A key component of the space solar power grid is the communication system that provides control and status between the space grid satellites and the ground stations. The communication system allows for sending of orbital correction commands, attitude correction commands, collecting satellite status, and running built in test.

Due to the critical role that the space solar power grid will play in the day-to-day life of millions of customers, a reliable communication link with the grid is critical to mission success. The design of the communications link will be 99.9% reliable with continuous coverage along the entire orbit. In this communication link design, the importance of reliability far exceeds the need for a high data rate.

Due to high reliability, low weather losses, and proven technology, we utilize a 4 GHz C band downlink with a 6.25 GHz uplink [1]. Each rectenna installation will have a communications antenna and there will be several other communications Earth-stations throughout the world to provide redundancy and increased jamming resistance.

We employ frequency hopping spread spectrum (FHSS) CDMA to allow for simultaneous access, low probability of intercept (LPI), and low probability of detection (LPD) [3], and increased jamming resistance. Transmissions are encrypted with the advanced encryption standard (AES) for communications security. Jamming resistance is achieved through site diversity and frequency hopping.

The communication system design employs a QPSK modulation type with a raised root cosine pulse shaping filter. We employ Reed-Solomon encoding. The link budget shows a sufficient amount of SNR with a large margin to ensure high reliability comms.