OFDMA and SC-OFDMA

[minasaad]

I have a question about LTE multiple access technique.
In DL we use OFDMA, we increase the symbol time to overcome ISI, and in UL we use SC-OFDMA by modulating the whole subcarriers with the same info but with a small symbol duration… Now the ISI is back again in the UL. What do we do to overcome it then?

[marcelofb]

Hi @minasaad

Here you can find a good conversation, with possible answers:

What is ISI (Inter Symbol Interference) in LTE?

Introduction The development of modulation techniques allowed significant developments in mobile communications through the transmission of symbols carrying a large amount of information. However, there is a common problem in such systems: the interference inter symbols (ISI or Inter Symbol Interference). [image] Let us understand this today: what is the interference between symbols (ISI), existing in the LTE Systems, and also in any technology that uses symbols for the information transport…