在進階長期演進網路中裝置與裝置直連通訊與小型基地台之比較

Abstract

隨著智慧裝置蓬勃發展，越來越多樣的應用，例如社群網路服務，被產生與使用。然而現存的無線技術已經無負荷如此龐大的資料成長。因此長期演進技術被第三代合作夥伴計畫在版本八中提出來解決此問題。在版本十之後，長期演進技術被修改為進階長期演進技術並視為現今的第四代行動通訊。 在進階長期演進網路中，新的技術，例如裝置直連通訊與小型基地台，被提出來進一步解決爆炸資料的問題。裝置直連通訊能使鄰近的裝置直接傳輸，因此較少的無線資源需要被使用。至於小型基地台則被布建來提高較好的連線品質。 儘管裝置直連通訊與小型基地台都能提升進階長期演進網路中的資源使用效率，小型基地台獲得的關注是比較大的。主要原因是小型基地台並不需要通訊裝置在彼此的附近。然而小型基地台需要大量的裝置與布建的花費。對比起來，裝置直連通訊是一個較便宜的技術。因此同時考慮兩種技術可能可以使得整體花費是降低的，而且在網路中仍達到相同的服務品質。在這篇論文中，不同的參數，例如小型基地台的覆蓋率、裝置的通訊型態等，會被用來評估這兩種技術。模擬結果顯示透過裝置直連通訊的幫助，多達33%的減少在所需小型基地台數量上可以被達到就算大部分的連線都不是由鄰近裝置產生。

Thanks to the prevalence of mobile devices, various wireless applications and services such as online social networking and video streaming are developed and deployed. However, the continuous growth of data demand from these applications and services can no longer be supported by the existing wireless solutions. Long-Term Evolution (LTE) was proposed by the 3rd Generation Partnership Project (3GPP) in the Release 8 as a new network standard to solve this problem. After the Release 10, LTE becomes LTE-Advanced (LTE-A), which is regarded as the 4G standard nowadays. In LTE-A, new technologies, such as device-to-device (D2D) communication and small cells, are proposed to address the growing data demand. Take D2D communication as an example. Devices in the proximity of each other can communicate directly via a D2D link. Therefore, fewer radio resources are needed. Take small cell as another example. Small base stations (SBSs) can be deployed for increasing resource reutilization by providing better link quality. Although both D2D communication and small cells can improve resource utilization of LTE-A networks, the latter seems to attract more attentions since communicating UEs are not limited to be in the proximity of each other. However, deploying SBSs incurs a substantial amount of equipment and deployment expenses. Compared with small cells, D2D communication is a ``cheaper solution'. Therefore, joint consideration of both technologies may reduce the overall cost while the same performance is achieved. In this thesis, different parameters, such as small cell coverage ratios, traffic patterns of UEs, etc., are used to evaluate both technologies. Our simulation shows that with the help of D2D communication, up to 33% reductions in term of the number of SBSs deployed can be achieved even when most communication links are not proximity links.