Channel Characteristics of MIMO-WLAN Communications at 60GHz for Various Corridors

[[abstract]]A comparison of 4 × 4 multiple-input multiple-output wireless local area network wireless communication characteristics for six different geometrical shapes is investigated. These six shapes include the straight shape corridor with rectangular cross section, the straight shape corridor with arched cross section, the curved shape corridor with rectangular cross section, the curved shape corridor with arched cross section, the L-shape corridor, and the T-shape corridor. The impulse responses of these corridors are computed by applying shooting and bouncing ray/image (SBR/Image) techniques along with inverse Fourier transform. By using the impulse response of these multipath channels, the mean excess delay, root mean square (RMS) delay spread for these six corridors can be obtained. Numerical results show that the capacity for the rectangular cross section corridors is smaller than those for the arched cross section corridors regardless of the shapes. And the RMS delay spreads for the T-and the L-shape corridors are greater than the other corridors.[[notice]]補正完畢[[incitationindex]]SCI[[incitationindex]]EI[[booktype]]紙本[[booktype]]電子

Capacity Analysis of MIMO-WLAN Systems with Single Co-Channel Interference

[[abstract]]In this paper, channel capacity of multiple-input multiple-output wireless local area network (MIMO-WLAN) systems with single co-channel interference (CCI) is calculated. A ray-tracing approach is used to calculate the channel frequency response, which is further used to calculate the corresponding channel capacity. The ability to combat CCI for the MIMO-WLAN simple uniform linear array (ULA) and polarization diversity array (PDA) are investigated. Also the effects caused by two antenna arrays for desired system and CCI are quantified. Numerical results show that MIMO-PDA is better than those of MIMO-ULA when interference is present.[[notice]]補正完畢[[incitationindex]]EI[[booktype]]紙本[[booktype]]電子

Location Optimization for Antennas by Asynchronous Particle Swarm Optimization

[[abstract]]A novel optimisation procedure for the location of the transmitter in 3 × 3 multiple input multiple output wireless local area network wireless communication systems is presented. The optimal antenna location for maximising the channel capacity is searched by particle swarm optimiser (PSO) and asynchronous particle swarm optimisation (APSO). There are two different receiver locations considered in the simulation. These two cases are: (i) the transmitter is mobile in the whole indoor environment and the receivers are located on the tables spaced in intervals uniformly distributed (ii) the transmitter is mobile and the receivers are space in uniformly distributed intervals in the whole indoor environment. Numerical results have shown that the proposed PSO and APSO methods are transmit antenna location is optimised to increase channel capacity. The APSO has better optimisation results compared with the PSO and numerical results also show that the APSO outperforms the PSO in convergence speed.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子

28 GHz and 73 GHz Millimeter-Wave Indoor Propagation Measurements and Path Loss Models

This paper presents 28 GHz and 73 GHz millimeter- wave propagation measurements performed in a typical office environment using a 400 Megachip-per-second broadband sliding correlator channel sounder and highly directional steerable 15 dBi (30 degrees beamwidth) and 20 dBi (15 degrees beamwidth) horn antennas. Power delay profiles were acquired for 48 transmitter-receiver location combinations over distances ranging from 3.9 m to 45.9 m with maximum transmit powers of 24 dBm and 12.3 dBm at 28 GHz and 73 GHz, respectively. Directional and omnidirectional path loss models and RMS delay spread statistics are presented for line-of-sight and non-line-of-sight environments for both co- and cross-polarized antenna configurations. The LOS omnidirectional path loss exponents were 1.1 and 1.3 at 28 GHz and 73 GHz, and 2.7 and 3.2 in NLOS at 28 GHz and 73 GHz, respectively, for vertically-polarized antennas. The mean directional RMS delay spreads were 18.4 ns and 13.3 ns, with maximum values of 193 ns and 288 ns at 28 GHz and 73 GHz, respectively.Comment: 7 pages, 9 figures, 2015 IEEE International Conference on Communications (ICC), ICC Workshop

Coverage prediction and optimization algorithms for indoor environments

A heuristic algorithm is developed for the prediction of indoor coverage. Measurements on one floor of an office building are performed to investigate propagation characteristics and validations with very limited additional tuning are performed on another floor of the same building and in three other buildings. The prediction method relies on the free-space loss model for every environment, this way intending to reduce the dependency of the model on the environment upon which the model is based, as is the case with many other models. The applicability of the algorithm to a wireless testbed network with fixed WiFi 802.11b/g nodes is discussed based on a site survey. The prediction algorithm can easily be implemented in network planning algorithms, as will be illustrated with a network reduction and a network optimization algorithm. We aim to provide an physically intuitive, yet accurate prediction of the path loss for different building types

Antennas and Propagation Aspects for Emerging Wireless Communication Technologies

The increasing demand for high data rate applications and the delivery of zero-latency multimedia content drives technological evolutions towards the design and implementation of next-generation broadband wireless networks. In this context, various novel technologies have been introduced, such as millimeter wave (mmWave) transmission, massive multiple input multiple output (MIMO) systems, and non-orthogonal multiple access (NOMA) schemes in order to support the vision of fifth generation (5G) wireless cellular networks. The introduction of these technologies, however, is inextricably connected with a holistic redesign of the current transceiver structures, as well as the network architecture reconfiguration. To this end, ultra-dense network deployment along with distributed massive MIMO technologies and intermediate relay nodes have been proposed, among others, in order to ensure an improved quality of services to all mobile users. In the same framework, the design and evaluation of novel antenna configurations able to support wideband applications is of utmost importance for 5G context support. Furthermore, in order to design reliable 5G systems, the channel characterization in these frequencies and in the complex propagation environments cannot be ignored because it plays a significant role. In this Special Issue, fourteen papers are published, covering various aspects of novel antenna designs for broadband applications, propagation models at mmWave bands, the deployment of NOMA techniques, radio network planning for 5G networks, and multi-beam antenna technologies for 5G wireless communications

Enhancing wireless communication system performance through modified indoor environments

This thesis reports the methods, the deployment strategies and the resulting system performance improvement of in-building environmental modification. With the increasing use of mobile computing devices such as PDAs, laptops, and the expansion of wireless local area networks (WLANs), there is growing interest in increasing productivity and efficiency through enhancing received signal power. This thesis proposes the deployment of waveguides consisting of frequency selective surfaces (FSSs) in indoor wireless environments and investigates their effect on radio wave propagation. The received power of the obstructed (OBS) path is attenuated significantly as compared with that of the line of sight (LOS) path, thereby requiring an additional link budget margin as well as increased battery power drain. In this thesis, the use of an innovative model is also presented to selectively enhance radio propagation in indoor areas under OBS conditions by reflecting the channel radio signals into areas of interest in order to avoid significant propagation loss. An FSS is a surface which exhibits reflection and/or transmission properties as a function of frequency. An FSS with a pass band frequency response was applied to an ordinary or modified wall as a wallpaper to transform the wall into a frequency selective (FS) wall (FS-WALL) or frequency selective modified wall (FS-MWALL). Measurements have shown that the innovative model prototype can enhance 2.4GHz (IEEE 802.11b/g/n) transmissions in addition to the unmodified wall, whereas other radio services, such as cellular telephony at 1.8GHz, have other routes to penetrate or escape. The FSS performance has been examined intensely by both equivalent circuit modelling, simulation, and practical measurements. Factors that influence FSS performance such as the FSS element dimensions, element conductivities, dielectric substrates adjacent to the FSS, and signal incident angles, were investigated. By keeping the elements small and densely packed, a largely angle-insensitive FSS was developed as a promising prototype for FSS wallpaper. Accordingly, the resultant can be modelled by cascading the effects of the FSS wallpaper and the ordinary wall (FSWALL) or modified wall (FS-MWALL). Good agreement between the modelled, simulated, and the measured results was observed. Finally, a small-scale indoor environment has been constructed and measured in a half-wave chamber and free space measurements in order to practically verify this approach and through the usage of the deterministic ray tracing technique. An initial investigation showing that the use of an innovative model can increase capacity in MIMO systems. This can be explained by the presence of strong multipath components which give rise to a low correlated Rayleigh Channel. This research work has linked the fields of antenna design, communication systems, and building architecture

SNR-based evaluation of coexistence in wireless system of hospital

Abstract. The wireless system (IEEE Std. 802.11) of North Karelian Central Hospital (NKCH) has been studied in the newly opened J2 building of the hospital. The measurements have been carried out using Ekahau Sidekick spectrum analyser and Ekahau Pro software. Signal propagation has been modelled in the control ward of the Emergency department because many coexisting systems are used with critical requirements of data communication over there. The analytical models have been developed to understand the radio-frequency (RF) signal propagation in the entire building. Measurements have also been carried out on the entire first floor, in the Department of the Abdominal Diseases on the ground floor and in the Children’s wards on the third floor. The multi-slope path-loss propagation models with shadowing have been generated based on the Received Signal Strength Indicator (RSSI) measurements for typical hospital environment at the 2.4 GHz and 5 GHz Industrial, Scientific, and Medical (ISM) band. The measurements have been carried out within the two predefined routes. The models have also been compared to the empirically derived path-loss models. The probability of signal outage has been calculated for both measured routes. The aggregate interference has been measured within the routes that cover the area where remarkable signal variations and the high level of interference has been indicated based on the heatmaps of Ekahau. The use of Ekahau Sidekick and Ekahau Pro software in the coexistence study has been described. The noise floor has been determined based on the averaged values of the six measurement campaigns. The local changes in signal strength of the desired signal and aggregated power of interference have been studied. The Signal-to-Interference Ratio (SIR) models have been generated within the measured routes. The rapid decreases of Signal-to-Noise Ratio (SNR) have been indicated on all measured floors of building J2. They have been studied and their effect on the network performance has been evaluated. The evaluation has been done by comparing the measured values of RSSI, SNR and SIR to the requirements of the respective Modulation and Coding Scheme (MCS). The link margins have been calculated based on the chosen bit error probability and the given SNR requirement of the respective MCS. The comparison between the measured RSSI readings and the required threshold of the respective MCS has been done using the defined shadowing as a link margin. It has been shown that the measured difference between the signal strength of the 2.4 GHz and 5 GHz bands has been caused by the reduced transmit power at the 2.4 GHz band. Based on the SIR measurements, it has been shown that the access points of the neighbouring building have contributed locally to the measured aggregate interference in the Control ward. However, the primary reason for the decrease of SIR at the 2.4 GHz band has been the decrease of desired signal power that has been contributed by the above mentioned reduced transmit power. The strong SNR drops have been indicated on every measured floor before the roaming has occurred.Sairaalan langattoman järjestelmän arviointi signaali-kohina-suhteen avulla. Tiivistelmä. Tässä diplomityössä on tutkittu Pohjois-Karjalan keskussairaalan (PKKS) langatonta verkkoa (IEEE Std. 802.11) äskettäin avatussa sairaalan laajennusosassa (J2-rakennus). Mittaukset on toteutettu käyttäen Ekahau Sidekick spektrianalysaattoria ja Ekahau Pro -ohjelmaa. Päivystyksen valvontaosasto on valittu tutkimuskohteeksi, koska siellä käytetään paljon eri teknologioihin perustuvia järjestelmiä, joiden välinen tiedonsiirto on luonteeltaan kriittistä. Luotujen mallien avulla rakennuksen langatonta toimintaympäristöä tutkitaan RF-järjestelmän (Radio-Frequency) näkökulmasta myös muissa mittausten kohteina olleissa tiloissa. Mittauksia on tehty myös valvontaosaston ulkopuolella 1. kerroksessa sekä 3. kerroksen lastenosastoilla ja Vatsakeskuksen tiloissa pohjakerroksessa. RSSI-mittausten perusteella on luotu radiotiehäviöihin perustuvat etenemismallit molemmilla käytössä olevilla ISM-taajuuskaistoilla (Industrial, Scientific and Medical bands). Varjostuminen ja etenemishäviökertoimen muutokset on otettu huomioon etenemismalleissa. Mittaukset on suoritettu ennalta määritellyillä reiteillä. Luotuja malleja on verrattu myös tutkimuskirjallisuudessa esitettyihin, empiirisesti johdettuihin etenemishäviömalleihin. Signaalikatkoksen todennäköisyys on laskettu molemmille reiteille 2.4 GHz:n taajuuskaistalla. Vastaanotetun häiriötehon summa on mitattu koko mallinnettavan tilan alueelle ulottuvien mittausreittien pohjalta. Mittausreitit on määritelty Ekahau Pron tuottamien kuuluvuus- ja häiriökarttojen avulla ottaen huomioon havaitut signaalitason vaihtelut. Ekahau Sidekick -spektrianalysaattorin ja Ekahau Pro -ohjelman käyttöä on kuvattu tämän tutkimuksen kontekstissa. Kohinataso on määritelty kaikissa kuudessa mittauskampanjassa mitattujen kohina-tehoarvojen keskiarvona. Paikallisten hyötysignaalinvoimakkuus- ja häiriötehovaihteluiden vaikutusta verkon suorituskykyyn on tutkittu ja molemmat mittausreitit kattavat SIR-mallit (Signal-to-Interference Ratio) on luotu. Kaikissa tutkituissa kerroksissa havaittuja äkillisiä signaali-kohinasuhteen vaihteluita on tutkittu ja niiden vaikutusta järjestelmän suorituskykyyn on arvioitu. Mitattujen hyöty- ja häiriösignaalivaihteluiden arviointi on toteutettu vertaamalla mittaamalla saatuja SNR- (Signal-to-Noise ratio), SIR- ja RSSI-arvoja (Received Signal Strength Indicator) eri tiedonsiirtonopeuksia käyttävien MCS-indeksien vaatimiin signaalinvoimakkuus- ja signaali-kohina-suhteen arvoihin. Kynnysarvoille on laskettu linkkimarginaalit käyttäen mitoitusvaatimuksena valittua bittivirhetodennäköisyyden arvoa. Mitattuja RSSI-arvoja on verrattu käyttäen linkkimarginaalina etenemismallinnuksessa määritettyjä varjostumisvaikutuksen arvoja. 2.4 ja 5 GHz:n taajuusalueiden välillä mitatun signaalinvoimakkuuseron on tutkimuksessa saatujen tulosten perusteella osoitettu olevan seurausta alennetusta lähetystehosta 2.4 GHz:n kaistalla. SIR-mittausten perusteella on todettu viereisen rakennuksen tukiasemien kasvattaneen vastaanotettua häiriötehosummaa valvontaosastolla paikallisesti. Ensisijainen syy mitattuihin SIR-arvojen vaihteluihin ovat kuitenkin alhainen signaalinvoimakkuus 2.4 GHz:n kaistalla, mikä osittain johtuu edellä kuvatusta alennetusta lähetystehosta. Voimakkaita SNR-vaihteluita on mitattu kaikissa kerroksissa ennen kuin päätelaite kytkeytyy uuteen tukiasemaan

Optimal receiver antenna location in indoor environment using dynamic differential evolution and genetic algorithm

Using the impulse responses of these multipath channels, the bit error rate (BER) performance for binary pulse amplitude modulation impulse radio ultra-wideband communication system is calculated. The optimization location of receiving antenna is investigated by dynamic differential evolution (DDE) and genetic algorithm (GA) to minimize the outage probability. Numerical results show that the performance for reducing BER and outage probability by DDE algorithm is better than that by GA