1. Cross Layer Optimization Techniques 9 May 2008 Department of Electrical Engineering & Computer Science EECS 983 Class Project Ramya Naidu Sarvesh Kumar.V Asifuddin Mohammad Piyush Upadhyay

2. 9 May 2008Cross Layer Optimization Techniques2 Cross Layer Optimization Techniques Outline Introduction UDP segment Size adaptation Knobs and Dials Simulation Framework TCP segment size adaptation –Issues –Effect of ARQ on TCP performance –Effect of FEC/ARQ on TCP performance

3. 9 May 2008Cross Layer Optimization Techniques3 Cross Layer Optimization Techniques Introduction Cross Layer Optimization [CLO]: –An approach that coordinates protocol behavior at different layers with a goal to maximize the overall performance [4] –Knobs and Dials Dials pass information from lower to higher layer Knobs pass info from higher to lower layer CLO Technique considered: –Transport layer with Physical Layer interaction –Segment size with BER

4. 9 May 2008Cross Layer Optimization Techniques4 Cross Layer Optimization Techniques Outline Introduction UDP segment Size adaptation Knobs and Dials simulation framework TCP segment size adaptation –Issues –Effect of ARQ on TCP performance –Effect of ARQ/FEC on TCP performance Hardware Implementation

5. 9 May 2008Cross Layer Optimization Techniques5 Cross Layer Optimization Techniques UDP Segment Size adaptation Adapt UDP segment size as BER of the link changes Initial Analysis of effect on throughput Simulation parameters –Number of nodes 2 –CBR/UDP –Rate 1Mbps –Link Capacity 1Mbps –Simulation time 50s –Error Model Uniform

6. 9 May 2008Cross Layer Optimization Techniques6 Cross Layer Optimization Techniques UDP Segment Size adaptation

7. 9 May 2008Cross Layer Optimization Techniques Cross Layer Optimization Techniques UDP Segment Size adaptation Initial Analysis with UDP lead to two directions Building the knobs and dials simulation framework Study the complications when extending this scheme to TCP

8. 9 May 2008Cross Layer Optimization Techniques8 Cross Layer Optimization Techniques Outline Introduction UDP segment Size adaptation Knobs and Dials Simulation Framework TCP segment size adaptation –Issues –Effect of ARQ on TCP performance –Effect of ARQ/FEC on TCP performance Hardware Implementation

9. Knobs and Dials Simulation Framework

10. Step 1: Node 1 Sends packets to Node 2 9 May 2008Cross Layer Optimization Techniques

11. Knobs and Dials Simulation Framework 9 May 2008Cross Layer Optimization Techniques Step 2: Computer BER from received packets and update the dial matrix

12. Knobs and Dials Simulation Framework 9 May 2008Cross Layer Optimization Techniques Step 3: Write the BER from dial matrix to the dial packet (Out of band signaling)

13. Knobs and Dials Simulation Framework Dial Packet format used Choice of Inband Vs Out of band signalling has to be made Dial Packet format should be decided if out of band signaling is used 9 May 2008Cross Layer Optimization Techniques

14. Knobs and Dials Simulation Framework Step 4: Read the BER value from the dial packet and write it to the dial matrix of node 1 9 May 2008Cross Layer Optimization Techniques

15. Knobs and Dials Simulation Framework Step 5: Read the BER value from the dial matrix of N1 and compute the new segment size 9 May 2008Cross Layer Optimization Techniques

16. Knobs and Dials Simulation Framework Step 6: Write the new segment size to the knob matrix (An unused knob) and transmit with this size 9 May 2008Cross Layer Optimization Techniques

17. Simulation Challenges Creating a new signaling protocol for out of band signaling Building knob and dial hashes at each node Accessing packet headers Obtaining a Tcl handle to C++ class variables to enable per packet processing Per packet processing 9 May 2008Cross Layer Optimization Techniques

18. Knobs and Dials Simulation Framework Issues to be addressed: –Complexity at each node –Overhead due to extra signaling (Out of band) –Loss of Signaling packets –RTT of the link –Changes to framework in case of multi-hop network with multiple interfaces at nodes 9 May 2008Cross Layer Optimization Techniques

19. 9 May 2008Cross Layer Optimization Techniques19 Cross Layer Optimization Techniques Outline Introduction UDP segment Size adaptation Knobs and Dials Simulation Framework TCP segment size adaptation –Issues –Effect of ARQ on TCP performance –Effect of ARQ/FEC on TCP performance Hardware Implementation

20. 9 May 2008Cross Layer Optimization Techniques20 Cross Layer Optimization Techniques TCP Segment Size adaptation TCP with Link layer reliability –Effect of ARQ on TCP –Effect of FEC/ARQ on TCP TCP without Link layer reliability

21. 9 May 2008Cross Layer Optimization Techniques21 Cross Layer Optimization Techniques Effect of ARQ on TCP ARQ persistency and TCP RTO –ARQ with low persistency does not improve TCP throughput –High persistency improves TCP performance [2] –Problems of ARQ with high persistency [1]

22. 9 May 2008Cross Layer Optimization Techniques22 Cross Layer Optimization Techniques Effect of ARQ/FEC on TCP Throughput improvement is more significant due to ARQ than due to FEC in an ARQ/FEC scheme [2]

23. 9 May 2008Cross Layer Optimization Techniques23 Cross Layer Optimization Techniques TCP without link layer reliability LL retransmission does not always improve TCP throughput [1] This motivates the study of segment size adaptation

24. Simulation Challenges Implementing FEC in ns2 Hacking the ns2 error model code 9 May 2008Cross Layer Optimization Techniques

25. Future Work Extending the simulations to multi-hop scenarios Study the impacts of cross-layering signaling Extending the framework for other knobs and dials 9 May 2008Cross Layer Optimization Techniques

26. 9 May 2008Cross Layer Optimization Techniques26 Cross Layer Optimization Techniques Outline Introduction UDP segment Size adaptation TCP segment size adaptation –Issues –Effect of ARQ on TCP performance –Effect of ARQ/FEC on TCP performance Hardware Implementation

27. 9 May 2008Cross Layer Optimization Techniques27 References [1] Kim Hyogon, Changhoon Han. "Reducing TCP response time in face of wireless uplink losses." IEEE VTC'01 1(2001): 262-266. [2] A.Chockalingam, Michael Zorzi. "Wireless TCP Performance with Link Layer FEC/ARQ." IEEE ICC'99 2(1999): 1212-1216. [3] Jin-Hee Choi, Jin-Ghoo Choi,Chuck Yoo. "Dynamic Segment Size Adjustment for TCP performance in cellular networks." ICEE'05 (2005): 95-96. [4] A.Warrier,L.Le and I.Rhee. “Cross-Layer Optimization made practical”. Broadnets 2007(Invited paper) [5] Gary J. Minden, Joseph B. Evans, Leon Searl, Daniel DePardo, Victor R. Petty, Rakesh Rajbanshi, Jordan Guffey, Qi Chen, Timothy Newman, Frederick Weidling, Dinesh Datla, Brett Barker, Megan Peck, Brian Cordill, Alexander M. Wyglinski, and Arvin Agah, “KUAR: A Flexible Software-Defined Radio Development Platform,” Second IEEE Symposium on New Frontiers in Dynamic Spectrum Access Networks (Dublin, Ireland), April 2007.

28. References [6]Minden, G.J. Evans, J.B. Searl, L.S. DePardo, D. Rajbanshi, R. Guffey, J. Qi Chen Newman, T.R. Petty, V.R. Weidling, F. Peck, M. Cordill, B. Datla, D. Barker, B. Agah, A. ” COGNITIVE RADIOS FOR DYNAMIC SPECTRUM ACCESS - An Agile Radio for Wireless Innovation” IEEE communication Magazine, May 2005, Vol. 45,issue 5. 9 May 2008Cross Layer Optimization Techniques