A synchronization technique for generalized frequency division multiplexing

Abstract

Generalized frequency division multiplexing (GFDM) is a block filtered multicarrier modulation scheme recently proposed for future wireless communication systems. It generalizes the concept of orthogonal frequency division multiplexing (OFDM), featuring multiple circularly pulse-shaped subsymbols per subcarrier. This paper presents an algorithm for GFDM synchronization and investigates the use of a preamble that consists of two identical parts combined with a windowing process in order to satisfy low out of band radiation requirements. The performance of time and frequency estimation, with and without windowing, is evaluated in terms of the statistical properties of residual offsets and the impact on symbol error rate over frequency-selective channels. A flexible metric that quantifies the penalty of misalignments is derived. The results show that this approach performs practically as state-of-the-art OFDM schemes known in the literature, while it additionally can reduce the sidelobes of the spectrum emission.

Improving GFDM Symbol Error Rate Performance using “Better than Nyquist” Pulse Shaping Filters

“…El filtro de conformación de pulso de Nyquist mejorado, se propone en la [19] en el contexto de modulaciones monoportadoras, para mejorar la sensibilidad de la inestabilidad temporal. El primer filtro de conformación de pulso, considerado en la [19], es la secante hiperbólica invertida (Fsech), cuya expresión en el dominio del tiempo, se da por ( )…”

“…El primer filtro de conformación de pulso, considerado en la [19], es la secante hiperbólica invertida (Fsech), cuya expresión en el dominio del tiempo, se da por ( )…”

“…Aquí, consideramos impulsos de tipo Xia, familia propuesta en la [18], y extensiones de esta familia de impulsos, propuesta en la [19] con el nombre " Better than Nyquist", donde presentamos el objetivo de alcanzar una alta tolerancia, contra el error temporal del símbolo, en un esquema de modulación monoportadora. Como sugerido en la [20], cuando los filtros de conformación de pulsos de Nyquist se consideran en la GFDM, se puede alcanzar una mejora en el rendimiento, a través de un intercambio de rol, de la variable independiente de la frecuencia con la variable independiente del tiempo, en la expresión formal, definiendo el pulso en coseno alzado.…”

GFDM Frame Design for 5G Application Scenarios

“…The preamble load is formed by a sequence of K on QAM symbols, which are repeated in each subsymbol. Tis preamble content creates a time-redundancy that can be exploited by the synchronization algorithm on the receiver side [32]. Tables III and IV summarize the frame parameters for each scenario and the achieved performance, respectively.…”

Improved Nyquist pulse shaping filters for generalized frequency division multiplexing

“…Improved Nyquist pulse shaping filters have been originally proposed in [20] to achieve higher tolerance to symbol timing error in single-carrier modulation schemes. As suggested in [21], when Nyquist pulse shaping filters are considered in GFDM a performance improvement can be achieved by exchanging the role of the frequency independent variable with that of the time independent variable in the formal expression defining the raised cosine pulse. The main advantage is that there is no overlapping in the frequency domain and, therefore, less interference is observed.…”