本碩士論文的內容包含兩個議題。在第一個議題中，我們針對第三代行動通訊系統 UMTS (Universal Mobile Telecommunication System)所使用的 WCDMA (Wideband Code Division Multiple Access) 存取技術，設計一個正交可變展頻因子 (Orthogonal Variable Spreading Factor, OVSF) 碼樹的管理機制。在這個機制中，我們採用 3GPP (The Third Generation Partnership Project) 訂定之第三代行動通訊系統 UMTS 的規範中所定義的多媒體型態，包括 Conversational 、 Streaming 、 Interactive 和 Background ，考量多媒體服務的特性，適當的分配有限資源 OVSF 碼；另外，為了因應多媒體多元化的要求，我們也加入動態資源分配 (Dynamci Resource Allocation， DRA) 機制，進一步達到多媒體服務品質 (Quality of Service， QoS)的保証，而且經由程式模擬，除了可以看到加入 QoS 考慮後，我們的機制中各服務之新進呼叫阻斷率 (New Call Blocking Probability) 的表現，數據中也顯示我們的機制中重新配置的策略可以大大減少重新配置的次數。第二個議題中，我們將利用 Vovida 提供的 Vovida Open Communication Application Library (VOCAL) 開放原始碼，建立功能完整的 SIP (Session Initiation Protocol) User Agent (UA)。議題中我們將對 SIP 做簡單的介紹，同時也會把我們在實作 SIP UA 過程中，不管是針對在 VOCAL 原始媽中所發現的問題或是我們額外加強的功能，詳細說明問題的原因及相關解決方法，並且透過和 VOCAL SIP Server 所建立的 SIP 網路，進行包括功能、與它家廠商 UA 軟體相容性、以及和 PSTN 網路的連通狀況測試，建立更完整的實驗室 VoIP 平台。

This thesis is composed of two topics. In the first topic, we design a scheme on the orthogonal variable spreading factor (OVSF) code tree management for the wideband code division multiple access (WCDMA) in the universal mobile telecommunication system (UMTS). In this scheme, we take the multimedia (including conversational, streaming, interactive, and background services) charactereistics defined by 3GPP (the third generation partnership project) and dynamic resource allocation (DRA) into consideration to make the management efficient and satisfy different quality-of-service (QoS) requirements requested by diverse multimedia applications. Through simulations, we demonstrate that the proposed scheme can not only adequately take care of QoS requirements but also significantly reduce the number of code reassignments, making it charming and more suitable for the real and complicated system. In the second topic, we adopt the open source codes of Vovida open communication application library (VOCAL) provided by Vovida to implement a SIP-based user agent (UA). For this topic, we first introduce how SIP works in voice over IP (VoIP) networks. Then, we solve the problems found in the original source codes and enhance its functions. Through the system test with the VOCAL SIP servers, we successfully show that the enhanced SIP UA works well with other UAs and PSTN networks.

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