Receiver design for a class of new pulse shapes for cpm signals

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Elektrik ve Elektronik Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2012

Öğrenci: BİLAL UĞURLU

Danışman: YALÇIN TANIK

Özet:

Recently, a study on obtaining better Euclidean distance for CPM (Continuous Phase Modulation) signals that fit well-known GSM spectral envelope has been carried out, and significant performance improvements were obtained. Two new pulse shapes, which are represented using 8th degree polynomials, were optimized to give the best error performance under the constraint that the PSD stays below GSM spectral standards. However, the approach uses parameters that cause the number of states to increase considerably, and thus yielding high complexity for receiver implementation. In this thesis, a study on finding a feasible receiver design that can provide a performance with acceptable degradation but affordable complexity is carried out for those new pulse shapes. After a survey about complexity reduction techniques, a decision is made to go on with a receiver structure based on Laurent Decomposition (LD) of phase modulated signals. Unlike other complexity reduction techniques, usage of LD based receivers permits reduction in both the number of matched filters and trellis states. Throughout the study, different numbers of matched filters and trellis states were used in LD based receivers for the new pulse shapes, and good results are obtained. For the pulse shape with pulse length L = 3, about a gain of 0.93dB in power is achieved by only 2 matched filters and 14 trellis states. For the case where L = 7, approximately a gain of 2.25dB is achieved with only 8 matched filters and 56 states, whereas 896 matched filters and 448 states are needed in the optimum case without complexity reduction.