在IEEE 802.11aa重疊服務集下的可調式視訊串流

Abstract

在基於服務品質的服務集之下，無線存取點有權力去調控傳輸機會與排程優先性。當有資料流想要傳輸時，傳送端需要提供資料流的資訊，並且與無線存取點交涉以獲取保證頻寬。然而，802.11規範缺少從無線存取點發起的重新交涉機制，此機制用以確保在頻道狀況變動時能夠調整保證頻寬大小。在重疊服務集的環境中，無線存取點無法直接對在不同服務集的傳送端下命令。重疊服務集管理提供無線存取點一些方式，可用以和其它無線存取點交涉來分配頻道資源，以降低封包遺失機率。可調式視訊編碼擁有彈性的特性，但是仍需要可重覆交涉的機制來發揮此優點。重疊服務集管理提供無線存取點更多資訊來獲取頻道狀況。這篇論文的主要目標是提出一個交涉機制，在重疊服務集之下的可調式視訊串流可用此機制來嶄露彈性的優點。

In a QoS BSS, an access point (AP) has authority to control transmission opportunities and scheduling priorities. When there are traffic streams which want to be transmitted, stations need to provide information about the streams and contract with the AP to earn guaranteed bandwidth. However, the 802.11 standard lacks a renegotiation mechanism initiated by the AP which allows to adapt guaranteed bandwidth for fluctuations of channel condition. In Overlapping Basic Service Set (OBSS) environment, APs cannot command stations in different BSSs directly. OBSS management provides methods that APs can negotiate with others to allocate channel resource, and packet dropping probability would be reduced. Scalable video coding has a flexible property, but it needs a renegotiation mechanism to develop the advantage. OBSS management provides APs more information to know channel condition. The main goal of the thesis is to propose a negotiation mechanism by which scalable video streaming can exhibit flexibility advantage in OBSS environment.