Introduction to WCDMA Fundamentals Nokia
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Transcript of Introduction to WCDMA Fundamentals Nokia
© Nokia Siemens Networks
WCDMA Technology andRadio Fundamentals
2 © Nokia Siemens Networks
Agenda
1. WCDMA Fundamentals– Introduction– WCDMA Network Architecture and Interfaces– Basic Concepts: Spreading, Processing Gain– WCDMA codes– Radio Fundamentals : RSCP, Ec/Io– WCDMA channels
2. WCDMA Network Dimensioning and Planning – WCDMA Network Dimensioning Process Overview– Cell Breathing Concept– Input Planning Parameters– Link Budget– 3G Planning : Key Results analysis
3 © Nokia Siemens Networks
What 3G can offer to End Users..
6 © Nokia Siemens Networks
Drivers for 3G
evolution
Drivers for 3G evolution and broadband mobile
Demand model
• Analogies from fixed broadband usage for both business and consumers
• Average DSL user consumes today 1-2 GB per month (data, voice, video)
Advances in acc. Tech. development
• Flarion, WiMax, 3GPP2 camp, WLAN
• Technology politics (e.g., Korea-US-Japan-China- Europe)
Changing service & underlying technology mix
• Refarming
• New spectrum
Spectrum and regulatory drivers
• Volume & ARPU shift from voice to data
• Circuit switched to packet data (VoIP, IMS)
• Internet as a major source for mobile services
Price/performanceof technology
• Efficient use of spectrum
• Improved broadband experience
7 © Nokia Siemens Networks
GSM evolution to 3G
GSM9.6kbps (one timeslot)GSM DataAlso called CSD
GSM
General Packet Radio ServicesData rates up to ~ 115 kbpsMax: 8 timeslots used at any one timePacket switched; resources not tied up all the timeGSM / GPRS core network re-used by WCDMA (3G)
GPRS
HSCSD
High Speed Circuit Switched DataDedicate up to 4 timeslots for data connection ~ 50 kbpsGood for real-time applicationsInefficient -> ties up resources, even when nothing sent
EDGE
Enhanced Data Rates for Global EvolutionUses 8PSK modulation3x improvement in data rate on short distancesCan fall back to GMSK for greater distancesCombine with GPRS (EGPRS) ~ 384 kbpsWCDMA
8 © Nokia Siemens Networks
New services demand higher speed
Non-real time background and
narrowband streaming
Interactive, medium bit rate
streaming, business
connectivity
Real time connections,
efficient business connectivity
HSPA1-14Mbps
WCDMA128-384
kbps
EDGE80-160kbps
GPRS30-40kbps
GSM10-40kbps
Video sharingVideo
telephonyReal time IP
Real time games
High speed mobile
intranet
Faster business
connectivityFaster
streamingFaster
content downloadWeb browsing
Mobile intranet accessVideo
streamingVideo sharingVoice
SMS
MMSWAP
DownloadPresence
Audio streaming
Close to WLAN bit rates and
high efficiency
9 © Nokia Siemens Networks
What can be done to meet Demands
GSMWCDMA
CDMA
Flarion Flash-OFDMBWA
WiMAX (802.16-2005)
NxEV-DO
3.9 G HSPA
EV-DO rev. A, Rev B
I-HSPA
UMTS-TDD
WLAN (unlicensed)
EDGE Evolution
WiMAX (802.16-2004)
Mobile
’05 ’06 ’07 ’08 ’09 ’10
10 © Nokia Siemens Networks
Standardisation of 3G Cellular Networks
11 © Nokia Siemens Networks
Standardisation of 3G cellular networks
ITU (Global guidelines and recommendations)• IMT-2000: Global standard for third generation (3G) wireless communications
3GPP is a co-operation between standardisation bodiesETSI (Europe), ARIB/TTC (Japan), CCSA (China), ATIS (North America) and TTA (South Korea)
• GSM, EDGE• UMTS
– WCDMA - FDD– WCDMA - TDD
3GPP2 is a co-operation between standardisation bodies
ARIB/TTC (Japan), CCSA (China), TIA (North America) and TTA (South Korea)• CDMA2000
– CDMA2000 1x– CDMA2000 1xEV-DO
12 © Nokia Siemens Networks
Structure of 3GPP
TSG STRUCTURE
13 © Nokia Siemens Networks
UMTS Release 99
UMTS Release 4
UMTS Release 5
UMTS Release 6
• UMTS CN• UTRAN & WCDMA
• Low chip rate TDD mode
• High Speed Downlink Packet Access (HSDPA)• Wideband AMR• Initial phase of the IP Multimedia Subsystem• IP transport in the UTRAN etc.
• FDD Enhanced Uplink (HSUPA)• IMS Phase 2• Wireless LAN/UMTS Inter-working• Multimedia Broadcast/Multicast Service (MBMS)
19992001
2002
2005
UMTS Releases
UMTS Release 7• 64 QAM modulation• MIMO• HSPA+
UMTS Release 8 • LTE
2007
2008
15 © Nokia Siemens Networks
Downlink peak rate
Network Latency
Uplink peak rate
Bandwidth
Standard
3G evolution – performance
Spectral efficiency, DL
Spectral efficiency, UL
WCDMA R99
3GPP
5.0 MHz
100-200 ms
384 kbps
384 kbps
0.16 bps/Hz
0.16 bps/Hz
WCDMA HSPA
3GPP
5.0 MHz
<50 ms
1.8-10.7 Mbps
1-4 Mbps
0.2-0.8 bps/Hz
0.25 bps/Hz
3.9 G estim.
3GPP
1.25-20 MHz
<10 ms
Up to 100 Mbps
Up to 50 Mbps
1.6-2.5 bps/Hz
0.6-0.8 bps/Hz
© Nokia Siemens Networks
Market Trends for 3G Technology
17 © Nokia Siemens Networks
World Cellular Market
18 © Nokia Siemens Networks
Global growth of UMTS HSPA Technology
19 © Nokia Siemens Networks
UMTS HSPA Networks Worldwide
20 © Nokia Siemens Networks
Technology Forecast
21 © Nokia Siemens Networks
Subscriber Forecast
22 © Nokia Siemens Networks
Data Rate Evolution
23 © Nokia Siemens Networks
•3G Rollout in India has already been delayed due to various reasons.
•Operators are taking time before committing themselves for such a Hugh investments.
•The way Indian Mobile Industry is growing, there is definitely need for a more spectrum efficient technology – 3G is the right choice for that
•Tentative timeline for initial rollout looks like to be sometime this year then 2010 will be the year when many more rollout may take place.
Future of 3G in India – The Question!!!!!
24 © Nokia Siemens Networks
Indian Wireless Market
GSM market share to increase from 73% in 2008 to 79% in 2013
25 © Nokia Siemens Networks
Indian Subscriber growth and pattern
26 © Nokia Siemens Networks
3G and BWA Subscribers in India
27 © Nokia Siemens Networks
Application Usage Pattern
28 © Nokia Siemens Networks
GSMGSM GSM WCDMA
HSCSD
GPRS
EDGE
CDMAIS-95A
CDMACDMA
IS-95B
1xRTT 1xEV-DO 1xEV-DVCDMA2000
3xRTT
2G 2.5G 3G
Multiple phases
Focus of this Workshop
The Roads to 3G
© Nokia Siemens Networks
WCDMA Network Architecture and Interfaces
30 © Nokia Siemens Networks
UMTS NW Architecture
Iu
Uu
User Equipment(UE)
IurIub
UTRAN
RNC
WCDMA BTS
WCDMA BTS
WCDMA BTS
WCDMA BTS
RNC
Core Network
(CN)
31 © Nokia Siemens Networks
Interfaces of UMTS System
CN
Circuitswitched
(cs) domain
packetswitched
(ps)domain
UTRAN
Radio Network Subsystem (RNS)
Radio Network Subsystem (RNS)
Iub
Iub
Iur
Iu-PS
Iu-CS
Uu
Uu
UE
UE
MSC/VLR
SGSN
RNC
RNC
32 © Nokia Siemens Networks
General UE Architecture
UU
UE
CU
USIM
ME
Mobile Equipment
UMTS SIM
UTRANTerminal
Equipment
33 © Nokia Siemens Networks
General UTRAN Architecture
UU IU
UE
UTRAN
IUb
IUr
Node B
Node B
Node B
Node B
RNC
RNC
Radio Network Controller
Radio Network Controller
Iu-ps
Iu-cs
IUb
CN (MSC)
CN (SGSN)
34 © Nokia Siemens Networks
Elements of UTRAN
Radio Network Controller
• Owns and controls radio resources in its domain (BSC in GSM)
• Service Access Point for all services that UTRAN provides for the CN
• Note: Service RNC (SRNC) and Drift RNC (DRNC) are subsets
Node B
• Acts as the radio base station (BTS in GSM)
• Converts the data flow between the Iub and Uu interfaces
35 © Nokia Siemens Networks
Major Interfaces in UMTS
There are four major new interfaces defined in UMTS
• Iu
– The interface between UTRAN and the CN
• Iur
– The Interface between different RNCs
• Iub
– The interface between the Node B and the RNC
• Uu
– The air interface
RNC
Node-B
RNC
UE
CN
Uu
Iu
Iub
Iur
36 © Nokia Siemens Networks
Iu - the Core Network to UTRAN Interface
There are two parts to the Iu interface
• Iu-ps connecting UTRAN to the PS Domain of the CN
• Iu-cs connecting UTRAN to the CS Domain of the CN
No radio resource signalling, travels over this interface
• The Iu interface divides the UMTS network into the radio specific UTRAN and the CN.
RNC
Node-B
RNC
UE
CN
Uu
Iu
Iub
Iur
37 © Nokia Siemens Networks
Iur - the Inter-RNC Interface
The Iur interface allows soft handovers between Node-Bs attached to different RNCs
It is an open interface to allow the use of RNCs from different manufacturers
Its functions may be summarised:
• Support of basic inter-RNC mobility
• Support of Dedicated and Common Channel Traffic
RNC
Node-B
RNC
UE
CN
Uu
Iu
Iub
Iur
38 © Nokia Siemens Networks
Iub - the RNC to Node-B Interface
The Iub is an open interface to allow the support of different manufacturers supplying RNCs and Node-Bs
Its major functions are:
• Carries dedicated and common channel traffic between the RNC and the Node-B
• Supports the control of the Node-B by the RNC
RNC
Node-B
RNC
UE
CN
Uu
Iu
Iub
Iur
39 © Nokia Siemens Networks
Uu - the Air Interface
Clearly the Uu must be standardised to allow multiple UE vendors to be supported by a network
The major functions of the Uu are to:
• Carry dedicated and common channel traffic across the air interface
• Provide signaling and control traffic to the mobile from the RNC and the Node-B
RNC
Node-B
RNC
UE
CN
Uu
Iu
Iub
Iur
© Nokia Siemens Networks
WCDMA Services
41 © Nokia Siemens Networks
UMTS QoS Classes
UMTS attempts to fulfil QoS requests from the user
Four traffic classes have been specified
• Conversational
• Streaming
• Interactive
• Background
Main distinguishing feature is delay sensitivity
43 © Nokia Siemens Networks
QoS Classes
Telephony
Videotelephony
Filedownloading
Webbrowsing
Maildownloading
Calendersynchronisation
Teleworking
Teleshopping
Streamingvideo
Streamingmusic
44 © Nokia Siemens Networks
Conversational Class
•Conversational pattern - symmetric
•Real time, Extremely delay sensitive
•Typically between peers
•Example Applications:– Voice
– Video telephony
45 © Nokia Siemens Networks
Streaming
•Highly asymmetric
•Real time, relatively low delay required
•Typically between server and client
•Example Applications– Web broadcast
– Video on demand
– Streaming multimedia
46 © Nokia Siemens Networks
Interactive
•Request response pattern
•Preserve data integrity
•Relatively delay sensitive but not real time
•Treated as non-real time packet based service
•Example applications:– Web browsing
– Location based services
– Database retrieval
47 © Nokia Siemens Networks
Background
•Destination is not expecting the data within a certain time
•Preserve data integrity
•Treated as non-real time packet based service
•Example Applications– Download of Emails
– File download
© Nokia Siemens Networks
Basic Concepts of WCDMA- Radio
49 © Nokia Siemens Networks
UMTS Air Interface Technical Aspects
51 © Nokia Siemens Networks
Access Technology Explanation
Multiple Access means “Many users share the same medium”
There are a number of different Multiple Access (MA) strategies :
• Time Division Multiple Access (TDMA)
• Frequency Division Multiple Access (FDMA)
• Code Division Multiple Access (CDMA)
52 © Nokia Siemens Networks
TDMA
freq
uen
cy
time
User 1 User 1
Timeslot Period Frame Period
Idealised TDMA (with no guard periods)
Available Frequency Band
53 © Nokia Siemens Networks
FDMA
freq
uen
cy
time
User 1
Frame Period (we may still need frames/timeslots for signaling)
Channel Bandwidth
Idealised FDMA (with no guard bands)
54 © Nokia Siemens Networks
CDMA - Direct Sequence Spread Spectrum
freq
uen
cy
time
code
Frame Period (we may still need frames/timeslots for signaling)
55 © Nokia Siemens Networks
WCDMA Technology
5 MHz
3.84 M Hz
f
5+5 MHz in FDD mode5 MHz in TDD mode
Freq
uenc
y
TimeDirect Sequence (DS) CDMA
WCDMA Carrier
WCDMAWCDMA5 MHz, 1 carrier5 MHz, 1 carrier
TDMA (GSM)TDMA (GSM)5 MHz, 25 carriers5 MHz, 25 carriers
Users share same time and frequency
56 © Nokia Siemens Networks
UMTS & GSM Radio Network Planning
GSM900/1800: 3G (W CDM A):
57 © Nokia Siemens Networks
Concepts of Spreading in WCDMA
58 © Nokia Siemens Networks
Spreading
60 © Nokia Siemens Networks
Bits, Chips and Spreading Factor
• Each user data bit is multiplied with a sequence of 'x' code bits called CHIPS.
•Data bits when spreaded with code sequence is known as chips
DataBit rate
Spreading Code
chip rate
In order to distinguish between the information-carrying bits in the
user data and the bits in the user spreading codes, we tend to use the term ‘chips’ to refer to the bits in the spreading code
61 © Nokia Siemens Networks
Bits, Chips and Spreading Factor
• Each user data bit is multiplied with a sequence of 'x' code bits called CHIPS.
•Data bits when spreaded with code sequence is known as chips
Example:
Spreading code 1 = (1, -1)
Data to spread = (1,0,1,1)
• Data after spreading = (1, -1).(1), (1,-1).(0), (1,-1).1, (1,-1).1 = (1,-1, -1,1,1-1,1,-1)
Spreading factor (SF) = Spreaded Signal BW / Unspreaded Signal BW
= The number of chips per data
• In the above example : SF= 8/4 = 2
DataBit rate
Spreading Code
chip rate
62 © Nokia Siemens Networks
Spreading and Despreading
SpreadingEach user data bit is multiplied with a sequence of 'x' code bits called CHIPS. This 'x' determines the SPREADING FACTOR!!!!
The resulting spread data is at a rate of 'x' times user data rate
DespreadingThe spread user data/chip sequence is multiplied with the same 'x' code chips to recover the original data.
Example:
Spreading code 1 = (1, -1)
Data to spread = (1,0,1,1)
• Data after spreading = (1, -1).(1), (1,-1).(0), (1,-1).1, (1,-1).1
= (1,-1, -1,1,1-1,1,-1)
• Despreading : Multiply the received signal with same spreading code
• ( 1, -1, -1, 1, 1, -1, 1, -1).(1,-1)– 1. Take first two chips = (1,-1).(1,-1) = 1+1 = 2 = +ve => 1
– 2. Take next two chips = (-1,1).(1,-1) = -1 -1 = -2 = -ve => 0
– 3. Take next two chips = (1,-1).(1,-1) = 1+1 = 2 = +ve => 1
– 4. Take next two chips = 1,-1).(1,-1) = 1+1 = 2 = +ve => 1
63 © Nokia Siemens Networks
Spreading
64 © Nokia Siemens Networks
Frequency
Pow
er
den
sity
(W
att
s/H
z)
Unspread narrowband signal Spread wideband signal
Bandwidth W (3.84 Mchip/sec)
User bit rate R
R
WdBGp Processing
gain:
Spreading & Processing Gain
• Spreading Operation helps the signal resist interference and also enables the original data to be recovered if data bits are damaged during transmission
65 © Nokia Siemens Networks
Frequency (Hz)
Voice user (R=12,2 kbit/s)
Packet data user (R=384 kbit/s)
Pow
er
den
sity
(W
/Hz)
R
Frequency (Hz)
Gp=W/R=24.98 dB
Pow
er
den
sity
(W
/Hz)
R
Gp=W/R=10 dB
• Spreading sequences have a different length• Processing gain depends on the user data rate
Example
66 © Nokia Siemens Networks
WCDMA Spreading and Scrambling Operation
In WCDMA two separate codes are used in the spreading operation
• Channelisation code (spreading code)
• Scrambling code
Data
Bit rate
Chanelization code (SF)
scrambling code
chip rate chip rate
67 © Nokia Siemens Networks
WCDMA CodesIn WCDMA two separate codes are used in the spreading operation
– Channelisation code
– Scrambling code
Scrambling code– DL: separates cells in same carrier frequency
– UL: separates users
Channelisation code– DL: separates different users within a cell
– UL: separates physical channels of one user
68 © Nokia Siemens Networks
DL Spreading and Scrambling in WCDMA
User 1 Signal
X
Channlisation code 1
X
Channelisation Code 2
X
+
X
SCRAMBLINGCODE
RF
3.84 MHzRF carrier
3.84 MHz bandwidth
CHANNELISATION codes:
User 2 Signal
Channelisation Code 3
User 3 Signal
Node B
69 © Nokia Siemens Networks
UL Spreading and Scrambling in WCDMA
User 1 Signal
X
Channlisation code 1
X
Channelisation Code 2
X
X
Scrambling Code 1
RF
CHANNELISATION codes:
User 2 Signal
Channelisation Code 3
User 3 Signal
X
X
Scrambling Code 2
Scrambling Code 3Scrambling Code 3RF
Node B
70 © Nokia Siemens Networks
DL Spreading and Multiplexing in WCDMA
User 3
User 2
User 1
BCCH
Pilot X
CODE 1
X
CODE 2
X
CODE 3
X
CODE 4
X
CODE 5
+
X
SCRAMBLINGCODE
RF
SUM
User 2
User 1
BCCH
Pilot
Radio frame = 15 time slots
Time
User 3
3.84 MHzRF carrier
3.84 MHz bandwidth
CHANNELISATION codes:
P-CPICH
P-CCPCH
DPCH1
DPCH2
DPCH3
71 © Nokia Siemens Networks
Property of the Chanalization (Spreading) Codes
Orthogonality
Two codes are said to be orthogonal when their inner product is zero.
Let: let S1 be one SF code & S2 another
• Then : S1* S2 = 0
Eg:(1, 1, 1, 1) and (1, 1, -1, -1) are orthogonal:
(1 * 1) + (1 * 1) + (1 * -1) + (1 * -1) = 0
72 © Nokia Siemens Networks
Orthogonal spreading code Tree & Generation
SF = 1 SF = 2 SF = 4
Cch,1,0 = (1)
Cch,2,0 = (1,1)
Cch,2,1 = (1,-1)
Cch,4,0 =(1,1,1,1)
Cch,4,1 = (1,1,-1,-1)
Cch,4,2 = (1,-1,1,-1)
Cch,4,3 = (1,-1,-1,1)
Top sub-element
Bottom sub-element
73 © Nokia Siemens Networks
Channelisation Code Tree
C0(0)=[1]
C2(1)=[1-1]
C2(0)=[11]
C4(0)=[1111]
C4(1)=[11-1-1]
C4(2)=[1-11-1]
C4(3)=[1-1-11]
C8(0)=[11111111]
C8(1)=[1111-1-1-1-1]
C8(2)=[11-1-111-1-1]
C8(3)=[11-1-1-1-111]
C8(0)=[1-11-11-11-1]
C8(5)=[1-11-1-11-11]
C8(6)=[1-1-111-1-11]
C8(7)=[1-1-11-111-1]
C16(0)=[............]C16(1)=[............]
C16(15)=[...........]
C16(14)=[...........]
C16(13=[...........]
C16(12)=[...........]
C16(11)=[...........]
C16(10)=[...........]
C16(9)=[............]
C16(8)=[............]
C16(7)=[............]
C16(6)=[............]
C16(5)=[............]
C16(4)=[............]
C16(3)=[............]
C16(2)=[............]
SF=1
SF=2
SF=4
SF=8
SF=16
SF=256
SF=512
...
74 © Nokia Siemens Networks
Example
Spreading code 1 = (1, -1)
Date to spread = (1,0,1,1)
• Data after spreading = (1, -1).(1), (1,-1).(0), (1,-1).1, (1,-1).1 = (1,-1, -1,1,1-1,1,-1)
Spreading code 2 = (1,1)
Date to spread = (0,0,1,1)
Data after spreading = (-1,-1, -1,-1, 1,1, 1,1 )
Combined signal = (1,-1,-1,1,1,-1,1,-1) + (-1,-1,-1,-1,1,1,1,1) = (0,-2,-2,0,2,0,2,0)
User 1 decodes it by simple vector multiplication
(0,-2, -2,0, 2,0, 2,0) . (1,-1)
1. Take first 2 bits = (0,-2).(1,-1) = (0).(1) + (-2).(-1) = 0+ 2 = 2 => +ve => 1
2. Take next 2 bits = (-2,0).(1,-1) = (-2).(1) + (0).(-1) = -2+0 = -2 => -ve => 0
3. Take next 2 bits (2,0).(1,-1) = 2.1 + 0.-1 = 2 + 0 = 2 => =+ve => 1
4. Take next 2 bits (2,0).(1,-1) = 2 => +ve => 1
That way all 4 bits are retrieved at the receiver side.
75 © Nokia Siemens Networks
Multipath and Rake Receiver
76 © Nokia Siemens Networks
Multipath Propagation
Scrambling code
C1
Scrambling code
C2
C 1+
3
C1+2
C1+1
C2
77 © Nokia Siemens Networks
Operation in Multipath Environment
Radio propagation is characterized by multipath propagation which may result into attenuation of signal energy
79 © Nokia Siemens Networks
Operation in Multipath environment/Rake reception
Rake ReceptionWCDMA requires some countermeasures against Fast fading!!!!The solution is RAKE RECEIVER!!!!!
So what is a RAKE RECEIVER????
Fading????!!!
Fingers??!!
Spreading/Despreading???!!!
80 © Nokia Siemens Networks
Rake Receiver
•A rake receiver is a radio receiver designed to counter the effects of multipath fading. It does this by using several "sub-receivers" called fingers, each assigned to a different multipath component
Multipath components are delayed copies of the original transmitted wave traveling through a different path, each with a different magnitude and time-
of-arrival at the receiver
Since each component contains the original information, if the magnitude and time-of-arrival (phase) of each component is computed at the receiver (through a process called channel estimation), then all the components can
be added coherently to improve the information reliability. This could very well result in higher signal-to-noise ratio (or Eb/N0) in a multipath environment
81 © Nokia Siemens Networks
RAKE Receiver
82 © Nokia Siemens Networks
RAKE RECEPTION
Operating Principle of Rake Receiver Assign a RAKE finger to each time delay position where significant energy arrives. Within each correlation receiver track the fast changing phase and amplitude
Transmitted symbol Received signal at each time delay Modified with channel estimate Combined Symbol
finger1
finger2
finger3
83 © Nokia Siemens Networks
UMTS Bearers
AMR 12.2AMR 12.2
Transparent CS data 64Transparent CS data 64
Non-transparent CS data 14.4, 57.6Non-transparent CS data 14.4, 57.6
NRT PS data 8, 16, 32, 64, 128, 256, 384 (UL/DL) (CELL_DCH)NRT PS data 8, 16, 32, 64, 128, 256, 384 (UL/DL) (CELL_DCH)
NRT PS data 16 (UL), 32 (DL) (CELL_FACH)NRT PS data 16 (UL), 32 (DL) (CELL_FACH)
Streaming PS data 8, 16, 32, 64, 128, 256 (DL)Streaming PS data 8, 16, 32, 64, 128, 256 (DL)
Lower AMR speech codecs: 7.95, 5.90, 4.75 , 12.65, 8.85, 6.6Lower AMR speech codecs: 7.95, 5.90, 4.75 , 12.65, 8.85, 6.6
84 © Nokia Siemens Networks
Concepts of RSCP and Ec/No
Two Important Terms
• RSCP
• Ec/No, Ec/Io
85 © Nokia Siemens Networks
Scrambling Codes & CPICH
The Common Pilot Channel (CPICH) is broadcast from every cell
It carries no information and can be thought of as a “beacon” constantly transmitting the Scrambling Code of the cellWCDMA cells are identified by their SC.
Its like a BCCH in GSM
It is this “beacon” that is used by the phone for its cell measurements for network acquisition and handover purposes (Ec, Ec/Io).
CPICH
86 © Nokia Siemens Networks
Total Received Power Io
In a WCDMA network the User Equipment (UE) receives signals from many cells
Io* = The sum total of all of these signals (dBm)
*Note: Sometimes Io is referred to as No, RSSI
Io
87 © Nokia Siemens Networks
Received Power of CPICH : RSCP
RSCP
Using the properties of SCs the UE is able to extract the respective CPICH levels from the sites received
RSCP = The Received Power of a Particular CPICH (dBm)
Ec = Energy per Chip
RSCP 1 RSCP 2
88 © Nokia Siemens Networks
CPICH Quality (Ec/Io)
IoRSCP
From the previous two measures we can calculate a signal quality for each CPICH (SC) received
Ec/Io = (Energy per chip / Noise spectral density) = RSCP/RSSI
*Note: Sometimes Ec/Io is referred to as Ec/No
89 © Nokia Siemens Networks
Relation between Ec/Io and Eb/No
90 © Nokia Siemens Networks
Handover Types
Intra-Frequency HandoversSofter HandoverSoft HandoverHard Handover
Inter-Frequency Handover• Can be intra-BS, intra-RNC, inter-RNC
• Decision algorithm located in RNC
Inter-RAT Handover • Handovers between GSM and WCDMA
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Handovers - Softer Handover
• Handover between sectors of the same Node B (handled by BTS)• No extra transmissions across Iub interface• Maximum Ratio Combining (MRC) is occurring in both the UL and DL
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Handovers - Soft Handover
• MS simultaneously connected to multiple cells (from different Node Bs)• Extra transmission across Iub, more channel cards are needed (compared
to non-SHO)• Mobile Evaluated Handover (MEHO)• DL/UE: MRC & UL/RNC: Frame selection combining
93 © Nokia Siemens Networks
Handovers - Inter frequency HO
Inter frequency handover occurs between two WCDMA carriersWill be used once operator deploys its second carrier
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Handovers - Inter system HO
Inter system handover occurs between 3G and 2G sitesAs with all handovers, accurate adjacencies will be required
3G 2G
95 © Nokia Siemens Networks
Handover types
Soft Handover
4
Hard/Inter-Frequency Handover
Inter-System Handover
Node B
Frequencyf1
Frequencyf1
Frequencyf1
Frequencyf2
UMTS GSM900/1800
Frequencyf1
Frequencyf1
RNC RNC
Iur
Iub Iub
Node B
Node B Node B
Node BNode B
Softer Handover
Sector 1f1
Sector 2f1
Sector 3f1
Sector 1
Sector 3
Node B
Node B BTS
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Air Interface Channels
98 © Nokia Siemens Networks
WCDMA Frame
• Radio frame: A radio frame is a processing duration which consists of 15 slots. The length of a radio frame corresponds to 38400 chips.
• Slot: A slot is a duration which consists of fields containing bits. The length of a slot corresponds to 2560 chips
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
10ms
99 © Nokia Siemens Networks
Air Interface Access Stratum
L3
L2
L1
Radio Resource
Control RRC
Radio Link Control RLC
Medium Access
Control MAC
Physical Layer
Control Plane Signalling
User Plane Information
Logical
Channels
Transport Channels
Physical Channels
100 © Nokia Siemens Networks
UMTS Channel Types and Functions
There are three types of channel across the air interface and access stratum that we are interested in:
• Logical Channels
– Between the RLC and MAC layers
– What kind of data is transmitted
• Transport Channels
– Between the MAC and Physical layers
– How data is transmitted – characteristics of data transmission
• Physical Channels
– Between Physical Layers at the Node-B and UE
– Actual transmission/reception of data
101 © Nokia Siemens Networks
Logical Channelscontent is organised in separate channels, e.g.
System information, paging, user data, link management
Transport Channelslogical channel information is organised on transport channel
resources before being physically transmitted
Physical Channels(UARFCN, spreading code)
FramesIub interface
Radio Interface Channel Organisation
102 © Nokia Siemens Networks
P-CCPCH
PCH
BCH
DCCH
CCCH
PCCH
BCCH
DCH
P-CPICH
S-SCH
P-SCHFACH
HS-DSCH
AICH
HS-PDSCH
DPDCH
S-CCPCH
DTCH
PICH
LogicalChannels
TransportChannels
PhysicalChannels
DPCCH
Channel Mapping DL (Network Point of View)
HS-SCCH
103 © Nokia Siemens Networks
DCCH
DCH DPDCHDTCH
LogicalChannels
TransportChannels
PhysicalChannels
RACHCCCH PRACH
DPCCH
Channel Mapping UL (Network Point of View)
HS-DPCCH
104 © Nokia Siemens Networks
Logical Control Channels
The Broadcast Control Channel (BCCH) is a downlink channel for broadcasting system control information
The Paging Control Channel (PCH) is a downlink channel that transfers paging information
The Dedicated Control Channel (DCCH) is a point-to-point bi-directional channel transmitting control information between a specific UE and the UTRAN
The Common Control Channel (CCCH) is a bi-directional channel transmitting control information between UEs and the UTRAN
P-CCPCH
PCH
BCH
DCCH
CCCH
PCCH
BCCH
DCH
P-CPICH
S-SCHP-SCH
FACH
HS-DSCH
AICH
HS-PDSCH
DPDCH
S-CCPCH
DTCH
PICH
DPCCH
HS-SCCH
105 © Nokia Siemens Networks
Logical Traffic Channels
The Dedicated Traffic Channel (DCH) is a point-to-point channel dedicated to a single UE for the transfer of user information
P-CCPCH
PCH
BCH
DCCH
CCCH
PCCH
BCCH
DCH
P-CPICH
S-SCH
P-SCHFACH
HS-DSCH
AICH
HS-PDSCH
DPDCH
S-CCPCH
DTCH
PICH
DPCCH
HS-SCCH
106 © Nokia Siemens Networks
Common Transport Channels
The Broadcast Channel (BCH) is a cell-wide channel that is used to broadcast system and cell-specific information. The BCH is always transmitted over the entire cell with a low fixed bit rate.
The Paging Channel (PCH) is a cell-wide channel that is used to carry control information to a UE when the system does not know the location cell of the UE
The Forward Access Channel (FACH) is a downlink channel that is used to carry control information to a UE when the system knows the location cell of the UE. May also carry short user packets.
The Random Access Channel (RACH) is an uplink control channel from the UE. May also carry short user packets
P-CCPCH
PCH
BCH
DCCH
CCCH
PCCH
BCCH
DCH
P-CPICH
S-SCHP-SCH
FACH
HS-DSCH
AICH
HS-PDSCH
DPDCH
S-CCPCH
DTCH
PICH
DPCCH
HS-SCCH
107 © Nokia Siemens Networks
Dedicated Transport Channels
The Dedicated Channel (DCH) is a channel dedicated to one UE used in uplink or downlink.
P-CCPCH
PCH
BCH
DCCH
CCCH
PCCH
BCCH
DCH
P-CPICH
S-SCH
P-SCHFACH
HS-DSCH
AICH
HS-PDSCH
DPDCH
S-CCPCH
DTCH
PICH
DPCCH
HS-SCCH
108 © Nokia Siemens Networks
The Primary-Common Control Physical Channels (P-CCPCH) is used to carry broadcast information across the cell
The Secondary-Common Control Physical Channels (S-CCPCH) is used to carry paging and forward access information across the cell
The Primary-Synchronisation Channel (P-SCH) is used during cell search to provide timing information
The Secondary-Synchronisation Channel (S-SCH) is used during cell search to provide information about the primary scrambling codes in use in the cell
The Common Pilot Channel (CPICH) is used to provide the phase reference for downlink channels
The Acquisition Indicator Channel (AICH) is used to acknowledge random access requests
Common Physical Channels for UMTS
P-CCPCH
PCH
BCH
DCCH
CCCH
PCCH
BCCH
DCH
P-CPICH
S-SCH
P-SCHFACH
HS-DSCH
AICH
HS-PDSCH
DPDCH
S-CCPCH
DTCH
PICH
DPCCH
HS-SCCH
109 © Nokia Siemens Networks
The Paging Indicator Channel (PICH) is used to enable discontinuous reception of the S-CPCCH
The Physical Random Access Channel (PRACH) is a contention based channel used for random access and to transmit small packets of information
The Physical Common Packet Channel (PCPCH) is an extension to the RACH used to carry larger packets of information on the uplink
The Access Preamble Acquisition Indicator Channel (AP-AICH) is used to indicate the reception of a preamble signature for Random Access
Common Physical Channels for UMTS
P-CCPCH
PCH
BCH
DCCH
CCCH
PCCH
BCCH
DCH
P-CPICH
S-SCH
P-SCHFACH
HS-DSCH
AICH
HS-PDSCH
DPDCH
S-CCPCH
DTCH
PICH
DPCCH
HS-SCCH
110 © Nokia Siemens Networks
Dedicated Physical Channels for UMTS
The Dedicated Physical Data Channel (DPDCH) is used to carry user information
The Dedicated Physical Control Channel (DPCCH) is used to carry dedicated control information regarding its associated DCHs
P-CCPCH
PCH
BCH
DCCH
CCCH
PCCH
BCCH
DCH
P-CPICH
S-SCH
P-SCHFACH
HS-DSCH
AICH
HS-PDSCH
DPDCH
S-CCPCH
DTCH
PICH
DPCCH
HS-SCCH
111 © Nokia Siemens Networks
DL Common Control Channel
Most common channel have fixed configuration and power
• CPICH
• P-CCPCH
• P-SCH, S-SCH
• AICHSetting the DL Common Control Channel Power is a trade off between:
• cell coverage: all the channels must be decoded at the cell edge
• cell capacity: the common channel power consume resources from the traffic channels
112 © Nokia Siemens Networks
Pilot Channel Power Setting
By default the CPICH consumes 2 W of the Node B power (20 W PA)
• For 40 W PA default is 4 W (10 %)CPICH power is used to derive the power requirements of the other Common Control Physical Channels (CCPCH)
The CPICH should be tuned on a per carrier per area basis as part of wide area parameter tuning following the radio network planning activity
Adjust CPICH transmit Power
Identify Cells with poor coverage
Identify Cells with excessive coverage
Evaluate Ec/Io and RSCP
performance
113 © Nokia Siemens Networks
DL Common Control Channel
DL Common Channels does not have a power control.
The power of the common physical channels are set relative to the CPICH
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Effect of CPICH Power modification
CPICH Transmit Power
Increased soft handover overhead
Less Power Available for traffic
CPICH coverage holes
Unreliable scrambling code detection
Unreliable channel estimation
Early cell reselection /handover
Increased Eb/No requirement
Reduced system capacity
Reduced system capacity
Reduced system coverage
Slow initial synchonisation
Non-ideal traffic distribution
Late cell reselection /handover
Non-ideal traffic distribution
CPICH Transmit Power
Increased soft handover overhead
Too much
power
Too little power
Less Power Available for traffic
CPICH coverage holes
Unreliable scrambling code detection
Unreliable channel estimation
Early cell reselection /handout too early
Increased Eb/No requirement
Reduced system capacity
Reduced system capacity
Reduced system coverage
Slow initial synchonisation
Non-ideal traffic distribution
Late cell reselection /handout too late
Non-ideal traffic distribution