Transport Protocols for Wireless Networks CMPE 293 - Spring 2001 Marcelo M. de Carvalho.

Slides:



Advertisements
Similar presentations
A Comparison of Mechanisms for Improving TCP Performance over Wireless Links Published In IEEE/ACM TRANSACTIONS ON NETWORKING, VOL.5 NO.6,DECEMBER 1997.
Advertisements

A feedback–based scheme for improving TCP performance in Ad Hoc Wireless Networks Group : Manish Mehta Aditya Barve.
1 Improving TCP Performance over Mobile Networks HALA ELAARAG Stetson University Speaker : Aron ACM Computing Surveys 2002.
Improving TCP over Wireless by Selectively Protecting Packet Transmissions Carla F. Chiasserini Michele Garetto Michela Meo Dipartimento di Elettronica.
A study of Cross layer work of University of Trento folk A ResiliNet Group Presentation Sarvesh Kumar Varatharajan.
Improving TCP Performance over Mobile Ad Hoc Networks by Exploiting Cross- Layer Information Awareness Xin Yu Department Of Computer Science New York University,
Improving TCP Performance over MANETs by Exploiting Cross-Layer Information Awareness Xin Yu NYU Presented by: David Choffnes.
Improving TCP/IP Performance Over Wireless Networks Authors: Hari Balakrishnan, Srinivasan Seshan, Elan Amir and Randy H. Katz Jerome Mitchell Resilient.
TCP in Wireless Ad Hoc Networks
6/3/ Improving TCP Performance over Mobile Ad Hoc Networks by Exploiting Cross-Layer Information Awareness CS495 – Spring 2005 Northwestern University.
CMPE 257: Wireless and Mobile Networking
Internet Networking Spring 2003 Tutorial 12 Limited Transmit RFC 3042 Long Thin Networks RFC 2757.
Ruy de Oliveira December 05, 2001
TCP over ad hoc networks Ad Hoc Networks will have to be interfaced with the Internet. As such backward compatibility is a big issue. One might expect.
CS 268: Wireless Transport Protocols Kevin Lai Feb 13, 2002.
Improving TCP Performance over Ad-hoc Network 11/28/2000 Xuanming Dong, Duke Lee, and Jin Wang Course Project for EE228A --- Fall 2000 (Professor Jean.
TCP for wireless links Dario Maggiorini
1 ATP: A Reliable Transport Protocol for Ad-hoc Networks Sundaresan, Anantharam, Hseih, Sivakumar.
TCP in Heterogeneous Network Md. Ehtesamul Haque # P.
Reliable Transport Layers in Wireless Networks Mark Perillo Electrical and Computer Engineering.
TCP performance in Wireless Networks Ehsan Hamadani July 2004.
CMPE 257 Spring CMPE 257: Wireless and Mobile Networking Spring 2005 E2E Protocols (point-to-point)
1 K. Salah Module 6.1: TCP Flow and Congestion Control Connection establishment & Termination Flow Control Congestion Control QoS.
1 A Comparison of Mechanisms for Improving TCP Performance over Wireless Links Course : CS898T Instructor : Dr.Chang - Swapna Sunkara.
TCP in a wireless environment CS 215 Winter 2001 TCP and wireless handoff TCP Snoop for wireless loss protection TCP and MAC layer interaction.
Wireless TCP February 22, 2002 © 2002 Yongguang Zhang CS 395T - Mobile Computing and Wireless Networks Department of Computer SciencesTHE UNIVERSITY OF.
CIS 725 Wireless networks. Low bandwidth High error rates.
CS640: Introduction to Computer Networks Aditya Akella Lecture 22 - Wireless Networking.
Spring 2000Nitin BahadurAdvanced Computer Networks A Comparison of Mechanisms for Improving TCP Performance over Wireless Links By: Hari B., Venkata P.
Qian Zhang Department of Computer Science HKUST Advanced Topics in Next- Generation Wireless Networks Transport Protocols in Ad hoc Networks.
10/1/2015 9:14 PM1 TCP in Mobile Ad-hoc Networks ─ Split TCP CSE 6590.
Mobile Communications: Mobile Transport Layer Mobile Communications Chapter 10: Mobile Transport Layer  Motivation  TCP-mechanisms  Indirect TCP  Snooping.
Asstt. Professor Adeel Akram.  Motivation  TCP mechanisms  Indirect TCP  Snooping TCP  Mobile TCP  Fast retransmit/recovery  Transmission freezing.
Improving TCP Performance over Mobile Networks Zahra Imanimehr Rahele Salari.
Prof. Dr.-Ing. Jochen Schiller, SS029.1 Mobile Communications Chapter 9: Mobile Transport Layer  Motivation  TCP-mechanisms.
Lecture 11 Mobile Networks: TCP in Wireless Networks Wireless and Mobile Systems Design.
TCP PERFORMANCE OVER AD HOC NETWORKS Presented by Vishwanee Raghoonundun Assisted by Maheshwarnath Behary MSc Computer Networks Middlesex University.
Wireless TCP Prasun Dewan Department of Computer Science University of North Carolina
1 Impact of transmission errors on TCP performance (Nitin Vaidya)
Obile etworking M-TCP : TCP for Mobile Cellular Networks Kevin Brown and Suresh Singh Department of Computer Science Univ. of South Carolina.
1 Transport Protocols (continued) Relates to Lab 5. UDP and TCP.
Transport over Wireless Networks Myungchul Kim
Dynamic Source Routing (DSR) Sandeep Gupta M.Tech - WCC.
1 TCP III - Error Control TCP Error Control. 2 ARQ Error Control Two types of errors: –Lost packets –Damaged packets Most Error Control techniques are.
ECE 695 Sp 2006 Jim Catt TCP Functions TCP is a connection oriented protocol Primary functions  TCP sets up and maintains end-to-end connection between.
Wireless TCP. References r Hari Balakrishnan, Venkat Padmanabhan, Srinivasan Seshan and Randy H. Katz, " A Comparison of Mechanisms for Improving TCP.
TCP-Cognizant Adaptive Forward Error Correction in Wireless Networks
Transport layer protocols The objectives of a transport layer protocol include the setting up of an end-to-end connection, end-to- end delivery of data.
Improving TCP Performance over Wireless Networks
Challenges to Reliable Data Transport Over Heterogeneous Wireless Networks.
15-744: Computer Networking L-18 Mobile Transport and Applications.
TCP on Wireless Ad Hoc Networks CS 218 Oct 22, 2003 TCP overview Ad hoc TCP : mobility, route failures and timeout TCP and MAC interaction study TCP fairness.
Outline Wireless introduction Wireless cellular (GSM, CDMA, UMTS) Wireless LANs, MAC layer Wireless Ad hoc networks – routing: proactive routing, on-demand.
Transport Protocols for Wireless Ad Hoc Networks 1.
TCP OVER ADHOC NETWORK. TCP Basics TCP (Transmission Control Protocol) was designed to provide reliable end-to-end delivery of data over unreliable networks.
MOBILE TCP.
Ασύρματες και Κινητές Επικοινωνίες Ενότητα # 11: Mobile Transport Layer Διδάσκων: Βασίλειος Σύρης Τμήμα: Πληροφορικής.
ACN: Transport Protocols in Mobile Environments 1 Improving the Performance of Reliable Transport Protocols in Mobile Computing Environments Ramon Caceres.
Computer Networking Lecture 18 – TCP over Wireless.
2005/12/14 1 Improving TCP Performance over Mobile Ad Hoc Networks by Exploiting Cross-Layer Information Awareness Xin Yu Department of Computer Science.
TCP/IP1 Address Resolution Protocol Internet uses IP address to recognize a computer. But IP address needs to be translated to physical address (NIC).
1 Ad-hoc Transport Layer Protocol (ATCP) EECS 4215.
Mobile Transport Layer  Motivation  TCP-mechanisms  Indirect TCP  Snooping TCP  Mobile TCP  Fast retransmit/recovery  Transmission freezing  Selective.
TCP over Wireless PROF. MICHAEL TSAI 2016/6/3. TCP Congestion Control (TCP Tahoe) Only ACK correctly received packets Congestion Window Size: Maximum.
Ad-hoc Transport Layer Protocol (ATCP)
TCP - Part II Relates to Lab 5. This is an extended module that covers TCP flow control, congestion control, and error control in TCP.
IT351: Mobile & Wireless Computing
TCP in Wireless Ad-hoc Networks
TCP for Wireless Networks
Impact of transmission errors on TCP performance
Presentation transcript:

Transport Protocols for Wireless Networks CMPE Spring 2001 Marcelo M. de Carvalho

Outline Overview: –Transport Protocols & TCP –Limitations & Problems in Wireless TCP for Single-Hop Networks –Improving the Performance for TCP: classes of protocols TCP for Multi-Hop Networks –TCP for MANETs

Traditional Transport Protocols Reliable transport protocols have been tuned for networks composed of wired links and stationary hosts. They adapt to prevailing end-to-end delay conditions throughout the life of a connection; Main Assumption: Increases in delay are interpreted as packet losses caused by congestion.

Sources of Errors in Wireless Links Pauses due to handoff between cells; Packet losses due to futile transmissions: mobile host out of reach of other transceivers (little or no overlap between cells); Packet losses due to transmission errors in wireless links.

How does TCP work? TCP continually measure how long acknowledgments take to return; If –Retransmit packet; –Initiate congestion control procedure: Drop transmission window size; Activate slow-start algorithm; Reset retransmission timer to a backoff interval that doubles with each consecutive time-out.

Improving the Performance of TCP MSS 1MSS 2 SH MH Cell 1 Cell 2

Smooth Handoff Cellular networks should strive to provide smooth handoffs in order to eliminate packet losses during cell crossings. No overlaps are also good!!! –High aggregate bandwidth: adjacent cells can use the same portion of the spectrum; –Support for low-powered mobile receivers; –Accurate location information

Retransmission Timers Long pauses are partly due to inaccurate retransmission timers. TCP implementations have coarse timers (300- to 500-millisecond resolution); Small timeout: –multiple reductions of the slow-start threshold; –multiple backoffs of the retransmission timer; –multiple retransmissions before the routes become consistent.

Fast Retransmissions IDEA: Resume communication immediately after handoffs complete, without waiting for a retransmission timeout. Modern TCPs: activated when a transmitter receives triplicate acknowledgments from a receiver; Once a greeting arrives at the MH, TCP invokes the fast retransmission procedure.

Comparision of Mechanisms End-to-end protocols Split-connection protocols Link-layer protocols Hybrid protocols

End-to-end Protocols Sender is aware of the existence of wireless hops. Selective Acknowledgments (SACKs): sender can recover from multiple packet losses without resorting to a coarse timeout. Explicit Loss Notification (ELFN): the sender can distinguish between congestion and other forms of losses.

Split-connection Protocols Goal: to hide any non-congestion-related losses from the TCP sender. TCP connection is split between a sender and receiver into two separate connections at the base station: –TCP connection over wired link; –Specialized protocol over wireless link.

I-TCP: Indirect TCP MH MSR FH MH = Mobile Host MSR = Mobile Support Router FH = Fixed Host I-TCPTCP

TCP/IP in Mobile Environment Main reason for throughput degradation: –Loss of TCP segments during cell crossovers, especially with non-overlapped cells. Effects: –Lost segments trigger exponential back off and congestion control at the transmitting host. –Congestion recovery phase may last for several seconds.

Indirect Protocol Different flow control and congestion control for wireless and wired links; Separate transport protocol supports disconnections, moves and other wireless related features; MSR manages much of the overhead; Faster reaction to mobility due to proximity between MSR and MH.

I-TCP Basics move MSR-2 FH MH MH socket MH MH socket MSR-1 MSR1 mhsocket MSR1 fhsocket MSR2 fhsocket MSR2 mhsocket FH socket I-TCP Handoff Regular TCP Wireless TCP

Link-layer Protocols Two main classes: –Error correction using techniques such as Forward Error Correction; –Retransmission of lost packets in response to automatic repeat request (ARQ) messages. Tuned to the characteristics of the wireless link.

Hybrid Protocols: The Snoop Prootocol An agent monitors every packet and maintains a cache of TCP segments that have not yet been acknowledged. Packet loss is detected by the arrival of a small number of duplicate acks or by a local timeout. The agent retransmits the lost packet and suppresses the duplicate acks.

Observations TCP-aware link-layer protocol with selective acknowledgments performs the best; Split-connection approaches is not a requirement for good performance. Selective acknowledgment is very useful in lossy links, especially for burst losses. Explicit Loss Notification is worth to try.

TCP Performance over MANETs Goals: I –nvestigate the impact of link failures due to mobility on TCP performance; –Define expected throughput; –Enhance throughput with Explicity Link Failure Notification (ELFN).

Simulation Environment NS Network Simulator; TCP-Reno over IP on an wireless network; Dynamic Source Routing (DSR) Protocol; BSD ARP protocol (to resolve IP addresses to MAC addresses); 30 nodes in a 1500 X 300 meter area moving according to the random waypoint mobility model.

Expected Throughput t i = duration of time for which the shortest path from the sender to receiver contains i hops. T i = throughput obtained over a linear chain using i hops.

TCP with ELFN Implementation: –Use ICMP message as a notice to the TCP sender; –If the routing protocol sends a route failure message to the sender, then the notice can be piggy-backed on it. TCP’s response: disable congestion control mechanism until route has been restored.

Observations Routing protocol has a significant impact on TCP performance (cache and propagation of stale routes); More aggressive cache management protocols are needed.