5 load control

7/28/2019 5 Load Control

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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential

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Load Control

340315,7340315,7




Chapter 1 Load Control presentation

Chapter 2 Load control algorithms

Chapter 3 Call Admission Control




Load Concept

• Load:

The occupancy of capacity

TDMA and FDMA system: the capacity is hard

limited.

Example: In GSM, the cell capacity (channel

number) is fixed.

CDMA system:

soft capacity

Hard capacity




Load Concept

Time

Frequency

FDMA

User#1

User#2

User#3

User#1User#2

User#3

Frequency

Time TDMA

Frequency

Time

Code CDMA

User#1

User#2

User#3




Capacity of CDMA system

• Soft capacity:

Interference (UL)

Power (DL)

• Hard capacity

Code

Hard ware resource

Transport resource, NodeB processing capability.




Load Control Algorithm(1)




Load Control Features(1)




Load Control Features(2)




Principle of the Admission Control

Before accepting any request the RNC checks :

•Radio Interface Resource

•IUB Transmission Resource

•CE resource

•Code resource




call arrive

Get the service characteristic and the current load

Suppose the user is accepted, and calculate the predicted

UL load factor. And then compared with the threshold.

admitted?

Suppose the user is accepted, and

calculate the predicted DL load factor.

And then compared with the threshold.

admitted?

call admitted call rejected

end

n

y

y

n

Flow Chart of Admission Control




Principle of the Admission Control




• Activity factor : The percentage of time that the datatransmission is active.

• The UL and DL activity factor may be different for dedicated channel.

• Different service type has different activity factor.

Activity factor




• Eb/No

j

j

b

P RTWP

P

R

W

power ce Interferen

power Signal

gain g proces N E

sin/ 0

RTWP

N E RW

P

b

j

0/)/(1

1

0/

)/(

1

1

N E

RW L

b

j

cell theinuser all j

jUL L f )1(

• Received power Pj

• Define load factor for user j

• UL load factor

Admission Control UL Algorithm




Admission Control UL Algorithm 1

Admission request

Smaller than the

threshold?

admitted

y

end of UL CAC

rejected

n

Get current RTWP, and calculate the

current load factor. RTWP

P N UL 1

Get the traffic characteristic, and

estimate the increment of load factor

R N

E

W

b

0

1

1

Calculate the predicted load factor.

0 _ UL predicted UL




Admission request

Smaller than the

threshold?

admitted

y

end of DL CAC

rejected

n

Get current TCP. )( N P


estimate the increment of tcp. P

Calculate the predicted tcp. comm P P N P )(

Admission Control DL Algorithm 1




• Reference service : 12.2k AMR with activity factor = 1.

• Normalized traffic factor of user i :

dard sc

ic

i N E

N E k

tan0

0

• Normalized traffic factor(NTF) has the meaning of equivalent number of user i relatives to the 12.2k AMR.

• UL and DL may have different normalized traffic factor.

Normalized traffic factor




Admission request

Smaller than the

threshold?

admitted

y

end of UL/DL CAC

rejected

n

Get current total NTF.

N

i

ik N K 1

)(


estimate the increment of NTF.

dard sc

N c

N N E

N E k

tan0

10

1

Calculate the predicted NTF. 1)()1( N k N K N K

UL & DL Algorithm2




• Only for dedicated channels, and reserve a certainresource for the common channels.

• UL and DL CAC algorithms are independently.

• In principle, a request will be admitted only when UL and

DL are both admitted. But if UL or DL CAC switch is closed,

only one direction CAC also can be realized.

Strategies




• Handover threshold, conversational threshold and other

services threshold are used to keep the priority of the handover

higher than the conversational, conversational than the Best

Effort services.

• For RRC Connection request with the reason : registration,

emergency call and Detach direct admission is used.

• For RRC Connection request with the reason

“Originating/Terminating Conversational call “ the thresholds for

AMR voice services are used.

Strategies

• For RRC Connection request with other reason, UL/DL OLC Trigger

threshold is used when using algorithm 1. when using algorithm 2 the

same threshold is used if OLC switch is off unless the connection will

be rejected if the cell is in an overload congestion state.



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