!\hstrnct
`The SWAP specification for wireless vnice and data 11clworking wilhin the home will enable a new class or mobile consumer devices that draw
`from the power and content of the Internet a11<.I tile Imme l 1C. If cahlc modems and xDSI, represent the "last 1nilc" access to the home, then
`[-IomcRf'"'s mission with SWAI' c,iuld he called the "very last 150 l'eel" within and around the home. IlomeRI' has lhc broad backing of the
`major corporal0 slakcholclcrs for nclworkin[\ within the home and is optimized specifically for the cosl/pcrformancc point needed for consumers.
`'!'Ile Lechnology lcvernges the existing PC-industry infrastrncturc around the Tnterncl, 'l'Cl'/11', and Elhernet, and adds a standard way lo connect
`ln the l'S'l'N for voice telephony. First prnducts should appear in late l 999, and future vcrsinns with enhanced features and/or higher data rates
`shm1lcl follow in one to two years.
`
`HomeRF: Wireless Networking for the
`Connected Home
`
`KEVIN J. NEGUS, PROXIM, INC.
`ADRIAN P. STEPHENS, SYMBIONICS, L'T'D.
`
`JIM LANSFORD, INTEL CORPORATION
`
`-,,-~;;i;~..,~-M---..:--... ··" ... '-....
`•
`i-i~ltn;~..ffi';,;::;ra;;;:_;;n-:~;r
`o HU\JOr factors arc present-
`ing a real opportunity at last for data networking within the
`home. The first is the explosive growth and usage of the I ntcr(cid:173)
`nct. The Internet clearly has the potential to revolutionize the
`delivery of information and entertainment to the home. The
`second factor is the cmcrget1cc of sub-$1000 powerful home
`PCs. With these low-cost devices tl1e barrier to getting on the
`Internet and discovering the utility of the PC is low enough to
`reach the vast majority of middle-income households.
`However, consumers soon find that the PC/lntcrncl com(cid:173)
`bination, although very compelling, lacks some key
`attributes in terms of mobility and convenience n[ location
`compared with many of their traditional information and
`entertainment options such as newspapers, magazines, TV ,
`videos, FM radio, CD/stereo, and so on. The powerful home
`PCs (and the printers and peripherals attached to them)
`often end up turned off 20- 22 homs a day while tucked into
`a bedroom or den corner where access is possible only with (cid:173)
`in a 2- J fl "lrnhhlc." The major opportunity fur networking
`in the home is thus In extend the reach of the PC and Inter(cid:173)
`net throughout the home and yard, and connect the
`resources uf the PC and Internet with legacy home applica(cid:173)
`tions such as telephony, audio entertainment, and home
`control systems. Another opportunity is the sharing of
`resources (such as an lntcrnct gateway ur high-quality print(cid:173)
`er) among PCs in multi -PC homes.
`With these issues in mind, several major stakeholders in .
`the home PC industry formed the Home RF Wmking Group
`(or " llomeRfl") in early 1997. The key goal of the group was
`and remains to enable interoperable wireless voice and dat a
`networking within the home at consumer price points. Homc(cid:173)
`Rfl started hy pooling market resi;arch from the memhcr
`companies to produce a Market Requirements Document.
`This document guided the technical proposals within th e
`group, and with tremendous cooperation from major stake(cid:173)
`holders in the RP communications industry and the nascent
`wireless LAN comrm111ity, the Shared Wireless /\cccss l'mto(cid:173)
`col (SW Al') was created. llorncRF is now in the process of
`bringing the SWAP specification to its final released Form.
`
`This is proceeding vety quickly due to the native support with(cid:173)
`in SW/\l' for 'l'CJ>/11' nctwmking and Internet access, and for
`voice telephony via the public switched telephone network
`(l'STN), or voice over Tl'. SWAP achieved support for these
`important network stacks easily by reusing major sections of
`proven RF protocols and then simplifying them where appro(cid:173)
`priate for home usage.
`Today the IInmeRl-' organization consists of approximately
`100 members representing the hulk of the PC, telecommuni(cid:173)
`cations, and consumer electronics industries. General infor(cid:173)
`mation on the organization is available at http://www.
`homcrf.org. The specification described in this article started
`at Revision O.l from a proposal made in late 1997, and was
`approved and published as Revision 1.0 in January 1999, As
`of this writing, the Revision l.2 specification is available,
`which includes methods of bridging between a Home RF net(cid:173)
`work and wired networks such as Home Phonclinc Network(cid:173)
`ing Alliance (llomcPNA) and Ethernet.
`Vision and Applications
`llomeRF secs SWAP as one of several connectivity options for
`the home of the future. The relationship of SWAP with other
`connect inn options is shown in Fig. 1. In this scenario, the main
`home PC is linked somehow to an Internet gateway that might
`be a 56K, digital suhscrihcr line (xDSL), or cable modem. This
`link may be a simple cable, a wired network connection, or
`even a SWAP network connection. This main home PC would
`likely have a variety nf built-in or peripheral resources such as a
`printer, a scanner, a CD drive, a DVD drive, and so forth. For
`most home PCs today and looking forward, USB wonk! be the
`bus or choice for many peripherals that do 1101 need to he
`mobile or remote from the home PC. For video applications
`such as connecting camcorders, IEEUIJ94 is the expected
`choice, and there arc 110 viable RF alternatives at consumer
`price points al this lime (although VFlR al ·16 Mills is a reason(cid:173)
`able " no-cable" choice). HnmcRF also expects that other net(cid:173)
`working choices will also he viable for sharing resources among
`multiple PCs, as shown in Pig, I, These options include convcn-
`
`20
`
`1070-9916/00/$10.00 @ 2(1()() rF.F.F.
`
`11 \EF. Personal Cu111111uniealions • February 2000
`
`Page 1 of 8
`
`EXHIBIT 1006
`
`

`

`- - - - - - ---- -
`
`Cable modem
`
`56K
`
`xDSL
`
`,, .. ,~~L
`. gateway __ j
`
`(}; <I',
`
`CID
`• w . .i j ~ . """"
`
`periphera ls
`
`remote devices
`
`. ..
`
`Main home PC
`
`call e r's nam e on a ny give n h and se t.
`Por out bo und c a l ls, the PC cou ld
`intcrprnt a spoke n des tin a ti on name
`( i. e., "Ca ll Mom ") tlmn1 g h voice
`recognition , and t he n based o n
`date/time determine the like ly mtmhcr
`for lhc person and ro ut e lhc call using
`the lowest-cost approach (which mi ght
`be II' lekphnny). The handse t co uld
`be used to pick up vo ice mail se k:clcd
`hy the use r from th e home PC c all
`center. With voice synthesis the ha nd(cid:173)
`set co uld also he used lo " liste n" toe(cid:173)
`mail. With more so phisti cati.:d
`a11plication software , th e h andse t
`coul d ac hieve l'IM functiona lity by
`usin g voice or keypad 1/0 to store lists
`(i. e., '' Add ;l quart s o[ milk to my
`shoppin g I isl") or co n l rnl honw
`automation rca turcs ( i. e., "Turn Lhc
`tcmpcratun.: up 3 d eg rees") . All or
`the se and undoubt ed ly mnch more
`crea tive features arc poss ibl e because
`of th e standa rd interopi.:rahlc me th od
`ol' c unn i.:c litt g to the hom e l'C . The
`cordless hand se ts themselv es arc
`slightly cli lTe rc nt, but not substanlially
`more complex or e xpensive, than the
`exisl ing " dumb " co rdl ess h a nds e ts
`sole! in multimillion uni t volume today.
`i\ second interestin g example is a
`mobi le viewer appliance. This could take many form s, but fun (cid:173)
`dam e ntall y consists of a color LC D di sp lay ( like th at o[ a
`notebook co mputer) with some limilcd input device (e. g., a
`pe n) and a SW i\l' radio network co11ncction. Such a dev ice
`could he c ithi.:r an exte nsion or the home l'C (like an X-lenni-
`11al) or si mply a Wch browsi ng ex te nsion of a n Inte rn et gate(cid:173)
`way. In e ith er case the viewer communicates e ntire ly through
`receiv ing and sendi ng TCP/ I I' packets.
`The third of many potenti al applications is resource sha r(cid:173)
`ing amon g multipl e !'Cs in th e sa me lwmi.:. Th e resource tu
`he shared could be a high-quality printi.:r, a backup storage
`devici;, or an Int ern et co nnection. i\nothcr possibility for this
`is multiplayer ga ming. Clea rly these resource-sha ring appli ca (cid:173)
`tions have rece ived considc rahl i.: a ttention from other homc(cid:173)
`wi ring-h ased allcrnalivcs to networking. It is impor ta nt to
`note that th e market for f-lom c RF is not stri ctly multi-PC
`hom es. i\n y hom e with a mod e rn hom e PC or a n Internet
`ga teway is a ca ndidate for com pe lling portabl e d ev ices
`enabled hy the SW i\l' specification.
`Network Topology
`Th i.: SW i\l' architecture is a uniqu e combi nation of a man (cid:173)
`aged network that provides isochro nous services sucl1 as inte r(cid:173)
`active voice, and an ad hoc peer-to-peer network lh at provides
`traditional data networking. T he protocol has been optimize d
`to provide the kinds of services mosl needed rrom unlcthcrcd
`dev ices in th e hom i.: . Three kinds o r d ev ices ca n be in a
`SWAP network:
`• A connection point (Cl'), which acts as thi.: gateway between
`the pe rso nal co mputer , PST N, and SW i\ l'- co mp a tihlc
`devices
`• Voice devices (isochronous data d ev ices, also ca ll e d 1-
`nodcs)
`• Asynchronous data devices, also call ed !\.-nodes
`The co ntrol point is usually conncctcd to the main hom e
`
`Other home networks
`(Eth ernet, phone, AC)
`
`Isochronous ·clients
`
`■ figure ·1. Hie SWA I' vision for home netwmki11g.
`
`tional IO/ IOOUaseT Ethernet, hom e phone line Ethernet, and
`AC power line networking. Th e last option is particularly well
`suit ed for many home automation scenarios where ve ry low
`data rates arc acceptable.
`The SWAP networking vision is also apparent in H g. I. The
`I-JomcRF technology supports both isochronous clients that arc
`slaves to the main hom e PC and an asynchronous network or
`pee r dev ices which is effective ly a wireless EtlH.:rn e t. In most
`cases the system starts with a control point, usually connected
`to 1111.: main home l'C via USB. ' i'his control point is not abso(cid:173)
`lutely necessary for devices in th e asynchronous ne twork of l 1ig.
`I, hut even in that case it offers some inte resting power saving
`options fur ultra-portahlc devices, as will be descrihetl in lhe
`medium acci.:ss control (Mi\C) overview later. The isochronous
`clients, s uch as cord less tcli.:phoncs, wirnlcss hea dse ts, or
`remote T/ 0 dev ices lo the hom e PC (a co ns umer pe rsonal
`inform a tion manager, PlM), arc a lways ho und to the control
`point, which assigns them guaranteed bandwidth for hounded
`latency communication. The asynchronous peers can also com(cid:173)
`municate to the main home PC as with any other peer dev ice.
`Nole that data transfer on the asynchronous ne twork between
`a ny two peers is directly tu each o ther as opposed to routed
`through the control point. Consider nnw thrci.: major applica(cid:173)
`tions for the Homc RF technology.
`Th e fir st exam ple is PC -e nhanced cordless telephony.
`Today th e re ar c no sta nd ards-h ase d di gital cordli.:ss tele(cid:173)
`p hones fur consumer use in the United States where intc rop(cid:173)
`crahility of mul tiple vendors is e nabled. Homc RF defines a
`new sta nd a rd for interoperable digital cordless tclcphnncs
`hoth in th e United Sta tes a nd globally. Furthcrmmc, the
`SWAP speci[icatiun includes a sta ndard method for connect(cid:173)
`ing the cordless tdcphonc to the home l'C softwat·e applica(cid:173)
`tions. Thu s, many n ew e nhanced fea tures arc possibl e. For
`exampl e, ca ller ID information could be sent to a l'C applica(cid:173)
`tion to look up the caller's nam e and then route the call to an
`indivi du a l handse t (rather than number ) and display the
`
`IEEE l'crsonal Communicat ions • February 2[XJO
`
`2 1
`
`Page 2 of 8
`
`EXHIBIT 1006
`
`

`

`l'C, typically via USB. lt may also have a connection to the
`PSTN. It is capable of performing data transfers to and from
`other data devices using an asynchronous contention-based
`protocol. The control point manages the network to provide
`priority access to the radio medium for isochronous devices.
`Thus, the SWAP protocol is a hybrid in several ways; it is
`client-server hctwccn the control point and voice devices, but
`peer-to-peer between data devices. The interactive voice
`transactions arc circuit-switched, time-division multiple access
`(TDM/\), hut the asynchronous transactions arc packct(cid:173)
`switchcd, carrier sense multiple access (CSMA). It is precisely
`this richness that gives SWAP the capability to be broadly
`used in the home; it is not designed to support hundreds of
`users doing similar things in an enterprise, hut rather the vari(cid:173)
`ety of applications that occur in a residential setting. There
`arc several usage scenarios the SWAP protocol was designed
`to support; these focus on the exchange of voice and data by
`portable devices within the home environment. Typical uses
`the network was designed to support include:
`• A busy family
`- Three children play interactive PC games with each other
`from their rooms. They can talk to each other through their
`PCs.
`- Mom is in the kitchen listening to her phone messages
`recorded by the PC answering machine application.
`- Dad is in the garage completing an oil change. He enters
`the data into lhe car maintenance log he maintains on his
`PC into the display pad.
`• A montage of voice applications
`- Mom is using her personal handset to record a message for
`the kids to listen to when they return from school,
`-Dad is asking for stock qLJOlcs from the Internet and get(cid:173)
`ting a vocalized response through a text to speech (TTS)
`engine.
`
`Voice traffic can also be ,ictive
`
`TDMA
`I node
`
`CSMA
`A node
`
`PSTN
`
`CSMA
`A node
`
`■ l'igure 2. SWA l' network topoloffY flexibility.
`
`-Dad checks the temperature in the garage and turns ou a
`space heater via voice commands.
`-Uncle Ed listens to a soccer match broadcast via audio
`over the Web to his wireless headset on the front porch.
`• A montage of display applications
`- Mom pulls up a recipe from the PC and adds oregano to
`the shopping list.
`- Dad updates the family financial portfolio.
`- Junior plays Tctris.
`- Daughter reads the latest onlinc issue of Teen magazine.
`Figure 2 shows an example of a typical SWAP network
`consisting of two A-nodes, one I-node, and a CP. One of the
`A-nodes is a power managed display pad whose communica(cid:173)
`tions traffic is managed hy the PC so that it can maximize bat(cid:173)
`tery life. Although not shown in this figure , the laptop A-node
`could also be power managed. As tl1is figure shows, SWAP
`has a unique ability among networking protocols to mix
`intense, high-demand packet traffic with infrequent command
`and control traffic and with high-quality voice traffic. The per(cid:173)
`sonal computer is an integral part of the SWAP system,
`although peer-to-peer data networking is available even when
`the PC is inoperative.
`Software Architecture for the PC
`SWAP asynchronous data devices will be supported in
`Microsoft Windows via the NDIS driver library. The NDIS
`library performs many of the functions common to all net(cid:173)
`working device drivers, such as synchroni;-:ation, and also pro(cid:173)
`vides a standard interface for higher-level applications to
`access. Manufacturers of network adapters arc only required
`to produce a miniport driver that provides functionality specif(cid:173)
`ic to their hardware. Miniports of a given media type can be
`used with higher-level protocols knowledgeable about that
`media type with no further 111ndifications,
`as shown in Fig. 3, where the shaded hlocks
`arc provided by the operating system.
`Hardware manufacturers producing A(cid:173)
`node devices should write a connectionless
`mini port that declares itself a member of the
`Ethernet media type. To higher-level proto(cid:173)
`cols, SW /\P A-nodes will be indistinguishable
`from regular Ethernet adapters, allowing
`Ethernet-knowledgeable applications to
`immediately function with SWAP devices.
`Hardware manufacturers producing
`isochronous Cl' devices should write a
`device driver that provides a TAl'I inter(cid:173)
`face. TAPI is a simple, generic set of
`objects, intc1-faccs, and methods for estab(cid:173)
`lishing connections between devices; TAPI
`communicates with the CI' via a TAPI ser(cid:173)
`vice provider. TAP! applications will he
`able to set up, control, and take down calls
`on SWAP devices via the TAP! interface
`(Table l).
`Some device designers may wish to
`stream voice conversations between the
`SWAP adapter and another adapter within
`the PC in real time. An example scenario
`would be that of a voice conversation
`between the SWAP adapter (i.e., a user
`with a SWAP handset communicating with
`the SW /\P adapter) and another adapter in
`the PC (e.g., a modem attached to a phone
`line or a sound ca rd attached to speakers
`and a microphone). In Windows 2000 and
`
`22
`
`IEEE Personal Co111m11nications • I'chruary 2000
`
`Page 3 of 8
`
`EXHIBIT 1006
`
`

`

`. - -
`
`-~ - - - - - - - - - - - - - - - - - -
`
`· :_ ~lnW~{§~·:.i:1 A~iiA~~i{qoi~s~·rbl~l~~:ri\q~lfa~?'.n.tr:Jf;i?~Mt~t~~.9bi~Jt~Jli't mi
`
`:l~lil1llli~itilll!! :'.!J
`
`\::. !~Pl} :?=~-~r-~~fl?r~l-?t~?\c;:.e\;~~f~~:~'.
`. ,,,..
`_.,. ,_,
`~==~~·
`~- - .u-----• ••••••••••••-•••-• •-•-•••••••••-••••.•,-··
`.. - • •.•• •.· : .. •
`■ T,1ble 1. SWII P dri~er architecturesfbr recent Micmsojt opemti11i ,lystems.
`
`98, voice data can he streamed between adapters
`via the DirectS how streaming architecture./\
`DirectShow filter graph is plumbed frolll the data
`source (in this case, the SW/\1' ada pter) to th e
`data sink (the modem or sound card) . The Media
`Service Provider (MSP) interface provid ed by
`TAI'] 3.0 enabl es the application to control and
`access the Direct Show voice data strealll.
`The MAC Overview
`The SWAP MA C has bee n optillli zed for t he
`home environment anti is designed to carry both
`vo ice and data traffic and interoperate with the
`PSTN us in g a su bse t of t he D igi tal Enhanced Cordl ess
`Telecommunications (DRCT) standard, a digital cordless tele(cid:173)
`phone standard used in res ide ntial appl ica ti o ns throughout
`Europe. The M/\C is designed for use with a fr eq uency- hop(cid:173)
`ping radio and includes a TOMA service to support the del iv(cid:173)
`ery of isochronous data (e.g. interactive voice) , and a CSMA
`with collision avo idance (CSM/\/C/\) service derived from
`wireless 1,/\N standards such as ll i l-:l •:802.-i-l and Opcn/\ir to
`support the delivery of asynchronous data. The SWAP MAC
`provides the following fea tures:
`• Good support for voice and data by using both 1'DMA and
`CSMA/CA access mechanisms
`
`• Support for four high-quality voice conn ection s with :l2 kh/s
`adaptive differential pulse code modulation (/\ DPCM)
`• 1 figh data lh rn11gh p11t or 1.6 Mb/s
`• Data security - None/basic/rolrnst levels of encryption
`• Power management for both isochronous and asynchronous
`nodes
`• 24-bi t network ID
`The MA C protocol uses a supcrframc as illustra ted in Fig.
`4, which inco rporates two con tention-free periods (Cf'Ps) and
`a contention period. The sta rt of the superfrarn e is the point
`at which a statio n begins to hop to a new chan ne l and en ds
`immediately heforc the stat ion starts to l1op to the next cl1an(cid:173)
`nel. The duration of the sup crfralll e is fixed and is the sa me
`as the dwell or hop period. The access mcclurnism used dur(cid:173)
`ing each CFP is TDMA, while the access mechanism used
`during the contention period is CSMA/CA.
`Each CFP is divided into a number of pairs of fixed-Jcngth
`slots, two per voice connection . The ffrst slot in eac h pair is
`used to tra nsm it voice data from the Cl' to a node (downlink),
`and the second is used to transmit vo ice data from a nod e to
`the CP (uplink). In a managed network a beacon is transmit(cid:173)
`ted immediately after the hop. T his beacon is used lo main(cid:173)
`tain ne two rk sy nchroni za tion , cont rol the for mat of th e
`supcrframc, and manage when each node should transmit and
`receive data.
`CF1'2 at the end of the supcrframc is us ed for th e initial
`transmission of the voice data, while Cl-'1'1 at the start of the
`sup c rframe is used for the optional retransmission of any
`data which was not received or in co rrec tl y received in th e
`previous dwell. The dwell period is fixed at 211 ms to provide
`acceptable performance with respect to latency. The length of
`the dwell period also mea ns that eac h voice data message
`contains 20 ms of AD PCM data (641l bits), eq uivalent to an
`extcntlctl DECT ll-field, a11d 56 bits of control data, equ iva (cid:173)
`lent to the DF.CT A-field plus sollle additional address ing
`infor lllat ion. With a 2ll ms supcrrram e the MAC ca n provide
`fo ur vo ice conn ectio ns with a large enough CFP at the start
`of th e fra me lo enable up to four retransmissions to be
`accommod ated.
`CF P2, in wh ich initial trnnsm issio11 occ urs, and CF1'1 , in
`which retransmission occurs, arc separated by a frequency
`hop, giv ing frequency and time diversity, which is particularly
`importa nt given the potentially noi sy cnv irn nm cnt in which
`the protocol operates. At the end o[ c 11p·I in the supcrfra mc
`there is a space reserved for a service slot which is used hy
`voice nodes to request connections from the Cl'. Each vo ice
`data packet tra nsmitted by a nod e in c lud es in the packet
`header a piggyback acknowledgment of the last voice dat a
`message received hy t he nod e. That is, in the uplink packet,
`the voice node acknowledges the down link packet se nt hy the
`CP. T hi s sys te m a llows the C l' to dcterllline prior to a hop
`which vo ice data transmissions we re lost, detcrrni11c the
`retransmissions required, and advertise these retran smi ss ions
`
`· · ::~ttfi&iK~~i;,~~\~~~:~~if~~?i~~~~~1it~~,;:'..:.
`l'tI}l~i.~~~·:(~~.1. ~1}~ijl~1K:~:~~: p'.is~~pt:\l l::~;,;6i_ber;,·~'.::I
`· l~:·1•i~~i~.~;;.'.~:"~~~,~::}~:; >·;~ ~~o,{:,;'~:.i:·~':·:·;c::~s.:: ',:} ~/~ 1
`
`.. ~I _____ c_o_n_n_e_c_ti_on_l_e_s_s_m_ in_ip_o_r_t _d~riv_e_r _ ___ _......,
`
`SWAP-CA-aware
`TAPI 3.0 application
`
`(a)
`
`+
`.TAPI 3.0
`. TSPI
`
`TAPI 3. 0
`
`*
`
`TAPI
`
`+
`
`TAPI 3.0
`MSPI
`
`(b)
`
`■ rigurc 3. a) SWA/' A -node driver architecture; h) SWAP f .
`node driver 111d1itecture.
`
`IEEE Pcrslmal C,11mnunicalio11s • r chruary 2000
`
`23
`
`Page 4 of 8
`
`EXHIBIT 1006
`
`

`

`CFP2
`Hop
`-----------►-
`
`01
`
`U4
`
`U3
`
`U-2
`
`◄-Connection 1
`
`....
`
`Uplink
`
`"''
`
`-2 ''".'" . · .... ·•.
`
`- _ contention peric,d - __ ...
`cSMAICA· ai:_c.ess ·mech·arism·
`--= -~~--~~-~ ~-_...,
`Superframe
`
`Ret ran smission 1
`
`B: Beacon
`Dn: Downlink slot
`Un: Uplink slot
`.
`CFP1 : Con tains two slots per connection for data that requires retransmbsion
`CFP2: Contains two slots per connection, one for downlink data and the other for uplink data
`
`■ rigure 4. A SWAJ'ji-ame description.
`
`in the beacon at th e star( or th e next s1q1crframe; each voice
`data packet ca n only be rctransmitled once.
`For data traffic a CS MA/CA access m echani sm is used
`during th e contention period of th e superframe. With this
`scheme, the protocol provides efficie nt data bandwidth even
`wi th concur rent active voice calls and microwave oven inter(cid:173)
`fere nce. Pea k effective user thrnughpnts or over l Mb/s arc
`possihlc under lightly loaded conditions in the 1.6 Mh/s 4-fre(cid:173)
`qu e ncy s hift key ing (FSK) mode. r.urth c rmorn, data transfer
`rates of lrnndrcds of kilo bits ric r second ca n occur even with
`four voice calls active simulta neously,
`The CSMA/C,\ mechanism is similar to Ethernet (802.3),
`e nablin g easy integration with a n exist ing TCP/IP protocol
`si-ack within a ho st platform; the main dil'fc rc ncc with Ethe r(cid:173)
`ne t is the slotted contention mechanism and the addition of
`MAC-level ack nowledgment of uni<:ast packets. Figure 5 illus(cid:173)
`trates how the med ium is accessed during the contention peri(cid:173)
`od.
`Th e CSMA/CA access procedure is designed to provid e
`fair access to the medium to a ll nod es by ,tsing a contention
`wi nclow a nd hackofl' co unter, as shown in Fig. 4. llc l"orc any
`node transmi ts a packet it selects a backoff counter (a number
`of contention slots) and then starts li sten ing. Wl1en the medi (cid:173)
`um has bee n clear for a DU'S period it decrements its hackoff
`co un te r for each free co nt e n t ion slot. Wh e n th e bac ko ff
`counte r expires the n ode transmits the mess age, Whenever
`t he medium is busy the cou ntdown is suspended and only
`resumes when th e medium has Il ee n fr ee for a DIPS . This
`baclcoff mecha nism red uces t he probability of rnllisiun, and
`pe ,:ro rmin g a lrn cko ll befo re transmi ss ion also ens ures that
`responses from multipl e nodes responding to a brnadcast mes(cid:173)
`sage on an otherwise idl e network do not all collid e , If a
`retransmission is requi red because of a collision or transmis;
`
`sion failure, lite size of the collision window is incrnasecl from
`an initi al va lue of 8 expo ne ntially up to a m aximum G4 to
`avoid congestion.
`If there is no CP present, the data nodes can create an ad
`hoc network in which control of th e network is distrihuted
`betwee n all the nodes . The primary function of the beacon is
`to enable all nod es to synchronize to the hoppin g pattern of
`the network. The beacon tra nsmitted hy the CP is also used to
`manage the network during the Cf'l's. Th e CP beacon (C PU)
`can include a list of active voice connections (and therefore
`slot assignments), retransmission slot assignments for the cur(cid:173)
`rent su pe rfra me, connection s tatus informat ion, aml paging
`information. The C\'13 ca n also provide powe r manageme nt
`for isochronous and asynchronou s nodes to maximize the bat(cid:173)
`tery life of portable devices.
`Th e pro cedure for power management of isochronous
`nod es is strai ghtfo rward. l n t hi s pro cess , clt, r ing an active
`connecti on (e.g., a voice ca ll) the isochro nous nodes power
`on, initially only for the duration of the CPB, to receive slot
`assignment in for mation. T hey th e n power down un ti l their
`assigned slots a rc du e. When not in a n active connecti o n
`state, iso c h ro nous nod es need only pow e r- up every N
`dwell s, wh ere N is chosen by the syste m des igne r accord in g
`to t he application be in g supported, and as a co mpromise
`between powe r-sav ing and speed of response to a n ew con(cid:173)
`nection.
`Th e CP also provides power manage me nt services for
`async hronous nude s, Fi g ur e 6 illu strat es th e process [o r
`sending broad cast messages to power -saving asynchronous
`nod es (PS-nudes), which is d escribed as follows. Th e C P
`maintain s a countdown to the next dwell w he n PS-nod es
`should wake up, which is bro adcas t in th e Cl'll. In ste p 1,
`PS- node 3 powers up and receives the "dwells-to -hroacl cast"
`
`Slot 2
`
`SIFS ~ 142 flS
`Slot time = 167 ftS
`DIFS "' 309 fl S
`
`~--►
`
`StFS
`
`• Sender selects a slot (backoff counter) and then decrements the counter while the medium is clear.
`• Medium must b e free for a DIFS peri od before th e backoff counter is decremented.
`• Th is exa mple shows transmission of a packet in slot 5.
`·
`
`■ rigure 5. The CSM/1 medium access procedure.
`
`24
`
`IEEE Personal Cmnmunications • f.cbruary 2000
`
`Page 5 of 8
`
`EXHIBIT 1006
`
`

`

`C~-c:,:~~t,o~- -~ - - -
`· /--->--.
`------------
`·-
`·,,
`Step 5
`- •• •
`' - ..•
`CP rebroadcasts '·-.
`
`pornt
`
`:1(
`, '
`CP buffers broadcast
`
`►
`\
`
`Step 4
`PS-node wakes up
`to receive broadcast
`
`Step 1
`PS-node wakes up to check
`' dwells-to-wakeup"
`
`~
`
`m
`
`Hop {{; 1--~-B-P-. ~----;
`,_,,,:.-.
`,;;;
`#1
`
`Dwells to
`broadca st -► 3
`wakeup
`
`►-
`
`2
`
`n - 1
`
`Step 2 \
`
`----~
`----.....
`________ . _.-----
`
`.
`. Node 1 broadcasts )
`and is recorded by CP.
`
`(
`
`Step 3
`
`. Power-saving node 3 )
`receives node 1 and 2
`rebroadcasts from CP
`
`------~--."- ·• ----------
`
`■ rigurc (,. l'ower manaxernent of' C'SMA nodris j'or /Jmadcast messages.
`
`counter. The maximum value of the dwells-ID-broadcast
`counter is system-design-dependent, allowing the des ig ner
`to trade off latency, CP buffer size, and broadcast reliability
`against battery lil'c . Node l transmits a broad cas t message,
`which is received and stored by the Cl'. Node 2 transmits a
`broad cast message, which is received and stored by the Cl'.
`Th e PS-node wakes up when its dwell counter clccrcmenls
`lo O (step 4). The Cl' transmits the buffe red broadcast mes(cid:173)
`sages during the dwell (step .'i) . The PS-node recei ves the
`hroadcasl messages (step 6) and then goes ha ck lo standby
`mode.
`Figmc 7 illustra tes the process !'or sending unicast mes (cid:173)
`sages to power-savin g asynchronous nod es. The PS -node is
`
`controlled hy a "wake- up" flag transmitted in the CPU. This
`flag is activated by a re(Juest: from th,; sending node. Tims, in
`this example th e I'S -node wakes up and listens for a wake-up
`fla g in the CPI\ (step I). Since th e lfag is not set, it powers
`down. In step 2, node I transmits a request to the Cl' to wake
`up the I'S-node. In ste p 3 the Cl' asserts the wake-up fla g in
`lhe CPI3. Some time later (dependent on the designer's trade(cid:173)
`off of power-saving versus latency) the I'S-node wakes up and
`receives the wake-up i'lag (step #4). The PS-node and node ·1
`transfer data using the normal CSM/\/CJ\ access me thod
`(step 5). The PS-node powers-down a time al'ter the l'inal mes(cid:173)
`sage exchange (step fi).
`
`------·-··----:------
`
`(
`,I
`
`Connection point )
`----:.__ _______ ___
`
`Step 3
`CP sets "wake-up" flag and
`node address
`
`Step 4
`PS-node wakes up, hears
`, . "wake-up" so stays switched
`on
`
`Step 1
`PS -node wakes up doesn't
`hear "wake-up'
`so switches off
`~
`
`CPS
`REQ
`
`Sender hears
`PS -node
`wake-up
`--- .,.,-:: 7
`--. -
`
`/
`
`,
`
`/
`··., -.,"-·
`
`'
`
`Step 2
`Sender asks CP
`to wake-up PS-
`node
`
`L __ . c-~~,~~:s / e::-;,:=)
`
`----- _,,,_.. ___ --
`, ;:, '
`\
`St~p.5
`Sende,: and PS\node
`\
`transfer ,~ata
`\
`' ,
`
`------· -,. ----
`
`■ figure 7. l'ower rnana1:emeru of CSMA nodes j'or unicast messages.
`
`IEl ~fi Personal Communir.:ations • Fehruary21Hl0
`
`2:.
`
`Page 6 of 8
`
`EXHIBIT 1006
`
`

`

`- - - - - - - -- - - - - - - - - - - -
`
`T
`■ rigurc ll. l'artilio11ing of f?F modem and dif:ila l MAC componen t sections.
`
`channel filtering s peci fi ca tion causes dra(cid:173)
`mati ca lly less intc rsymhol inte rference due
`to filtei- group delay variation s in the pass(cid:173)
`band. /\nd third , the SW !\I' packet headcrn
`for 4-FSK add a spec ial training sequence
`to allow o ptimum slicing threshold va lu es to
`be determined for the changing propagation
`cnvirn nm e nt. Th us, for us age within most
`homes, the 1.6 Mb/s data rate is 1·cally avail(cid:173)
`able with SWAP and acids virtually no cost
`to the 0.8 Mb/s solution.
`Although the hoppin g tim e is easy to
`meet, the transceiver turna round tim e cre(cid:173)
`ates a chall e nge for many co nve ntio nal RF
`transceiver a rchitect ures and components.
`This low transceiver turnaround limit is
`essen tia l for SWJ\P lo provide low-lat ency
`per[orma ncc in a mixed voice and data net(cid:173)
`work in the presence of microwave ovens and other interfer (cid:173)
`ence sources. l'ortunatcly, increasing levels of integration a nd
`speed in com ple me ntary metal oxide semi w nductor (CMOS)
`circu its now make it possible to huild very fast switching chan(cid:173)
`nel synthes izers capabl e of this requirem ent hy adapting tech(cid:173)
`nology previously used in precision instrumentation .
`In fact, the entire SWAP PHY specifi cation has bee n writ(cid:173)
`ten speci fica lly to accommodate very-low-cost singlc-cltip
`impl emen tat ion in CMOS technology. A typical system parti (cid:173)
`t ionin g is shown in Fig. 8. For many of the digital d ev ices
`envisioned hy HomcH.F, the digital MAC bascb,md portion of
`the component solution can he integrated into a large applica(cid:173)
`tion-specific; integrated circu it (/\SlC) already in th e device.
`At -30K ga tes fo r the SWAP data core, this is extremely low
`cost in the sub-0.25 run CMOS era. The modem function ality
`can interface to the digit a l baseband via a very simple serial
`in terface (with no analog quantities). Th e modem and RF
`function a lity can all be integrated into a single mi xed -signal
`CMOS IC as shown because of the specific technical require(cid:173)
`me nts on filtering and modulation chosen by TlomclU1. Note
`that it probably docs not make se n se to inte grate the RF
`front -end functionality, such as the low-noi se amplifier, powe r
`amplifier (if present), antenna switches, and band-select filter,
`o nt