區域性無線群播廣播服務之動態通道分配機制

Abstract

在無線群播廣播服務(Multicast and Broadcast Service；MBS)中，共用通道用來群播MBS內容給在基地台服務範圍內的使用者。使用共用通道會造成對專屬通道的干擾進而降低系統效能。在許多行動通訊網路標準中提出群播廣播服務區域技術用來改善系統效能以及降低對MBS使用者換手的延遲。在群播廣播服務區域技術中，一群基地台組成一個群播廣播服務區域，基地台們必須同時間利用相同的共用通道傳送相同MBS內容，用來降低共用通道所造成的干擾，並且當MBS使用者在相同群播廣播服務區域下不同基地台間移動，不需做換手動作。然而，當一個基地台下沒有MBS使用者時，持續使用群播廣播服務區域技術會造成基地台頻寬上的浪費。因此，這是一個重要的議題去決定什麼情況要去開啟群播廣播服務區域技術。為了更彈性的通道分配，我們提出兩個動態通道分配機制：DCA和EDCA。接著我們推導數學分析模型並開發模擬程式來觀察DCA和EDCA的效能。

In wireless Multicast Broadcast Service (MBS), the common channel is used to multicast the MBS content to the Mobile Stations on the MBS calls within the coverage area of a Base Station (BS), which causes interference to the dedicated channels serving the traditional calls, and degrades the system capacity. The Multicast Broadcast Service (MBS) zone technology is proposed in Mobile Communications Network (MCN) standards to improve system capacity and reduce the handoff delay for the wireless MBS. In the MBS zone technology, a group of BSs form an MBS zone, where the macro diversity is applied, BSs synchronize to transmit the MBS content on the same common channel, interference caused by the common channel is reduced, and the MBS MSs need not perform handoff while moving between the BSs in the same MBS zone. However, when there is no MBS MS in a BS enabling MBS zone technology, the transmission on the common channel wastes the bandwidth of the BS. It is an important issue to determine the condition for the MBS Controller (MBSC) to enable the MBS zone technology by considering the QoS for traditional calls and MBS calls. We propose two Dynamic Channel Allocation schemes: DCA and EDCA for more flexible channel allocation in an MBS zone. Analysis and simulation experiments are conducted to investigate the performance of DCA and EDCA.