Analytical Model of Hop-to-End based Network-Adaptive FEC scheme over Multi-hop Wireless Networks Koh Choi Networked Media Laboratory Dept. of Information & Communications Gwangju Institute of Science & Technology (GIST) 1

2 Introduction(1/2)  Video streaming in Multi-hop Wireless Networks Burst packet loss, long delay Decreased streaming quality  FEC-based error control Reduce packet loss and support streaming quality Limitation of traditional FEC scheme  End-to-End(E2E) FEC: self-induced congestion problem, long packet delay  Hop-by-Hop(HbH) FEC: per-hop overhead, additional complexity

3 Introduction(2/2)  Proposed Multi-hop FEC scheme Combine E2E and HbH FEC scheme Partitioning, overlay …  Hop-to-End FEC scheme Multi-hop FEC scheme Adaptive control from hop to end concept Minimize packet loss and considering delay-constraint  Reduce less delay than E2E FEC and HbH FEC To apply Hop-to-End FEC scheme, it need adaptation policy over multi-hop wireless networks from monitored results. Also, it support guideline based on adaptation policy. In this presentation, design adaptation policy through analytical modeling aspect as coordinator to control adaptive FEC control.

4 Problem Definition  Objective Minimize recovered packet loss (P (n,k,x) )  Constraints Delay constraint: D (n,k,x) ≤ D C Bandwidth limitation: B fec(n) ≤ B max (B req(n-k) ≤ B avail ) Fixed sending rate of streaming data: R Fixed original data: k  Monitoring parameter P e2e, P hop(x), P h2e(x), D e2e, D hop(x), D h2e(x) Monitoring main component: P hop(x), D hop(x)  Control parameter FEC symbol size n, FEC Operation Point

5 System Model(1/2) End-to-End FEC Hop-to-End FEC Only consider narrow bandwidth in streaming path.

6 System Model(2/2) End-to-End Hop-to-End Additional delay factor from increasing hop count and data rate (offline measure)

7 AM-H2E(TBD) Modeling Input (k, P hop(x), D hop(x) ) Output (n, x) Original data k is fixed. Based on above formulation, find (n, x).

8 Notation -P e2e : End-to-End(E2E) packet loss -P hop(x) : Hop-by-Hop(HbH) packet loss -P h2e(x) : Hop-to-End(H2E) packet loss -P r-e2e(n,k) : Recovered E2E packet loss -P r-hop(n,k,x) : Recovered HbH packet loss -P r-h2e(n,k,x) : Recovered H2E packet loss -P (n,k,x) : Total recovered packet loss -D e2e : E2E transmission delay -D hop(x) : HbH transmission delay -D h2e(x) : H2E transmission delay -D r-e2e(n,k) : Recovered E2E transmission delay -D r-hop(n,k,x) : Recovered HbH transmission delay -D r-h2e(n,k,x) : Recovered H2E transmission delay -D (n,k,x) : Total recovered transmission delay -R (k) : Original sending rate -R (n) : Sending rate with redundant data -P: Packet size -M: Number of nodes -L: Number of hops -B max : Maximum Bandwidth -B avail : Available Bandwidth (B max – B data ) -B data(k) : Original data bandwidth -B redun(n-k) : FEC bandwidth from redundant data -B fec(n,k) : Overall bandwidth(B req + B data ) -FOP(x): FEC Operation Point -D c : Delay constraint -P c : Covered packet loss -ET fec(n,k) : Encoding time -DT fec(n,k) : Decoding time -D R(n) : Transmission delay from sending rate

9 Implementation progress  Enable FEC code based on RS Using NASTE+ FEC code Modified FEC operation (exclude unnecessary operation)  Define interface Monitoring parameter, module and enqueue/dequeue interface