Smooth Video Handoff over Wireless Networks

Smooth Video Handoff over Wireless Networks

Yi Pan and Tatsuya Suda{ypan,suda}@ics.uci.eduSchool of Information and

Computer ScienceUniversity of California, Irvine

Outline Motivation Proposed scheme Simulation and demo Conclusion

Motivation Current handoff techniques:

Single mobile IP binding may cause packet loss during handoff

Switching data transmission path is dangerous for active sessions

Handoff causes transmission rate reduction Due to disparity of available bandwidth in different

cells, the transmission rate in the previous cell may not be proper to avoid congestion in the new cell

Network mobility support can not handle this problem

Motivation Multimedia applications need a

smooth handoff provides Reduced packet loss Continuous streaming Congestion avoidance in new cell Smooth adaptation of video quality to

various bandwidth

Our Proposal Use multiple paths to reach a single mobile

node Assign different mobile IP addresses (COAs) to

different paths reaching a single mobile node Exploit different amounts of bandwidth on

multiple paths to a single mobile node To reduce or prevent a packet loss due to hand

off To increase throughput for the mobile node

Basic Ideas Preventing a packet loss due to handoff

Sending a packet on multiple paths during handoff reduces loss

When a packet is lost on one path due to handoff, the packet is still available on the other paths

InternetBase Station2

Base Station1

Mobile Node

Wireless Gateway

Home Agent

Corresponding NodeCOA1

Path1 to COA1

Mobile Node COA1 Lifetime 1


COA1 is registered to Home Agent and Corresponding Node and Path1 is used to send packets to COA1

Basic Ideas Preventing a loss due to handoff


When a packet is lost on one path due to handoff, the packet is still available on the other path


Base Station1

Mobile Node

Wireless Gateway

Home Agent

Corresponding Node

COA1

COA2

Path1 to COA1

Path2 to COA2

COA2 Lifetime 2



COA2 Lifetime 2

Path2 to COA2 and path1 to COA1 are both used to multicast data packets to the mobile node

Basic Ideas Preventing a loss due to handoff


When a packet is lost on one path due to handoff, the packet is still available on the other paths


Base Station1

Mobile Node

Wireless Gateway

Home Agent

Corresponding Node

COA2



Path2 to COA2

While the mobile node moves out of the transmission range of base station1, it loses COA1 but the data packets are continuously available through path2 to COA2

Basic Ideas Exploit different amounts of bandwidth

Multi layer video transmission on multiple paths during handoff


Base Station1

Mobile Node

Wireless Gateway

Home Agent

Corresponding Node

COA1

COA2

Path2 to COA2

Path1 to COA1

COA2 Lifetime 2



COA2 Lifetime 2

Data belong to Basic LayerData belong to Enhanced Layer

Background Techniques Networking layer technique

Multi-homing Mobile IP

Transport layer technique TCP Friendly Rate Control (TFRC)

Application layer technique Source Adaptive Multi-layer encoder

Background Techniques Network layer technique

Multi-homing One host gets multiple IP addresses Schemes to support multi-homing

DHCP protocol in IPv4 IPv6 address auto-configuration and multi-

homing

Background Techniques DHCP protocol in IPv4

DHCP servers in the network can provide dynamic COA addresses for the mobile node

By sending requests and getting COAs for multiple interfaces, the mobile node can acquire multiple COAs

Multi-homed Host

Base Station 1 Base Station 2

Network Prefix 1 Network Prefix 2

DHCP request DHCP request

Background Techniques DHCP protocol in IPv4

DHCP servers in the network can provide dynamic COA addresses for the mobile node

By sending requests and getting COAs for multiple interfaces, the mobile node can acquire multiple COAs

Multi-homed Host


Network Prefix 1 Network Prefix 2

IPv4 Addr1 IPv4 Addr2

Background Techniques IPv6 address auto-configuration and multi-

homing By suffixing the network prefix from the

routers with host’s MAC address, multiple IPv6 COA addresses can be achieved

Multi-homed Host


IPv6 Network Prefix 1 IPv6 Network Prefix 2

Host MAC Addr

IPv6 Addr1 = {IPv6 Network Prefix 1||Host MAC Addr}

IPv6 Addr2 = {IPv6 Network Prefix 2||Host MAC Addr}

Background Techniques Mobile IP

Basic Mobile IP

Internet

Base Station1

Mobile Node

Wireless Gateway

Home Agent


BindingUpd(COA1)

BindingUpd(COA1)


Basic Mobile IP

Internet

Base Station1

Mobile Node

Wireless Gateway

Home Agent


Mobile Node COA

1

Packet

Lifetime1


Basic Mobile IP

Internet

Base Station1

Mobile Node

Wireless Gateway

Home Agent


Path1 to COA1

COA

1

Packet

COA

1

Packet

Mobile Node COA

1

Lifetime1


Options used Simultaneous binding (to support multi-

homing)


Base Station1

Mobile Node

Wireless Gateway

Home Agent

Corresponding Node

COA1

COA2

COA2 Lifetime 2


BindingUpd(COA1)

BindingUpd(COA1)

Background Techniques Route optimization


Base Station1

Mobile Node

Wireless Gateway

Home Agent

Corresponding Node

COA1

COA2

Packet

COA2 Lifetime 2




Base Station1

Mobile Node

Wireless Gateway

Home Agent

Corresponding Node

COA1

COA2

BindingUpd(COA1,COA2)

COA2 Lifetime 2




Base Station1

Mobile Node

Wireless Gateway

Home Agent

Corresponding Node

COA1

COA2

PacketCOA1

PacketCOA1

PacketCOA1

COA2 Lifetime 2


COA2 Lifetime 2


Background Techniques Transport layer technique

TCP Friendly Rate Control (TFRC) We use TFRC end-to-end rate control

algorithm instead of TCP To avoid the high fluctuation of transmission

rate resulting from the saw tooth shaped TCP window dynamics

Background Techniques TFRC calculates the transmission rate

using an equation below

Packet loss rate p is calculated through a short history of observed packet loss, through a weighted averaging method

)*321(**8/*3*3/*2 2nominalpppTpRTT

MTUR

rto

k

iiii LLwp

11/1

Nominal bandwidth

TFRC throughputTCP throughput

0

0.6

1.2

1.8

2.4 3

3.6

4.2

4.8

5.4 6

6.6

7.2

7.8

8.4 9

9.6

10

.2

10

.8

11

.4 12

12

.6

13

.2

13

.8

14

.4 15

15

.6

16

.2

16

.8

17

.4 18

18

.6

19

.2

19

.8

20

.4 21

21

.6

22

.2

22

.8

23

.4 24

24

.6

Background Techniques Features of TFRC during congestion avoidance

phase: Fairness to TCP

It achieves a long run throughput equal to the nominal bandwidth that a TCP session will occupy under the same congestion status

Stable transmission rate It maintains a sustainable rate against intermittent

packet around the nominal bandwidth. Thus, the fluctuation of transmission rate due to

the saw-tooth shaped TCP window dynamics is largely reduced

Quick reaction to congestion It reacts to persistent packet losses by forcing a

reduction of transmission rate over several round trip time

Background Techniques Application layer technique

Source adaptive multi-layer encoder for stream media

Multi-layer stream media Multiple encoding layers are applied in the

encoder Base layer packets contain most critical data

for the decoder Enhanced layer packets provide additional

information to increase the quality of stream media

Background Techniques Multi-Layered Video

Multi-LayerEncoder

RawVideo

Base layer

Enhancement layer

Base LayerBase +

Enhancement Layers

Technical Background Source adaptation multi-layer encoder

Source adaptive multi-layer encoder takes ri, bi, εi as input parameters to video layer i

ri is the transmission rate for video layer i bi is the buffered bits of video layer i to be sent to

the network εi is the encoding error rate

System Architecture Multi-path transport protocol

design

Components in the Architecture Path Management Module

Exist in transport layer at both ends Keep a record of all available paths Assign rate control module for each available

path Rate Control Module

A pair of rate control modules exist at both ends for each available path

Perform end-to-end feedback-based rate control on each path

Components in the Architecture Multi-path Distributor

Exist at the sender side Calculate and report the number of

video layers and target encoding rates for video layers to the application (video encoder)

Assign appropriate paths to each video layer and send the video packets through multiple paths

Components in the Architecture Multi-path Collector

Exist at the receiver side Receive video packets from multiple

paths and reorder the buffered video streams

Deliver the video streams to application (video decoder)

Simulation Settings Simulation Scenario:

Home AgentHome Agent

Corresponding Node (source of video traffic)

Corresponding Node (source of video traffic)

Mobile Node

(receiver of video traffic)

Mobile Node

(receiver of video traffic)

Intermediate RoutersIntermediate Routers

Wireless GatewaysWireless Gateways

Distance between neighboring base stations = 500 meters

Distance between neighboring base stations = 500 meters

Base station cell coverage radius = 300 meters with link speed = 11 Mbps

Base station cell coverage radius = 300 meters with link speed = 11 Mbps

Background Traffic Nodes

Background Traffic Nodes

Base StationsBase Stations

Different Average background traffic volume in different base stations are explored in simulation

Different Average background traffic volume in different base stations are explored in simulation

Simulation Settings Compared handoff schemes:

Single path schemes with single mobile IP binding: No forwarding: no local packet forwarding for mobile

nodes is performed among base stations Basic Mobile IP technique

Forwarding: packets are relayed from the old base station to the new base station when the mobile node enters the new cell

Represent network layer mobility enhancement techniques that repair the packet loss on a broken path for an active session

Multi-path handoff scheme Handoff with multiple mobile IP bindings

TFRC rate control is employed in all schemes to achieve smooth rate for stream media application

Simulation Results Results and observations:

Video throughput when the mobile node moves from high bandwidth cell to low bandwidth cell

Multi-path Video Throughput

0

1000000

2000000

3000000

4000000

5000000

6000000

0 3 6 9

12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60 63 66Time (sec)

Bit

Rat

e (b

ps)

Total Video Throughput Base Layer Throughput

when mobile node is in a high bandwidth cell, high bandwidth is used to transmit base layer video

when mobile node is in a high bandwidth cell, high bandwidth is used to transmit base layer video

During handoff, base layer rate reduces to the rate equal to the bandwidth in the low bandwidth cell, and enhancement layer video is transmitted at the rate equal to the difference between high and low bandwidth in the two cells

During handoff, base layer rate reduces to the rate equal to the bandwidth in the low bandwidth cell, and enhancement layer video is transmitted at the rate equal to the difference between high and low bandwidth in the two cells

when mobile node is in a low bandwidth cell, low bandwidth is used to transmit base layer video

when mobile node is in a low bandwidth cell, low bandwidth is used to transmit base layer video

Simulation Results Improved throughput

Multi-path handoff scheme keeps the video throughput high but adjust the base video layer to the lower rate

Multi-path handoff scheme keeps the video throughput high but adjust the base video layer to the lower rate

With different available bandwidth in the new cellWith different available bandwidth in the new cell

Simulation Results Reduced packet loss

Multi-path handoff scheme keeps the packet loss ratio low. Base layer is protected with near-to-zero loss ratio

Multi-path handoff scheme keeps the packet loss ratio low. Base layer is protected with near-to-zero loss ratio

With different available bandwidth in the new cellWith different available bandwidth in the new cell

Simulation Results Improved goodput

With protection of base layer, the goodput is improved in terms of smooth video frame rate

Video Demo Demo scenario Received Video

Raw video at the sender

Video Demo

Raw video at the sender

Received video stream

Single path w/o ForwardingSingle path w/o Forwarding

Single path w/ ForwardingSingle path w/ Forwarding

Multi-path HandoffMulti-path Handoff

Conclusion Contributions

Integrate multi-layer encoding, multi-homed mobile nodes through a multi-path transport protocol

Provide smooth end-to-end stream media handoff with wide range of bandwidth changes

Conclusion Merits of multi-path handoff

Less packet loss during handoff duplicated packets are transmitted through

multiple paths during handoff Quality improvement

Because more important data (e.g., base layer video) is transmitted over multiple paths during handoff

Minimum deployment in network Only the end systems are needed

http://netresearch.ics.uci.edu/ypan/MPATH_strm Thank you!!!

Documents

Smooth Video Handoff over Wireless Networks