Ikawalo

Googled TCP Westwood and TCP Vegas.

Sent an email about changing the topic to sir cedric. :)

read 'The Eifel Algorithm: Making TCP Robust Against Spurious Retransmissions' (2000)
the technique uses timestamp option in the tcp header to eliminate "spurious" retransmissions.

"The sender always stores the timestamp of the first retransmission independent of whether that was triggered by an expiration of the retransmission timer or by the receipt of three consecutive DUPACKs5. In our implementation, we call that timestamp ts_first_rexmit. Then, when the first ACK that acknowledges the retransmission arrives, the sender compares the timestamp of that ACK with ts_first_rexmit. If it is smaller than ts_first_rexmit, this indicates that the retransmission was spurious."

Ikapito

created a ppt presentation about TCP. https://docs.google.com/present/edit?id=0AecHgxabb_zmZGc5Y3doYnFfMzF4YmtmNXJjcA&hl=en
still not talking to my adviser about changing of thesis topic.

started reading High Performance TCP/IP Networking: Concepts, Issues, and Solutions. Mahbub Hassan, Raj Jain (2003)
there are 3 interesting mathematical models in chapter 5 that i can use in my thesis.
Periodic Model -> a simple model that predicts throughput (packet/s ?)
Detailed Packet Loss Model -> a more accurate periodic model.
Stochastic Model with General Loss Process -> a more complex model that uses a new loss process to calculate throughput.

i need to read the math over and over again to understand how the model is built. i think they are relatively easy mathematical models.

Ikaanim

read 'Behavior of TCP-Probing with Hand-offs' (2001). Hand-offs occur (specially in GSM networks)when one mobile node connected on a fix node changes its location where its signal is not covered by the fixed node. The fix node will then "hand-off" its connection to the nearest fixed node that covers the mobile node.

read 'Improving Reliable Transport and Handoff Performance in Cellular Wireless Networks' (1995) -> di kelangan. BOO

read 'Improving TCP/IP Performance over Third Generation Wireless Networks' (2008)
di rin kelangan bano.

read 'Transport Layer Design in Mobile Wireless Networks' (2005)
SCTP is thoroughly discussed here.
in TCP , one notable flavor here is TCP-Peach, yet another probing technique. TCP-peach is for Satellites. So there's no need to read on this.

another important figure is Table 4.2 Comparison of different TCP enhancement schemes.

Ikalima

read 'TCP-Probing: Towards an Error Control Schema with Energy and Throughput Performance Gains' (2000)
this is where i'll start. My protocol and algo is almost like the paper's technique in tcp-probing. i will make a new or modified type of this probing technique. it will be more complicated and my findings must be superior from the old one. i must research extensively on tahoe, reno, new reno. Probing must be an add-on to many tcp flavors.

will integrate randomization and probabilities to determine the nature of error.

will i consider energy efficiency? will i consider tcp-probing on receiver's side?

will i test on many users? will i check fairness, convergence, etc?

must research on testing.

Ikaapat

read 'A Comparison of Mechanisms for Improving TCP Performance over Wireless Links' (1997)
the techniques are divided in 3 types:
1. Link-layer mod
2. Split-connection protocols -> (eg. snoop)no
3. End to end
We will focus only on #3
SACK
SMART -> improved SACK
ELN (explicit loss notification) -> flag on TCP. used for knowing type of error.
ELN with retransmit on first dupack

Ikatlo

Continue reading 'Open Issues on TCP for Mobile Computing'

Error recovery:
Freeze-TCP -> avoids timeouts by sending a ZWA from receiver.
TCP probing :)
TCP Santa Cruz
TCP-Real
DAKS delayed acks
fast retransmission
TCP New Reno
TCP-SACK selective

No interest in proxy-based approaches:
Indirect-TCP
MTCP
Explicit Bad State Notification
WTCP
Snoop

Protocol Strategy
PROBING!
high goodput, energy-efficient

END

Read 'An End-to-End Transport Protocol for Extreme
Wireless Network Environments' (2006)

it extends TCP-sacks technique by incorporating:
ECN -> so the routers/base stations must be ECN enabled
uses FEC (Forward error correction) -> add redundant data into packet.
changing MSS (Maximum segment size) -> cwnd

Ikalawa

1. read 'Analysis of reliable transport layer protocols in wireless networks' (2006)
this is just some report of a random student but its references are OK

keywords:
I-TCP
Snoop-TCP
NS2

basic issues of TCP over wireless networks are mentioned here. I-TCP and Snoop-TCP are 'middleware' apps on TCP, thus not end to end. They buff the packets to increase throughput.

2. read 'Open Issues on TCP for Mobile Computing' (2002/2003)
broad info on problems of TCP over mobile wireless networks

TCP tahoe: slow start, congestion avoidance and fast retramsmit
TCP reno: fast recovery w/ fast retransmit
TCP vegas: good rtt measurements.

Research issues:
detect nature of error -> fading channel, congestion, handoff, burst errors
must be energy-saving due to constrained devices
ECN -> flag in IP
RED -> random early detection.
End-to-end argument -> where to place desired function

Error Detection:
TCP-probing
WTCP -> base station buffs data received
levels of congestion->
"The efficiency of such measurements on the congestion level has two dimensions: how to measure congestion, and where to measure it (i.e., at the sender or the receiver). In the next section we extend the discussion on the latter, since it crucial for the error recovery tactics of TCP. As for the former, whether an estimation of congestion should be based on RTT measurements, on the packet-pair approach, on the wave pattern, or on single probes is an open issue of further research and experimentation."
TCP-Real

Error Recovery:

Una

Time to pick a thesis topic.
i'm interested in topics which are something about:
reliable transfer on mobile ad-hoc networks
reliable transfer on wireless networks
reliable multicast
end to end reliability in wireless networks

the title is something like improving/enhancing end to end reliability in mobile networks.

in wireless mobile networks, packet loss can occur due to weak connection signal and interference. TCP only recognizes packet loss as a result of congestion.

Mobile:
SMS
GPRS
HSDPA
wifi
etc.

=> will research on these.

How to test:
Omnet++
java mobile -> emulator

How to prove that my protocol is correct.
-math!
-tests

As of now, my knowledge is limited to:
tcp stuff
convergence
fairness
rtt
who will initiate retransmits?
ordering? -> bat sa sctp optional

research pa sa tcp variants.
other end to end techniques for reliable transfer
checksum, hash, etc.

Papakialaman pa ba ang underlying networks?
multicast
manets
mesh
routing
gsm