No abstract

No abstract

In this work we investigate the use of a known symbol sequence -a so-called unique word (UW) -instead of the well-known cyclic prefix (as it is used in OFDM (Orthogonal Frequency Division Multiplexing) systems) for a single carrier system with fiequency domain equalization (SCFDE). The considered SCFDE system is similar to the one proposed in the IEEE 802.16.3~ target group. It is shown that the UW fulfils the theorem of cyclic convolution required for the eacient implementation of the SC/FDE structure. We will elaborate on the advantages that result for equalization, channel estimation, and synchronisation. Compared to the advantages, the disadvantages in terms of BER behaviour and bandwidth efficiency are rather modest.

Abstract. In this work we compare an OFDM (Orthogonal Frequency Division Multiplexing) system and a SC/FDE (Single Carrier System with Frequency Domain Equalization) system in terms of their BER performance, channel estimation techniques, bandwidth-efficiency and other design parameters. In both systems an estimation of the channel transfer function is needed for equalization purposes. Different frequency domain based channel estimation techniques for both systems are presented and compared. BER-simulations have been performed for channel-coded data in typicd indoor multipath environments. The parameters of both systems are adapted to the Hiperlad and IEEE 802.1 la standards. It will be pointed out that OFDM shows slight advantages when taking the BER performance into account, while the SC/FDE system exhibits advantages in terms of signal processing complexity. Finally a combination of OFDM and SC/FDE is described that exhibits significant advantages.

This paper deals with the concept, the implementation and the verification of an automatic impedance matching circuit for NFC antennas with a frequency of 13.56 MHz. Besides an introduction to manual tuning and its issues, the fundamental components of an automatic tuning system are outlined. A lab-scaled prototype is built and demonstrated. In the end, the successful operation of this system is tested with several different antennas.