UoS Performance Evaluation and Optimisation of the European...
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Performance Evaluation and Optimisation for DVB/DAVIC UoS 1/50 UNAM Dr. Victor Rangel Centre for Mobile Communications Research EEE Department, University of Sheffield Sponsored by:The National Autonomous University of Mexico (UNAM) Sponsored by:The National Autonomous University of Mexico (UNAM) and NORTEL NETWORKS and NORTEL NETWORKS Performance Evaluation and Optimisation of the European Cable Modem Television Protocol: DVB/DAVIC March 4, 2003 March 4, 2003
Transcript of UoS Performance Evaluation and Optimisation of the European...
Perfo
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1/50UNAM
Dr. Victor RangelCentre for Mobile Communications Research
EEE Department, University of Sheffield
Sponsored by:The National Autonomous University of Mexico (UNAM)Sponsored by:The National Autonomous University of Mexico (UNAM)and NORTEL NETWORKSand NORTEL NETWORKS
Performance Evaluation and Optimisation ofthe European Cable Modem
Television Protocol: DVB/DAVIC
March 4, 2003March 4, 2003
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Presentation outline
? CATV Network Arquitecture
? DVB/DAVIC Reference Model
? DVB/DAVIC Characteristics and MAC Operation
? Performance Optimisation using Contention Resolution Algorithms
? Performance Optimization Using Enhanced Reservation Request Mechanisms
? Performance Optimisation using Contention Slot Allocators
? Performance Analysis of Voice over IP
? Future Work
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CATV Architecture
FibreDomain
CoaxialDomain
Satellite dish
HEADEND (INA)
o/e converter Amplifier
EuroModemSet-Top-Box
Home drop
Splitter
Internet
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DVB/DAVIC Reference Model
EndUser
BroadcastDeliveryMedia
BC
InteractionNetwork
Interactive Channels
Broadcast Channel
Interactive Channel
NIU
STU
BIM
IIM
Set Top Box (STB)/EuroModemBroadcast
ServiceProvider
BroadcastNetworkAdaptor
InteractiveServiceProvider
InteractiveNetworkAdaptor
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DVB/DAVIC Characteristics
? Also known as ETSI ES 200 800 or ETS 300 800
? Upstream Frequency Range: 5-65MHz
? Downstream Frequency Range : 70-130MHz, 300-862MHz
? Upstream Rate: 0.256, 1.5, 3, 6 and 12 Mbps
? Downstream Rate: 41Mbps(64-QAM), 52Mbps(256-QAM)
? Access Modes: Contention, Reservation & Fixed-rate
? CRA: Exponential Backoff & Splitting Tree Algorithm
? 1-Downstream Ch. can support up to 8 Upstream Ch.
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DVB/DAVIC Packet Formats
? Upstream
4 1653ATM Cell RS GBUW
64-byte Upstream Slot Format
8 7 6 5 4 3 2 1
VCI
GFC VPIVPI
PTHEC
CLP
bits
Payload AreaATMHeader
User Data
DVB-MAC Message
5 48
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DVB/DAVIC Packet Formats
? Upstream
4 1653ATM Cell RS GBUW
64-byte Upstream Slot Format
163 1 1
Minislot
1
Minislot Minislot GB
21 21 21
MAC Info.Element
UW SFPayload Area
GBMssg. Conf.Type
MACAddress
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DVB/DAVIC Packet Formats
? Downstream : User Data188-bytes MPEG2 TS Frame Structure
MPEGHeader Payload Area (ETS 301 192)
1844
188-bytes MPEG2 TS Frame Structure
MPEGHeader
MAC Control Information (MCI)(or signaling information)
MACMessage Rsrv.MAC
MessageMAC
Message
60 40 40 404 4
UpstreamMarker
MACFlags
Ext.Flags
SlotNumber
3 262 3 26
MAC FlagControl
? Downstream: DVB MAC Messages
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DVB MAC Operation - Reservation AccessHeadend (INA) EuroModem (NIU)
Rsv. ID
Packet Arrival.MPEG2 (MCI)
Rsv. Request Time until Cont. Slot
MPEG2 (MCI&Grant)
Data Slot 1.Data Slot 2.Data Slot n
Time until REQ is Succ.And Granted
Packet Transmission
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DVB MAC - Exponential Backoff Alg.
Collision?
End
Pk ArrivalStart Contention
Process
Successful Req.TxWait for grant and then
transmit Data Slots
i = Initial backoff exp.t = truncated backof exp.
i = i + 1, until i <= tb = RND(2 i )
Tx. Req. in a RND CS
backoff (b-1) CS &Tx. Req. In the bth CS
YES
NO
CS = Cntention SlotReq = RequestTx = TransmitRND = Random
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DVB MAC - Splitting Tree Algorithm
Do If (Entry_Stack = 0) wait for group of MS with ACN = 0
Else wait for group of MS R = RND(Entry_Spreading) Until R < 3 Transmit request in minislot number R
FCN ?
<0xFE Collision
=0xFESucc. Tx
Exit
=0xFFError/empty slot
Pk ArrivalStart Contention Process
ACN = Allocation Collison Number
MS = MiniSlot
FCN = Feedback Collison Numberwait for FBCK & Rsv Grant
wait for group of MS with ACN = FCN Tx. Req in MS number RDN(3)
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DVB MAC - Splitting Tree AlgorithmEntry Spreading (Es) Factor = 6
ACN=0
R = RND[1,ES] = 2
R<= 3, ? Tx in CS = 3,MS = 2
Entry Stack = 0
ACN =3
Do If (Entry_Stack = 0) wait for group of MS with ACN = 0
Else wait for group of MS R = RND(Entry_Spreading) Until R < 3 Transmit request in minislot number R
FCN ?
<0xFE Collision
=0xFESucc. Tx
Exit
=0xFFError/empty slot
Pk ArrivalStart Contention Process
wait for FBCK & Rsv Grant
wait for group of MS with ACN = FCN Tx. Req in MS number RDN(3)
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Performance Optimization
using
Contention Resolution Algorithms
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Simulation Parameters
Parameter ValueUpstream data rate 6 MbpsDownstream rate (in-band) 42 MbpsMin. and Max. backoff values [2–10]
Entry spreading values [5-15]
Minimum contention-based slots persignaling frame
3 slots
signaling frame cycle 3 ms
Simulation time for each run 60 sNumber of Stations 10-310
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? Internet TrafficIEEE 802.14 WGPacket Distribution ->64 Kbps
? VoIP Traffic ITU-T H.323 Codec: G.723 Frame size: 30 ms (20 Bytes)Frames per packet: 4 Data rate: 5.3 Kbps (9.6 Kbps with overhead)
? Mixed Traffic Internet Traffic - 22.4 KbpsVoIP Traffic - 9.6 Kbps (5.3 Kbps without overhead)
Message size (bytes)
Prob
abili
ty
64
0.6
0.060.04 0.02
0.250.03
124 256 512 1024 1518
Traffic Characteristics
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Exponential Backoff Algorithm Performance
Inte
rnet
Tra
ffic
(64
Kbp
s)
0150300450600750900
1050
38 40 42 44 46 48 50 52Number of Active Stations
Mea
n Ac
cess
Del
ay
(ms)
W(5-6)
W(3-5)
W(7-9)
W(2-4)
W(8-10)
0.380.400.420.440.460.480.500.52
38 40 42 44 46 48 50 52
Number of Active Stations
Syst
em T
hrou
ghpu
t (N
orm
alis
ed)
W(2-4)
W(8-10)
W(5-6)W(3-5)
W(7-9)
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Splitting Tree Algorithm Performance
VoI
P T
raff
ic (9
.6 K
bps)
050
100150200250300350400450500
275 280 285 290 295 300 305
Number of Active Stations
Mea
n Ac
cess
Del
ay
(ms) Es-14
Es-5
Es-6
Es-8
0.4280.4320.4360.4400.4440.4480.4520.456
280 285 290 295 300 305
Number of Active Stations
Syst
em T
hrou
ghpu
t (N
orm
alis
ed)
Es-5Es-6
Es-8Es-14
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Performance Comparison: Exp. Backoff Vs Split. Tree Alg.
VoI
P, I
P &
Mix
ed T
raff
ic
0100200300400500600700800900
1000
0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65Normalised Offered Load
Mea
n Ac
cess
Del
ay
(ms)
Bck-VoIP
Bck-IP
Bck-Mixed
Tree-VoIP
Tree-Mixed
Tree-IP
0.250.300.350.400.450.500.550.600.65
0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7
Normalised Offered Load
Syst
em T
hrou
ghpu
t (N
orm
alis
ed)
Tree-IPTree-Mixed
Bck-IP
Bck-VoIP
Bck-Mixed
Tree-VoIP
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Resume
? Optimized Backoff Windows for the EBA: For IP Traffic: W[5-6], W[5-7], W[5,8] => Max. Thrg. = 50% cc
For VoIP: W[5-7], W[5-8], W[6-8], W[5-9] => Max. Thrg. = 32%
? Optimized Entry Spreading factor for the STA:
For IP Traffic: Entry Spreading = 8 & 14 => Max. Thrg. = 60%
For VoIP: Entry Spreading = 8, 10 & 14 => Max. Thrg. = 45%
? Increased performance for the STA of appr. 10-13 % over the EBA.
(The use of minislot, feedback and allocation info. reduce the
risk of collision considerably)
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Performance Optimization
using
Enhanced Reservation Request Mechanism
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Enhanced Mechanisms: - Reserved Request (RR)
Headend (INA) EuroModem (NIU)
Rsv. ID
Data Block (50-Slots)MPEG2 (MCI)
Time until REQ is Successful and Granted
MPEG2 (MCI&Grant)
Data Slot 1Data Block TX
Data Slot 32
RR-Slot 33 Reserved Req. (18-Slots)
Time until CS or MS
RR Reserved Req. (33-Slots)Max Rsv. Req. [1-256], set to 32
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Enhanced Mechanisms: - Reserved Request (RR)
Headend (INA) EuroModem (NIU)
Rsv. ID
Data Block (10-Slots)MPEG2 (MCI)
Time until REQ is Successful and Granted
MPEG2 (MCI&Grant)
Time until CS or MS
RR Reserved Req. (10-Slots)
Data Slot 1Data Block TX
Data Slot 10
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Enhanced Mechanisms: Continuous Reserved Request (CRR)
Headend (INA) EuroModem (NIU)
Rsv. ID
Data Block (20-Slots)MPEG2 (MCI)
Time until REQ is Successful and Granted
MPEG2 (MCI&Grant)
CRR
Time until CS or MS
Continuous RR(21-Slots)
Data Slot 1Data Block TX
Data Slot 20
Continuous RR (1-Slots)CRR-Slot 21
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Enhanced Mechanisms: Piggyback Request (PG)
Information PayloadATMHeader
Data Slot
UW RS GB
8 7 6 5 4 3 2 1
VCIVPI
PTHEC
CLP
bitsVPIGFC
PiggybackRequest
Pg Value 1 (0-slots )Pg Value 2 (e.g. 3-slots)Pg Value 3 (e.g. 6-slots)Pg Value 4 (e.g. 12-slots)
00 -01 -10 -11 -
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Enhanced Mechanisms: Piggyback Request (PG)
Headend (INA) EuroModem (NIU)
Rsv. ID
Data Block (50-Slots)MPEG2 (MCI)
Time until REQ is Successful and Granted
MPEG2 (MCI&Grant)
PRA
Time until CS or MS
Reservation Req. (32-Slots)
Data Slot 1
Data Block TXData Slot 2
Data Slot (PG:12-Slots)Data Slot 32 + PG
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Enhanced Mechanisms: Continuous Piggyback Req.. (CPG)
Information PayloadATMHeader
Data Slot
UW RS GB
8 7 6 5 4 3 2 1
VCIVPI
PTHEC
CLP
bitsVPIGFC
ContinuousPiggybackRequest
Pg Value 1 (0-slots )Pg Value 2 (1-slots)Pg Value 3 (e.g. 6-slots)Pg Value 4 (e.g. 12-slots)
00 -01 -10 -11 -
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Enhanced Mechanisms: Continuous Piggyback Req. (CPG)
Headend (INA) EuroModem (NIU)
Rsv. ID
Data Block (20-Slots)MPEG2 (MCI)
Time until REQ is Successful and Granted
MPEG2 (MCI&Grant)
PRA
Time until CS or MS
Reservation Req. (20-Slots)
Data Slot 1
Data Block TXData Slot 2
Data Slot (CPG:1-Slots)Data Slot 20 + CPG
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Enhanced Mechanisms: Unsolicited Grant Slot (UGS)
Headend (INA) EuroModem (NIU)
Rsv. ID
Data Block (4-Slots,120ms)
Resource Req.Time until CS or MS
Resource Request- New cyclic assignment needed- Requested bandwidth- Max. distance between slots
MPEG2 (Connect Message&Grant) New cyclic assignment granted
Data Slot 1 Data Block TXData Slot 4
Data Block (4-Slots)
Data Slot 1 Data Block TXData Slot 4
MPEG2 (Grant)
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Simulation Parameters
Parameter ValueUpstream data rate 3 Mbps
Downstream data rate (64-QAM, In-band) 42 Mbps
Minimum and Maximum Backoff Values 3 and 5
Entry Spreading factor of the Spl. Tree Alg. 6
Min. No. Contention-slots per MCI frame 3 slots
Transmission time of the MCI frame 3 ms
Simulation time for each run 60 s
Distance form the nearest/farthest NIU to the HE 10-16 Km
Propagation delay (coax and fibre) 5 µs/Km
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? VoIP Traffic ITU-T H.323 Codec: G.723 Frame size: 30 ms (20 Bytes)Frames per packet: 4 Data rate: 5.3 Kbps (9.6 Kbps with overhead)
Performance Analysis : Traffic Characteristics
Message size (bytes)
Prob
abili
ty
64
0.6
0.060.04 0.02
0.250.03
124 256 512 1024 1518
? Mixed Traffic (41.6 Kbps)VoIP Traffic (9.6 Kbps)Internet Traffic (32 Kbps) ----> Packet Distribution
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0
30
60
90
120
150
180
210
240
270
300
85 95 105 115 125 135 145 155 165 175Number of NIUs
Mea
n Ac
cess
Del
ay (m
s)
Performance Optimisation? MEAN PACKET ACCESS DELAY: Voice over IP Traffic
PRA
RR
CRR
PG
PRA + mPG+m
CPG
UGS
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0.32
0.34
0.36
0.38
0.40
0.42
0.44
0.46
0.48
0.50
0.52
0.54
105 110 115 120 125 130 135 140 145 150 155 160 165 170 175
Number of NIUs
Nor
mal
ised
Syst
em T
hrou
ghpu
t
Performance Optimisation? SYSTEM THROUGHPUT : Voice over IP Traffic
PRA
RR
CRR
PGPRA + m
PG+mCPG
UGS
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0
30
60
90
120
150
180
210
240
270
300
28 30 32 34 36 38 40 42 44
Number of NIUs
Mea
n Ac
cess
Del
ay (m
s)
Performance Optimisation? MEAN PACKET ACCESS DELAY: Mixed Traffic (9.6Kbps VoIP + 32Kbps IP)
PRARR
CRR
PG
PRA + m
PG+m
CPG
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Resume
? Five enhanced reservation request have been presented.(RR, CRR, PG, CPG and UGS).
? As they become more complex these mechanisms efficientlyreduce, and in some cases avoid, the collision risk of reservationrequest transmissions, increasing markedly the systemperformance.
? The UGS & CPG are more suitable for the delivery of VoIP traffic
? The use of Minislots (Split. Tree Alg.) combined with/without the PG is more suitable for the delivery of Internet orBursty traffic.
? The PG and CPG have already been integrated into the latest version of the DVB/DAVIC standard: ETSI ES 200 800
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Performance Optimization
using
Contention Slot Allocators
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Simple Contention Slot Allocator (Simple-CSA)
? Unused slots are allocated to contention slots
Signalling Frame
S1:R5
S6:R3
S3:R2
INA (HE)
ReservedSlots = 10
s1
s1
s1
s1
s1
s6
s6
s6
s3
s3
18 slots = 3 ms
? In all signalling frames there is always a minimum number of contention slots (CSs)
Signalling Frame
S1:R9
S6:R9
S3:R9
INA (HE)
ReservedSlots = 27
s1
s1
s1
s1
s1
s1
s1
s1
s1
s6
s6
s6
s6
s6
s6
Min. CSs = 3
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Forced Contention Slot Allocator (Forced-CSA)
? For every collision, the Forced CSA adds a flexible number of slots: Forced Slots (FSs)
Signalling FrameINA (HE)
ReservedSlots = 19
s1
s1
s1
s1
s1
s1
s1
s1
s8
s8
s8
s8
Min. CSs (2)
S1:R9
S6:R6
S3:R3
S8:R9s1
Forced. CSs (3)
? Follows the same strategy as the Simple-CSA,as for the Min. CSs and unused slots.
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Variable Contention Slot Allocator (Variable-CSA)
? This mechanism uses a variable slot regime in which the ratio of CSs to ? reservation data slots (RSs) is varied from signalling frame to ? signalling frame
? Follows the same strategy as the Simple-CSA.
RSs
RSs
0 if MAX_REQ (MAX_DATA-N )N else
VCSs?? ??? ?
?
? The number of Variable CSs (VCSs) is based on the current traffic load, ? mean packet size and mean requested slots.
2 _2 Re _RSs
MAX DATAN
q Size? ??? ? ??? ?
NRSs Converts the number of RSs to CSsMAX_DATA Maximum number of data slots that can fit in a signalling frame
(e.g: 18 –Min. CSs) Req_Size Average number of RSs that can be requested at once. MAX_REQ Total number of data slots requested but not yet allocated
? ?? ? design parameter set to 2.5
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Performance Optimisation: ? Simulation Parameters: Same as previous analysis (3 Mbps Up, 42Mbps Dows)? Mixed Traffic (9.6Kbps VoIP + 32Kbps IP)
SYSTEM THROUGHPUT
41.542.042.543.043.544.044.545.045.546.046.5
31 32 33 34 35 36 37 38 39 40
Number of Active Stations
Sys
tem
Th
rou
ghp
ut
(%)
Simple-CSA(CSs-3) Simple-CSA(CSs-5)Forced-CSA(FSs-2,CSs-2) Forced-CSA(FSs-2,CSs-3)Variable-CSA(CSs-2) Variable-CSA(CSs-3)
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Performance Optimisation:
AVERAGE NUMBER OF CONTENTION SLOTS PER REQUEST
2.72.93.13.33.53.73.94.14.34.5
29 30 31 32 33 34 35 36 37 38 39 40
Number of Active Stations
Ave
rage
Num
ber
of
Con
tent
ion
Slot
per
Req
uest
Simple-CSA(CSs-3) Simple-CSA(CSs-5)Forced-CSA(FSs-2,CSs-2) Forced-CSA(FSs-2,CSs-3)Variable-CSA(CSs-2) Variable-CSA(CSs-3)
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Resume
? For the EBA is used, the system performance could be increased by adopting three Contention Slot Allocators
? When the Simple-CSA is selected, the best system performance is obtained when the Min. No. of CSs is 5
? For different traffic configurations, the Forced-CSA outperforms the other two? Contention Slot Alloccators (Simple and Variable)
? For the STA is used, the system performance could be increased whenthe Simple-CSA uses 1 slot as the Min. No. of CSs per signalling frame
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Further Research
destination address
ver.
source address
lengthID number
ToSIHLflags fragmentation offset
TTL protocol header checksum
source port
time stampSSRC
destination portlength header checksum
v sequence
CSRC list
M PTP X CC
IP h
eade
rU
DP
head
erR
TPhe
ader
fixed field variable field
32 - bit
? Header Suppression
? QoS: Voice over IP (G.711, G7.732) Video over IP (H.323
G.711 - 64 Kbps (ISDN) G.723.1 - 5.3 Kbps - HS + HS - HS + HS - HS + HS - HS + HS
Frame Size 10 10 30 30 30 30 120 120 Voice Frame 80 80 240 240 20 20 80 80 RTP [bytes] 12 7 12 7 12 7 12 7 UDP [bytes] 8 2 8 2 8 2 8 2 IP [bytes] 20 4 20 4 20 4 20 4 LLC [bytes] 3 3 3 3 3 3 3 3 SNAP [Bytes] 5 5 5 5 5 5 5 5 Ethernet MAC 18 0 18 0 18 0 18 0 Voice Packet 146 101 306 261 86 41 146 101 Net Data rate 116.8 80.8 81.6 69.6 22.9 10.9 9.7 6.7
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? Scheduling Algorithms (Priority, Other Service Disciplines)
? Piggyback mechanisms for different piggyback values
ATM Header8 7 6 5 4 3 2 1
VCIVPI
PTHEC
CLP
bitsVPIGFC
PiggybackRequest
Pg Value 1Pg Value 2Pg Value 3Pg Value 4
00 -01 -10 -11 -
? DVB/DAVIC Vs. DOCSIS
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Set-Top Box /Cable Modem
CATV
Wireless Modem
Personal Area Network (PAN)
PDA
Further Research
? Personal Area Networks
? Bluthooth: 2.4 GHz, range 10m/100m, 10 Mbps->100m, Typical Speeds 500 kbs
? IEEE 802.11: 2.4 GHz, range 100m/200m, 11/56 Mbps
? HomeRF: 2.4 GHz, range 100m, 1.5 Mbps (DSL), 10 Mbps
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? Using CATV as a Fixed Broadband Wireless Access Networks based on Cable Modem Standards
? F-BWA: 2.4 –40 GHz, TDM/TDMA, 15 Km radius, Modulation QPSK, 16/64 QAM
Symbol Rates: 20 480, 10 240, 5 12, … , 160 ksym/sec
Internet
BWA Modem
Fixed BWA
BWA BTS
BWA
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Conclusions
? Both CRA have been analysed and optimised: STA outperforms EBA
? Five enhanced reservation request mechanism have been presented:RR, CRR, PG, CPG and UGS.
? Three CSA have been presented: The Forced-CSA outperforms the other two mechanisms (Simple and Variable-CSA)
? There is a lot to be done: Work is need for DVB/DAVICQoS, Scheduling algorithms, Heather Suppression/Compression
? Research is needed for the support of PAN and F-BWA
? Publications available in: www.fi-b.unam.mx/pp/profesores/victor/publicaciones
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QuestionsDr. Víctor [email protected]
www.fi-b.unam.mx/pp/profesores/victorTELECOMMUNICATIONS ENGINEERING DEPARTMENT
NATIONAL AUTONOMOUS UNIVERSITY OF MEXICO, (UNAM)
Dr. Rob Edwards [email protected]
CENTRO FOR MOBILE COMMUNICATIONS RESEARCHELECTRICAL AND ELECTRONIC ENGINEERING DEPARTMENT
UNIVERSITY OF SHEFFIELD
Download this presentation in www.fi-b.unam.mx/pp/profesores/victor/SCTE
