N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 9 - Wireless Systems and Technologies                                                                                 Slide 11 of 80                                                                                                    ________________

    Cellular Digital Packet Data (CDPD)

                                    Developed by IBM and McCaw Cellular Communications

                                    Carrying Data over Analogue Cellular Radio Systems

                                    Data Packets transmitted during the Gap in Conversation

                                    Supports Encryption and Authentication

                                                                                                   ________________

A method developed to carry data over analog cellular radio systems. It uses channels not used for a voice call. Data to be transmitted is chunked into 138 bytes packets. The packets are transmitted in full-duplex at 19.2 K bps during the gap in conversation. This way the system's idle channels provide spare capacity.

CDPD is an open specification:     http://www.cdpd.org

Applications:    - United Parcel Service uses CDPD technology for parcel scanning, customer tracking of a
                         parcel and tracking delivery resources.
                       - Limousine and Taxi dispatches