Characteristics of Satellite System with Wideband Spreading Signals overlaid on Conventional FDMA Signals within FSS Network

摘要

This paper presents characteristics of a satellite system with wideband spreading signals overlaid on conventional FDMA signals within an FSS network using Direct Sequence (DS) technology. This type of application could enable the transmission of additional information using wideband spreading signals within the same transponder. In particular, it could be suitable in the event of natural disasters and similar emergencies for warning and relief operations, because a receiver with a semi omni-directional antenna (e.g. 5dBi) does not require an antenna pointing to the satellite direction, which can be easily changed in such events. Moreover, interference from adjacent satellites is expected to be mitigated by its spreading gain, even if a low-gain antenna is used. We have evaluated the achievable data rate by link budget analysis, which shows that a data rate of several tens of kbit/s is obtainable with an antenna of 5 dBi. Although a relatively low data rate is achieved, due to the limited bandwidth and the C/I criteria, it is still considered to be sufficient to deliver low-rate emergency information.