Self-organized Spectrum Chunk Selection Algorithm for Local Area Deployment

1
Self-organized Spectrum Chunk Selection
Algorithm for Local AreaDeployment

• Sanjay Kumar 1
• Yuanye Wang 2, Nicola Marchetti 2
• 1Birla Institute of Technology, Ranchi, India
• skumar_at_bitmesra.ac.in
• 2Aalborg University, Denmark
• ywa _at_es.aau.dk, nm_at_es.aau.dk

2
Contents

• Introduction
• Motivation and Objectives
• Algorithm
• Scenaion Description
• Performance Metrics
• Evaluation Parameters
• Performance Results
• Conclusions
•  

3
Introduction

• The IMT-A 4G systems with new capabilities
• To be operational around the year 2015
• Provide access to wide range of telecommunication
  services
• Target peak data rates 1 Gbps in DL and 500 Mbps
  in UL
• Focus on Local Area (LA) deployment scenarios
• The Wide Area (WA) deployment uses fixed
  frequency reuse schemes
• It needs proper network planning, such as
• Frequency reuse plans
• Base station location
• Controlling transmit power levels etc.
• The LA of IMT-A expected random and
  uncoordinated deployment
• Hence netwrok planning not feasible
• Also, possiblly Home Node Bs (HeNBs) share the
  available radio spectrum
• A mechanism is needed to assign spectrum in self
  organized manner and improve throughput
  performance
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•  

4
Motivation and Objectives

• Reuse 2 gives the highest throughput performance
  in LA deployment 11, but needs Network planning
• A mechanism is needed to achieve nearly same
  performance in random deployment 

Fig. 1. Possible chunk selection with reuse 2 in
random deployment
Fig. 2. Allocation for reuse 2 with optimal
network planning
To minimize the mutual inter-cell interference
among HeNBs with random and uncoordinated
deployment in order to improve throughput
performance .
5
Algorithm

• Steps
• Initialization
• Update chunk selection
• Interference consideration
• Chunk switch over

Figure 3 Flow chart of the Algorithm
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Algorithm Description
Spectral bandwidth is divided in two equal size
spectrum chunks (for considering to compare
with reuse 2)  Algorithm could be used for any
reuse schemes
Step 1 Initialization phase

• Random selection of a spectrum chunk
•  Initialization with sequence number
  switch-over number
•  Sequence number determines position in queue
•  Switch-over number helps to avoid dead lock
  situation
• It indicates the maximum of times a chunk is
  retained

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Algorithm Description (1)
Step 2 Condition to update the chunk selection

• The sequence number is reduced by one in each
  update interval
• This indicates HeNB turn to update its chunk
  selection 

 Step 3 Interference consideration for chunk
selection

• Comparison of interference levels over the chunks
• The UL-RIP is used as interference measurement
  yard stick
• UL- RIP is defined as the total power received
  over the spectrum chunk
•  The chunk selection is based on Abs (RIP1 -
  RIP2 ) gt P_Threshold
•  This ensures a sufficient amount of interference
  difference before decision
•  The threshold indicates a tradeoff between
• tolerable interference vs increased signaling
  requirement

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Algorithm Description (2)
Step 4 Switching over to other Chunk

• The chunk with minimum RIP is chosen

• Main features of the Algorithm
•  
• Uses UL- RIP (already standardized for LTE
  system)
•  Works in a random and uncoordinated deployment
• Requires very little signaling exchange
• Chunks allocation in sequence (avoids complexity
  in interference assessment)
• If of HeNBs is very high a long convergence
  time may be required
• Provides a scalable solution.
• Performance is upper-bounded by reuses 2 scheme
• Could be used for both DL UL
•  

9
Scenario Description
Figure 4 LA office indoor with 4 HeNBs

• HeNB Location center of each cell (also
  examined with randomized)
• HeNB coverage area . 50 x 25 m (consisting of 10
  rooms)
• Simulation method snap-shot based
• Several thousands snap-shots are simulated
• Users uniformly distributed locations
• Throughput Mapping SINR 8

10
Performance Metrics

• Average Cell Throughput Cell throughput averaged
  among all the simulated cells
• Cell Edge User Throughput The 5 user outage
  throughput , CDF value
• Chunk Selection Interval Time period for one
  chunk selection operation.
• 
  It contains an integer number of transmission
  frames.

• Some simplifications are also assumed
• No power control
• Round Robin for frequency domain scheduling
• Fast fading not considered

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Simulation Parameters
PARAMETERS SETTINGS Spectrum allocation 100
MHz at 3.5 GHz Access schemes DL OFDMA, UL
SCFDMA Duplexing Schemes TDD UEs per Cell
510 Total Transmit Power 24dBm Receiver
Noise Figure 7-9 dB Room Size 10x10
m Corridoor width 5 m Internal walls light
attenuation (5dB) Shadow fading LOS 3dB,
NLOS 6dB (SD) Path Loss models LOS 18.7 log10
(d) 46.8 20log10 (f /5.0) NLOS 20 log10
(d) 46.4 nw Lw 20log10 (f
/5.0) where, d direct-line distance
(m) f carrier frequency (GHz) nw of
walls between Tx Rx Lw wall attenuation
(dB)
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Performance Results (1)
DL Average Cell Throughput

• Improved compared to reuse
• 1 and 4 schemes
• Slightly lower compared to
• reuse 2 scheme
• Reuse 2 needs planning for
• optimal performance.
• Proposed algorithm performs in
• self- organized manner with
• random and un-coordinated
• deployment

Figure 5 Comparison of DL Average Cell
Throughput
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Performance Results
Performance Results (2)
DL Cell Edge User Throughput

• significantly higher
• compared to reuse 1
• scheme (200 300 )
• Nearly same as reuse
• 4 scheme
• However lower than
• reuse 2 scheme

Figure 6 Comparison of DL Cell Edge User
Throughput
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Performance Results
Performance Results (3)
Convergence Time
The performance is stabilized after 10
selection intervals, with Significant
Improvement
Figure 7 Convergence Time of the Algorithm
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Performance Results
Performance Results (4)
Randomized HeNB Locations

• It may be difficult to control HeNB locations
• Especially in home scenarios
• Nearly the similar performance is realized

With the same chunk allocation as DL, The similar
performance has been realized in UL also
Figure 8 DL Average Cell Throughput with
Randomized HeNB Locations 
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Conclusions

• An Algorithm for self organized spectrum chunk
  selection has been proposed
• It minimizes mutual inter-cell interference and
  improves the system throughput performance
• Performance approaches fixed frequency reuse 2
  scheme
• Gives much better performance than fixed
  frequency 1 and 4 schemes
• Suitable for LA with large scale random and
  uncoordinated deployment
• Works with very limited signaling exchange
• Needs no additional measurements than what is
  already established for the LTE
• The main features of the algorithm are
  scalability and operation simplicity

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• Thank You