Briefly describe the evolution of cellular mobile wireless communications, from the First Generation (1g) systems to Fourth generation (4g), providing details on each system, the typical frequency bands used, and main services provided, data throughput, etc. 12 Marks b) Describe with the aid of a diagram the basic topology of a GSM (2nd generation) network, showing how a Mobile Station (MS) will interface with the Public Switched Telephone Network (PSTN). 6 Marks c) Draw a diagram of the UMTS network architecture and briefly explain what the acronym UTRAN stands for and what it consists of. In your explanation use and very briefly define the terms: RNS, RNC, Iub and Node B.