2007 WNRL/KWU 1

Dynamic Channel Allocation and Power Control

M. Schwartz

Mobile Wireless Communications

Chapter 4

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

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

2007 WNRL/KWU 4

Channel Locking & Directional Locking

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

2007 WNRL/KWU 6

Borrowing of channels does not propagate

2007 WNRL/KWU 7

2007 WNRL/KWU 8

How many possible states in total?

6

]1)12(2)[22)(12(12

1

2

mmmk

m

k

2007 WNRL/KWU 9

2007 WNRL/KWU 10

Blocking Probability of Cell i

mxxmxx

i xmxxPxxmxPB2

1212

311

2131

)2,,(),2,(

2007 WNRL/KWU 11

How to calculate P(x1,x2,x3) ?

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

2007 WNRL/KWU 13

2007 WNRL/KWU 14

Homework

• Problem 4.3

• Problem 4.4