A Modular Family of High Data Rate SDR Transceivers

IQ wireless GmbH developed a family of modular SDR transceivers to serve a wide range of different mission scenarios. Transceivers of this family are formed by two printed circuit boards accommodated in a compact housing. The SDR platform handles data interface and coding, while the analogue frontend implements frequency conversion and amplification. To increase the potential for customization, the architecture provides two independent channels for both upand downlink. The first implementation of the new transceiver design is the X band transmitter XLink that was developed in cooperation with Technische Universität Berlin. Here, the two downlink channels are both configured for X band transmission. In a first development step, broadband data rates up to 25 Mbps are achieved and CCSDS compliance facilitates the use of existing ground infrastructure. Alternative configurations use both channels for redundancy and MIMO to implement highly reliable and efficient proprietary transmission modes. The implementation of increased data rates in the range of 150 Mbps is currently investigated. The two uplink channels of XLink are configured to support X and S band, respectively. This paper presents the transceiver family’s architecture and details the XLink configuration including results from the ground qualification campaign and performance testing. INTRODUCTION During recent years, the performance capabilities of small satellites and especially CubeSats improved substantially. Here, the ever more sophisticated applications such as Earth observation with highresolution optical payloads or radars call for everincreasing data downlink capabilities while requiring keeping the utilized radio transceivers at a limited size and weight. In this context, peak data rates of more than 200 Mbit/s could already be demonstrated on a 3U CubeSat in X band [1]. Flexibility is also becoming a significant aspect in satellite communication, as applications such as IoT networks require transceivers that allow communication between multiple nodes and in some cases the ability to be reconfigured in flight. Another application with increasing commercial interest is constellations of large numbers of communication satellites, which drive the need for data throughput and flexible communication solutions such as inter-satellite links. Here, software-defined-radio (SDR) based transceivers are particularly relevant, as they can be adapted to different use-cases and may even be reconfigured after launch by means of software updates [2,3]. Furthermore, SDR-based transceivers allow to implement capabilities that were traditionally performed by complex hardware modems such as CCSDS-compliant protocols or two-way ranging [4]. In this context IQ wireless GmbH developed a family of flexible SDR transceivers that can be adjusted to a wide range of application scenarios. The X band transceiver XLink is the first implementation within this family [5]. This paper gives an overview over the architecture of the transceiver family and details design and ground qualification of the XLink transceiver. TRANSCEIVER FAMILY ARCHITECTURE It is a common approach to use commercial-off-theshelf (COTS) components stemming from industries such as consumer electronics and automotive to develop small satellite equipment offering high performance at low mass and volume. In the field of radio frequency (RF) advanced transmission schemes furthermore enable efficient transceiver designs offering high datarates and reliable transmission. Here, especially the use of forward error correction (FEC) based on convolutional codes, TURBO codes, or low-density parity check codes (LDPC), as well as the implementation of higher order modulation schemes such as APSK are commonly used for small satellite transceivers. However, other techniques widely used in terrestrial communication systems may offer additional potential to increase the performance of such devices:  Adaptive modulation and coding procedures (AMC)  Multiple input multiple output (MIMO) schemes The presented family of high data-rate SDR transceivers enables the application of such approaches