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ContentsHistory of CDMA Evolution path of CDMA
College of Telecommunications and Information Technology 1
Unit one
CDMA History and Evolution
History of CDMA• CDMA was developed originally by
Qualcomm and enhanced by Ericsson.• CDMA is characterized by high capacity
and small cell radius, employing spread-spectrum technology and a special coding scheme.
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History…• CDMA was adopted by the Telecommunications
Industry Association (TIA) in 1993. • The first CDMA cellular mobile communication
system was commissioned in Hong Kong in 1995.
• In September 1998, only three years after the first commercial deployment , there were 16 million subscribers on cdmaOne systems worldwide.
College of Telecommunications and Information Technology
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History…• By May 2001 there were 35 million
subscribers on cdmaOne systems worldwide and there are now 60 million.
• QUALCOMM owns a substantial portfolio of CDMA patents.
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11GG 22GG 33GG
Analog cellular
DDiiggiittaall cceelllluullaarr DDiiggiittaall cceelllluullaarr
VVooiiccee VVooiiccee //ddaattaa VVooiiccee // hhiigghh ssppeeeedd ddaattaa
AAMMPPSS CCDDMMAA 11XXRRtttt CCDDMMAA22000000
TTAACCSS GGSSMM GGPPRRSS WW__CCDDMMAA
8800’’ 11999922 11999999 22000011 22000033
Evolution of Mobile Communications System
AMPS: Advanced Mobile Phone SystemTACS: Total Access Communication SystemGPRS: General Packet Radio Services
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Evolution of CDMA2G
FL 3.09Mbps PDRL 1.8 Mbps PD
2.5G 3G
Voice
cdmaOneIS-95-A
••
• High Capacity Voice• 153 kbps PD• RF Backward
Comp.
CDMA20001X
CDMA20001X Rel A
• 2.4 Mbps PDRF Backward Comp.
CDMA2000 1xEV-
IS-95-BKoreaJapan
• Voice• 64 kbps Packet• RF Backward
Compatible
••• Backward Comp.
CDMA2000 1xEV- DO Rel
• FL 3.09 Mbps PD• RL 1.8 Mbps PD• Backward Comp.
CDMA2000 Rel D
cdmaOneIS-95-A
•
cdmaOneIS-95-A
•14.4 kbps CSD
•••
CDMA20001X
•••
CDMA20001X Rel. 0
• 307.2 kbps Packet• Backward Comp.
CDMA20001X Rel A
CDMA20001X Rel.A
•
CDMA2000 1xEV-
•
CDMA2000 1xEVDO Rel. 0
IS-95-BKoreaJapan
•••
IS-95-BKoreaJapan
•••
••
CDMA2000 1xEV- DO Rel
••
CDMA2000 1xEVDO Rev.A
•••
CDMA2000 1xEVDV Rel D
•••
D
•
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Unit TwoBasic Principles in CDMA
ContentsSpread spectrum technology principlesSpeech Coding TechnologyChannel Encoding Technology
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Defining Our Terms• CDMA Channel or CDMA Carrier or CDMA Frequency
– Duplex channel made of two 1.25 MHz-wide bands of electromagnetic spectrum, one for Base Station to Mobile Station communication (called the FORWARD LINK or the DOWNLINK) and another for Mobile Station to Base Station communication (called the REVERSE LINK or the UPLINK)
– In 800 Cellular these two simplex 1.25 MHz bands are 45 MHz apart– In 1900 MHz PCS they are 80 MHz apart
• CDMA Forward Channel
– 1.25 MHz Forward Link
• CDMA Reverse Channel– 1.25 MHz Reverse Link
• CDMA Code Channel– Each individual stream of 0’s and 1’s contained in either the CDMA Forward Channel
or in the CDMA Reverse Channel– Code Channels are characterized (made unique) by mathematical codes– Code channels in the forward link: Pilot, Sync, Paging and Forward Traffic channels– Code channels in the reverse link: Access and Reverse Traffic channels
45 or 80 MHz
CDMA CHANNELCDMA
ReverseChannel 1.25 MHz
CDMAForwardChannel 1.25 MHz
Spread Spectrum In CDMA
• The spread spectrum communications technology is an information transmission mode.
• The frequency bandwidth, occupied by signals, is far larger than the minimum bandwidth required for the information to be transmitted.
Spread Spectrum In CDMA• The spread width of the frequency band is
realized by means of coding and modulation.
• It is independent with the transmitted information data.
Spread Spectrum In CDMA…ORIGINATING SITE DESTINATION
SpreadingSequence
SpreadingSequence
InputData
RecoveredData
Spread Data Stream
Definition: Spread spectrum techniques ,employ a transmission bandwidth that is several orders of magnitude greater than the minimum required signal bandwidth.
Sender combines data with a fast spreading sequence, transmits spread data streamReceiver intercepts the stream, uses same spreading sequence to extract original data
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SHANON Formula
Spread Spectrum…
Where, C is capacity of channel, b/s B is signal bandwidth, Hz S is average power for signal, W N is average power for noise, W
C=B*log2(1+S/N)
It is the basic principle and theory for spread spectrum communications.
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Spread Spectrum…
User 1
Code 1
Composite
Time Frequency
+=
Direct Sequence CDMA
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CDMA a Spread-Spectrum System
Traditional technologies try to squeeze the signal into the minimum required bandwidth
Direct-Sequence Spread spectrum systems mix their input data with a fast spreading sequence and transmit a wideband signal
The spreading sequence is independently regenerated at the receiver and mixed with the incoming wideband signal to recover the original dataSpread Spectrum Payoff:
Processing Gain
Spread SpectrumTRADITIONAL COMMUNICATIONS SYSTEM
SlowInformation
Sent
TX
SlowInformationRecovered
RX
NarrowbandSignal
SPREAD-SPECTRUM SYSTEM
FastSpreadingSequence
SlowInformation
Sent
TX
SlowInformationRecovered
RX
FastSpreadingSequence
Wideband Signal
Spread Spectrum…
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1.25 MHz30 KHz
Power is “Spread” Over a Larger BandwidthMATHHAMMER
MATHHAMMER
Spread Spectrum…
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Many code channels are individually“spread” and then added together tocreate a “composite signal”
De-spreading…
• Any data bit stream can be combined with a spreading sequence• The resulting signal can be de-spread and the data stream
recovered if the original spreading sequence is available and properly synchronized
• After de-spreading, the original data stream is recovered.
ORIGINATING SITE DESTINATION
SpreadingSequence
SpreadingSequence
InputData
(Base Band)
RecoveredData
(Base Band)
Spread Data Stream(Base Band + Spreading Sequence)
Multiple codes
• Multiple spreading sequences can be applied in succession and then reapplied in opposite order to recover the original data stream.
• The spreading sequences can have different desired properties.• All spreading sequences originally used must be available in proper
synchronization at the recovering destination.
SpreadingSequence
ASpreadingSequence
BSpreadingSequence
CSpreadingSequence
CSpreadingSequence
BSpreadingSequence
A
InputDataX
RecoveredDataX
X+A X+A+B X+A+B+C X+A+B X+ASpread-Spectrum Chip StreamsORIGINATING SITE DESTINATION
Analogy…
• Whether in shipping and receiving or in CDMA, packaging is extremely important!
• Cargo is placed inside “nested” containers for protection and to allow addressing.
• The shipper packs in a certain order, and the receiver unpacks in the reverse order.
• CDMA “containers” are spreading codes.
FedE
xData Mailer
FedE
x
DataMailer
Shipping Receiving
• Spreading code chip speed is 1.2288Mc/s.• Spreading codes used:
Forward link—Walsh code & Short PN Reverse link—Long PN
Spreading Codes in CDMA
Spreading code selection is the key of spread Spectrum modulation!
Walsh Code Definition• The Walsh function is named after Walsh, the
mathematician who proved it an orthogonal function in 1923.
• Walsh code is an orthogonal square matrix. It is just composed of +1(0) and –1(1).
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0110
1100
1010
0000
10
000
Hn Hn
H2n = ___
Hn HnH1 H2 H4
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
WALSH CODES # ---------------------------------- 64-Chip Sequence ------------------------------------------ 0 0000000000000000000000000000000000000000000000000000000000000000 1 0101010101010101010101010101010101010101010101010101010101010101 2 0011001100110011001100110011001100110011001100110011001100110011 3 0110011001100110011001100110011001100110011001100110011001100110 4 0000111100001111000011110000111100001111000011110000111100001111 5 0101101001011010010110100101101001011010010110100101101001011010 6 0011110000111100001111000011110000111100001111000011110000111100 7 0110100101101001011010010110100101101001011010010110100101101001 8 0000000011111111000000001111111100000000111111110000000011111111 9 010101011010101001010101101010100101010110101010010101011010101010 001100111100110000110011110011000011001111001100001100111100110011 011001101001100101100110100110010110011010011001011001101001100112 000011111111000000001111111100000000111111110000000011111111000013 010110101010010101011010101001010101101010100101010110101010010114 001111001100001100111100110000110011110011000011001111001100001115 011010011001011001101001100101100110100110010110011010011001011016 000000000000000011111111111111110000000000000000111111111111111117 010101010101010110101010101010100101010101010101101010101010101018 001100110011001111001100110011000011001100110011110011001100110019 011001100110011010011001100110010110011001100110100110011001100120 000011110000111111110000111100000000111100001111111100001111000021 010110100101101010100101101001010101101001011010101001011010010122 001111000011110011000011110000110011110000111100110000111100001123 011010010110100110010110100101100110100101101001100101101001011024 000000001111111111111111000000000000000011111111111111110000000025 010101011010101010101010010101010101010110101010101010100101010126 001100111100110011001100001100110011001111001100110011000011001127 011001101001100110011001011001100110011010011001100110010110011028 000011111111000011110000000011110000111111110000111100000000111129 010110101010010110100101010110100101101010100101101001010101101030 001111001100001111000011001111000011110011000011110000110011110031 011010011001011010010110011010010110100110010110100101100110100132 000000000000000000000000000000001111111111111111111111111111111133 010101010101010101010101010101011010101010101010101010101010101034 001100110011001100110011001100111100110011001100110011001100110035 011001100110011001100110011001101001100110011001100110011001100136 000011110000111100001111000011111111000011110000111100001111000037 010110100101101001011010010110101010010110100101101001011010010138 001111000011110000111100001111001100001111000011110000111100001139 011010010110100101101001011010011001011010010110100101101001011040 000000001111111100000000111111111111111100000000111111110000000041 010101011010101001010101101010101010101001010101101010100101010142 001100111100110000110011110011001100110000110011110011000011001143 011001101001100101100110100110011001100101100110100110010110011044 000011111111000000001111111100001111000000001111111100000000111145 010110101010010101011010101001011010010101011010101001010101101046 001111001100001100111100110000111100001100111100110000110011110047 011010011001011001101001100101101001011001101001100101100110100148 000000000000000011111111111111111111111111111111000000000000000049 010101010101010110101010101010101010101010101010010101010101010150 001100110011001111001100110011001100110011001100001100110011001151 011001100110011010011001100110011001100110011001011001100110011052 000011110000111111110000111100001111000011110000000011110000111153 010110100101101010100101101001011010010110100101010110100101101054 001111000011110011000011110000111100001111000011001111000011110055 011010010110100110010110100101101001011010010110011010010110100156 000000001111111111111111000000001111111100000000000000001111111157 010101011010101010101010010101011010101001010101010101011010101058 001100111100110011001100001100111100110000110011001100111100110059 011001101001100110011001011001101001100101100110011001101001100160 000011111111000011110000000011111111000000001111000011111111000061 010110101010010110100101010110101010010101011010010110101010010162 001111001100001111000011001111001100001100111100001111001100001163 0110100110010110100101100110100110010110011010010110100110010110
Walsh Codes EXAMPLE:• Correlation of Walsh Code #23 with Walsh Code #59#23
0110100101101001100101101001011001101001011010011001011010010110
#59 0110011010011001100110010110011010011001011001100110011010011001
XOR 0000111111110000000011111111000011110000000011111111000000001111
• Correlation Results: 32 1’s, 32 0’s: Orthogonal!!
0 1 2 3 4 5 6 7 1 1
8 9 0 11 1 1 12 3 4 5
1 1 1 16 7 8 9
2 2 2 20 1 2 3
2 2 2 24 5 6 7
2 2 3 38 9 0 1
3 3 3 32 3 4 5
3 3 3 36 7 8 9
4 4 4 40 1 2 3
4 4 4 44 5 6 7
4 4 5 58 9 0 1
5 5 5 52 3 4 5
5 5 5 56 7 8 9
6 6 6 60 1 2 3
0123
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
4567
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
89
1011
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
12131415
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
16171819
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
20212223
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
24252627
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
28293031
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 0 1 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
32333435
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
36373839
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
40414243
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
44454647
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
48495051
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
52535455
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
56575859
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
60616263
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 0 1 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
1 1 1 11 0 1 01 1 0 01 0 0 1
1 1 1 11 0 1 01 1 0 01 0 0 1
0 0 0 00 1 0 10 0 1 10 1 1 0
Walsh Code Table
Walsh Code…
• A Mobile Station receives a Forward Channel from a sector in a Base Station.
• The Forward Channel carries a composite signal of up to 64 forward code channels.
• Some code channels are traffic channels and others are overhead channels.
• A set of 64 mathematical codes is needed to differentiate the 64 possible forward code channels.
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Walsh Code…• The Walsh code is also used to perform
orthogonal modulation on the reverse link.• Its use is chanalization.• Forward channels include Pilot, Sync,
Paging, and Forward Traffic channels.
Walsh Code…• Pilot channel is assigned Walsh code 0.• Sync channel is assigned Walsh code 32• Paging channel can be assigned Walsh
codes 1 to 7.• Forward traffic channels are assigned
random Walsh codes from the 55 (or 61 from paging channels) which are left.
Short PN• If we now have two BTS transmitting a set of
forward code channels each, how can we identify between the signals of the two?
• For this purpose we use the Short PN Sequence.
• The short PN is also used for digital modulation; QPSK modulation on the forward link and OQPSK on the reverse link.
Short PN Sequences
• Together, they can be considered a two-dimensional binary “vector” with distinct I and Q component sequences, each 32,768 chips long
• Each Short PN Sequence (and, as a matter of fact, any sequence) correlates with itself perfectly if compared at a timing offset of 0 chips
• Each Short PN Sequence is special: Orthogonal to a copy of itself that has been offset by any number of chips (other than 0)
IQ
32,768 chips long26 2/3 ms.
(75 repetitions in 2 sec.)
IQIQ
100% Correlation: All bits = 0
Short PN Sequence vs. Itself @ 0 Offset
IQIQ
Orthogonal: 16,384 1’s + 16,384 0’s
Short PN Sequence vs. Itself @ Any Offset
Unique Properties:
The two Short PN Sequences, I and Q, are 32,768 chips long
Short PN…
1 0010 0110 1101 1011 0100 1011 0110 1111 1111 110
10 0 00 0100 100
1 1001 000
0 100
p1 p2 p3 p4
p4 p5 p2 p3
p2 p3
p4
p5 = p1 + p4
p4
Short PN…The PN sequences are deterministic and periodic.
– The length of the generated string is 2n-1, where “n” is the number of elements in the register
– The number of ones in the sequence are equal to the number of zeros plus 1
Short PN…
• Each Sector in each Base Station is transmitting a Forward Traffic Channel containing up to 64 forward code channels.
• These Short PN Sequences can be used in 512 different ways in a CDMA system. Each one of them constitutes a mathematical code which can be used to identify a particular sector.
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A B
Up to 64Code Channels
Up to 64Code Channels
Long PN• The main function of the Long PN
Sequence is found on the reverse link.• Since all users can be on the same
frequency, it is easy to confuse for the BTS.
• The long PN is used to identify and differentiate the users on the reverse channel.
Long PN Sequence
• Each mobile station uses a unique User Long Code Sequence generated by applying a mask, based on its 32-bit ESN, to the 42-bit Long Code Generator which was synchronized with the CDMA system during the mobile station initialization.
• Generated at 1.2288 Mcps, this sequence requires 41 days, 10 hours, 12 minutes and 19.4 seconds to complete.
• Portions of the User Long Codes generated by different mobile stations for the duration of a call are not exactly orthogonal but are sufficiently different to permit reliable decoding on the reverse link.
Long Code Register (@ 1.2288 MCPS)
Public Long Code Mask (STATIC)
User Long CodeSequence
(@1.2288 MCPS)
1 1 0 0 0 1 1 0 0 0 E S N
AND
=S U M
Modulo-2 Addition
Long PN…• The CDMA system must be
able to identify each Mobile Station that may attempt to communicate with a Base Station.
• One binary digit sequence called the Long PN Sequence (or Long PN Code) is defined for the purpose of uniquely identifying each possible reverse code channel.
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RV Trafficfrom M.S.
#1837732008 RV Trafficfrom M.S.
#1997061104
RV Trafficfrom M.S.
#1994011508System AccessAttempt by M.S.
#2000071301(on access channel #1)
Coding in CDMA
• Data transmission efficiency has been a critical issue in the development of telecommunication networks for a long time.
• so it is extremely important to use different speech coding techniques.
Coding…• To date, researchers have been studying
this issue in two ways.• Study new modulation methods and
techniques to improve channel transmission bit rate.
• Compress source encoding bit rate.
Speech coding…
Speech coding is essential because we have to use the available bandwidth efficiently.
current CDMA systems employ an effective voice encoding technique, Qualcomm Code Excited Linear Prediction (QCELP).
The other kind of coding widely used is EVRC(Enhanced variable rate coding)
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Channel Encoding Technology
Due to the peculiarity of mobile communication systems, high requirement is imposed on channel encoding.
The aim of channel encoding is to minimize error during transmission.
Some of the encoding technologies are:Convolutional Viterbi Turbo
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Unit ThreeCDMA Network and Its
Elements
ContentsNetwork Architecture Description of Network elements
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CDMA Network Architecture
2G/3G Terminals
Abis
Abis
Abis
PSTN/PLMN
BSC/ PCF (1X)
Internet
Router Router
IP
IP
BTS ( IS-95)
BSC ( IS-95)
AbisE1
Um
IS95
Um
IS2000E1 STM-1
E1 STM-1
Ethernet
MSC/VLR HLR/AUC
PDSN/FA
AAA
HA
OMC
SC
WINBTS ( IS-9
5)
BSC/ PCF (1X)
BTS ( 1X)
BTS ( 1X)
E1
Server
Ethernet
41College of Telecommunications and
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Description of Network elements
• BTS:BTS is in charge of wireless transmission.
• The BTS is the network element responsible for maintaining the air interface and minimizing the transmission problems.
Air interface signalingSpeech processingThe base station can contain several TRXs
(Transceivers)
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Description…
• The BSC is the central network element that controls the radio network. The important functions of the BSC are:Connection establishment between the AT and
the core network elements.Statistical data collection and control of the
BTS’s and the AT’s.Signalling support in the air and with the core
network elements.Mobility management:
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Description of Network elements• MSCe (MSC emulation)
– The MSCe (MSC emulation) is a set of multiple logic functional entities.
– It supports mobility management, and provides call control, connection, VLR and some service functions.
– It is the core device providing call control and service for CS real-time voice/data services in this phase.
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Description…• MGW (Media gateway )
– The MGW (Media gateway ) provides the packet switching environment in the core network , and the circuit switching environment in the PSTN with the support for bearer services.
• HLRe (HLR emulation)– On the base of HLR in 2G, the IP signaling
interface is added to the HLRe to manage the user’s voice service , data service features , user location and accessibility information.
45College of Telecommunications and
Information Technology
Unit FourUnderstanding CDMA channels
ContentsDefining Channel term in CDMAChannel Structures
CDMA IS-95 and CDMA2000-1xCDMA2000-Ev-DO
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Defining Channel term in CDMA
• Channel: An individually-assigned, dedicated pathway through a transmission medium for one user’s information.
• The transmission medium is a resource that can be subdivided into individual channels according to the technology used.
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FrequencyTime
Power
FrequencyTime
Power
FrequencyTime
Power
FDMA
TDMA
CDMA
.
Defining Channel…–Code Channels are characterized (made unique)
by mathematical codes–Code channels in the forward link: Pilot, Sync,
Paging and Forward Traffic channels–Code channels in the reverse link: Access and
Reverse Traffic channels –The bandwidth of a CDMA channel is constant
and it is 1.25MHz.
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Channel Structures in CDMA IS-95 and 2000-1x
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Pilot Channel
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Transmitted constantly by Base station to provide a reference for all mobile stations.All Base Stations share the same Short PN sequence, but are distinguished by the different phase offsets. Used for comparison of Signal strength between different base stations to decide when to perform the Hand off.
Sync Channel
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(Acquired Pilot)
Sync Channel
Used to provide Basic system parametersUsed during system acquisition stageBit rate is 1.2 kbpsUses Walsh Code 32
Paging Channels
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Paging Channel
The Paging channel carries information to allow the network to supply display information to be displayed by the MSThere is one paging channel per sector per CDMA carrierThe Paging Channel uses Walsh code - 1Two rates are supported: 9.6 kbps and 4.8 kbps
Reverse Access Channels
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Access channel
Used by the mobile station to:– Register with MSC (Power On)– Originate a call– Respond to a Paging Channel message– Has a fixed data rate of 4.8 kbps
Each Access Channel is associated with only one Paging Channel
Reverse Traffic Channels
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Reverse Traffic Channel
Used when a call is in progress, to send:–Voice traffic from the subscriber–Response to commands/queries from the base station –Requests to the base station
Forward Channel Structure of Ev-Do
ControlMediumAccessControl
Pilot Traffic
ReverseActivity Channel
ReversePower
Control(RPC)
Forward
DRC Lock
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Sharing the Forward Traffic Channel
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DRCLockDRCLockDRCLockDRCLock DRCLockDRCLock DRCLockDRCLock
DRCLockDRCLock DRCLockDRCLock DRCLockDRCLock DRCLockDRCLock
Forward Link Summary Forward link transmission is organized as
26.66…ms frames. 1 frame=16 slots, where 1 slot=2048 chips=1.67 ms.
The transmission rate (38.4 kbps ~ 2457.6 kbps) is the rate requested by AT,
Channels are mostly in TDM mode. Traffic data are dedicated to a single AT at
any given instant of time.
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Reverse Channel Structure
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Reverse Link Summary 1 packet = 26.67 ms, 1 slot = 2048
chips, 1 frame=16 slots Supporting data rates from 9.6k to
153.2K. Channels are in CDM mode Two main channels Traffic channel and
Access channel. Traffic channel = Pilot + MAC + Data +
ACK Access channel = Pilot + Data Supporting reverse closed & open loop
power controlsCollege of Telecommunications and
Information Technology59
Unit FiveCDMA Key Technologies
ContentsPower controlHandoff
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Power control in CDMA
There are four types of power control in CDMA
- Reverse open loop power control
- Reverse closed loop power control
- Reverse outer loop power control
- Forward traffic channel power control
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Reverse Open Loop Power Control
• The mobile station makes a coarse initial estimation of the required transmit power, based upon the total received power.
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Mobile BTSReverse Open Loop
Power Control
Reverse Closed Loop Power Control
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Mobile BTSSignal StrengthMeasurement
Setpoint
or
Reverse Closed LoopPower Control
Compensates for asymmetries between the forward and reverse pathsEach command requests a 1dB increase or decrease of the mobile station transmit powerTransmitted 800 times per second (i.e power control bit is transmitted every 1.25ms )
Reverse Outer Loop Power Control
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FER
Mobile BTS BSCReverse Outer
Loop Power Control
Signal StrengthMeasurement
Setpoint
orReverse Closed Loop
Power Control
Most gradual form of reverse link power control
–Setpoint is varied according to the FER on the Reverse Traffic Channel
–Sampled at a rate of 50 frames per second (20 ms / frame)
–Setpoint adjusted every 1-2 seconds
Forward Traffic Channel Power Control
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The base station slowly decreases power to each mobile station. As the FER (determined at the mobile station) increases, the mobile station requests a Forward Traffic Channel power increase.
Summary of All Power Control Mechanisms
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All types of power control work together to minimizes power consumption at the mobile stations.This increases the overall capacity of the system transmit power.
Handoff in CDMA
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Handoff is the process by which a mobile station maintains communications with the Mobile Switching center (MSC), when traveling from the coverage area of one base station to that of another.Handoffs keep the call established during the following conditions:
–Subscriber crosses the boundaries of a cell
–Subscriber experiences noise or other interference above a specified threshold
CDMA Handoff Classification
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Duringa Call
Idle Handoff
Soft Handoff
Softer Handoff
CDMA-to-CDMA Handoff
Inter-System Soft Handoff
CDMA-to-Analog Handoff
While in the Idle State
PN 104
PN 108
A
Paging Channel Msgs
Sync Channel Msg
104108
Ec/Io
It’s neither soft nor hardhandoff!
CDMA Idle Handoff
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PN 104
PN 108
APaging Channel M
sgs
Sync Channel Msg
104108
Ec/Io >3dB
CDMA Idle Handoff…
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Soft Handoff
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Cell SiteB
Cell SiteA
PSTNMSC
Between sectors of different cells
Soft Handoff: the mobile station starts communications with a target base station without interrupting communications with the current serving base station.
Can involve up to three cells simultaneously and use all signals
Softer Handoff
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alpha
beta
gamma
Handoff is between sectors of the same cellMay happen frequentlyMSC is aware but does not participateSignals received at both sectors can be combined for improved quality
How many CE will be used?
Inter-System Soft Handoff
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Mobile Station starts communications with a new cell controlled by a different BSC while still communicating with the cell controlled by the source BSC.
CDMA-to-CDMA Hard Handoff
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A(ƒ1)
PSTN MSCBSC
B(ƒ2)
A
PSTNMSCBSC
B
MSCBSC
T1 or E1 LinksTIA/EIA-41D
Between cells operating on different frequencies
Between cells that could be on the same frequency, but which are subordinated to different MSC
Unit Six Interfaces and Protocols
Contents InterfacesProtocols and signalingTypical CDMA Network Architecture
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Interfaces in CDMA 20001x
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Interfaces of 1xEVDO
Source Access Network (AN)
Target Access Network (AN)
Access Terminal (AT)
AN AAA
PDSNPCF
A8
A9
A10
A11
A12A13Air Interface
signaling
service
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Interfaces…
• The A1 interface carries signaling information between BSC and MSC.
• The A2 interface mainly carries 64/56K PCM between BSS and MSC.
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Interfaces…
• A3 interface is used to support the soft handoff(interconnection between BSCs required) between BSSs when the MS is in the traffic channel status. A3 interface is divided into two parts: A3 signaling interface and A3 traffic interface.
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Interfaces…
• A7 interface is used to support the handoff between BSSs when the MS is not yet under the control of traffic channel status, and support the control stream when the MS undergoes soft handoff between BSSs and new service needs to be established.
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Interfaces…
• A8 & A9 interfaces are adopted to carry service data and signaling respectively between BSC and PCF.
• A10 & A11 interfaces are adopted to carry service data and signaling respectively between PCF and PDSN.
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Interfaces…
• A12 interface carries signaling information of access authentication (only include 3 messages: access request, access accept, and access reject).
• A13 interface exchanges signaling when AT is roaming between source AN and target AN.
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UDP
Protocols & signaling
IP
TCP SCTP
SIP/SIP-T H.248
SCCP
SUA M3UA
RTP BSSAP MAP
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Protocols & signaling…SignalingSignaling•It is the dialog language for the communication between various parts of the telecom network. •Signaling system includes a set of signaling and operation procedure.
•Signaling system is the collection of software and hardware which generate 、 transmit 、 receive and recognize the signaling. 84
College of Telecommunications and Information Technology
Signaling System SS7 is the predominant signaling system for the Public Switched Telephone Network (PSTN) and also Public Land Mobile Networks (PLMN).
SS7 defines the procedures for setting-up, managing and clearing down calls between subscriber(circuit-related signaling ), as well as non circuit-related signaling.
Protocols & signaling…
85College of Telecommunications and
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Protocols & signaling…
MSCe MSCe
MGW
MGW
MGW
Control Signalin
g Over IP
H.248 H.248
Media Over
IP
H.248 : used in MSCe to control the MGW implement voice bearing on the packet network. They reflect the idea of separating control function from the media conversion function.
MGW
MGW
What is H.248?
86College of Telecommunications and
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Protocols & signaling…
• Command is used to operate and manage logical entities (context and terminations). The protocol defines eight commands, of which the majority is used for the MGC (MSCe) to control MG (MGW).
• All of the commands in one action control the same context.
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Protocols & signaling…
Add
Modify
Subtract
Move
AuditValue
AuditCapabilities
Notify
ServiceChange
MSCe MGW
H.248 commands
88College of Telecommunications and
Information Technology
Protocols & signaling…SIP: Session Initiation Protocol• SIP is a multimedia communication protocol
established by IETF.• It is a text-based application-layer control
protocol independent of lower-layer protocols, designed to establish, modify and terminate two-party or multi-party multimedia sessions over the IP network.
89College of Telecommunications and
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Protocols & signaling…SIP supports proxy, redirect and user location registration functions. It also supports user mobility. it can support and be applied to voice, video and data services. In addition, it can be applied to characteristic services like Presence and Instant Message (similar to MSN).
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Protocols & signaling…
Requests:• INVITE – initiate call• ACK – confirm final
response• BYE – terminate call• CANCEL – cancel
search/ring
Responses:
• 1xx – Informational
• 2xx – Successful
• 3xx – Redirection
• 4xx – Request Failure
• 5xx – Server Failure
• 6xx – Global Failure
SIP message types
91College of Telecommunications and
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Protocols & signaling…
Blue parts are SIGTRAN (Signaling Transport).
IP
SCTP
SUA
M2PA M3UA
MTP3
BSSAP
SCCP
TCAP
MAP
H.248 TUP/ISUP
M2UA
MTP3
SS7 SCCP-User Adaptation Layer SS7 MTP2-User Peer-to-Peer Adaptation Layer
SS7 MTP3-User Adaptation Layer
SS7 MTP2-User Adaptation Layer
IETF SIGTRAN Protocol Model
92College of Telecommunications and
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Protocols & signaling…
• SCTP: Stream Control Transmission Protocol
• A reliable connection-oriented transport protocols
• At the same layer as TCP and UDP in network model
• SCTP is designed to transport PSTN signaling messages over IP networks
SCTP Protocol
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Protocols & signaling…
• An association is an SCTP connection. • The creation of an association is initiated by an
SCTP user. To guarantee the security and prevent malicious attacks, the cookie mechanism is adopted during the starting of an association.
• The connection creation and release is used for the transition of the connection status and abnormality handling.
Association
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Protocols & signaling…
• M3UA is the adapter layer for SS7 MTP3 user. • Implement the interconnection between SS7
over TDM and IP• M3UA provides powerful routing function
M3UA Protocol
95College of Telecommunications and
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Unit Seven Comparing CDMA to Other
Cellular Technologies
ContentsAdvantages provided by CDMADisadvantages of CDMA
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High privacy, hard to wiretapping
Spread code
Informationsignal
TX
Demodulatedsignal
RX
Spread code
Spread signalSignal can be sent belowthe noise .
Advantages of CDMA
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Good voice quality, uses 8k QCELP, 13K QCELP,8k EVRC, voice coding - the best coding method in the world.
Voice quality(MOS) 64k
PCM13kGSM
8k QCELPCDMA
13k QCELPCDMA
8kEVRCCDMA
Advantages…
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Frequency reuse factor is 1;network design and expanding becomes much easier.
Advantages…
AMPS, D-AMPS, N-AMPS
CDMA
30 30 10 kHz
200 kHz
1250 kHz
1 3 1 Users
8 Users
20 Users1
1
11
11
11
111
111
1 23
4
432
56 17
Typical Frequency Reuse N=7
Typical Frequency Reuse N=4
Typical Frequency Reuse N=1
GSM
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Call drop rate is very low due to soft handoff
Advantages…
Soft handoff Hard handoff
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Good Power Control and voice activation make the MS Power low, healthy for body—green mobile phone.
Advantages…
Mean Power Max Power
GSM: 125mW 2W
CDMA: 2mW 200mW
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Large coverage: Almost 2 times more than GSM.
Example: cover 1000 km2
GSM needs 200 BTS CDMA needs only 50 BTS Attention: exact result need “Link Budget ”
Advantages…
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High spectrum capacity , 8--10 times more than AMPS,4—6 times more than GSM
FrequencyTime
Power
FrequencyTime
Power
FrequencyTime
Power
FDMA
TDMA
CDMA
FDMA---Different user use different frequency:TACS,AMPSTDMA---Different user use different time slot of one frequency :GSM 、 DAMPSCDMA---Different user use same frequency at the same time, but with different spreading code
Advantages…
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Disadvantages of CDMA
Channel pollution (self jamming)Signals from too many cell sites are present
at the subscriber’s phone but none of them happens to be dominant.
the quality of the audio signal degrades leads to customer dissatisfaction and service
loss of the operator.
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Disadvantages…Lack of international roaming capabilities
compared to GSM, there is the lack of international roaming capabilities.
the ability to upgrade or change to another handset is not easy with this technology.
the network service information for the phone is put in the actual phone unlike GSM which uses SIM card for this.
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Disadvantages…Near-Far problem
If the nearer transmitter transmits a signal that is orders of magnitude higher than the farther transmitter: then the SNR for the farther transmitter may
be below detect ability farther transmitter may just as well not
transmit.CDMA highly depends on power control
unlike other networks like GSM.College of Telecommunications and
Information Technology106
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