Dis iscrete Water Fil illi ling Mult lti-Path Packet Scheduli ling IEEE ISIT 2020 Arno Schneuwly * Derya Malak Muriel Médard Oracle Labs Rensselaer Polytechnic Institute Massachusetts Institute of Technology arno.schneuwly@oracle.com malakd@rpi.edu medard@mit.edu 1 * The presented work had been implemented when Arno Schneuwly was a visiting student at MIT and MSc student at EPFL.
Seamless Handover Proble lem Connected to WiFi… WiFi Download 1 Download running … 2 3 4 Podcast App 5 Packet The example download starts over a home wireless connection. 2
Seamless Handover Proble lem Switch to Cellular … Download Interruption Download interrupted … The switch from wireless to cellular causes a download interruption. 3
Seamless Handover Proble lem Cellular Download 1 2 3 5 4 The download resumes and completes over the cellular network connection. 4
Seamless Handover Proble lem: Round Robin MPTCP 2 1 3 4 5 MPTCP faces head-of-line (HOL) blocking and requires packet retransmission for the handover. 5
Seamless Handover Proble lem: MPTCP/NC 5 4 3 2 1 RLNC Through the FEC structure MPTCP/NC mitigates delays caused by retransmission and HOL. 6
Mult lti-Path Point-to to-Poin int Scheme Sender Receiver Bucket of K packets RLNC Coding Vector Coded Packets Z Paths Erasure Vector Cumulative perfect feedback The individual paths are modelled as packet erasure channels (PEC) which transmit DoFs. 7
Example Network of of 4 4 Paths How to allocate the coded packets to the different paths? 8
Mult lti-Path: How to to all llocate the coded packets? • Goal : Transmit K DoFs over Z paths with different loss probabilities. • Loss Vector • Transmissions for 1 DoF • Delivery Time for k j DoFs • In-Order Delivery Time The path with the maximum transmission delay determines the system’s performance. 9
Mutli li-Path: Optimization Proble lem Problem: has no closed form. The optimization problem allocates DoFs. 10
Mutli li-Path: Optimization Proble lem – Simpli lification Apply Jensen’s Inequality to simplify MinDeliv : Applying Jensen’s inequality gives the opimization problem a simple structure. 11
Dis iscrete Water Fil illi ling Mult lti-Path Packet Scheduler Optimal Allocation Vector Minimized Delivery Time Multi-Path Rate DWF balances the allocation of DoFs among the Z paths to minimize the delivery time. 12
Dis iscrete Water Fil illi ling Example No DoFs scheduled. No paths activated. 13
Dis iscrete Water Fil illi ling Example 1 DoF scheduled. Path 1 activated. 2 slots occupied in the path with the longest delay. 14
Dis iscrete Water Fil illi ling Example 2 DoFs scheduled. Paths 1 & 2 activated. 3 slots occupied in the path with the longest delay. 15
Dis iscrete Water Fil illi ling Example 3 DoFs scheduled. Paths 1 & 2 activated. 4 slots occupied in the path with the longest delay. 16
Dis iscrete Water Fil illi ling Example 4 DoFs scheduled. Paths 1, 2 & 3 activated. 4 slots occupied in the path with the longest delay. 17
Dis iscrete Water Fil illi ling Example 5 DoFs scheduled. Paths 1, 2, 3 & 4 activated. 5 slots occupied in the path with the longest delay. 18
Dis iscrete Water Fil illi ling Example 76 DoFs scheduled. Paths 1, 2, 3 & 4 activated. 60 slots occupied in the path with the longest delay. 19
Dis iscrete Water Fil illi ling Example The packets in the network are random linear combinations of the original K packets. 20
Dis iscrete Water Fil illi ling Example: Performance The DWF MP system achieves better rates. 21
Conclusion - Optimization Framework : DWF RLNC-coded MP scheme transmitting a bucket of K packets over Z PEC paths • Further results in this paper : - Delay Sensitivity - Resource Efficiency - Efficient Optimization Algorithms - Upper Bound Solutions (instead of Jensen) Thank you. 22
External Image Sources Slides 2-6: • Wireless Antenna: http://www.clker.com/cliparts/f/f/e/4/12065572121317625675no_hope_Wireless_access_point.svg.hi.png (June 7, 2020) • WiFi Alliance Logo : https://upload.wikimedia.org/wikipedia/commons/f/f8/Wi-FI_Alliance_Logo.png (June 7, 2020) • iPhone : https://www.pikpng.com/pngl/b/247-2473632_ten-screen-space-gray-iphone-x-transparent-background.png (June 7, 2020)
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