004 EVDO Theory (Ind)
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Transcript of 004 EVDO Theory (Ind)
Principle and Implementation of CDMA2000 EVDO SystemCBB_T05_E2
ZTE University
CDMA-BSS Team
Unit 1
3G and Beyond
Goals of Rev A
Increase spectral
efficiency and throughput
Increase peak rates and average
throughput
Support for delay-sensitive
applications
Support for QoS (Quality of Service)
Higher reverse link throughput
Lower latency
Backward compatibility
with Rel 0
1x EVDO Network Structure
A Interfaces of 1xEVDO
� Um interface carries the signals exchanged between AT and AN over the air.
� A8 & A9 interfaces are adopted to carry service data and signaling respectively between BSC and PCF.
� A10 & A11 interfaces are adopted to carry service data and signaling respectively between PCF and PDSN.
� A12 interface carries signaling information of access authentication (only include 3 messages: access request, access accept, and access reject).
� A13 interface exchanges signaling when AT is roaming between source AN and target AN
� RADIUS stands for Remote Authentication Dial In User Service. Provides interface between PDSN and AAA to control access to thedata network.
Comparison of EVDO and 1x Networks
BSCBTS
MSC
PCF PDSN
AN AAA AAA
HLR
MS/AT
AN AAA provides radio access authentication similar to MSC/HLR for CDMA2000 1x data call setup
Network Implementation
Centralized StructureCentralized Structure
Upgrading 1x to DO
� BTS side: add EVDO baseband processing part� - If a new EVDO carrier is added,
� Add EVDO baseband processing part
� Add related radio transmission part� Keep antenna and feeder.
� - If upgrading 1x carrier to EVDO carrier� Add EVDO base band processing part� Keep antenna and feeder
� BSC side: add EVDO processing part, upgrade related software for
EVDO Signaling and increased data service capacity requirement
� PCF Side: add data processing module for the increased in capacity
Unit 2
Protocol Architecture
Application Message routing, RLP, flow control
Stream Multiplex various application streams
Session Establish and configure data sessions
Connection Establish and manage radio connections
Security Provide authentication and encryption
MAC Data rate control and scheduling
Physical Adaptive modulation, coding and spreading
EVDO Principles
Forward Channel Structure
Reverse Channel Structure
Key Techniques
Physical Layer Subtypes
� Physical Layer Subtype 0 � Provides backward compatibility to Rel 0� Supports variable data-rate from 38.4 kbps to 2.4576 Mbps for FL, and 9.6 kbps to 153.6 kbps for RL
� Physical Layer Subtype 1� Supports 9.6, 19.2 or 38.4 kbps transmission on the access data channel for RL
� Physical Layer Subtype 2� Supports variable data-rate from 4.8 kbps to 3.072 Mbps for FL, and 4.8 kbps to 1.8432 Mbps for RL� Supports 9.6, 19.2 or 38.4 kbps transmission on the access data channel for RL
Forward Channel Structure
New to Rev A
Forward Data Time Slot
400 40040096 40064 6464 64 96
Data PilotMAC MAC Data Data PilotMAC MAC Data
9664 64
PilotMAC MAC
9664 64
PilotMAC MAC
Idle Slot
Active Slot
½ slot = 1024 chips ½ slot = 1024 chips
Forward Pilot Channel
� The Pilot channel is transmitted at the full sector power.
� The Pilot channel is sent as 96 chip bursts, each of which is located
at the center of each half slot for easier channel estimation and time
synchronization
Forward MAC Channel
� RA subchannel� Broadcast Reverse Activity Bit to all ATs to indicate the current status of the reverse traffic channel
� RPC subchannel� Sends power control commands to the AT for closed loop power control
� DRCLock subchannel� Transmits reverse link quality indication used by the AT for forward link serving sector selection.
� ARQ subchannel (Subtype 2)� Tells each AT if it’s reverse traffic channel packet is successfully received or not.
MAC Index
MAC Channel (Subtype 0 and 1)
� The RPC and DRCLock sub-channels are time-division multiplexed� RPC is transmitted in DRCLockPeriod – 1 times
� DRCLock is transmitted once every DRCLockPeriod and repeated forDRCLockLength times.
� The RA sub-channel is code division multiplexed with either RPC or
DRCLock sub-channel
MAC Channel (Subtype 2)
� H-ARQ or L-ARQ is timeshared (1:3 slots TDM) with the RPC stream.� H-ARQ bit is used to indicate whether the reception of the subpacket resulted in the correct recreation of the entire packet and is transmitted for every subpacket received except the last subpacket.� L-ARQ bit is used to indicate whether the packet was successfully received and is transmitted only after the last subpacket is received
� P-ARQ is timeshared (1:3 slots TDM) with the DRCLock stream.� P-ARQ bit is sent in response to the correct or incorrect reception of the entire physical layer packet. It is transmitted after the time period corresponding to the maximum number of subpackets is over.
� RA is summed together with the RPC stream and DRCLock stream.
ARQ Early Termination
ARQ for Failed Transmission
Forward Pilot / MAC
PilotAll 0’s
RPC bit for each MAC index i
1 bit / 4 slots (150 bps)
HARQ / LARQ for MAC index i
3 bits / 4 slots
RA bit1 bit / slot
192 chips / slot
256 chips / slot
I
IQ
RPC Gain
ARQ Gain
PARQ for MAC index i
3 bits / 4 slots
DRCLock
600 / DRCLockLength bps1 bit / 4 slots
TDM
ARQ Gain
DRCLock Gain
Bit Repeat
Bit Repeat
RA Bit Gain
TDM
SummerSeq. Rep
x 2
TDM
W0
I for even MAC indexQ for odd MAC index
I for even MAC indexQ for odd MAC index
Wi 128
Wi 128
W2 128
Rev A Key Enhancements
� Transmission Format� Notation to define transmission format and interpret the DRC value to determine the data rate
� The turbo coding rate, modulation type and number of available repetition is specified for each transmission format.
� Multi-user Packet� More than one AT (up to 8) receives data during a 1.67 ms time-slot� Contains one or more Security layer packets destined for one or more ATs and is identified by a multi-user preamble
(<packet length (bits)>, <number of slots>, <preamble length (ch(<packet length (bits)>, <number of slots>, <preamble length (chips)>)ips)>)
Forward Control Channel
� Transmission Formats� (128, 4, 1024) � 19.2 kbps� (256, 4, 1024) � 38.4 kbps� (1024, 16, 1024) � 38.4 kbps� (512, 4, 1024) � 76.8 kbps� (1024, 8, 512) � 76.8 kbps
� Synchronous Capsule (SC).� Broadcast Overhead messages � Page messages
� Sub-Synchronous Capsule (SSC)� Facilitates shorter wake intervals for enhance standby time.
� Asynchronous Capsule (AC) � deliver ACK messages and RLP Control messages� may be sent at any time during which the AN is not sending a synchronous or sub-synchronous capsule.
Forward Control Channel
Forward Traffic Channel
� Supported data rates:� 38.4 to 2457.6 Kbps (Subtype 0 and Subtype 1)� 4.8 to 3072 Kbps (Subtype 2)
� Modulation � QPSK, 8PSK or 16-QAM
� Channel coding rate � 1/3 or 1/5.
� A preamble is attached as the header of each physical
layer packet.
� The transmitted packet = preamble + physical layer
packet
Modulation Parameters (Subtype 2)
(128, 16, 1024) 1/5 QPSK 4.8
(128, 8, 512) 1/5 QPSK 9.6
(128, 4, 1024) 1/5 QPSK 19.2
(128, 4, 256) 1/5 QPSK 19.2
(128, 2, 128) 1/5 QPSK 38.4
(128, 1, 64) 1/5 QPSK 76.8
(256, 16, 1024) 1/5 QPSK 9.6
(256, 8, 512) 1/5 QPSK 19.2
(256, 4, 1024) 1/5 QPSK 38.4
(256, 4, 256) 1/5 QPSK 38.4
(256, 2, 128) 1/5 QPSK 76.8
(256, 1, 64) 1/5 QPSK 153.6
(512, 16, 1024) 1/5 QPSK 19.2
(512, 8, 512) 1/5 QPSK 38.4
(512, 4, 1024) 1/5 QPSK 76.8
(512, 4, 256) 1/5 QPSK 76.8
(512, 4, 128) 1/5 QPSK 76.8
(512, 2, 128) 1/5 QPSK 153.6
Transmission
Format
Code
Rate
Modulation
Type
Nominal Data
Rate (Kbps)
Modulation Parameters (Subtype 2)
(512, 2, 64) 1/5 QPSK 153.6
(512, 1, 64) 1/5 QPSK 307.2
(1024, 16, 1024) 1/5 QPSK 38.4
(1024, 8, 512) 1/5 QPSK 76.8
(1024, 4, 256) 1/5 QPSK 153.6
(1024, 4, 128) 1/5 QPSK 153.6
(1024, 2, 128) 1/5 QPSK 307.2
(1024, 2, 64) 1/5 QPSK 307.2
(1024, 1, 64) 1/3 QPSK 614.4
(2048, 4, 128) 1/3 QPSK 307.2
(2048, 2, 64) 1/3 QPSK 614.4
(2048, 1, 64) 1/3 QPSK 1,228.8
(3072, 2, 64) 1/3 8-PSK 921.6
(3072, 1, 64) 1/3 8-PSK 1,843.2
(4096, 2, 64) 1/3 16-QAM 1,228.8
(4096, 1, 64) 1/3 16-QAM 2,457.6
(5120, 2, 64) 1/3 16-QAM 1,536.0
(5120, 1, 64) 1/3 16-QAM 3,072.0
Transmission
Format
Code
Rate
Modulation
Type
Nominal Data
Rate (Kbps)
Modulation Parameters (Subtype 0/1)
Data rate
(kbps)
Slots per
Packet
Packet Size
(bits)
Code
RateModulation
Number of
Modulation
Symbols
Provided
Repetition
Number of
Modulation
Symbols
Provided
Preamble
(chips)
The
transmitted
packet
38.4 16 1024 1/5 QPSK 2560 9.6 24576 1024 25600
76.8 1024 1/5 QPSK 4.8 512
153.6 4 1024 1/5 QPSK 2560 2.4 6144 256 6400
307.2 2 1024 1/5 QPSK 2560 1.2 3072 128 3200
307.2 4 2048 1/3 QPSK 3072 49/48 6272 128 6400
614.4 1 1024 1/3 QPSK 1536 1 1536 64 1600
614.4 2 2048 1/3 QPSK 3072 49/48 3136 64 3200
921.6 2 3072 1/3 8PSK 3072 49/48 3136 64 3200
1228.8 1 2048 1/3 QPSK 3072 0.5 1536 64 1600
1228.8 2 4096 1/3 16QAM 3072 49/48 3136 64 3200
1843.2 1 3072 1/3 8PSK 3072 0.5 1536 64 1600
2457.6 4096 1/3 16QAM 0.5 64
Preamble
� Assists the AT with synchronization of variable rate
transmissions on the Forward Traffic Channel and Control
Channel
� Contains all ‘0’ and covered by 64-chip (32-chip for
subtype 0 and subtype 1) sequence then repeated several
times according to the transmit mode
Forward Traffic / Control / Preamble
Seq. Repx 2
Coding – Scrambling– Interleaving
Forward Traffic of Control Channel
Physical Layer Packets
TDM
PreambleAll 0’s
Walsh Cover – Gain– Summer
Modulation (QPSK, 8PSK, 16QAM)
Repetition - Puncturing
64 to 1024 chips
Wi 64
QI
QI
QI
QI
I
Coding (1/5) 5120
coding symbol
Forward Traffic Modulation Example
Example for (1024,16,1024) ���� 38.4 kbps
Packet size = 1024
Modulation(QPSK)5120
1 modulation symbol
2560Repetition /Puncturing
(x 9.6)24,576
Preamble(1024 chips) 1024 2457624,576
symbols
25,600 chips
Time-Division Multiplexing
1024 24576
400 64 96 64 400 224 176 64 96 64 400
EVDO uses 4-slot interlace time division multiplexing of users
PilotMAC
1st slot nth slot 2nd slotnth slot nth slot 16th slot
Scheduling Algorithm
� Round Robin (RR) lets every active data flow (that has data packets
in queue) to take turns in transferring packets on a shared channel in a
periodically repeated order
� Maximizing Throughput selects the users which have excellent
channels to get as much data as possible through the system.
� Proportional Fair (PF) takes into account latency while selecting the
user with the largest instantaneous data rate relative to its average
throughput. However, consistently underserved users receive
scheduling priority to promote fairness. Most common scheduling
algorithm used in EVDO.
EVDO Principles
Forward Channel Structure
Reverse Channel Structure
Key Techniques
Reverse Channel Structure
New to Rev A
Reverse Access Channel
� The Access Channel is used by the AT to initiate
communication with the access network or to respond to an
access terminal directed message.
� The Access Channel consists of a Pilot Channel and a
Data Channel.
� The AT shall transmit on the Access Channel at a data
rate of 9.6 kbps (packet size 256) for Subtype 0, data rates
of 9.6,19.2, or 38.4 kbps (packet sizes 256, 512,1024) for
Subtype 1 and Subtype 2.
Access Channel Probe
� Probe � Preamble (Pilot) + Capsule Frames (Pilot + Data)
� The output power of the preamble is independent of the data rate and
is set equal to that of the data portion transmitted at 9.6 kbps.
Pilot channel(I Phase)
Pilot channel(I Phase)
Data channel(Q Phase)
Preamble slots
CapsuleFrames
Pilot channel(I Phase)
Pilot channel(I Phase)
Data channel(Q Phase)
Preamble Frames Capsule Frames
(Access channel physical layer
packets)
Subtype 0Subtype 0
Subtype 1 or 2Subtype 1 or 2
Reverse Traffic Channel
� The Reverse Traffic Channel is used by the AT to
transmit user-specific traffic or signaling information to AN.
� The Reverse Traffic Data Channel is transmitted in
frames = 26.67ms
PILOT RRI
ACK
DRC
Data
Subtype 0 and Subtype 1
PILOT
Aux PILOT
DSCACK
DRC
Data
Subtype 2
RRI
Subframe (4 slots ) is the minimum transmission of the Data channel for Subtype 2
Pilot /Auxiliary Pilot Subchannel
� The Pilot Channel enables coherent demodulation at the
AN.
� In the case of Subtype 0/1 , the pilot is time-division
multiplexed with RRI --- the pilot channel occupies the last
7/8 of one slot.
� The Auxiliary Pilot Channel is used by the AT to aid
reverse link channel estimation by the AN. (Subtype 2 only)
Reverse Rate Indicator Subchannel
� The RRI Channel is used to indicate the payload size and the sub-packet identifier of the physical layer packet transmitted on the Reverse Traffic Channel.
� Subtype 0/1� 3-bit symbol identify corresponding reverse data rate.
� Subtype 2� A 6-Bit RRI symbol used to indicate the data payload size (4-bits) and to provide the sub-packet identifier (2-bits). � The sub-packet identifier of the current transmission facilitates reverse link H-ARQ.� The payload size identification assists in avoiding blind rate detection at the AN.
Data Rate Control Subchannel
� The DRC Channel is used by the AT to indicate to the AN
the requested Forward Traffic Channel data rate and the
selected serving sector on the Forward Channel.
� DRCValue (4-bit) : specifies the requested Forward Traffic Channel data rate� DRCCover (8-ary Walsh cover) : indicates the selected serving sector� DRCLength : number of consecutive slots the DRC is repeated
Serving sector is the sector the AT selects for receiving the Forward Traffic channel
Data Source Control Subchannel
� The DSC Channel is used by the AT to indicate to the AN
the selected serving cell on the Forward Channel.
(Subtype 2 only)
� It provides advance notice of the AT’s intent to switch cell
to reduce inter-cell handoff latency.� DSCValue (3-bit) – indicates the selected serving cell� DSCLength – number of slots the DSCValue stays in effect.
� Time division multiplexed with ACK subchannel and
transmitted on the 2nd half slot.
Serving cell is the cell that contains the serving sector
ACKnowledgement Subchannel
� The ACK Channel is used by the AT to inform the AN whether or not the physical layer packet transmitted on the Forward Traffic Channel has been received successfully.
� Using ACK allow AN to early-terminate multi-slot packet transmission and increase the actual throughput.
� Time division multiplexed with DSC and transmitted on the 1st half slot for Subtype 2.
TypePositive
Acknowledgement
Negative
AcknowledgementUse
Binary Keying 1 -1 Single User Packet
On-Off Keying (OOK) 1 0 Multi User Packet
Reverse Traffic ACK Channel
Reverse Traffic Data Channel
� Supported data rates� 9.6 to 153.6 Kbps (Subtype 0 and Subtype 1)� 4.8 to 1228.8 or optional 1843.2 Kbps (Subtype 2)
� Modulation � BPSK, QPSK or 8-PSK
� Channel coding rate � 1/3 or 1/5
� Subtype 2 introduces Traffic channel to Pilot channel
transmit power ratio (T2P) for reliable estimation of the RL
and quick adjustment of Reverse Traffic Channel data
rates.
QPSK or 8-PSK modulation is used only by Subtype 2
Modulation Parameters (Subtype 2)
Payload Size (bits)
ModulationEffective Data Rate (kbps) Effective Code Rate and Repetition
4 slots 8 slots 12 slots 16 slots 4 slots 8 slots 12 slots 16 slots
128 B4 19.2 9.6 6.4 4.8 1/5 [3.2] 1/5 [6.4] 1/5 [9.6] 1/5 [12.8]
256 B4 38.4 19.2 12.8 9.6 1/5 [1.6] 1/5 [3.2] 1/5 [4.8] 1/5 [6.4]
512 B4 76.8 38.4 25.6 19.2 1/4 [1] 1/5 [1.6] 1/5 [2.4] 1/5 [3.2]
768 B4 115.2 57.6 38.4 28.8 3/8 [1] 1/5 [1.07] 1/5 [1.6] 1/5 [2.13]
1024 B4 153.6 76.8 51.2 38.4 1/2 [1] 1/4 [1] 1/5 [1.2] 1/5 [1.6]
1536 Q4 230.4 115.2 76.8 57.6 3/8 [1] 1/5 [1.07] 1/5 [1.6] 1/5 [2.13]
2048 Q4 307.2 153.6 102.4 76.8 1/2 [1] 1/4 [1] 1/5 [1.2] 1/5 [1.6]
3072 Q2 460.8 230.4 153.6 115.2 3/8 [1] 1/5 [1.07] 1/5 [1.6] 1/5 [2.13]
4096 Q2 614.4 307.2 204.8 153.6 1/2 [1] 1/4 [1] 1/5 [1.2] 1/5 [1.6]
6144 Q4Q2 921.6 460.8 307.2 230.4 1/2 [1] 1/4 [1] 1/5 [1.2] 1/5 [1.6]
8192 Q4Q2 1228.8 614.4 409.6 307.2 2/3 [1] 1/3 [1] 2/9 [1] 1/5 [1.2]
12288 E4E2 1843.2 921.6 614.4 460.8 2/3 [1] 1/3 [1] 1/3 [1.5] 1/3 [2]
E4E2 is 8-PSK/4-ary Walsh cover plus 8-PSK/Binary Walsh cover
Modulation Parameters (Subtype 0/1)
EVDO Principles
Forward Channel Structure
Reverse Channel Structure
Key Techniques
Adaptive Modulation and Coding (AMC)
� The modulation and coding
is dynamically adjusted
according to the condition of
the radio link.
� In the forward link, the C/I is
measured by the AT then
request corresponding data
rate thru the DRC.
� In the reverse link, the
payload size, modulation, and
coding is varied according to
T2P and RAB
0 1000 2000 3000 4000 5000 6000 7000 8000−5
0
5
10
15
slot index
FL
C/I(
dB)
0 1000 2000 3000 4000 5000 6000 7000 80000
500
1000
1500
2000
2500
slot index
Req
uest
ed R
ate(
kbps
)
Reverse Rate Selection (Rel 0)
� The AP determines the condition of the reverse link and sends RAB to the AT
� The AT calculates the probability that it will increase (RAB=not busy) or decrease (RAB=busy) data rate according to the probability vector, P and q.
� The AT compares the result with the Reverse Rate Limit to check whether the threshold is reached.
NotBusy
9.6kbps
19.2kbps
153.6kbps
P1
38.4kbps
76.8kbps
P2 P3 P4
Busy9.6
kbps19.2kbps
153.6kbps
q1
38.4kbps
76.8kbps
q2 q3 q4
Reverse Rate Limit Message is sent by AP to limit the reverse data rate according to the number of active users
Reverse Rate Selection (Rev A)
� The AT adjust the pilot channel power according to the power control
commands received from the AN.
� The AT determines the data channel power which is a relative power
offset to the level of the pilot channel.
� AT calculates T2P for the next transmission according to multiple
inputs, including current T2P and RAB of current active set sectors.
� Based on the T2P, the payload size is identified and so is the reverse
data rate.
� Reverse data rates can vary very quickly and in larger steps
compared to Rel 0 (one step rate change).
Handoff
� FBSS (Fast Base Station
Switching) – the AT keeps
several AP in its active set but
only one AP is serving at any
instance. This is sometimes
referred to as Virtual Soft
Handoff.
AP1AP1
AP4AP4
AP2AP2
AP3AP3
AP1AP1 AP2AP2
TimeTime
Serving APServing AP
t1t1
Serving AP changeServing AP change
Server before t1
Server before t1
Server after t1
Server after t1
current sector forward data rate
Pilot/MAC on FWD linkPilot/DRC/ACK/Traffic on REV Link
(AP’s in AT’s active set)
After handoff AP2 forward data rate
Serving Sector Selection
Serving Sector Selection
-15
-14-13-12-11
-10
-9-8
-7
-6-5
-4-3
-2
-1
012
3
0 2 4 6 8 10 12 14
time, sec
SIN
R, d
B
Sector 0
Sector 1
Serving Sector Index
AT decides the serving sector based on the pilot signal SINR of AP
DSC Operation
� AP scans and measures pilot signal strength of all available sectors to determine if a handoff is necessary.
� As AP moves within the sectors of the same cell, the DSC is maintained while DRCCover may change.
� As AP moves to the coverage of another cell, DSC is sent to relay the intention for handoff to another cell.
� During the transition period, the AP still transmits on the current active cell. This reduces the interruption time due to handoff (typically less than 20ms)
Cell AData Source
Cell BData Source
A1
A2
A3
B2
B3
B1
DRC
DSC A B
A2 A2 A3 A3 B1 B1N N N N
Time
Pilot Strength
N: Null DRCCover
Power Control
� No power control on the forward link.
� Reverse link employ closed-loop and open-loop power
control� In Open-loop power control, the AT will use an algorithm to estimate the minimum necessary transmit power to communicate with the AP.� Closed-loop correction (with respect to the Open-loop estimate) is provided by the AP by sending Power Control Bit (PCB) thru the RPC subchannel. Bit “0” tells the AT to increase power, bit “1” tells the AT to decrease power. Each PCB is either a 1 dB or 0.5 dB step size.