PAPR REDUCTION IN LAYERED-OFDMA OF LTE-A: A NEW PRECODING BASED ADAPTIVE UPLINK RA SYSTEM

This paper presents a new precoding based adaptive multi-carrier/single-carrier (MC/SC) uplink radio-access (RA) system with improved peak-to-average power ratio (PAPR) for layered orthogonal frequency division multiple access (Layered-OFDMA) of long term evolution advanced (LTE-A). The Discrete-Cosine transform (DCT) precoding is applied before subcarrier mapping and IFFT to reduce the high PAPR of the MC uplink system. The conventional SC system is implemented to sustain all the functionalities offered by the release 8 LTE. Extensive computer simulations have been performed to analyze the PAPR of the proposed system. The computer simulation results show that, the PAPR of DCT precoded MC signals is approximately same as that of conventional SC signals

A NEW DISCRETE HARTLEY TRANSFORM PRECODING BASED INTERLEAVED-OFDMA UPLINK SYSTEM WITH REDUCED PAPR FOR 4G CELLULAR NETWORKS

High peak-to-average power ratio (PAPR) reduction is one of the major challenges in orthogonal frequency division multiple access (OFDMA) systems since last decades. High PAPR increases the complexity of analogue-to-digital (A/D) and digital-to-analogue (D/A) convertors and also reduces the efficiency of RF high-power-amplifier (HPA). In this paper, we present a new Discrete- Hartley transform (DHT) precoding based interleaved-OFDMA uplink system for PAPR reduction in the upcoming 4G cellular networks. Extensive computer simulations have been performed to analyze the PAPR of the proposed system with root-raised-cosine (RRC) pulse shaping. We also compare simulation results of the proposed system with the conventional interleaved-OFDMA uplink systems and the Walsh-Hadamard transform (WHT) precoding based interleaved-OFDMA uplink systems. It is concluded from the computer simulations that the proposed system has low PAPR as compared to the conventional interleaved-OFDMA uplink systems and the WHT precoded interleaved-OFDMA uplink systems

ON THE PAPR REDUCTION IN OFDM SYSTEMS: A NOVEL ZCT PRECODING BASED SLM TECHNIQUE

High Peak to Average Power Ratio (PAPR) reduction is still an important challenge in Orthogonal Frequency Division Multiplexing (OFDM) systems. In this paper, we propose a novel Zadoff-Chu matrix Transform (ZCT) precoding based Selected Mapping (SLM) technique for PAPR reduction in OFDM systems. This technique is based on precoding the constellation symbols with ZCT precoder after the multiplication of phase rotation factor and before the Inverse Fast Fourier Transform (IFFT) in the SLM based OFDM (SLM-OFDM) Systems. Computer simulation results show that, the proposed technique can reduce PAPR up to 5.2 dB for N=64 (System subcarriers) and V=16 (Dissimilar phase sequences), at clip rate of 10-3. Additionally, ZCT based SLM-OFDM (ZCT-SLM-OFDM) systems also take advantage of frequency variations of the communication channel and can also offer substantial performance gain in fading multipath channels

TRANSFORM DOMAIN SLICE BASED DISTRIBUTED VIDEO CODING

Distributed video coding depends heavily on the virtual channel model. Due to the limitations of the side information estimation one stationary model does not properly describe the virtual channel. In this work the correlation noise is modelled per slice to obtain location-specific correlation noise model. The resulting delay from the lengthy Slepian-Wolf (SW) codec input is also reduced by reducing the length of SW codec input. The proposed solution does not impose any extra complexity, it utilizes the existing resources. The results presented here support the proposed algorithm

Novel Precoding Based PAPR Reduction Schemes for Localized OFDMA Uplink of LTE-A

High Peak to Average Power Ratio (PAPR) reduction is still a major challenge in Orthogonal Frequency Division Multiple Access (OFDMA) systems. The subcarrier mapping in OFDMA can be done in two modes, Localized mode and Distributed mode. The Localized mode is more suitable for the practical implementations than the Distributed mode due to its low sensitivity against the imperfect power control, phase noise and Inter Carrier Interference (ICI). In this paper, we propose two novel precoding based Multi-Carrier (MC) Multiple Access (MA) techniques for PAPR reduction, ZadoffChu precoding based Localized-OFDMA (L-OFDMA) technique and Generalized Chirp Like (GCL) precoding based L-OFDMA technique for L-OFDMA uplink systems of upcoming Long Term Evaluation-Advanced (LTE-A) system. These techniques are based on precoding the constellation symbols with Zadoff-Chu precoder and GCL precoder. The proposed techniques can reduce PAPR up to 6.5dB for L-OFDMA. It is noticeable from the computer simulation results, that the PAPR of our proposed precoding based MC systems have approximately equal PAPR as compared to the PAPR of competing technology called Localized Single Carrier Frequency Division Multiple Access SC-FDMA (LFDMA) system. LFDMA is implemented in release 8 of Long Term Evaluation (LTE). Additionally, these precoding based PAPR reduction techniques also takes the advantage of the frequency variations of the communication channel and can also offer substantial performance gain in fading multipath channel

BEST FIT MODELS TEST FOR THE VIRTUAL CHANNEL IN DISTRIBUTED VIDEO CODING

Wyner-Ziv (WZ) video coding – a particular case of distributed video coding (DVC) – is a new video coding paradigm based on two major Information Theory results: the Slepian-Wolf and Wyner-Ziv theorems. Most of the solutions available in the literature, model the correlation noise between the original frame and the so-called side information by virtual channel. However most of the DVC solutions in the literature assume Laplacian distribution as noise virtual channel model, in this study we perform three goodness-of-fit tests, the Kolmogorov-Smirnov test and the Chi-Square test and log-Likelihood test to study the nature of the virtual channel. The results show that a mixture of 3 (or 4) mixture Gaussian model can best describe this virtual channel

A Heuristic Approach for Optical Transceiver Placement to Optimize SNR and Illuminance Uniformities of an Optical Body Area Network

The bi-directional information transfer in optical body area networks (OBANs) is crucial at all the three tiers of communication, i.e., intra-, inter-, and beyond-BAN communication, which correspond to tier-I, tier-II, and tier-III, respectively. However, the provision of uninterrupted uplink (UL) and downlink (DL) connections at tier II (inter-BAN) are extremely critical, since these links serve as a bridge between tier-I (intra-BAN) and tier-III (beyond-BAN) communication. Any negligence at this level could be life-threatening; therefore, enabling quality-of-service (QoS) remains a fundamental design issue at tier-II. Consequently, to provide QoS, a key parameter is to ensure link reliability and communication quality by maintaining a nearly uniform signal-to-noise ratio (SNR) within the coverage area. Several studies have reported the effects of transceiver related parameters on OBAN link performance, nevertheless the implications of changing transmitter locations on the SNR uniformity and communication quality have not been addressed. In this work, we undertake a DL scenario and analyze how the placement of light-emitting diode (LED) lamps can improve the SNR uniformity, regardless of the receiver position. Subsequently, we show that using the principle of reciprocity (POR) and with transmitter-receiver positions switched, the analysis is also applicable to UL, provided that the optical channel remains linear. Moreover, we propose a generalized optimal placement scheme along with a heuristic design formula to achieve uniform SNR and illuminance for DL using a fixed number of transmitters and compare it with an existing technique. The study reveals that the proposed placement technique reduces the fluctuations in SNR by 54% and improves the illuminance uniformity up to 102% as compared to the traditional approach. Finally, we show that, for very low luminous intensity, the SNR values remain sufficient to maintain a minimum bit error rate (BER) of 10−9 with on-off keying non-return-to-zero (OOK-NRZ) modulation format