2011 YÜksek lisans tez özetleri

Advanced Signal Processing Algorithms for New Generation Wireless Communication Systems

The increasing demand is gradually continuing for the data rate in the new generation wireless communication systems. One of the most important problems to meet this demand is the deep-fading effect of occurring in the channel. One of the best ways to reduce the effect of occurring in the channel fading is taking advantage of diversity techniques. Space Time Block Codes (STBC) digitally modulated signals are on the receiver and / or the transmitter by using multiple antennas in space diversity, the diversity of the different time intervals by sending codes that are capable of providing orthogonality. Independent channels with diversity without compromising bandwidth signals encoded in one of the other channel to the recipient even if the exposure to the deep reaches of the system fading performance increases.

However, these codes are designed for the flat fading channels. The codes have been envisaged to be combined with the Orthogonal Frequency Division Multiplexing (OFDM) systems to work at frequency selective channels. Thus, these integrated system can obstruct to Inter Symbol Interference (ISI) that occuring at wireless communication channels and it can balance at receiver by simply.DinleyinSAyrıntılı sözlüğü görüntüleRecently, these systems are combined with Code Division Multiple Access (CDMA) method to serve multiple users at the same time.

In the literature, the combination of OFDM and CDMA systems is known as multiple carrier (MC) so these integrated system is called as STBC-MC-CDMA. However, for detected of sending data series that is needed to channel frequency response at the receiver of system. Channel estimation methods proposed for STBC-MC-CDMA systems are very important for the new generation wireless communication systems. For this reason, new channel estimation methods will be proposed for STBC-MC-CDMA systems in the planned thesis.

Expectation maximization algorithm (EM) converges to maximum likelihood (ML) estimation that is very difficult to directly calculate , and an iterative algorithm running in parallel.In the literature, EM algorithm is applied to various communication systems for channel estimation. Algorithm consists of two phases that are the expectation step and maximization step. However, for the implementation of the algorithm the suitable signal model needs to be brought.In scope of this thesis, MC-CDMA systems code combining with STBC which is designed for two transmitter and one receiver systems, will be created the signal model for uplink and implemented the channel estimation with EM algorithm. The final channel observer’s achievement of mean square error (MSE) will be examined at typical urban (TU) channel within the proposed project of the COST 207.

  

AYDIN Çağatay

Danışman : Prof. Dr. Sıddık YARMAN

Anabilim Dalı : Elektrik-Elektronik Mühendisliği

Mezuniyet Yılı : 2011

Tez Savunma Jürisi : Prof. Dr. Sıddık YARMAN

Prof. Dr. İlhan KOCAARSLAN

Prof. Dr. Aydın AKAN

Prof. Dr. Hakan Ali ÇIRPAN

Yrd. Doç. Dr. Aysel ERSOY YILMAZ