階層式蜂巢式系統架構雖提供更具彈性的容量規劃，但是卻產生大量換手的問題。而大量的換手必須經過頻道、資料甚至於網路的交換，在交換的過程中會造成系統的負擔、降低系統的效能。而速度感應策略(Speed-Sensitive; SS)因可降低換手機率，而被廣為討論。但是一些系統的問題：負載不平衡問題、基地台(Base Station; BS)服務故障問題、基地台連結錯誤問題。皆會導致SS策略無法有效的在階層式系統下運作。因此本研究針對SS策略，提出一個容錯式多媒體效能提升策略，能自適性的調整所能使用的頻道數量，並可以容忍B服務、連結發生故障，確保系統的容量。模擬結果也顯示本策略可以大量提升SS策略的效能。

Hierarchical cellular networks that employ microcells with overlaying macrocells have been proposed to increase the traffic-carrying capacity and circuit quality. A major drawback is that a large number of handoff procedures usually take place when the calls cross the cell boundary. The large number of handoffs will increase the system overheads, such as channel switch, data switch, and even network switch. Accordingly, the speed-sensitive (SS) strategy that can decrease the handoff probability was applied. However, some system problems such as the imbalance of the traffic loads with the occupied bandwidth, base stations (BSs) failed to provide wireless communication service, or the wired link failures which will lessen the traffic-carrying capacity of the SS strategy. This study proposes a fault-tolerant multimedia capacity enhancement strategy for the SS strategy. When there are variations in traffic, our strategy can adapt the system channels to the traffic loads among BSs. When a BS fails to provide wireless communication service, its occupied channels cannot be used to provide services. Our strategy can revoke the occupied channels of the failed BS and reallocate to other BSs used to provide services. The reduction of the system capacity will be light. Moreover, the previous studies for the bandwidth scheduling problems are based on the message exchange among BSs by the wired networks to collect the necessary information. Therefore, the wired link failure will cause the bandwidth scheduling strategies to be inactive. Our strategy can tolerate the wired link failures to enhance the system capacity. Furthermore, the simulation results are presented to confirm that the proposed strategy is efficient to handle the multimedia traffic for the SS strategy.