Why did standards such as GSM and TDMA flourish before?

/in /by

Advanced 3G systems like LTE and 802.16e (WiMax) use OFDM. So do all potential 4G systems like LTE-Advanced and 802.16m. Even digital video broadcasts are now OFDM. Prior 3G standards, like UMTS and EVDO, predominantly used CDMA.( 3-4 paragraphs)

Why has this shift occurred?
Do you feel it is for the better?
What specific cross-layer optimizations are unique to OFDMA?
How have these affected this migration?
Why did standards such as GSM and TDMA flourish before?
Would a different solution have made better sense?
â—¦What trends do you see?APA format
Part B

Different access methods, such as OFDMA, SDMA, TDMA, CDMA, and FDMA, rely on cross-layer optimization to different degrees. The most common cross-layer issues are scheduling modulation type and setting power control. Complete the following for your assignment:

Describe the advantages of each access method in doing cross-layer optimization correctly.
What are the costs of doing it poorly? (2-3 pages) APA Format