An End-to-End Multipath Smooth Handoff Scheme for Stream Media Yi Pan Meejeong Lee Jaime Bae Kim...
-
date post
21-Dec-2015 -
Category
Documents
-
view
216 -
download
0
Transcript of An End-to-End Multipath Smooth Handoff Scheme for Stream Media Yi Pan Meejeong Lee Jaime Bae Kim...
An End-to-End Multipath Smooth Handoff Scheme
for Stream Media
Yi Pan
Meejeong Lee
Jaime Bae Kim
Tatsuya Suda
IEEE Journal On Selected Areas In Communications. Vol. 22, No. 4, May 2004
Introduction
Streaming media are becoming popular in wireless mobile network
Providing smooth handoff between cells is challenging Rerouting packets may results in burst packet
loss Heterogeneous cells bandwidth
Introduction
A number of mobility management techniques have been purposed to provide smooth handoff in homogeneous networks
This paper focus on Smooth handoff of stream media in
heterogeneous best-effort wireless mobile networks
System Architecture
Principles Reduce impact of packet loss
Establishing multiple paths to the mobile node Transmitting duplicate packets (video layers) over
multiple paths Adapt to available bandwidth in new cell
Employing probing techniques to estimate available bandwidth in new cell
Change transmission rate adaptively
System Architecture
Path Management Discover and maintain m
ultiple path between sender and receiver
Make use of Mobile IP options Simultaneous binding
Allow receiver to register multiple COAs (Care-Of-Address)
Route Optimization Allow sender to be inform
ed about receiver’s COAs registrations
System Architecture
Rate Control Estimate available
bandwidth on paths Make use of TCP friendly
rate control (TFRC) Receiver send packet
loss ratio report to sender every RTT
System Architecture
Multipath Distributor Calculate the number of
video layers and bitrates Decide the paths to trans
mit layers Video Layer-Path Adapta
tion (VLPA)
System Architecture
Multipath Distributor Video Layer-Path Adaptation (VLPA)
ri – Cumulative rate from layer 0 (base) to (and including) layer i
rilayer = ri – ri-1
Number of video layers = Number of distinct transmission rates on the paths
ri = ith transmission rates (sorted, ascending) on the paths
System Architecture
Multipath Distributor Video Layer-Path Adaptation (VLPA)
If transmission rates on paths are 1, 2, 2, 4 Mbps Number of layers = 3 r0 = 1Mbps, r1 = 2Mbps, r2 = 4Mbps Layer i is transmitted redundantly through all paths wh
ose transmission rate ≥ ri
VLPA runs periodically (40ms in simulations)
Performance Evaluations
Comparison Schemes Single path without packet forwarding
Packets in transit to old base station is discarded Single path with packet forwarding
Packets in transit to old base station is forwarded to new base station
Proxy-based Proxy located in each base station for transcoding New cell’s proxy retransmit last incomplete video frame Assume a centralized controller to inform proxies about the
available bandwidth in new cell immediately
Performance EvaluationsSimulator OPNET
Coverage radius 300m
Distance between base stations
500m
Wireless link 802.11b 11Mbps
Wireless link BER 10-3 to 10-5
Wired link 155Mbps
Wired link BER 10-12
Wired Propagation Delay 10μs
Packet Size 1024bytes
Mobile node movement Trajectory model
Performance measures are obtained during handoff
Performance Evaluation
MPATH utilize all available paths as soon as enter the node enters overlapped zone
SP_NF, SP_FF and PROXY may not choose to use the link with more available bandwidth due to handoff
Bandwidth estimation by TFRC is slow, so SP_NF and SP_FF are slow in acquiring new available bandwidth
Bandwidth in old cell= 7.8 Mbps
Node speed = 30 mph
RTT = 60 ms
SP_NF:Single Path No Forward
SP_FF:Single Path With Forward
MPATH:Multipath Handoff scheme
PROXY:Proxy-based scheme
Performance Evaluations
All, except PROXY, throughput decrease as RTT increases TFRC rate control relies on end-to-end feedback
9.4Mbps 6.2Mbps
Performance Evaluations
All, except PROXY, throughput decrease as node speed increases Node spends less time in overlapped region TFRC rate control performs end-to-end feedback less often Slower to acquire new available bandwidth
9.4Mbps 6.2Mbps
Performance Evaluations
MPATH does not suffer from rerouting loss Node continues receive p
acket from all base stations
MP_Base (Base layer of MPATH) has near zero loss Redundant transmission i
n all base stations
Performance Evaluations
SP_NF and SP_FF has largest packet loss ratio in most cases
SP_FF significantly reduce rerouting loss, and thus total loss
MP_Base (Base layer of MPATH) has virtually zero packet loss ratio due to redundant transmissions
Performance Evaluations
Frame rate = 25fps Frame with less than 10% packet loss is considered successfully received Small fluctuation in all schemes in (a) as the new cell has larger bandwidth
and, thus, no congestion Large fluctuation in SP_NF and SP_FF in (b) as the new cell has smaller
bandwidth and congestion occurs MPATH shows smooth changes in all case, due to rate control and
redundant transmissions
9.4Mbps 6.2Mbps
Performance Evaluations
Redundant transmissions of packet lower bandwidth efficiency
Different base stations layout affect transmission redundancy
Performance Evaluations
Transmission Efficiency = number of unique packets to total number of transmitted packets
Transmission efficiency decrease as available path increases Largest reduction occurs when all paths have same
bandwidth
Performance Evaluations
Each node is guaranteed to get at least 400kbps Proxy based scheme is used as comparison base MPATH does not significantly impact the number of
mobile nodes supported
Conclusion
Multipath Smooth Handoff Scheme Protect important data (base layer) through redun
dant transmissions on multiple paths Performance is comparable to proxy-based sche
me Overhead is insignificant as size of overlapping ar
ea is limited in practice