Resource Management in WCDMA - Multiobjective Optimization Methodology: A Jumping Gene Approach - page 154

be.designed.but.can.only.jump.within.the.specified.range.through.the.cut-
and-paste.or.copy-and-paste.operation.
For.example,.as.shown.in . Figure 7.1 ,. assuming.that.there.are.six.connect-
ing. users. in. the. system,. the. ranges. of. the. transmission. power. gene,. voice.
user. transmission. rate. gene,. data. user. transmission. rate. gene,. and. video.
user.transmission.rate.gene.are.between.gene.1.and.gene.6,.between.gene.7.
and.gene.8,.between.gene.9.and.gene.10,.and.between.gene.11.and.gene.12,.
respectively..A.chromosome.will.be.infeasible.if.genes.jump.to.any.position.
outside.their.corresponding.ranges..Therefore,.the.jumping.positions.must.
be.restricted.

7.6 Mutation
In.this.problem,.the.conventional.mutation.method.did.not.perform.well,.as.
it.cannot.effectively.improve.the.QoS.of.those.QoS-violating.users.appearing.
in.a.chromosome..First,.this.is.because.the.operational.rate.is.usually.small;.
hence. only. a. small. number. of. QoS-violating. users. may. have. their. trans-
mission.power.and.transmission.rates.altered..On.the.other.hand,.if.a.high.
mutation.rate.is.set,.the.GA.changes.to.possess.a.random.searching.behavior.
and.no.longer.is.properly.guided..Second,.even.if.the.genes.have.undergone.
mutation,.it.cannot.be.guaranteed.that.improvement.always.happens.if.the.
gene.is.simply.replaced.by.some.random.values.
To.overcome.these.problems.and.improve.searching.performance,.a.new.
mutation.operation.is.introduced..Three.different.cases.are.considered,.and.
the.decision.of.how.the.transmission.power.and.transmission.rate.are.to.be.
changed.is.based.on.the.value.of. (

E
N b
o

.(see.Section.7.2),.that.is,.whether.the.
QoS.constraint.of.the.users.is.satisfied.or.violated.

)

CaseA:

E
N

b

> γ

i , for

i ∈ N (i.e.,theQoSConstraintIsSatisied)

o

i

The.transmission.power.or.transmission.rate.genes.of.user i will.be.mutated.
if. the. corresponding. random. number. is. less. than. the. mutation. rate pm ..
Let.the.current.gene.values.for.transmission.power.and.transmission.rate.
of.user i .be. p i .and. r i ,.respectively;.a.new.transmission.value.is.applied.by
generating.a.random.number.within.the.range.of.

,.and.the.trans-
mission.rate.is.replaced.by.a.new.random.value.obtained.within.the.range
of.

min

P , p

i i

.
This. design. tries. to. decrease. the. transmission. power. and. increase. the.
transmission.rate.of.a.user,.respectively..This.is.because.power.reduction.can.
decrease.the.multiple.access.interference.of.other.users.and.hence.increase.

max

r R
i

,

i