Studentische Arbeiten

Titel: Non-orthogonal Signaling over doubly dispersive channels employing multicarrier modulation
Typ:
  • Masterarbeit
Betreuer:
Status: abgeschlossen

Hintergrund

With the fast growing amount of devices which are to be connected to the Internet, future 5G wireless communication systems have to be able to support a very diverse type of traffics. In the road towards 5G, radical changes of various technologies are required to meet the increasing demand of data rate, capacity, latency and etc. Starting from the fundamental aspect of physical layer, the institute is looking into potential alternative waveform technologies to OFDM. One of 5G waveform candidates is  universal filtered multicarrier (UFMC). It can be seen as a generalization of filter-bank multicarrier (FBMC) and OFDM. Based on filtering a group of subcarriers, it combines the advantages of FBMC and OFDM, while avoiding its main drawbacks.

Problemstellung

OFDM is today's prominent modulation scheme, it is applied in various standards such as WLAN and LTE. However, it may not suit all requirements of the expected heterogeneous traffics in 5G. Recently, a novel multicarrier modulation scheme, UFMC, was proposed to enhance the performance of OFDM. One problem in wireless communcations is the so-called doubly dispersive channel, which causes not only dispersion in time but also in frequency. The time dispersion of wirelss channels is combated by inserting cyclic prefix in OFDM. The insertion of cyclic prefix protects OFDM symbols from intersymbol interference (ISI) at the expense of some loss of spectral efficiency. The other issue in OFDM is however the frequency dispersion (or Doppler effect), because of it's high out-of-band emission.

UFMC applies per sub-band FIR-filtering, thus it can be well-localized in frequency (more robust against frequency dispersion). For a better spectral efficiency, no guard band is inserted between successive symbols, thus more sensitive to time dispersion. However, UFMC has the degree of freedom to design the FIR-filter. The aim of this work is to obtain a well-designed FIR-filter for UFMC after passing through the doubly dispersion wireless channel.

Aufgabe

The tasks of this thesis involve:

  • implementation of doubly dispersion wireless channel
  • implement known algorithm of optimizing FIR-filter in UFMC
  • compare the performance of UFMC and OFDM under doubly-dispersive channels (different mobility of users and environment conditions)
  • quantify the optimization gain
  • Simulation in Matlab

 

This thesis can be accomplished in German or English.

Anforderung

 

  • Knowledge of signal processing, OFDM
  • Optimization theory is desirable

 

Kenntnisgewinn

  1. Digital Signal Processing
  2. Multicarrier modulation (UFMC,OFDM)
  3. Wireless Channels
  4. Optimization theory