Extension and practical evaluation of the spatial modulation concept

The spatial modulation (SM) concept combines, in a novel fashion, digital modulation and multiple antenna transmission for low complexity and spectrally efficient data transmission. The idea considers the transmit antenna array as a spatial constellation diagram with the transmit antennas as the constellation points. To this extent, SM maps a sequence of bits onto a signal constellation point and onto a spatial constellation point. The information is conveyed by detecting the transmitting antenna (the spatial constellation point) in addition to the signal constellation point. In this manner, inter-channel interference is avoided entirely since transmission is restricted to a single antenna at any transmission instance. However, encoding binary information in the spatial domain means that the number of transmit antennas must be a power of two. To address this constraint, fractional bit encoded spatial modulation (FBE—SM) is proposed. FBE–SMuses the theory of modulus conversion to facilitate fractional bit rates over time. In particular, it allows each transmitter to use an arbitrary number of transmit antennas. Furthermore, the application of SM in a multi-user, interference limited scenario has never been considered. To this extent, the average bit error rate (ABER) of SM is characterised in the interference limited scenario. The ABER performance is first analysed for the interference-unaware detector. An interference-aware detector is then proposed and compared with the cost and complexity equivalent detector for a single–input multiple–output (SIMO) system. The application of SM with an interference-aware detector results in coding gains for the system. Another area of interest involves using SM for relaying systems. The aptitude of SM to replace or supplement traditional relaying networks is analysed and its performance is compared with present solutions. The application of SM to a fixed relaying system, termed dual-hop spatial modulation (Dh-SM), is shown to have an advantage in terms of the source to destination ABER when compared to the classical decode and forward (DF) relaying scheme. In addition, the application of SM to a relaying system employing distributed relaying nodes is considered and its performance relative to Dh-SM is presented. While significant theoretical work has been done in analysing the performance of SM, the implementation of SM in a practical system has never been shown. In this thesis, the performance evaluation of SM in a practical testbed scenario is presented for the first time. To this extent, the empirical results validate the theoretical work presented in the literature

Maximising the system spectral efficiency in a decentralised 2-link wireless network

<p>Abstract</p> <p>This paper analyses the system spectral efficiency of a 2-link wireless network. The analysis reveals that there exist three operating points that possibly maximise the system spectral efficiency: either both links transmit with maximum power simultaneously or one single link transmits with maximum power while the other is silent. The impact of the chosen multiple access scheme on the system spectral efficiency is also studied: simultaneous transmission or sequential access where the two links share the medium by dedicated time/frequency slots without causing interference. An exhaustive numerical search over a wide range of channel realisations quantifies the gains in system spectral efficiency when choosing either the optimal, single, simultaneous, or sequential medium access. Furthermore, issues regarding the power efficiency are addressed. Finally, the restriction to a 2-link network is relaxed by introducing background interferers, reflecting a multiple link scenario with one dominant interferer. Simulation results indicate that increasing background interference reduces the advantage of sequential over simultaneous transmission.</p

Multiple access spatial modulation

International audienc

Types of geochemical associations in the Borov Dol - Shopur area interpretation of the data of primary and secondary haloes

The paper presents statistical calculations of the results of geochemical investigations of the primary and secondary dispersion haloes carried out on an area of some 40 km^2 in the Borov Dol - Shopur region (the Buchim ore district). Sampling was carried out on 500 x 200 spacing by research workers from IMGRE Moscow and the Buchim mine. The results obtained were first interpreted by the Geoscan method and the cluster analysis method (discussed in this paper), as well as the factor analysis of Kaiser method. Based on complex statistical calculations, correlation dependencies and classification of individual elements according to variogramas, factor distributions and dendograms, the types and geochemical associations distinguished are grouped us tollows: 1. Based on cluster analysis the following were distinguished: a) according to primary dispersion haloes (Pb, Zn, Sn). [(Ga, Ag) Vb]. (Ni, Co, Cr), [(Ti, Zr, Y) Nb]; b) according to secondary dispersion haloes [(Ni, Cr, Co) Mn]; [(Ti, V) Sc]; [(Vb, Nb) Ag]; (W, Ga); (Cu, Y) Mo; (Pb, Zn, Sn); 2. Based on data of factor analysis the following were distinguished: a) according to primary haloes [(Zr, Y. B, Ti) Nb]; (Sr); (Pb, Zn, Sn); (Ga, Ag, Vb); (B, Mn, Ni) Co, Cr b) according to secondary haloes: [(Ni, Cr. Co) Mn]; [(Vb, W, Nb) Ag, Ga)J; [(Ti, V) Sc)]; (Pb, Zn, Sn); (Cu, Y, Mo). Particular mention should be made of the (Pb, Zn, Sn) geochemical association which is clearly defined in both groups as well as (Cu, Y, Mo) as n characteristic association for the secondary dispersion haloes

2-User Multiple Access Spatial Modulation

International audienceSpatial modulation (SM) is a recently proposed approach to multiple-input-multiple-output (MIMO) systems which entirely avoids inter-channel interference (ICI) and requires no synchronisation between the transmit antennas, while achieving a spatial multiplexing gain. SM allows the system designer to freely trade off the number of transmit antennas with the signal constellation. Additionally, the number of transmit antennas is independent from the number of receive antennas which is an advantage over other multiplexing MIMO schemes. Most contributions thus far, however, have only addressed SM aspects for a point-to-point communication systems, i.e. the single-user scenario. In this work we seek to characterise the behaviour of SM in the interference limited scenario. The proposed maximumlikelihood (ML) detector can successfully decode incoming data from multiple sources in an interference limited scenario and does not suffer from the near-far problem

Terabit indoor laser-based wireless communications : LiFi 2.0 for 6G

This paper provides a summary of available technologies required for implementing indoor laser-based wireless networks capable of achieving aggregate data-rates of terabits per second as widely accepted as a sixth generation (6G) key performance indicator. The main focus of this paper is on the technologies supporting the near infrared region of the optical spectrum. The main challenges in the design of the transmitter and receiver systems and communication/networking schemes are identified and new insights are provided. This paper also covers the previous and recent standards as well as industrial applications for optical wireless communications (OWC) and LiFi

Ore Loses and Dilution of the Ore Vein No. 4 in the Zletovo Mine, Republic of Macedonia

Zletovo mines have a tradition of exploration and exploitation of vein lead-zinc ores for almost a century. Ore losses and dilutions have always been imperative in production since traditional old methods of mining and low-productivity mineralization are used. In conditions of classical and sublevel method excavationsused, the calculated ore losses in ore vein No. 4 are 13.5%, while at the level of all excavations in the Zletovo mines dilution averages at 10%. Ore dilution is also an important technical parameter and several possible variants were calculated. When analyzing the dilution that occurs during the preparation of the sub-level corridor with parameters such: different drop angle (45-60o), constant thickness of 1.47m as the average vein thickness in the calculated ore reserves, width of the sub-level corridor of 1.57m or to the width of the ore veinNo. 4 were added 10cm (left and right to 5cm) as much as is taken in the calculation of the planned dilution and height of 2.5m as suggested for this mining method, it can be noticed that the planned dilution during this method of mining ranges from 26.3% to 42.3%. In conditions of use of this underground method of excavation, parameters are selected that allow for the indicated lowering of the dilution. Namely, the thickness of the ore wire would be 1.47m, the mining width would be 1.57m, only 10cm (left and right up to 5cm) to the thickness of the ore vein will be added, the height difference between the consecutive levels would be 7.5m, dip angle of 45 to 60°, and with the excavation the whole ore vein would be covered in height. On the basis of these parameters, models were prepared in which the ore vein would have a different dip angle, from which the values for the planned ore dilution ranged from 6.7 to 7.8%, which is significantly lower than the average dilution in the Zletovo Mine

Fractional frequency reuse in optical wireless cellular networks

Abstract—Interference coordination in optical wireless cellular networks using different frequency reuse techniques are discussed and compared in this paper. On the one hand, full frequency reuse maximises the system throughput at the cost of poor cell-edge user performance. On the other hand, cluster-based static resource partitioning offers good cell-edge user performance at the cost of low system throughput. Fractional frequency reuse (FFR) is introduced as a compromise between cell-edge user performance and the system throughput with low system complexity. Simulation results show that a guaranteed user throughput of 5.6 Mbps and an average area spectral efficiency (ASE) of 0.3389 bps/Hz/m2 are achieved by the FFR optical wireless system with appropriate power control factors. These results show considerable throughput improvement compared to both benchmark systems. It is also shown that by adjusting the LED transmission optical power of a system using visible light spectrum, the illumination requirement for an office room can be satisfied without extra lighting facilities. Index Terms—optical wireless communications, fractional fre-quency reuse, co-channel interference and orthogonal frequency division multiple access. I