Rev. 0.01 corDECT Table Contents Introduction. Importan

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corDECT Training Manual
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corDECT
Table Contents
Introduction. Important Attributes system Capacity. Cell Planning Frequency Planning Reuse. Inter cell Hand over Migration inter- cell capacity Redundancy Overview Wireless Local Loop Cellular Technologies AMPS. Pan-European Cellular System (GSM) Digital AMPS CDMA Cellular System Digital Enhanced Cordless Telecommunications (DECT) DECT Standards Features DECT Does DECT Provide High Traffic Capacity? DECT Wireless Local Loop. Remote Line Switching Unit DECT RLU/RSU DECT Network Protocols. What Protocol DECT Needs Network Protocols DECT Economical Solution DECT Initial Installation Growth Scenario. corDECT- DECT based Wireless Local Loop Voice Coding Standards Frequency band. Services Access Technology. Dynamic Channel Selection Major Subsystems corDECT PSTN Interface Typical Configuration corDECT System. corDECT Deployment Scenarios. Possible Scenarios corDECT Deployment Exchange Street Level. Cluster Exchange. Remote Location with Cluster. Multiple DIUs Fibre Backbone Clusters with Digital Microwave Links Clusters with HDSL Fibre links Validation Issues ETSI Certification. Technology Alternatives-Often Asked Questions Operators Service Providers Regulatory Issues. Regulators view point. Conclusions.
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corDECT Appendix DECT Physical Layer Specifications. Appendix System Capabilities. 12.1 Traffic Handling 12.2 Voice Data Appendix General Features Appendix Supplementary Services Appendix Other Services. Glossary Abbreviations.
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Introduction
years hardly anyone would have thought local loop anything more than physical wires connecting telephone subscribers' phone public branch exchange (PBX) telephone company's central office switch. That beginning change wireless local loops (WLL) find their into densely populated areas well secluded remote areas. Most telecommunication majors world have identified significant emerging market. does require great extent market research find reasons. There billion people world only small fraction them -say, have telephones most these larger urban homes businesses USA, Canada, Western Europe, Japan Australia. market systems developed world already have well developed copper fiber optic cable infrastructure likely that third world countries. This because countries with underdeveloped telecommunication infrastructure have realized that country's economic development success today's global market significantly dependent quality telecommunications. result these countries would want leap frog into state state technologies like Wireless Local Loop cost effectively efficiently develop their telecommunication infrastructure least possible time.
Telephone Network Today
PSTN
Trunks
PILLAR
Local Loop
Figure Telephone Network Today
Important Attributes system
technology meant urban areas must, first foremost, capable catering upwards million subscribes densely populated metropolitan area. This achieved, given operating bandwidth, howsoever generous, only spatial frequency reuse done mobile cellular systems. capacity cellular system given bandwidth determined only some extent modulation format other related parameters primarily reuse factor, equivalently, cell size. makes cells smaller, transmit power levels reduced, same frequency reused more often, leading higher capacity. lower transmit power level incidentally also serves extend battery life hand sets.
Capacity
While micro-cellular architecture only route high capacity, there problems associated with transmit-power levels, cell shape area reached transmitted signal) very unpredictable depends local propagation profile, obstructions, etc. Irregular cell shapes sizes render attempt cell planning frequency planning futile.
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Cell Planning
Cell planning avoided following manner. Associated with each cell potential coverage area (PCA) under free-space propagation conditions, actual coverage area (ACA) determined local propagation conditions(Figure need even contiguous, will contained PCA. irregularly shaped cell that unpredictable. solution covering entire area overlap PCAs generously that probability location falling least very small. Most locations will fall more than ACA. Figure Potential coverage area(PCA) under free-space propagation conditions actual coverage
area (ACA) cell
Frequency Planning Reuse
Frequency reuse planned when cell boundaries sizes least approximately predictable. mobile cellular systems, frequencies allocated planned manner, subscriber crossing over from cell another another hands over call from frequency goes another. hand over administered Base station. cell site associated with each cell. micro-cellular system, frequency planning ruled out, hand-over must decided handset subscriber based measured interference levels that point space time. achieve very high probability successful hand over, each handset must have potential choice available frequencies earmarked entire system without apportioning them among cells. FDMA system this means that handset must capable switching over during call hundreds FDMA channels. FDMA system, handset must capable transmitting time-slot available frequencies. Thus, frequency change from slot slot. This type TDMA referred Multi-Carrier TDMA (MC-TDMA) cross between conventional FDMA TDMA.
Inter cell Hand over
micro-cellular system with handset-arbitrated hand over, interference profile changes with time even fixed location because other hand vicinity taking independent decisions. Thus, even fixed handset switch over during call from channel anther (intra-cell hand over),and/or from base station another regions overlapping ACAs(inter-cell hand over).
Migration inter- cell capacity
Another important attribute system ability migrate capacity areas where call density high certain times. micro-cellular system with overlapping ACAs achieves this goal since handsets typically access more than base station from large fraction covered area. During intervals when call density high, handset probably access second base station even best from point view link quality fully busy serving other handset.
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Redundancy
final advantage accruing from having large fraction area falling multiple ACAs that even base-station were malfunction, handsets wallsets could continue operate other base-stations whose ACAs overlap with malfunctioning base-station.
corDECT Local Loop
PSTN
Trunks
Wallset
Telephone
corDECT Local Loop Typically Pairs wires telephone subscribers
Figure typical Wireless Local Loop Thus, system must micro-cellular achieve very high capacity transmit power levels. Have overlapping cells overcome cell-size unpredictability, reduce blocking probability capacity migration, provide measure fault tolerance. Have self-organizing handset-arbitrated hand-over obviate need frequency planning Interface easily with major switch-types telecommunication networks quality range services provided over wired loop should maintained atleast same level should also support services planned future.
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desirable ireless
Toll Quality voice kbps kbps ADPCM
expandable ISDN
Traffic handling capacity (0.05 0.15
subscriber)
Large telephone density illion subscribers city) ited frequency spectrum
Cost Power Figure Desirable Attributes Local Loop
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Overview Wireless Local Loop Cellular Technologies
concept new. some sense, mobile cellular systems, which have been around more than decade provide from moving vehicle. case mobile subscriber, there other option WLL. mobile cellular phone could also used fixed portable phone. Thus existing mobile cellular system deployed provide home, office, vehicles. However, systems designed mobile purposes have limitations when used homes office.
AMPS
This good example first-generation mobile cellular system. widely deployed North America other countries. AMPS operates band. analog system using radio link between handset base stations from where voice signal enters telephone network. voice quality wireless link toll-quality. implication this that AMPS system does guarantee every service normally possible from wired telephone, example,, data communication using modems, fax, etc. Digital services such ISDN also ruled out. Prior AMPS, mobile telephony provided using radio channels allocated permanently subscribers. Given limited bandwidth availability, number subscribers limited. AMPS among first employ cellular concept. this approach, coverage area divided cells certain number radio channels allocated each cell. subscriber moves cell another, call handed over from channel another automatically system. feature cellular approach that frequencies reused geographically dispersed cells. example AMPS around channels reuses channels every cells. radius AMPS cell vary from 2-15 depending subscriber density expected different geographical areas. power transmitted from handset Total Access Communications system (TACS) deployed Europe similar AMPS.
Pan-European Cellular System (GSM)
digital mobile cellular system been standardized second generation cellular system deployed over Europe, being adopted many other countries like India China. Like AMPS, also operates band, though some bandwidth 1800 band also been allocated. Unlike AMPS, system digital, voice signal digitized from handset itself. order conserve bandwidth, rate been kept around Kb/s. this rate, possible provide tollquality despite digitization leading same limitations mentioned above AMPS system. employs Time Division Multiple Access (TDMA) contrast AMPS which employs conventional Frequency Division Multiple Access(FDMA). also employs sophisticated techniques like power control from handset base station level needed depending upon handset base station separation particular time. This conserves battery charge improves frequency reuse efficiency. Cell sizes same order AMPS, though somewhat smaller cells also permitted.
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Digital AMPS
order digitize mobile phone system improved quality higher call-carrying capacity, digital overlay AMPS system been deployed. Here, channel carrying voice link analog AMPS, carries three-channel digital TDMA signal, handling three calls. system, like GSM, advantages digital cellular system, while co-existing with installed analog AMPS systems. Dual-use hand operate both areas with analog AMPS digital AMPS. Digital AMPS also does provide toll-quality voice links. system also referred North American Digital Cellular System IS-54.
CDMA Cellular System
new-generation digital mobile cellular system emerging that employs spread spectrum modulation code division multiple access(CDMA) that goes hand-in-hand with Similar other cellular systems, this system also does provide toll-quality. CDMA systems require very accurate power control proper operation. System performance very sensitive accuracy power control until widely deployed proven field call-carrying capacity CDMA systems will questioned. CDMA systems have important advantage that they need frequency planning. other systems, channels have allocated different cells depending expected subscriber density that cell. density changes, cells have divided, extra channels allocated proper planned allocation available bandwidth non-trivial task.
Digital Enhanced Cordless Telecommunications (DECT)
cellular systems described till have designed mobile application, therefore optimized They have been designed certain typical levels call traffic density Erlangs/sq. consistent with expected call traffic call hold-times from vehicles. Given that background noise mobile environment anyway present, lower voice quality level acceptable exchange bandwidth efficiency. Full-fledged data services expected from vehicles, though overlay data service called Cellular Digital Packet Data (CDPD) being implemented customer demand. None mobile cellular systems well-suited homes offices. call-carrying capacity these systems inadequate traffic levels generated offices. signal quality, being less than toll-quality, does permit capabilities normal wired phone. Further, upgrade ISDN services possible. Since cell sizes large design transmit power levels high (~1W). This problem powered vehicle limitation portable phone. Finally, except CDMA, mobile cellular systems cannot migrate capacity dynamically geographical areas that need more capacity given time, inherent limitation fixed channel assignment cells. DECT standard recently proposed European Telecommunication Standards Institute(ETSI) overcomes these problems mentioned above, ideally suited application. also used wireless PABXs, telepoint systems wireless LANs. third generation cellular system precursor Personal Communication Network (PCN). similar system called Personal Handy Phone (PHP) been adopted Japan.
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corDECT Prior DECT, much simpler system called CT2, with some similarities DECT proposed implemented. permits only outgoing calls from handset, thus suitable only payphone. However, digitized from handset onwards does provide toll quality with transmit power recent addition CT2, called CT+, integrates pager with handset. This allows phone number calling subscriber incoming call displayed hand set, permitting user call back. addition, CT2+ employ Fixed Channel Allocation(FCA) have very limited callcarrying capacity.
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DECT Standards
DECT MC-TDMA self-organizing micro-cellular standard that attributes listed previous section, more. Further, DECT-GSM interface being defined that same handset work from home, office. countries like India which have decided favor cellular telephony, DECT very attractive standard look into wireless local loop applications. number major international telecommunication companies have already announced DECT components products.
Features DECT
Listed below several important features DECT that make good choice wireless local loop. Frequency band 1880-1900 frequency band clashing with allocation mobile cellular communications. second frequency band also being considered enhancement. Mode Multiple Access Multi-Carrier Time Division Multiple Access modification conventional TDMA which easily implemented which gives greatly increased capacity. Voice Coding Kb/s ADPCM half bit-rate without disadvantages. Provides toll quality services handle voice-band data signals 9600 bits second. Number Frequency Bands bands, each 1.728 bandwidth with twelve time-slots carrier frequencies, total channels available dynamic selection. Number simultaneous calls: base station system Time Division Duplex (TDD), with twenty-four Kb/s voice slots frame. Along with signaling other overhead, total bit-rate 1.152 Mb/s. Half- Double-Slot Capability. possible allot Kb/s handset using double slot. number voice channels doubled future using only pair half-slots call Kb/s voice coding. Size Cell Transmit Power: "radius" cell expected about under typical urban conditions, though cell will rarely circular average power only 10mW (One tenth power home cordless telephone.) .This power level means that phone operate long hours without charging batteries. This very important since wireless phone will powered exchange, unlike conventional phone. Subscriber Density: DECT achieves very high, uniform, phone densities employing self-organizing handset-arbitrated dynamic channel selection scheme. Base stations installed uncoordinated fashion subscriber density increases. DECT been designed handle subscribers densities high 5000/sq.
Enhancements: DECT enhancements future are:
DECT ISDN DECT Data Wireless LANs upto 1.152 MBPS General Access Profile (GAP) Cordless Terminal Mobility
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Does DECT Provide High Traffic Capacity?
While small cells used DECT high capacity provides, have seen that small overlapping cells cause some problems. unpredictable offered traffic, unpredictable radio propagation environment unknown interference from adjacent systems present difficult scenario. Well-defined cells frequency planning therefore ruled out. DECT solves problem uncoordinated system installations co-existing common frequency resource systems. systems operate selforganizing choosing time frequency channel that time being best desired local connection avoiding splitting common frequency resource between different services user providing additional capacity gain: Allowing easily engineered economic installation closer closer cells Dynamic inter-cell intra-cell hand over which elegantly copes with changing conditions, without need central control. hand overs quick seamless (without interruption). Dynamic Channel Selection (DCS) hand over technique probably most important concept which allows small cells with power transmission thereby high traffic density. dynamic channel selection algorithm used DECT robust efficient physical channels between hand sets their closest base stations allocate decentralized hand sets. important advantage that different systems system operators different types services utilize same available channels without prior distribution channels specific services base stations. This contrast systems such AMPS which operate principle Fixed Channel Allocation (FCA). These systems therefore need planned worst-case situation, while DECT takes actual interference situation into account. consequence DECT dynamic channel selection procedure that there need plan detail many channels needed base station. seamless hand over TDMA combination with decentralized dynamic channel selection, where link maintained slot handset, while link parallel another time slot (and possibly another frequency). When link established, base station (which now) requests system switch seamlessly from channel. hand over controlled handset. While handset communities original link, scans other channels records free channels identities base stations whose signals stronger that current one. Hand over made when another base station stronger than current found. increase probability finding stronger base station, base stations employ antenna diversity change radiation pattern. hand over performed well before link quality deteriorates. DECT does depend channel quickly one. inter-cell intra-cell hand over increased capacity cuts call curtailment drastically. high capacity DECT primarily opposed used first second generation cellular systems. main advantages follows: does need shadowing margins, adjusts instant situation allowing sometimes shorter sometimes longer reuse distances. dynamic reuse distance also because portable close base station will have shorter reuse distances. gives better trunking efficiency since channels used base station handset. When used conjunction with microcells, average strength wanted signal increases cells made smaller, leading higher carrier interference ratio.
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DECT Wireless Local Loop
objective DECT technology provide telephones business homes urban areas within relatively short time with minimum expenditure. These telephones added existing network, providing services which least good those provided wired local loop today also capable adding services like Narrow band ISDN which being added wired loop. same time this technology should require network planning numbering scheme. Ideally technology should added existing telecommunication network with existing switches. Changes hardware software switches would huge task would almost rule acceptance technology. Even administrative software switches should changed minimum extent, all.
Remote Line Switching Unit
most straight-forward connect DECT existing network configure Remote Line Unit (RLU) Remote Switching Unit (RSU) existing switches. These digital switches, with very little blocking, have significantly improved telecommunication services urban India. Further, these switches support RLUs/RSUs connected them using multiple channel 2.048 Mb/s CEPT (G-703) links local loops terminated RLU/RSU which subscriber line interface. switching administration services provided main switch. acts concentrator connect subscriber switch using available ports Mb/s links whenever subscriber called makes call. RSU, addition, switches calls between subscribers connected Typically, 800-1000 subscribers supported four 2.048 Mb/s links channels).
2.048 Mbps
Telephone
10/B
Telephone
Figure used connect subscribers switch 2.048 Mb/s links Besides voice channels, each 2.048 Mb/s links carry Kb/s signaling channel between switch RLU. signaling protocol used between switch RLU/RSU standard varies different types exchanges. Modern digital switches designed support large number RLUs/RSUs simultaneously. number subscribers grouped into cluster, geographical area served more base stations which subscriber mobility, that handset hand over call bases cluster which maintaining integrity call. cell area pre-defined vary depending propagation condition radio signals. DECT Interface Unit (DIU) provides control concentration functions subscribers cluster.
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2.048 Mbps
10/B
Cluster
Figure DECT used connect many hand sets base stns then exchange. Each base serves cell, each serves cluster. link from each base station provides full-duplex ADPCM Kb/s) channels along with required signaling. link provided standard telephone wires Narrow band ISDN three pairs achieve required rate. Alternatively, 2.048 Mb/s links with drop-and insert facility used, serving many four base stations. base stations small units which mounted poles junction boxes. Each base provide 30-80 hand set, depending many office phones many residential. Since channels provided each base station, number hand sets supported depends concentration that acceptable (the RLUs deployed today network employ concentration factor 4-8). base-handset link MC-TDMA radio link described Section base broadcasts signals subscribers located cell (again, defined terms propagation conditions). DECT handset listens base station broadcasts vicinity locks itself base from which currently receiving strongest signal. Therefore, handset portable does strictly belong cell move within cluster, connecting different base stations different times.
DECT RLU/RSU
DECT will designed appear RLU/RSU switches. interface though standard 2.048 Mb/s links described above software switch side altered manner. DECT-WLL will consist three subsystems: DECT Interface Unit (DIU). DECT Base station fixed part (BS). DECT handset portable part HS). appears RLU/RSU further helps reducing cost. typical scenario, have four G703 links exchange support base stations 800-1000 subscribers. Assuming 1000 subscribers four G703 links, notice following: Line cards subscribers required exchange. Instead line cards 1000 subscribers, only four 30-channel G703 link interfaces need provided exchange. Even DIU, line interface required each subscriber, whereas conventional RLU/RSU, line interface needed each subscriber. transcoding ADPCM vice-versa carried needs performed only channels. links from base station carry ADPCM voice instead voice, reducing link capacity required. base handset communication course, wireless ADPCM format defined DECT. Each handset codec PCM-ADPCM transcoder required DECT.
DECT Network Protocols
DECT all-digital network. Besides call signaling, requires extensive data communication control. This includes coping with allocation radio channels. Since radio links have operation. With this, DECT akin packet-switched computer network. design DECT draws heavily years technology development experience computer networking. signaling control DECT uses packet
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corDECT communication. This necessitates multiple protocols layered according standard. fall this design that DECT well-suited wireless also.
What Protocol
meaningful communication take place between more entities such persons computers, certain conventions must agreed upon followed parties. These include communication medium interpretation each symbol message, reaction party each action other. Such conventions protocol. Communication take place only interacting parties exactly same protocol.
DECT Needs Network Protocols
different components DECT need communicate various types information amongst themselves, work co-operatively various tasks. These include: Radio Channel allocation :Each handset base communicate channels. channel used change from time time motion handset etc. fair efficient allocation time slots, medium access control (MAC) protocol used. Each above tasks requires protocol. addition, radio susceptible noise which cause errors information being transmitted. some cases, this serious problem, e.g., some "static" audio signal usually tolerated listener. other cases, however, noise problematic, e.g., dialled number changing from 235-1365 435-1365 single being corrupted during transmission clearly unacceptable. Hence, protocols some above tasks must include error detection correction measures.
DECT Economical Solution
addition wired local loop, each subscriber have dedicated part circuit line interface card switch RLU/RSU. local loop interface circuit required per-subscriber basis which form significant part cost telephone line. local loop 30-40% overall per-line cost, line cards around cost switch. DECT-WLL proposes replace wired line subscriber premises wireless access. Cost effectiveness well maintainability primary considerations. Making DECT-WLL appears RLU/RSU further helps reducing cost. typical scenario, have four G703 links exchange support base stations 800-1000 subscribers.
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corDECT Assuming 1000 subscribers four G703 links, notice following: Line cards subscribers required exchange. Instead line cards 1000 subscribers, only four 30-channel G703 link interfaces need provided exchange. Even DIU, line interface required each subscriber, whereas conventional RLU/RSU, line interface needed each subscriber. transcoding ADPCM vice-versa carried needs performed only channels. links from base station carry ADPCM voice instead voice, reducing link capacity required. base handset communication course, wireless ADPCM format defined DECT. Each handset codec PCM-ADPCM transcoder required DECT. approach only cost-effective also reduces processing base station transcoding performed there. base station becomes smaller operated power supplied from DIU. maintenance also becomes simpler. located exchange, which would have power plant maintenance personnel. possible place away from exchange nearer locality being served providing 2048 Mb/s links with exchange twisted pair.
DECT Initial Installation Growth Scenario
described earlier, DECT caters very high traffic density levels. Simulations performed ETSI have shown that traffic density large 10,000 E/km2/floor achieved multi-storey office complexes increasing number base stations. residential environment traffic density E/km2 easily achieved mounting base stations poles placing them residential building important note that since frequency planning required, base station installation unco-ordinated. take typical urban residential area examine DECT installed. area base station needs located every 200-300 apart spacing between base stations need uniform exact location base station unimportant handset area will find more than station distance less than 200-225 meters. Initially, there could base station every subscribers base stations. Thus subscribers could served start with. requirement telephone service area grows, subscribers permitted base station corresponding Erlang subscriber.
400m 300m
Figure DECT Initial Installation Growth Scenario
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corDECT Thus number subscribers increased 1000 within without additional base stations. areas with number business premises higher residential density additional base stations installed cater higher traffic levels. Additional base stations installed when needed place, since base- station installation need co-ordinated. smallest will have four 2.048 CEPT links exchange. These provide channels which offers about Erlang traffic (with blocking) subscriber served configuration. configuration capacity higher depending percentage calls between hand sets within area served DIU. Since each base station provide average Erlang traffic subscribers, base stations connected configuration, higher number base station configuration.
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corDECT- DECT based Wireless Local Loop
Copper wires have provided access telephone network past hundred years. technology recently emerged which promises change this. Wireless access mobile users being looked component serve subscribers densely populated areas. Along with optical fibre, threatens break monopoly copper.
Voice Coding
local loop, toll quality voice required. This implies either Kbps Kbps ADPCM voice coding. traffic originating from telephone should assumed less than 0.05 Erlang could high 0.15 Erlang some lines. Yet, call blocking should more than local should cater large subscriber density. About 1000 subscribers/sq. would minimum, some areas with large offices, many 10,000 subscribers/sq. have served. expected that wireless handset will have battery which could provide sufficient back-up power, implying that preferable have transmission power. copper-based local loop costs around from 12000-18000 therefore, Wireless Local Loop solution should cost more than, say, 12000 line.
Standards
DECT standard proposed European Telecommunication Standards Institute(ETSI) thirdgeneration cellular system meant providing wireless access networks various types, from PSTN LANs. deals only with task defining interface user. implementation.
Frequency band
band allotted DECT 1800-1900 MHz. DECT-based systems operate common band with requirement regulation. DECT standard employs Time Division Multiple Access(TDMA). There frequencies operation band, with spacing 1.728 MHz. burst-rate 1.152 Mbps, accommodating slots. communication Time division multiplexing(TDD). power transmitted handset base station during burst, about average power.
Services
DECT employs Kbps ADPCM. This ensures toll quality permits data (Fax/modem) services available from conventional wired connection. also possible occupy double-slot transmit Kbps using PCM. This permits upgradation narrow-band ISDN(actually, double-slot permits rate somewhat higher than Kbps allow channel (N-ISDN).
Access Technology
very important feature that sets DECT apart from conventional TDMA systems that slots TDMA frame need transmitted same frequency. Each slots could different frequency, though pair slots used each link must same frequency. This variation TDMA called Multi-Carrier TDMA(MC-TDMA) high capacity achieved DECT. slot-pairs frequencies give rise channels, they independent another.
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Dynamic Channel Selection
DECT standard employs completely decentralized channel allocation procedure called Dynamic Channel Selection (DCS) Adaptive Channel Allocation (ACA). this approach, available channels distributed priory among cells. handset call channels., deciding will given time measuring signal strength that channel geographical location. Thus, high capacity systems like DECT. more than makes inefficient bandwidth utilization other constraints effects channel allocation based actual traffic situation actual interference situation. gives significant capacity gain when compared other channel allocation schemes.
Advantage Overcomes propagation environment Makes frequency planning redundant Cells overlapping Channels re-used very often
Figure Advantages Dynamic Channel Selection
Major Subsystems corDECT
corDECT system four major subsystems: DECT Interface Unit(DIU) Performs system control interface PSTN Compact Base station (CBS) Provides wireless access area with twelve channels Handset(HS) Portable telephone providing voice service user. Wall set(WS) Wireless fixed terminal that connected standard telephone. modem. Each corDECT unit comprises DIU, compact base stations, 1000 number hand sets wall sets, typically between CBS. wall used from base station with line-of-sight-link, while handset typically used 50-200 from base station depending obstructions between base station itself. Each base station connected using three copper twisted cable. ADPCM switch used interface between PSTN base stations. incoming outgoing calls routed CBS. Functions such call control, powering PCM/ADPCM transcoding, call set-up tear-down, handled DIU. System operation maintenance (O&M),and remote fault monitoring also performed form DIU.
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DECT Interface Unit
Fully redundant ADPCM switch ADPCM transcoding PSTN interface Call processing PSTN signalling interface Operation Maintenance Remote powering (120V management Protection circuitry accidental human contact pairs
Figure Features DECT Interface Unit
Base station small, unobtrusive pole-mounted wall-mounted unit. Each serves cell,
providing simultaneous speech channels. cell radius depends propagation environment antenna gain handset/wall Typically, ranges from 50-1000 meters. antennas diversity.
16.5 Weatherproof slots blind slot Internal external antenna Three copper pairs towards 2B+D basic rate each pair Power pairs from Works 1/2/3 pairs (4/8/12 simultaneous calls) Upto distance from
Figure Features Compact Base Station Handset small, lightweight portable unit operated from re-chargeable batteries allows user make calls from within coverage area base stations connected DIU. handset intelligence hand over seamlessly form base station another. same used with different DIUs(say home office) appropriate re-registration when moving from location another. Wall small wall-mounted unit with external antenna powered from mains. battery provides backup case power failure. external antenna provides gain extends range areas where density low. wall provides standard RJ-11 telephone socket that telephone, machine, modem even phone connected
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230V powered Battery backup (upto hours idle-time) Blind slot implementation Standard RJ-11 interface metering pulses External integral antenn
Figure Features Wallset
PSTN Interface
interfaced PSTN three different configurations. first configuration, connected PSTN using lines with R2-MF protocols acts independent exchange. second configuration, interface between PSTN called Incoming Trunk Outgoing Subscriber(ITOS) interface. Thirdly connected parent Exchange wire subscriber lines.
PSTN Interface
Handset
Concentrated Traffic
Radio Exchange/DIU Base Station
Wallset
Connect through trunk lines PSTNs independent exchange Connect Exchange with V5.2 with ITOS interface exchange (DID PBX)
Figure PSTN Interfacing possibilities
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Interface Scenario
Wallset Telephone
PSTN
Wallset Telephone
Wallset Telephone
Multiple DIUs connected single transit Exchange
Figure Interface Scenario-
Interface Scenario
Wallset Telephone
10/B
PSTN
C-DOT
Wallset Telephone
Wallset Telephone
Multiple DIUs connected multiple Exchanges
Figure Interface Scenario
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Typical Configuration corDECT System
typical corDECT system configuration shown figure below. cater 300, 1000 lines. corDECT system support 1000 subscribers. Each base station
Typical Configuration
DIU, Base stations, 1000 Subscribers interconnection PSTN Upto (2.048Mbps) lines connection Pairs copper Supports Erlang 0.5% blocking 0.07 E/line Subscribers 0.15 E/line Subscribers
Figure Typical Configuration corDECT System
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corDECT Deployment Scenarios
Being open standard, DECT defines only interface between base station customer terminal unit. interface from Base Station controller PSTN left operator choose, depending upon existing infrastructure, terrain, number subscribers, economic country specific regulatory conditions. standard backbone technologies-coaxial, fiber digital microwave. Thus, there great extent flexibility deployment irrespective subscriber base-dense urban suburban, business districts, rural isolated pockets like factories, resorts etc., which located away from populated areas PSTN switch. corDECT Wireless Local Loop system truly scaleable system which Ideal green field network also expand existing telecommunication network. corDECT with central system will able control vast service area with locating service personnel corDECT installations. corDECT systems deployed several economical ways. service providers operators recommended most appropriate solution maximise coverage revenue. corDECT solution works existing PSTN networks assumes there enough switching capacity bandwidth available going made available demand grows local loop.
Possible Scenarios corDECT Deployment
exchange street level. cluster exchange remote location with cluster. Multiple DIUs fibre backbone. clusters with digital microwave link. clusters with HDSL fibre links.
Exchange Street Level
This simple configuration which ideal places where existing wire plant unable cover vast areas subscribers, also difficult expand network urban rural areas. such situations existing wire plant released wireless local loop quick expansion undertaken with worrying about last mile problem.
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PSTN
Trunks
Wallset
Telephone
corDECT Local Loop
Figure Exchange Cluster street level This will enhance utilisation switching capacity network reduces breakdowns maintenance problems copper local loop. This very economical solution. (DECT interface unit) installed Exchange street level base stations will serve neighbourhood Power feed Base stations from hence Bases stations virtually maintenance free street level fail when there commercial power Each base station handle simultaneous calls serve 50-75 subscribers depending load grade service. itself provide service 1000 subscribers. network expands more DIUs base stations added need basis. This investment proportional revenue generation demand. base station installation purely demand basis frequency planning required. Subscriber premises equipment fixed Wallset Handset. Customer register handsets different locations service area. This same number used make receive calls from office home market place Airports. bill will generated subscriber these calls normal POTS tariff. Hence more number calls generated subscriber. This will enhance revenue operator leads better utilisation network.
Cluster Exchange
this scenario Local Loop totally wireless. This Ideal residential areas suburbs. Base station cluster tall structure tower which house multiple Base stations with directional Antennae. This will sectorise coverage adequate overlapping sectors ensure uniform coverage very large area.
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Wallset Telephone
Wallset Wallset Telephone Telephone
PSTN
Trunks
Wallset Telephone
Wallset Telephone
cluster exchange
Figure :DIU Cluster Collocated large Kms. Radius Kms) even more depending terrain application. base station clusters added demand grows frequency panning required. this type solution topographic planning required maximum coverage from cluster.
Remote Location with Cluster
this solution Exchange located away from service area Co-axial links provided upto city centres where DIUs Base stations located provide service concentration subscribers.
Wallset Telephone
Wallset Telephone Wallset Telephone
Wallset Telephone
Wallset Telephone
Wallset Telephone
Wallset Telephone
Wallset Telephone
Wallset Telephone
Wallset Telephone
Wallset
BASE STATION CLUSTER
Wallset Telephone
Telephone
Telephone
Wallset Telephone
PSTN
Trunks
Wallset Telephone
Wallset
Wallset Telephone
Multiple G.703 links
Wallset Telephone
Wallset Telephone
cluster away from exchange
Figure Cluster collocated remote from Exchange This Ideal solution installations where real-estate side cities prohibitively expensive install large capacity switches. However locations franchised small operators which investment minimised. This operator enter city centre with very small investment infrastructure. Multiple DIUs installed same location different locations provide maximum coverage.
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Multiple DIUs Fibre Backbone
Wireless Local Loop implemented this situation using large switching capacity provided central exchange. fibre optic ring built drop channels Every installation this solution totally eliminates copper. This very elegant solution. This requires additional multiplexers locations which drop insert channels back bone fibre network.
Wallset Telephone Wallset Telephone
DECT BASE STATION CLUSTER
Wallset Telephone Wallset Telephone
Wallset Telephone
City Center
Wallset Telephone Wallset
PSTN
Trunks
Telephone
Wallset Telephone
Wallset Telephone
Wallset Telephone Wallset Telephone
Wallset Telephone
Multiple DIUs with Fibre backbone urban rural areas
Wallset Telephone
Figure Multiple DIUs with Fibre Backbone
Clusters with Digital Microwave Links
back bone network metropolis built around Scaleable point multi-point Digital Microwave network. These microwave links terminated DIUs which wide spread. DECT applications GHz, GHz, used depending traffic distance requirement. lower frequencies distance coverage long line sight higher frequencies distance comes down reuse same frequency possible. These networks very reliable properly planned totally eliminates need copper fibre. this solution additional cost microwave system still attractive considering advantages has. This solution needs clearance from regulator additional frequency utilisation.
Wallset Telephone Wallset Telephone Wallset Telephone Wallset Telephone Wallset Telephone Wallset Telephone Wallset Telephone
Microwave Point multipoint Network
Wallset Telephone
Wallset Telephone Wallset Telephone
PSTN Network
Wallset Telephone Wallset Telephone
Wallset Telephone Wallset Telephone
Wallset Telephone Wallset Telephone
CLusters with Microwave links
Figure Clusters with Microwave links
Clusters with HDSL Fibre links
this solution street level base station served single pair copper wire which deliver Kbps bandwidth using High density subscriber link. This possible using HDSL technology which enhance capacity existing copper pair. Hence effectively copper pair serve subscribers handle simultaneous ADPCM calls. HDSL network normally star network. Using fibre base stations possible when cluster base stations have deployed multiple places. this situation multiple DIUs housed exchange building with help multiplexers Bandwidth
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corDECT resource managers) channels aggregated exchange selectively dropped Base station clusters with help small mux. This even though calls additional investment, still clean solution fully satisfies regulatory conditions where copper usage prohibited local loop.
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Validation Issues ETSI Certification
best part DECT standardisation work which been done ETSI guidelines testing certification. This makes DECT open standard also ensure compatibility among manufacturers DECT product. following available standards guidelines ETSI certification. These tests conducted approved test houses Europe equipment gets approval which sold installed public network Europe. countries certification revalidated local authorities. Many other technologies proprietary many able certify independent body test house. This important factor selecting technology deployment public network. Common Technical Regulations (CTRs) Technical Basis Regulations (TBRs) basic yardstick Type approvals independent Type approval houses Europe DECT products. Type approval agency good enough equipment anywhere Europe. following guidelines type approval which available now:
`Basic rate" Radio `Speech' Audio Public Access Profile This being replaced Generic access protocol. this going CIR22.
TBRs which going come effect near future are: DECT/GSM interworking during 1996 DECT/ISDN interworking during 1996 DECT/GSM dual mode planned 1996.
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Technology Alternatives-Often Asked Questions Operators Service Providers
operators service providers around world begin deploy digital wireless systems, they often confronted with difficult decision making necessary before choice technology made. Till recently most digital systems have used three TDMA standards. CDMA based standards emerging challenging TDMA very strongly. debate relative merits demerits been raging years till there real world large deployments CDMA based systems anywhere able draw firm conclusions. However much debate been relative merits demerits technologies/ standards from point view mobile wireless communications Wireless Local Loop Systems. There also been considerable debate TDMA CDMA Micro Macro systems wireless local loop, fact remains that today macrocellular system been deployed wireless local loop. will find companies trying sell systems, technologies solutions third world countries which were primarily design optimised mobile wireless communications wireless local loop. Hence essential marketing personnel aware often asked questions operators have ready answers. have attempted answer these questions form comparison table below. Network access technology criterion effective provision service customer. This access provided with distinct technologies. critical issue however while providing wireless local loop replacing wired local loop with wireless necessary that quality range services that provided over wired loop should maintained same level. Also technology should able support services that planned future- that should "future proof" There technology that optimal deployment scenarios choice will depend numerous parameters which listed table below with indication relative merits demerits technologies.
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Parameter Ease deployment
Microcellular More complex partly wired solution.
Macrocellular Less complex fully radio solution.
Remarks case microcellular systems also immediate fully radio solution. Available limited number subscribers line sight range base stations. Collocated with DIU.
Speed deployment
Expansion customer base
Flexibility deployment
Design optimization
More time deployment requirement cable Easy base stns. added demand dictates Traffic handling base stn. Flexible accommodate needs residential commercial areas. Optimized applications.
Quick installation limited customers More complex greater level coordination required. Less flexible single base station catering categories subscribers areas with varying traffic densities. Optimized mobile applications
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Parameter Suitability dense urban applications
Microcellular Design optimized dense urban applications
Macrocellular Design optimized comparatively thin route applications.
Speech compression techniques
kbps adpcm, kbps kbps ISDN possible
Uses speech specific compression algorithms kbps
Remarks spectrum availability mhz, spectrum channel khz, Erlang traffic ideal frequency reuse subscriber density/ Micro[250 cell radius]: 17000 without sectorisation 51000 with three sectors Macro[ cell radius]: without sectors with three sectors Please table end. Compression algorithms that take rate down kbps lower exploiting speech specific properties cannot handle modem signals which speech like.
Capability data Maintenance Redundancy
Easy Built cost basic design overlapping cell coverage base stns.
Much more complex Very complex safeguard systems required since transmitter serving many customers.
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Parameter Frequency planning
Microcellular required
Macrocellular Required
Remarks Micro: allows uncoordinated installation base stations current subscriber density expansion consonance with growth subscriber demand.
Power planning
required
Blocking/non blocking resultant grade service
Frequency reuse
fully loaded system add. Channels automatically blocked degradation grade service Reuse factor nearly
Power planning complex sophisticated power control algorithm required. Totally blocking cost degradation
Sensitivity cell borders
Intercell seamless hand
Support hierarchical cell structure
Supports
Typically reuse cells nearly achievable under certain circumstances. Maintains connection with earlier cell ,uses "soft hand off" uses more than demodulator hence pushes cost Does support
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Parameter phenomenon
Microcellular micro macro cells overlapping another
Macrocellular
Remarks phenomenon Coverage perfectly circular around omni antenna oval shaped. Hence different coverage ranges different directions.
Price drivershandset/wall Base station base station Controller costs.
cost
Small fraction total line cost.
Very high cost greater complexity handset/wall Significant portion total line cost
Subscriber Density
Assume:
Spectrum available Traffic Spectrum Channel Assuming reuse every cell Number subcribers/Sq.
Cell Radius 0.25 Non-Sectorised 17,000 4,240 1,060 3-Sectors 51,000 12,700 3,180
Erlang each way) Ideal reuse
Figure Microcellular Macrocellular systems.- comparison
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Regulatory Issues
time come Telecommunication regulators world take serious note what happening DECT world they DECT their countries through operators private users. today there divergent view DECT application Radio local loop many countries; however many regulators today agree fact that DECT very good standard which should utilized.
Regulators view point
DECT needs more frequency band (current band 1880-1900 Mhz) support ISDN services. appears that this request gaining momentum DECT world. Another 30-40 frequency band required. This concern many regulators. applications present band sufficient achieve very high telephone densities. "Hot spots" like Airports, Downtown areas, Railway Stations, etc., DECT frequency interfere with other operators equipment also with private installation that area. However this interference significant compared other technologies. carrier frequencies should reserved private DECT applications. This viewpoint regulators distinguish between office cordless applications view point regulators distinguish between office cordless application with WLL. This view ETSI. These should strategy interwork with public networks different operators synchronizing networks. This very important point many countries where network synchronization must connect public network. DECT provide same level service wired connections, such voice quality, Data speeds ISDN services along with guaranteed time. Interworking standards developed. Regulators accepting DECT/GSM services operators.
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Conclusions
Countries with underdeveloped telecommunication infrastructures have realized that modern, reliable efficient telecommunication facilities essential spurring economic growth, ensuring better living standards quality life their population. These countries need quickly increase their telephone penetration cost effective manner. Importantly, this must also cater pent-up demand, which unpredictable. critical path will local loop they choose with traditional wire-line systems. Hence, achieve quick affordable increased telephone penetration, wireless local loop answer. choice technology local loop would dictated many factors, would their advantage they adopt open standard which brings many manufacturers products into market. DECT standard that recommend achieve this objective. only does meet most important requirements wireless local loop anywhere world inherent features cater unpredictably growing demand without idle investment, case wireline systems. This critical characteristic makes ideal choice countries with underdeveloped telecommunication infrastructure. choice also makes sense because many countries outside North America have chosen standard cellular mobile services. originates from same stables DECT common handset planned systems through General Access profile. DECT scaleable capable being deployed innovatively cater dense urban suburban business residential districts, well less populated areas like rural areas isolated pockets demand like factories, resorts etc. most developed world idea paying getting plain telephone service (POTS) sound outrageous. however large numbers "telephone-starved" people these countries, would willing premium telephone connection demand. precisely this pent demand, that provides both operators consumers, opportunities innovative financing options. corDECT Wireless Local Loop solution been designed developed with these issues mind. summarise corDECT Wireless Local Loop following attributes that solution should have: Based open standards Reaches large number people shortest possible time affordable prices grow expand consonance with demand without idle investments Future proof.
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corDECT salient features corDECT Wireless Local Loop system are: state solution fully compliant with DECT standards. Quickly easily deployed. Easily expanded consonance with growth demand over whole pockets service area Viable cost effective. Most suited dense urban suburban business residential area Adaptable density rural other districts. design capable country adaptation. (Adaptation already done India China) technology partners have reference design production will easy. Chipsets designed used corDECT applications like cordless PBX, telepoint, wireless LAN, wireless ISDN terminal residential cordless.
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Appendix DECT Physical Layer Specifications
channel center frequencies Accuracy center frequencies TDMA time frame Transmission rate
TDMA slot length
1897.344 -1.728n, n=0,1-9 1.152 Mbps.
bits, with bits synchronisation bits signalling bits voice CRC.
Accuracy clock Modulation Frequencies deviation Transmit power Spurious emission
Sensitivity Interference performance
wallset/handset. base station. Gaussian frequency shift keying. (nominal) all- pattern. (nominal) all- zero pattern. nominal. Less than -8dBm adjacent channels. Less than dBm, channels away either side. Less than other channels. dBm, error rate BER) less than 10E-5. error rate BER) less than 10E-3. with co-channel interferer 83dBm, with adjacent channel uinterferer interferer channels away either side dBm, interferer other channel dBm, less than 10E-3.
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Appendix System Capabilities
12.1 Traffic Handling
BHCA Maximum traffic Base Station 20,000 Erlang 0.5% blocking, supports typically subscribers 0.15E subscribers 0.07E. Standard wire telephone payphone. Modems upto 4800 bits/sec
12.2 Voice DatInstruments supported
Number tones List tones Number three party conference calls Number announcements
Dial tone, special dial tone indication tone, call waiting tone, busy tone, unobtainable tone back tone, congestion tone, intrusion tone.
(Two sec. Segments played alternately each announcement.
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Appendix General Features
System configuration Addition, deletion change compact base station ports. Security: Pass word(upto characters) system administrator. Mobility management related data base-subscription, location registration, authentication, termination access rights class service. Billing: Data provided off-line billing. data includes cumulative local call units, cumulative call units, detailed billing calls, local calls both, demand, calling party number, called party number, duration call, time origin, number units, type call (local, STD, special services.) System health monitoring: based user friendly console display health cards Base stations. Remote OMC: operation carried remotely using modem connected DIU. Traffic Analysis: Number call attempts, successful call attempts each base station junctions.
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Appendix Supplementary Services
Automatic alarm call service Gives alarm ringing telephone registered time. Call completion supplementary services: Absent subscriber service: Diversion call operator announcement Automatic call back: Subscriber connected busy called number soon called number free. disturb: Incoming calls diverted announcement. Call offering supplementary services: Call diversion busy reply unconditional: Incoming calls diverted another subscriber number same when subscriber phone busy there reply unconditional. Call restriction supplementary service: Incoming call only: Subscriber only receive calls. Outgoing call only: Subscriber only make calls. Outgoing call- subscriber controlled call restriction: Dynamic barring. Outgoing call-administrator controlled call restriction: Barring international calls, calls, calls outside barring some special services. Incoming call- administrator controlled call restriction: Barring incoming calls from outside DIU. Charging charge debiting supplementary services: Printed record duration charge calls Detailed local call billing subscribers demand. Subscribers call charge meter: pulse provided wall external charge meter. Multi party supplementary services: Three party conference calling: Between wireless subscriber others wired wireless Rapid call supplementary services: Abbreviated dialling: Calling number with abbreviated code. Fixed destination call time out: going hook subscriber connected fixed destination number dialled within pre- defined time:
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Appendix Other Services
phone services Allows installation phone battery reversal only) phone battery reversal with pulses.) Malicious call identification Will record calling number junction number call will allow calling party disconnect. Ring back facility Subscriber indicated service check ringing telephone. Operator trunk offer Allows operator exchange into call already Temporary service subscriber Announcement incoming calls outgoing calls barred. Announcement circuits Allows announcement route congestion change exchange code, entitlement service special service. Hunting group subscribers Allows incoming calls land free subscribers group.
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Glossary Abbreviations
ADPCM CDMA DECT ETSI FDMA HDSL ISDN ITOS Kb/s Mb/s MC-TDMA PABX PSTN Adaptive Delta Pulse Code Modulation Base Station Compact Base Station Code Division Multiple Access Common Technical Regulations Dynamic Channel Selection Digital Enhanced Cordless Telecommunications DECT Interface Unit European Telecommunication Standards Institute Fixed Channel Allocation Frequency Division Multiple Access General Service Mobile High Density Subscriber Loop Integrated Services Data Network Incoming Trunk Outgoing Subscriber Kilo( Lines Kilo Lines Kilobits Second Kilohertz Kilometers Subscriber Lines Local Area Network Medium Access Protocol Megabits Second Multi-Carrier Time Division Multiple Access Megahertz Network Management System Operations Maintenance Centre Private Automatic Branch Exchange Private Branch Exchange Pulse Code Modulation Public Switched Telephone Network
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corDECT SMUX TDMA Remote Line Unit Rupees (Indian) Remote Service Unit Subscriber Multiplexer Technical Basis Regulations Time Division Multiple Access Watt Wireless Local Loop Wall
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Rev. 0.01 corDECT Table Contents Introduction. Importan

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