Richard Gibbons

Link Analysis of Commercial and Wideband Gapfiller Satellite (WGS) Satellites Using DVB-S2 with Variable Coding and Modulation (VCM)

A link analysis was performed of the digital video broadcast-satellite (DVB-S) second generation waveform (DVB-S2) using a commercial (Ku band) and the wideband gapfiller satellite (WGS) satellite at X-band and Ka-band. The analysis is for the CENTCOM VSAT network (also known as the global war on terrorism [GWOT] network) that uses the EUTELSAT W6 satellite (21.5deg east) and supports both forward (DVB-S) and return traffic [DVB-return channel by satellite (RCS)] traffic in the same 72 MHz transponder. The forward traffic consists of nominal DVB-S broadcasts to receive-only terminals (1 m) as well as duplex 1.8 m and 2.4 m terminals. The return traffic consists of constant-rate, tactical, video feeds (from the 2.4m terminals) along with SIPRNET Internet protocol (IP) interactive traffic (from the 1.8 m terminals). The hub is located at Landstuhl, Germany. The paper considers 3 cases. First, the capacity of the Eutelsat W6 transponder is computed for the forward and return traffic sharing the same transponder. Next, the capacity is computed for DVB-S2 using constant coding and modulation (CCM) and variable coding and modulation (VCM) over the baseline GWOT network. Finally, the system capacity is computed using WGS (at 60deg east) again using DVB-S2 with CCM and VCM and DVB-RCS

Potential future applications for the Tracking and Data Relay Satellite II (TDRS II) system

Abstract During the conceptual design phases of the tracking and data relay satellite (TDRS) II system provision was made for a future service growth (FSG) payload with an undefined mission. The intent of the FSG was to provide a resource for TDRS II applications which would be available to meet a change in requirements for the operational TDRS II system. This paper summarizes the effect of the consideration of potential FSG applications imposed on the tracking and data relay satellite (TDRS) II system.The following applications were considered as FSG candidates: • • An optical 650 Mbps space-to-space link (SSL) coupled to an optical or RF downlink [1] • • An RF or optical crosslink to extend the baseline TDRS II system coverage —zone of exclusion (ZOE) closure [1] • • Relay for lunar communications either RF or optically • • Relay for Martian communications either RF or optically This paper summarizes work done in the 1990 time frame on the above stated applications. Since then, NASA has sponsored several studies (during phase B of the TDRS II development cycle) of the ZOE closure application of the FSG. The purpose of this paper is to report on the efforts previously considered for the FSG. A previous paper was presented at the 1991 Congress related to the second application above. This paper extends this effort to the four stated applications.

WGS Capacity using the DoD Joint IP Modem (DVB-S2, RCS)

The DoD joint internet protocol modem is based on the digital video broadcast (DVB) standard. In a star network topology the forward traffic is DVB-Satellite 2 (DVB-S2) and the return traffic is DVB-return channel by satellite (DVB-RCS). The joint modem adds an embedded TRANSEC capability and a mesh overlay allowing user terminals to communicate without passing through the hub. The analysis will take advantage of the variable coding and modulation (VCM) feature [as well as the constant coding and modulation (CCM) feature of DVB-S]. First, the DVB-S2 capacity will be determined for wideband gapfiller satellite (WGS) located at 175deg east using a set of reference links located in Korea using CCM and VCM in the forward direction. Then the capacity of WGS will be determined in the return direction using DVB-RCS. Finally, the mesh capacity will be determined using WGS with VSAT terminals (1m) in Korea for voice over internet protocol (VoIP) traffic

The Rucksack Portable Receive Suite performance over WGS using the DVB-S2 Mini IRD

The Rucksack Portable Receive Suite (RPRS) is a light weight (less than 20 lbs.) GBS RS using a Ka-band phased array (approximately 193 square inches). The RPRS is capable of operation with a Mini Integrated Receiver Decoder (MIRD). The MIRD uses a limited version of the DVB-S2 standard (QPSK only with symbol rates from 1Msps to 23Msps in 1Msps increments). The MIRD is receive-only with a single tuner and is certified for TRANSEC operation.

The RCS network return link performance using the JIPM over WGS1, 2, 3

The Wideband Global System is currently operational on WGS1 (175E), WGS2 (60E) and will shortly be operational on WGS3 (12W). The RCS Network is supported today on WGS2 using the Digital Video Broadcast by Satellite (DVB-S) in the forward direction and the DVB-Return Channel by Satellite (DVB-RCS) in the return direction (VSAT-to-Teleport/hub). There are plans to replace the current Modems with the Joint Internet Protocol Modem (JIPM). The remote JIPM Modem has two DVB-S2 receivers and has inherent two-way capability using DVB-RCS. A prime motivation to transition to the JIPM is that it has imbedded TRANSEC. In addition there are plans for two-way GBS operation using similar size terminals as in the RCS Network. Only the Constant Coding and Modulation (CCM) case will be considered in this paper. This paper will address the performance of RCS Network terminals using the JIPM over WGS1 (175E), WGS2 (60E) and WGS3 (12W) when used in the return direction at Ka-band. First, reference links will be defined using the RCS Network two-way antennas for operation over WGS at Ka-band. The reference links will be used to determine supportable propagation losses for several user rates of operational interest using WGS spot beams. This will be analyzed using the current Advantech Modem as well as the JIPM Modem. These point designs will be expanded globally by moving on a global grid and calculating the new grid availabilities as the propagation conditions and free space losses change. WGS and JIPM measurements will be used in the link analysis. The performance of the current (Advantech) and JIPM Modems will be compared.

Joint IP Modem performance Using WGS

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.

The NASA mobile satellite communications experiment opportunity

Emerging applications of commercial mobile satellite communications include satellite delivery of compact disc (CD) quality radio to car drivers who can select their favorite programming as they drive any distance; transmission of current air traffic data to aircraft; and handheld communication of data and images from any remote corner of the world. Experiments with the enabling technologies and tests and demonstrations of these concepts are being conducted before the first satellite is launched by utilizing an existing NASA spacecraft.

GBS over WGS Using DVB-S and DVB-S2 (#1546)

This paper determines the link performance of Global Broadcast Service (GBS) when it is transitioned to Wideband Global SATCOM (WGS) satellites. Current and future (smaller) GBS terminals as well as current Digital Video Broadcast-Satellite (DVB-S) and future (DVB-S2) Modems are considered. DVB-S2 provides a large increase in capability in terms of modulations and forward error correcting coding rates. In addition, DVB-S2 allows for different modulations and coding to different terminals using variable coding and modulation (different streams are coded with different, fixed parameters within the DVB-S2 physical layer frame). Further DVB-S2 allows adaptive coding and modulation whereby each frame is coded with its own set of parameters (which are dynamically modified according to reception conditions). The WGS performance will be based on a System Utilization Plan (SUP) including a frequency plan and beam configuration applied to the first WGS satellite placed in orbit at 175E. The WGS SUP includes a case where two uplink carriers in a single WGS 125 MHz channel are fanned-out to two Ka-band downlink beams where the downlink carriers share the same channel. Cases where the single GBS downlink carrier shares the 125 MHz channel with non-GBS traffic are also considered. A Theater Injection Point (TIP) uplink into a narrow beam with the downlink in a wide bean is also defined. Several propagation margins are considered to allow results to be applied to different receive terminal locations.

DVB link analysis using commercial and wideband Gapfiller satellites

A link analysis was performed of the two-way digital video broadcast (DVB) waveform using a commercial (Ku band) transponder as well as a wideband Gapfiller satellite (WGS) system covering the region of South West Asia (SWA), The forward traffic consists of nominal DVB-S broadcasts. The return traffic consists of constant rate video feeds along with SIPRNET IP interactive traffic. The hub is located at Landstuhl, Germany. The analysis indicates the expected capacities from commercial Ku-band transponder as well as from WGS using either DVB-S, RCS or DVB-S2, RCS

Extended definition TV over an analog FM satellite channel

The performance of several extended definition TV (EDTV) formats are compared in terms of signal-to-noise ratio (SNR) operation in an analog FM satellite channel. The formats considered are the National Television System Committee (NTSC), extended NTSC (ENTSC), multiplexed analog components (MAC), and extend MAC (EMAC). These formats are compared in terms of SNR above and below the FM threshold. Analytically derived curves which show the luminance and chrominance SNR as a function of horizontal resolution for the above-threshold operation are presented. The effect of group delay on the composite video formats is determined for an actual satellite channel. The below-threshold performances for NTSC and MAC are compared in the luminance channel. >