A New Solution for Simple Cooperative Relaying

In this paper we present a new simple cooperative relaying scheme. The proposed scheme is compared with simple cooperative schemes with virtual orthogonal space time block coding (OSTBC) and quasi orthogonal space time block coding (QOSTBC). Every of these three schemes includes one base station with two antennas, two relay stations each with a single antenna and one mobile station with a single antenna. The aim of the proposed scheme is to preserve, as much as it is possible bit error rate (BER) performance of the cooperative scheme with virtual OSTBC, but with increased code rate. It is shown that the presented scheme obviously outperforms simple cooperative scheme with virtual QOSTBC, while in comparison with simple cooperative scheme with virtual OSTBC has very similar BER performance and increased code rate.     

A New Full Rate Relaying Method for 4G OFDM Systems

In this paper, we introduce a new transmit architecture that employs a 2-Dimensional Fourier Transform and a 2-Dimensional Cyclic Prefix (2D-CP) at the base station. In addition, the proposed scheme incorporates relay nodes that forward the received signals with one OFDM symbol delay. The new method introduces artificial frequency, time and spatial diversity, and unlike previously proposed relaying communication systems, the proposed scheme requires only a single transmission phase. Extensive system simulation studies have shown impressive system throughput gain compared to a single hop and conventional 2-hop systems.     

Probability Analysis of Capacity Gain by Cooperative Relaying Over Single-Hop OSTBC Transmission in Low SNR Regime

In this paper, we investigate the capacity gain obtained by putting a multiple-antenna relay in an original single-hop multiple-input multiple-output system using an orthogonal space-time block code over uncorrelated Rayleigh fading channels. As relaying techniques, we consider decode-and-forward relaying as well as decouple-and-forward relaying in which no decoding is performed at the relay. Focusing on the low signal-to-noise ratio regime, closed-form expressions of the probability of the capacity gain are provided for the respective relaying schemes. The probability results in an explicit function of an average power ratio of the per-hop channel in dual-hop relaying to the single-hop channel. Numerical examples show the impact of the power ratio, the relaying strategy, the number of antennas and the relay location on the capacity gain, respectively.     

Cooperative Relaying Scheme for Orthogonal Frequency and Code Division Multiple Access Uplink System

Orthogonal frequency and code division multiplexing (OFCDM) which can be extended orthogonal frequency and code division multiple access (OFCDMA) has a good performance, because it can mitigate multi path interference while maintaining high data rate. Furthermore, cooperative OFCDM relaying system provides these advantages, and this system can effectively use the limited resource with respect to data rate and each terminal’s energy efficiency. Therefore we proposed cooperative OFCDMA relaying uplink system because of the user’s requirement of the high data rate at uplink. However, a throughput performance decreases when this system employs many relays in case of each relay allocated code channel to separate each relay’s signal. Therefore, in this paper, we present that the proposed system combines cyclic delay diversity due to complement throughput performance problem. DF (Decode-and-Forward) is assumed in this paper. It is considered that the users which want to send data to BS only decode the data from other users. In addition to that, we propose the adaptive cooperative communication for the OFCDMA uplink system. The proposed adaptive system can easily select the cooperative relay.     

采用CS3/CS4编码改善GPRS传输速率

本文对CS3/CS4编码原理进行介绍,通过理论分析与实际测试结果,得到CS3/CS4对GPRS数据业务传输速率的提高程度,对无线信道的要求以及与现网话音业务的相互影响.最后给出CS3/CS4的应用策略.     

Full-Duplex Relaying Schemes for Cooperative NOMA Networks with SWIPT

Wireless Personal Communications - Existing security approaches for safeguarding data exchange among the sensor nodes are investigated in presence of apriori information of an adversary in...     

Timing Synchronization for Cooperative Communications with Detect and Forward Relaying

A non-data-aided near maximum likelihood (NDA-NML) symbol timing estimator is presented, which is applied to a cooperative communication system with a source, relay and destination. A Cramer rao bound (CRB) for the estimator for asymptotically low signal-to-noise (SNR) ratio case is derived. The timing complexity of the NDA-NML estimator is derived and compared with the correlation based data-aided maximum likelihood (DA-ML) estimator. It is demonstrated that the complexity of the NDA-NML estimator is much less than that of correlation based DA-ML estimator. The bit-error-rate (BER) performance of this system operating in a detect-and-forward (DAF) mode is studied where the channel state information (CSI) is available at the receiver and the symbol timings are estimated independently for each channel. SNR combining (SNRC) and equal ratio combining (ERC) methods are considered. It is found that timing estimation error has a significant effect on BER performance. It is also found that for large timing error the benefit of cooperative diversity could vanish. It is demonstrated that significant gains can be made with both combining methods with cooperation and timing estimation, where the gains are the same for both estimators.     

Rate 3/4 Convolutional Coding of 16-PSK: Code Design and Performance Study

Convolutional coding coupled with 16-PSK modulation is investigated for bandwidth efficient transmission. Rate 3/4, small memory codes are found which are optimized in the free-distance sense on the Gaussian channel. These codes provide up to 4.8 dB of coding gain with 32 states over uncoded 8-PSK, a scheme having the same spectral efficiency as the codes described. The performance is compared with earlier findings of Ungerboeck and some recent results onR = 2/3coded 8-PSK. In addition, we present results of a channel transmission study to assess the performance of the four-state code on the band-limited nonlinear channel, and find that performance of the coded scheme degrades comparably with uncoded 8-PSK, i.e., coding gain is roughly preserved.     

Cooperative Subcarrier Allocation for an OFDM Relaying System with Grouped Users

In this article, the problem of downlink subcarrier allocation in a cooperative wireless multiuser OFDM system is investigated. We consider a single-cell where all the users are paired in cooperative groups. The mobile users in each group amplify and forward their partner’s data stream using a time division protocol. Based on the capacity contribution from the relaying terminal, a new parameter called cooperation coefficient is introduced as a function of the relaying subchannel. This parameter is used to modify the objective parameter of the subcarrier allocation procedure. Fairness-oriented and throughput-oriented algorithms are selected from the literature to test the proposed technique. Both algorithms are modified to employ the mean of cooperation coefficient in the objective parameter of the subcarrier allocation procedure and shown to have a better total throughput without any sacrifice. Using the mean of cooperation coefficient eliminates the need for the feedback of the relaying channel to the base station. It is shown that by using the mean value of the cooperation coefficient, instead of its instantaneous value, throughput of the system would still improve compared to the non-cooperative case. Using the mean of cooperation coefficient leads to an implementable cooperative subcarrier allocation algorithm.     

On the SEP of Cooperative Diversity with Opportunistic Relaying

We analyze the exact symbol error probability (SEP) of cooperative diversity with opportunistic amplify-and-forward (AF) relaying. The benefit of this opportunism to the SEP is assessed by comparing with maximal ratio combining of orthogonal multiple AF relay transmissions.     

Adaptive Path Selection Scheme with Combining for Multiple Relaying Cooperative Communications Networks

In future communications, cooperative communications with relay networks will be one of the most effective schemes to enlarge the coverage area and to boost the data rate. In the recent research results, the path selection, power allocation, and relay protocols on relay networks are the most important factors to improve the system performance. However, the channel quality of the direct transmission path and the relaying path has an influential effect on the performance of relay networks. Therefore, in this paper, we propose a best relaying path selection (BRPS) scheme to obtain the path diversity to improve the system capacity and data rate for cooperative networks (CNs). Simulation results show that the more the relay nodes are selected, the lower the bit error rate (BER) is. The proposed BRPS scheme obtains a high concession between both BER and system capacity for CNs.     

Capacity of Multiuser Diversity with Cooperative Relaying in Wireless Networks

This letter provides an analysis of the interaction between cooperative diversity and multiuser diversity in downlink channels. Through an approximation of the signal-to-noise ratio (SNR) distribution of each cooperative link using gamma distribution, we can derive an analytic expression for the average throughput of a single-cell wireless system with multiple cooperative diversity links combined with a fair-access scheduler. The proposed analytic approach is verified through comparisons with simulated results and shows that cooperative diversity has a detrimental impact on multiuser diversity.     

SR-DCSK Cooperative Communication System with Code Index Modulation:A New Design for 6G New Radios

This paper proposes a high-throughput short reference differential chaos shift keying cooperative communication system with the aid of code index modulation,referred to as CIM-SR-DCSK-CC system.In the proposed CIM-SR-DCSK-CC system,the source transmits information bits to both the relay and destination in the first time slot,while the relay not only forwards the source information bits but also sends new information bits to the destination in the second time slot.To be specific,the relay employs...     

TD-SCDMA系统中Turbo编码速率匹配在ZSP500上的快速实现

速率匹配是基带信号处理的重要组成部分。文中在深入研究3GPP协议中Turbo编码速率匹配算法的基础上，提出了一种可用DSP实现的快速实现方案，该方案简化了实现过程，有效地减小了Turbo编码速率匹配的处理延时。     

基于OFDM-IM的认知无线电协作中继性能分析

该文针对协作认知无线电网络场景,提出一种基于索引调制正交频分复用(OFDM-IM)的新型协作中继设计方法。该方法将OFDM-IM技术应用于从用户发送端,将从用户的传输空间划分为信号空间和索引空间。从用户在其信号空间上转发主用户的信息,同时在索引空间传输从用户信息。通过这种方式,主、从用户之间不存在相互干扰。针对此模型,该文分析了主、从用户的误码率,理论推导了相关表达式,并讨论了从用户的位置对主、从用户性能的影响。仿真结果表明,该文所提设计方法能够同时提升主、从用户的误码率性能,且均优于传统的基于OFDM的协作中继方式。     

A New 1/4 Rate Modulation Techniques for Enhanced-xVSB System

In this paper, we describe a new 1/4 rate robust modulation techniques for Enhanced-xVSB system which is fully backward compatible with ATSC 8-VSB standard. 1/4 rate mode Enhanced-xVSB system provides broadcasters with a wide choice of trade-offs of data rate vs amount of robustness of enhanced data for pedestrian/mobile services. Lab test results of proposed Enhanced-xVSB 1/4 rate mode robust stream is a significantly improved multipath as well as AWGN reception performance for Enhanced-xVSB receiver. We suggest an Enhanced-xVSB terrestrial broadcasting system for ATSC HDTV and pedestrian/portable TV simultaneous broadcasting service providing     

Secrecy Rate of Two-Hop AF Relaying Networks with an Untrusted Relay

Two cooperative communication protocols, two-way and one-way half-duplex relayings, are investigated and then compared in the amplify-and-forward (AF) mode. The relay is assumed to play the roles of eavesdropper and relay (i.e., an untrusted relay). With a fair power constraint at each node, the secrecy rate of the one-way relaying protocol is proved to be zero strictly. For the two-way relaying protocol, the signal-to-noise ratio (SNR) threshold is derived, above which the secrecy rate is non-zero. Defining a parameter, namely mistrust level, and non-zero secrecy rate can be achieved for the one-way relaying protocol in certain range of the mistrust level at high SNR. With a fair total power constraint, no matter how unreliable the relay is, the two-way AF half-duplex relaying protocol is proved to be a better choice under high SNR.     

New Two-dimensional Modified Quadratic Congruence Code/Optical Orthogonal Code for OCDMA

A new family of two-dimensional optical orthogonal code（2-DOOC）, namely, modified quadratic congruence code（MQCC ）/optical orthogonal code（OOC） is proposed who employs MQCC and OOC as wavelength hopping and time-spreading patterns, respectively. Through analyzing the performance of MQCC/ OOC, we can see that the correlation properties of the MQCC/OOC are still ideal. Simultaneously, our analysis shows that the proposed new code families can get more cardinalities than other codes and can improve the bit error rate（BER） of optical code division multiple access（OCDMA） effectively.