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1
IMT-2000• IMT-2000 stands for
IMT: International Mobile Communications2000: the frequency range of 2000 MHz and the year 2000
• In total, 17 proposals for different IMT-2000 standards were submitted by regional SDOs to ITU in 1998. 11 proposals for terrestrial systems and 6 for mobile satellite systems (MSSs).
• All 3G standards have been developed by regional standard developing organizations (SDOs).
• Evaluation of the proposals was completed in 1998, and negotiations to build a consensus among different views were completed in mid 1999. All 17 proposals have been accepted by ITU as IMT-2000 standards. The specification for the Radio Transmission Technology (RTT) was released at the end of 1999.
2
IMT-2000
• The (IMT-2000), consists of 3 operating modes based on Code Division Multiple Access (CDMA) technology.
• 3G CDMA modes are most commonly known as:– CDMA2000,– WCDMA (called UMTS) and– TD-SCDMA
(Time Division-Synchronous Code Division Multiple Access)
3
High-Speed Packet Data Services
• 2 Mbps in fixed or in-building environments (very short distances, in the order of metres)
• 384 kbps in pedestrian or urban environments
• 144 kbps in wide area mobile environments
• Variable data rates in large geographic area systems (satellite)
4
5
Network Elements from UMTS
UMTS differs from GSM Phase 2+ (GSM +GPRS) mostly in the new principles for the air interface transmission
WCDMA instead of TDMA/FDMA
Therefore a new RAN (Radio Access Network) called:
UTRAN (UMTS Terrestrial Radio Access Network) must be introduced with UMTS
Only minor modifications are needed in the CN (Core Network) to accommodate the change
6
UTRA: UMTS Terrestrial Radio Access
The most significant change in REL. ´99 was the “UTRAN”, a W-CDMA radio interface for land-based communications.
UTRAN supports time (TDD) and frequency division duplex (FDD).
The TDD mode is optimized for public micro and pico cells and unlicensed cordless applications.
The FDD mode is optimized for wide-area coverage, i.e. public macro and micro cells.
Both modes offer flexible and dynamic data rates up to 2 Mbps.
7
UMTS architecture
UTRAN (UTRA NETWORK)
• Radio Network Subsystem (RNS)
UE (User Equipment)
CN (Core Network)
Uu Iu
CNUTRANUE
8
UTRANTwo new network elements are introduced in UTRAN
• RNC
• Node B
UTRAN is subdivided into individual radio network systems (RNSs), where each RNS is controlled by an RNC.
The RNC is connected to a set of Node B elements, each of which can serve one or several cells.
UTRAN architecture
UTRAN comprises several RNSs
Node B can support FDD or TDD or both
RNC is responsible for handover decisions requiring signaling to the UE
Cell offers FDD or TDD
RNC: Radio Network Controller
RNS: Radio Network SubsystemNode B
Node B
RNC
Iub
Node B
UE1
RNS
CN
Node B
Node B
RNC
Iub
Node B
RNS
Iur
Node B
UE2
UE3
Iu
10
UTRAN functions
• Admission control• Congestion control• Radio channel encryption• Handover• Radio network configuration• Channel quality measurements• Radio resource control• Data transmission over the radio interface• Outer loop power control (FDD and TDD)• Channel coding
Core network
BTS
Node B
BSC
Abis
BTS
BSS
MSC
Node B
Node B
RNC
Iub
Node BRNS
Node BSGSN GGSN
GMSC
HLR
VLR
IuPS
IuCS
Iu
CN
EIR
GnGi
PSTN
AuC
GR
The Core Network (CN) and the Interface Iu, are separated into two logical domains:
Circuit Switched Domain (CSD)• Circuit switched service incl. signaling• Resource reservation at connection setup• GSM components (MSC, GMSC, VLR)• IuCS
Packet Switched Domain (PSD)• GPRS components (SGSN, GGSN)• IuPS
Access method CDMA
•CDMA (Code Division Multiple Access)– all terminals send on the same frequency
probably at the same time and can use the whole bandwidth of the transmission channel
– each sender has a unique random number, the sender XORs the signal with this pseudo random number
– the receiver can “tune” into this signal if it knows the pseudo random number, tuning is done via a correlation function
Spreading and scrambling of user data
• Constant chip rate of 3.84 Mchip/s
• Different user data rates supported via different spreading factors– higher data rate: less chips per bit and vice versa
• User separation via unique, quasi orthogonal scrambling codes– users are not separated via orthogonal spreading codes– much simpler management of codes: each mobile can use
the same orthogonal spreading codes
data1 data2 data3
scramblingcode1
spr.code3
spr.code2
spr.code1
data4 data5
scramblingcode2
spr.code4
spr.code1
sender1 sender2
Length iR
1
LengthcR
1
i
c
c
i
R
R
R
R 1
1
SPREADING FACTOR
DS-CDMA= Direct Sequence Code Division Multiple Access
3.84 Mchip/s
• Sender A
– sends Ad = 1, key Ak = 010011 (assign: „0“= -1, „1“= +1)
– sending signal As = Ad * Ak = (-1, +1, -1, -1, +1, +1)
• Sender B
– sends Bd = 0, key Bk = 110101 (assign: „0“= -1, „1“= +1)
– sending signal Bs = Bd * Bk = (-1, -1, +1, -1, +1, -1)
• Both signals superimpose in space – interference neglected (noise etc.)
– As + Bs = (-2, 0, 0, -2, +2, 0)
• Receiver wants to receive signal from sender A
– apply key Ak bitwise (inner product)
Ae = (-2, 0, 0, -2, +2, 0) Ak
(-2, 0, 0, -2, +2, 0) (-1, +1, -1, -1, +1, +1)= 2 + 0 + 0 + 2 + 2 + 0 = 6•result greater than 0, therefore, original bit was „1“
– receiving BBe = (-2, 0, 0, -2, 2, 0) Bk
( -2, 0, 0,- 2,- 2, 0) (1, 1, -1, +1, -1, +1) = -6, i.e. „0“
CDMA in theory
CDMA on signal level Idata A
key A
signal A
data key
key sequence A
Real systems use much longer keys resulting in a larger distance between single code words in code space.
1 0 1
10 0 1 0 0 1 0 0 0 1 0 1 1 0 0 1 101 1 0 1 1 1 0 0 0 1 0 0 0 1 1 0 0
Ad
Ak
As
Here the binary ”0” is assigned a positive value,The binary ”1” a negative value!
CDMA on signal level IIsignal A
data B
key B
keysequence B
signal B
As + Bs
data key
1 0 0
00 0 1 1 0 1 0 1 0 0 0 0 1 0 1 1 111 1 0 0 1 1 0 1 0 0 0 0 1 0 1 1 1
Bd
Bk
Bs
As-1
+1
+1
-1
-2
0
+2
CDMA on signal level III
Ak
(As + Bs) * Ak
integratoroutput
comparatoroutput
As + Bs
data A
1 0 1
1 0 1 Ad
-2
0
+2
-2
0
+2
1
-1
CDMA on signal level IV
integratoroutput
comparatoroutput
Bk
(As + Bs) * Bk
As + Bs
data B
1 0 0
1 0 0 Bd
comparatoroutput
CDMA on signal level V
wrong key K
integratoroutput
(As + Bs) * K
As + Bs
(0) (0) ?
-2
0
+2
-2
+2
0
OSVF coding
1
1,1
1,-1
1,1,1,1
1,1,-1,-1
X
X,X
X,-X 1,-1,1,-1
1,-1,-1,1
1,-1,-1,1,1,-1,-1,1
1,-1,-1,1,-1,1,1,-1
1,-1,1,-1,1,-1,1,-1
1,-1,1,-1,-1,1,-1,1
1,1,-1,-1,1,1,-1,-1
1,1,-1,-1,-1,-1,1,1
1,1,1,1,1,1,1,1
1,1,1,1,-1,-1,-1,-1
SF=1 SF=2 SF=4 SF=8
SF=n SF=2n
...
...
...
...
Ortogonal Variable Spreading Factor Codes
Recursive rule
Support of mobility: macro diversity
• Multicasting of data via several physical channels– Enables soft handover– FDD mode only
• Uplink– simultaneous reception of
UE data at several Node Bs
• Downlink– Simultaneous transmission
of data via different cellsCNNode B RNC
Node BUE
despreading
despreading
Power control
Transmit Power Control is essential
MS
MS
MS
MS
Near – far problem
Node B
Node B
Transmit Power Control
Minimize the Tx power
Increase the system capacity
More secure detection
27
A case of 3 cell repetitions
Frequency Allocation
f1
f1
f1 f1
f1
f1
f1
f1
f1
f1
f1
f1
f1
f1
f1
f1
f1
f1
f1
f1
f1
f1
f1
f2 f2
f3
f1
f1
f3
f2
f1
f3
f1
f3
f2
f2
f1
f3
f3
f2
f3
f2
FDMA / TDMA CDMA
Same frequency in all cells.
UMTS protocol stacks (user plane)
apps. &protocols
MAC
radio
MAC
radio
RLC SAR
UuIuCSUE UTRAN 3G
MSC
RLC
AAL2
ATM
AAL2
ATM
SAR
apps. &protocols
MAC
radio
MAC
radio
PDCP GTP
Uu IuPSUE UTRAN 3GSGSN
RLC
AAL5
ATM
AAL5
ATM
UDP/IP
PDCP
RLC UDP/IP UDP/IP
Gn
GTP GTP
L2
L1
UDP/IP
L2
L1
GTP
3GGGSN
IP, PPP,…
IP, PPP,…
IP tunnel
Circuitswitched
Packetswitched
29
EDGEEnhanced Data rates for GSM Evolution
• ECSD - Enhanced CSD (Circuit Switched Data)
• EGPRS - Enhanced GPRS
• For higher data rates
• New coding and modulation schemes
• The base stations need to be up dated
• EGPRS up to 384 kbps (48 kbps per time slot)
• ECSD 28.8 kbps
30
Modulation
31
The Beauty ContestTen companies asked for one out of four licences
Licences were given to
• Vodaphone• Tele2• Hi3G• Orange
The incumbent, Telia, was not given a licence!!!
32
UMTS in SwedenThe licensees have to cover 8 860 000
inhabitants.Two joint ventures:
Svenska UMTS nät - Tele2 and TeliaTelia and Tele2 have established a joint venture, Svenska UMTS nät, with a common 3G network.
3GIS – Telenor and 3*To meet the regulatory requirements, Telenor and 3 has build individualnetworks, and each has to cover 30% of the population. Telenor and 3 have established a joint venture, 3G Infrastructure Services(3GIS) with a common shared network. This network coversapproximately 70% of the population.
Björkdahl & Bohlin
33
Network coverage
Theoretically it is possible to cover 8 860 000 inhabitants by covering 20 400 km² of Sweden’s surface area. (Swedish total area is 411 000 km².) Theoretical level corresponds to a coverage of 5% of the Swedish area.
In practice, it seems reasonable that the operators will aim for a total coverage of around 170 000 km². This corresponds to a coverage of 41% of the Swedish surface area.
The operators will be able to cover all urban areas and 84% of the inhabitants by covering around 11 000 km². This corresponds to a coverage of 2.7% of the Swedish surface area.
34
Investment for an average operatorComparing
Germany, United Kingdom and Sweden
The table shows the average 3G investment per capita per year, includingapplicable license fees, in Sweden, Germany and the UK for an average operator in each country, for the entire license duration.
1 USD = 8 SEK
3.8 USD
6.2 USD
7.5 USD
35
Summary of main findings
•The average 3G network investment per operator is estimated to be SEK 6.1 billion.
•The total 3G network investment in Sweden is estimated to be SEK 24 billion.
•If the Swedish joint ventures co-operate in rural areas the total 3G network investment is estimated to be SEK 19 billion.
36
End of Chapter