{"id":{"repo_id":"stellenbosch","oai_identifier":"oai:scholar.sun.ac.za:10019.1/136137"},"canonical_url":"https://search.dev.ndltd.org/etd/stellenbosch/oai:scholar.sun.ac.za:10019.1/136137","repository":{"repo_id":"stellenbosch","name":"Stellenbosch University","base_url":"https://scholar.sun.ac.za/server/oai/request"},"display":{"title":"Integration of Wireless Sensor Network with CubeSat Satellite System for Enhanced Agricultural Monitoring","abstract":"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.","abstract_html":"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.","abstract_has_math":false,"creators":["Msonkho, Mayamiko Mark"],"institution":"Stellenbosch : Stellenbosch University","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Barnard, Arno"],"committee_chairs":[],"committee_members":[],"year":2026,"date_issued":"2026-03","date_published":"2026-03","updated_at":"2026-07-24T04:40:12Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholar.sun.ac.za/handle/10019.1/136137","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Barnard, Arno"]},{"key":"dc:contributor.other","label":"Dc Contributor Other","values":["Stellenbosch University. 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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."]},{"key":"dc:title","label":"Title","values":["Integration of Wireless Sensor Network with CubeSat Satellite System for Enhanced Agricultural Monitoring"]}]}],"canonical_facts":{"dc:contributor.advisor":["Barnard, Arno"],"dc:contributor.other":["Stellenbosch University. Faculty of Engineering. 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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."],"dc:identifier.uri":["https://scholar.sun.ac.za/handle/10019.1/136137"],"dc:language.iso":["en"],"dc:publisher":["Stellenbosch : Stellenbosch University"],"dc:title":["Integration of Wireless Sensor Network with CubeSat Satellite System for Enhanced Agricultural Monitoring"],"dc:type":["Thesis"]},"updated_at":"2026-07-24T04:40:12Z"}