Biomedical Engineering Reference
In-Depth Information
their. (
..Consequently,.the.chance.of.QoS-violating.users.becoming.QoS-
satisfying. users. is. increased.. Also,. an. increase. of. rate. value. can. let. user. i .
enjoy.faster.service.without.affecting.the.QoS.of.other.users.
E
N b
o
)
E
N
b
CaseB:
< γ
, for
i
N
(i.e.,theQoSConstraintIsViolated)
i
o
i
Both. the. power. and. the. rate. genes. of. user i will. be. mutated.. The. changes.
of.the.power.and.the.rate.values.are.based.on.the.following.rules:.The.new
power. value. is. generated. randomly. between.
,. while. the. new
max
p P
i
,
i
.
The.purpose.of.these.changes.is.to.increase.the.transmission.power.and.to.
decrease.the.transmission.rate,.respectively..The.value.of. (
min
transmission.rate.is.generated.randomly.between.
R
,
r
i
i
E
N i
)
b
o .of.user i .is.then.
improved;.hence.the.chance.that.the.QoS.of.user. i is.satisied.is.increased..
However,. it. should. be. noted. that. increasing. power. may. cause. violation. of.
the. QoS. constraint. of. the. other. users. since. multiple. access. interference. is.
also.increased.
E
N
b
= γ
, for
i
N
CaseC:
(i.e.,theQoSConstraintIsJustSatisied)
i
o
i
Since. this. is. the. ideal. situation,. the. transmission. power. and. transmission.
rate. of. user i . will. remain. unchanged,. even. if. mutation. occurs.. In. fact,. any.
modification.will.cause.certain.adverse.effects.as.follows:
.
1.. An. increase. of. power:. The. QoS. constraints. of. other. users. may. be.
violated.since.the.increase.of.a.user's.power.will.increase.the.mul-
tiple.access.interference.of.the.others.
.
2.. A.reduction.of.power:.The.QoS.constraint.of.user. i may.be.violated.
.
3.. An.increase.of.rate:.The.QoS.constraint.of.user. i .may.be.violated.
.
4.. A.reduction.of.rate:.This.contradicts.one.of.the.goals.(i.e.,.the.maxi-
mization.of.total.rate).
In.summary,.the.new.mutation.is.operated.as.follows:
E
N
.
1.. After. crossover,. evaluate. (
. of. all. users. in. each. of. the. new.
b
o
)
chromosomes.
.
2.. Set.the.chromosome.counter. k .=.1.
.
3.. Set.the.user.counter. i .=.1.
.
4.. If.user. i .belongs.to.case.A,.complete.the.corresponding.actions.and.
go.to.step.7.
.
5.. If.user. i .belongs.to.case.B,.complete.the.corresponding.actions.and.
go.to.step.7.
.
6.. Otherwise,.keep.the.power.and.rate.genes.of.user. i .unchanged.
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