Delay analysis of social group multicast-aided content dissemination in cellular system

Based on the common interest of mobile users (MUs) in a social group, the dissemination of content across the social group is studied as a powerful supplement to conventional cellular communication with the goal of improving the delay performance of the content dissemination process. The content popularity is modelled by a Zipf distribution in order to characterize the MUs’ different interests in different contents. The Factor of Altruism (FA) terminology is introduced for quantifying the willingness of content owners to share their content. We model the dissemination process of a specific packet by a pure-birth based Markov chain and evaluate the statistical properties of both the network’s dissemination delay as well as of the individual user-delay. Compared to the conventional base station (BS)- aided multicast, our scheme is capable of reducing the average dissemination delay by about 56.5%. Moreover, in contrast to the BS-aided multicast, increasing the number of MUs in the target social group is capable of reducing the average individual userdelay by 44.1% relying on our scheme. Furthermore, our scheme is more suitable for disseminating a popular piece of content

Performance analysis of non-linear generalised pre-coding aided spatial modulation

Developed from the recently emerged generalized pre-coding aided spatial modulation (GPSM) concept, a novel non-linear GPSM scheme based on the powerful vector perturbation philosophy is proposed, where a particular subset of receive antennas is activated and the specific activation pattern itself conveys useful implicit information in addition to the conventional modulated and perturbed symbols. Explicitly, both the infinite and finite alphabet capacities are derived for the proposed non-linear GPSM scheme. The associated complexity, energy efficiency, and error probability are also investigated. Our numerical results show that, as the only known non-linear realization within the spatial modulation family, the proposed scheme constitutes an attractive solution to the flexible design of green transceivers, since it is capable of striking a compelling compromise amongst the key performance indicators of throughput, energy consumption, complexity, and performance. In particular, in the challenging full-rank scenario, conveying information through receive antenna indices exhibits a lower complexity, a higher energy efficiency, and a better error resilience than that of the conventional arrangement

Socially aware integrated centralized infrastructure and opportunistic networking: a powerful content dissemination catalyst

The classic centralized infrastructure (CI) exhibits low efficiency in disseminating the content of common interest across its requesters. In order to overcome the limitations of CI-based content dissemination, smart mobile devices are capable of activating direct opportunistic communications among mobile users, which returns in integrated cellular and opportunistic networks. During the content dissemination process, the social characteristics of multiple users, including their common interest in the content, their mobility patterns, their social ties, and their altruistic forwarding behaviors, should be carefully considered in order to design an efficient content dissemination scheme. We demonstrate that the integrated network-based content dissemination scheme outperforms its CI-based counterpart in terms of both content delivery ratio and its various energy and delay metrics. Furthermore, the opportunistic network is capable of offloading a large fraction of tele-traffic from the overloaded CI-based network

Performance of cognitive hybrid automatic repeat reQuest: stop-and-wait

Detecting spectrum holes and efficiently accessing them are the two basic functions that enable a cognitive radio (CR) to make use of the licensed spectrums of a primary radio (PR). In this paper, we consider a CR scheme, which opportunistically accesses a PR channel for communication between a pair of nodes based on the stop-and-wait hybrid automatic repeat request (SW-HARQ). Hence, it is referred to as the cognitive SW-HARQ (CSW-HARQ) arrangement. In our CSW-HARQ system, the PR channel is modelled as a two-state Markov chain having 'On' and 'Off' states. The CR may only access the PR channel in its 'Off' state. In this paper, we analyze both the throughput and delay performance of the CSW-HARQ system, for which a range of closed-form formulas are derived that are also validated by simulation results. Our performance results show that both the activities of PR users and the reliability of the CR channel have a substantial impact on the achievable performance of the CR system

Compressed impairment sensing-assisted and interleaved-double-FFT-aided modulation improves broadband power line communications subjected to asynchronous impulsive noise

In power line communications (PLCs), the multipath-induced dispersion and the impulsive noise are the two fundamental impediments in the way of high-integrity communications. The conventional orthogonal frequency-division multiplexing (OFDM) system is capable of mitigating the multipath effects in PLCs, but it fails to suppress the impulsive noise effects. Therefore, in order to mitigate both the multipath effects and the impulsive effects in PLCs, in this paper, a compressed impairment sensing (CIS)-assisted and interleaved-double-FFT (IDFFT) aided system is proposed for indoor broadband PLC. Similarly to classic OFDM, data symbols are transmitted in the time-domain, while the equalization process is employed in the frequency-domain in order to achieve the maximum attainable multipath diversity gain. Additionally, a specifically designed interleaver is employed in the frequency-domain in order to mitigate the impulsive noise effects, which relies on the principles of compressive sensing (CS). Specifically, by taking advantage of the interleaving process, the impairment impulsive samples can be estimated by exploiting the principle of CS and then cancelled. In order to improve the estimation performance of CS, we propose a beneficial pilot design complemented by a pilot insertion scheme. Finally, a CIS-assisted detector is proposed for the IDFFT system advocated. Our simulation results show that the proposed CIS-assisted IDFFT system is capable of achieving a significantly improved performance compared to conventional OFDM. Furthermore, the tradeoffs to be struck in the design of the CIS-assisted IDFFT system are also studied

Spatially modulated code-division multiple-access for high-connectivity multiple-access

In order to take the advantages of spatial modulation (SM) and support the multiple access (MA) communications requiring high-connectivity, we integrate the SM with DS-CDMA to propose a SM/DS-CDMA scheme, which is in favor of attaining both antenna diversity and frequency diversity. Associated with the SM/DS-CDMA scheme, a range of linear and nonlinear multiuser detectors (MUDs) are proposed and studied. Specifically, for linear MUDs, both minimum mean-square error aided joint spatial demodulation (MMSE-JSD) and MMSE-aided separate spatial demodulation (MMSE-SSD) are introduced. For nonlinear MUDs, we first present the joint maximum-likelihood MUD (JML-MUD) for demonstrating the potential of SM/DS-CDMA systems. Then, the MMSE-relied iterative interference cancellation (MMSE-IIC) is suggested, and associated with which two types of low-complexity high-efficiency reliability measurement schemes are proposed. In this paper, we mathematically analyze both the single-user average bit error rate (ABER) of the SM/DS-CDMA systems employing joint spatial demodulation (JSD), and the approximate ABER of the SM/DS-CDMA systems employing the MMSE-JSD. We investigate and compare the ABER performance of the SM/DS-CDMA systems with various detection schemes, and also with some legacy schemes. Our studies and performance results show that the SM/DS-CDMA systems in conjunction with appropriate MUD schemes are capable of providing a desirable trade-off among the number of users supportable, implementation complexity and the ABER performance

Equalisation and performance of diffusive molecular communication systems with binary molecular-shift keying modulation

This study investigates the equalisation techniques for the diffusive molecular communication (DMC) systems with binary molecular-shift keying (BMoSK) modulation, referred to as the BMoSK-DMC systems, in order to mitigate the effect of inter-symbol interference (ISI). The authors first show that in terms of receiving equalisation, a BMoSK-DMC system is in fact equivalent to a conventional binary phase-shift keying modulated radio communication system encountering ISI. Hence, a wealth of equalisation techniques developed with the conventional radio communication systems may be introduced for equalisation of BMoSK-DMC signals. However, considering the limited capability of molecular transceivers on computation and storage, in this study, the authors investigate only the linear equalisers (LEQ) in the principles of matched-filtering, zero-forcing (ZF) and minimum mean-square error (MMSE). They characterise the effects of the different aspects related to DMC signalling and propagation on the achievable performance of the BMoSK-DMC systems with these LEQ. Their studies and performance results demonstrate that both the ZF- and MMSE-LEQ are capable of efficiently suppressing the ISI and attaining promising performance, while still have low-complexity to facilitate implementation

Database for the VTC2016-Nanjing accepted conference paper entitled with "LDPC-Coded Index-Modulation Aided OFDM for In-vehicle Power Line Communications"

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Error performance analysis of diffusive molecular communication systems with on-off keying modulation

In this paper, we analyze the bit error rate (BER) of the diffusive molecular communication (DMC) systems employing on-off keying (OOK) modulation. We also analyze the BER of the OOK-modulated DMC systems with inter-symbol interference cancellation (ISIC). Our main motivation is to introduce alternative tools for analyzing and efficiently computing the BER of the DMC systems without or with ISIC. Specifically, for the OOK-modulated DMC systems without ISIC, we first derive an exact BER expression based on the Poisson modeling of DMC systems. Then, the Gaussian- and Gamma-approximation approaches are introduced to approximate the discrete Poisson distribution, and based on the approximation approaches, the corresponding BER expressions are derived. Furthermore, in order to reduce the computation complexity imposed by long ISI, we propose the Monte-Carlo, simplified Poisson, simplified Gaussian and the simplified Gamma approaches for BER computation. In the context of the OOK-modulated DMC systems with ISIC, we consider both the Poisson and Gaussian-approximation approaches for BER analysis. Again, exact and approximate BER expressions are derived under the Poisson, Gaussian-approximation, simplified Poisson and simplified Gaussian approaches. Finally, the considered approaches are compared and validated by a range of performance results obtained from evaluation of the derived expressions or by simulations. Our studies show that the alternative approaches are in generaleffective for providing near-accurate BER estimation