Understanding GSM Standard — Lesson 2

This lesson covers the fundamentals of wireless communications, focusing on the Global System for Mobile Communications (GSM) standard. It provides an in-depth understanding of GSM, its architecture, and its functioning. The lesson also discusses the hierarchical nature of GSM, the identifiers used in the system, and the role of the Subscriber Identity Module (SIM) card. It further explains the modulation techniques used in GSM and the reasons for migrating to Code Division Multiple Access (CDMA) for third-generation mobile systems. For instance, an illustrative example related to the lesson is how GSM uses a combination of Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA) for efficient communication.

Video Highlights

01:19 - Introduction to wireless networks and brief outline of the lecture
03:34 - Discussion on the architecture of the GSM network and its hierarchical structure
06:14 - Explanation of the GSM network's identifiers and addresses
13:55 - Overview of the GSM network architecture, including the mobile station, base station subsystem, and network and switching subsystem;
35:14 - Discussion on the modulation for GSM, specifically Gaussian minimum shift keying
39:58 - Explanation of the multiple access for GSM, using a combination of FDMA and TDMA
42:16- Discussion on the disadvantages of GSM and the ongoing debate about the third generation mobile standard
49:56 - Conclusion of the lecture with a summary of the topics covered

Key Takeaways

- GSM is a set of ETSI standards specifying the infrastructure for a digital cellular service.
- GSM uses a hierarchical structure, including elements like the mobile switching center, location area, and base station controller.
- The SIM card in GSM is a smart card that identifies the terminal and allows access to subscribed services.
- GSM uses Gaussian Minimum Shift Keying (GMSK) for modulation.
- GSM uses a combination of FDMA and TDMA, making it slightly inefficient due to the need for frequency guard bands and time slot guards.
- The third-generation mobile systems are moving towards CDMA due to its greater system capacity and optimal usage of bandwidth.