File Transfers Over the GSM Network

        Field experiments with vendor handsets, data cards, and several common file transfer protocols have been performed to assess the quality of GSM data services of the type data circuit duplex asynchronous. File transfer times over many GSM-plus-PSTN links were measured and statistical performance figures for throughput, transmission efficiency, and network delay obtained. Suprisingly, best results were achieved with the transparent GSM 9.6 kbit/s data service and end-to-end retransmission. Although simple stop-and-wait protocols (XMODEM, YMODEM) did not perform well because of the large link delays, good throughput performance was obtained with sliding-window or other sophisticated retransmission schemes (KERMIT, ZMODEM). Even on very noisy links, throughput at 9.6 kbit/s was acceptable without need for stepping down to 4.8 kbit/s or 2.4 kbit/s. Use of the non-transparent GSM data service, which protects the air link with the GSM built-in radio-link protocol (RLP), yielded no additional performance gains.

By: Dietrich Maiwald and Chahram Zolfaghari

Published in: RZ2883 in 1996


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