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1 WLAN Introduction
WLAN
product was released in 90s, initially used in point to point and
point to multi-point data communication. The 802.11 standard released
in 1997, the 802.11b standard released in late 1999 and the foundation
of WI-FI organization promote the compatibility and standardization
of WLAN product. With the popularization of laptop computers, the
market for WLAN products has been developing more and more rapidly.
Office and individual clients begin to build LAN, used for sharing
data, transmitting file and wireless Internet, with WLAN technique
in hotels, departments, storages and so on.
WLAN
has attracted more and more attention. At present, products supporting
802.11b standard hold the main market share of WLAN and the technique
of which is the main topic of the paper. 802.11b products work on
the frequency ranging from 2.4G to 2.4835GHz, with DS spreading,
CCK (Complementary Code Keying) modulation and the peak data rate
of the air interface is 11Mbit/s, the information bit rate achieves
6Mbit/s. The frequency band is shared according to the CSMA/CA protocol.
Users
in WLAN are mobile. That they can roam among the APs (Access Points)
and achieve high data rate. For telecommunication operators, WLAN,
is an extension and supplement of wire network, can be deployed
for network coverage when the deployment of wire network is difficult
or urgent. An appropriate WLAN service is to be used in deploying
wireless network in large games or exhibition halls where the mobile
data service is needed.
2 Introduction of Beijing Telecom WLAN service in the 21st Universiade
In
the 21st Universiade, Beijing Telecom, as the only appointed sponsor
for data communication and wire communication, provided wide bandwidth
WLAN wireless Internet service. Beijing Telecom deployed wireless
network in International Conference Center where the News Center
locates, the Capital Workers' Gymnasium where the Ceremony was held,
the Universiade Village area and so on. Users can roam freely in
the wireless network. News reporters only need to plug a WLAN card
in laptop computer to link to the Internet through WLAN. Practical
applications are text and image transmission, high speed WEB browsing,
file downloading, video-on-demand and so on. Users in the News Center
can enjoy ceremonies being held in other gymnasiums and live sports
games.
The
WLAN network structure of the Universiade is as follows: each AP
is linked to the 100M port of 163 IP backbone network 6509 (double
ports back-up) through private line and Radius Server is used for
user identification. Users link to the Beijing Telecom interface
page through laptop or table PC with WLAN card, put in user name
and password, and log on the WLAN after indentity authorization.
Then the user can send Email or browse pages.
WLAN
service is welcomed in the Universiade and is called as "the
bright focus of the communication technique in the Universiade".
Many conventional and internet media gave special reports on it.
At the same time, the timely and considerate WLAN service helped
to emphasize the "technique Universiade" and was affirmed
by the Universiade Organizing Committee.
The
most convenience of the WLAN service felt by news reporters, the
main users, is that in the reporting rooms on the stand or in their
working rooms, they can directly send text manuscript and images
screened by digital camera to the newsroom through WLAN wide band
network. In the past, this is usually done when they come back to
hotel or the News Center to dial on the net. So the wireless wide
band network service greatly reduced the time during which the reporters
must wait for manuscript transmission. Thus the Beijing Telecom
wide band wireless network has made it true that reporters can interview
and edit on spot, and immediately transmit the manuscript to the
newsroom through 11Mbit/s wireless network air interface.
In
the survey on the WLAN service that carried out in the same time,
30% users think the cost of 50Yuan RMB per day is acceptable, 40%
users approve to pay by the length of application time and 21% tend
to pay by the data volume.
In
the Universiade, Beijing Telecom, incisively grasping the WLAN developing
opportunity and depending on the wide band IP backbone network and
wide area optic network, accomplished the project argumentation
and network deployment of WLAN service in only one month. It represents
the quick service response and deployment ability of main telecommunication
corporation and accumulates experience for future telecommunication
service in big games.
3 Examples of typical WLAN application situation
Compared
with conventional integrated routing Ethernet, WLAN has many advantages:
(1)
Only need to set Aps (Access Point). Easy to deploy. Save cost and
time for setting APs in integrated routing mode.
(2)
Without unorderly wire links on tables in office.
(3)
Realize mobile office together with portable laptop computers. Users
can link to the net in bedroom, living room and TV room. Satisfy
users' pursuing for individuality.
Typical
application environment
(1)
Office environment
In
office environment, for example, in an office of 20*50m2 and 30-40
people, usually 3 APs can meet the capacity and coverage requirement.
At present, the price of lower end AP product is less than 2000Yuan
RMB.
(2)
Home environment
One
AP can cover 100 m2 home area. For outside connection, ADSL can
be used to link to the Internet thus can realize the dream of avoiding
surfing on net through wires at home.
4 Views on the development of WLAN service and products
With
the WLAN service promotion by big domestic and overseas operators,
the price of AP device and wireless network card reduced greatly.
We hold the view that, in one to two years (late 2002 to 2003),
the number of domestic WLAN users will increase greatly and WLAN
will become the new hot spot in communication field; the WLAN terminal
equipments will include laptop computer, table PC, PDA and office
devices such as printers and so on; WLAN card will become the necessary
device for computer users; WLAN will be widely applied in high-grade
resident areas and hotels. According to data from Cahners In-stat
(shown in Figure 2), the global WLAN sales value in 2001 is 2.068
billion $, increased 54% compared with that in 2000 and is expected
to be 2.963 billion $ in 2002.
It
can't be predicted now if the WLAN will be the mainstream of wireless
data communication in the 2008 Beijing Olympics, but WLAN is sure
to hold a place for its relatively integrated and easy technical
system, wide industry basis and specially reserved frequency band.
The present situation reminds us of the early 90s in the previous
century when people were making choices on LAN technique among Ethernet,
TOKEN RING, FDDI and so on. The final choice is Ethernet that has
more practical application and is used as the common technique in
LAN.
According
to the application, the development of the WLAN products has the
following trends:
1.
Its price will be further reduced and it will be used as "wireless
hub". Application environment: inside small-sized corporation,
LAN linking and Internet surfing at home.
2.
Integrated with switching and routing techniques on the second and
third layer. For example: realize effective user data separation
together with the switching device that has the VLAN ability. Application
environment: extension for wire link; applied in hotel or local
area.
3.
Equipment manufacturers will have to strengthen device development
for further telecommunication application based on the existing
WLAN device, such as second separation, load sharing, automatic
frequency selection, mobile IP. They must try to provide integrated
solution for user authorization, billing, network management and
so on.
5 Conclusion
After
finished the service for the 21st Universiade, Beijing Telecom also
deployed WLAN in Beijing International Exhibition Center to provide
convenient and quick wireless Internet for corporations involved
in the exhibition. They will continue to deploy WLAN coverage in
airports, big meeting sites, office buildings and hotels.
WLAN
will soon become the bright spot of new telecommunication service
and welcomed by users. In the near future, it will "move from
the nobility to the common citizen" and become new fashion
for network users. It will also act as a powerful tool for telecommunication
operators to serve people and promote the informationization development
of our society.
Beijing
Communication Corporation, as the forerunner of domestic WLAN industry,
will more actively promote this service. It's sure that with the
common work of the whole industry, more and more people will be
able to enjoy the convenient and quick WLAN service in the near
future.
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Biography:
LI
Yan-song The author graduated from Department of Electronic Engineering
of Tsinghua University in 1998 with a master degree, and is currently
engaged in development of value-added services for BeijingCom.
WEN
Hui Currently a Senior Engineer with BeijingCom, the author graduated
from Changchun University of Posts and Telecoms in 1985. Before
being promoted to the post of Chief Manager of Wireless Project
in 1997 with Division of Information and Technology, the author
worked for the Satellite Earth Station of Beijing Wireless Communications
Bureau.
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