1 Radio Resource Allocation for Global System for Mobile Communications
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 1/82
1
Radio Resource
Allocationfor
Global System for MobileCommunications
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 2/82
2
Reference (1/2)
[1] ETSI/TC, “Digital cellular
telecommunications system (Phase 2+); GSMPublic Land Mobile Network (PLMN) access
reference configuration”, GSM Tech. Spec.GSM 04.02 Version 5.0.0, ETSI May1996.
[2] Eberspacher, J. and Vogel, H.-J. GSM
Switching, Services and Protocols, JohnWiley & Sons Ltd, England, 1999.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 3/82
3
Reference (2/2)
[3] Milosh, I., Moshe, Z., Paul, F. and Maxim, G.
Performance Between Circuit AllocationSchemes for Half- and Full-Rate Connections
in GSM. IEEE Trans. on Vehicular
Technology , 47(3):790-797, August 1998.
[4] Lin, Y.-B., “Performance Modeling for Mobile
Telephone Networks,” IEEE Trans. on
Vehicular Technology , vol. 47, pp. 790-797,
August 1998.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 4/82
4
Outlines
Introduction
Improving GSM Call Completion by CallReestablishment
Channel Assignment for GSM Half-Rate andFull-Rate Traffic
Channel Allocation for GPRS
Conclusions & Future Works
Publication Lists
今天要報告的主題共分為四大部份:
先對 GSM系統做簡單的介紹
接下來報告我對 GSM Radio Resource Allocation所做的兩大研究 “Improving
GSM Call Completion by Call Reestablishment” , “Channel Assignment forGSM Half-rate and Full-rate Traffic”.
最後我針對 Future Work: Channel Allocation for GPRS Packet Data加以闡述.
在這三個 Topic中
Improving以及 Channel Assignment是針對 Circuit Mode的 Traffic加以分析.
Channel Allocation是針對 Packet Mode的 Traffic做研究.
而 Channel Assignment以及 Channel Allocation可用類似的Modeling
Technique.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 5/82
5
Introduction (1/4)
Global System for Mobile Communication
(GSM) is a standard adopted by cellularsystems widely developed in Europe and
Asia.
GSM combines TDMA and FDMA
technologies for radio channel allocation.
• A frequency carrier is divided into eight time slotsper frame, which are used to support speech anddata transmission.
Global System for Mobile Communication (GSM)系統是亞洲地區以及歐洲地區廣範被使用的 PCS系統.
它在 Air Interface所採用的技術是 TDMA (Time Division Multiple Access)以
及 FDMA (Frequency Division Multiple Access).在每個 Frequency Carrier上再依時間軸切分為 Frame.每個 Frame具八個Time Slot.
每個Time Slot即為一 Channel.
也就是在一個 Frequency Carrier上可以容納 8個使用者.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 6/82
6
Introduction (2/4)
MS: Mobile StationBTS: Base Transceiver Station
BSC: Base Station ControllerBSS: Base Station SubsystemMSC: Mobile Switching Center
PSTN: Public Switched Telephone NetworkHLR: Home Location Register
VLR: Visitor Location RegisterAUC: Authentication CenterOMC: Operation and Maintenance Center
BTS
BTSBTS
BTS
BTS
BTS
BSC
BSC
MS
MSAbis interface
Um interface
MSC
Base Station Subsystems
A interface
HLR VLR AUC
PSTN
OMC
Operating Subsystem
Network Switching
Subsystem
GSM Architecture
MS可經由 Radio Interface與 BTS連結.
BSC負責控至數個 BTS.
MSC為一 Switch負責將通話 Route PSTN.
HLR,VLR,為資料庫用來存放MS的位置.
AUC負責產生以及存放 Security-related的資料,例如用來任證與加密的 Key.
OMC負則監控目前網路的正常運作.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 7/82
7
Introduction (3/4)
GSM Communication Setup
• An MS initiates a communication session bymaking an access request to a BSC if the MS is inthe cell. If no free channel, the call is blocked.
GSM Handoff Operation
• If the MS moves to another cell duringconversation, the radio link to the old BSS isdisconnected, and a radio link to a new BSS isrequired. If the new BSS has no idle channels, the
call is forced to terminate.
一個Mobile Station可經由
Communication Setup的程序來接續上 GSM網路.
它的運作方式是
(i) 由MS經由 Radio Interface向 BSC發出Access Request.
(ii) 若目前沒有 Idle的 Channel則此通Call會被Block 掉
若在通話中,因Mobile Station移動的關係移出了原先通話的 Cell.則會啟動Handoff Operation.
它的運作方式是
(I) MS先中斷與舊BSS間的無線電聯結.
(ii)再與新的BSS建立無線電聯結,若新的 BSS沒有IDLE的Channel供此
Handoff Call使用,則這通電話便被強迫斷話.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 8/82
8
Introduction (4/4)
The services offered by the GSM system arelimited to voice and low-speed data.
GSM Spec. phase 2+ is defined for better QoSand network quality perception, e.g.,• Advanced Speech Services
• General Packet Radio Service
Compared with the voice circuit-switchedservices, new services generate new type oftraffic.
Our objective is to allocate the radio channelsto both new and traditional service users in anefficient way.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 9/82
9
Research 1:
Improving GSM CallCompletionby Call Reestablishment
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 10/82
10
Call Interruption (1/2)
Call Interruption Phenomenon:• A radio link may be temporarily disconnected due
to obstacle shielding.
GSM call reestablishment service:• If a communication channel is interrupted, the
network still reserves the trunk and/or the channelfor the interrupted call, and an interruption timer istriggered.
• If the timer expires or the remote party hangs upthe phone before the interruption period is over,
the interrupted call is actually forced to terminate.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 11/82
11
Call Interruption (2/2)
GSM call reestablishment service:• Otherwise, the interrupted call is resumed by the
call reestablishment mechanism. This serviceincreases end user satisfaction and networkquality perception.
In this research, we investigated three callRe-EStablishment (RES) mechanisms for thisservice.• Re-EStablishment 1 (RES 1)
• Re-EStablishment 2 (RES 2)
• Re-EStablishment 3 (RES 3)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 12/82
12
Re-EStablishment 1 (RES 1)
A call interruption timer is implemented in theBSC.
The BSC reserves the radio resource for theinterrupted call before the call interruption timerexpires.
The link between the MSC and the other callparty is reserved before the call interruptiontimer expires.
The interrupted call cannot be re-established if
the MS moves to another BSS during theinterruption period.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 13/82
13
RES 1 Message Flow: Intra-BSS Call Re-establishment
MS BSS0 MSC
Call is interrupted in this period
Timer starts
Timer stops1. call re-establishment request
Call is re-established at BSS0
2. call re-establishment request
acknowledgement
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 14/82
14
RES 1 Message Flow: RadioResource Release
MS BSS0 MSC
Call is interrupted in this period
Timer starts
Timer expires1. radio interface failure
2. clear command message3. clear complete message
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 15/82
15
Re-EStablishment 2 (RES 2) [1][2]
A call interruption timer is implemented in theMSC.
The BSC releases the radio resource for theinterrupted call when the interruption occurs.
The link in the MSC to the other call party isreserved before the call interruption timerexpires.
The interrupted call cannot be re-establishedif the MS moves to another BSS during the
interruption period.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 16/82
16
RES 2 Message Flow: Intra-BSS CallRe-establishment
MS BSS0 MSC
Call is interrupted in this period
Timer starts
Timer stops
1. Clear Request [radio interface failure]
Call is re-established at BSS0
9. call re-establishment request
acknowledgement
2. Clear Command
3. Clear Complete
4. call re-establishment request
5. Cipher Mode Command
6. Cipher Mode Complete
7. Assignment Request
8. Assignment Complete
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 17/82
17
Re-EStablishment 3 (RES 3)
A call interruption timer for the interrupted callis implemented in the BSC.
The BSC reserves the radio resource for theinterrupted call before the call interruptiontimer expires.
The link in the MSC to other call party isreserved before the call interruption timerexpires.
The interrupted call may be re-established if
the MS moves to another BSS after theinterruption period.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 18/82
18
RES 3 Message Flow: Intra-BSS CallRe-establishment
MS BSS0 MSC
Call is interrupted in this period
Timer starts
Timer stops1. call re-establishment request
Call is re-established at BSS0
2. call re-establishment request
acknowledgement
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 19/82
19
RES 3 Message Flow: Inter-BSS CallRe-establishment
MS BSS0 MSC
The call is interrupted in
this period, and the MS
moves to
BSS1
BSS1
1. call re- establishment request
5. Cipher Mode Command
2. call re- establishment
request3. clear command message
The call is re-established on the
link at BSS1
Timer stops
Timer starts
4. clear complete message
6. Cipher Mode Complete
7. Assignment Request
8. Assignment Complete
9. call re- establishment
request acknowledgement10. call re- establishment request acknowledgement
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 20/82
20
RES 3 Message Flow: RadioResource Release
MS BSS0 MSC
Call is interrupted in this period
Timer starts
Timer expires1. radio interface failure
2. clear command message3. clear complete message
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 21/82
21
Performance Evaluation: Output
Measure
Analytical Models (for RESs1, and 3) andSimulation Models (for RESs 1, 2, and 3)
were built to investigate the performance forRES mechanisms.
P nc : the probability that the call is notcompleted due to• new call blocking
• force termination due to handover
• force termination due to call interruption
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 22/82
22
Performance Evaluation: InputParameters
λo: new call arrival rate to a cell
1/ µx: the mean of conversation period 1/ µy: the mean of interruption period
1/ µz: the mean of the time period between when the
interruption begins and when the first of the following
two events occurs (i) the interruption timer expires and
(ii) the remote party hangs up the phone
α: the probability that at the end of a conversation period,
the radio channel is interrupted
1/ η: the expected cell residence time
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 23/82
23
Timing Chart
tc
x1 y1 x2 y2 x3
τ m tm,1
call arrival call completion
enter cell 0 move to cell 1 leave cell 1
tm,0
x j y j xk
x j
tm,i
tc,i
… …
…enter cell i leave cell i
time
z1 z2 z j
*
*
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 24/82
24
CASE (I)
tk
x1 y1 x2 y2 x3
τ m
call arrival
enter cell 0 enter cell 1
tm,0
xk yk
time
z1 z2 zk
xk+1
The MS moves to cell 1 during theconversation period.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 25/82
25
CASE (II)
x1 y1 x2 y2 x3
τ m
call arrival
enter cell 0 enter cell 1
tm,0
xk+1 yk+1…z1 z2 zk+1
the call can be resumed
tD,k
The call is re-established at cell 0 after theMS leaves the shielding area.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 26/82
26
CASE (III)
tD,k
x1 y1 x2 y2 x3
τ m
call arrival
enter cell 0 enter cell 1
tm,0
yk xk+1
z1 z2
yk+1
zk+1zk
The interruption period ends before theinterruption timer expires, and the remote
party does not hang up the phone
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 27/82
27
CASE (IV)
tc'
x1 y1 x2 y2 x3
τ m
call arrival
enter cell 0 enter cell 1
tm,0
xk+1 yk+1
time
z1 z2 zk+1
the call cannot be resumed
tD,k
The user hangs up the phone beforethe interruption period is over.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 28/82
28
CASE (V)
call arrival
tD,k
x1 y1 x2 y2 x3
τ m
enter cell 0 enter cell 1
tm,0
yk xk+1
time
z1 z2
yk+1
zk+1zk
The interruption period ends after the
interruption timer expires or after the
remote party hangs up the phone.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 29/82
29
Analytic Model for RES 1
Pb: the probability that all channels are busy when a call (either anew call or a handoff call) arrives.
Let Ph,1
(Ph,2
) be the probability that a connected new (handoff) callat the cell will hand off to the next cell.
Let Pi,1 (Pi,2) be the probability that a connected new (handoff) call atthe cell will be disconnected due to interruption.
( )( )y x y x
y
hh occurs RESin I CASE PPµ αβµ µ η µ η
η η
−++
+=== ]1)(Pr[2,1,
( )
( )( ) ( )( ) y x y x
x
y x y x
y x
ii occurs RESinV or III CASE occurs RESin IV CASE PP
µ αβµ µ η µ η
η αµ
µ αβµ µ η µ η
µ β αµ
−+++−++
−
=
+==
1
]1)()(Pr[]1)(Pr[2,1,
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 30/82
30
Analytic Model for RES 1: Derivationfor Pb (1/2)
The net trafficρ is derived as follows
The blocking probability Pb is expressed as
Pb is obtained by assigning a initial λ h and the IterativeAlgorithm
][][
][)1(][)1(
2,1,
2,1,
cihihcinio
chihcnio
t E Pt E P
t E Pt E P
λ λ
λ λ ρ
++
−+−=
∑=
=c
i
i
c
b
i
cP
0
)! / (
)! / (
ρ
ρ
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 31/82
31
Analytic Model for RES 1: Derivationfor Pb (2/2)
tcn: the channel occupation time of a new call thatis either complete in a cell or handed off to the
next cell.
tch: the channel occupation time of a handoff call.
tcin: the channel occupation time of a new call
which is either forced to terminate due to an
interruption at cell 0 or is handed off to the nextcell during the interruption period.
tcih: the channel occupation time of a handoff callwhich is disconnected due to the interruption.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 32/82
32
Analytic Model for RES 1: Derivationfor Pnc
Consider an observation period, the Pnc isderived as follows.
For a homogeneous cell structure (thehandoff rate entering the cell is equal to thehandoff rate leaving the cell), we obtain
λh =λo(1-Pb)Ph,1+λh (1-Pb)Ph,2
2,1,
2,1,
)1()1(
)1()1(
ib
o
h
ibb
o
h
b
hiboibhbob
nc
PPPPPP
t o
t PPt PP
t o
t Pt PP
−+−++=
∆
∆−+∆−+
∆
∆+∆=
λ
λ
λ
λ
λ
λ λ
λ
λ λ
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 33/82
33
Results: the Effects ofμz
µ z (unit: µx)(α = 0.2; η = 0.7 µx; µy = 10 µx;λo = 2 µx)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 34/82
34
Results: the Effects of λo
λo (unit: µx)(α=0.2; η= 0.7µx; µy=10 µx; µz=1.0 µx)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 35/82
35
Results: the Effects of η
(λo = 2 µx ; α = 0.2; µy = 10 µx; µz=1.0 µx)η (unit: µx)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 36/82
36
Results: the Effects ofμy
µy (unit: µx)(λo = 2 µx ; η = 0.7 µx; α = 0.2; µz=1.0 µx)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 37/82
37
Summary of Research 1
Improving GSM Call Completion by Call Re-Establishment
Call re-establishment significantly reduces
the call incompletion probability for the
interrupted calls.
In most cases, both RES 1 and RES 2 have
the same performance, and RES 3 maysignificantly outperform RES 1 and RES 2,
especially for small call arrival rate λo andlarger mobility rate η .
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 38/82
38
Research 2:Channel Assignment for GSMHalf-Rate and Full-Rate Traffic
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 39/82
39
GSM Half-Rate and Full-Rate Traffic
GSM supports full-rate calls and half-rate calls.
A full-rate call uses one time slot in every frame,
while a half-rate call uses one time slot in everytwo frames.
By introducing the half-rate call, the capacity ofGSM increases.
Mixing full- and half-rate calls in a frequencycarrier results in eight full-rate calls, 16 half-ratecalls, or any feasible combinations.
Once an MS initiates a full-rate (half-rate) callrequest, the MS will operate in full-rate (half-rate)mode until the call is terminated.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 40/82
40
An Example for Full- and Half-RateTraffic
Frame 1
Time Slot Number
0 1 2 3 4 5 6 7
H 1 F 2 H 2 F 3F 1
Time slot 0 in frame 2
is vacant
Frame 2
Time slot 3 is used by
Half #2 and 3
Half #4 uses time slot 6
in frame 2
F 2 H 3 F 3 H 4F 1
empty time slot
F x the time slot is occupied by full-rate call x
H y the time slot is occupied by half-rate call y
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 41/82
41
Channel Assignment Schemes [3]
Random: All full-rate and half-rate calls are
assigned to any free time slots without anycontrol.
Best-Fit: Each incoming full-rate call is
allocated an empty full time slot. A half-rate call
is always assigned a partially occupied time
slot that has already contained a half-rate call.If no such time slot exists, then an empty full
time slot is assigned to the half-rate call. Note
that when a half-rate call departs, it is possible
that more than one partially time slots exist.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 42/82
42
Channel Assignment Schemes (Cont.)
Repacking: This scheme is similar to the best-fit scheme except that when a full-rate call
arrives to a cell, the scheme repacks the half-rate calls if two partially occupied time slots
exist. Repacking is achieved by intracellhandoff technology.
Fair-Repacking: This scheme is a variation of
the repacking scheme. The only difference
between repacking and fair-repacking is that in
fair-repacking, if only one half time slot is left ina cell, the next incoming half-rate call will be
blocked.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 43/82
43
Performance Evaluation: OutputMeasures
The simulation models (for the four schemes), and the analytic
model (for repacking) are proposed.
Pf,f (Pf,h): the force-termination probability for the full-rate (half-rate)
call
Pb,f (Pb,h): the new call blocking probability for a full-rate (half-rate)
call
Pnc,f (Pnc,h): the probability that a full-rate (half-rate) call is not
completed (i.e., either blocked or forced to terminate)
Pnc = (λfPnc,f+λhPnc,h)/(λf+λh): the probability that a full-rate or
half-rate call is not completed
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 44/82
44
Performance Evaluation: InputParameters
λf (λh): the new full-rate (half-rate) callarrival rate to a cell
1/ μf (1/ μh): the expected full-rate (half-rate)
call holding time
ηf (ηh): the full-rate (half-rate) MS mobility
rate
c: total number of time slots in a cell
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 45/82
45
Analytic Model for Repacking :TimingDiagram
t mi,0 t mi,1 t mi,j-1 t mi,j
τ mi,0 t ci,j
t ci,j-1
t ci type i call arrival type i call completion
time
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 46/82
46
Analytical Model for Repacking:Derivation forλh,i,ρi, and Pnc,i
From [4],λh,i,ρi, and pnc,i (for i = f or h) can
be expressed as
)]()1(1[
)](1[)1(*
,
*
,
,
imii f i
iimiiib
ih f p
f p
µ µ
λ µ η λ
−−
−−=
−−−
−=)]()1(1[
)](1[1
*
,
*
imii f i
imii
i
ii
f p
f
µ µ
µ η
µ
λ ρ
i f
imii f i
imiiibibinc p
f p f p p p ,*
,
*
,,,
)]()1(1[)](1[)1(
−− −−+=µ µ µ η
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 47/82
47
Analytic Model for Repacking: Derivationfor Pb,i (1/2)
A stochastic process with state n=(nh,nf) is used toderive the new call blocking probability pb,i (i=f or h).
The state space S of the processS={(nh,nf)|nh+2nf≦2c, 0≦nh≦2c, and 0≦nf≦c}
According to Zachary and Kelly, the stationary
probability of n is
where G is
)!
)(!
()( 1
h
n
h
f
n
f
nnGn p
h f
ρ ρ −=
])!
)(!
[(∑∈=sn h
n
h
f
n
f
nnG
h f
ρ ρ
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 48/82
48
Analytic Model for Repacking: Derivationfor Pb,i (2/2)
Pb,f is , where
E1 = {(nh,nf)|nh+2nf=2c or nh+2nf=2c-1,
0≦nh≦2c, 0≦nf≦c}
Pb,h is , where
E2 = {(nh,nf)|nh+2nf=2c, 0≦nh≦2c, 0≦nf≦c}
∑∈
=1
, )( E n
f b n p p
∑∈
=2
, )( E n
hb n p p
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 49/82
49
The Iterative Algorithm
Step 1. Select initial values for λh,h andλh,f.
Step 2. Compute pb,f
and pb,h
.
Step 3. λh,f,old←λh,f andλh,h,old←λh,h.
Step 4. Computeλh,f andλh,h.
Step 5. Ifλh,f andλh,h converges then go toStep 6, otherwise, go to Step 2.
Step 6. Compute pnc,f, pnc,h.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 50/82
50
Results: Effects of the Proportionofλf
λf/(λf+λh)(a)ηf=ηh=2μf
λf/(λ
f+λ
h)(b)ηf=ηh=0.1μf
(c=7,λf+λh=4μf ,μh=μf)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 51/82
51
Results: Effects of Incoming CallTraffic
λf (unit:μf)
(a)λ
f
(unit:μf
)
(b)
(c=7,ηf=ηh=2μf ,μh=μf ,λh=λf)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 52/82
52
Results: Effects of MS Mobilityηf
andηh
λf (unit:μf)(a)
λf (unit:μf)(b)
(c=7,ηf=2μf ,μh=μf ,λh=λf)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 53/82
53
Results: Effects of MS Mobilityηf
andηh (Cont.)
λf (unit:μf)
(a)
λf (unit:μf)
(b)
(c=7,ηh=2μf ,μh=μf ,λh=λf)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 54/82
54
Results: Effects of c
λf (unit:μf)
(c=21,ηf=ηh=0.1μf ,μh=μf ,λh=λf)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 55/82
55
Summary of Research 2
The repacking scheme can significantlyimprove the p
ncperformance over the other
three schemes (about 20% improvements)
pnc increases when the proportion of full-rate
call traffic increases.
Changingηf (ηh) has significant effect on
pnc,f (pnc,h), and only insignificant effect onpnc,h (pnc,f) in the repacking scheme.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 56/82
56
Research 3:Channel Allocation for GPRS
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 57/82
57
Channel Allocation for GPRS
Based on the GSM radio architecture, GPRSshares the radio resources with GSM voice
users to provide users data connections withvariable data rates and high bandwidthefficiency.
In GPRS service, allocation of physical channelsis flexible (i.e., multiple channels can beallocated to a user).
In this research, we will propose four algorithms
for the GPRS users and GSM voice users.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 58/82
58
GPRS Architecture
: Signalling and Data Transfer Interface
: Signalling Interface
MSExternal Data
Network
Other GPRS Network
MSC/VLR HLR
SGSN GGSN
GGSNSGSN
BSS
MS: Mobile Station
BSS: Base Station SubsystemMSC: Mobile Switching Center
HLR: Home Location Register
VLR: Vistor Location Register
SGSN: Serving GPRS
Support Node
GGSN: Gateway GPRS
Support Node
在GPRS架構中
MS, BSS, VLR以及 HLR均作了一些修改.
例如: HLR新增存放 GPRS User資訊的功能.
另外新增了SGSN與 GGSN兩種 GSN
SGSN負責將 Packet Data Route至MS端.
GGSN做為GPRS與其它Data Network 連結的Gateway.
GPRS網路中用 GPRS Tunnel Protocol (GTP)來
Tunnel User Data以及 signaling message.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 59/82
59
GPRS Uplink Packet Transfer
MS Network
Data Block Transmission on PDTCH
Step 2.
Step 3. Resource Request on PDTCH
Step 4. Packet Resource Re-assignment on PDCCH
Step 5. Packet Resource Re-assignment Ack on PDCCH
Data Block Transmission on PDTCH
Step 7. Last Data Block Transmission on PDTCH
Step 8. Final Block Ack/Nack
Data Block Transmission on PDTCH
Access and Assignment (PCCCH/PDCCH)Step 1.
Data Block Transmission on PDTCHStep 6.
此張圖介紹了 GPRS Uplink Packet Transfer的Message Flow.
At Step 4, the amount of PDCHs for the request will be recorded in the QoS
Profile of the user at SGSN.
注意:在 Step 1與 Step 4中有兩種 Allocate Radio Resource給MS的方式.
一為 fixed resource allocation另一為 dynamic resource allocation.這亦是我們要研究的點.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 60/82
60
Four Resource AllocationAlgorithms
Fixed Resource Allocation (FRA)
Dynamic Resource Allocation (DRA)
Fixed Resource Allocation with Queuecapability (FRAQ)
Dynamic Resource Allocation with Queue
capability (DRAQ)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 61/82
61
Assumptions for Allocation Algorithms
A GPRS data request specifies K channels fortransmission.
The packets are transmitted at rate μp if singlechannel is assigned to a GPRS request.Consequently, if k channels are assigned to aGPRS data request, then this packet requestwill be delivered with rate kμp .
There are L free channels at a cell when aGPRS data request or a GSM voice call request
arrives.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 62/82
62
Fixed Resource Allocation (FRA)
FRA: For a data request of K channels, theBS assigns K channels to the GPRS packet
request if K<=L. Otherwise, the GPRS packetrequest is rejected.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 63/82
63
Dynamic Resource Allocation (DRA)
DRA: For a data request of K channels, DRAallocates at most K channels to the request. If
L>=K then K channels are allocated to therequest. If 0<L<K then L channels areallocated to the request. If L=0 then therequest is rejected.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 64/82
64
Fixed Resource Allocation withQueue capability (FRAQ) (1/2)
FRAQ handles GPRS data requests in thesame way as FRA. For GSM voice call
requests, FRAQ provides a queue to hold GSMvoice call requests when all channels are busy.
These queued GSM requests are served
immediately when idle channels are available.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 65/82
65
Fixed Resource Allocation withQueue capability (FRAQ) (2/2)
FRAQ may selectively queue new calls only,the handoff calls only, or both new and handoff
calls, and the corresponding mechanisms areFRAQ_N (for new call only), FRAQ_H (for
handoff calls only), and FRAQ_NH (for both
new calls and handoff calls)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 66/82
66
Dynamic Resource Allocation withQueue capability (DRAQ)
DRAQ assigns channels to a GPRS data
request in the same way as DRA and assignschannels to GSM voice call requests in the
same way as FRAQ.
There are three DRAQ variations: DRAQ_N
(for new calls only), DRAQ_H (for handoff
calls only), and DRAQ_NH (for both new callsand handoff calls).
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 67/82
67
Performance Evaluation: OutputMeasures
The simulation models (for the eight schemes) andanalytic models (for FRA, DRA, FRAQ) are proposed.
In the models, we consider the mobility of voice usersbut ignore the effect of mobility on GPRS packettransmission.
Pbp (Pbv): the blocking probability for the GPRS packet(the new call blocking probability for the GSM voice call)
Pncv: the probability that a GSM voice call is notcompleted (either blocked or forced to terminate).
cp: the average number of channels for a served packet
Wavg: the average waiting time for the accepted voicecall requests
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 68/82
68
Performance Evaluation: InputParameters
ηv: the GSM voice user mobility rate
λp
(λv): the GPRS packet arrival rate to a
cell (the new GSM voice call arrival rate to acell)
1/ μp (1/ μv): the expected GPRS packettransmission time if one channel is used toserve the packet (the expected GSM voicecall holding time)
C: the number of channels in a cell
Q: the maximum number of voice callrequests buffered in the queue.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 69/82
69
Analytic Model for DRA (1/3)
DRA is modeled by a (K+1)-state Markov process.
State (nv, npK, npK-1, npK-2, …, np1) denotes that a cell
is occupied by nv voice users, npk GPRS packets(each allocated K channels), …, and np1 GPRSpackets (each allocated 1 channel).
For the illustration purpose, we consider K=3. Thus, astate is represented by (i,j,k,l), where i=nv, j=np3,k=np2, l=np1.
State space
}0,2 / 0,3 / 0
,0,230|),,,{(
C land C k C j
C iC lk jilk jiS DRA
≤≤≤≤≤≤
≤≤≤+++≤=
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 70/82
70
Analytic Model for DRA (2/3)
Letπi,j,k,l be the steady probability for state
(i,j,k,l).πi,j,k,l
=0 if state (i,j,k,l) not in SDRA
.
Let E1 be the set of the states where no free
channel is available
1),,,(
,,, =∑∈ DRASlk ji
lk jiπ
}0,2 / 0,3 / 0
,0,230|),,,{(1
C land C k C j
C iC lk jilk ji E
≤≤≤≤≤≤
≤≤=+++≤=
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 71/82
71
State Transition Diagram for DRA
i, j, k, l
i-1, j, k, l
v
i, j-1, k, l i, j, k-1, l
i, j, k, l-1
i+1, j, k, l
i, j+1, k, l i, j, k+1, l
i, j, k, l+1 (i+1) М v
3( j+1) µ p 2(k+1) µ p
δ+ Λv
i М v
3jµ p 2kµ p δ3 λ p δ2 λ p
lµ p
δ1 λ p
δ+
3 λ p δ+
2 λ p
δ+
1 λ p
(l+1) µ p
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 72/82
72
Analytic Model for DRA: Derivationfor Pbp, Pbv, Pfv,
and Pncv
The packet requests and voice calls (either
handoff call or new call) are blocked whenthere is no free channel. Thus,
The Pncv can be obtained from the voice call
traffic model as we used in half-rate research.
∑∈
===1),,,(
,,,
E lk ji
lk ji f bb vv pPPP π
fvvm fvv
vmvbv
bvncv p f p
f p
p p
−−
−−
+= )]()1(1[
)](1[)1(
*
*
µ µ
µ η
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 73/82
73
Results: Comparing for the EightResource Allocation Algorithms
(DRAQ_NH;λp=5μv;λv=μv;μp=100μv;
ηv=0.2μv; C=7; Q=7)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 74/82
74
Results: Effects of the Variances ofPacket Transmission Times
(DRAQ_NH;λp=5μv;λv=5μv;μp=100μv;ηv=0.2μv; C=7; Q=7)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 75/82
75
Results: Effects of the Variances ofPacket Inter Arrival Times
(DRAQ_NH;λp=5μv;λv=5μv;μp=100μv;
ηv=0.2μv; C=7; Q=7)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 76/82
76
Results: Effects of the Variances ofGSM Voice User Cell Residence Times
(DRAQ_NH;λp=5μv;λv=5μv;μp=100μv;
ηv=0.2μv; C=7; Q=7)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 77/82
77
Results: The Average Number ofChannels for a Served Packet in
DRAQ_NH (C=7; Q=7)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 78/82
78
Results: The Average Waiting Timefor the Accepted Voice Call Requests
in DRAQ_NH
(λv=μv;μp=100μv;ηv=0.2μv; C=7; Q=7)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 79/82
79
Summary of Research 3
Dynamic allocation effectively increases the
GPRS packet acceptance rate, and thequeuing mechanism significantly reduces the
voice call incompletion probability.
If too many channels are allocated to a
packet transmission, both packet and voice
call droppings will increase.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 80/82
80
Conclusions and Contributions
Our study provided guidelines radio resource
allocation for the different type of trafficgenerated by GSM new services.
• Interrupted Call Traffic
• Half-Rate Voice Call Traffic
• GPRS Packet Data Traffic
We proposed channel allocation schemes,analytic models, and simulation models.
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 81/82
81
Future Work
OVSF Code Channel Assignment for IMT-
2000.
Channel Allocation for Opportunity DrivenMultiple Access (ODMA)
8/8/2019 21 Radio Resource Management
http://slidepdf.com/reader/full/21-radio-resource-management 82/82
82
Publication Lists
Journal Papers
1. Lin, Phone and Lin, Yi-Bing, Channel Allocation for GPRS Packet Data. Accepted and to appear in IEEE Trans. on Vehicular Technology, 2001.
2. Pang, Ai-Chun, Lin, Phone and Lin, Yi-Bing, Modeling Mis-routing Calls Due to User Mobility in Wireless VoIP. Accepted and toappear in IEEE Communications Letter , 2000.
3. Lin, Yi-Bing, Lin, Phone and Chuang, Yu-Min, Modeling CDPD Channel Holding Times. Accepted and to appear in IEICE Trans. onCommunications , E83-B(9):2051-2055, (Sep. 2000).
4. Lin, Phone and Lin, Yi-Bing, Channel Assignment For GSM Half-Rate and Full-Rate Traffic. Computer Communications, 23 (2000):476-482.
5. Lin, Phone, Lin, Yi-Bing and Jeng, J.-Y., Improving GSM Call Completion by Call Re-Establishment. IEEE Journal on Selected Areas inCommunications , 17(7): 1305-1317 (July 1999).
6. Lin, Yi-Bing and Lin, Phone, Performance Modeling of Location Tracking Systems. ACM Mobile Computing and Communications Review , 2(3):24-27 (July-Aug 1998).
Conference Papers
1. Cheng, Ray-Gung and Lin, Phone, OVSF Code Channel Assignment for IMT-2000. IEEE VTC2000 Tokyo, Pages 2188-2192.
2. Chuang, Yu-Ming, Lin, Phone and Lin, Yi-Bing, Modeling CDPD Channel Holding Times. 1999 National Computer Symposium (2),Pages B-11-B-14.
3. Chen, S.-C. S., Yang, C.-S. and Lin, Phone, Software Radio. 5th Mobile Computing Workshop, 74-80 (March 1999).
4. Chen, S.-C. S., Lin, Phone and Lin, Yi-Bing, IMT-2000. 4th Mobile Computing Workshop, 66-72 (March 1998).
5. Lin, Phone and Tsai, W.-N., A Simulation Study of Multiple-Location Scheme for PCS Mobility Management. 3rd Workshop on MobileComputing, 37-45 (March 1997).
Submitted Papers
1. Lin, Phone and Lin, Yi-Bing, Implementation and Performance Evaluation for Mobility Management of a Wireless PBX Network. IEEE Journal on Selected Areas in Communications (in revision).
Pending Patents
1. Chen, S.-C. S., Lin, Phone, and Lin, Yi-Bing, A Call Re-establishment Mechanism “RES” for GSM Call Completion (with ITRI/CCL,submitted to R.O.C., USA, and Europe Patent Offices).
2. Cheng, R.-G., Lin, Phone, and Lin, Yi-Bing, Opportunity Driven Multiple Access (with ITRI/CCL, to be submitted to R.O.C. and USAPatent Offices).