與雲計算類似，邊緣計算和霧計算技術更接近用戶，提供類似的服務，但規模更低且分佈更廣。我們將這些組合成一個單一的聯邦來擴展計算環境，其中計算請求可以在它們之間有效地卸載。由於現有卸載模型僅限於單跳和單向垂直場景，我們提出了聯合雲、邊緣和霧系統的通用卸載模型，以提供兩跳、水平和雙向垂直卸載。我們制定了一個優化問題，利用延遲來做為限制去最小化總成本，並使用模擬退火演算法作為其解決方案。我們的結果顯示出，與一跳卸載相比，兩跳可以節省10%-20%的成本。水平和雙向卸載比起不水平卸載和單向垂直卸載分別節省近12%和20%的成本。

Similar to cloud computing, edge and fog computing technologies evolve closer to users, providing similar services but on a lower, yet more widely distributed scale. Combining these into a single federation expands the computing environment where computing requests could be offloaded effectively among them. Since existing offloading models are limited to single-hop and unidirectional vertical scenarios, we propose a generic offloading model of federated cloud-edge-fog systems to provide two-hop, horizontal, and bidirectional vertical offloading. We formulate an optimization problem to minimize the total cost with latency as a constraint and apply simulated annealing as its solution. Our results show that 10%-20% of costs can be saved with two-hop compared to one-hop offloading. With horizontal and bidirectional offloading, nearly 12% and 20% in costs can be saved, compared to no horizontal offloading and only unidirectional vertical offloading, respectively.

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