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
LIMITED DISTRIBUTION NOTICE:
This Research Report is available. This report has been submitted for publication outside of IBM and will probably be copyrighted if accepted for publication. It has been issued as a Research Report for early dissemination of its contents. In view of the transfer of copyright to the outside publisher, its distribution outside of IBM prior to publication should be limited to peer communications and specific requests. After outside publication, requests should be filled only by reprints or legally obtained copies of the article (e.g., payment of royalties). I have read and understand this notice and am a member of the scientific community outside or inside of IBM seeking a single copy only.
Questions about this service can be mailed to reports@us.ibm.com .