Rate Adaptive MultiCode MultiCarrier CDMA Systems in Multipath Fading Channel

1
Rate Adaptive Multi-Code Multi-Carrier CDMA
Systems in Multipath Fading Channel
Mar. 26th, 2003
CDMA team (JAEWEON, TAEYOON, SRIVATSAN, MADHULIKA)
2
Introduction

• Objective
• Spectrally efficient data transmission in
  wireless system
• Adaptive data rates
• Propose
• Enhancement to multi-code CDMA systems by using
  multi-carrier schemes
• Approach
• Evaluate performance in frequency selective
  fading channel
• Compare the three systems

3
Multi-code CDMA system

• Depending on the M-ary data symbol one of the M
  sequences is transmitted
• Increase data rate by increasing the size M of
  the sequence set

Cited rom H.D.Schotten, H.Elders-Boll, A,Busboom,
Adaptive Mutli-Code CDMA for variable Data
Rates, IEEE International Conference on Personal
Wireless Communications 1997, pp. 17-19, Dec.
1997
4
Multi-code Multi-carrier CDMA system

• Spread the selected code using a user specific
  spreading code, and then modulate a different
  subcarrier with each chip

5
Multi-code Multi-carrier DS-CDMA

• Serial-to-parallel convert the selected sequence
• Spread the sequence by a user specific spreading
  code
• Modulate a different subcarrier

6
Expected Outcomes

• Multi-code system has severe degradation in
  frequency selective fading channel
• Better BER performance for Multi-code
  Multi-carrier system than the multi-code system
  in fading channel
• Find the best code for the sequence sets in
  fading channel