Transcript Investigation of the Advantages of TD-SCDMA Compared to WCDMA

Investigation of the Advantages of
TDSCDMA compared to WCDMA
Thesis Presentation
Author:
Wang Ying
Supervisor:
Prof. Sven-Gustav Häggman
Instructor:
M.Sc. Mikko Nieminen
7 Nov 2006
Agenda

Background

Objectives

Methodology

TDSCDMA physical layer structure

Key technologies used in TDSCDMA

Conclusion

Future study

Background
 The developing of GSM system started from early 1980’s
 February 1999 Nokia Oyj completed the first WCDMA call through the public
switched telephone network in the world.
 There are now about 2.9 million WCDMA subscribers. Most of these are in
Europe and Japan.
 TDSCDMA (Time Division Synchronous Code Division Multiple Access)
developed by the China Academy of Telecommunications Technology (CATT),
in cooperation with Siemens.
Why indeed TDSCDMA encourages Chinese government
spent over 10 years' hard work?

Objectives
 To investigate the advantages for using TDSCDMA system
compared to using WCDMA system

Methodology
 Literature research
 Discussion with experts
Network structure
Core Network
CN
Iu
Radio Access Network
RAN
Uu
User Equipment
UE
TDSCDMA physical layer structure 1/5

Physical layer interfaces with upper layers
Layer 3
Radio Resource Control
(RRC)
SAP
Medium Access Control (MAC)
Layer 2
CPHY primitives
Layer 1
Physical Layer (PHY)
PHY primitives
TDSCDMA physical layer structure 2/5
Physical
channel structure
Superframe (720ms)
Radio Frame (10ms)
Frame #0
Frame #1
Subframe (5ms)
Subframe #0
Subframe #1
Frame #71
TDSCDMA physical layer structure 3/5
Subframe
structure
Subframe 5ms (6400chip)
Switching Point
Ts0
DwPTS
(96chips)
(
Ts1
GP
(96chips)
Ts2
UpPTS
Ts3
Ts4
Ts5
Ts6
Switching Point
(160chips)
864  7  96  96  160  6400chips ; 6400chips  5ms  1.28Mchip / s
)
TDSCDMA physical layer structure 4/5

Tsn (n from 0 to 6): the normal time slot, 864 chips duration;

DwPTS: downlink pilot time slot, 96 chips duration;

UpPTS: uplink pilot time slot, 160 chips duration;

GP: main guard period for TDD operation, 96 chips duration;

Switching Point: between the downlink time slots and uplink time slots
(vice versa )
TDSCDMA physical layer structure 5/5
Normal
TS structure
675 µs
Data symbols
352 chips
DwPTS
Midamble
144 chips
Data symbols
352 chips
UpPTS
structure
Guard period
16 chips
structure
75 µs
Guard period
32 chips
125 µs
SYNC
64 chips
SYNC1
128 chips
Guard period
32 chips
Key technologies used in TDSCDMA 1/3
Combined
TDD, TDMA and CDMA operation
Depending on the
Max. used
spreading factor
• TDD: Separate Uplink and Downlink
• TDMA: Separate different users
• CDMA: Separate different users
Key technologies used in TDSCDMA 2/3
Smart
antenna
• Rx (Uplink): find the best
Eb I 0
• Tx (Downlink): beamforming can
greatly reduce the interference to
Antenna Array
other co-channel UEs also can save
output power
Feed Cables
TRx
1
TRx
2
TRx
3
...
...
Base Band Processor
...
...
TRx
M
Conclusion

1.6 MHz unpaired frequency band – efficient spectrum usage

TDD, TDMA and CDMA combined operation – better supporting
data services

Using smart antenna – efficient suppressing interference

No cell breathing – easier network planning
Future Study

Study TD-SCDMA network performance

Study the disadvantage in TD-SCDMA system
Thank You!
Appendix
Different Radio Modes with Harmonized Parameter Sets
FDD component
Multiplex
technology
TDD component
W-CDMA
TD-SCDMA
TD-CDMA
2*5 MHz paired
1*1.6 MHz unpaired
1*5 MHz unpaired
1
1 or 3
1
Hard, Soft, Softer
Hard
Hard
QPSK
QPSK and 8-PSK
QPSK
RAKE
Joint Detection
(RAKE in mobile)
Joint Detection
(RAKE in mobile)
3.84 Mcps
1.28 Mcps
3.84 Mcps
4-256
1, 2, 4, 8, 16
1, 2, 4, 8, 16
Fast: every 667µs
Slow: 200cycles/s
Slow: 100cycles/s
Frame structure
0.667/10ms
0.675/5ms
0.667/10ms
Timeslots/Frame
______
7
15
Bandwidth
Frequency Reuse
Handover
Modulation
Receiver
Chip rate
Spreading Factor
Power control