Joint IP Modem performance Using WGS

Abstract

The joint IP modem (JIPM) includes a forward (DVB-S2) and a return (DVB-RCS) link capability with a plethora of modulations and error correcting codes. In addition there is variable modulation and coding (VCM), adaptive modulation and coding (ACM) as well as uplink power control capability. The wideband global SATCOM (WGS) satellite has both Ka-band and X-band capability utilizing 39 active channels of up to 125 MHz bandwidth each. This paper addresses the JIPM hub/spoke topology at Ka-band and determines the constraints and requirements on the user VSAT terminals to support global broadcast service (GBS) traffic. Two GBS upgraded terminal capabilities will be considered: GBS receive-only using the JIPM DVB-S2 receive-only capability and two-way service using the JIPM with a GBS terminal capable of supporting two-way transmission on WGS. Achievable data rates using the upgraded GBS terminal will be presented. The forward link data rates are improved by the use of DVB-S2 over the current DVB-S waveform. The terminal capabilities at Ka-band are determined by a number of return link considerations: the throughput in the return direction, propagation conditions at the terminal, the actual WGS beam being used and number of 125 MHz channels being used in that beam, the sharing of the beam with other users, location of the terminal within the beam, the pointing/tracking error for the GBS terminal. This paper considers the next generation receive terminal (NGRT) as the targeted GBS terminal for upgrade for both 2-way operation and the JIPM addition.