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Enhanced High-Speed Packet Access HSPA+
Background: HSPA Evolution
Higher Data Rates
Signaling Improvements
Architecture Evolution/ Home NodeB
Cellular Communication Systems 2 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
HSPA+
The evolution of UMTS HSPA
Corresponding to UMTS Release 7 and beyond
Motivation of HSPA+
3GPP Long Term Evolution (LTE) being rolled-out, but not backwards compatible with HSPA
556 HSPA networks in service in 203 countries (Oct. 14)**
Investment protection needed for current HSPA deployments
Main goals
Performance and flexibility comparable to LTE in 5 MHz
Optimized packet-only mode for voice and data
Backward compatible with Release 99 through Release 6
Smooth migration path to LTE through commonality and facilitate joint technology operation
Requiring simple infrastructure upgrade from HSPA to HSPA+
HSPA+ defines a broad framework and set of requirements
Improvement of the radio interface
Architecture evolution
**[source: 4GAmericas]
Cellular Communication Systems 3 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
Higher Order Modulations (HOMs)
BPSK
1 bit/symbol
16QAM
4 bits/symbol
64QAM
6 bits/symbol
Uplink Downlink
Increases the peak data rate in a high SNR environment Very effective for micro cell and indoor deployments
Cellular Communication Systems 4 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
Peak Rate Performance Benefits of HSPA+
0
5
10
15
20
25
30
35
40
45
50
Pe
ak
Th
rou
gh
pu
t in
Mb
ps
14
21
28
42
5.7
11.5
HSDPA
HSPA+ 64QAM
HSPA+ 16QAM
2x2 MIMO
HSPA+ 64QAM*
2x2 MIMO
HSUPA
HSPA+ 16QAM
Downlink
Uplink
*Release 8
Uplink and Downlink peak rates similar to LTE peak rates in 5 MHz
Major increase HSPA peak
rates by Higher Order Modulations
Data rate benefits for users in ideal channel conditions (e.g. static users, fixed users close to the cell center, lightly loaded conditions)
Cellular Communication Systems 5 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
HSDPA Performance with 64QAM
Without 64QAM With 64QAM Gain
Cell Throughput 6.9 Mbit/s 7.65 Mbit/s 10.7%
95%-tile User Throughput 7.1 Mbit/s 8.7 Mbit/s 22.5%
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Cat 10/ 15 users Cat 14/ 15 users
thro
ug
hp
ut/
kb
ps
average user throughput 95% user throughput ave. cell throughput
Single micro-cell scenario, advanced receivers required
Cellular Communication Systems 6 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
16QAM for E-DCH
16QAM specified in the uplink for HSPA Evolution, for use with the 2 ms TTI and with 4 multicodes (2xSF2 + 2xSF4)
Increases peak rate from 5.76 Mbps to 11.52 Mbps
Performance results showed:
16QAM requires very good radio conditions
Enhancement of the radio architecture needed (transmitter, receiver)
BPSK
BPSK
BPSK
BPSK
SF2
SF2
SF4
SF4
I
Q
I
Q
SF2
SF4
16 QAM
I
Q
16 QAM
I
Q
Cellular Communication Systems 7 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
16QAM EDCH Performance
Isolated radio cell with good radio conditions (AWGN) and HARQ retransm. rate of 1%
Results show performance for 16QAM above 11 Mbps
Ideal channel conditions
Single user active
Advanced receiver
RLC settings need to be adapted
Larger PDU size
Improved L2 provides some further gain
Cellular Communication Systems 8 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
Coding/Modulation/
Weighting/Mapping
Basic MIMO Channel
The HSDPA MIMO channel consists of 2 Tx and 2 Rx antennas
Each Tx antenna transmits a different signal
The signal from Tx antenna j is received at all Rx antennas i
Channel capacity can be increased by up to a factor of two
Weighting/Demapping
Demodulation/Decoding
Tx Rx
H
HVUH
Cellular Communication Systems 9 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
MIMO in HSPA+
Release 7 MIMO for HSDPA (D-TxAA) 2 x 2 MIMO scheme 4 rank-1 precoding vectors and 4 rank-2 precoding matrices are defined
The rank-2 matrices are unitary (the columns are orthogonal)
The mobile reports the rank of the channel and the preferred precoding weights periodically (PCI)
Dynamic switching between single stream and dual stream transmission is supported by the NodeB scheduler
DOCUMENTTYPE 1 (1)
TypeUnitOrDepartmentHere TypeYourNameHere TypeDateHere
Weight Generation
w 1 w 4
Determine weight info message from the uplink
w 2 w 3
TrCH processing
HS-DSCH TrCH processing
HS-DSCH
Spread/scramble
Primary transport block
Primary: Always present for scheduled UE
Secondary: Optionally present for scheduled UE
Secondary transport block
Ant 1
Ant 2
CPICH 1
CPICH 2
w 1
w 2
w 3
w 4
Cellular Communication Systems 10 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
MIMO Performance Benefits
2x2 D-TxAA MIMO scheme doubles peak rate from 14.4 Mbps to 28.8 Mbps
2x2 D-TxAA MIMO provides significant experienced peak, mean & cell edge user data rate benefits for isolated cells or noise/coverage limited cells
2x2 D-TxAA MIMO provides 20% – 60% larger spectral efficiency than 1x2
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
Near Cell Center Average Cell
Location
Cell Edge
Data
Rate
Gain
of
MIM
O v
s.
SIS
O f
ora
n I
so
late
d C
ell SISO (1x1)
MIMO (2x2)Note: All gains
normalized to
Near Cell Center
SISO Data Rate
0
20
40
60
80
100
Interference Limted
System
Isolated Cell
Sp
ec
tra
l E
ffic
ien
cy
Ga
in (
%)
of
2x
2
MIM
O o
ve
r 1
x2
LM
MS
E
Cellular Communication Systems 11 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
Overview of Dual Cell Operation
3GPP Rel.8 scope:
The dual cell operation only applies to downlink HS-DSCH
Uplink traffic is carried on one frequency
The two cells belong to the same Node-B and are on adjacent carriers
The two cells operate with a single TX antenna
Max two streams per user
Improvements in Rel.9
Dual-Band HSDPA
MIMO in dual cell operation
Dual Cell uplink
Multi-carrier HSDPA
Node-B
F1
UE F2
DL DL
5 MHz 5 MHz
UL
5 MHz
2.1 GHz UL
UTRAN configures one of the cell as the serving cell for the uplink
Cellular Communication Systems 12 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
Dual Cell HSDPA Operation for Load Balancing
Dual Cell HSDPA can optimally balance the load on two HSDPA carriers by scheduling active users simultaneously or on least loaded carrier at given TTI
Simple traffic and capacity model
Avg. Transfer size : 1000 kbyte
Avg. Time between transfers : 60 sec
No gain at very high load
Dual Cell HSDPA operation versus Two legacy HSDPA carriers
0
1000
2000
3000
4000
5000
6000
7000
8000
0 10 20 30 40 50 60
Nb of users in sector footprint
Th
rou
gh
pu
t in
kb
ps
Avg user throughput (2 HSDPA carriers)
Avg Sector throughput (2 HSDPA carriers)
Avg user throughput (Dual Cell HSDPA operation)
Avg Sector throughput (Dual Cell HSDPA operation)
Cellular Communication Systems 13 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
Enhanced Layer-2 Support for High Data Rates
Release 6 RLC layer cannot support new peak rates offered by HSPA+ features such as MIMO & 64QAM
RLC-AM peak rate limited to ~13 Mbps, even with aggressive settings for the RLC PDU size and RLC-AM window size
Release 7 introduces new Layer-2 features to improve HSDPA
Flexible RLC PDU size
MAC-ehs layer segmentation/ reassembly (based on radio conditions)
MAC-ehs layer flow multiplexing
Release 8 improves E-DCH
MAC-i/ MAC-is
Rel.7
2
1500 byte IP packet
RLC-AM
MAC-ehs
RLC-AM PDU
1500
1502 3
MAC-ehs PDU
Traffic flow i for user k
2
1500 byte IP packet
RLC-AM
RLC-AM PDU
1500
1502
Traffic flow j for user k
3
22 bits
80 2 80 2
1500 byte IP packet
RLC-AM
80 2
MAC-hs
80 2 80 2 80 2
RLC-AM PDU
MAC-hs PDU
x19
..
.. Rel.6
Traffic flow i for user k
Cellular Communication Systems 14 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
MAC-ehs in NodeB
MAC-ehs Functions
Flow Control
Scheduling/ Priority handling
HARQ handling
TFRC Selection
Priority Queue Mux
Segmentation
MAC-ehs
MAC – Control
HS-DSCH
TFRC selection
Priority Queue distribution
Associated Downlink Signalling
Associated Uplink
Signalling
MAC-d flows
Priority Queue
Scheduling/Priority handling
Priority Queue
Priority Queue
Segmentation
Segmentation
Segmentation
Priority Queue MUX
HARQ entity
Cf. 25.321
Cellular Communication Systems 15 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
HSDPA – UE Physical Layer Capabilities
HS-DSCH
Category
Maximum
number of
HS-DSCH
multi-codes
Supported Modulation
Formats
Minimum
inter-TTI
interval
Maximum
MAC-hs
TB size
Total number
of soft channel
bits
Theoretical
maximum
data rate
(Mbit/s)
Category 6 5 QPSK, 16QAM 1 7298 67200 3.6
Category 8 10 QPSK, 16QAM 1 14411 134400 7.2
Category 9 15 QPSK, 16QAM 1 20251 172800 10.1
Category 10 15 QPSK, 16QAM 1 27952 172800 14.0
Category 13 15 QPSK, 16QAM, 64QAM 1 35280 259200 17.6
Category 14 15 QPSK, 16QAM, 64QAM 1 42192 259200 21.1
Category 15 15 QPSK, 16QAM 1 23370 345600 23.3
Category 16 15 QPSK, 16QAM 1 27952 345600 28.0
Category 17 15 QPSK, 16QAM, 64QAM/
MIMO: QPSK, 16QAM
1 35280/
23370
259200/
345600
17.6/
23.3
Category 18 15 QPSK, 16QAM, 64QAM/
MIMO: QPSK, 16QAM
1 42192/
27952
259200/
345600
21.1/
28.0
Category 19 15 QPSK, 16QAM, 64QAM 1 35280 518400 35.2
Category 20 15 QPSK, 16QAM, 64QAM 1 42192 518400 42.2
Note: UEs of Categories 15 – 20 support MIMO cf. TS 25.306
Cellular Communication Systems 16 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
E-DCH – UE Physical Layer Capabilities
E-DCH Category
Max. num. Codes
Min SF EDCH TTI Maximum MAC-e TB size
Theoretical maximum PHY data rate (Mbit/s)
Category 1 1 SF4 10 msec 7110 0.71
Category 2 2 SF4 10 msec/ 2 msec
14484/ 2798
1.45/ 1.4
Category 3 2 SF4 10 msec 14484 1.45
Category 4 2 SF2 10 msec/ 2 msec
20000/ 5772
2.0/ 2.89
Category 5 2 SF2 10 msec 20000 2.0
Category 6 4 SF2 10 msec/ 2 msec
20000/ 11484
2.0/ 5.74
Category 7 (Rel.7)
4 SF2 10 msec/ 2 msec
20000/ 22996
2.0/ 11.5
NOTE 1: When 4 codes are transmitted in parallel, two codes shall be
transmitted with SF2 and two codes with SF4
NOTE 2: UE Category 7 supports 16QAM
cf. TS 25.306
Cellular Communication Systems 17 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
Continuous Packet Connectivity (CPC)
Uplink DPCCH gating during inactivity significant reduction
in UL interference
F-DPCH gating during inactivity
UE listens on HS-SCCH only when active
DPDCH
DPCCH
HS-SCCH-less transmission introduced to reduce signaling bottleneck for real-time-services on HSDPA
Prior to Rel.7
Rel.7 using CPC
DPDCH
DPCCH
Cellular Communication Systems 18 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
CPC Performance Benefits
CPC provides up to a factor of two VoIP on HSPA capacity benefit compared to R.99 AMR12.2 circuit voice and 35 – 40% benefit compared to Rel.6 VoIP on HSPA
0
0.5
1
1.5
2
2.5
3
AMR12.2 AMR7.95 AMR5.9Vo
IP C
ap
acit
y G
ain
of
CP
C
R'99 Circuit Voice
VoIP on HSPA (Rel'6)*
VoIP on HSPA (CPC)*
Note: All
capacity gains
normalized to
AMR12.2
Circuit Voice
Capacity
* All VoIP on HSPA capacities assume two receive antennas in the terminal
Cellular Communication Systems 19 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
“Always On” Enhancement of CPC
CPC allows UEs in CELL_DCH to “sleep” during periods of inactivity
Reduces signaling load and battery consumption (in combination with DRX)
Allows users to be kept in CELL_DCH with HSPA bearers configured
Need to page and re-establish bearers leads to call set up delay
Incoming
request Page UE
Paging
Response
Re-establish
bearers
Send data
Without CPC, users
typically kept in
URA_PCH or CELL_PCH
state to save radio
resources and battery
UE in
URA_PCH
CPC allows users to
kept in CELL_DCH
Send data almost
Immediately
(<50ms reactivation)
Incoming
request
UE in
CELL_DCH
Avoids several hundred
ms of call setup delay
CELL_FACH
CELL_DCH
Cellular Communication Systems 20 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
Enhanced CELL_FACH & Enhanced Paging Procedure
UEs are not always kept in CELL_DCH state, eventually fall back to CELL_PCH/URA_PCH
HSPA+ introduces enhancements to reduce the delay in signaling the transition to CELL_DCH use of
HSDPA in CELL_FACH and URA/CELL_PCH states instead of S-CCPCH
Enhanced CELL_FACH
Enhanced Paging procedure
In Rel.8 improved RACH procedure
Direct use of HSUPA in CELL_FACH
Incoming
request Page UE
Paging
Response
Re-establish
bearers
Send data
UE in
URA_PCH
CELL_FACH
CELL_DCH
Use HSDPA for faster
transmission of signaling messages
2ms frame length with up to 4 retransmissions
Cellular Communication Systems 21 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
E-RACH – High level description
RACH preamble ramping as in R.99 with AICH/E-AICH acknowledgement
Transition to E-DCH transmission in CELL_FACH
Possibility to seamlessly transfer to Cell_DCH
NodeB can control common E-DCH resource in CELL_FACH
Resource assignment indicated from NodeB to UE
10 ms
#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4
p
-
a
#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4PRACH
access
slots
10 ms
Access slot set 1 Access slot set 2
#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4
Transmission starts
with power ramping
on preamble
reserved for E-DCH
access
NodeB responds by
allocating common E-DCH
resources
UE starts common E-DCH
transmission.
F-DPCH for power control, E-AGCH
for rate control, E-HICH for HARQ
Cellular Communication Systems 22 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
HSPA+ Architecture Evolution
Integration of some or all RNC functions into the NodeB provides benefits in terms of:
Network simplicity (fewer network elements)
Latency (fewer handshakes, particularly in combination with One-Tunnel)
Synergy with LTE (serving GW, MME, eNB)
Backwards compatible with legacy terminals
Central management of common resources
NodeB
RNC
SGSN
GGSN
Traditional HSPA
Architecture
User Plane
Control Plane
NodeB
RNC
SGSN
GGSN
HSPA with One-Tunnel
Architecture
NodeB+
SGSN
GGSN
HSPA+ with One-Tunnel
Architecture for PS services
Cellular Communication Systems 23 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
Evolved HSPA Architecture – Full RNC/NodeB collapse
2 deployment scenarios: standalone UTRAN or carrier sharing with “legacy” UTRAN
Evolved HSPA
NodeB
SGSN
GGSN
User plane : Iu / Gn
( ” one tunnel ” ) Control
plane : Iu
Iur
Evolved HSPA
NodeB
SGSN
GGSN
User plane : Iu / Gn
( ” one tunnel ” ) Control
plane : Iu
Iur
RNC
NodeB
NodeB
” Legacy ”
UTRAN
Iu
Evolved HSPA - stand - alone Evolved HSPA - with carrier sharing
NodeB+
User plane : Iu / Gn
( ” one tunnel ” ) Control
plane : Iu
Iur
NodeB+
User plane : Iu / Gn
( ” one tunnel ” ) Control
plane : Iu
RNC
NodeB
NodeB
” Legacy ”
UTRAN
Iu
Evolved HSPA - stand - alone Evolved HSPA - with carrier sharing
Cellular Communication Systems 24 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
Home NodeB – Background
Home NodeB (aka Femtocell) located at the customers premise
Connected via customers fixed line (e.g. DSL)
Small power (~100 mW) to only provide coverage inside/ close to the building
Advantages
Improved coverage esp. indoor
Single device for home/ on the move
Special billing plans (e.g. home zone)
Challenges
Interference
Security
Costs
IP Network
UE
Gateway
Operator
CN
Cellular Communication Systems 25 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
CN Interface
Iuh
Iu-CS/PS
Home NodeB architecture principles based on extending Iu interface down to HNB (new Iuh interface)
Approach
Leverage Standard CN Interfaces (Iu-CS/PS)
Minimise functionality within Gateway
Move RNC Radio Control Functions to Home NodeB and extend Iu NAS & RAN control layers over IP network
Features
Security architecture
Plug-and-Play approach
Femto local control protocol
CS User Plane protocol
PS User Plane protocol
HMS interface
RNC HNB-GW
NodeB HNB
RAN Gateway Approach with new “Iuh” Interface
Mobile CS/PS Core
Cellular Communication Systems 26 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
HSPA+ Status & Outlook
The HSPA+ enhancements provide an interim solution for ongoing UMTS network deployment
Investment protection for the existing HSPA operators
Fill the gap before deployment of LTE
Provide alternatives to LTE in some selected areas
Currently, 365 HSPA+ networks are in service in 157 countries (Oct. 2014)**
Almost using 64QAM (often also with DC)
Only a few ones with MIMO
3GPP is working on further HSPA enhancements
Release 10: 4-carrier HSDPA
Release 11: 8-carrier HSDPA, 4x4 HSDPA MIMO, HSDPA multipoint transmission, UL MIMO + 64QAM
Release 12: enhancements on HSDPA signaling, EDCH improvements
**[source: 4GAmericas]
Cellular Communication Systems 27 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
HSPA+ References
Papers:
H. Holma et al: “HSPA Evolution,” Chapter 15 in Holma/ Toskala: “WCDMA for UMTS,” Wiley 2010
R. Soni et al: “Intelligent Antenna Solutions for UMTS: Algorithms and Simulation Results,” Communications Magazine, October 2004, pp. 28–39
4G Americas: “The Evolution of HSPA,” White Paper, October 2011
H. Holma. A. Toskala, P. Tapia (Ed.): “HSPA+ Evolution to Release 12: Performance and Optimization,” Wiley 2014
Standards
TS 25.xxx series: RAN Aspects
TR 25.903 “Continuous Connectivity for Packet Data Users”
TR 25.876 “Multiple-Input Multiple Output Antenna Processing for HSDPA”
TR 25.999 “HSPA Evolution beyond Release 7 (FDD)”
TR 25.820 (Rel.8) “3G Home NodeB Study Item Technical Report”
Cellular Communication Systems 28 Andreas Mitschele-Thiel, Jens Mueckenheim Nov. 2016
Abbreviations
AICH Acquisition Indicator Channel
AMR Adaptive Multi-Rate
BPSK Binary Phase Shift Keying
CLTD Closed Loop Transmit Diversity
CPC Continuous Packet Connectivity
CQI Channel Quality Indicator
DC Dual Channel
DSL Digital Subscriber Line
E-RACH Enhanced Random Access Channel
F-DPCH Fractional Dedicated Physical Control Channel
GW Gateway
HNB Home NodeB
HOM Higher Order Modulation
HSPA High-Speed Packet-Access
IA Intelligent Antenna
LTE Long Term Evolution
MAC-ehs enhanced high-speed Medium Access Control
MAC-i/is improved E-DCH Medium Access Control
MIMO Multiple-Input Multiple-Output
Mux Multiplexing
PARC Per Antenna Rate Control
PCI Precoding Control Information
PDU Protocol Data Unit
Rx Receive
RTT Round Trip Time
SDU Service Data Unit
SAE System Architecture Evolution
S-CPICH Secondary Common Pilot Channel
SDMA Spatial-Division Multiple-Access
SINR Signal-to-Interference plus Noise Ratio
SISO Single-Input Single-Output
SM Spatial Multiplexing
Tx Transmit
VoIP Voice over Internet Protocol
16QAM 16 (state) Quadrature Amplitude Modulation
64QAM 64 (state) Quadrature Amplitude Modulation