Dynamic Channel Allocation and Power Control
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Transcript of Dynamic Channel Allocation and Power Control
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2007 WNRL/KWU 1
Dynamic Channel Allocation and Power Control
M. Schwartz
Mobile Wireless Communications
Chapter 4
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2007 WNRL/KWU 2
DCA & PC
• Methods used to improve (cellular) system performance
• DCA– Dynamic Channel Allocation
– Reducing call blocking probability
• PC– Power Control
– Reducing interference
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2007 WNRL/KWU 3
FCA vs. DCA
• Fixed Channel Allocation
• Many DCA algorithms proposed
• Low/moderate traffic– All DCA schemes outperform FCA
• Heavy traffic– Few channels are free
– Channel locking due to the reuse constraint
– FCA is better
• Hybrid schemes proposed
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2007 WNRL/KWU 4
Channel Locking & Directional Locking
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2007 WNRL/KWU 5
BDCL DCA
• Borrowing with Directional Channel Locking
• Proposed by Zhang & Yum
• Specification of lock directions
• Channel ordering– Lowest numbered channel has the highest priority to the local call
– Highest numbered one has the highest priority to be borrowed
• Immediate channel reallocation– Pack channels used by local calls closely together
– Borrowed calls are packed together as well
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2007 WNRL/KWU 6
Borrowing of channels does not propagate
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2007 WNRL/KWU 7
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2007 WNRL/KWU 8
How many possible states in total?
6
]1)12(2)[22)(12(12
1
2
mmmk
m
k
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2007 WNRL/KWU 9
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2007 WNRL/KWU 10
Blocking Probability of Cell i
mxxmxx
i xmxxPxxmxPB2
1212
311
2131
)2,,(),2,(
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2007 WNRL/KWU 11
How to calculate P(x1,x2,x3) ?
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2007 WNRL/KWU 12
Product-form Solution
states) blocking(PBi
3
1
1321 !),,(
j j
xj
x
AGxxxP
j
states all
3
1
)!
(j j
xj
x
AG
j
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2007 WNRL/KWU 13
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2007 WNRL/KWU 14
Homework
• Problem 4.3
• Problem 4.4