Post on 28-Oct-2014
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MembersAman ShakyaBishal PoudelKrishna Kumar GuptaSandep Gupta
APresentation on CDMA 2000
and IP CDMA
R. Z. Ziemer, Colorado Springs, CO 2May 28-June1, 2001
Why CDMA?• Higher capacity• Improved performance in multipath by diversity• Lower mobile transmit power = longer battery life– Power control– Variable transmission rate with voice activity detection
• Allows soft handoff• Sectorization gain• High peak data rates can be accommodated• Combats other-user interference = lower reuse factors
CDMA Evolution Paths
2Mbps
153.6kbps
CDMA1xRTT
CDMA 1xEV-DV
CDMAIS-95
CDMA1xEV-DO
CDMA3x 5x
2G 2.5G 3G
9.6kbps
1993, the first CDMA standard IS-95 was issued; In 1995, CDMA technology was put into
commercialization in Hong Kong and America on large scale;
In April, 2001, China Unicom began to construct CDMA networks—the largest in the world (about 70Million line now);
At present, CDMA commercial networks are established in about 40 countries or area, almost 20% of all users in the world.
CDMA-Its History & Status
CDMA PCS 1900 MHz Spectrum Usage
Guard Bands
Forward link (i.e., cell site transmits)Reverse link (i.e., mobile transmits)1850 MHz
BTA
BTA
BTA
BTA
BTA
BTA
Paired Bands
MTA BTAMTABTA MTAMTA
1910 MHz
1930MHz
1990MHz
Data Voice
A D B E F C A D B E F C
15 51010 1515151515 555 55
Licensed Licensed
Unlicensed
0
Channel Numbers 299
300
400
699700
800
900
1199 0
299300
400
699700
800
900
1199
CDMA Frequency ChannelAssignment at 800 MHz Cellular
IS-95 Recommends to Start CDMA Deployment with Either the Primary or the Secondary Channel
1
334
667
991
1023
333
666
715
799
716
ChannelNumbers
A Band B Band A’A” B’
1019 37 78 119 160 201 242 283 384 425 466 507 548 589 630 691 777
CDMA A-Band Carriers CDMA B-Band Carriers
8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 9 9 8
* **** Requires frequency coordination with
non-cellular interferers
** Requires frequency coordination with A-band carrier
A Band Primary Channel 283A Band Secondary Channel 691
B Band Primary Channel 384B Band Secondary Channel 777
736
Frequency Reuse
CDMA (IS-95)frequency reuse = 1 TDMA (IS-136)
frequency reuse = 7
Walsh Codes
• 64 Sequences, each 64 chips long– A chip is a binary digit (0 or 1)
• Each Walsh Code is Orthogonal to all other Walsh Codes– This means that it is possible to recognize and
therefore extract a particular Walsh code from a mixture of other Walsh codes which are “filtered out” in the process
– Two same-length binary strings are orthogonal if the result of XORing them has the same number of 0s as 1s
Coding Process on CDMA Forward Channels
WALSH19
BTSPilot Walsh 0
Walsh 19
Paging Walsh 1
Walsh 6
Walsh 11
Walsh 20
Sync Walsh 32
Walsh 42
Walsh 37
Walsh 41
Walsh 56
Walsh 60
Walsh 55
PN OFFSET 116BTS
PN OFFSET 226BTS
PN OFFSET 510BTS
S PN
372
x
x
xPN OFFSET
ANALOG
SUM/MUX PN OFFSET 372
d1 d2
t t t
d3
transmission receivingRaker combination
noise
Rake Receiver (1)
Rake Receiver (2)
Correlator 1
Correlator 2
Correlator 3
Search Correlator
Com
bine
r
To De-Interleaver, Viterbi Decoder
Multipath Delay Components
( 150 ms > Dt > 1ms)
Rake receiver can isolate multipath spaced > 1 chip length.
Rake Receiver (3)
• Handset uses combined outputs of the three traffic correlators “rake fingers”
• Each finger can independently recover a particular PN offset and Walsh code
• Fingers can targeted on delayed multipath reflections, or even on different BTSs
• Searcher continuously checks pilots
Intelligent Vocoder
Power ControlAutonomous power controlOn the Uplink tells the MS to vary it’s transmitted power
inversely with the power level it receive from the BS.
Direct power controlOn the Uplink measures Eb/No at the base station and sends
power Control Bits over the Downlink to the MS to instruct the MS to either increase or decrease its transmit power.
Downlink power controlAttempts to use minimum power needed to meet to a Frame
Error Rate (FER) threshold at the MS s.
Coverage
• The coverage radius is 2 times
of standard GSM.• Coverage of 1000 km2: GSM
needs 200 BTS 's, while CDMA
requires only 50.• Under the same coverage
conditions, the number of BTS
's is greatly decreased
Simple project design & convenient capacity expansion
13
2
4
3
2
4
24
4
1
2
3
1
4
2
31
4
GSM: N=4 Frequency reuse
11
1
1
11 1
11
1
1
1
1
1
1
1
11
1
11
1
Simple Network Planning
CDMA: N=1Frequency reuse
Functions of the CDMA Reverse Channels
• There are two types of CDMA Reverse Channels:– TRAFFIC CHANNELS are used by individual
users during their actual calls to transmit trafficto the BTS.
– ACCESS CHANNELS are used by mobile stations not yet in a call to transmit registration requests, call setup requests, page responses, order responses, and other signaling information
Coding Process on CDMAReverse Channels
• Each mobile is uniquely identified by the User Long Code, which it generates internally.
• All mobile stations transmit simultaneously on the same 1.25 MHz wide frequency band.
• Any nearby BTS can dedicate a channel element to the mobile station and successfully extract its signal.
• Mobile stations also use the other CDMA spreading sequences, but not for channel-identifying purposes.
• Short PN Sequences are used to achieve phase modulation.
• Walsh Codes are used as Orthogonal Modulation to give ultra-reliable communications recovery at the BTS.
Benefits of the cdma2000 1x Standards
• Increased mobile standby battery life (via Quick Paging Channel)
• Total backward compatibility to reuse switch and call processing features
• 2-3 dB better coverage• High speed 153.6 kbps packet data capabilities• cdma2000 1x = 1.25 MHz Radio Transmission
Technology
Example of cdma2000 1x Network
HandOff in CDMA:
CDMA channel Structure• CDMA Forword Channels:
– 64 Walsh codes channels:• 1 paging channel• 1 sync channel• 1 paging channel• Unsed channels up to 6 channels• Traffic channels: 55 channel at least
Forword traffic Channel Generation 8Kb Vocoding
23
24
25
26
27
CDMA Advantages
• Spread Spectrum• Soft & Softer Handoff• Rake Receiver• Variable Rate Vocoder• High quality voice• Power Control• Coverage• Simple Network Planning• Green Handset• Smooth migration to 3G and the operator’s benefit is
protected at the most
Why IP CDMA
• Expensive Transmission Network• Slow provisioning of new services• Complicated Network Architecture• Distributed Operation & Maintenance
Migration to IP CDMA
It occurs in two stages• from legacy circuit-switched MSC based
network solution to Soft switch based solution.
• from Soft switch based solution to IMS based solution.
1.Soft switch based solution• Intended to facilitate a smooth migration of the present Circuit Switched
MSC based CDMA 2000 1x Network to a Network based on IP.• CDMA2000 1x core network based on IP separates services from control
and call from bearer.• It can be interconnected with other CDMA2000 Networks and PSTNs /
PLMNs and is compatible with existing CDMA 2000 1x mobile networks.
Functional elements involved
• Soft switch– Contains emulation for functionality of MSC,HLR & SCP for
IP Based CDMA 2000 1x Core Network.– Provides support for existing Mobile Stations an IP core
network environment.– Also supports the features and capabilities provided in a
legacy network in a manner transparent to the user.
Functional elements involved
• Media Gateway (MGW)– Acts as an Inter working Function between circuit switched and packet
switched networks and provides the interface for the media path conversion between the circuit network and circuit clients, and the packet network and its clients.
– It is responsible for voice and circuit switched data services bearer in the core network, implements service transmission and format conversion within mobile networks or between mobile networks and fixed networks.
– With the help of Soft switch, MGW provides basic services, supplementary services and intelligent services.
Functional elements involved
• Signaling Gateway (SGW)– It provides the necessary interworking of various
elements like MSC, HLR , SCP,MGW, SS7 systems, PSTN etc.
– It converts SS7 signaling in the PSTN/PLMN network to IP packets to be carried over the IP network.
– It transports SS7 messages received from PSTN,PLMN etc over E1 to CDMA soft switch and Media Gateway and it also transports signaling messages (SS7 or RTP) received from RAN(BSC).
Functional elements involved
• IP RAN– The Radio Access Network comprising of BTS and
BSC– supports IP in the backhaul– can directly interface, for signaling, with the IP
Soft switch rather than through the Media Gateway.
2. IMS(IP Multimedia Subsystem) based solution
• IMS (MMD-Multi Media Domain) supports only IP-based signaling and provides support for SIP capable Mobile Stations in an IP core network environment.
• The IMS standards are still evolving and no commercial deployment of IMS-based network is expected.
Features Of IP CDMA
• Soft switch– Separation of the control from bearer– Control and management functions of resources on the
MGW– Access to the IP based RAN in the IP transmission mode– The underlying packet transport technology is Internet
Protocol (IP)– Interfaces & Signaling, Inter Working, Protocols and
Interaction with other IN network elements are as per standard specification referred by3GPP2, IETF, ITU etc.
– Integration with IP Multimedia Sub System (IMS)
Features Of IP CDMA
• Other Features– Lawful Interception• Capturing, monitoring and recording of a specific data
stream.• Filtering and storing call related information for targets
in a separate file, for transferring to Law Enforcement Agencies.
• Interfaces to circuit switched MSC based CDMA Network & PSTN Network– capability to connect with other circuit switched
based PSTN switch / MSCs with an appropriate interface.
– support IETF standards like SIGTRAN, SIP, SIP-T, etc. so as to be easilyinteroperable with other wireless and wireline next generation networks.
• Interoperability– field deployed commercially across multiple
countries and networks with various technologies /vendors of MGW, Soft switch and signaling Gateway, legacy Network etc.
• Billing/Charging– capable of generating CDRs in desired format for
end user billing as well as inter carrier accounting details.
• Network Management System (NMS)– possible to have remote workstations, with
complete GUI tools for operation & management of the system at the remote locations.
– Support interface like SNMP, CORBA, TCP / IP etc., to enable it to work with a remote NMS.
Thank You