Considerations on the
Mobile Internet Architecture for High-Speed Wireless Networks
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INET 2001 Poster Session |
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June 5th – 8th ,
2001 |
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NTT DoCoMo |
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Authors Information
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Norihiro Ishikawa |
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(NTT DoCoMo Inc., Multimedia Labs.) |
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Email: ishikawa@mml.yrp.nttdocomo.co.jp |
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Hideharu Suzuki |
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(NTT DoCoMo Inc., Multimedia Labs.) |
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Email: hideharu@mml.yrp.nttdocomo.co.jp |
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Hidetoshi Ueno |
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(NTT DoCoMo Inc., Multimedia Labs.) |
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Email: uenohi@nttdocomo.co.jp |
Background
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Internet access from wireless
environment (mobile phone, PDA) is being increasing. |
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WAP Forum has developed WAP1.x protocol
that is optimized for wireless networks that have the characteristics such as
high latency and/or high error rate. |
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Functions and the performance of the
WAP protocol have not fully evaluated. |
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We have measured the performance of the
WAP protocol and compared it with that of the Internet protocol. |
What is WAP?
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WAP is developed by the WAP Forum
(established in 1997). |
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WAP is a protocol that is optimized for
wireless environment (mobile phone, PDA etc.) |
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Consists of WAP client, WAP getaway and
Origin server. |
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Optimized for wireless network
characteristics and provides special functions. |
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Telephony application, push
functionality, suspend & resume |
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WML(Wireless Markup Language) and
binary encoding |
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Many kinds of bearer support (GSM,
CDMA, PDC, SMS…). |
WAP Architecture
WAP Protocol stack
overview
WAP1.1 test-bed system
overview
Evaluation on WAP
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We evaluated the following items on the
WAP test-bed system. |
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Functionality evaluation |
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WAP Push |
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WAP push is one of the unique functions
in WAP. Investigating feasibility of WAP push is very important. |
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We developed an e-mail application
prototype by using the WAP push function. |
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Performance evaluation |
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Response time |
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Since response time is one of the key
factor of serviceability, we compared the response time of WAP1.1 and
HTTP/TCP. |
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WML binary encoding compression rate
and processing time |
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WML binary encoding is one of the
unique functions in WAP. |
Push functionality
evaluation(1/2)
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What is WAP push? |
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The WAP Push framework introduces a
means to transmit information to a WAP client. |
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WSP defines push methods (confirmed and
unconfirmed push) in addition to the methods defined by HTTP. |
Push functionality
evaluation (2/2)
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We developed an e-mail application
prototype by using the WAP push function. |
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Protocol conversion (SMTP to WSP) is
executed at the WAP gateway, and e-mail messages are pushed to the client
immediately. |
Considerations on Push
functionality
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An immediate push of a message (e.g.
e-mail, instant message) is desirable, from the mobile user’s point of view. |
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We concluded that the WAP push
functionality fulfils the above requirement. |
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WAP push is very feasible and usable in
the wireless environment. |
WAP performance
evaluation 1 (Response time)
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Evaluated the response time (from
request method to reply method) of WAP1.1 and the Internet protocol
(HTTP/TCP) over W-CDMA environment. |
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W-CDMA emulator emulates W-CDMA
environment, which can set up bearer speed, bearer error rate, latency and so
on. |
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Bearer speed |
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Uplink: 64kbps (fixed) |
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Downlink: 384kpbs, 64kbps |
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Bearer error rate:10% |
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Contents size |
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500, 10K, 100Kbytes |
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Protocol parameters |
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WTP maximum group size: 9600bytes |
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TCP receive buffer size: 9600bytes |
Response time comparison
Considerations on
response time
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WAP1.x would take an advantage if
content size were small, HTTP/TCP would take an advantage if content size
were large. |
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500byte(64kbps): WTP1.x is better than
HTTP/TCP. |
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100Kbyte(64kbps): HTTP/TCP is better
than WAP1.x. |
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Reason |
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Because TCP slow start algorithm
prevents making full use of network resources in the slow start phase, WTP is
better than TCP in case of small contents. |
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WTP responder can send the number of
packets based on the window size, but the WTP responder has to wait until the
subsequent acknowledgement is received. That waiting time results in the
increase of total response time. |
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TCP performance is better when
transmitting large contents because dynamic flow control mechanism works well
provided that the large size of buffer is prepared in the client. |
WTP and TCP communication
sequence comparison
WAP performance
evaluation 2 (WML binary encoding)
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WAP defines binary encoding of WML. |
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A WML content is encoded into binary
format at the WAP gateway. |
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We evaluated WML binary encoding
compression rate as well as processing time compared with gzip. |
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Content size: 500, 1000, 1400, 20K,
100K, 360K |
Binary encoding example
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<wml> |
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<card id="abc" ordered="true"> |
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<p> |
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<do type="accept"> |
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<go href="http://xyz.org/s"/> |
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</do> |
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X: $(X)<br/> |
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Y: $(Y)<br/> |
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Enter name: <input type="text" name="N"/> |
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</p> |
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</card> |
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</wml> |
WML binary encoding
comparison
Consideration on WML
binary encoding
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If content size were small, WML binary
encoding would be effective. On the other hand, gzip encoding would be
effective if content size were large. |
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WML encoding processing overhead would
increase considerably if content size were large. (In case of 360K, then
1730ms.) |
Discussion
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WAP1.x would take an advantage if
content size were small, HTTP/TCP would take an advantage if content size
were large. |
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Since 3G network handles larger
contents than 1G/2G, HTTP/TCP is more suitable than WAP1.x in the 3G
multimedia environment. |
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We propose the mobile Internet
architecture that is suitable for high-speed wireless networks such as |
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W-CDMA. |
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Consideration on proposed
architecture
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Seamless Internet access. |
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Provide End-to-End security by using
TLS tunneling. |
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HTTP/TCP would take an advantage if
content size were large. |
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Markup Language |
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Experience with the deployment of
i-mode. |
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Since i-mode adopts subset of HTML and
contents developers are familiar with it, there are many i-mode contents in
the Internet. |
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XHTML is expected to be the next
generation markup language. And XHTML Basic is expected to be a core language
for clients such as mobile phones that do not fully support of XHTML
features. |
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Push functionality |
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WAP push is very feasible and usable in
the wireless environment. |
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Provide push functionality over TCP by
using HTTP POST (implementing HTTP compact server on the phone, and HTTP
client on the WAP Gateway). |
Proposed Mobile Internet
Architecture for 3G network
Conclusion
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We developed WAP1.1 test-bed system. |
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Performance evaluation has shown that
WAP1.1 is suitable for application of small content size. |
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In 3G network, bearer speed is very
fast (384kbps-2Mbps) and contents are becoming large, so that Internet
standard protocols(HTTP/TCP) is applicable to the wireless environment with
some TCP modifications. |
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We proposed Mobile Internet
Architecture for high-speed wireless networks such as 3G. |