具有保留頻道及有限佇列的蜂巢式行動通訊系統之性能分析

Abstract

地台致使通訊呼叫之訊號強度下降時，為維持通訊品質，必須將呼叫交遞 □j的頻道。然而，由於蜂巢式行動通訊系統其頻道數量的限制，交遞呼 叫將因無法取得頻道而導致通訊中斷。為求降低通訊中斷的機率， W道予 交遞呼叫所專用，並設置交遞與新建呼叫的有限佇列 堜I叫的阻絕機率不 致過高，且欲探討其與通訊中斷機率之性能交換(trade吾人於另一系統模 型中，對於新建與交遞呼叫皆分別設置其保留頻道。 ^人利用佇列觀察的 狀態變遷特性，以簡易的反覆矩陣求解法來取代計算複雜度呈指數擴增的 Mason's吾人將行動台依其通訊中的呼叫個數來分類，以分析 暋D。由分 析結果所示，保留頻道與有限佇列兩者中，前者對於 □剪蒫菕F而新建呼 叫保留頻道的作法較適用於蜂巢居留時間較大以及行動_系統。 When a mobile moves away from the base station, the receiveddecreases. In order to maintain the quality of communication service, thee handed off to another idle channel on which the received power level is higher.e of limited channels of a cellular mobile communication system, the handoff call mightided with a channel and be forced to terminate before completion. Forced terminationsy users to be interruptions of service. The phenomenon is considerably more obtrusive than new- callhould therefore be avoided as much as possible. In this thesis, an analytical model with guard channelshandoff calls, and with finite handoff-call queue and finite new-call queue, is presented. In addition, in order to keep the new-call blocking probability not too high explore the trade-off between termination probability andng probability, another analytical modal with new-call and handoff-call guard channels is presented. In this thesis, we utilize the transition characteristics of from the aspect of queue observer to replace Mason's formula, by the complexity of calculation increases on an exponential rate, simple iterative matrix computations. Furthermore, we classify according to the number of calls in progress to analyze the handoff problem. From the numerical results, it is found that have more notable effects on system performance than finitet new-call guard channels is suitable for a system in which the is longer and the number of mobiles is fewer.