Cooperation Possibilities for

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Cooperation Possibilities for TD-SCDMA
Enhancement
2001.12.14.
IMT-2000 System Development Division Radio
Broadcasting Technology Laboratory, ETRI
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Contents

• Introduction
• Achievements in TDD
• TDD modem simulator
• Packet Transmission
• Performance improvement of Wideband TDD by Smart
  antenna and MUD
• System-level simulator/interference simulator
• RRM
• Future works in TDD
• Core technology of TD-SCDMA
• Future Possible Co-operation

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• Introduction
• TDD in Korea
• Major Difference between FDD and TDD

4
Current status of TDD in Korea

• RD history on TDD mode
• There was no research activity for TDD mode in
  Korea until 2000.
• We have been under way of the 2 years TDD
  project from 2000.7.
• Mainly focused on RD of the core technology of
  TDD mode
• Preparation for the FDD/TDD dual mode handset
  development after 2002.
• Funded by government, 2 operators and 3
  manufacturers.
• SK IMT, KT ICOM
• LG IC, SAWNET, Giga CE
• Major research area
• Implement Floating-point simulator for TDD
  physical layer.
• High-Speed Packet transmission technology
• Performance enhancement (MUD, SA, Power Control
  .)
• Radio resource management

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Major Difference between FDD and TDD
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• Achievements in TDD
• TDD modem simulator
• H-ARQ
• Performance Enhancement by Smart Antenna
• Mitigation of Interference by MUD
• System-level simulator
• Interference simulator
• RRM

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TDD Modem simulator

• Block Diagram of TDD modem simulator
• Rel. 4
• 1 sample/ chip
• Include Multiple user
• Fixed searcher mode
• Documentation of High Level Design for Future
  Commercial TDD modem
• Future Integration
• AFC/AGC
• Interference Mitigation technologies

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Improved Channel Estimation

• Investigate the current Channel estimations in
  TDD mode
• Cyclic correlator/ Matched filter/ FFT based
  estimator
• Problem
• When fast fading, they show degraded performance
  due to Random FM.
• Proposed Channel Estimator to use data part

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Initial Cell Acquisition and AFC in TDD mode

• Initial Cell Acquisition
• Target minimum cell acquisition time with low
  complexity
• Investigated the performance by conventional
  method
• Need more time and hardware to acquire the system
  due to Infrequent transmission of sync code
• Propose an improved cell acquisition algorithm to
  reduce the acquisition time
• AFC
• Target minimum acquisition time with small
  variance
• Investigated the performance by conventional
  method (Cross-product, DFT) in TDD mode
• Degraded performance and more acquisition time
  compared to FDD mode due to midamble location and
  discrete transmission of midamble
• Under investigation of novel algorithm for the
  discrete transmission of reference signal to
  minimize the acquisition time.

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H-ARQ technology

• Target Improved throughput with low delay and
  complexity
• Investigate and conclude the current H-ARQ
  schemes based on Turbo code
• Full IR gt Partial IR gt Chase CombininggtNo H-ARQ
• Propose Novel Adaptive H-ARQ

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H-ARQ technology

• Results of Propose Adaptive H-ARQ
• Improved adaptation to fast fading variation
  compared to conventional H-ARQ with fixed code
  rate.
• When we use this technique with Chase Combining
  with lowest complexity among H-ARQ, it shows the
  closer performance as Full IR.

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Performance Enhancement by Smart Antenna

• Key features of ETRIs Smart Antenna system
• Chip Level Beamforming scheme
• Beamforming is conducted before despreading, it
  gives better performances over Symbol Level
  Beamforming.
• Low complexity and low power consumption than in
  SL BF-based array transceiver
• Temporal Reference Beamforming scheme
• Use the user specific midamble code as the
  reference signal
• Open loop type S-T array transceiver structure
• Subspace beamforming is proposed for downlink
  beamforming
• JD (Joint Detection) for co-located users
• performance improvement by beamforming and joint
  detection

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Performance Enhancement by Smart Antenna

• Model example of TDD S-T array transceiver
• MMSE BF-based in Uplink

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Performance Enhancement by Smart Antenna

• Enhanced hybrid system with SA and JD in TDD

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Interference Mitigation by MUD

• Joint Detection
• Zero Forcing-Block Linear Equalizer with/without
  DF
• MMSE-Block Linear Equalizer with/without DF
• Multi-step PIC
• Use Virtual Pilot and Channel ordering and
  improved Channel estimation

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System level simulator

• Design and Implement the system level simulator
  based on TDD mode
• Strictly follow ITU-R and 3GPP recommendations
  including WWW traffic model
• Use FER prediction to reflect the link-level
  results into the simulator
• Very suitable for the evaluation of packet
  traffic and RRM

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System level simulator

• Basic element of System level simulator

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Interference simulator

• Interferences in TDD system
• Interference from adjacent slots of different
  NodeB due to Synchronization Error
• Interference from different links on the same
  Timeslot due to different switching point
• Design and Implement the Interference simulator
  in TDD system

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Radio Resource Management

• RRM is essential part in TDD system due to
  asymmetric and/or changing data services
• Fast DCA
• Adaptive code bank management from the knowledge
  of interference and available code.
• Slow DCA
• Adaptive Timeslot allocation scheme when there
  are different switching point between NodeBs

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• Future works in TDD

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Future Work Items

• Implement Floating-point TDD Modem simulator
• AFC/AGC
• Uplink Random Access
• Packet Transmission
• AMC, H-ARQ, and FCS suitable to channel variation
• MIMO based Packet transmission
• Performance Enhancement
• Smart Antenna to exploit channel reciprocity
• Enhanced MUD
• Hybrid system with Smart Antenna and MUD
• Optimum Combining
• Optimum Tx Diversity with Power allocation scheme
• MIMO based system

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Future Work Items

• RRM
• Enhanced system-level simulator to include FCS
  and AMC
• Interference evaluation between different
  systems to get optimum guard band and range
• Packet Scheduler

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• Future Cooperation
• Difference between two TDD modes
• Cooperative area and way

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Difference between Two TDD modes
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Difference between Two TDD modes
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Cooperative area and way

• Cooperative area
• Performance enhancement technology
• Smart antenna and MUD or Hybrid system
• Tx Diversity
• Enhanced capability based on MIMO technology
• Packet related issues
• AMC/FCS/H-ARQ
• Packet scheduler
• Optimum Spreading code in Uplink and Downlink
• Generation of spreading codes for lowering
  inter-cell interferences
• Utilization method of chosen spreading codes
  suited for enhanced TDD-based CDMA systems
• Cooperative way
• Joint Project or conference
• Engineer Exchange Program
• Cooperation for standardization