Transmission Rate Performance Research Articles

A multi-layer VLC imaging system based on space-time trace-orthogonal coding

In visible light communication (VLC) imaging systems, different properties of data are usually demanded for transmission with different priorities in terms of reliability and/or validity. For this consideration, a novel transmission scheme called space-time trace-orthogonal coding (STTOC) for VLC is proposed in this paper by taking full advantage of the characteristics of time-domain transmission and space-domain orthogonality. Then, several constellation designs for different priority strategies subject to the total power constraint are presented. One significant advantage of this novel scheme is that the inter-layer interference (ILI) can be eliminated completely and the computation complexity of maximum likelihood (ML) detection is linear. Computer simulations verify the correctness of our theoretical analysis, and demonstrate that both transmission rate and error performance of the proposed scheme greatly outperform the conventional multi-layer transmission system.

Quality of Service Analysis of Ethernet Network Based on Packet Size

Ethernet network, standardized by IEEE 802.3, is vastly installed in Local Area Network (LAN) for cheaper cost and reliability. With the emergence of cost effective and enhanced user experience needs, the Quality of Service (QoS) of the underlying Ethernet network has become a major issue. A network must provide predictable, reliable and guaranteed services. The required QoS on the network is achieved through managing the end-to-end delay, throughput, jitter, transmission rate and many other network performance parameters. The paper investigates QoS parameters based on packet size to analyze the network performance. Segmentation in packet size larger than 1500 bytes, Maximum Transmission Unit (MTU) of Ethernet, is used to divide the large data into small packets. A simulation process under Riverbed modeler 17.5 initiates several scenarios of the Ethernet network to depict the QoS metrics in the Ethernet topology. For analyzing the result from the simulation process, varying sized packets are considered. Hence, the network performance results in distinct throughput, end-to-end delay, packet loss ratio, bit error rate etc. for varying packet sizes.

Uplink User-Assisted Relaying in Cellular Networks

We use stochastic geometry to analyze the performance of a partial decode-and-forward (PDF) relaying scheme applied in a user-assisted relaying setting, where an active user relays data through another idle user in uplink cellular communication. We present the geometric model of a network deploying user-assisted relaying and propose two geometric cooperation policies for fast and slow fading channels. We analytically derive the cooperation probability for both policies. This cooperation probability is further used in the analytical derivation of the moments of intercell interference power caused by system-wide deployment of this user-assisted PDF relaying. We then model the intercell interference power statistics using the Gamma distribution by matching the first two moments analytically derived. This cooperation and interference analysis provides the theoretical basis for quantitatively evaluating the performance impact of user-assisted relaying in cellular networks. We then numerically evaluate the average transmission rate performance and show that user-assisted relaying can significantly improve per-user transmission rate despite of increased intercell interference. This transmission rate gain is significant for active users near the cell edge and further increases with higher idle user density, supporting user-assisted relaying as a viable solution to crowded population areas.

Iterative multiuser detection for LDPC MIMO SC‐FDMA communication systems

AbstractIn order to provide high quality services, current communication systems require high‐data transmission rate and good error performance. Because single‐carrier frequency division multiple access (SC‐FDMA) is with the desirable characteristics of orthogonal frequency division multiple access and the low peak‐to‐average power ratio of single‐carrier transmission schemes, it has been adopted as the uplink transmission scheme in 3GPP long‐term evolution to approach the demand for data transmission rates and error performance. By combining multiple‐input multiple‐output (MIMO) techniques with the SC‐FDMA modulation scheme, MIMO SC‐FDMA systems can achieve high data rates over broadband wireless channels. In this paper, we propose the iterative multiuser detection scheme for the low‐density parity‐check‐coded MIMO SC‐FDMA communication systems. On the basis of the property of space‐frequency block coding, we develop the frequency domain minimum mean‐squared error and zero‐forcing equalisers with multiuser interference cancellation technique on each subcarrier to recover the transmitted symbols. Some simulation examples for uplink scenario are given to demonstrate the effectiveness of the proposed schemes. Copyright © 2014 John Wiley & Sons, Ltd.

Novel Modulation Techniques using Isomers as Messenger Molecules for Nano Communication Networks via Diffusion

In this paper, we propose three novel modulation techniques, i.e., concentration-based, molecular-type-based, and molecular-ratio-based, using isomers as messenger molecules for nano communication networks via diffusion. To evaluate achievable rate performance, we compare the proposed tech- niques with conventional insulin based concepts under practical scenarios. Analytical and numerical results confirm that the proposed modulation techniques using isomers achieve higher data transmission rate performance (max 7.5 dB signal-to-noise ratio gain) than the insulin based concepts. We also investigate the tradeoff between messenger sizes and modulation orders and provide guidelines for selecting from among several possible candidates.

A High-Speed Power-Line Communication System with Band-Limited OQAM Based Multi-Carrier Transmission

As a method to realize a high-speed communication in the home network, the power-line communication (PLC) technique is known. A problem of PLC is that leakage radiation interferes with existing systems. When OFDM is used in a PLC system, the leakage radiation is not sufficiently reduced, even if the subcarriers corresponding to the frequency-band of the existing system are never used, because the signal is not strictly band-limited. To solve this problem, each subcarrier must be band-limited. In this paper, we apply the OQAM based multi-carrier transmission (OQAM-MCT) to a high-speed PLC system, where each subcarrier is individually band-limited. We also propose a pilot-symbol sequence suitable for frequency offset estimation, symbol-timing detection and channel estimation in the OQAM-MCT system. In this method, the pilot signal-sequence consists of a repeated series of the same data symbol. With this method, the pilot sequence approximately becomes equivalent to OFDM sequence and therefore existing pilot-assisted methods for OFDM are also applicable to OQAM-MCT system. Computer simulation results show that the OQAM-MCT system achieves both good transmission rate performance and low out-of-band radiation in PLC channels. It is also shown that the proposed pilot-sequence improves frequency offset estimation, symbol-timing detection and channel estimation performance as compared with the case of using pseudo-noise sequence.

Iterative Decoding Algorithm in the Adaptive Modulation and Coding System with MIMO Schemes

In this paper, we propose and analyze the adaptive modulation system with optimal Turbo Coded V-BLAST (Vertical-Bell-lab Layered Space-Time) technique that adopts extrinsic information from a MAP (Maximum A Posteriori) decoder with iterative decoding as a priori probability in two decoding procedures of V-BLAST scheme; the ordering and the slicing. Also, we consider the AMC (Adaptive Modulation and Coding) using the conventional Turbo Coded V-BLAST technique that simply combines the V-BLAST scheme with the turbo coding scheme. And we compare the proposed iterative decoding algorithm to a conventional V-BLAST decoding algorithm and a ML (Maximum Likelihood) decoding algorithm. In this analysis, the MIMO (Multiple Input Multiple Output) and the STD (Selection Transmit Diversity) schemes are assumed to be parts of the system for performance improvement. Results indicate that the proposed systems achieve better throughput performance than the conventional systems over the whole SNR (Signal to Noise Ratio) range. In terms of transmission rate performance, the suggested system is close in proximity to the conventional system using the ML decoding algorithm. In addition, the simulation result shows that the maximum throughput improvement in each MIMO scheme is respectively about 350kbps, 460kbps, and 740kbps. It is suggested that the effect of the proposed iterative decoding algorithm accordingly gets higher as the number of system antenna increases.

Application of Adaptive QAM Modulation and Diversity Scheme for 30 GHz Cellular Communications under the Impact of Rain Attention in Indonesia

In millimeter-wave wireless cellular systems like Local Multipoint Distribution Services (LMDS) rain attenuation is an essential factor of performance degradation. It can cause signal outages and poor quality of signal reception. To mitigate the problem, a combination of diversity and adaptive modulation is proposed. To investigate the impact of the use of these techniques, a simulation is performed for a 30 GHz cellular system to obtain SNR (signalto- noise ratio), diversity gain, modulation level and BER (bit error rate). Analysis of the implementation of the combined techniques is accomplished by taking into account such factors as length of links and the combining method Simulation results show that diversity can improve the overall system SNR. Diversity gain of up to 15 dB can be achieved on two 4-km converging links at 0.01% outage probability when maximal-ratio combining (MRC) is used. For systems with luxurious link design for which the clearsky SNR is more than 30 dB, as considered in this paper, diversity and adaptive modulation do not significantly contribute to improvement of achievable transmission rate and BER performance. However, for systems with lower values of clear-sky SNR, use of both techniques will be more worthwhil.

Constant Amplitude Signaling for Parallel Combinatory Spread Spectrum Systems

In this paper, a parallel combinatory spread spectrum (PC/SS) system using a constant amplitude signaling scheme is proposed. The amplitude of the transmitted signal from multicode transmission systems such as PC/SS systems have a large dynamic range which requires that amplifiers have a wide linearity in the transmitter. From a view point of power efficiency, however, it is reasonable to use non-linear amplifiers rather than linear ones. In that case, the bit error rate performance must degrade because of non-linear distortion. The proposed system can avoid influence of the non-linear amplifiers by making the transmitted signal have a constant amplitude. The bit error rate performance and the data transmission rate performance are investigated. They prove that the proposed system is an attractive candidate among the constant amplitude signaling systems.