tailieunhanh - GSM Networks : Protocols, Terminology, and Implementation - Chapter 13

Chất lượng hạn dịch vụ (QoS) có một ý nghĩa cụ thể về viễn thông. Nó đề cập đến khả năng sử dụng và độ tin cậy của một mạng lưới và dịch vụ của mình. Chương này nêu bật các ứng dụng có thể có của giao thức phân tích cho sự giám sát và phân tích chất lượng mạng lưới và trình bày các vấn đề mà các nhà khai thác mạng GSM thường xuyên phải đối mặt. Làm thế nào thiết bị thử nghiệm giao thức có thể được sử dụng để nâng cao chất lượng mạng?. | 13 Quality of Service The term quality of service QOS has a specific meaning in telecommunications. It refers to the usability and reliability of a network and its services. This chapter highlights possible applications of protocol analyzers for the supervision and analysis of network quality and presents the problems that GSM network operators most frequently face. How can protocol test equipment be used to improve network quality What errors occur most frequently in GSM and what are the root causes of those errors How can reliable and comparable routines for statistical analysis be developed This chapter focuses on answering those questions. Tools for Protocol Measurements In general there are three ways to determine the QOS of a GSM network Drive tests. Teams paid by the network operator drive on predefined routes in the network and periodically initiate calls. The results . unsuccessful handover low-quality audio dropped calls signal strength are transferred from the MSs to a dedicated PC where the respective data are available for postprocessing. This kind of measurement represents most closely the network quality as real subscribers experience it. The disadvantage however is that only a limited area and a small time window can be tested and the testing is extremely expensive. Real-time measurement tools for call quality like QVOICE 275 276 GSM Networks Protocols Terminology and Implementation belong to the same category but allow for a more objective judgment on the call quality. Protocol analyzers. Preferably at a central place protocol analyzers are connected to BTSs BSCs and MSCs over a period of time. Frequently these devices come with remote access capabilities which eases most configuration changes. Captured trace files can be uploaded to a central office for statistic evaluation. When problems are detected the trace file needs to be analyzed manually and more thoroughly. Measurements with protocol analyzers have the advantage that all captured