Data services in a TDMA digital portable radio system

Two kinds of data service are proposed: (1) a nonprotected data mode is provided for terminals which use an intelligent data link layer protocol and higher level protocols, where the radio link serves as a digital pipe similar to the physical layer in the OSI model; and (2) a protected data mode is provided for terminals which use simple start/stop flow control, where a radio link automatic repeat request (ARQ) protocol is introduced to recover from errors caused by the radio channel. The time slot format for the radio link ARQ protocol is described, and it is shown that a single time slot assignment can support a user transmission rate up to 5.5 kb/s in a protected data service mode. For user transmission rates higher than 5.5 kb/s (protected mode) or 8 kb/s (nonprotected mode), multiple time slots must be assigned to the user. The throughput of the Go-Back-N protocol when slow Rayleigh fading is encountered in both transmission directions and when two-branch selection diversity is used is obtained via computer simulation.<
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