CDPD: Cellular Digital Packet Data

What Is CDPD A service? A technology? A network? A standard?

Introduction In 1993, the first version of standard of CDPD came into view. In 1994, in America, the first CDPD experimental network run. CDPD offer one of the most advanced means of wireless data transmission technology. CDPD transmits digital packet data at 19.2 Kbps. CDPD system allow user to transmit data with a higher degree of accuracy, strong security, and few service interruption

CDPD Definition CDPD is a technique for quick transfer of data. It transmitts data at 19.2 kbps. It transmitt the packet over the cellular network in a reliable manner. In 1993, the first version of standard of CDPD came into view. In 1994, in America, the first CDPD experimental network run.

Key CDPD Characteristics 1.Availability: Identifies whether CDPD services can be acquired from a carrier in a given region 2.Coverage: Identifies whether CDPD transmission can reach users in a given region. 3.Reliability: Identifies whether user can access and use CDPD services during congestion or network disruption 4.Transmission Speed: Describe the end to end data speed, including call setup time & transmission speed

Key CDPD Characteristics 5. Privacy and Security: Describe the level of inherent privacy and security of the service and the capability to add security measure 6. Cost: Characterizes the cost typical of CDPD service.

Features 1.Same Coverage as cellular system 2.Schedule data packets to unused voice channel Kbps raw data transfer rate. 4.Full duplex transreciever mw transmit power 6.Integrated TCP/IP protocol stack 7.Compact size 8.Strong aluminum case 9.LED’s show status of CDPD operation

Working Of CDPD It uses Channel Hopping Technique. Initiates data transmission Location Of available channel to establish data link. Mobile data unit transmit data packets. CDPD technology transmits chunks or packets of data Equipment : 1) CDPD Modem 2) User terminal

UserEquipment User Equipment 1.CDPD Modem: It Includes wireless antenna and modem that provides compatibility with network. It can be internal or external. 2.User Terminal: Any device that supports IP-based data communication can use CDPD. Examples are as notebook or laptop Personal Computers (PCs), handheld computers or PCs.

Interfaces A Interface : Air interface I Interface : Intermediate system interface E Interface : External interface

Components 1. Mobile End System ( M-ES) Mobile computing device which has a cdpd modem built-in or attached It support mac functionality It transmit data over the airlink to MDBS It should provide transparent interface to the user application Example is CDPD modem

Components 2. Mobile data base station (MDBS) It located at the cell site. It is responsible for R.F management It provide hop to hop control over the air interface It controls the hop & RF segment between the M-ES and the cdpd network Cellular geographic area control by MDBS

Components 3. Mobile Data Intermediate System(MDIS) 3. Mobile Data Intermediate System(MDIS) MDIS routs data packet to and from the CDPD N.W & the M-ES appropriately It validates M-ES using encryption keys for secure transmission of data It is responsible for IP routing An MDIS may serve single or multiple CGSA cells It can provides mobile home & serving functions

Components 4. INTERMEDIATE SYSTEM (IS) 4. INTERMEDIATE SYSTEM (IS) It is the standard IP router It routes the data through IP & CLNP, N.W The IS components are the backbone of CDPD mesh

Components 5. FIXED END SYSTEM (F- ES) 5. FIXED END SYSTEM (F- ES) F-ES is the final destination of message sent from M-ES F-ES received the data & process it appropriately The F-Es can be one of many stationary computing devices such as host computer, UNIX workstation

CDPD - Layering Physical MAC MDLP SNDCP IP/CLNP Physical Data link Network TransportApplication Network layer CDPD Layer Network layer CDPD Layer Connectionless Network Protocol Subnetwork Dependant Convergence Protocol Mobile Data Link Protocol Media Access Control Physical

Mobile Data Link Protocol It provides logical link control services between Mobile End Systems and Mobile Data Intermediate Systems. The purpose of MDLP is to transmit information between network layer entities across the CDPD Air link interface. High-level data link control (HDLC) Temporary equipment identifier (TEI) Identifies destination mobile - virtual address.

Subnetwork Dependent Convergence Protocol  Encryption/decryption  User data confidentiality  SNDCP provides a number of services to the network layer  Compression/elimination of redundant protocol control information

Mobile Network Registration Protocol  Exchange of routing and registration information between the M-ES and a serving MD-IS.  Delivery of authentication information about an M-ES.  Registration and Authentication of multicast NEI.

Radio Resource Management  It prevents interference of radio channel and other wireless communication characteristic.  RRM concerns multi-user and multi-cell network capacity issues, rather than point-to-point channel capacity.  The objective of radio resource management is to maximize the system spectral efficiency in bit/s/Hz/base station site or Erlang/MHz/site.

Application of CDPD Credit card verification ATM network Transportation: Ambulance, dispatch system. Public security: Policemen can access the latest database in real time to. E.g. Check suspected person, Verify identity. Check the car current status. Remote measurement: Remote control. Commerce. Wireless ATM. Wireless Credits Card Authentication. Mobile Payment.

Application of CDPD Implementing easily. High speed. CDPD modem set up time is much faster than wire dial up modem. Even CDPD is 19.2kbps, wire dial up modem is 33.6kbps. Reliable and Safety with strong encryption algorithm. Personal use which covers the main part of the CDPD usage.

Wireless ATM Via CDPD More and more popular in China. Very convenient. CDPD provides reliable, fast and safe access. Maintenance is not very high.

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