Distortion Management of Real-time MPEG-4 FGS
Video over Downlink Multicode CDMA Networks
Guan-Ming Su, Zhu Han, Andres Kwasinski, Min Wu, K. J.Ray. Liu, and Nariman Farvardin
Streaming Video
System Description
™Transmitting real-time compressed video over
multicode CDMA network is an emerging service.
™ To provide subscribers with satisfactory received
qualities, we face a critical issues: the system’s
resources are limited.
™ We formulate this system as an optimization problem
to achieve minimal overall distortion received by all
users subject to the available number of codes and
maximal power for transmission. We propose a fast
algorithm to solve this problem.
Proposed Algorithm
B ase
Layer
Mobile Receiver
for User 1
Mobile Receiver
for User N
R e lie v in g P s u m b y
u s in g u p a c o d e
( T a b le I )
Base Station
Transmitter
Channel Coding
Rate Assignment
Variable Rate
Channel Encoder
N
A t the stream ing serve r
Multiple
Codes
Code 1
Channel Coding
Rate Assignment
r1
!C
Psu m
Ë
yes
N
j 1
?
!
c
j
Pm a x
C
no
Code C
O n ly if a ll
a s s ig n m e n ts w o u ld
e xce e d P m ax
A s s ig n n e w c o d e to m in im iz e
d is t o r t io n ( T a b le II )
Feedback Downlink
Channel Information
rN
Multiple
users
Video
Program
User 1
yes
?
D
D
j
m in
j
D one
FGS Encoder
Video
Program
User N
Experimental Results
Problem Formulation
F G S E nh anc em e nt Lay er
C
j
yes
Variable Rate
Channel Encoder
A t th e d ecode r
F G S E nha nc em e nt L ay er
j
no
no
FGS Encoder
c
1
Modulator
Spreader
TC
?
c
1
R e d u c e d is t o r tio n b y
in c r e a s in g p o w e r
(T a b le III)
?
Ë
Power Control
Distortion Management/Resource Allocation Protocol
P o rtio n o f the F G S en hance m e nt
layer tra nsm itted
A t th e e ncode r
j
yes
O u ta g e
j
™ MPEG-4 FGS codec consists of base and FGS layer.
™ FGS coding enables a video sequence to be encoded
once, and transmitted/decoded at different rates
according to the available bandwidth
F G S E nh an cem e nt La yer
no
no
+
Modulator
Spreader
T1
E ncod ed F G S
E nh ancem en t Layer
N
Ë
?
Psu m ! Pm a x
yes
FG S
Layer
Power Control
R 0j - ß
à
T m ax R à
j
to a ll u s e rs
R e lie v in g P s u m b y
u s in g u p a c o d e
( T a b le I )
MPEG-4 FGS Video
Ï
Ðc
Ð
A s s ig n
Wireless
Channel
Psum and Dsum v.s. Number of codes in use
300
1500
™ Point A: base layer of each
user is allocated. System is
power unbalanced, assign
code to reduce power.
™ Point B: System is not
power unbalanced, assign
codes to reduce distortion
™ Point C: All codes are
assigned but Psum < Pmax.
Use remaining power to
reduce distortion.
C
P
I
P
P
P
B ase L aye r
Channel Coding and Power Control
™ The received SINR for assigning code i to user j :
* (W / R ) ½( P G /(G ËH P Œ ))
C
2
i
i
j
j
ki k
k 1, k Ÿi
™ Targeted SINR can be approximated as a function of
channel coding rate Ni 2 AT B .
™ To maintain BER below 10-6 such that the video quality
is controllable through noisy channel, the received
SINR should be no less than the targeted SINR. This
can be achieved using adaptive channel coding and
power control.
™The overall required power can be approximated as
i
C
Psum
Ë
i 1
where Yi
Π2Yi
Gi
C
C
ËË
Π2HkiYiYk
Gk
i 1 k Ÿi
Ò
Õ2 ATi B R
Ó
Õ
Ô W
0,
if code is not assigned
Pi G j
G j Ëk Ÿi Hki Pk Œ
2
for user j
Power
relieve
Reduce
distortion
by increasing
power
200
1200
1100
150
B
Initialization
A
100
1000
Reduce
distortion
by assigning
a code
Dsum (MSE)
P
900
800
N
50
j 1
0
min Ë D j
Ti , aij
Ò N
Õ Ë aij }1, aij ´{0,1}, i,
Õj1
C
Õ
s.t.Ó Psum Ë Pi }Pmax ,
i 1
Õ
C
ÕR 0 }r R a T }R P , j
Ë
j
j
ij i
j
Õ
i 1
Ô
Balanced Resource Allocation
Power Convergence Curve
700
Distortion Convergence Cruve
0
10
20
30
C'
40
50
600
70
60
Number of Code in use
code constraint
Power and Distortion vs the number of assigned codes
User1
User2
60
Power constraint
40
35
1200
45
40
1000
35
30
30
0
20
40
60
80
25
100
0
20
Frame Index
40
60
80
100
Frame Index
User3
User4
60
60
Proposed
Greedy
55
50
45
40
30
30
25
25
40
60
Frame Index
80
100
400
40
35
20
600
45
35
0
800
Proposed
Greedy
55
50
where aij the indicator that represents whether code i is assigned to
user j, Ti and Pi the corresponding channel coding rate and power of
for code i, Pmax is the maximal power provided in the system, Rpj
and R0j are the maximal and minimal FGS rate for each video
frame.
Proposed
Greedy
50
45
25
1400
Proposed
Greedy
55
50
Rate constraint
Distortion v.s. No. of Users
60
Proposed
Greedy
55
Dsum (MSE)
P
B ase La ye r
PSNR (dB)
I
PSNR (dB)
P
Psum (Watts)
P
1300
PSNR (dB)
P
B a se L aye r
1400
250
PSNR (dB)
I
™ There are N users and C codes in this system. We need
to determine:
a) how many codes are assigned to each user,
b) the channel coding rates, transmitted power for each
code
™ We formulate the problem as follows:
A'
200
0
20
40
60
80
Frame Index
PSNR results for user 1 to user 4
100
0
4
6
8
10
12
Number of users
Performance comparison
14
16