ETRI Proposal
Heesoo Lee
heelee@etri.re.kr
Contents
•
•
•
•
Basic aspects
Downlink
Uplink
Salient features
– Multiuser precoding MIMO
– Intercell interference management for downlink
(Virtual MIMO)
– Intercell interference management for uplink
(Whispering resource)
– Macro diversity in multicast/broadcast
Basic Aspects
Basic Aspects
• Duplexing
– FDD
• User Multiplexing/Multiple Access
– Downlink : OFDMA
– Uplink : SC-FDMA
• Modulation
– QPSK, 16QAM, 64QAM (Optional in Uplink)
• Data Channel Coding
– LDPC : Mandatory
– Convolutional turbo code : Optional
– Code rate : 1/4 ~ 4/5
• H-ARQ
– Chase combining and Type-II & Type-III H-ARQ
Basic Aspects
• Multiple antenna transmission
– Medium to high speed users
• STBC
• Spatial multiplexing
– Low speed users
• Multi code words (MCW) transmission
• Multi user precoding MIMO
– S-PUSRC (SIC-based Per User & Stream Rate Control)
• Adaptive transmission
– Frequency domain adaptation : chunk based channel
– Time domain adaptation : short TTI (0.5 ms)
– Space domain adaptation : SDMA (Multi-user
precoding MIMO)
Basic Aspects
• Intercell Interference Management
– Downlink
• Virtual MIMO based on coordinated symbol repetition
– Intercell interference cancellation
– Full frequency reuse
– Cell planning not required
– Uplink
• Inter-cell interference avoidance/concentration with resource
coordination
– Full frequency reuse
– Cell planning required to optimize performance
• Multicast/Broadcast support
– Space-time (or frequency) diversity among cells
– Rotation of STBC (or SFBC) antenna combining
pattern
Downlink
Downlink OFDM Parameters
• Scalable Channel Bandwidth
10 MHz
5 MHz
Transmission BW
Sub-frame duration
0.5 ms
Sub-carrier spacing
15 kHz
15 MHz
20 MHz
Sampling frequency
7.68 MHz
(2  3.84 MHz)
15.36 MHz
(4  3.84 MHz)
23.04 MHz
(6  3.84 MHz)
30.72 MHz
(8  3.84 MHz)
FFT size
512
1024
1536
2048
Number of occupied
sub-carriers
301
601
901
1201
(4.73/109)  2,
(4.77/110)  5
(4.75/146)  5,
(4.79/147) 2
Number of OFDM symbols
per sub frame (DTP)
CP length (μs/samples)
7
(4.69/36)  3,
(4.82/37)  4
(4.75/73)  6,
(4.82/74)  1
Frame Structure
•
•
•
•
Frame duration : 20ms
Subframe (DTP) duration : 0.5ms
Partition of resources : RS0 ~ RS10
RS7~10 are further divided into several resource subspaces
(RSS)
DTP #0
DTP #1
DTP #2
DTP #19
TDTP
Tframe
Downlink
Traffic
Packet
RS0
RS7
RS1
RS8
RS2
RS3
RS4
RS5
RS6
RS9
RS10
Physical Channels
• DPICH
– Downlink pilot channel
• CCFPCH
– Control Channel Format Physical Channel
• CCPCH
– Common Control Physical Channel
• SCPCH
– Shared Control Physical Channel
• DSDPCH
– Downlink Shared Data Physical Channel
DPICH
• Support four transmit antennas
– DPICHi
2
0
2
1
3
1
4
D
D
D
0
2
0
2
1
3
1
3
D
D
D
D
0
2
0
2
1
3
1
3
D
D
D
Frequency
• Pilot symbol modulation
• Joint channel estimation for
multiple cells
0
D
• Channel estimation for antenna i
• Resource space RS0, RS1, RS5, and
RS6, are used for DPICH0,
DPICH1, DPICH2, and DPICH3
respectively.
– Orthogonal sequences among
sectors
– Pseudo Random M-PSK sequences
among cells
Time
Subframe
D
0
2
0
2
1
3
1
3
D
D
D
D
0
0
1
1
D
D
D
D
0
0
1
1
D
D
D
D
0
0
1
1
D
D
D
D
0
0
1
1
Control Physical Channels
• CCFPCH
– SCPCH format information
– RS2 is used.
• CCPCH
– Broadcasting common control information
– RS3 is used.
• SCPCH
– ARQ information, scheduling information for up/down
physical data channels
– RS4 is basically used.
– RS7 is additionally used if necessary.
DSDPCH
• Transmit user data
• A maximum of 40 DSDPCHs in a subframe (DTP) for 10MHz channel
bandwidth
• Modulation
– QPSK, 16QAM, 64QAM
• Channel coding
– LDPC, Convolutional turbo code
– Code rate : ¼ ~ 4/5
• Each DSDPCH consists of a number of DSDSCHs (Downlink Shared
Data Sub-Channels)
• Four types of DSDSCH
–
–
–
–
DS-DSDSCH (Distributed & Spreading type DSDSCH)
DN-DSDSCH (Distributed & Nonspreading type DSDSCH)
LN-DSDSCH (Localized & Nonspreading type DSDSCH)
LS-DSDSCH (Localized & Spreading type DSDSCH)
DS-DSDSCH
• DS-DSDSCH
–
–
–
–
There are 3*DRS7 (Dimension of RS7) DS-DSDSCHs.
Each DS-DSDSCH consists of a RSS of RS7.
Distributed channel structure
Spread each symbol over a DSB (Distributed spreading
block)
– A DSB consists of 3 distributed frequency-time bins.
• Spreading factor is 3.
– Spreading and scrambling sequence
• Orthogonal spreading sequences among sectors
• Pseudo random scrambling sequence among cells
– Apply interference cancellation with Virtual MIMO
– Assigned to high speed users suffering from large
intercell interference
DN-DSDSCH
• DN-DSDSCH
– There are 3*DRS8 (Dimension of RS8) DNDSDSCHs.
– Each DN-DSDSCH consists of a RSS of RS8.
– Distributed channel structure
– Assigned to high speed users relatively free
from intercell interference
LN-DSDSCH
• LN-DSDSCH
– There are 3*DRS9 (Dimension of RS9) LNDSDSCHs.
– Each DS-DSDSCH consists of a RSS of RS9.
• A RSS of RS9 consists of a chunk (15 consecutive
subcarriers)
– Localized channel structure
– Not spread symbols
– Assigned to low speed users relatively free
from intercell interference
LS-DSDSCH
• LS-DSDSCH
– There are 3*DRS10 (Dimension of RS10) LS-DSDSCHs.
– Each LS-DSDSCH consists of a RSS of RS10.
• A RSS of RS10 consists of a chunk (15 consecutive subcarriers)
– Localized channel structure
– Spread each symbol over a LSB (Localized spreading block)
– A LSB consists of 3 consecutive frequency-time bins.
• Spreading factor is 3.
– Spreading and scrambling sequence
• Orthogonal spreading sequences among sectors
• Pseudo random scrambling sequence among cells
– Apply interference cancellation with Virtual MIMO
– Assigned to low speed users suffering from large intercell
interference
Resource Space Partition
0.5ms
• Example : 10MHz
• RS0~RS4
–
OFDM symbol
– Distributed
frequency
1st
• RS5~RS6
–
2nd
OFDM symbol
• RS7~RS10
– Over 2nd ~ 7th OFDM
symbols
– Unit of allocation
• BCS : Bundle of chunk
– Variable size
• Parameters
– DRS7 ~ DRS10
600 x 7 = 4200
600
tone
time
Ts#0
Ts#1~Ts#6
15
tone
RS0=4n+0
RS2=64n+2,3
RS3=8n+2,3 but
exclude RS2
RS1=4n+1
RS4=rest all
RS0
RS1
RS3
RS3
RS0
RS1
RS4
RS4
RS5
RS6
Ts#0
Ts#1
cs0
cs1
cs2
cs3
cs4
cs5
cs6
cs7
cs8
cs9
cs10
cs11
cs12
cs13
cs14
cs15
cs16
cs17
cs18
cs19
cs20
cs21
cs22
cs23
cs24
cs25
cs26
cs27
cs28
cs29
cs30
cs31
cs32
cs33
cs34
cs35
cs36
cs37
cs38
cs39
BCS0
BCS1
BCS2
DRS7
BCS3
BCS4
BCS5
DRS8
BCS6
BCS7
BCS8
BCS9
DRS9
BCS10
BCS11
BCS12
DRS10
BCS13
RS5
RS6
RS5
Time positioin : Ts#1
Frequency position : RS9,RS10
4n+0
RS6
Time position : Ts#1
Frequency position : RS9,RS10
4n+1
DSB1,0
DSB0,0
RSS7,0
RSS7,1
RSS7,2
RSS7,3
RSS7,4
RSS7,5
T s#1
T s#2
T s#4
# of RSS7,n =3u
Ts #3
RSS8,0
RSS8,1
RSS8,2
RSS8,3
RSS8,4
RSS8,5
T s#5
T s#6
# of RSS 8,n =3v
BCS3
BCS2
BCS1
BCS0
RS 8;
DRS8 =2
RS 7;
DRS7 =2
Resource Subspace partition
DSB1,0
0,0
DSB
0,0
DSB
RSS7,0
RSS7,1
RSS7,2
RSS7,3
RSS7,4
RSS7,5
Ts #1
Ts #2
Ts #4
# of RSS7, n =3*DRS7
Ts #3
Ts #5
Ts #6
BCS1
BCS0
DRS7 =2
RS7 ;
Resource Subspace for RS7
Ts #1
Ts #2
Ts #3
Ts #4
RSS8,0
RSS8,1
RSS8,2
RSS8,3
RSS8,4
RSS8,5
Ts #5
Ts #6
# of RSS8, n =3v
BCS3
BCS2
DRS8 =2
RS8 ;
Resource Subspace for RS8
Uplink
Uplink Transmission
• Single carrier FDMA based system
– Orthogonal transmission within cell
• Modulation:
– QPSK, 16QAM
– Optional: 8PSK, 64QAM
• Channel coding
– LDPC and convolutional Turbo code
– Code rate: 4/15~4/5
• MIMO
– Up to 2 transmit antennas
– Up to 4 receive antennas
• Inter-cell interference avoidance/concentration with
resource coordination
SC-FDMA (1)
Input
Bit Stream
s0
s1
Constellation
Mapping
Serial to
Parallel
sM 1
•
•
•
M-point
DFT
Spreading
S0
S1
S M 1
Low PAPR
Cyclic prefix guard interval: enable
cost-effective frequency domain
block processing at receiver side
Two types of SC transmission
– Localized transmission: multi-user
scheduling gain in frequency
domain
– Distributed transmission: robust
transmission for control channels
and high mobility UE
X0
X1
Symbol to
subcarrier
mapping
x0
x1
N-point
IFFT
Parallel
to serial
Add
Cyclic
Prefix
xN 1
X N 1
0
M-point
DFT
Spreading
Symbol to
subcarrier
mapping
0
N-point
IFFT
0
Localized: contiguous subcarriers
0
0
M-point
DFT
Spreading
Symbol to
subcarrier
mapping
0
N-point
IFFT
0
Distributed: evenly spaced subcarriers
SC-FDMA (2)
•
Localized transmission
– Need to feedback channel state information
– Mainly for low-to-medium mobility users
•
Distributed transmission
– Mainly for high mobility users
•
Orthogonal resource subspace division
– Transmission bandwidth is divided into localized band and distributed band
– Each band is further divided into several subbands for inter-cell interference
avoidance/concentration
– A subband out of each band in a cell is operated in whispering mode; UEs using a
channel belonging to the same subband in neighboring cells can be operated in
speaking mode
Localized band
Distributed band
D-subband 2
L-subband 3
L-subband 3
L-subband 3
frequency
* Different colors denote different UEs’ channel
D-subband 1
D-subband 3
SC-FDMA Parameters
Transmission BW
5 MHz
10 MHz
Subframe duration
0.5 ms
Subcarrier spacing
15 kHz
15 MHZ
20 MHz
Sampling frequency
7.68 MHz
15.36 MHz
23.04 MHz
30.72 MHz
FFT size
512
1024
1536
2048
Number of occupied
subcarriers
301
601
901
1201
Number of blocks of
symbols per subframe
CP length (us/samples)
6 Long blocks + 2 Short blocks
(4.04/31)  7,
(5.08/39)  1
(4.1/63)  7,
(4.62/71)  1
(4.12/95)  7,
(4.47/103)  1
(4.13/127)  7,
(4.39/135) 1
Frame Structure
•
•
Frame duration: 10 msec
One frame consists of 20 UTPs (Uplink Traffic Packet, UTP and sub-frame are
the same in this context)
– UTP: 0.5 msec
– UTP: 6 regular symbol blocks + 2 half-length symbol blocks
Tframe=10msec
TUTP=0.5msec
UTP #0
C
P
LB #1
UTP #1
C
P
SB
#1
C
P
LB #2
UTP #2
C
P
LB #3
UTP #19
C
P
LB #4
C
P
LB #5
C
P
SB
#2
C
P
LB #6
Pilot Channel
• Pilot
– For uplink channel quality
measurement (channel
sounding)
– For channel estimation and
coherent detection at receiver
side
N subcarriers for regular blocks (long blocks)
• TDM pilot structure
– Easy to keep low PAPR
characteristic
– Pilot symbols are carried on
two short blocks
– Support both localized and
distributed channels
• Alternating transmission for
fitting into short block structure
N/2 subcarriers: even-numbered pilot subcarriers are
transmitted via SB #1
N/2 subcarriers: odd-numbered pilot subcarriers are
transmitted via SB #2
Physical Channels
• SPDCH (Shared Physical Data Channel): transmit data traffic and
some data-dependent control signals.
• SCPCH (State Control Physical Channel): transmit control signal for
state management of user equipments.
• UACH (Uplink ACK Channel): transmit ACK/NACK information
responding to downlink data channel.
• UFCH (Uplink Feedback Channel): transmit feedback information for
downlink transmission.
• PFCH (Path-loss Feedback Channel): transmit long-term channel
quality of serving and neighboring cells for uplink interference
coordination
• Additional physical channels for link set-up, synchronization, etc.
Channel Multiplexing
•
Multiplexing of Shared Channels:
– TDM pilot structure is used
– Data-independent control channels are multiplexed in frequency domain
– UE data and data-dependent control are multiplexed in time domain
Tframe=10msec
TUTP=0.5msec
UTP #0
UTP #1
UTP #2
UTP #19
frequency
data independent Control
Pilot
Data and
data-dependent Control
Pilot
time
Multiuser Precoding MIMO
S-PUSRC
• Multiuser multistream precoding MIMO
• S-PUSRC
– Transmitter and receiver structure
– Feedback information
– Scheduling rule
• Capacity comparison
Multistream precoding MIMO
• Transmission of multiple parallel streams
– Independent coding for each stream
– Per stream rate control
– Known to achieve open-loop MIMO capacity when
combined with stream-by-stream SIC reception
• Precoding
– Precoding vector for each stream (phase and amplitude
variation across transmit antennas)
– Choice of precoding matrices (or vectors) depending on
cell environment and UE channel
Multiuser MIMO
• Single-user MIMO schemes
–
–
–
–
PARC, S-PARC etc.
All streams to one user
Stream-by-stream SIC
Spatial domain multiuser
diversity is NOT available
User 1
Channel 1
Data 1
Data 2
BS
Channel 2
User 2
Data 3
Channel 3
User 3
Single-user MIMO
• Multi-user MIMO schemes
– PU2RC
– Multistreams to multiple users
– Spatial domain multiuser
diversity
– Larger diversity gain than singleuser MIMO
– Stream-by-stream SIC is NOT
available
User 1
Channel 1
Data 1
Data 2
BS
Channel 2
User 2
Data 3
Channel 3
Multi-user MIMO
User 3
S-PUSRC
• SIC based Per User and Stream Rate Control (S-PUSRC)
– Multiuser precoding MIMO (multiple precoded streams to multiple users)
– Spatial domain multiuser diversity gain
– Ordered stream-by-stream SIC
– Feedback information
• stream order for SIC, SINRs for multiple streams
User 1
Channel 1
Data 1
Data 2
BS
Channel 2
User 2
Data 3
Channel 3
User 3
S-PUSRC
• Transmitter structure
S-PUSRC
• Receiver structure
S-PUSRC
• Feedback information
– SIC order information: the stream with the largest post-detection
SINR is first decoded and cancelled at each step of SIC.
– Post-detection SINRs for each stream under the assumption of perfect
cancellation of the stream with preceding orders
• Multiuser scheduling with the following constraints
– One data stream cannot be allocated to more than one user.
– When n streams are to be allocated to a user, these should be the first n
consecutive streams in the decoding order list of the user.
• Note that the scheduling constraints enable stream-bystream SIC at the receiver
S-PUSRC
• Scheduling example
UE
Decoding order of data streams
UE1
3 1 4 2
UE2
2 3 1 4
UE3
4 2 1 3
– If streams 2 and 3 have been allocated to UE2 and stream 4 to
UE3, the remaining stream 1 cannot be allocated to UE1 or UE3.
– If streams 3 and 1 have been allocated to UE1, streams 2 and 4 can
be allocated to UE2 and UE3, respectively.
Capacity comparison
• Capacity of multi-stream MIMO in multi-user environment
C

1 k  M

log 2 1  SINRk

– PARC: all streams to the UE with the largest capacity
– PU2RC: each stream to the UE with the largest SINR
for the stream
– S-PUSRC: multiuser stream allocation for a maximum
capacity under the scheduling constraints
Capacity comparison
Capacity comparison
• S-PUSRC gives the largest capacity regardless of
the number of users
– Small number of users
• SIC gain, similar to PARC
– Large number of users
• Spatial-domain multiuser diversity gain, similar to
PU2RC
• S-PUSRC achieves both SIC and spatial-domain
multiuser diversity gain.
Intercell interference management
for downlink (Virtual MIMO)
Virtual MIMO
• Downlink inter-cell interference mitigation
–
–
–
–
Coordinated symbol repetition
Transmission and Detection
Resource partitioning and allocation
Simulation results
Coordinated symbol repetition
– Inter-cell interference mitigation based on coordinated
symbol repetition for cell-edge UEs and control
channels
– The resources for symbol repetition of one cell/sector
are set to exactly collide with those of other cell/sectors.
• Identical repetition-resource allocation among
different cell/sectors
S1
R(f1,t1)
R(f1,t1)
R(f2,t2)
R(f2,t2)
BS
BS
UE
S2
Coordinated symbol repetition
• The transmission and reception is equivalent to a
MIMO system (thus, called virtual MIMO)
• Symbol detection using ZF, MMSE, IC etc
Cell-edge UE
f1,
f2
S1
S2
Serving Cell
Interfering Cell
“2 X 2 Virtual MIMO”
Repetition-resource allocation pattern
Repetition factor G
Cluster type
- Localized data subchannels
Comb type
- Control channels
- Distributed data subchannels
Block-random type
Joint detection on repeated symbols
• Received signal
• Repetition factor G
• Number of cell/sectors J (G ≥ J)
R  Hs + n
 R1   h11c11
  
 R2    h21c21
 :   :
  
 RG   hG1cG1
received signals
data symbols from J cell/sectors
h12 c12 ... h1J c1J   s1   n1 
   
h22 c22 ... h2 J c2 J   s2   n2 




 : 
:
.
:
:
   
hG 2 cG 2 ... hGJ cGJ   sJ   nG 
scrambling/orthogonal codes
Joint detection on repeated symbols
• Combining weights
Ŝ = WR
1
MMSE: WMMSE
1
 

= H H 
J  H
SNR 

1
ZF: WZF =  H H  H 

Code sequences for detection performance
improvement
• To enhance symbol detection, double-layered
sequences are multiplied to repetition symbols
• Cell-specific scrambling sequences as signature
randomizers e.g. M-ary random phasors
» Easy cell planning
» Improve diversity among repetition symbols
• Sector-specific orthogonal codes
» Minimize correlation between the desired symbol and
interfering symbols from neighboring sectors within the
same cell.
Resource partitioning and allocation
• Logical resource partitioning
– Two large resource blocks
» Type-A resources for traffic channels
» Type-B resources for control channels
– Type-A resource block
» Subblock A1 for interference-free UEs
» Subblock A2 for interference-susceptible UEs
Resource partitioning and allocation
– Every cell adopts the same resource allocation
scheme.
– The sizes of subblocks A1 and A2 can be
adjusted dynamically by taking into account the
interference-susceptible traffic.
Resource allocation (geographical)
Traffic channels
Control channels
Simulation results
• Simulation parameters
–
–
–
–
–
–
–
–
Number of cells
Modulation
Repetition factor
Scrambling sequence
Channel
Joint symbol detection
Subcarrier allocation
Ideal channel estimation
:3
: QPSK
:4
: Random 8PSK phasors
: Pedestrian A (3 km/h)
: ZF
: Comb type
Simulation results
Ped A, Repetition 4, SIR 0dB
0
10
-1
10
-2
BER
10
-3
10
-4
10
-5
10
-6
10
0
5
10
15
EbNo
20
25
30
Intercell interference management
for uplink (Whispering resource)
Directivity of Interference (UL)
• For a UE in UL, there exists a neighboring BS (or
BSs) suffering from severe interference.
Small Interference
Medium Interference
Big
Interference
Small Interference
Medium Interference
Concentration of Interference (UL)
• By concentrating big interferers, it becomes usual
that big interference doesn’t exist.
Small
Interference
Big
Interference
Medium
Interference
Medium
Interference
Medium
Interference
Special Case
Usual Case
Small
Interference
New ICI Management (UL)
• ICI Management Based on
Avoidance/Concentration of Interference
– Concentrating big interference using directivity of
interference
• Large increase of SIR for most cases
• Serving users only with very good channels in special case
• Predictable ICI with bound: even the denominator of S/I
– Large Increase of SIR for Cell Boundary Users
• Large increase of fairness among users
• Increase even in total system throughput
ICI Management Procedure (UL)
• ICI Vector
– Interference relation between a UE and each neighboring BS
measured by pilot
• Resource Region Allocation by BS Based on ICI Relations
of Each UE
– Orthogonal resources such as frequency and time are divided as
follows:
• Special case: whispering resource region
– Big ICI from adjacent cells
• Usual case: speaking resoure region
– Small ICI from adjacent cells
– Permitted generation of big ICI toward a specific direction (or BS)
• Isolated case possibly by irregular cellular deployment: private
resource region
– Small ICI from adjacent cells
– No generation of big ICI
Geographical Resource Allocation
W2
S1
W7
S1
W3
S2
S3
S7
S1
W1
S6
S1
W6
S4
S5
S1
S1
W5
• W: whispering
• S: speaking
• Simultaneous activation of the same numbers
W4
Distribution of Whispering Resource
• Only One Concurrent Whispering Resource
– 7-cell structure
– The cycle of whispering cells: 7
W
W
W
W
W
W
Assumptions for Simulation
• MS Distribution
– Uniform over cells, random generation
• Traffic Generation
– Always queued
• Channel
– Correlated shadowing without fast fading (no mobility)
• Resource Allocation
– The same amount of resource (or time) allocation for all MS’s
regardless of position or channel
– Proportional fair (PF) scheduling without channel variation 
similar to round robin
Simulation Measure
• SIR Distribution
– No link-level result
• No SIR-capacity-BLER result
– 95% worst SIR (5th percentile) from SIR distribution 
Measure
• Only in UL
C
 log 2 1  SNR   log 2 1  SIR 
• Shannon capacity in AWGN :
W
pdf
95% worst SIR
SIR
SIR Distribution in UL
– Resource region decision threshold
• The smallest path loss value from neighboring BSs
under a fixed UE power
pdf of SIR
-1
cdf of SIR
0
10
10
conventional UL
proposed UL
-2
-1
10
10
Excluding inferior 5%
cdf
pdf
10dB
-3
-2
10
10
-4
10
-20
9dB
Excluding inferior 1%
conventional UL
proposed UL
-3
-10
0
10
20
30
SIR(dB)
40
50
60
70
10
-20
-15
-10
-5
0
5
SIR(dB)
10
15
20
25
30
Capacity Distribution in UL
pdf of C/W
cdf of C/W
0
10
conventional UL
proposed UL
-1
10
-1
10
cdf
pdf
-2
10
-2
10
-3
10
-4
10
conventional UL
proposed UL
-3
-1
10
0
1
10
10
C/W
10
-2
10
-1
10
0
10
C/W
1
10
Reduced Number of Resource Regions
W2
W2
S1
W3
S1
W3
S2
S3
S3
S1
W4
S1
S1
S1
W2
S3
S4
S1
W1
W1
S2
W3
S2
S2
S3
S1
S1
S1
W2
W3
S3
S4
S2
S1
W3
W2
Pattern 3
Pattern 4
S1
W4
• Easier radio frame design
• Less ICI management gain, but more frequency
scheduling gain
Rotation of Resource Regions
frequency
W1
S4
S3
S2
S2
W1
S4
S3
S3
S2
W1
S4
S4
S3
S2
W1
time
• Frequency scheduling gain for delay insensitive
traffic
UE Nonuniformness
• Maintaining the size of each resource region
– Excessive UEs are moved to other regions.
– Moving UEs from a whispering resource region to speaking
resource regions does not affect other UEs.
– Moving UEs from a speaking resource region to other regions will
force them to reduce their transmission power.
• Changing the ratio of resource regions
– Enlarging a whispering resource region does not affect other cells.
– Enlarging a speaking resource region in cell A will force the
corresponding whispering resource region in the neighboring cell
to be enlarged. The disjoint whispering resource region of cell A
has not to be shrunk.
Irregular Multi-Cellular Environments
• The Number of Patterns: 7, 3, 4, etc.
– Adjacent two cells do not hold the same pattern in
common for efficiency.
• When all patterns are consumed in adjacent cells,
– The whispering resource region of the cell can be determined
randomly.
• Pattern Allocation
– Occurrence of pattern allocation/reallocation
• First system deployment
• New insertion of a cell
– Pattern adjustment
• After some period for gathering path loss information between
a UE and its neighboring Node B’s, each Node B determines
which Node B’s are adjacent to it with UEs as mediators.
Sectored Multi-Cells
• Three sectored multi-cells are equivalent to omnicells in neighboring relations.
Macro diversity in
multicast/broadcast
Proposed Macro Tx Diversity Method
• 2 cell group case
– Space frequency block coding
(SFBC) between 2 cell groups
t
X
S0
S1
S0
t
X
S1
S0
f
S1
S0
S1
S0
S1
S0
Cell Planning
X  {..., X (2k ), X (2k  1),...}
X  {...,  X (2k  1)*, X (2k )* ,...}
S1
Proposed Macro Tx Diversity Method(2)
• 3 cell group case
– A coded packet is divided into the
three parts
– Different cell group combinations
for SFBC in each part
x0
x1
x2
X  {x0 , x1 , x 2}
C2
C1
C0
x
x0

0
C1
x1
C0
C2
C1
t
x 2
C2
C1
x1
x2
C1
f
C0
Cell Planning
C0
C2
t
Cell Sites with 2 Tx Antennas
• Conventional method
• Proposed method
Tx#2
Tx#1
Tx#1
X
Tx#2
X
X  {x0 , x1 , x 2}
Tx#1
X
Tx#2
X
Tx#1
X
Tx#2
X
x0
x 0
x1
x1
x 2
x2
Tx#1
Tx#2
Tx#1
Tx#2
x0
x

0
x 0
x0
x1
x1
x1
x1
x2

2
x2
x 2
C1
x
C0
C2
Simulation Parameters
Parameters
Values
Carriers frequency
2 GHz
Bandwidth
5 MHz
Sampling frequency
7.68 MHz
OFDM symbol duration
66.66 us
OFDM guard interval
16.67 us
FFT size
512
# of used subcarriers
300
# of resources / sub-frame
300 subcarriers 6 OFDM symbols
= 1800 resources
# of pilot resources / sub-frame
150 (300 for 2 antennas)
# of data resources / sub-frame
1650 (1500)
Turbo code
(N,K)
QPSK
K=1280, N=3300 (3000)
Code rate = 0.39 (0.43)
Simulation Conditions
• Three cell configuration
Q0
A
Q1
Q2
Q0
A
Q2
B
Q1
C r
C r
B
CG C0
CG C1
CG C2
CG S0
CG S1
(a) 2 Cell Groups
(b) 3 Cell Groups
Cell border performance for single antenna
0
0
10
10
Conv.
2CG
3CG
Conv.
2CG
3CG
-1
-1
10
PER
PER
10
-2
10
-3
-3
10
10
-4
10
-2
10
-4
0
1
2
3
4
5
6
Average Es/No
Ped-A 3km/h
7
8
9
10
10
0
1
2
3
4
5
6
Average Es/No
Veh-A 60km/h
7
8
9
Cell interior performance for single antenna
0
0
10
10
Conv.
2CG
3CG
Conv.
2CG
3CG
-1
10
-1
PER
PER
10
-2
10
-2
10
-3
10
-3
10
0.3
-4
0.4
0.5
0.6
0.7
0.8
0.9
1
10
0.3
0.4
0.5
0.6
0.7
0.8
DISTANCE
DISTANCE
Ped-A 3km/h
Veh-A 60km/h
0.9
1
Cell border performance for two antennas
0
0
10
10
Conv.
3CG
Conv.
3CG
-1
-1
10
PER
PER
10
-2
10
-3
-3
10
10
-4
10
-2
10
-4
0
1
2
3
4
5
Average Es/No
Ped-A 3km/h
6
7
8
10
0
1
2
3
4
5
Average Es/No
Veh-A 60km/h
6
7
8
Cell interior performance for two antennas
0
0
10
10
Conv.
3CG
Conv.
3CG
-1
-1
10
PER
PER
10
-2
10
-3
-3
10
10
-4
10
0.6
-2
10
-4
0.65
0.7
0.75
0.8
0.85
DISTANCE
Ped-A 3km/h
0.9
0.95
1
10
0.6
0.65
0.7
0.75
0.8
0.85
DISTANCE
Veh-A 60km/h
0.9
0.95
1