在未來的通信網路中，需要支援高密度通訊設備的傳輸並同時保證足夠的資料傳輸率，近幾年，無細胞網路的架構被提出，其優點包括有效提升傳輸覆蓋率以及允許網路中的用戶同時被周圍多個合作傳輸點服務。不同於第四代通訊系統使用的允諾上行傳輸，我們考慮使用無允諾上行傳輸方式來減少用戶的時間延遲以及降低信令交換產生的額外資源，然而，其缺點為用戶間若同時傳輸極可能導致碰撞問題，增加傳送過程的錯誤率，為了解決此問題，我們使用稀疏碼多重接取技術，利用多重接取碼的正交性，允許多用戶在同一資源下能夠同時進行上行傳輸。本篇論文使用隨機幾何的方式分析競爭型稀疏碼多重接取在各場景中的效能，包括單傳輸點接收以及多傳輸點合作接收的場景，分析使用者與傳輸點間的連線品質以及區域頻譜使用率，推導的理論值與模擬結果會在論文中被展示及驗證，並且會在各接收場景針對不同的參數進行深入的數據探討。

Future wireless networks are required to support massive connectivity and also achieve high data rates and extended coverage. Cell-free (CF) network has been proposed in the recent years to explore macro diversity whereby each user equipment (UE) in the network can be served by multiple surrounding access points (APs) cooperatively. In addition, grant-free sparse code multiple access has been considered as a promising technique for massive connectivity. In this work, we investigate three uplink reception schemes, namely single AP, two Nearest AP and restricted strongest clustering, which are different in the way of AP clustering. We analyze the performance of each reception scheme by using the approach of stochastic geometry. The coverage probability and area spectral efficiency (ASE) of each scheme are derived theoretically. Simulation results are presented to verify the accuracy of theoretical analysis and also demonstrate the performance of each reception scheme in cell-free uplink SCMA.

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