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In this paper, five novel schemes based on greedy algorithm are proposed to reduce the peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. For each proposed scheme, a simple transformation is performed on the partial transmit sequences in an iterative fashion to lower the PAPR. Computer simulations results show that all the proposed schemes can achieve PAPR reductions, but the performances of the PAPR reduction are different. To further evaluate their PAPR reductions, we compare the proposed schemes with the iterative flipping scheme. The results show that when the number of subblocks is not large, some of the proposed schemes can offer better PAPR reduction performance than the iterative flipping scheme with comparable computational complexity. [ABSTRACT FROM AUTHOR]

As a loudspeaker's physical size decreases, its ability to reproduce low frequencies is hindered. In this paper we propose a method of creating virtual bass using an efficient frequency tracking algorithm. The proposed algorithm has low computational complexity but excellent performance. The results of computer simulations and subjective tests are presented to validate the algorithm. [ABSTRACT FROM AUTHOR]

In this paper, we suggest a synchronization receiver for MIMO-OFDM based mobile broadcasting system. A MIMO-OFDM receiver with algorithms for tracking of residual frequency offset (RFO) and sampling frequency offset (SFO) is designed and simulated. The proposed synchronization and compensation schemes are applied to IEEE 802.16e WiMAX and its performance is investigated by computer simulations in terms of mean square error (MSE) and bit error rate (BER). The proposed RFO and SFO estimator has a fast convergence and a small residual degradation even for high speed mobile station. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel postprocessing technique based on the theory of the projection onto convex sets (POCS) in order to reduce the blocking artifacts in digital high definition television (HDTV) images. By detecting and eliminating the undesired high-frequency components, mainly caused by blocking artifacts, we propose a new smoothness constraint set (SCS) and its projection operator in the DCT domain. In addition, we propose an improved quantization constraint set (QCS) using the correlation of DCT coefficients between adjacent blocks. In the proposed technique, the range of the QCS is efficiently reduced as close to the original DCT coefficient as possible to yield better performance of the projection onto the QCS. Computer simulation results indicate that the proposed schemes perform better than conventional algorithms. Furthermore, we introduce a fast implementation method of the proposed algorithm. The conventional POCS-based postprocessing techniques require the forward/inverse discrete cosine transform (DCT/IDCT) operations with a heavy computational burden. To reduce the computational complexity we introduce a fast implementation method of the proposed algorithm that does not perform DCT/IDCT operations. Estimates of computation savings vary between 41% and 64% depending on the task. [ABSTRACT FROM AUTHOR]

In this paper, we propose a power-efficient and QoS (Quality of Service) -aware MAC (Medium Access Control) scheduling algorithm for Bluetooth scatternet. If the inter-piconet scheduler in a bridge node between piconets operates simply by the Round Robin (RR) policy, a number of time slots may be wasted due to the guard time for piconet switching and the exchange of POLL-NULL packets. To overcome the link wastage problem in Bluetooth scatternet scheduling, several algorithms have recently been proposed. Although they can provide all of the links of a bridge node with fair service opportunities, they may cause waste of wireless resources since different Bluetooth devices may have various traffic characteristics. In addition, since Bluetooth devices are often required to operate under limited battery capacity, the number of unnecessary piconet switching has to be minimized for the power-efficient operation of a Bluetooth scatternet. Therefore, we propose a mechanism to support the power-efficient operation of a Bluetooth scatternet while guaranteeing various QoS requirements of Bluetooth devices. The proposed algorithm is compliant with the current Bluetooth specification, and we demonstrate its improved performance via simulations. [ABSTRACT FROM AUTHOR]

In this paper, a technique based on the auto correlation Junction is proposed to estimate the Doppler spread in Rayleigh fading channels for mobile OFDM systems. It is simply implemented with the cyclic structure of OFDM symbols, and any other additive data and pilots need not to be inserted into the common OFDM symbols. This algorithm can be applied directly to the OFDM system with transmit diversity (TD) and to MIMO OFDM systems. Computer simulation results are included to support our developments in the terms of mean estimation value and mean square error. [ABSTRACT FROM AUTHOR]

The robust reception of network parameters is a very important issue for the successful deployment of mobile infotainment services, particularly in fast-moving environments. An infrastructure broadcasts service access-related messages to consumer devices. These access messages critically affect the connectivity between the consumer devices and service providers. This paper proposes an algorithm to increase the connectivity by collaborating consumer devices to share access information messages. The consumer device that receives the access message retransmits the message by attached it to its beacon message. This is performed only when there are neighboring consumer devices that did not receive the message. This paper also proposes an extended beacon message for this purpose. The proposed algorithm was evaluated with computer simulations. [ABSTRACT FROM PUBLISHER]