Integration of Wireless Sensor Network with CubeSat Satellite System for Enhanced Agricultural Monitoring

Direct-to-Satellite (DtS) uplinks by many low-power devices create a classic many-to-one contention problem during short visibility windows. This work proposes a hierarchical mesh→gateway→satellite architecture and a lightweight contention-mitigation protocol that combines randomized backoff with a Time Division Multiple Access (TDMA) style slotting. A simulation was developed that shows a gateway discovery model (effective slot budget B, per-window randomized access, deterministic polling once discovered) with an implementation of a Meshtastic-based ground-mesh model. Under standard assumptions (aligned slots, no doppler, benign adjacent-channel interference), the discovery model predicts fast convergence for small gateway populations: most gateway register within one to a few windows (mean ≈2.9 windows in the runs), bounded collisions, and stable acknowledgement→data-request→gateway-data handshakes. We validate end-to-end behavior with three experiments of increasing difficulty: a static lab setup with the whole system on a desk, a 5.09km urban roof link, and a high-altitude balloon (5.6km altitude, 12.43km slant range). Across these experiments or tests, performance degrades smoothly with Received Signal Strength Indication (RSSI) or Signal to Noise Ratio (SNR) (negative-SNR fraction 0%→15%→35%). Differences between simulation and practice (e.g., 20 measured packets per cycle vs. 14 intended) are traced to firmware-level retries or fragmentation and realistic Radio Frequency (RF) impairments (fading, motion), not to flaws in the scheduling design. The results show that gateway pre-aggregation and a minimal discovery overlay provide a practical path to reliable DtS uplinks on resourceconstrained radios, and they highlight concrete radio-engineering factors (antenna gain or placement, cabling, mounting stability) for robust deployments and future orbital campaigns.

Grantor dc:publisher

Stellenbosch : Stellenbosch University

Year dc:date.issued

2026

Author dc:creator

• Msonkho, Mayamiko Mark

Advisor dc:contributor.advisor

• Barnard, Arno

Language dc:language.iso

en

Repository record dc:identifier.uri

https://scholar.sun.ac.za/handle/10019.1/136137

OAI identifier oai:identifier

oai:scholar.sun.ac.za:10019.1/136137