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3GPP-RAN Working Group 1 meeting #2 TSGW1#2(99)031Yokohama, Japan 22-25 February 1999
Agenda Item: 5
Source: Golden Bridge Technology, Inc.
Title: Uplink Common Packet Channel Advantages (A WP-CDMAfeature)
Document for: Discussion and Adoption of Uplink Common Packet Channel
Abstract:
This contribution touches on benefits of having the uplink common packetchannel versus the dedicated packet channel approach. We also discuss themethods of operation of the Common Packet Channel. The physical layer and the MACare also discussed in this contribution.
2
WP-CDMA Distinguishing Features
1.Uplink Common Packet Channel (All Rates)• Common Packet Channel will transport all data rates up to
and including 2.048 Mbps.• Constant Power Level Preamble with 16 possible sequences • Closed Loop Power Control, Preamble Ramp-up mechanism• Fast L1 ACK mechanism (within 250 micro-seconds)• Collision Detection with Low Feedback Delay (2 ms)• Downlink Common Power Control Structure
2. Common Control Channel in the Down Link3. Intra-frequency Hard Handover4. Quick Handover5. Structure of the WP-CDMA CCPCH (Common Control Physical Channel)
6. Multi-code Option for Higher Rates• The relationship between the VSF and number of multi-codes is the subject of further study
• TM Common Pilot for coherent demodulation• Adjustable Power SCH1 And SCH2 for faster initial cell search
7. Higher APC Rates8. Removal of Link Maintenance Channel
3
IP Traffic Types And CharacteristicsTable [1-4]
Attribute
IP Packets,WWW
browsingBest Effort
IP Packets,real time
audioInteractive
IP Packets,WWW
browsingPrioritized
IP Packets,WWW
browsingGuaranteed
IP Packets,WWW
browsingReal timestreaming
Direction Bi Bi Bi Bi UniPeak BitRate 2 Mbps 12 kbps 2 Mbps 2 Mbps 128 kbps
GuaranteedBit Rate 0 8 kbps 0 64 kbps 64 kbps
Average BitRate NA 4 kbps NA NA NA
SDU Sizespec (bits) 2 Ko 2 Ko 2 Ko 2 Ko 2 Ko
Max SDULoss Rate 10e-3 5% 10e-3 10e-3 5%
Max SDUerror rate 10e-9 10e-6 10e-9 10e-9 10e-6
Max SDUDelay 30s 80 ms 30s 30s 1s
Allocationpriority NA Dynamic
e.g. medium NA NA NA
Retentionpriority NA Dynamic
e.g. medium NA NA NA
TrafficHandlingpriority
NA NA Dynamice.g. high
Dynamice.g. medium
Dynamice.g. medium
[1] UMTSD 22.05[2] UMTS 22.60[3] TR 22.60[4] Tdoc SMG12 98 S 693
4
What are the Information Transfer and InformationQuality Attributes of These Services?
Information Transfer AttributeConnection Mode Connectionless, Connection-
orientedTraffic type attribute CBR, VBR, ABR, UBRSymmetry attribute Bi, UniInformation transfer rate 12 kbps, 2 MbpsInformation Quality AttributeMaximum transfer delay 80 ms, 1 s, 30 sDelay variationBit Error Rate 10 –6, 10 –9
Error Characteristics Bursty, uniform
5
How can the Common Air Interface be
Optimized for Packet Data Services?
The CAI should be able to support high bit rates (up to 2 Mbps),bursty, asymmetric, non-real time bearer capabilities
The CAI should support the connectionless mode as well as theconnection-oriented modes
The CAI should be able to support packet switching as well ascircuit switching transfer modes
The QoS on demand and flexibility to provision various informationquality attributes per connection (implications on physical layer,the MAC and DLC)
Minimize interworking functionality Maintain the same QoS in the wireline and wireless systems Minimize interference at the air interface Minimize resource requirement at the base station Optimize the IP protocol suite for the air interface Implementation of optimum bandwidth allocation at the air interface
6
WP-CDMA Distinguishing Features
Common Packet Channel (All Rates)
• Common Packet Channel will transport all data rates up to and including 2.0489 Mbps.
• Constant Power Level Preamble with 16 possible sequences
• Closed Loop Power Control, Preamble Ramp-up mechanism
• Fast L1 ACK mechanism (within 250 micro-seconds)
• Collision Detection with Low Feedback Delay (2 ms)
• Downlink Common Control Channel Structure
7
F A BMOB ID F A BMOB
ID F A BMOB ID B
User i+1Packet MUser i
PacketM MUser i + 2
Packet 1User iPacket
E E User i+3Packet 1
EUser i+1Packet
MUser i + 3Packet 1
F = Free A = ACK B = BusyMob ID = Temp ID for Collision DetectionE = EndM = More
CPCHUL
WP-CDMA Common PacketChannel Uplink
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Packet 1 Packet 2 Packet 3 t iUser i
T inactivityPacket 1 Packet 2 t i+1
User i+1T inactivity
ti
Packet 1 t i+2
User i+2T inactivity
Short Term Circuit Assignment
Packet 2 Packet 3 Packet 4
t
Packet 1 Packet 2 Packet 3User n
i+1
nt
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WIMS 76.8 kbps, Uplink Indoor A, Soft Decision Viterbi, R=1/3, K=9 Power Control, ±1 dB @ 1.6 kHz
3.66E-02
1.28E-02
3.97E-03
1.33E-03
4.25E-04
3.33E-01
1.90E-01
1.00E-01
3.25E-02
8.24E-03
1.74E-03
1.81E-04
5.16E-02
1.82E-02
1.09E-02
4.38E-03
1.31E-03
3.50E-04
8.20E-05
3.99E-012.70E-01
1.15E-01
3.09E-02
4.14E-03
4.25E-04
2.56E-023.21E-02
1E-04
1E-03
1E-02
1E-01
1E+00
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Eb/No, dB
BE
R
No APC, No Ant. Diversity
APC, No Ant. Diversity
No APC, Ant. Diversity
APC, Ant. Diversity
1.73E-03
Closed Loop Power ControlCourtesy of AT&T Labs
10
3.416
1.419
Ri 19
Ri 10
Ri 1
13.251.25 li8
0 2 4 6 8 10 12 141
1.5
2
2.5
3
3.5
Packet Length in Kbyte
Capacity RatioP-S/C-S
Channel inactivity = 50 ms
Channel inactivity = 500 ms
Channel inactivity = 1 s
Advantages of Statistical Multiplexing
144 kbpsCapacity Ratio Versus Packet Length in Kbyte
PB=2%100% Duty Cycle
11
384 KbpsCapacity Ratio Versus Packet Length in Kbyte
PB=2%100% Duty Cycle
8.176
2.85
Ri 19
Ri 10
Ri 1
272.5 li8
0 5 10 15 20 25 302
3
4
5
6
7
8
9
Packet Length in Kbyte
Capacity RatioP-S/C-S Channel inactivity time = 1 s
Channel inactivity time = 500 ms
Channel inactivity time = 50 ms
Advantages of Statistical Multiplexing
12
2048 KbpsCapacity Ratio Versus Packet Length in Kbyte
PB=2%100% Duty Cycle
42.84
7.427
Ri 19
Ri 10
R i 1
425 l i
8
5 10 15 20 25 30 35 40 455
10
15
20
25
30
35
40
45
Channel inactivity time = 1 sChannel inactivity time = 500 ms
Channel inactivity time = 50 ms
Packet Length in Kbyte
Capacity RatioP-S/C-S
Advantages of Statistical Multiplexing
13
1 ms .25 ms
I
Q
Data/ControlPreambleramp-up
N x TBD ms
UL-CPCH Burst Structure
14
.625 ms, 10 x 2k bits (k=0,….6)
N data bit 1Data
N data bit 1Data
PilotN pilot bits
PilotN pilot bits
TPCNTPC bits
TPCNTPC bits
RINRI bits
RINRIbits
CD bitsNCD
UL-CPCH
UL-CPCH
UL-CPCH
UL-CPCH
I
Q
I
Q
Slots 0
Slots 1
UL-CPCH Slot Structure
15
.625 ms, 10 x 2k bits (k=0,….6)
N data bit 1Data
PilotN pilot bits
TPCNTPC bits
RINRI bits
UL-CPCH
UL-CPCH
I
Q
Slot #1 Slot #2 Slot #i Slot #16
Tf = 10 ms
UL-CPCH Frame Structure
16
Data
Power Control
N x TBD ms
1 ms .25 ms
DL-CCCH
UL-CPCH
CCCH: Common Control ChannelCPCH: Common Packet Channel
L1ACK
TBD ProcedureBased
Overall Protocol Operation
17
DL-CCCH
pd TT
BS F 0 1 2 3 4 5 6 7
2.5 ms 8 mini-slots
ACK CD
CD
TBD
F
1.875 ms
1ms 250 s Slot 0625 s
BS
MSUL-CPCH
Collision Feedback Delay Cycle
18
Overall Protocol Operation
DL CCCHACK/NAK
1.25 ms
LIACK
UL CPCHCD CD
CDCD PC ARQ
19
Collision Probability
Pc= P c 2 P(2,T) + P c 3 P(3,T)+ P c 4 P(4,T) + P c 5P(5,T)+ …
Where:
T = Tp+Tcc
Tcc = contention cycleTp = Packet length
P c m Nm / Ms
Ms = Ns x Nc
Ns = number of mini-slotsNc = Number of available signature codesNm = m / {2x(m-2))}
20
Throughput Delay Analysis with Re-transmissions dueto Collision and Errors and Congestion Control
Throughput Delay of an M./M/1 queue with the congestion control [1]
E [ T] = 1/(1- e -) = (1- e -)
E [n] =
Collisions Re-transmissions due to errors Congestion Control
= (1- e -)(1-Pc) / NARQE [ T] = NARQ /{(1- e -)(1-Pc)}
[1] Mischa Schwartz, “Computer Communications Networks”
21
Throughput Performance of DSMAImpact of Low Collision Feedback Delay
22
Performance Advantages of UplinkCommon Packet Channel
(Summary-1)
Proven improved throughput performance for short bursty traffic and high peak rate
•Sample pt: 384 kbps, L=4 Kbyte, Access overhead =500 ms, P B = 2% Throughput improvement Ratio = 5
•UDD Services
Improved delay performance of M/M/1 (packet switched) overM/M/n (circuit switched) for longer packets
Common Packet Channel approach requires an order of magnitudeless BS resources (modems) as compared to Short Term CircuitAssignment.
• M/M/10 requires 10 times more modems in the BS as compared to M/M/1
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• Statistical multiplexing advantages for bursty traffic
• Less delay M/M/1 versus M/M/n
• Resource minimization and less hardware complexity
• Facilitation of higher peak rates
Performance Advantagesof CPCH-UL
• Queuing time & transmission time
• Limitations of circuit switching trunking efficiency
(Summary-2)
• Optimum prioritization scheme
• Optimum bandwidth allocation in a mixed circuit-switched/packet switched air interface operation in short time window (frame by frame basis)