A Cross-Layer Optimization Mechanism for Multimedia Traffic over IEEE 802.16 Networks A Cross-Layer Optimization Mechanism for Multimedia Traffic over IEEE 802.16 Networks

A cross-layer optimization mechanism for IEEE 802.16 metropolitan area networks.
Modern communication systems is the parameterized operation at different layers of the protocol stack.
A cross-layer optimization mechanism that interacts with the Physical (PHY), Medium Access Control (MAC), and Application layers.
IEEE 802.16

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LOGO
QoSQuality of Service
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Architectural Framework
The cross-layer optimization which consists of N layers and a cross-layer optimizer .
The optimization process is performed in three steps:
Layer abstraction
  
Architectural Framework
In general, the different parameters can be divided in four main types:
Directly Tunable (DT)
Indirectly Tunable (IT)
SS /

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Information Flow
Channel Measurements
The BS needs information regarding the quality of the signal received by the SSs.
by each SS on the uplink.
Channel Quality Information Channel (CQICH)



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B. Traffic Rate Adjustments
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The Proposed Mechanism
In case most of the losses are due to poor channel conditions (packet errors)
the BS part instructs the MAC layer for a degradation of the modulation, in order to achieve higher channel error resilience and increase robustness against interference.
In case most of the losses are the result of packet timeouts (unacceptable delays)
a. If the loss rate is caused almost exclusively by packet timeouts
b. In different case, when a significant percentage of packet losses are caused by errors due to the poor channel conditions
1 2 3 3 4 CINRIEEE 802.16PHY [ 8 ] MACSSUL - MAPMAC
 
 
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The Proposed Mechanism
If the mean delay is relatively low compared to the delay bound
If the mean delay is close to the delay bound
SS  
2  
SS/MAC 3 3 4 4 SS 4 3 5 4 SS 5 3 6 4
AMR [ 9 ] [ 10 ] 7 4 [ 11 ] piggybacked  

CINR[ 8 ]  
ModelerSS 
Simulation Model And Results
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LOGO
Conclusion
LOGO
Conclusion
With the aid of a detailed simulation model, we showed that the use of the proposed optimization mechanism leads to an efficient exploitation of the adaptation capabilities, resulting in considerably reduced packet loss rates and improved system’s capacity, especially under heavy traffic conditions.
IEEE 802.16PHYMAC 
 
FEC ARQ
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