OE-7.5 Multiple Access Techniques & Wireless Standards
You can compare FDMA, TDMA, CDMA, OFDMA and SDMA and the FDD/TDD duplexing choice, and describe GSM architecture along with GPRS and EDGE features.
Each multiple-access scheme divides a different resource - frequency, time, code, subcarrier, space - and once you see that, the comparison table writes itself. Duplexing is a separate question from access, and confusing the two is the standard error here. GSM is worth studying as a concrete case even though it is being retired: its architecture of base station, controller and switching centre is the skeleton later generations kept.
Work through these
Duplexing: FDD versus TDD
How the two directions of a conversation are separated, in frequency or in time. It is the first architectural choice a system makes and it constrains everything after.
FDMA and TDMA
Dividing users by frequency and by time slot, which is what the first two generations did. Comparing them is the point rather than either alone.
CDMA
Dividing users by code instead, so everyone transmits at once. It is conceptually the strangest of the three and the one that made the third generation possible.
OFDMA and SDMA
Dividing by subcarrier and by space, which is what current systems do. Both depend on ideas from the previous topic, so this item is where that work pays off.
GSM services and features
What the second-generation system offered a user, which is more than voice and less than you remember. It grounds the architecture in the next item.
GSM system architecture
The blocks of a real network and what each does. It is the most concrete thing in this course and worth being able to draw from memory.
GSM radio subsystem
The radio end of that architecture in detail. The frame structure is where the multiple access ideas above become a real specification.
GPRS and EDGE features
How data was added to a voice network, in two steps. It is a good case study in extending a system that was not designed for what you now want.
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