`development committee.
`Another factor that gave Broadcom
`an inside edge on delivering the MAC
`chip is its proprietary silicon compiler
`technology. Their specially developed
`software can translate algorithms di(cid:173)
`rectly to gate layouts optimized for
`minimal cross-talk, propagation delay,
`and other critical parameters. While it
`is primarily used to implement blind(cid:173)
`ingly fast digital filtering and correlat- :
`ing algorithms in CMOS logic arrays, :
`the same software also has been em- :
`ployed to lay out Fast Ethernet MA Cs :
`and other control logic requiring com- '
`plex signal paths and tight timing.
`
`A Peek Inside
`Examining the block diagram of the
`BCM3220 reveals the basic functions
`required to support full-duplex com(cid:173)
`munication using the MCNS protocol :
`(Fig. 2). Many complex functions have :
`been implemented plus encrypt/de- :
`
`crypt logic and a DMA-based, shared(cid:173)
`RAM host interface that has been op(cid:173)
`timized for Motorola's QUI CC series
`of680xx and PowerPC-based con(cid:173)
`trollers. To insure fast, efficient trans(cid:173)
`fers, incoming and outgoing Ethernet
`packets are exchanged whole-cloth in
`a single operation, with no buffer
`copying or other overhead-intensive
`intermediate steps.
`The downstream section of the
`BCM3220 interfaces directly with the
`BCM3116 QAM receiver. Since DOC(cid:173)
`SIS requires that data be encapsu(cid:173)
`lated within MPEG II transport
`streams, the MAC is responsible for
`extracting it before passing IP frames
`to the host system. Broadcom's de(cid:173)
`signers went the spec one better and
`included a n MPEG II filter port in
`
`To S~tisf y Even The Yer-·
`~ minally Paranoid, Two
`· Layers Of,Security Are
`P"roviJedl Within• DOCSIS,
`-~us A Fully_ Sh~e~ed_
`"Tunneling'' Protocol.
`' -
`
`their device. This feature allows the
`BCM3220 to be programmed to pass
`through selected MPEG video
`streams to an external decode
`cir cuit-
`a handy feature when de(cid:173)
`signing a
`combination cable
`modem/set-top box.
`In addition to recovering and pro(cid:173)
`cessing data, the downstream proces(cid:173)
`sor must perform decryption func(cid:173)
`tions and receive synchronization and
`control messages from the headend.
`These messages enable the headend to
`tell the modem to adjust its data rates
`and other parameters to match chang(cid:173)
`ing line conditions.
`To avoid conflicts in a shared-media
`environment, the MAC uses several
`tools to keep the modem synchronized
`with its neighbors and headend. First,
`the time-base recovery (TRC) func(cid:173)
`tion detects and interprets broadcast
`timing information. Since MCNS
`modems can be programmed for a va(cid:173)
`riety of data rates and transmission
`parameters, upstream channel de-
`
`scription (UCD) messages are used to
`tell the subscriber equipment what
`the headend is expecting to see.
`
`SPIOn Board
`Part of the BCM3220's job is to in(cid:173)
`terpret these messages and set the
`transmitter's modulation, timing, and
`FEC parameters accordingly. With
`this in mind, the MAC chip sports an
`industry-standard serial program.
`ming interface (SPI) bus master inter(cid:173)
`face which can be used to configure,
`and control both the QAM receiver(cid:173)
`and Burst modulator chips on the fly.
`If SPI-capable components are used
`elsewhere in the modem's design, the
`BCM3220 also can be programmed to
`set their operating values, such as
`tuner frequencies and amplifier gains.
`The chip's upstream processing sec(cid:173)
`tion is responsible for passing data to
`the headend. Interfacing directly to
`the BCM3037 QAM/QPSK modulator,
`it transmit s MPEG-encapsulated data
`within a series of time slots that it
`shares with the other modems in the
`network. To accomplish this task
`smoothly, it places requests to the
`headend during specially designated
`time periods.
`The BCM3220 MAC keeps these
`time periods straight by referring t o
`the upstream bandwidth availability
`map that the headend routinely broad(cid:173)
`casts. Stored in on-chip registers, this
`map tells the modem whe~ it can re(cid:173)
`quest an upstream time slot, transmit
`its data, or perform network mainte(cid:173)
`nance and management functions. For
`extended data transfers involving
`more than one block of data, the
`BCM3220 automatically requests a se(cid:173)
`ries of prescheduled piggyback time
`slots. This technique allows it to use a
`single transfer request to move niulti(cid:173)
`block files, increasing throughput and
`reducing access latency.
`
`Pretty Dam Good Privacy
`Of course, whenever you're using a
`broadcast media to transmit sensitive
`data, the issue of security always
`comes up. According to Tom Quigley,
`product manager at Broadcom, DOC(cid:173)
`SIS provides two grades of security at
`the hardware level. Both employ the
`date encryption standard (DES) algo(cid:173)
`rithm and Rivest, Shamir, and Adel(cid:173)
`man (RSA) key exchange. The real
`difference between the baseline and
`
`IPR2022-00246 Page 00007
`
`

`

`full security is the use of a highly se(cid:173)
`cure, r emovable hardwar e key for
`sensitive applications. In addition, full
`security uses the full authenticatioit
`protocol and a 1024-bit key to encrypt
`the exchange of traffic keys.
`The BCM3220 supports both levels
`of security. It performs the DES elec(cid:173)
`tronic-code-book (E CB) and cipher-(cid:173)
`block-chaining (CBC) functi ons in
`hardware, along with residual block
`termination (RBT). Normally, a 56-bit
`key is employed, although it can be
`programmed to run with a crippled 40-
`bit key for export applications. If de(cid:173)
`sired, the MAC chip also lets design.
`ers include application-based security
`measures for a third layer of end-to(cid:173)
`end prot ection (see "DOCSIS Secu.
`rity: Baseline Privacy," p. 74).
`The advent of the DOCS IS stan(cid:173)
`dard may prove to be a crucial turning
`point in the broadband wars between
`telephone and cable networks. While a
`shared-media system like cable will al(cid:173)
`ways be a less than optimal way to de(cid:173)
`liver data to homes, MCNS has done a
`very good job in making cable media
`as efficient, reliable, and secure as pos(cid:173)
`sible. For more information, contact
`the MCNS group at: Cable Labs, 400
`Centennial Parkway, L ouisville, CO
`80027; phone (303) 661-9100;fax (303)
`661-9199.
`
`Rambo's Uzi
`Broadcom's first silicon 1implemen
`tation of the DOCSIS st andar d will
`surely give rise to a first generation of
`low-cost, interoperable cable modems.
`Telco and xDSL advocates should not
`take this news lightly. Given the ag(cid:173)
`gressive nature of the cable industry,
`providing them with a standards-com(cid:173)
`pliant MAC chip like the BCM3220 will
`be like handing Rambo a loaded Uzi.
`
`PRICE AND AVAILABIIffl
`Available in sample quantities now, ~he
`B CM3220 will be in full production during
`the first quarter of 1998. Pricing f or the part'
`is $30 each, in quantities of 10,000.
`Broadcom Corp., 16251 Laguna Cany<Ylt
`R d., Irvine, CA 9261 8; (714) 450-8700; f a#
`(714) 450-8710; Internet: www.broadcom.com1
`CIRCLE 55
`
`How VALUABLE
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`SLIGHTLY
`
`CIRCLE
`552
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`substantial tax break and help
`send needy kids to college ·as well.
`
`Call for your free guide to learn how
`donating your slow moving inventory can
`mean a generous tax write off for your company.
`
`Call (708) 690-0010
`Peter Roskam
`Executive Director
`
`P.O. Box 3021. Glen Ellyn, IL 60138
`FAX (708) 690-0565
`
`Excess inventory today ... student opponuniry tomorrow
`
`IPR2022-00246 Page 00008
`
`