For private satellite communications (satcom) networks, customized LTE has been an option, and 5G is becoming attractive with 3GPP standardization. LTE and 5G offer benefits such as high spectral efficiency, broadband capabilities with high data throughput, all-IP networks and economies of scale. Satcom networks using 5G will begin to be standardized starting with 3GPP Release 17.
With satcom systems, specialized knowledge of the environmental constraints is required to develop reliable systems. The networks need algorithm and protocol adaptations for a range of issues, creating new requirements compared to conventional LTE and 5G terrestrial networks. These include higher latency and interference or multiple parallel channels, particularly where satellites are sharing limited resources. Developing a satcom system using LTE or 5G requires a platform that can simulate and test the real world in a lab.
FLEXIBLE eNodeB
The LTE Reference eNodeB from CommAgility is a pre-integrated, 3GPP-compliant hardware and software system that serves as a key part of such a development system (see Figure 1). The LTE Reference eNodeB provides wireless baseband processing and a 2 x 2 MIMO air interface for radio test systems, small cells and user equipment (UE). The system is based on CommAgility’s CA-K2L-RF2 processing board, a low-cost, high performance ARM and DSP processing card with two wideband RF transceiver channels. It also includes CommAgility’s PHY and stack software, with example configurations for UE connectivity, and a 4G/5G management tool.
Figure 1 A satcom development system using CommAgility’s LTE Reference eNodeB.
The LTE Reference eNodeB provides a flexible and configurable platform that can be tailored to the needs of a private satcom network, saving development time and reducing risk. It generates the data to be transmitted over a simulated satellite network and handles standard, specialized or advanced LTE and 5G systems beyond Release 15 (see Figure 2). The system gives engineers access to internal eNodeB parameters to change the configuration. For specialized applications, CommAgility can provide source code and test vectors with test cases, customization services and fully integrated applications. The LTE Reference eNodeB handles real world satellite challenges, such as the complications of latency and Doppler shift, by manipulating the PHY source code and providing access to upper protocol layers.
LTE REFERENCE UE
CommAgility also offers an LTE Reference UE. This is a similar system with both hardware and software that can be integrated in a test system for eNodeB and network testing. The LTE Reference UE is based on CommAgility’s CA-D8A4-RF4, a baseband processing and RF card for eNodeB and UE. The card includes a Texas Instruments TCI6638K2K SoC and a Xilinx Kintex-7 FPGA with four flexible wideband RF channels. The RF channels are tunable in pairs over a wide frequency range to cover the LTE and unlicensed frequency bands, with RF bandwidth to 100 MHz to support carrier aggregation and 5G channels. The reference platform is also provided with PHY and stack software and example configurations for UE connectivity.
SIMPLIFYING COMPLEXITY
While platforms such as the LTE Reference eNodeB and UE provide an excellent start to a simulation platform, developing LTE systems can seem overwhelmingly complex, with hundreds of configuration parameters to manage and monitor. As the characteristics of the signal path change, developers need to measure performance metrics and assess the transmission quality users would perceive.
To address this issue, the CommAgility 4G/5G Management Tool enables objective and subjective evaluations of the client user experience. The tool provides a “friendly” and cost-effective graphical interface for monitoring the configuration parameters and data throughput, such as CPU statistics, uplink N+1 histograms, uplink N+1 per PRB, data plane statistics, data plane BLER and control plane. Compatible with CommAgility’s 4G/5G protocol stack, LTE Reference eNodeB and Reference UE software, the 4G/5G Management Tool saves effort, time and cost for managing and manipulating hundreds of configuration parameters. The parameters are validated to ensure safe operation and eliminate errors, enabling developers to reduce time to market while maintaining quality.
Together, these products reduce the development complexity and risk for satcom applications, providing the tools to customize LTE and 5G standards to meet the unique needs of satcom links, such as latency and interference.
SATELLITE 2020 DEMO
At the recent SATELLITE 2020 conference in Washington, D.C., Wireless Telecom Group (WTG) demonstrated 4G/5G communications for satcom networks using the LTE Reference eNodeB and Management Tool with other WTG products. Featuring signal generation, transport, impairment, monitoring and measurement, the demonstration showed how to overcome the challenges adapting cellular network technology over satellites. Using products from all five WTG companies - CommAgility, Boonton, Holzworth, Microlab and Noisecom - the simulated satcom network demonstrated the transmission and analysis of data over a link (see Figure 2). The effects of latency inherent with GEO satellites, Doppler shifts with LEO satellites, multiple satellite system hops, signal jamming, carrier-to-noise impairments, satellite signal combining and distribution were modeled, controlled and modified by the system, which also measured RF power, signal analysis and link quality.
Figure 2 Satcom test and evaluation system comprising WTG products.
Suitable for a wide range of wireless applications, the LTE Reference eNodeB and UE from CommAgility provide integrated hardware/software solutions, while the 4G/5G Management Tool streamlines the management of configuration parameters. CommAgility’s products, combined with WTG’s other solutions, give customers access to the combined expertise and knowledge of the five group companies, enabling fast development and deployment of private and secure satcom networks.
CommAgility
Loughborough, U.K.
www.commagility.com