Impact of Status Retry Timer Values on MFTP Performance over BGAN Satellite Multicast

Abstract

MFTP is a multicast transport protocol optimized for reliable file transfers. MFTP is rate based, which means that the transmission rate can be configured. By limiting the transmission rate one can reserve bandwidth for other protocols. MFTP uses a NACK based error correction scheme where the server is almost constantly sending data and very seldom has to wait for acknowledgements from the clients. MFTP sends a file in passes. The first pass represents the complete file while subsequent passes represent data identified as not received by clients in NACK messages. This makes MFTP specially suited for transmissions over links with long delays, for example satellite links. This paper analyses MFTP multicast performance over Inmarsat BGAN multicast satellite system. The full interaction between the MFTP server and MFTP clients deployed over the Inmarsat BGAN down link multicast delivery mechanism along with BGAN uplink access mechanism is considered. The performance evaluation is based on a BGAN multicast system level simulator. The analyses aims to evaluate and optimize MFTP performance in Inmarsat BGAN system in terms of file transfer delay and system throughput as a function of available capacity, client population size, data product size, channel error characteristics, and MFTP protocol settings.

Ambiguity function of Inmarsat BGAN signal for radar application

“…This spectrum is divided into several channels each with a nominal bandwidth of 200 kHz. In a single frequency channel, a bearer with format type F80T4.5X8B is transmitted [3]. The bearer has a frame length of 80 ms and occupies a bandwidth of 189 kHz.…”