Adaptive Resource Allocation in Multiuser OFDM Systems

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Adaptive Resource Allocation in Multiuser OFDM
Systems
Malik Meherali Saleh EE 381-14 May 05,
2005 (05/05/05)
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Introduction

• Future Generation (4G) systems to provide high
  data rates
• Issue Inter-Symbol Interference (ISI)
• Multiple Input Multiple Output (MIMO) and
  Orthogonal Frequency Division Multiplexing (OFDM)
  to the rescue
• Resource Allocation
• Margin Adaptive Wong, Cheng, Letaief and Murch,
  1999
• Rate Adaptive Jang and Lee, 2003
• Rate Adaptive proportional fairness Shen,
  Andrews and Evans, (Draft) 2004

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Subcarrier Gain
Channel Magnitude
Tones
Tones
Channel Magnitude
User 2
User 1
These figures have been created for better
understanding of algorithm. They are NOT results
from simulations
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Algorithm for Jang and Lee

• Initialization
• Set Rk 0 for k1K
• For n 1 to N
• Find the user k having higher channel gain
• Update Rk
• For Power Allocation
• Water-filling
• Equal power allocation (Ptotal/N)

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Subcarrier allocation
Channel Magnitude
Channel Magnitude
Tones
Tones
These figures have been created for better
understanding of algorithm. They are NOT results
from simulations
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Algorithm for Prof. Evans et al

• Initialization
• Set Rk 0, Wk 0 for k 1 to K and A
  1,2,,N
• Y1Y2YK
• For k 1 to K
• Find n satisfying h(k,n) gt h(k,j) for all j e A
• Let Wk Wk U n, A A-n and update Rk

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Algorithm for Prof. Evans et al Conti..

• While A ! empty
• Find k satisfying Rk/Yk lt Ri/Yi for all I,
  1ltiltK
• For the found k, find n satisfying h(k,n) gt
  h(k,j) for all j e A
• For the found k and n, let Wk Wk U n, AA-n
  and update Rk

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Implementation

• For Non Fair System
• Code Development in progress
• For Fair System
• A Low Complexity Algorithm for Proportional
  Resource Allocation in OFDMA Systems Ian Wong
  et al
• Linearizes power allocation
• Approximates rate proportionality

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Results
Normalized Rate Proportions
User Number (k)
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Results Conti
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Future Work

• Implement code for first method
• Compare the two methods on the following
• Total Capacity
• Normalized data rate for individual user
• Complexity