The document details the challenges and solutions of adaptive video streaming over wireless networks, particularly focusing on bandwidth limitations, quality of service, and packet loss. It outlines various methodologies for media delivery adaptation, including layered encoding, prioritization of packets, and real-time video adaptation techniques within a wireless mesh network framework. Experimental results and implementation strategies using ns-2 simulation tools are also discussed to enhance video streaming performance over WLAN and WMN environments.

1. DEPT. OF INFO. & COMM., GIST
Adaptive Video Streaming over
Wireless LAN with ns-2
Ph.D Candidate Hayoung Yoon
hyyoon@nm.gist.ac.kr
Networked Media Laboratory
Dept. of Information & Communications
Gwangju Institute of Science & Technology
NS-2 단기강좌 (2010. 11)

2. DEPT. OF INFO. & COMM., GIST
Agenda
Network Video Streaming Overview
NS-2 Video Streaming Simulation Fra
mework
Case Study: Cross-layered Optimizati
on
March 4, 2020, Page 2

3. DEPT. OF INFO. & COMM., GIST
Network Video Streaming Overview
March 4, 2020, Page 3

4. DEPT. OF INFO. & COMM., GIST
Mesh routers
Emerging Video Streaming Services over
Wireless/Mobile Networks
WLAN
access
point
< WLAN-based
A/V Home Network >
< Indoor Building
with mobile WLAN nodes>
Video
Servers
Over-provisioned
Wired Network
Media
Gateway
< Wireless Mesh Network
(WMN) Backbone>
access
point
End-to-End Quality of Video Applications, such as
Live/stored Video Broadcasting and Video on Demand,
over WLAN/WMN needs to be considered

5. DEPT. OF INFO. & COMM., GIST
Challenges in Wireless Media Delivery
Scarce and limited bandwidth compared to wired environment
Time-varying delay (and jitter) that depends on channel contention
and others
Fluctuating and bursty packet loss due to the fading/shadowing of
wireless channel and channel contention
Different QoS requirements for different types of media
Need unequal error control and priority-based scheduling schemes for
different types of media
Mobile variations including the handoff (transient loss and
disruption)
Complexity limitations due to power consumption of wireless
terminals
Low performance with traditional transport-layer protocols
Heterogeneity: Need to design an efficient transcoding with proxy
caching mechanism
Along with Security related issues

6. DEPT. OF INFO. & COMM., GIST
Media Delivery–Adaptation & Support
(Wireless)
Error Control
Media
Synchroni-
zation
Universal
Media
Access
(Proxy/Trans)
Congestion
(Rate, Flow)
Control
Dynamic
Network
Adaptation
Framework
Robust and
Scalable
Layered
Media
Representation
(Compressed
and
Prioritized) Network
Mobility
Support
Effective
Transport &
Protocol
Support
Network
Multicast
Support
Network QoS
Support
Other M/W
Support
(security
and others)
Monitoring
Adaptation

7. DEPT. OF INFO. & COMM., GIST
Wired/Wireless
Networks
Layered Video Encoding Receiver/
User
Network
Adaptation
Network Adaptation &
Prioritized Packetization
Video
Pre-
process-
ing
R-D
Analysis
Layered
en-
coding
Target
Minimum
Buffer Size
(Receiver
Constraint)
Target
Minimum
Bandwidth
(Network
Constraint)
Frame
Complexity
(Quality
Constraint)
Constant
Quality
Rate
Control
(Source
Rate/Error
Resilience)
(only if
applicable)
Prioritized
Packeti-
zation
Layered
RPI
Network
Monitoring
&
Feedback
Handling Application Feedback
Estimated
Available
Bandwidth,
Loss/Delay
Network Feedback
R-D /
Corruption
Model
Network Feedback (end-to-end)
Network
Adaptation
(Network
Filtering)
Media Delivery – Network Adaptation
Network
Adaptation
(Network
Rate/Loss/
Delay)
Network
Adaptation
(Receiver /
User
Adaptation)
Corrup-
tion
Analysis

8. DEPT. OF INFO. & COMM., GIST
Media Coding & Prioritized Packetization:
Possible Options
Transport
packet
with layered
priority,
timestamp, …
Parsing
Transport-
aware
packetizatio
n
I
0
I
0
I0 P1
P1
P1 B2
B2
packs
I0
I0
P
1
B
2
P
1
P1
B
2
Video packets
audio
Ring
buffer
Audio packets
audio
control
Control packets
I
0
Target
APP
( IM 1 )
MP-4 file
Parser
Object
Scheduler
Controller
NetworkInterface
DAI
NetworkInterface
Priority
Manager
DMIF Service
Manager
Data stream
Control Message
Server Part
Client Part
 Frame-based Prioritization
 Picture Coding Type : I, P, B
 Object-based Prioritization
 MPEG-4 Object
Elementary Stream(ES) based
Prioritization
Description Stream, Audio Stream,
Video Stream, …
 Layered RPI (Relative Priority Index)
for scalable (or layered) media stream
o RLI (Relative Loss-priority Index): from loss
propagation effect
o RDI (Relative delay-priority index):
application’s delay context
 Can be simplified and generalized for general
applications (e.g., prioritization for
immersive media data with A/V/G/Haptics)

9. DEPT. OF INFO. & COMM., GIST
Network-adaptive Layered Media
Streaming
Cellular Network
Internet
Domain A
Domain B
Domain C
Streaming Media Server
Wireless LAN
Mobile PC Mobile PC
Gateway
Base Layer (Layer 0)
Enhancement Layer 1 (Layer 1)
Enhancement Layer 2 (Layer 2)
Priority:
P(B) > P(E1) > P(E2) > … > P(EN)

10. DEPT. OF INFO. & COMM., GIST
Network-Adaptive Video Streaming over
WMN - Framework (2007-)
Internet
video
streams
Access pointMesh routers
< WMN Backbone> < WLAN>
Video Server
WMN gateway
Video
receiver
Real-time
parsing &
prioritized
packetization
Intermediate node QoS control
playout
Playout
buffering
Gateway architecture Video receiver architectureIntermediate node architecture
Packet
dropping
for rate
adaptation
Wireless
channel
monitoring
Packet
discarding
Network
monitoring
(multiple flow)
Cross-layer design
 Extension of the Network-Adaptive Streaming Framework in WLAN into Hop-
by-Hop Framework in WMNs  In each intermediate node, video adaptation
and monitoring functionalities are added
This part is approximately
implemented in present version

11. DEPT. OF INFO. & COMM., GIST
Network-Adaptive Video Streaming over
WMN – Intermediate node
 Intermediate Node Agent Implementation
 User Space: Video Adaptation module
 Kernel Space
 Maintaining per-flow state table
 Loss rate monitoring of video flow
 Interaction with User Space by using
IOCTL
Per-flow State Management
flow
identity
tx_succe
tx_try
flow
identity
tx_succe
tx_try
KernelSpaceUserSpace
MACinterfacequeue
IEEE 802.11
(madwifi-ng)
Observe
“tx_try”
demuxer
Intermedia Hop-drop agent IOCTL
IOCTL
Queryloss-rate
loss_rate=
1-tx_succ/tx_try
Observe
“tx_succ”
demuxer
traffictraffic
Noticeloss-rate
Video adaptation module
S RN1 Np
Intermediate
node agent
IEEE 802.11a-based
MAC & PHY
Static routing
Transport layer (UDP)
Intermediate
node agent
IEEE 802.11a-based
MAC & PHY
Static routing
Transport layer (UDP)
RTP packet
buffer
RTP packet
buffer
 Video adaptation functionality by agent
 RTP packet buffering
 Priority-based packet dropping
 Interaction with MAC & PHY
Interaction
[ Intermediate Node Agent Implementation Architecture ]

12. DEPT. OF INFO. & COMM., GIST
Experimental Results: WMN Testbed
 Deployed in GIST DIC 2nd floor
 1 Gateway (N1), 6 Intermediate nodes (N2~N7)
 IEEE 802.11a-based
 Single Interface
 Single video streaming service on single path
 N1 -> N2 -> N3 -> N4 -> N5 -> N6 -> video
receiver using static routing
 Background traffic (intra/inter-flow)
N1 (gateway)
N2
KOREN
N3
N4
N5
N6
N7
video receiver
video traffic
background traffic
Time(s)
0 50 100 150 200 250
Bitrate
0.0
5.0e+5
1.0e+6
1.5e+6
2.0e+6
2.5e+6
[ Background traffic characteristic: 2Mbps Pareto ]

13. DEPT. OF INFO. & COMM., GIST
 Temporal scalability of experimental video stream
 Clip length: 2 minutes
 GOP: IBBPBB, 30fps, 4Mbps
 4 Temporal layers (l1, l2, l3, l4)
 Rate profile of each temporal layer
 l1: 1.52Mbps, l2: 0.86Mbps, l3: 0.8Mbps, l4: 0.8Mbps
 Frame rate profile of each temporal layer
 l1: 5fps, l2: 5fps, l3: 10fps, l4: 10fps
I0 B1 B2 P3 B5 B6 Original GOP
I0
B1
B2
P3
B5
B6
l1: Base layer
l2
l3
l4
Enhancement
layers
< Temporal layering of experimental video stream>
Experimental Video & Competitive
Schemes
 Competitive Schemes
 NO_ADAPT: No adaptive streaming
 E2E_ADAPT: Network-adaptive streaming with end-to-end monitoring (See Appendix A.3)
 HOP_ADAPT: Proposed scheme
* Adaptation algorithm used in HOP_ADAPT is exactly same as the algorithm used in E2E_ADAPT for
fair performance comparison

14. DEPT. OF INFO. & COMM., GIST
Experimental Results
 Experimental Condition: N4 -> N3 background flow of 2Mbps Pareto Traffic
[ Video throughput measured at each node ]
NO_ADAPT E2E_ADAPT HOP_ADAPT
[ Received packet ratio for every video frame ] [ Accumulated Variance of Playout Discontinuity ]

15. DEPT. OF INFO. & COMM., GIST
NS-2 Video Streaming Simulation
Framework
March 4, 2020, Page 15

16. DEPT. OF INFO. & COMM., GIST
Emulator
Network Video Streaming
March 4, 2020, Page 16
Reduced transfer bitrate by compression
MPEG or H.26X
Transferred bit-stream may suffer loss, delay, or
jitter in the network
Not all frames are reconstructed successfully
1 2 N
Original video frames
Network
Video
Encoder
Video
Decoder
Video
bit-stream
1 2 N
Reconstructed
video frames
Video
bit-stream
……
…

17. DEPT. OF INFO. & COMM., GIST
Video Trace-based Simulation
Framework
Generate bit-stream
Map bits to a packet (packetization)
Map received packets and generate received bit-stream
Evaluate the quality of received video frames with respect to the originals
March 4, 2020, Page 17
Network
Simulator
Video Trace
Generator
Video Stream
Reconstructor
0 1 N…
Original video frames
Video
Encoder
Error-resilient
Video Decoder
Received video frames
0 1 N…
Video
bit-stream

18. DEPT. OF INFO. & COMM., GIST
B2B1
Video Trace Generation - Example
March 4, 2020, Page 18
Panasonic HD CAM Frame rate: 30 Frames/sec
Data rate: 19.2Mbits/sec (CBR I:B:P=8:8:4 Mbits )
GOP structure: IBBPBB (380 Pkts/GOP)
I B2B1P
200 msec
0 1 151 152 228…
I-frame: 152 pkts
189…
B-frame: 38 pkts
Packet Size: 1350 bytes
303…
P-frame: 76 pkts
… …
…
Encoded
Video Frames
(Bit-stream)
Generated
Packet sequence
(video trace)
379 …
GOP: group of pictures

19. DEPT. OF INFO. & COMM., GIST
Reconstruction of Received Frames
Convert sequence ID of packets to the encoded frames information
March 4, 2020, Page 19
PPGPacketFrame
PPG
Packet
GOP
IDLOC
ID
ID
mod




PPG: pkts/GOP
For each reception of GOP, reconstruct the IBBPBB frames
regarding the dependency of those frames
B2B1I B2B1P I
GOP0 GOP1
How is the priority relationship
among I,B, and P frames?

20. DEPT. OF INFO. & COMM., GIST
Performance Evaluation Methods (1)
March 4, 2020, Page 20
Quality
measure of
reconstructed
video
Objective Subjective
Per-frame-based
computation
Discontinuity
computation
Surveying QoE
Hybrid
approach
QoE: Quality of Experience
—Taxonomy—

21. DEPT. OF INFO. & COMM., GIST
Performance Evaluation Methods (2)
PSNR (peak-to-peak signal to noise
ratio) or PER (packet loss rate)
Measure
March 4, 2020, Page 21
– Per-frame-based computation –
Transferred Received
Frame ID
PSNR
Algo. 1
Algo. 2
PCI (Playout continuity index) Measure
– Discontinuity computation –
Transferred
Playout
PCI
Algo. 1 Algo. 2
time
time
…
…
Ex)
Ex)
Discontinuity

22. DEPT. OF INFO. & COMM., GIST
Performance Evaluation Methods (3)
March 4, 2020, Page 22
– Hybrid-approach –
time
Received Frames
time
Received Frames – Corrupted Frames
Discontinuity for
corrupted frames
Discontinuity for
corrupted frames
Discontinuity for
transmission delay
Pause TimemePlayout ti
Pause Time
PCI

1
Expressed over (0,1)
The higher the better quality
0.95 is normally regarded to target
performance

23. DEPT. OF INFO. & COMM., GIST
What will be followed…
Case studies
Video-rate adaptation with cross-layer channel monitoring
Contents in general
Duplication and modification of existing NS-2 modules
Relay information between two objects by “Packet Stamping”
Link two objects using the ::command method
Share information using static data structure/object (for global sync.)
Contents in specific
Video trace-based simulation
Runtime measurement of IEEE 802.11 WLAN traffic statistics
Evaluation of simulation output
March 4, 2020, Page 23

24. DEPT. OF INFO. & COMM., GIST
Case Study: Cross-layered
Optimization
March 4, 2020, Page 24

25. DEPT. OF INFO. & COMM., GIST
Network-Adaptive HD Video Streaming over WLAN: Priority-based
Video Rate Control with Cross-Layered Monitoring
March 4, 2020, Page 25
IEEE 802.11a WLAN
Real-time Parsing
& Prioritized
Packetization (RTP)
Network Adaptation Manager
Priority-based
frame dropping /
Layer-based Rate
Adaptation
RTP packets RTP packets
MAC layer loss rate,
MAC layer buffer overflow rate,
PHY transmission rate
PHY
MAC
19.2Mbps
HD video stream
CLO-based Channel
Monitoring
Streaming Server Architecture
HDD
Stored or Live HD
MPEG-2 TS
TS packets
End-to-end feedback packet
(RTP packet loss rate, average jitter)
drop stage
Video
Player
RTP
monitoring &
Feedback
Priority of RTP packets
Streaming Server with MADWiFi-ng
Mobile Streaming Client
Streaming Client Architecture
SHPARK@CL07

26. DEPT. OF INFO. & COMM., GIST
How Does it Work?
An amount of received video stream is NOT changing whether with
or without rate-adaptation
BUT, received contents is different if rate-adaptation works
Random loss Vs. priority-based rate-control
Drop less-important data at the sender side!
Enhance perceptual quality of received video stream!
March 4, 2020, Page 26
Streaming without rate-adaptation
Available channel resource (does God kno
Streaming with rate-adaptati
time
resource

27. DEPT. OF INFO. & COMM., GIST
NS-2 Implementation Block Diagram
March 4, 2020, Page 27
MAC
Streaming
Receiver
Streaming
Sender
IFQ
PHY
Channel
Monitoring
MAC
IFQ
PHY
Wireless Channel
Available
Channel
Time
Available
Channel
Time
Measurement
tools/tfragen_mp.cc
tools/trafgen_mp.h
tools/video_traffic.cc
agt/udp.cc
agt/udp.h
mac/mac-802_11a.cc
mac/mac-802_11a.h
mac/ch_mon_oop.cc
mac/ch_mon_oop.h

28. DEPT. OF INFO. & COMM., GIST
Vanilla ver. NS-2 Implementation Review
PHY/MAC
Single PHY rate (1Mbps by default)
Received packets are dropped only for the collision
Routing
AODV, TORA, or DSR in the “Vanilla” version of NS2
IEEE 802.11 Infrastructure mode (no routing required)
We adopted “NORT” (NO RouTing) from
http://www.winlab.rutgers.edu/~zhibinwu/html/ns_fading_error.html
Application
No application can dynamically adjust the priority of packets (in
IP header)
March 4, 2020, Page 28

29. DEPT. OF INFO. & COMM., GIST
IEEE 802.11a Implementation Choices?(1
)
From the scratch?
From the design to the new module implementation to the existin
g NS-2 structure
Frame headers, timers, backoff handling, and protocol specific rout
ines
Hard to evaluate how the new module is working correctly?
Time consuming
Keep the original IEEE 802.11 module in NS-2
Modification of existing IEEE 802.11 module?
Adding new data-rate support (6, 9, 12, 18, 24, 36, 48, and 54 M
bsp) and different IFS (inter-frame spacing) while keep all the oth
er routines
Easy and fast!
Loss of the original IEEE 802.11 module in NS-2March 4, 2020, Page 29

30. DEPT. OF INFO. & COMM., GIST
IEEE 802.11a Implementation Choices?(2
)
Is there any way to keep original IEEE 802.11 while we
modify the existing codes?
Duplication and modification of existing IEEE 802.11 module
March 4, 2020, Page 30
Ex) 802.11  802.11a
1. cd ns-2.29/mac/
2. sed ‘s/Mac802_11/Mac802_11a/g’ mac-802_11.cc > tmp.cc
3. sed ‘s/Mac802_11/Mac802_11a/g’ mac-802_11.h > tmp.h
4. sed ‘s/PHY_MIB/PHY11A_MIB/g’ tmp.cc > tmp-1.cc
5. sed ‘s/PHY_MIB/PHY11A_MIB/g’ tmp.h > tmp-1.h
6. sed ‘s/MAC_MIB/MAC11A_MIB/g’ tmp-1.cc > tmp-2.cc
7. sed ‘s/MAC_MIB/MAC11A_MIB/g’ tmp-1.h > tmp-2.h
8. sed ‘s/mac802_11/mac802_11a/g’ tmp-2.cc > mac-802_11a.cc
9. sed ‘s/mac802_11/mac802_11a/g’ tmp-2.h > mac-802_11a.h
# change all the class name “Mac802_11” to “Mac802_11a” in the
original file mac-802_11.cc and write to the new file mac-802_11a.cc
# mac-timer.cc (h) also need to be changed accordingly

31. DEPT. OF INFO. & COMM., GIST
IEEE 802.11a Implementation Choices?(3
)
March 4, 2020, Page 31
Ex) 802.11  802.11a
1. cd ns-2.29/
2. vim Makefile.in
3. edit: OBJ_CC=… mac/ll.o mac/mac-802_11.o mac/mac-802_11a.o …
1. cd ns-2.29/tcl/lib
2. vim ns-default.tcl
3. edit: duplicate all Mac/802_11 parameters and rename them to Mac/802_11a as
below:
# modify Makefile.in to compile 802.11a module
# ns-default.tcl
Mac/802_11 set CWMin_ 31
…
Mac/802_11 set LongRetryLimit_ 4 ;# retransmissions
Mac/802_11a set CWMin_ 31
…

32. DEPT. OF INFO. & COMM., GIST
IEEE 802.11a Implementation Choices?(4
)
March 4, 2020, Page 32
Ex) 802.11  802.11a
1. cd ns-2.29/tcl/lan
2. vim ns-mac.tcl
3. add new is-class function for Mac/802_11a
# ns-mac.tcl
…
if [TclObject is-class Mac/802_11] {
Mac/802_11 set delay_ 64us
…
Mac/802_11 set rtxRetryLimit_ 1
}
if [TclObject is-class Mac/802_11a] {
Mac/802_11a set delay_ 64us
…
Mac/802_11a set rtxRetryLimit_ 1
}
4. cd ns-2.29/
5. make clean; ./configure; make
# Compile NS-2 with new 802_11a
module
6. cd ns-2.29/tcl/ex/
7. run simple-wireless.tcl with 802_11
and 802_11a and compare the output
trace files
# simple-wireless.tcl
…
set val(mac) Mac/802_11
# simple-wireless.tcl
…
set val(mac) Mac/802_11a
 With Mac/802_11
 With Mac/802_11a

33. DEPT. OF INFO. & COMM., GIST
IEEE 802.11a PHY Implementation (1)
Transfer packet at higher data-rate is simply done
Assign transmission time to the HDR_CMN.txtime_
But, how can we deliver transmitted data-rate information to the receiv
er?
Let’s put that information to the NS-2 Packet structure (discuss later)
March 4, 2020, Page 33
Line # function: sendData (Packet *p) in mac-802_11
a.cc
1176 hdr_cmn* ch = HDR_CMN(p);
… …
1204 current_mode = rate_to_mode(LA->get_rate());
… …
1209
ch->txtime() = txtime(ch->size(),
PHY11a_dataRate_[current_mode]);
– Packet transmission at different rate –
802.11a MAC
::PHY11a_dataRate_[1]
.
.
.
::PHY11a_dataRate_[8]
6Mbps
54Mbps

34. DEPT. OF INFO. & COMM., GIST
IEEE 802.11a PHY Implementation (2)
Put a “stamp” to each Packet sent to
carry data-rate and SINR information
The “stamp” must be copied when th
e original packet is copied!
“Stamping” is very useful to deliver t
he information at one node to the oth
ers
Avoid to use a global storage (static)
March 4, 2020, Page 34
Line
#
class: Packet (Packet *p) in packet.h
346 class Packet : public Event {
… …
407 ChannelStamp chinfo_;
… …
622 inline Packet* Packet::copy() const{
623 Packet* p = alloc();
… …
630 p->chinfo_.init(&chinfo_);
632 …}
– Relay data-rate and SINR information –
ChannelStamp Data-rate
SINR
Packet

35. DEPT. OF INFO. & COMM., GIST March 4, 2020, Page 35
IEEE 802.11a PHY Implementation (3)
See “mac/per_table_11a.h”
to find PER (packet error
rate) for the specific SINR
and length of received
packets [Qiao@TOMC02]
Decision of packet drop is
done at MAC (mac/mac-
802_11a.cc)
Line # function: recv_timer() in mac-802_11a.cc
1578 double snr = pktRx_->chinfo_.getSigdB();
1579 int mod = pktRx_->chinfo_.getModulationMode();
1580 int Psize = ch->size();
1581 double per_ = per.get_per(Psize, mod, snr);
1582 bool result = per.decision(per_);
… …
1588 if(result == false) {
… …
1609 discard(pktRx_, "SNR");
1612 … }
– Packet drop control –
0 5 10 15 20 25 30
0
5
10
15
20
25
30
35
Effectivegoodput(Mbps)
Effective Goodput (MSDU=1500 Bytes)
Eav
/No
(dB)
Mode8
Mode7
Mode4
Mode6
Mode5
Mode3
Mode2
Mode1

36. DEPT. OF INFO. & COMM., GIST
Other Components in 802.11a MAC
Gilbert-Eliot channel model
Auto-rate Fallback
Measurement of MAC traffic statisti
cs
RX/TX success
RX/TX failure
Channel time monitoring module
March 4, 2020, Page 36
GE_model
802.11a MAC
ARF
Measurement
Link_layer_
Monitor_time
mac/ch_model_oop.cc
mac/ch_model_oop.h
mac/link_adaptation_oop.cc
mac/link_adaptation_oop.h
mac/ch_mon_oop.cc
mac/ch_mon_oop.h
mac/ch_mon_oop.cc
mac/ch_mon_oop.h
.
.
.
Only AP has

37. DEPT. OF INFO. & COMM., GIST
Measurement Routine (1)
AP periodically
measures traffic
statistics within WLAN
March 4, 2020, Page 37
AP
STA STA
STA STA
802.11a MAC
.
.
.
::sendACK
::recvACK
::recv_timer
::RetransmitDATA
Detect TX success
Detect TX failure

38. DEPT. OF INFO. & COMM., GIST March 4, 2020, Page 38
Measurement Routine (2)
Line # function: sendACK() in mac-802_11a.cc
1146 if(AP) {
1147 double rate = get_mod_rate(pktRx_);
1148 int rate_mode = rate_to_mode(rate);
1149 hdr_cmn* ch_rx = HDR_CMN(pktRx_);
1150 int plen = ch_rx->size() + phymib_.getPLCPhdrLen();
1151 measurement_[rate_mode]->success(1, plen);
1152 }
– TX success measurement –
Line # function: recvACK() in mac-802_11a.cc
1888 if(AP) {
1889 struct hdr_cmn *ch_tx = HDR_CMN(pktTx_);
1890 measurement_[current_mode]->success(1, ch_tx->size());
1891 }
Measurement
::success
::retransmit_data
.
.
.

39. DEPT. OF INFO. & COMM., GIST March 4, 2020, Page 39
Measurement Routine (3)
Line
#
function: recv_timer() in mac-802_11a.cc
1497 if(rx_state_ == MAC_COLL) {
… …
1508
measurement_[rate_mode]->retransmission_data(1,ch->size())
;
… …
1520 if( ch->error() ) {
… …
1530
measurement_[rate_mode]->retransmission_data(1,ch->size())
;
– TX failure measurement –
Line
#
function: RetransmitData() in mac-802_11a.cc
1300 if(AP) {
1301
measurement_[rate_mode]->retransmission_data(1,ch->size())
;
… …
Measurement
::success
::retransmit_data
.
.
.

40. DEPT. OF INFO. & COMM., GIST
Available Resource Computation
Periodically calculate the available
wireless channel resource
Available = Period – Utilized – Overhead
Initialize measurement information
March 4, 2020, Page 40
Line
#
function: est_timeout () in mac-802_11a.
cc
1497 if(AP){
… est_timer.resched(1.0);
1508 llmt.update_capacity(measurement_, 1.0);
… for(int i=0;i < MAX_N_PHY_RATE; i++)
1520 measurement_[i]->init();
… …
1540 upper_layer[i]->do_adaptation();
Link_layer_
Monitor_time
::updata_capacity()
::get_available()
::get_used()
::get_overhead()
SHPARK@CL07
Hayoung@CL07
goto-adaptation

41. DEPT. OF INFO. & COMM., GIST
Streaming Server Implementation (1)
Packet priority assignment
Recall frame decoding dependency
I > P > B1 = B2
Video trace (ds_level.txt)
Packet sequence & priority trace for a
GOP
Streaming server (video_traffic.c
c) initialize prio[seq] array using
ds_level.txtMarch 4, 2020, Page 41
0:4
1:4
…
151:4
152:1
153:1
…
189:1
190:2
191:2
…
227:2
228:3
229:3
…
303:3
304:1
305:1
…
341:1
342:2
343:2
…
379:2
ds_level.txt
I
B
B
P
B
B
Streaming server
video_traffic.cc trafgen_mp.cc trafgen_mp.h
cbr_traffic.cc trafgen.cc trafgen.h

42. DEPT. OF INFO. & COMM., GIST
Streaming Server Implementation (2)
March 4, 2020, Page 42
TX timer expire
send(seq, prio[seq])
prio[seq] > drop
get_next_interval
reschedule TX timer
No
Yes
B2B1I B2B1P I
B2I B2P I
I P I
I I
drop=0
drop=1
drop=2
drop=3
Adaptation routine should decide “drop” dynamically

43. DEPT. OF INFO. & COMM., GIST
Application-MAC Linkage (1)
March 4, 2020, Page 43
– TCL script –
Line
#
video_ex6.tcl
130 set BS(0) [$ns node 1.0.0]
… …
138 [$BS(0) set mac_(0)] setAP
… …
181 set app($i) [new Application/Traffic/VIDEO]
… …
190 $app($i) add-mac [$BS(0) set mac_(0)]
… …
192 [$BS(0) set mac_(0)] add-upperlayer-object $app($i)

44. DEPT. OF INFO. & COMM., GIST
Application-MAC Linkage (2)
March 4, 2020, Page 44
Line # function: command() in mac-802_11a.cc
397 int Mac802_11a::command(int argc, const char*const* argv){
398 if (argc == 3) {
399 if( strcmp(argv[1], "add-upperlayer-object") == 0) {
400 TrafficGenerator_mp *temp = (TrafficGenerator_mp*) TclObject::lookup(argv[2]);
401 upper_layer[temp->dest_mac_id] = temp;
... …
– C++ implementation –
Line # function: command() in trafgen_mp.cc
66 int TrafficGenerator_mp::command(int argc, const char*const* argv){
67 if (argc == 3) {
68 if( strcmp(argv[1], "add-mac") == 0) {
69 mac = (MAC_CLASS*) TclObject::lookup(argv[2]);
70 return TCL_OK;
... …

45. DEPT. OF INFO. & COMM., GIST
Run Simulation
Run
ns video_ex6.tcl [seed] [sim_time
]
Option
with dynamic adaptation
$app($i) dynamic-adaptation 1
without dynamic adaptation
$app($i) dynamic-adaptation 0
Output
frame_recovery_time.tr
March 4, 2020, Page 45
AP
STASTA STA
paretopareto
video
I frame: 0 recovered at 2.092667
P frame: 3 recovered at 2.177218
B frame: 1 recovered at 2.177218
B frame: 2 recovered at 2.177218
I frame: 6 recovered at 2.282833
…
frame_recovery_time.tr
- Topology -

46. DEPT. OF INFO. & COMM., GIST
Performance Evaluation (1)
Measure
Inter-frame-distance
Time difference between consecutive recovered frame
Average-distance
Average of Inter-frame-distance
Smoothness
RMS (Inter-frame-distance, Average-distacne)
March 4, 2020, Page 46
0 543 8 1110
time
RMS: root-mean-square
Inter-frame-
distance[3]
… Inter-frame-
distance[5]
Inter-frame-
distance[8]
Inter-frame-
distance[10]
Inter-frame-
distance[11]

47. DEPT. OF INFO. & COMM., GIST
Performance Evaluation (2)
The larger the smoothne
ss,
the lower the QoS!March 4, 2020, Page 47
#AWK code Run: ./cal_smooth.awk frame-recovery-tim
e.tr
#!/usr/bin/awk -f
BEGIN{
}
{
recovery[$3+1] = 1
recovery_T[$3+1] = $6
last_frame=$3+1
}
END{
for (i=2;i<last_frame+1;i++) {
if (recovery[i]==1) {
inter_recovery_time[i]=
recovery_T[i] - recovery_T[i-lost_fr
ame_len-1]
loss_frame_len=0
acc=acc+inter_recovery_time[i]
cnt++
} else {
loss_fram_len++
}
}
average_distance = acc/cnt
acc=0;cnt=0
for (i=2;i<last_frame+1;i++) {
if(recovery[i]==1) {
acc=acc +
((average_distance – inter_recovery_time[i]
)^2.0)^0.5
cnt++
}
}
printf(“smoothness: %f Avg. dist.: %fn”,
acc/cnt, average_distance);
}

48. DEPT. OF INFO. & COMM., GIST
Thank you!
Send Inquiry to
hyyoon@nm.gist.ac.kr
Visit our homepage to download NS-2 source codes
http://nm.gist.ac.kr/twiki/bin/view/Main/HayoungYoon
Gwangju Institute of
Science & Technology