Content and rem..
-
Upload
jada-chandler -
Category
Documents
-
view
21 -
download
0
description
Transcript of Content and rem..
TCS 316High Speed Information
Networks
UMTS Handover
byNasir Faruk
Email: [email protected] +234 8032428141
Week 13May, 2014
1/6019/04/23 11:35 PM
Content and rem..
• Weeks 13• Cell Search
procedure• (Skipped)• Handover
• Softer• Soft• Hard
• Sectorisation (Briefly taught last semester)
• Weeks 14 ( To be skip. You met it in industry when lucky hahaha)
• IP• IP Mobility• Mobile IP• VoIP
219/04/23 11:35 PM
Air Interface Modes
Figure 2
wray castle browser
Internet Search
http:/www.wraycastle.co.uk
XXXXXXX XXX
XXXXX XXXX
XXXX XXX XX
UMTSCore
Network
wray castle browser
Internet Search
http:/www.wraycastle.co.uk
XXXXXXX XXX
XXXXX XXXX
XXXX XXX XX
UMTS Terrestrial RadioAccess network (UTRAN)
User Equipment (UE)FDD Mode
User Equipment (UE)TDD Mode
CDMA
Frequency Division Duplex Mode 1Direct Sequence Mode
Time Division Duplex Mode 1TD-CDMA
19/04/23 11:35 PM 3
Handover Types• Within UTRA FDD – Intra-Mode Handover– Soft– Softer– Hard (intra- or inter-frequency)
• Inter Mode Handover– Handover to UTRA TDD – not implemented yet!
• Inter-system Handover– In R99 means only to GSM handover– In R8 & LTE (E-UTRA or E-UTRAN) means
handover to and from LTE (Long Term Evolution).
419/04/23 11:35 PM
Effect on Capacity with Contiguous Coverage
5Figure 9
Cell A in isolation10 channels
Interference
Cell B in isolation10 channels
Capacity of Cells A and Bis less than 20 because
of increased interference
Cell A Cell B
19/04/23 11:35 PM
Cell Capacity
Figure 10
Total Cell Capacity = 100 kbit/s
Total Cell Capacity = 100 kbit/s
10 users using10 kbit/s channel
2 users using50 kbit/s channel
619/04/23 11:35 PM
Power Control at Cell Boundaries
Figure 29
wray castle browser
Internet Search
http:/www.wraycastle.co.uk
XXXXXXX XXX
XXXXX XXXX
XXXX XXX XX
wray castle browser
Internet Search
http:/www.wraycastle.co.uk
XXXXXXX XXX
XXXXX XXXX
XXXX XXX XX
Power Control
Increase ininterference here
Power Controlinstructs mobileto turn power up
Node B1
Node B2
719/04/23 11:35 PM
Necessity for Soft/Softer Handover
• Essentially to avoid interference• Mobile could penetrate far into
adjacent cell without being power controlled by that cell
• This could be overcome by the use of very fast and frequent hard handovers
• Not efficient as too much signalling involved.
819/04/23 11:35 PM
Soft Handover
Figure 30
Node B1
Node B2
wray castle browser
Internet Search
http:/www.wraycastle.co.uk
XXXXXXX XXX
XXXXX XXXXXXXX XXX XX
Power Control
Power Control B
9
Soft Handover – make before break19/04/23 11:35 PM
WCDMA Soft Handover• Active set - the cells participating
in the soft handover• Normally just 2 cells–Neighbour or monitored set
• Cells that the UE continuously measures
• Pilot Ec/No not strong enough to be added to the active set
1019/04/23 11:35 PM
UE Measurements
Figure 21
wray castle browser
Internet Search
http:/www.wraycastle.co.uk
XXXXXXX XXX
XXXXX XXXX
XXXX XXX XX
Node B Micro
GSMBTS
Intra-frequency
Node B
Node B
Intra-frequencyDownlinkQuality
UE
RLCBuffer
UplinkTrafficVolume Internal TX power
RSSI
Local Measurement
Inter-frequency
Inter-system
19/04/23 11:35 PM 11
Ec/No Measurement from CPICH
• UTRA FDD intra-mode handover relies on the Ec/No measurement performed from the CPICH.
• Quantities defined that can be measured by the terminal from the CPICH are as follows:
• Received Signal Code Power (RSCP) – received power on one code after despreading defined on the pilot symbols;
• Received Signal Strength Indicator (RSSI) – wideband received power within the channel bandwidth;
• Ec/No = RSCP/RSSI, i.e. RSCP divided by the total power in the channel bandwidth.
1219/04/23 11:35 PM
WCDMA Handover Algorithm
• If a neighbour cell pilot channel signal remains better than the current best cell’s pilot minus a hysteresis value for a timeout period the neighbour cell may be added to the active set.
• If an active cell signal is worse than that of the current best cell minus a different hysteresis value for a short period it may be removed from the active set.
• If a neighbour cell signal is better than the current worst active cell plus a third different hysteresis value for the timeout period it may replace that worst active cell.
1319/04/23 11:35 PM
Soft Handover Region
Figure 31
A B
Soft handover region
Start End
wray castle browser
Internet Search
http:/www.wraycastle.co.uk
XXXXXXX XXX
XXXXX XXXXXXXX XXX XX
Two-Cell Case
1419/04/23 11:35 PM
Soft Handover Region
Figure 31 (continued)
Three-Cell Case
A C
B
Three-wayhandoverRequired
here
1519/04/23 11:35 PM
Example of a Soft Handover
Full specification is in 3GPP TR 25.922 V6.0.1 (2004-04)
3.Time
1. 2.
Cell C
Cell B
Cell A
Quality
Timer
MacroAdd
Threshold
MacroReplacement
Threshold
Timer
MacroRemove
Threshold
Timer
Timer
1619/04/23 11:35 PM
Soft vs Softer Handover
17
Softer Handover – also make before break19/04/23 11:35 PM
Softer Handover• Between two cells or sectors supported by the
same Node B• UE transmits & receives from both cells
simultaneously:– UE combines downlink information– Node B combines uplink information
• Only one power control loop• Both soft & softer handover may occur
simultaneously• Soft/softer handover at the UE & softer at the
Node B– Similar to multipath reception– Two separate downlink codes– RAKE fingers need to generate two codes
1819/04/23 11:35 PM
Soft Handover at the RNC
• Uplink data routed to RNC for combining
• Better frame selected– After each interleaving period 10-80 ms– Outer loop power control frame
reliability indicator utilised.
1919/04/23 11:35 PM
Serving & Drift RNC
2019/04/23 11:35 PM
Serving & Drift RNC
2119/04/23 11:35 PM
Serving & Drift RNC
2219/04/23 11:35 PM
Macro and Micro Diversity
Figure 36
RNC
wray castle browser
Internet Search
http:/www.wraycastle.co.uk
XXXXXXX XXX
XXXXX XXXX
XXXX XXX XX
UE
Macro Diversity Combiningat RNC for Soft Handover
Node B
Node B
Micro DiversityCombining at
Node B forSofter Handover
Cell B
Cell A SoftHandover
SofterHandover
19/04/23 11:35 PM 23
UMTS Hard Handover
• Between two cells using different carrier frequencies
• Between cells whose Nodes B are• connected to different RNCs without
the Iur interface• To and from GSM
2419/04/23 11:35 PM
Handover and External Reselection Related Procedures
Figure 19
RNC BSC
UMTSCore Network
GSMCore Network
Node Bmicro
Node Bmacro
Node Bmacro BTS
Hard Handoverwithin UTRAN
Soft Handoverwithin UTRAN
Hard Handoveroutside UTRAN
Reselectionoutside UTRAN
2519/04/23 11:35 PM
UMTS Handover Types - Summary
Figure 33
A = intra-frequencyB = inter-frequencyC = inter-system
wray castle browser
Internet Search
http:/www.wraycastle.co.uk
XXXXXXX XXX
XXXXX XXXXXXXX XXX XX
GSM
UMTSMacro
UMTSMacro
UMTSMicro
UE
HardC
HardB
SoftA
26
Hard Handover – break before make
19/04/23 11:35 PM