No abstract

No abstract

We propose an adaptive scheme of a differential codebook for temporally correlated channels. The codeword entries of the proposed codebook are selected among the set of M -PSK constellations and the values of M proposed in this paper are 8, 16, or 32. Firstly, we analyze mathematically how the optimal spherical cap radius of the proposed codebook is tracked. Then, we explain how to implement the proposed differential equal-gain codebook practically. Among the candidate differential codebooks designed for various temporal correlation coefficients, the proper codebook can be chosen (or switched) according to the temporal correlation coefficients of wireless channels. We assume that the correlation coefficients of the channels are known to the receiver and the properly (or optimally) chosen differential codebook can show the best system throughput performance. Monte-Carlo simulations demonstrate that the achievable throughput performance employing the proposed codebook is always superior to those of the differential codebooks employing M -PSK constellations and non-adaptive differential codebooks with the same amount of feedback information.

The long term evolution (LTE) standard for uplink transmission is based on single carrier frequency division multiple access (SC-FDMA) maintaining low peak-to-average power ratio (PAPR), which is very valuable for the practical handset design. Recently the usage of codebook-based precoding has been thoroughly discussed for the LTE-Advanced (LTE-A) uplink. Among the various precoding schemes, equal gain transmission (EGT) is proposed in this paper because it does not increase any PAPR. Especially, considering a nonlinear transmit power amplifier model in the uplink, EGT is superior to any other precoding schemes. Theoretical analysis of precoding schemes' PAPR is presented under a quasi-static flat fading channel, and link-level bit error rate (BER) is simulated to corroborate the anticipated results.

White LED technology, which is regarded as an environmentfriendly lighting, not only illuminates rooms but also makes a short range wireless communication. Recently, DMT techniques like OFDM are adopted for WLED communication. However as OFDM has an inherent high PAPR property, flickering light can be detected by human eyes. In this paper, the application of SC-FDMA (single-carrier frequency division multiplexing access) to WLED communication system is investigated. Because of low PAPR property, White LED communication system combined with SC-FDMA outperforms that combined with OFDM on BER performance under various consideration, moreover, the proposed system also protects LED device's lifetime and human's eye from over bright due to peak signal power. Computer simulations corroborate the analysis.

No abstract

No abstract

Dual-layer differential codebook using 8-PSK (phase shift keying) constellation as its codeword elements, is proposed for Long term evolution (LTE) and/or LTE-Advanced systems. Due to the temporal correlation of the adjacent channel matrices, the consecutive precoding matrices are likely to be similar. This approach quantize only the differential information of the channel instead of the whole channel subspace, which virtually increase the codebook size to realize more accurate quantization of the channel. Especially, the proposed codebook has the same properties of LTE release-8 codebook that is, constant modulus, complexity reduction, and nested property.The mobile station can be designed by using less expensive non-linear amplifier utilizing constant modulus property. Computer simulations show that the capacity of the proposed dual-layer codebook performs almost 1.2dB better than those of any other non-differential codebooks with the same amount of feedback information.