Towards the Terabit/s satellite – interference issues in the user link

Abstract

Present high-capacity geostationary satellites provide throughput in the range of 70 Gb/s (Ka-Sat) up to 140 Gb/s EchoStar 17). In order to keep up with the quickly increasing bit rate requirements of new services and applications, future communication satellites must increase their capacity by an order of magnitude, thus reaching the terabit/s throughput range. The challenge of achieving a terabit/s satellite system requires investigation of a multitude of issues, limitations and problems.This paper discusses the main interference effects occurring in the user uplinks and downlinks of a multi-beam satellite: co-channel interference, adjacent-channel interference and cross-polarisation interference. Different cluster sizes for the beam pattern and use of dual polarisations are considered, and an optimum cluster scheme with regard to throughput is discussed in more detail. Moreover, the influence of beam spacing, interference cancellation for the user uplink as well as rain fading for the uplink and downlink are discussed. For the satellite spot beam antenna, a typical tapered antenna characteristic with side lobes is considered. The investigation is based on Monte Carlo simulation of user positions within the beam pattern, resulting in CDFs of signal-to-noise-plus-interference power ratio and capacity. Besides Shannon capacity, the achievable throughput of Digital Video Broadcasting -Return Channel over Satellite, 2nd Generation (DVB-RCS2), Digital Video Broadcasting over Satellite, 2nd Generation (DVB-S2) and Digital Video Broadcasting over Satellite, 2nd Generation, Extension (DVB-S2X) is evaluated. Considering 200 beams and 1 GHz of bandwidth, it is shown that with efficient uplink and downlink schemes, a total throughput of 1 Tb/s can be approached.

Performance Assessment of Coded-Beam High Throughput Satellites

“…In [17], various interference effects (CCI, ACI and XPI) and thermal noise have been discussed, and numerical results for SNIR, bandwidth efficiency and throughput have been presented over 200 beams with 1 GHz Bandwidth and parameters included in the DVB-S2X, applying these parameters to the proposed scheme using G p = 8, ρ = 0.05, typical value of SNR = 18 dB results user information rate per beam equals to 249.999 Mbps and system throughput of 1.00655 Tbps which is higher than the maximum value achieved in [17] (the 420 Gbps for the use of three frequencies and use of dual polarizations in each beam (3FDP) with interference cancellation of about 70% of interference ) by 140% above, each user Occupies triple the bandwidth used in the 3FDP scheme without wasting polarization resource.…”

Ka‐band HTS channel uplink SNIR probability model

“…The CCIs and SNIR of the Ka‐band HTSs have been studied recently as part of the efforts to achieve HTS system optimal resource allocation and to estimate throughput via simulations. The distributions of the CCIs and SNIRs obtained in those studies are spatial distributions where each CCI is a fixed value which best describes the open space user terminal (UT) scenario . In , the total CCI pdf as a distribution function of CCI transmitter locations in the coverage area is found to approximate a non‐central chi‐squared ( χ 2 ) distribution in the simulations.…”

“…The challenge in obtaining the sum pdf of a large number of CCI RVs shown in Equation and line 2 of Equation is overcome by exploring the particular characteristics of the Ka‐band HTS systems. For uplink of different slant paths, the CCI RVs are independent from each other and from the desired signal RV through either the rain or the clear‐sky LOS slant paths because they are geometrically well separated at regular reuse 3 under consideration, and with a very small probability the rain in one CCB spans to another CCB . They each assume a channel power RV y with a distribution either χ 2 in (6) or composite Lognormal in (10).…”

“…By reusing frequency and polarivzation (color reuse) among the spot beams, high throughput satellite (HTS) systems are created, which have reached capacity to 100 s of gigabytes . However, crossing the 10 GHz frequency limit into Ka‐band gives rise to significant signal fading induced by the tropospheric precipitation in the slant paths , and color reuse produces co‐color interference (CCI) to the desired signal . Both impairments vary randomly, degrade channel performances, and erode ideally achievable capacity.…”

“…A channel capacity or link throughput by bit rate is achievable for a given channel SNIR and the available system resources . The HTS channel SNIR distributions are used in link throughput estimation at the system planning stage and optimal resource allocation via adaptive coding and modulation in the physical layer during system operation . The channel SNIR cumulative distribution function (cdf) directly leads to link outage probability.…”