ISDN Basic Access Components Design ISDN Peripherals ABSTRACT Int

The Datasheet Archive - 100 Million Datasheets from 7500 Manufacturers.

ISDN Basic Access Components Design ISDN Peripherals ABSTRACT Int

Datasheet Thumbnail

Top Searches for this datasheet

ISDN Basic Access Components Design ISDN Peripherals
ISDN Basic Access Components Design ISDN Peripherals
ABSTRACT Integrated Services Digital Network (ISDN) customer premise equipment been readily available mainly because lack services across ISDN islands lack ISDN connection over ``last mile'' subscribers home their part Central Office switch manufacturers have recently demonstrated inter-working services across wide geographical areas Also semiconductor vendors have produced VLSI transmission devices allow field trials ISDN services subscribers home basic components building ISDN peripherals (VLSI components signaling software modules data communciation modules) have been demonstrated early equipment used field trials next phase develop ISDN products that cost competitive with present equipment (analog phones MODEMs) which attempting offer similar services using older technologies order protect investments inter-working Non-ISDN equipment Feature phones machines Personal computers) with ISDN equipment essential foreseeable future INTRODUCTION ISDN provides integrated services voice non-voice applications over end-to-end digital network main objectives ISDN's User-to-Network Interface (UNI) following provide access wide range services support universal portable terminals provide cost effective connection digital network Until recently interfaces were defined Basic Rate Interface Primary Rate Interface these part Narrow-band ISDN (N-ISDN) Recently Broad-band ISDN (B-ISDN) standards being defined multi-megabit transmission rates standards appear follow similar reference model N-ISDN B-ISDN beyond scope this paper Both Basic Primary interfaces B-(Bearer) channels D-(Delta) channels B-channel kilobit-persecond circuit switched channel used voice data D-channel message-based (for BRI) (for PRI) channel used signaling packet switched data standards defined terms layered protocol based Open System Interface (OSI) reference model International Standards Organization (ISO)
National Semiconductor Application Note Paripatyadar December 1991
Layer physcial layer defines electrical mechanical characteristics also includes channel structure line coding cable configuration Layer data link layer's function provide error free link upper layers protocol Link Access Procedure D-channel (LAPD) been standardized Other similar procedures exist B-channel operation layer protocol D-channel carries either signaling data information thorough understanding basic standards basic service capabilities related User-to-Network Interface (UNI) essential developing equipment this market protocol standards physical layer components Basic Rate Access discussed design concepts ISDN peripherals using these components developed most common ISDN equipment ISDN phones Terminal Adapters (stand-alone based) units Repeaters protocols data communication outlined ISDN hardware technology Analog Pairgain market explored Finally interworking todays analog equipment such Feature phones machines with ISDN equipment explained REFERENCE POINTS Standard configurations have been defined They contain reference points indicated Figure standards have been defined compatibility these reference points Existing interface specification covering standards such RS232c ISDN terminal terminal adapter interface characterized four wires user rate line rate (including overhead) physical terminals passive network Normally T-reference point same reference point Basic access however optional network termination (NT2) provided basic access some differences possible This interface characterized point-to-point network wires user rate Kbaud (including overhead)
AN-796
C1995 National Semiconductor Corporation
11270
RRD-B30M75 Printed
11270
ISDN terminal equipment Existing terminal equipment VT100 ISDN terminal adapter adapts existing terminals ISDN Network terminating equipment converts loop transmission interface interface Additional network termination example convert primary rate access basic rate access Line Terminator local telephone exchange
FIGURE ISDN Basic Rate Interface Reference Points CAPABILITIES access capabilities typical examples their follows
D-channel signaling user data D-channel signaling B-channel voice data
ISDN phone
11270
Point-to-Point
D-channel signaling B-channels
voice data Voice Data terminal B-channels carry user-information such circuit-switched voice end-to-end data form that ends understand D-channel used signaling channel between terminal network equipment used setting calls allocating B-channels terminating calls forth using layered LAPD protocol addition signaling D-channel also carry speed packet switched data Terminal Adapters designed handle user data over D-channel could provide cost effective MODEM replacement solution ISDN world Applications D-channel data will include transaction-oriented messages transmitting information from personal identity cards telemetering data Unlike B-channels packet switched data D-channels multiplexed providing multiple logical channels packet switched calls from end-user INTERFACE CHARACTERISTICS basic rate interface interface offers point-topoint multi-point network configurations illustrated Figure multi-point network called passive terminals attached Network Terminator Unit (NT1 Line card)
11270
Short Passive
11270
Extended Passive
Termination Resistor (100X) Terminal Equipment Network Termination
FIGURE Interface Network Configurations basic access rate interface line rate consisting D-channels (144 plus channel capacity which used framing maintenance house keeping
11270
FIGURE TP3420 Single Chip Interface Transceiver framing bits used carry slow speed (800 each) maintenance channels over 20-frame structure ``Q'' (from used request test loopbacks ``SC1'' ``SC2'' bits (from used acknowledge loopback requests well provide performance information from network Multiple interface passive protocol gain access common D-channel orderly controlled fashion using statistical multiplexing This procedure ensures that even when more terminals gain access D-channel simultaneously terminal will successful transmitting bits D-channel while other terminal(s) back There classes D-channel Access Signaling packets Class messages other packets packets) Class messages Class messages have higher priority than Class messages priority mechanism handled layer network switch interrogates signaling information acts routes packet data information Packet Handler which reside within ISDN outside ISDN Telenet Tymenet) Interface Transceiver interface transceiver needs work over number network configurations indicated Figure point-to-point network extend result signal attenuation National Semiconductor Corp's (NSC) Interface Device transceiver (block diagram Figure incorporates adaptive equalizer jitter clock recovery circuits provide good performance over extended range conditions passive signal attenuation severe pulse shape NT's receiver very distorted because pulses arriving from multiple (located different points bus) scattered over time window Sampling incoming data fixed time recommended achieve good performance under these conditions Mixed analog digital signal processing techniques used achieve high degree performance device jointly developed with SGS-Thomson Microelectronics available from both companies INTERFACE CHARACTERISTICS interface two-wire interface that consists local telephone line (also known Digital Subscriber Loop DSL) customer's home office North America ANSI committee adopted interface standard (T1-601-1988) specifying 2B1Q encoding 10b7 error rate pulse power level (over spectrum) nominal peak pulse voltage Since original specification 1988 ANSI committee added maintenance mode requirements equipment (detailed T1-601-1991 revision) 1983 Bellcore performed survey existing subscriber loops identified worst-case loops having different combinations wire gauges lengths bridge taps impedance characteristics expected that interface transceivers which work with these lines will work over percent subscribers lines North America Figure shows those loop configurations Loop longest range kft) hence most attenuation Loop multiple bridge taps causing multiple reflections outgoing pulses well distortions incoming pulses from
Other countries developing their worst-case test loops ensure acceptable performance within their environments Unfortunately current recommendations from CCITT interface still allows either 2B1Q 4B3T line codes thus some incompatibilities could exist across international borders Since percent world's digital lines North America (which settled 2B1Q standard) high volume production should make 2B1Q most cost-effective encoding scheme operating companies world-wide number vendors have interface transceivers using 2B1Q line code Central Office Customer Premises
Echo Cancellation Full duplex transmission over wires achieved using echo cancellation techniques (see Figure transformer Hybrid circuit performs 4-to-2 wire bridge with proper matching impedances transmitted signal coupled line received signal coupled receiver device However imperfect impedance matching characteristic impedance every substantial amount near transmitted signal reflected back into receiver same device reflected signal known Near Echo Some additional reflections occur points impedance discontinuity wire joints well point These Echoes suffer severe signal attenuation thus dominant source signal imperfection adaptive Hybrid circuit provide better matching impedances frequency band where much 2B1Q energy lies digital Echo canceller (composed finite response filter) used generate complete replica Echo coming back into receiver replica echo subtracted from total received signal thus extracting signal equalizer processes signal remove intersymbol interference allow correct detection transmitted data Timing also recovered from incoming waveform perform optimum echo cancellation equalization convergence adaptive loops echo-cancellation equalization automatic gain control well timing recovery impose many challenges transceiver designers
11270-6
American Wire Gauge
FIGURE ANSI Interface Loops Testing Received Signal Performance
11270
Local Transmitter Echo Internally generated replica Echo signal Total received signal
Echo Canceller Equalizer 4w-to-2w Hybrid
FIGURE 2-Wire Operation Using Echo Cancellation
11270
FIGURE TP3410 Single Chip Interface Transceiver Interface Transceiver National Semiconductor's Interface Device example single chip implementation interface standard (Block diagram Figure incorporates very high performance signal processing (equalization echo cancellation clock recovery) using both analog digital techniques achieve good performance over demanding conditions subscriber loop plant TP3410 incorporates echo-canceller circuits analog adaptive hybrid providing echo cancellation other fully digital echo-canceller rejecting remaining echo from received signal device jointly developed with SGS-Thomson Microelectronics available from both companies chip implements multiple chip-to-chip interfaces supporting programmable time slot access well interfacing European format ISDN SOFTWARE Layer Device Drivers Layer firmware consists drivers transceivers They control activation physical layer guide data routing process communicate maintenance channel information NSC's transceivers have high degree automation require little interaction with drivers Layer Protocols ISDN ISDN layer Data Link Control Layer CCITT standard (and TR268 Bellcore standard) specifies HDLC framing Link Access Procedure D-channel commonly known LAPD LAPD provides insequence error-free transmission packets LAPD handle multiple logical links ISDN there least three logical links running D-channel signaling functions (SAPI SAPI Service Access Point Identifier Terminal Endpoint Identifier maintenance functions (SAPI 127) D-channel packet data (SAPI ``a'' ``b'' arbitrary valid values range denote particular terminating entity which physical unit (signaling phone) physical port case D-channel data) channel data termination Layer requires implementation Link Access Procedures CCITT recommendation more commonly referred LAPB Like LAPD LAPB also provides in-sequence errorfree frames higher layers LAPB only handle logical link Layer Other terminal adaptation protocols discussed later section Layer Protocol Functions ISDN D-channel signaling termination Layer requires implementation Protocol Control procedures CCITT recommendation These procedures include setting tearing down local access connections between terminal Central Office These connections voice data services requested D-channels present Central Office Switches 5ESS DMS100) fully implement CCITT layer signaling standard 932) Therefore present ISDN equipment needs firmware which tailored communicate with particular switch time down-loadable based software changeable EPROMs methods being used allow portability different switch connections data calls packets must processed Layer Packet Layer Protocol These procedures include setting tearing down virtual circuits between end-toend terminals Selection Data Protocols hurdles facing widespread deployment ISDN confusion over terminal adapter techniques While standard been adopted connection terminals packet switches ISDN situation majority terminals which will require circuitswitched access less certain Currently there exist proprietary schemes mode (and mode Northern Telecom's T-link which already deployed network
national international level there other standards specification (driven primarily companies based adapting LAPD protocol work B-channel thereby utilizing advantages accepted packet oriented rate adaptation protocol Rate adaptation from slow speed achieved simply stuffing HDLC Flags between packets containing data also provides mechanisms flow control supports error free multiple logical channels more applications running over single B-channel specification (which evolved from ECMA-102 European standard) based 80-bit frame which incoming data repeated 1200 data repeated times) make 80-bit frame Some bits frame reserved carrying modem control signals frame synchronizing pattern end-to-end flow control advantage that protocol implemented silicon disadvantage there provision error checking re-transmission ensure error free end-to-end transmission ISDN Service Procedures (Europe Japan) Circuit Switched DMI-1 DMI-2 T-Link (Canada (Europe Japan) Packet Switched Circuit Mode Packet Mode Ports ISDN Channels
ISDN CUSTOMER PREMISE EQUIPMENT ISDN simple terms unit just unintelligent which converts from wire ``U'' interface wire ``S'' interface However multiple options implementing this function possible Europe Europe this equipment owned Telephone operating company guaranty service including equipment customer attaches Terminal Equipment workstation multiplexors this unit ``S'' interface point operating company will supply power unit signaling pair limitation amount power supplied unit kept simple possible supports minimal loop maintenance features (such B-channel loopbacks some error performance monitoring functions) North America owned RBOCs customer buys equipment open market installs maintains this unit locally powered addition could provide power terminal (such phone) units rack mounted common large battery associated with rack would supply power ``emergency'' phones case local power failure terminal sites Since owned customer much like telephone equipment operating companies (RBOCs) have requirement that should support some maintenance modes which remotely exercised field personnel case reported fault condition test equipment tapped line (either central office somewhere along path customer premises) will send trigger pulses (similar dial pulse stream used phone system today) control maintenance modes unit (see Figure When receives trigger pulses should enter ``Quiet mode'' which should ignore signals that present line tester performing Return Loss measurement Impedance tests With detection trigger pulses should enter ``Insertion Loss Test mode'' during which transmits known signal pattern which tester side uses determine acceptability signal loss down cable Detecting pulses causes enter ``Normal'' mode which responds normal activation sequence signals originating from central office line card
FIGURE Table Data Protocols
11270
FIGURE Maintenance Modes Unit
Implementation example shown Figure consists interface transceiver interface transceiver cost micro-controller Some discrete circuitry required detect sealing current trigger pulses Optoisolator converts high voltage pulses level which filtered processed micro-controller firmware keeps count trigger pulses performs necessary actions
11270
FIGURE Interface Repeater Application Pairgain Application Increasing demand additional phone line services forced RBOCs produce Pairgain standards They make 2B1Q transmission technique defined ANSI T1-601) transport digitally multiplexed voice channels (carried over channels) from Central Office Terminal (COT) Remote Terminal (RT)
11270
FIGURE Unit firmware also monitors activation states both loops responds test loopback performance monitoring messages from either Central office equipment user terminal equipment Europe maintenance requirements minimal this case microcontroller very frequency conserve power Interface Repeater interface repeater necessary extend range subscriber beyond range limit each section repeater implemented connecting UIDs back-to-back shown Figure simple 8-bit microcontroller performs loop maintenance functions well normal activation deactivation sequences
11270
FIGURE Pairgain Application Using 2B1Q Interface voice CODECS connected remote (one each B-channel) output analog voice Full SLIC functions give features full RJ11c port subscriber allowing access analog lines which originated single wire line from central office Figure Methods carrying Call progress information such Ringing Busy generally proprietary make either D-channel maintenance channel
TERMINAL EQUIPMENT IMPLEMENTATION general term ISDN Terminal Equipment (TE) implies ISDN phones ISDN phones with data capability various types Terminal Adapters (TA) these solutions convenient have common flexible cost effective high performance solution ISDN ``S'' interface connectivity three protocol layers ISDN
Figure shows typical implementation heart ISDN terminal equipment TP3420 ``S'' Interface Device (SID) implements layer functions specified CCITT activation ``D'' channel access algorithms handled automatically within device minimize interaction with controlling microprocessor Complementing transceiver HPC16400E Integrated Communications Controller HPC16400E consists 16-bit core (with 8-bit 16-bit external data bus) number internal peripherals internal HDLC controllers four associated controllers handle data transfer with minimal interrupt overhead addition there full UART four timers serial decoder implement multiple chip chip interfaces HPC16400E with software handles channel signaling well different rate adaption protocols such modes channels
RJ11c Port Today's voice data communication equipment analog phone lines accessed through RJ11c jack wall decline cost this equipment well large
investment feature phones machines data MODEMS forces co-existence ISDN services well todays services Hence number today's ISDN terminal adapters provide RJ11c port allow access this equipment provide this port necessary implement simplified analog line card functions CODEC device (such TP3076 COMBO) converts analog signals into digital signals which will transported over ISDN Further Subscriber Line Interface Circuit (SLIC) provides 4-to-2 wire conversion Ringing signal perhaps sufficient power source supply current simple analog phone Ringing signal needs high voltage activate circuits today's equipment such machines MODEMs DTMF transceiver necessary detect DTMF signaling tones originating from these equipments then call progress tones trunk busy) need sent back equipment provide status call Additional software required convert DTMF signals ISDN D-channel messages initiate call similarly returning call progress messages converted call progress tones Attaching PSTN Equipment ISDN Figure show couple scenarios connecting today's equipment ISDN lines first case machine MODEM phone connected RJ11c port ``S'' interface terminal adapter this case terminal adapter could stand-alone providing multiple RS232c ports with RJ11c port
11270
FIGURE Core ISDN Terminal Equipment
11270
FIGURE ISDN Terminal Adapter Connecting Analog Equipment Function Terminal Equipment some Terminal Equipment contain function hence will directly connected ``U'' interface This saves cost having separate unit have provide interface connection This type equipment drawbacks though that only used Europe Japan where needs separate physcial unit owned local telephone company Secondly eliminated thus there local sharing Basic Access channels This type with direct interface output likely most popular ISDN Home market where ISDN terminal with RJ11c jack connect analog phone possible scenario (see Figure This unit (card) would also required support maintenance modes functions described regular unit ISDN Multiplexors Concentrators small businesses ISDN Basic Rate Multiplexors will allow multiple terminals share Basic Access lines This allows existing terminals phones onto ISDN network through Multiplexors provide full Rate adaption from Asynchronous Synchronous RS232c data streams ISDN synchronous rates This kind product would contain multiple SIDs UIDs connect ISDN network RS232c RJ11c ports inter-connect present equipment INTER-OPERABILITY CONFORMANCE TESTING ISDN equipment adapting national international standards signaling rate adaption essential ensure compatibility between equipment from different vendors ISDN users' groups such ISDN users' Forum users' group working towards implementation agreements allow inter-operability between different vendors equipment designed same standard Switch independent Conformance tests ISDN standards have been developed ISDN Implementer groups Bellcore have established conformance testing labs certify customer premise equipment with individual central office switches
11270
FIGURE Terminal Adapter Individual Subscriber
ISDN Basic Access Components Design ISDN Peripherals
CONCLUSION Regional Bell operating companies have started provide ISDN lines services home subscriber limited basis Competitive tariffing integrated services (including slow-scan video) needed spur widespread acceptance ISDN ISDN equipment becomes accepted expected high volume will lower cost highly integrated silicon solutions which will turn drive overall equipment cost down compete with current phone equipment high speed MODEMs cost equipment whether standalone embodied within terminal equipment essential bring ISDN services home REFERENCES CCITT Recommendations Interface 440(Q 920) 441(Q 921) LAPD 450(Q 930) 451(Q 931) Signaling protcols 1988 Blue books CCITT Recommendations Data Communication Protocols 1988 Blue books
ANSI standards T1-601-1991 Interface) T1-6051991 Interface) Bell Core standards TR268 LAPD procedures TR-TSY-397 TA-TSY-398 Paripatyadar ``ISDN Basic Access Model (Standards Implementations)'' Conference Record IEEE Systems Design Networks Conference 1990 Kimyacioglu ``User Network Interfaces ISDN BISDN'' conference record IEEE Systems Design Networks Conference 1989 Weissburger ``Terminal Adapters'' Data communication Applications Note AN-492 ``An intuitive ISDN tutorial'' Applications Note AN-520 ``Building ISDN Terminal Adapter'' Applications Note AN-664 ``ISDN System Design Guide'' Batruni ``Mixed Digital Analog signal Processing Single Chip 2B1Q Interface Transceiver'' IEEE 1990
LIFE SUPPORT POLICY NATIONAL'S PRODUCTS AUTHORIZED CRITICAL COMPONENTS LIFE SUPPORT DEVICES SYSTEMS WITHOUT EXPRESS WRITTEN APPROVAL PRESIDENT NATIONAL SEMICONDUCTOR CORPORATION used herein Life support devices systems devices systems which intended surgical implant into body support sustain life whose failure perform when properly used accordance with instructions provided labeling reasonably expected result significant injury user critical component component life support device system whose failure perform reasonably expected cause failure life support device system affect safety effectiveness
AN-796
National Semiconductor Corporation 2900 Semiconductor Drive 58090 Santa Clara 95052-8090 1(800) 272-9959 (910) 339-9240
National Semiconductor GmbH Livry-Gargan-Str D-82256 F4urstenfeldbruck Germany (81-41) 35-0 Telex 527649 (81-41) 35-1
National Semiconductor Japan Sumitomo Chemical Engineering Center Bldg 1-7-1 Nakase Mihama-Ku Chiba-City Ciba Prefecture (043) 299-2300 (043) 299-2500
National Semiconductor Hong Kong 13th Floor Straight Block Ocean Centre Canton Tsimshatsui Kowloon Hong Kong (852) 2737-1600 (852) 2736-9960
National Semiconductores Brazil Ltda Deputado Lacorda Franco 120-3A Paulo-SP Brazil 05418-000 (55-11) 212-5066 Telex 391-1131931 NSBR (55-11) 212-1181
National Semiconductor (Australia) Building Business Park Drive Monash Business Park Nottinghill Melbourne Victoria 3168 Australia 558-9999 558-9998
National does assume responsibility circuitry described circuit patent licenses implied National reserves right time without notice change said circuitry specifications

ISDN Basic Access Components Design ISDN Peripherals ABSTRACT Int

Top Searches for this datasheet

Other recent searches