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Due to the open access nature of wireless communication environment, physical layer security has brought increasingly high attention in recent years, attempting to protect the confidential communication away from eavesdroppers. In contrast to the current secrecy designs, which generally exploit the spatial Degree-of-Freedom (DoF) (e.g. MIMO and cooperative relay approaches) or the temporal DoF (e...
This paper presents a recursive oblique projector using the Gram-Schmidt process. The recursive construction of oblique projectors allows a receiver to prevail interference and noise environment in direct-sequence code-division multiple-access (DS/CDMA) system. When the number of the interfering users in the system increases or decreases, the oblique projector is recursively updated by the proposed...
Machine Type Communication (MTC) is a key component of future 5G networks, and its realization is now possible due to the advances in technology and the market drivers. Several challenges however exist which hinder the realization of MTC, among which signaling overhead is considered the prominent challenge, particularly due to the massive number of devices in MTC networks. In this work, we consider...
This study concerns about Beamforming techniques in a Multi-User Indoor environment at mm-Wave E-band. Directional mm-Wave measurement data are used as reliable radio channel reference for the study and, furthermore, are checked against advanced Ray Tracing simulations. The main goal is to assess the quality of Spatial Division Multiple Access using three different Beamforming schemes in order to...
We define a multiaccess communication scheme that effectively eliminates interference and resolves collisions in many-to-one and many-to-many communication scenarios. Each transmitter is uniquely identified by a coding vector. Using these vectors, all signals issued from a specific transmitter will be aligned along a unique dimension at all receivers hearing this transmission. This dimension is characteristic...
In this work, we present buffer-aided physical-layer network coding (PLNC) schemes and develop novel PLNC algorithms for cooperative direct-sequence code-division multiple access systems. In the proposed buffer-aided PLNC schemes, we employ a relay pair selection algorithm to select the relay pair and the packets in the buffer entries with the best performance and the associated link combinations...
Authors investigate telecommunication system with a multi-position phase-shifted signal. The calculations of the system's noise immunity with different number of signal positions is performed. An estimation of the system's noise immunity is evaluated against the influence of broadband interference with increasing of the signal's positions number. It is shown that when using a multi-position phase-shift...
In this paper the potential of intrasystem interference in the marine navigation system neutralization using frequency division multiple access is shown. The results of the simulation are presented.
This paper discusses the contemporary problem of providing multiple-access (MAC) to a massive number of uncoordinated users. First, we define a random-access code for Ka-user Gaussian MAC to be a collection of norm-constrained vectors such that the noisy sum of any Ka of them can be decoded with a given (suitably defined) probability of error. An achievability bound for such codes is proposed and...
An undesirable side-effect of network densification is a reduced quality of service due to increased contention. One interesting solution to address this issue is full-duplex medium access control (MAC) with collision detection. By detecting collisions early on, a considerable amount of energy can be saved in dense networks. However, when traffic demand and, as a result, the collision rate decrease,...
Interference is one of the factors influence the number of active sensors of the CDMA Wireless Sensor Network as it affects Eb/I0 on the received signal. The higher the interference, the smaller the capacity is. One of the methods to minimize the interference is cluster formation in the CDMA Wireless Sensor Network. Using cluster, the interference can be minimized because transmission power to send...
With the vision of deployment of massive Internet-of-Things (IoTs) in 5G network, existing 4G network and protocols are inefficient to handle sporadic IoT traffic with requirements of low-latency, low control overhead and low power. To suffice these requirements, we propose a design of a PHY/MAC layer using Software Defined Radios (SDRs) that is backward compatible with existing OFDM based LTE protocols...
In this paper, the outage performance of nonorthogonal multiple access (NOMA) is investigated in a downlink space division multiple access (SDMA) network with a multi-antenna base station and randomly deployed users. The NOMA technology is concurrently exploited with SDMA to further improve spectral efficiency. With limited channel state information (CSI) feedback taken into account, an analytical...
Visible light communication is an emerging field in indoor wireless connection, and it is a candidate technique to provide high-speed data transmission. In this paper, we propose a joint optimal waveform design system to support multiple users. In this system, transmitted waveforms and minimum mean squared error filters are jointly optimized to minimize the inter-symbol interference and multiple access...
The macro- and micro-diversity schemes for the W-CDMA base stations deployed with smart antennae are investigated and their performances in terms of the improvement in the received bit energy to interference PSD ratio are evaluated, where both the adaptive and fixed beam schemes are considered for smart antenna systems. The macro-diversity scheme is employed to compensate the decrease of antenna gain...
Methods of modern GNNS organization, their frequency bandwidth and signals generation were described. Nowadays bandwidth for every field of concern is strongly limited. Popularity of radionavigation leads to overlapping spectrum. Modern GNSS are using signals with CDMA to minimize interference. The signals non-orthogonality interference are named multiple-access interference. The multiple-access interference...
To provide support for both data and voice is essential requirement of present mobile networks both LTE and UMTS networks. The proposed scheme in this paper differentiates assignment of requested calls on: speed, direction of motion and type of requested call. It also checks the used capacity threshold of LTE and UMTS before assignment. Different communication interfaces are used in hybrid mobile...
By offloading mobile traffic for macrocells, small cells can help to alleviate the pressure on conventional cellular networks from explosive data growth. On the other hand, the severe spectrum scarcity problem has prompted the research on spectrum sharing recently. In this paper, a spectrum sharing system of OFDMA small cells overlaying CDMA networks is considered, in which each OFDMA user in the...
The research is devoted to the reduction of multiple access interference (MAI) in chaos-based asynchronous direct sequence code division multiple access (DS-CDMA) communication systems by use of spreading sequences which are selected from a large set of generated chaotic sequences. For the generation of binary chaotic spreading sequences different 1-dimensional maps are examined. As selection criteria...
In this paper, we present the beamforming technologies used for increasing the system capacity at unlicensed band. We investigate the international research trend and the key technology of some companies, such as Wavion, GoNet, and Ruckus Inc. We also introduce the Binary CDMA technologies good at PAPR characteristics. Finally, we analysis the performance of receive beamforming using Compact MIMO...
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