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This paper proposes a new peak-to-average power ratio (PAPR) reduction technique called partial symbol transmission (PST) for OFDM systems. The proposed system selects the specific duration of each time-domain OFDM symbol which can achieve a promising PAPR, to transmit equal bits of data. Compared with the OFDM system using amplitude clipping, PST can obtain comparable PAPR performance and achieve...
A major drawback of orthogonal frequency division multiplexing (OFDM) is the high peak-to-average power ratio (PAPR) of the transmit signal which can significantly impact power efficiency and performance. In this paper we present a PAPR reduction technique which exploits the phase of the signal in the frequency domain. When used to extend a previous PAPR reduction technique developed by the authors,...
The next generation of wireless networks (4G) will use OFDMA (orthogonal frequency-division multiple access) technology on both forward and reverse links. In addition to high speed data services, these networks will also support voice using the voice over IP (VoIP) protocol. In this paper we focus on the capacity of VoIP service for the OFDMA uplink. Although resources allocated to users within a...
A maximum likelihood (ML) estimator of carrier frequency offset (CFO) based on virtual carriers is firstly proposed in [1]. Its main disadvantage is large computational amount. By IFFT and piecewise searching techniques, its complexity is significantly reduced. Simulation results in AWGN and Typical Urban (TU) channels show that the simplified ML estimator has low complexity and achieves the same...
The performance of a mobile radio system based on OFDMA is determined by the type of mapping of logical subchannels, which are allocated for data transmissions, onto the frequency channel. The mapping scheme affects the diversity both within and between the OFDMA subchannels. This paper provides a performance comparison of different subchannel mappings from MAC point of view by means of stochastic...
This paper have developed farther the method of constructing sparse parity-check matrix (H-matrix) with determinate systemic structure as well as designing practice recursive encoding algorithm of the low-density parity-check (LDPC) codes. It discovers that the LDPC codes based on the circulant-shifted permutation Q-matrix created by N-queens searching algorithm perform better than them based on permutation...
Based on Generalized Distributive Law (GDL), improved belief propagation (BP) algorithm in logarithm domain for M-ary APSK modulated Low-density parity-check (LDPC) code which can get a better tradeoff between error performance and decoding complexity is proposed. Also the Min-Sum approximation of the improved log-BP algorithm is deduced. Simulation shows that the improved log-BP and Min-Sum algorithms...
LDPC convolutional code (LDPC-CC) decoders are composed of processors, making them parallel in the iteration dimension. However, for time-varying LDPC-CCs, each individual processor is serial in the node dimension, hindering the throughput increase for such decoders. We propose a joint code-decoder design, which generates architecture-aware LDPC- CCs of good performance, as well as an LDPC-CC decoder...
This paper proposes a class of decomposable LDPC codes based on finite geometry EG(m, ps) over bandlimited AWGN channel. These LDPC codes defined as the origin LDPC codes are decomposed into a few small LDPC codes as component codes in multilevel coding. It is shown that the origin LDPC codes demand generic M-ary Min-Sum algorithm while the component codes only require a few binary Min-Sum algorithm...
Low-density parity-check (LDPC) codes offer a very powerful error correction technique which allows data transmission in wireless networks at rates near the channel capacity with arbitrarily low probability of error. In this paper, we design a class of linearly encodable LDPC codes with adaptive code rates, i.e. the code rate can be adapted according to channel conditions to maximize the total capacity...
Multi-Band Orthogonal Frequency Division Multiplexing (MB-OFDM) is a suitable solution to implementation of high speed data transmission in ultra wideband spectrum by dividing the spectrum available into multiple bands. The baseband of transmitter is one of the most important parts in MB-OFDM system. The structure of MB-OFDM system transmitter is introduced in this paper and the design of transmitter...
This paper presents a 2.4 GHz power amplifier driver used in a WLAN IEEE 802.11b/g transmitter front-end which employs a walking IF architecture. The power amplifier driver is implemented in a 50 GHz 0.5 mum SiGe BiCMOS technology. And it consists of a differential cascode amplifier stage, an emitter follower and a common-emitter amplifier. It dissipates 28 mA current under a 3.3 V power supply, and...
A novel SON (silicon-on-nothing)-LDMOS (laterally diffused MOS) with heavily doped buried layer (HDBL) beneath air layer is proposed for RF base-station power amplifier application. The characteristics of the proposed device are analyzed in terms of breakdown voltage, kink effect, and high frequency performance. With the device and circuit simulator Atlas, two-dimensional simulations are presented...
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