Cellular
Digital Packet Data (CDPD) is an overlay to the existing
D-AMPS cellular network, which enables
users to transmit packets of data over the cellular network using a
portable computing device and a CDPD modem.
- CDPD is an extension of existing data
networks
- The CDPD network supports multiple,
connectionless sessions
- CDPD airlink transmissions have a
19,200 bps raw data rate
- CDPD utilitzes the Internet Protocol
(IP) and OSI Connectionless Network Protocol (CLNP) for data
applications
CDPD
Network Entities:
Mobile-End System:
the M-ES can be any mobile computing device which has a CDPD modem
built-in or attached. The M-ES transmits data over the airlink to the
Mobile Data Base Station (MDBS) located in the cell site.
Mobile Data Base Station (MDBS):
Located at the cell site, the MDBS relays packets of data to the MD-IS
(Mobile Data Intermediate System) located at the MTSO (Mobile Telephone
Switching Office). The MDBS is primarily responsible for radio frequency
management, such as making sure the M-ES does not transmit on a frequency
that is currently being used by cellular voice, channel hopping, and
aiding the M-ES to transfer from one cell to another by assisting in the
location of a new channel.
Mobile Data Intermediate System
(MD-IS): The MD-IS keeps track of
an M-ES's location and routes data packets to and from the CDPD Network
and the M-ES appropriately. In addition, the MD-IS is responsible for
validating an M-ES on the network, and exchanging the encryption keys with
the M-ES that allows for secure transmission of data over the airlink.
Intermediate System (IS): The IS
routes the data through the IP and CLNP network. The Intermediate System
is a standard IP router with the primary responsibility of relaying data
packets.
Fixed-End System (F-ES): The F-ES
is the final destination of the message sent from an M-ES. The Fixed-End
System receives the data and processes it appropriately. The F-ES can be
one of many stationary computing devices, such as a host computer, a UNIX
workstation, an on-line information service, or another Mobile-End System.
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Chinese mobile phone market nearly doubled in 2000 to 85.3m users |
| BEIJING, 23 2
2001
The number of mobile phone users in China nearly doubled to 85.3 million last year, helped by the popularity of services such as short messaging, according to Business Weekly, citing a report from the Ministry of Information Industry.
The number of users was up 97 pct from 43.3 million users in 1999, it said.
Many Chinese, especially in the cities, decided to become cell phone users because of new services such as short messaging.
More value-added mobile services are expected in the coming months and many market analysts expect the growth momentum in the industry to be maintained, the paper said.
In another sign of the explosive growth of China's cell phone market, mobile telecommunications accounted for 42 pct of last year's total telecoms revenue of 307.4 billion yuan.
China's fixed-line telecoms market saw more modest growth of 35 million users last year, the paper reported, adding that this, given previously published statistics, suggests China's fixed-line market grew by 32 pct to 145 million users.
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