59,799 research outputs found
Pulse Shaping Diversity to Enhance Throughput in Ultra-Dense Small Cell Networks
Spatial multiplexing (SM) gains in multiple input multiple output (MIMO)
cellular networks are limited when used in combination with ultra-dense small
cell networks. This limitation is due to large spatial correlation among
channel pairs. More specifically, it is due to i) line-of-sight (LOS)
communication between user equipment (UE) and base station (BS) and ii)
in-sufficient spacing between antenna elements. We propose to shape transmit
signals at adjacent antennas with distinct interpolating filters which
introduces pulse shaping diversity eventually leading to improved SINR and
throughput at the UEs. In this technique, each antenna transmits its own data
stream with a relative offset with respect to adjacent antenna. The delay which
must be a fraction of symbol period is interpolated with the pulse shaped
signal and generates a virtual MIMO channel that leads to improved diversity
and SINR at the receiver. Note that non-integral sampling periods with
inter-symbol interference (ISI) should be mitigated at the receiver. For this,
we propose to use a fractionally spaced equalizer (FSE) designed based on the
minimum mean squared error (MMSE) criterion. Simulation results show that for a
2x2 MIMO and with inter-site-distance (ISD) of 50 m, the median received SINR
and throughput at the UE improves by a factor of 11 dB and 2x, respectively,
which verifies that pulse shaping can overcome poor SM gains in ultra-dense
small cell networks.Comment: Accepted to 17th IEEE International Workshop on Signal Processing
Advances in Wireless Communication
Noisy Beeping Networks
We introduce noisy beeping networks, where nodes have limited communication
capabilities, namely, they can only emit energy or sense the channel for
energy. Furthermore, imperfections may cause devices to malfunction with some
fixed probability when sensing the channel, which amounts to deducing a noisy
received transmission. Such noisy networks have implications for
ultra-lightweight sensor networks and biological systems.
We show how to compute tasks in a noise-resilient manner over noisy beeping
networks of arbitrary structure. In particular, we transform any algorithm that
assumes a noiseless beeping network (of size ) into a noise-resilient
version while incurring a multiplicative overhead of only in its
round complexity, with high probability. We show that our coding is optimal for
some tasks, such as node-coloring of a clique.
We further show how to simulate a large family of algorithms designed for
distributed networks in the CONGEST() model over a noisy beeping network.
The simulation succeeds with high probability and incurs an asymptotic
multiplicative overhead of in the
round complexity, where is the maximal degree of the network. The
overhead is tight for certain graphs, e.g., a clique. Further, this simulation
implies a constant overhead coding for constant-degree networks
On Fixed Beamforming in Sectored mmWave Ultra Dense Networks at 73GHz
We investigate the use of fixed analogue transmit beamforming for downlink communication in millimetre-wave (mmWave) band ultra-dense networks (UDNs) at 73GHz. Our simulation study is based on 3D radiation patterns using a real design of large planar antenna arrays with different horizontal beamwidths and full characterisation of interference. The effects of network densification are captured through different ratios of the number of access points (APs) to the number of users. We quantify the system\u27s performance by evaluating outage and achievable rate. The results show that users with rates around the mean benefit more from the densification than from narrowing the beamwidth, but for users with low rates, narrow beams also provide a significant increase in throughput
5G Ultra-dense networks with non-uniform Distributed Users
User distribution in ultra-dense networks (UDNs) plays a crucial role in
affecting the performance of UDNs due to the essential coupling between the
traffic and the service provided by the networks. Existing studies are mostly
based on the assumption that users are uniformly distributed in space. The
non-uniform user distribution has not been widely considered despite that it is
much closer to the real scenario. In this paper, Radiation and Absorbing model
(R&A model) is first adopted to analyze the impact of the non-uniformly
distributed users on the performance of 5G UDNs. Based on the R&A model and
queueing network theory, the stationary user density in each hot area is
investigated. Furthermore, the coverage probability, network throughput and
energy efficiency are derived based on the proposed theoretical model. Compared
with the uniformly distributed assumption, it is shown that non-uniform user
distribution has a significant impact on the performance of UDNs.Comment: 14 pages, 10 figure
Medium Access Control for Wireless Sensor Networks based on Impulse Radio Ultra Wideband
This paper describes a detailed performance evaluation of distributed Medium
Access Control (MAC) protocols for Wireless Sensor Networks based on Impulse
Radio Ultra Wideband (IR-UWB) Physical layer (PHY). Two main classes of Medium
Access Control protocol have been considered: Slotted and UnSlotted with
reliability. The reliability is based on Automatic Repeat ReQuest (ARQ). The
performance evaluation is performed using a complete Wireless Sensor Networks
(WSN) simulator built on the Global Mobile Information System Simulator
(GloMoSim). The optimal operating parameters are first discussed for IR-UWB in
terms of slot size, retransmission delay and the number of retransmission, then
a comparison between IR-UWB and other transmission techniques in terms of
reliability latency and power efficiency
Analysis of the IEEE 802.15.4a ultra wideband physical layer through wireless sensor network simulations in OMNET++
Wireless Sensor Networks are the main representative of pervasive computing in large-scale physical environments. These networks consist of a large number of small, wireless devices embedded in the physical world to be used for surveillance, environmental monitoring or other data capture, processing and transfer applications. Ultra wideband has emerged as one of the newest and most promising concepts for wireless technology. Considering all its advantages it seems a likely communication technology candidate for future wireless sensor networks. This paper considers the viability of ultra wideband technology in wireless sensor networks by employing an IEEE 802.15.4a low-rate ultra wideband physical layer model in the OMNET++ simulation environment. An elaborate investigation into the inner workings of the IEEE 802.15.4a UWB physical layer is performed. Simulation experiments are used to provide a detailed analysis of the performance of the IEEE 802.15.4a UWB physical layer over several communication distances. A proposal for a cognitive, adaptive communication approach to optimize for speed and distance is also presented. AFRIKAANS : Draadlose Sensor Netwerke is die hoof verteenwoordiger vir deurdringende rekenarisering in groot skaal fisiese omgewings. Hierdie tipe netwerke bestaan uit ân groot aantal klein, draadlose apparate wat in die fisiese wĂȘreld ingesluit word vir die doel van bewaking, omgewings monitering en vele ander data opvang, verwerk en oordrag applikasies. Ultra wyeband het opgestaan as een van die nuutste en mees belowend konsepte vir draadlose kommunikasie tegnologie. As al die voordele van diĂ© kommunikasie tegnologie in ag geneem word, blyk dit om ân baie goeie kandidaat te wees vir gebruik in toekomstige draadlose sensor netwerke. Hierdie verhandeling oorweeg die vatbaarheid van die gebruik van die ultra wyeband tegnologie in draadlose sensor netwerke deur ân IEEE 802.15.4a lae-tempo ultra wyeband fisiese laag model in die OMNET++ simulasie omgewing toe te pas. ân Breedvoerige ondersoek word geloots om die fyn binneste werking van die IEEE 802.15.4a UWB fisiese laag te verstaan. Simulasie eksperimente word gebruik om ân meer gedetaileerde analiese omtrent die werkverrigting van die IEEE 802.15.4a UWB fisiese laag te verkry oor verskillende kommunikasie afstande. ân Voorstel vir ân omgewings bewuste, aanpasbare kommunikasie tegniek word bespreek met die doel om die spoed en afstand van kommunikasie te optimiseer.Dissertation (MEng)--University of Pretoria, 2011.Electrical, Electronic and Computer Engineeringunrestricte
Mathematical modeling of ultra wideband in vivo radio channel
This paper proposes a novel mathematical model for an in vivo radio channel at ultra-wideband frequencies (3.1â10.6 GHz), which can be used as a reference model for in vivo channel response without performing intensive experiments or simulations. The statistics of error prediction between experimental and proposed model is RMSE = 5.29, which show the high accuracy of the proposed model. Also, the proposed model was applied to the blind data, and the statistics of error prediction is RMSE = 7.76, which also shows a reasonable accuracy of the model. This model will save the time and cost on simulations and experiments, and will help in designing an accurate link budget calculation for a future enhanced system for ultra-wideband body-centric wireless systems
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