The main goal of next generation wireless systems is to provide multimedia communication with spectrally efficient communication. Most of the up-to-date systems have been standardised to use OFDM modulation which prevents inter-symbol interference and make use of parallel subcarriers. The large number of subcarriers helps to avoid the effects of fast fading by distributing channel coded informa...

A stimulus driver circuit for a micro-stimulator used in an implantable device is presented in this paper. For epileptic seizure control, the target of the driver was to output 30 µA stimulus currents when the electrode impedance varied between 20 and 200 kΩ. The driver, which consisted of the output stage, control block and adaptor, was integrated in a single chip. The averaged power consumpti...

Advanced forward error correcting (FEC) and modulation scheme basing on low-density parity-check codes (LDPC) and adaptive bit loading (ABL) procedure is investigated for WLAN physical layer (PHY) of IEEE 802.11a standard. The main intention of the present paper is to study influence of the advanced PHY algorithms on the WLAN throughput under the realistic deployment conditions, for which a har...

This paper proposes a new algorithm of adaptive subcarrier allocation and bit loading for simultaneous voice and data transmission in multiuser OFDM systems. The algorithm dynamically assigns the number of subcarriers and bits/per symbol on each subcarrier for each user in a single cell. To cope with the stringent delay requirement of voice service, the subcarriers with low channel gains are as...

In this paper, we consider a transmission system employing orthogonal frequency division multiplexing (OFDM) with bit-interleaved coded modulation and perfect channel state information at both transmitter and receiver. An adaptive bit loading scheme in combination with cyclic delay diversity and discontinuous Doppler diversity is proposed at the transmitter and iterative demapping and decoding ...

This paper presents a novel numerical technique to simulate the crack propagation process for inhomogeneous solids. The criteria of crack growth and path selection are expressed in terms of some simple functions of fracture energy and loading phase angle. The energy release rate and loading phase angle for mixed mode cracks are evaluated by the ®nite element method with a mesh-adaptive techniqu...