TCP-real: improving real-time capabilities of TCP over heterogeneous networks

ABSTRACT

We present a TCP-compatible and -friendly protocol which abolishes thr ee major shortfalls of TCP for reliable multimedia applications over heterogeneous networks: (i) ineffective bandwidth utilization, (ii) unnecessary congestion-oriented responses to wireless link errors (e.g., fading channels) and operations (e.g. handoffs), and (iii) wasteful window adjustments over asymmetric, low-bandwidth reverse paths. We propose TCP-Real, a high-throughput transport protocol that minimizes transmission-rate gaps, thereby enabling better performance and reasonable playback timers. In TCP-Real, the receiver decides with better accuracy about the appropriate size of the congestion window. Slow Start and timeout adjustments are used whenever congestion avoidance fails; however, rate and timeout adjustments are cancelled whenever the receiving rate indicates sufficient availability of bandwidth. We detail the protocol design and we report significant improvement on the performance of the protocol with time-constrained traffic, wireless link errors and asymmetric paths.

REFERENCES

• 1: M. Allman, V. Paxson, W. Stevens, "TCP Congestion Control", RFC2581, April 1999
• 2: W. Feng, D. Kandlur, S. Saha and K. Shin, "Understanding TCP Dynamics in an Integrated Service Internet", NOSSDAV '97, May 1997.
• 3: L.S. Brakmo and L.L. Peterson, "TCP Vegas: End to End Congestion Avoidance on a Global Internet", IEEE Journal on Selected Areas in Communications, 13(8):1465-1480, Oct 1995
• 4: Vassilios Tsaoussidis , Hussein Badr , Rohit Verma, Wave and Wait Protocol (WWP): An Energy-Saving Transport Protocol for Mobile IP-Devices, Proceedings of the Seventh Annual International Conference on Network Protocols, p.301, October 31-November 03, 1999
• 5: Vassilis Tsaoussidis , A. Lahanas , C. Zhang, The Wave & Probe Communication Mechanisms, The Journal of Supercomputing, v.20 n.2, p.115-135, September 2001 [doi>10.1023/A:1011122500883]
• 6: Hari Balakrishnan , Venkata N. Padmanabhan , Randy H. Katz, The effects of asymmetry on TCP performance, Proceedings of the 3rd annual ACM/IEEE international conference on Mobile computing and networking, p.77-89, September 26-30, 1997, Budapest, Hungary [doi>10.1145/262116.262134]
• 7: Sergey Gorinsky , Harrick Vin, Additive Increase Appears Inferior, University of Texas at Austin, Austin, TX, 2000
• 8: The X-Kernel: http://www.princeton.edu/xkernel
• 9: S. Floyd, and T. Henderson, "The NewReno Modification to TCP's Fast Recovery Algorithm", RFC2582, April 1999

INDEX TERMS

Primary Classification:
  C. Computer Systems Organization
  C.2 COMPUTER-COMMUNICATION NETWORKS

Additional Classification:
  C. Computer Systems Organization
  C.2 COMPUTER-COMMUNICATION NETWORKS

General Terms:
Reliability, Theory