Transcript IBBT Poster

Implementation details
Access network controlled fast
handoff for streaming multimedia
in WLAN
•Mechanism:
•BS = AP + extra functionality
•Extra WLAN NIC (passive)
InterBS
Protocol
Wired
•An algorithm that is scheduled
several times per second:
•For each record:
•If received on the passive
interface:
Inter BS Protocol
•we send a message report to
the BS where the terminal is
connected to
•If received on the active
interface:
Terminal Info Protocol
•if a stronger average RSSI is
seen on a neighbor BS we will
Demo topology
hardware message
selectionto
send aand
terminalHop
the terminal
Hardware:
• BS: PC Engines WRAP
STA
info
Terminal
DB
AP
Filter
Beacons
per
Terminal
WLAN1
WLAN2
233 MHz AMD Geode SC1100 CPU - 2 LAN - 2 miniPCI
128 MB DRAM – 128MB compact flash
• Crew Terminal: HP Compac tc1100
P
BS X
A
Terminal
Content
Switch
P
A
A
BS Z
BS Y
P
Evaluation
• Sending 20Mb/s UDP with iPerf from
server to terminal
Attenuation
• Simulate motion → handoff every 15
seconds
• Average of 15 lost packets per handoff
• Lost packets ranged from 10 to 50
packets
SB
Content
ATT
4:1 2:1
• 30 of the 37 handoffs
→
less
14
lost
A
BS
1
Terminal
X
packets
in SB
2
P
• Results in < 10ms disconnection
time
BS A 3
Y
Switch
P
4
BS A
Z
5
P
6
ATT 1-2
ATT 3-4
ATT 5-6
Time
Bart Jooris, Abram Schoutteet and Ingrid Moerman •
[email protected] • Frederik Vermeulen •
[email protected]
Abstract - The focus of the
research presented in this
paper was to develop a novel
way to support voice over IP
(VoIP) and streaming video
applications
on
mobile
devices over a 802.11 access
network. Fast handoff in a
wireless local area network
(WLAN) environment has been
the research topic of many
previous
studies,
the
majority of which described
ways to optimize the three
main 802.11 handoff phases scanning, authentication, and
reassociation. In this paper
however we propose a fast
handoff scheme that skips all
mentioned
phases.
Instead,
the handoff is controlled and
prepared
by
the
access
network and is triggered by
sending a hop request message
to the mobile station (STA).
At the STA the three phases
are
reduced
to
a
single
frequency change phase. The
proposed solution extends the
standard 802.11 scheme; if
the
extension
is
not
available
at
the
access
network
or
the
STA,
the
devices will fall back on the
standard handoff
procedure.
Because the access network
Conclusions
fully controls the handoff
process
and actively
invokes
•The
presented
solution
for
the frequency
on the
the
horizontal change
handoff
is
STA,
we with
can the
guarantee
compatible
standardsa
minimal
802.3
and duration
802.11. of the time
the STA stays disconnected.
•The handoff implementation is
Index: Terms - Fast handoff,
fast
VoIP,
WLAN,
Broadband
•interruption
of
Communications
connection is guaranteed
below 50 ms
•we can support QoS for
multimedia
applications
(VoIP, video, ...) during
handoff