Post on 17-Nov-2020
Hiromi Hirai ( Ochanomizu University )
Total throughput is improved.
It has no negative effect on the others by switching.
We developed a new transmission-control mechanism.
Switching TCP is effective in mobile communication.
Investigate which situation suits for each TCP.
A Study on Transmission-Control Middleware
on Android Terminal in a Wireless LAN Environment
The AP handle a few packets.
The mobile phone can enjoy high speed
networking.
The AP handle a lot of packets.
Each mobile phone is faced with low speed
networking.
Such a situation ・Network traffic is filled with too many packets.
・Additional packets will be lost.
What’s congestion ?
Wired network
is so reliable
Each device avoid
congestion by
independent prediction
We considered a new control
to avoid congestion by
sharing each other’s
communicating condition.
Most of packet
losses take place
In wireless network.
Previous study
Other’s CWND
Own CWND
TCP Log
TcpView A visualization tool for TCP behavior of Android kernel
It parses Kernel Monitor logs and visualizes them.
Extension Exchange each parameters
Visualize other devices’ TCP behavior
Kernel Monitor An existing tool which leaves the log of working TCP.
This is special tool as it is difficult to observe TCP.
It records CWND, the length of socket buffer queue,
error event and which part of source code is executed.
CWND CWND
Experimental behavior
artificial packet loss rate : 2%
TCP-cubic Simple way to predict congestion by packet
losses. When it lost a single packet , it
decreases CWND drastically. It works
conservatively in sending packets.
TCP-original
It is based on TCP-cubic. It works
aggressively. It is effective in high delay
environment(more than 32ms RTT).
CWND is a data sender’s parameter which denotes how many segments it sends for an ACK.
DICOMO2011 Kaori Miki
A Study about Performance Improvement and Analysis of Communication on Android in a Wireless LAN with Kernel Monitor
TIME
TCP-cubic Especially in high packet loss rate
environment, it limits itself too much.
In wireless LAN environment, noise
often slip into the communication.
In wired LAN
High packet loss rate ≒ congestion
In wireless LAN
High packet loss rate ≠ congestion
TCP-original It is improved the demerit of TCP-
cubic. It is optimized for the mobile.
It has negative effect on the others.
Switching TCP middleware
The function of middleware • It observes the machine’s CWND.
• When it finds TCP working, it broadcasts the communicating condition.
• When it accepts other’s information, it selects suitable TCP for the environment.
• The TCP has a proc interface to switch.
• The middleware has a system call to rewrite the proc interface.
The Switching Algorithm • it switches TCP from original to cubic when the middleware notices the other
communication.
• it switches TCP from cubic to original when the middleware notices no other
communication.
Middleware
Experiment
The result of Experiment
Conclusion
• Android device 1 transmits 16 M byte of packets.
• Android device 2, 3 began to transmit 4 M byte of packets to interrupt.
• The middleware of each device share the information of communication.
• It switches TCP while the other device is communicating.
The normal behavior of TCP The behavior of switching TCP
Future works
My graduate thesis
Background